[Federal Register Volume 68, Number 154 (Monday, August 11, 2003)]
[Proposed Rules]
[Pages 47640-47795]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-18295]



[[Page 47639]]

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Part II





Environmental Protection Agency





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40 CFR Parts 141 and 142



National Primary Drinking Water Regulations: Long Term 2 Enhanced 
Surface Water Treatment Rule; Proposed Rule

  Federal Register / Vol. 68, No. 154 / Monday, August 11, 2003 / 
Proposed Rules  

[[Page 47640]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 141 and 142

[FRL-7530-5]
RIN 2040--AD37


National Primary Drinking Water Regulations: Long Term 2 Enhanced 
Surface Water Treatment Rule

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: In this document, the Environmental Protection Agency (EPA) is 
proposing National Primary Drinking Water Regulations that require the 
use of treatment techniques, along with monitoring, reporting, and 
public notification requirements, for all public water systems (PWSs) 
that use surface water sources. The purposes of the Long Term 2 
Enhanced Surface Water Treatment Rule (LT2ESWTR) are to improve control 
of microbial pathogens, including specifically the protozoan 
Cryptosporidium, in drinking water and to address risk-risk trade-offs 
with the control of disinfection byproducts. Key provisions in today's 
proposed LT2ESWTR include the following: source water monitoring for 
Cryptosporidium, with reduced monitoring requirements for small 
systems; additional Cryptosporidium treatment for filtered systems 
based on source water Cryptosporidium concentrations; inactivation of 
Cryptosporidium by all unfiltered systems; disinfection profiling and 
benchmarking to ensure continued levels of microbial protection while 
PWSs take the necessary steps to comply with new disinfection byproduct 
standards; covering, treating, or implementing a risk management plan 
for uncovered finished water storage facilities; and criteria for a 
number of treatment and management options (i.e., the microbial 
toolbox) that PWSs may implement to meet additional Cryptosporidium 
treatment requirements. The LT2ESWTR will build upon the treatment 
technique requirements of the Interim Enhanced Surface Water Treatment 
Rule and the Long Term 1 Enhanced Surface Water Treatment Rule.
    EPA believes that implementation of the LT2ESWTR will significantly 
reduce levels of Cryptosporidium in finished drinking water. This will 
substantially lower rates of endemic cryptosporidiosis, the illness 
caused by Cryptosporidium, which can be severe and sometimes fatal in 
sensitive subpopulations (e.g., AIDS patients, the elderly). In 
addition, the treatment technique requirements of this proposal are 
expected to increase the level of protection from exposure to other 
microbial pathogens (e.g., Giardia lamblia).

DATES: EPA must receive public comment on the proposal by November 10, 
2003.

ADDRESSES: Comments may be submitted by mail to: Water Docket, 
Environmental Protection Agency, Mail Code 4101T, 1200 Pennsylvania 
Ave., NW., Washington, DC 20460, Attention Docket ID No. OW-2002-0039. 
Comments may also be submitted electronically or through hand delivery/
courier by following the detailed instructions as provided in section 
I.C. of the SUPPLEMENTARY INFORMATION section.

FOR FURTHER INFORMATION CONTACT: For technical inquiries, contact 
Daniel Schmelling, Office of Ground Water and Drinking Water (MC 
4607M), U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., 
NW., Washington, DC 20460; telephone (202) 564-5281. For regulatory 
inquiries, contact Jennifer McLain at the same address; telephone (202) 
564-5248. For general information contact the Safe Drinking Water 
Hotline, Telephone (800) 426-4791. The Safe Drinking Water Hotline is 
open Monday through Friday, excluding legal holidays, from 9 a.m. to 
5:30 p.m. Eastern Time.

SUPPLEMENTARY INFORMATION:

I. General Information

A. Who Is Regulated by This Action?

    Entities potentially regulated by the LT2ESWTR are public water 
systems (PWSs) that use surface water or ground water under the direct 
influence of surface water (GWUDI). Regulated categories and entities 
are identified in the following chart.

------------------------------------------------------------------------
                Category                  Examples of regulated entities
------------------------------------------------------------------------
Industry...............................  Public Water Systems that use
                                          surface water or ground water
                                          under the direct influence of
                                          surface water.
State, Local, Tribal or Federal          Public Water Systems that use
 Governments.                             surface water or ground water
                                          under the direct influence of
                                          surface water.
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in this table could also be regulated. To determine whether 
your facility is regulated by this action, you should carefully examine 
the definition of public water system in Sec.  141.3 of Title 40 of the 
Code of Federal Regulations and applicability criteria in Sec. Sec.  
141.76 and 141.501 of today's proposal. If you have questions regarding 
the applicability of the LT2ESWTR to a particular entity, consult one 
of the persons listed in the preceding section entitled FOR FURTHER 
INFORMATION CONTACT

B. How Can I Get Copies of This Document and Other Related Information?

    1. Docket. EPA has established an official public docket for this 
action under Docket ID No. OW-2002-0039. The official public docket 
consists of the documents specifically referenced in this action, any 
public comments received, and other information related to this action. 
Although a part of the official docket, the public docket does not 
include Confidential Business Information (CBI) or other information 
whose disclosure is restricted by statute. The official public docket 
is the collection of materials that is available for public viewing at 
the Water Docket in the EPA Docket Center, (EPA/DC) EPA West, Room 
B102, 1301 Constitution Ave., NW., Washington, DC. The EPA Docket 
Center Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday 
through Friday, excluding legal holidays. The telephone number for the 
Public Reading Room is (202) 566-1744, and the telephone number for the 
Water Docket is (202) 566-2426. For access to docket material, please 
call (202) 566-2426 to schedule an appointment.
    2. Electronic Access. You may access this Federal Register document 
electronically through the EPA Internet under the ``Federal Register'' 
listings at http://www.epa.gov/fedrgstr/.
    An electronic version of the public docket is available through 
EPA's electronic public docket and comment system, EPA Dockets. You may 
use EPA Dockets at http://www.epa.gov/edocket/ to submit or view public 
comments, access the index listing of the contents of the official 
public docket, and to access those documents in the public docket that 
are available electronically. Once in the system, select ``search,'' 
then key in the appropriate docket identification number.
    Certain types of information will not be placed in the EPA Dockets. 
Information claimed as CBI and other

[[Page 47641]]

information whose disclosure is restricted by statute, which is not 
included in the official public docket, will not be available for 
public viewing in EPA's electronic public docket. EPA's policy is that 
copyrighted material will not be placed in EPA's electronic public 
docket but will be available only in printed, paper form in the 
official public docket. Although not all docket materials may be 
available electronically, you may still access any of the publicly 
available docket materials through the docket facility identified in 
section I.B.1.
    For public commenters, it is important to note that EPA's policy is 
that public comments, whether submitted electronically or in paper, 
will be made available for public viewing in EPA's electronic public 
docket as EPA receives them and without change, unless the comment 
contains copyrighted material, CBI, or other information whose 
disclosure is restricted by statute. When EPA identifies a comment 
containing copyrighted material, EPA will provide a reference to that 
material in the version of the comment that is placed in EPA's 
electronic public docket. The entire printed comment, including the 
copyrighted material, will be available in the public docket.
    Public comments submitted on computer disks that are mailed or 
delivered to the docket will be transferred to EPA's electronic public 
docket. Public comments that are mailed or delivered to the Docket will 
be scanned and placed in EPA's electronic public docket. Where 
practical, physical objects will be photographed, and the photograph 
will be placed in EPA's electronic public docket along with a brief 
description written by the docket staff.

C. How and to Whom Do I Submit Comments?

    You may submit comments electronically, by mail, or through hand 
delivery/courier. To ensure proper receipt by EPA, identify the 
appropriate docket identification number in the subject line on the 
first page of your comment. Please ensure that your comments are 
submitted within the specified comment period. Comments received after 
the close of the comment period will be marked ``late.'' EPA is not 
required to consider these late comments.
    1. Electronically. If you submit an electronic comment as 
prescribed below, EPA recommends that you include your name, mailing 
address, and an e-mail address or other contact information in the body 
of your comment. Also include this contact information on the outside 
of any disk or CD ROM you submit, and in any cover letter accompanying 
the disk or CD ROM. This ensures that you can be identified as the 
submitter of the comment and allows EPA to contact you in case EPA 
cannot read your comment due to technical difficulties or needs further 
information on the substance of your comment. EPA's policy is that EPA 
will not edit your comment, and any identifying or contact information 
provided in the body of a comment will be included as part of the 
comment that is placed in the official public docket, and made 
available in EPA's electronic public docket. If EPA cannot read your 
comment due to technical difficulties and cannot contact you for 
clarification, EPA may not be able to consider your comment.
    a. EPA Dockets. Your use of EPA's electronic public docket to 
submit comments to EPA electronically is EPA's preferred method for 
receiving comments. Go directly to EPA Dockets at http://www.epa.gov/edocket, and follow the online instructions for submitting comments. 
Once in the system, select ``search,'' and then key in Docket ID No. 
OW-2002-0039. The system is an ``anonymous access'' system, which means 
EPA will not know your identity, e-mail address, or other contact 
information unless you provide it in the body of your comment.
    b. E-mail. Comments may be sent by electronic mail (e-mail) to [email protected], Attention Docket ID No. OW-2002-0039. In contrast to 
EPA's electronic public docket, EPA's e-mail system is not an 
``anonymous access'' system. If you send an e-mail comment directly to 
the Docket without going through EPA's electronic public docket, EPA's 
e-mail system automatically captures your e-mail address. E-mail 
addresses that are automatically captured by EPA's e-mail system are 
included as part of the comment that is placed in the official public 
docket, and made available in EPA's electronic public docket.
    c. Disk or CD ROM. You may submit comments on a disk or CD ROM that 
you mail to the mailing address identified in section I.C.2. These 
electronic submissions will be accepted in WordPerfect or ASCII file 
format. Avoid the use of special characters and any form of encryption.
    2. By Mail. Send three copies of your comments and any enclosures 
to: Water Docket, Environmental Protection Agency, Mail Code 4101T, 
1200 Pennsylvania Ave., NW., Washington, DC, 20460, Attention Docket ID 
No. OW-2002-0039.
    3. By Hand Delivery or Courier. Deliver your comments to: Water 
Docket, EPA Docket Center, Environmental Protection Agency, Room B102, 
1301 Constitution Ave., NW, Washington, DC, Attention Docket ID No. OW-
2002-0039. Such deliveries are only accepted during the Docket's normal 
hours of operation as identified in section I.B.1.

D. What Should I Consider as I Prepare My Comments for EPA?

    You may find the following suggestions helpful for preparing your 
comments:
    1. Explain your views as clearly as possible.
    2. Describe any assumptions that you used.
    3. Provide any technical information and/or data you used that 
support your views.
    4. If you estimate potential burden or costs, explain how you 
arrived at your estimate.
    5. Provide specific examples to illustrate your concerns.
    6. Offer alternatives.
    7. Make sure to submit your comments by the comment period deadline 
identified.
    8. To ensure proper receipt by EPA, identify the appropriate docket 
identification number in the subject line on the first page of your 
response. It would also be helpful if you provided the name, date, and 
Federal Register citation related to your comments.

Abbreviations Used in This Document

AIPC All Indian Pueblo Council
ASDWA Association of State Drinking Water Administrators
ASTM American Society for Testing and Materials
AWWA American Water Works Association
AWWARF American Water Works Association Research Foundation
[deg]C Degrees Centigrade
CCP Composite Correction Program
CDC Centers for Disease Control and Prevention
CFE Combined Filter Effluent
CFR Code of Federal Regulations
COI Cost-of-Illness
CT The Residual Concentration of Disinfectant (mg/L) Multiplied by the 
Contact Time (in minutes)
CWS Community Water Systems
DAPI 4',6-Diamindino-2-phenylindole
DBPs Disinfection Byproducts
DBPR Disinfectants/Disinfection Byproducts Rule
DE Diatomaceous Earth
DIC Differential Interference Contrast (microscopy)
EA Economic Analysis

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EPA United States Environmental Protection Agency
GAC Granular Activated Carbon
GWUDI Ground Water Under the Direct Influence of Surface Water
HAA5 Haloacetic acids (Monochloroacetic, Dichloroacetic, 
Trichloroacetic, Monobromoacetic and Dibromoacetic Acids)
HPC Heterotrophic Plate Count
ICR Information Collection Request
ICRSS Information Collection Rule Supplemental Surveys
ICRSSM Information Collection Rule Supplemental Survey of Medium 
Systems
ICRSSL Information Collection Rule Supplemental Survey of Large Systems
IESWTR Interim Enhanced Surface Water Treatment Rule
IFA Immunofluorescence Assay
Log Logarithm (common, base 10)
LRAA Locational Running Annual Average
LRV Log Removal Value
LT1ESWTR Long Term 1 Enhanced Surface Water Treatment Rule
LT2ESWTR Long Term 2 Enhanced Surface Water Treatment Rule
MCL Maximum Contaminant Level
MCLG Maximum Contaminant Level Goal
MGD Million Gallons per Day
M-DBP Microbial and Disinfectants/Disinfection Byproducts
MF Microfiltration
NCWS Non-community water systems
NF Nanofiltration
NODA Notice of Data Availability
NPDWR National Primary Drinking Water Regulation
NTNCWS Non-transient Non-community Water System
NTTAA National Technology Transfer and Advancement Act
NTU Nephelometric Turbidity Unit
OMB Office of Management and Budget
PE Performance Evaluation
PWS Public Water System
QC Quality Control
QCRV Quality Control Release Value
RAA Running Annual Average
RFA Regulatory Flexibility Act
RO Reverse Osmosis
RSD Relative Standard Deviation
SAB Science Advisory Board
SBAR Small Business Advocacy Review
SERs Small Entity Representatives
SDWA Safe Drinking Water Act
SWTR Surface Water Treatment Rule
TCR Total Coliform Rule
TTHM Total Trihalomethanes
TNCWS Transient Non-community Water Systems
UF Ultrafiltration
UMRA Unfunded Mandates Reform Act

Table of Contents

    I. Summary
    A. Why Is EPA Proposing the LT2ESWTR?
    B. What Does the LT2ESWTR Proposal Require?
    1. Treatment Requirements for Cryptosporidium
    2. Disinfection Profiling and Benchmarking
    3. Uncovered Finished Water Storage Facilities
    C. Will This Proposed Regulation Apply to My Water System?
II. Background
    A. What Is the Statutory Authority for the LT2ESWTR?
    B. What Current Regulations Address Microbial Pathogens in 
Drinking Water?
    1. Surface Water Treatment Rule
    2. Total Coliform Rule
    3. Interim Enhanced Surface Water Treatment Rule
    4. Long Term 1 Enhanced Surface Water Treatment Rule
    5. Filter Backwash Recycle Rule
    C. What Public Health Concerns Does This Proposal Address?
    1. Introduction
    2. Cryptosporidium Health Effects and Outbreaks
    a. Health Effects
    b. Waterborne Cryptosporidiosis Outbreaks.
    3. Remaining Public Health Concerns Following the IESWTR and 
LT1ESWTR
    a. Adequacy of Physical Removal To Control Cryptosporidium and 
the Need for Risk Based Treatment Requirements.
    b. Control of Cryptosporidium in Unfiltered Systems
    c. Uncovered Finished Water Storage Facilities
    D. Federal Advisory Committee Process
III. New Information on Cryptosporidium Health Risks and Treatment
    A. Overview of Critical Factors for Evaluating Regulation of 
Microbial Pathogens
    B. Cryptosporidium Infectivity
    1. Cryptosporidium Infectivity Data Evaluated for IESWTR
    2. New Data on Cryptosporidium Infectivity
    3. Significance of New Infectivity Data
    C. Cryptosporidium Occurrence
    1. Occurrence Data Evaluated for IESWTR
    a. Filtered Systems.
    b. Unfiltered Systems
    2. Overview of the Information Collection Rule and Information 
Collection Rule Supplemental Surveys (ICRSS)
    a. Scope of the Information Collection Rule
    b. Scope of the ICRSS
    3. Analytical Methods for Protozoa in the Information Collection 
Rule and ICRSS
    a. Information Collection Rule Protozoan Method
    b. Method 1622 and Method 1623
    4. Cryptosporidium Occurrence Results from the Information 
Collection Rule and ICRSS
    a. Information Collection Rule Results
    b. ICRSS Results
    5. Significance of New Cryptosporidium Occurrence Data
    6. Request for Comment on Information Collection Rule and ICRSS 
Data Sets
    D. Treatment
    1. Overview
    2. Treatment Information Considered for the IESWTR and LT1ESWTR
    a. Physical Removal
    b. Inactivation
    3. New Information on Treatment for Control of Cryptosporidium
    a. Conventional Filtration Treatment and Direct Filtration
    i. Dissolved Air Flotation.
    b. Slow Sand Filtration
    c. Diatomaceous Earth Filtration
    d. Other Filtration Technologies
    e. Inactivation
    i. Ozone and Chlorine Dioxide
    ii. Ultraviolet Light
    iii. Significance of New Information on Inactivation
IV. Discussion of Proposed LT2ESWTR Requirements
    A. Additional Cryptosporidium Treatment Technique Requirements 
for Filtered Systems
    1. What Is EPA Proposing Today?
    a. Overview of Framework Approach
    b. Monitoring Requirements
    c. Treatment Requirements
    i. Bin Classification
    ii. Credit for Treatment in Place
    iii. Treatment Requirements Associated With LT2ESWTR Bins
    d. Use of Previously Collected Data
    2. How Was This Proposal Developed?
    a. Basis for Targeted Treatment Requirements
    b. Basis for Bin Concentration Ranges and Treatment Requirements
    i. What Is the Risk Associated With a Given Level of 
Cryptosporidium in a Drinking Water Source?
    ii. What Degree of Additional Treatment Should Be Required for a 
Given Source Water Cryptosporidium Level?
    c. Basis for Source Water Monitoring Requirements
    i. Systems Serving at Least 10,000 People
    ii. Systems Serving Fewer Than 10,000 People
    iii. Future Monitoring and Reassessment
    d. Basis for Accepting Previously Collected Data
    3. Request for Comment
    B. Unfiltered System Treatment Technique Requirements for 
Cryptosporidium
    1. What Is EPA Proposing Today?
    a. Overview
    b. Monitoring Requirements
    c. Treatment Requirements
    2. How Was This Proposal Developed?
    a. Basis for Cryptosporidium Treatment Requirements
    b. Basis for Requiring the Use of Two Disinfectants
    c. Basis for Source Water Monitoring Requirements
    3. Request for Comment
    C. Options for Systems to Meet Cryptosporidium Treatment 
Requirements
    1. Microbial Toolbox Overview
    2. Watershed Control Program
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    3. Alternative Source

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    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    4. Off-stream Raw Water Storage
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    5. Pre-sedimentation With Coagulant
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    i. Published Studies of Cryptosporidium Removal by Conventional 
Sedimentation Basins
    ii. Data Supplied by Utilities on the Removal of Spores by 
Presedimentation
    c. Request for Comment
    6. Bank Filtration
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    7. Lime Softening
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    8. Combined Filter Performance
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    9. Roughing Filter
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    10. Slow Sand Filtration
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    11. Membrane Filtration
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    12. Bag and Cartridge Filtration
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    13. Secondary Filtration
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    14. Ozone and Chlorine Dioxide
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comments
    15. Ultraviolet Light
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    16. Individual Filter Performance
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    17. Other Demonstration of Performance
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    D. Disinfection Benchmarks for Giardia lamblia and Viruses
    1. What Is EPA Proposing Today?
    a. Applicability and Schedule
    b. Developing the Disinfection Profile and Benchmark
    c. State Review
    2. How Was This Proposal Developed?
    3. Request for Comments
    E. Additional Treatment Technique Requirements for Systems with 
Uncovered Finished Water Storage Facilities
    1. What Is EPA Proposing Today?
    2. How Was This Proposal Developed?
    3. Request for Comments
    F. Compliance Schedules
    1. What Is EPA Proposing Today?
    a. Source Water Monitoring
    i. Filtered Systems
    ii. Unfiltered Systems
    b. Treatment Requirements
    c. Disinfection Benchmarks for Giardia lamblia and Viruses
    2. How Was This Proposal Developed?
    3. Request for Comments
    G. Public Notice Requirements
    1. What Is EPA Proposing Today?
    2. How Was This Proposal Developed?
    3. Request for Comment
    H. Variances and Exemptions
    1. Variances
    2. Exemptions
    3. Request for Comment
    a. Variances
    b. Exemptions
    I. Requirements for Systems To Use Qualified Operators
    J. System Reporting and Recordkeeping Requirements
    1. Overview
    2. Reporting Requirements for Source Water Monitoring
    a. Data Elements To Be Reported
    b. Data System
    c. Previously Collected Monitoring Data
    3. Compliance With Additional Treatment Requirements
    4. Request for Comment
    K. Analytical Methods
    1. Cryptosporidium
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    2. E. coli
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    3. Turbidity
    a. What Is EPA Proposing Today?
    b. How Was This Proposal Developed?
    c. Request for Comment
    L. Laboratory Approval
    1. Cryptosporidium Laboratory Approval
    2. E. coli Laboratory Approval
    3. Turbidity Analyst Approval
    4. Request for Comment
    M. Requirements for Sanitary Surveys Conducted by EPA
    1. Overview
    2. Background
    3. Request for Comment
V. State Implementation
    A. Special State Primacy Requirements
    B. State Recordkeeping Requirements
    C. State Reporting Requirements
    D. Interim Primacy
VI. Economic Analysis
    A. What Regulatory Alternatives Did the Agency Consider?
    B. What Analyses Support Selecting the Proposed Rule Option?
    C. What Are the Benefits of the Proposed LT2ESWTR?
    1. Non-quantifiable Health and Non-health Related Benefits
    2. Quantifiable Health Benefits
    a. Filtered Systems
    b. Unfiltered Systems
    3. Timing of Benefits Accrual (latency)
    D. What Are the Costs of the Proposed LT2ESWTR?
    1. Total Annualized Present Value Costs
    2. Water System Costs
    a. Source Water Monitoring Costs
    b. Filtered Systems Treatment Costs
    c. Unfiltered Systems Treatment Costs
    d. Uncovered Finished Water Storage Facilities
    e. Future Monitoring Costs
    f. Sensitivity Analysis-influent Bromide Levels on Technology 
Selection for Filtered Plants
    3. State/Primacy Agency Costs
    4. Non-quantified Costs
    E. What Are the Household Costs of the Proposed Rule?
    F. What Are the Incremental Costs and Benefits of the Proposed 
LT2ESWTR?
    G. Are There Benefits From the Reduction of Co-occurring 
Contaminants?
    H. Are There Increased Risks From Other Contaminants?
    I. What Are the Effects of the Contaminant on the General 
Population and Groups Within the General Populations That Are 
Identified as Likely to be at Greater Risk of Adverse Health 
Effects?
    J. What Are the Uncertainties in the Baseline, Risk, Benefit, 
and Cost Estimates for the Proposed LT2ESWTR as well as the Quality 
and Extent of the Information?
    K. What Is the Benefit/Cost Determination for the Proposed 
LT2ESWTR?
    L. Request for Comment
VII. Statutory and Executive Order Reviews
    A. Executive Order 12866: Regulatory Planning and Review
    B. Paperwork Reduction Act
    C. Regulatory Flexibility Act
    D. Unfunded Mandates Reform Act
    1. Summary of UMRA Requirements
    2. Written Statement for Rules With Federal mandates of $100 
million or more
    a. Authorizing Legislation
    b. Cost-benefit Analysis
    c. Estimates of Future Compliance Costs and Disproportionate 
Budgetary Effects
    d. Macro-economic Effects
    e. Summary of EPA Consultation With State, local, and Tribal 
Governments and Their Concerns
    f. Regulatory Alternatives Considered
    g. Selection of the Least Costly, Most Cost-effective, or Least 
Burdensome Alternative That Achieves the Objectives of the Rule
    3. Impacts on Small Governments
    E. Executive Order 13132: Federalism
    F. Executive Order 13175: Consultation and Coordination With 
Indian Tribal Governments
    G. Executive Order 13045: Protection of Children from 
Environmental Health and Safety Risks
    H. Executive Order 13211: Actions that Significantly Affect 
Energy Supply, Distribution, or Use
    I. National Technology Transfer and Advancement Act
    J. Executive Order 12898: Federal Actions to Address 
Environmental Justice in Minority Populations or Low-Income 
Populations

[[Page 47644]]

    K. Consultations With the Science Advisory Board, National 
Drinking Water Advisory Council, and the Secretary of Health and 
Human Services
    L. Plain Language
VIII. References

I. Summary

A. Why Is EPA Proposing the LT2ESWTR?

    EPA is proposing the Long Term 2 Enhanced Surface Water Treatment 
Rule (LT2ESWTR) to provide for increased protection against microbial 
pathogens in public water systems that use surface water sources. The 
proposed LT2ESWTR focuses on Cryptosporidium, which is a protozoan 
pathogen that is widespread in surface water. EPA is particularly 
concerned about Cryptosporidium because it is highly resistant to 
inactivation by standard disinfection practices like chlorination. 
Ingestion of Cryptosporidium oocysts can cause acute gastrointestinal 
illness, and health effects in sensitive subpopulations may be severe, 
including risk of mortality. Cryptosporidium has been identified as the 
pathogenic agent in a number of waterborne disease outbreaks across the 
U.S. and in Canada (details in section II).
    The intent of the LT2ESWTR is to supplement existing microbial 
treatment requirements for systems where additional public health 
protection is needed. Currently, the Interim Enhanced Surface Water 
Treatment Rule (IESWTR) requires large systems that filter to remove at 
least 99% (2 log) of Cryptosporidium (63 FR 69478, December 16, 1998) 
(USEPA 1998a). The Long Term 1 Enhanced Surface Water Treatment Rule 
(LT1ESWTR) extends this requirement to small systems (67 FR 1812, 
January 14, 2002) (USEPA 2002a). Subsequent to promulgating these 
regulations, EPA has evaluated significant new data on Cryptosporidium 
infectivity, occurrence, and treatment (details in section III). These 
data indicate that current treatment requirements achieve adequate 
protection for the majority of systems, but there is a subset of 
systems with higher vulnerability to Cryptosporidium where additional 
treatment is necessary.
    Specifically, national survey data show that average 
Cryptosporidium occurrence in filtered systems is lower than previously 
estimated. However, these data also demonstrate that Cryptosporidium 
concentrations vary widely among systems, and that a fraction of 
filtered systems have relatively high levels of source water 
Cryptosporidium contamination. Based on this finding, along with new 
data suggesting that the infectivity (i.e., virulence) of 
Cryptosporidium may be substantially higher than previously understood, 
EPA has concluded that the current 2 log removal requirement does not 
provide an adequate degree of treatment in filtered systems with the 
highest source water Cryptosporidium levels. Consequently, EPA is 
proposing targeted additional treatment requirements under the LT2ESWTR 
for filtered systems with the highest Cryptosporidium risk.
    Under current regulations, unfiltered systems are not required to 
provide any treatment for Cryptosporidium. New occurrence data suggest 
that typical Cryptosporidium levels in the treated water of unfiltered 
systems are substantially higher than in the treated water of filtered 
systems. Hence, Cryptosporidium treatment by unfiltered systems is 
needed to achieve equivalent public health protection. Recent treatment 
studies have allowed EPA to develop criteria for systems to inactivate 
Cryptosporidium with ozone, ultraviolet (UV) light, and chlorine 
dioxide. As a result, EPA has concluded that it is feasible and 
appropriate to propose under the LT2ESWTR that all unfiltered systems 
treat for Cryptosporidium.
    In addition to concern with Cryptosporidium, the LT2ESWTR proposal 
is intended to ensure that systems maintain adequate protection against 
microbial pathogens as they take steps to reduce formation of 
disinfection byproducts (DBPs). Along with the LT2ESWTR, EPA is also 
developing a Stage 2 Disinfection Byproducts Rule (DBPR), which will 
further limit allowable levels of trihalomethanes and haloacetic acids. 
The proposed LT2ESWTR contains disinfection profiling and benchmarking 
requirements to ensure that microbial protection is maintained as 
systems comply with the Stage 2 DBPR. Also in the proposed LT2ESWTR are 
requirements to limit risk associated with existing uncovered finished 
water storage facilities. Uncovered storage facilities are subject to 
contamination if not properly managed or treated.
    Today's proposed LT2ESWTR reflects consensus recommendations from 
the Stage 2 Microbial and Disinfection Byproducts (M-DBP) Federal 
Advisory Committee. These recommendations are set forth in the Stage 2 
M-DBP Agreement in Principle (65 FR 83015, December 29, 2000) (USEPA 
2000a).

B. What Does the LT2ESWTR Proposal Require?

1. Treatment Requirements for Cryptosporidium
    EPA is proposing risk-targeted treatment technique requirements for 
Cryptosporidium control in filtered systems that are based on a 
microbial framework approach. Under this approach, systems that use a 
surface water or ground water under the direct influence of surface 
water (referred to collectively as surface water systems) will conduct 
source water monitoring to determine an average Cryptosporidium 
concentration. Based on monitoring results, filtered systems will be 
classified in one of four possible risk categories (bins). A filtered 
system's bin classification determines the extent of any additional 
Cryptosporidium treatment requirements beyond the requirements of 
current regulations.
    EPA expects that the majority of filtered systems will be 
classified in the Bin 1, which carries no additional treatment 
requirements. Those systems classified Bins 2-4 will be required to 
provide from 1.0 to 2.5 log of treatment (i.e., 90 to 99.7 percent 
reduction) for Cryptosporidium in addition to conventional treatment 
that complies with the IESWTR or LT1ESWTR (details in section IV.A). 
Filtered systems will meet additional Cryptosporidium treatment 
requirements by using one or more treatment or control steps from a 
``microbial toolbox'' of options (details in section IV.C). Rather than 
monitoring, filtered systems may elect to comply with the treatment 
requirements of Bin 4 directly.
    Under the proposed LT2ESWTR, all surface water systems that are not 
required to filter (i.e., unfiltered systems) must provide at least 2 
log (i.e., 99 percent) inactivation of Cryptosporidium. In addition, 
unfiltered systems will monitor for Cryptosporidium in their source 
water and must achieve at least 3 log (i.e., 99.9 percent) inactivation 
of Cryptosporidium if the mean level exceeds 0.01 oocysts/L. 
Alternatively, unfiltered systems may elect to provide 3 log 
Cryptosporidium inactivation directly, instead of monitoring. All 
requirements established under the Surface Water Treatment Rule (SWTR) 
(54 FR 27486, June 29, 1989) (USEPA 1989a) for unfiltered systems will 
remain in effect, including 3 log inactivation of Giardia lamblia and 4 
log inactivation of viruses. However, the LT2ESWTR proposal requires 
that unfiltered systems achieve their overall inactivation requirements 
using a

[[Page 47645]]

minimum of two disinfectants (details in section IV.B).
2. Disinfection Profiling and Benchmarking
    The purpose of disinfection profiling and benchmarking is to ensure 
that when a system makes a significant change to its disinfection 
practice, it does not compromise the adequacy of existing microbial 
protection. EPA established the disinfection benchmark under the IESWTR 
and LT1ESWTR for the Stage 1 M-DBP rules, and the LT2ESWTR proposal 
extends disinfection benchmark requirements to apply to the Stage 2 M-
DBP rules.
    The proposed profiling and benchmarking requirements are similar to 
those promulgated under IESWTR and LT1ESWTR. Systems that meet 
specified criteria must prepare disinfection profiles that characterize 
current levels of virus and Giardia lamblia inactivation over the 
course of one year. Systems with valid operational data from profiling 
conducted under the IESWTR or LT1ESWTR are not required to collect 
additional data. If a system that is required to prepare a profile 
proposes to make a significant change to its disinfection practice, the 
system must calculate a disinfection benchmark and must consult with 
the State regarding how the proposed change will affect the current 
benchmark (details in section IV.D).
3. Uncovered Finished Water Storage Facilities
    The proposed LT2ESWTR also includes requirements for systems with 
uncovered finished water storage facilities. The IESWTR and LT1ESWTR 
require systems to cover all new storage facilities for finished water, 
but these rules do not address existing uncovered finished water 
storage facilities. Under the LT2ESWTR proposal, systems with uncovered 
finished water storage facilities must cover the storage facility or 
treat the storage facility discharge to achieve 4 log virus 
inactivation unless the State determines that existing risk mitigation 
is adequate. Where the State makes such a determination, systems must 
develop and implement a risk mitigation plan that addresses physical 
access, surface water run-off, animal and bird wastes, and on-going 
water quality assessment (details in section IV.E).

C. Will This Proposed Regulation Apply to My Water System?

    All community and non-community water systems that use surface 
water or ground water under the direct influence of surface water are 
affected by the proposed LT2ESWTR.

II. Background

A. What Is the Statutory Authority for the LT2ESWTR?

    This section discusses the Safe Drinking Water Act (SDWA or the 
Act) sections that direct the development of the LT2ESWTR.
    The Act, as amended in 1996, requires EPA to publish a maximum 
contaminant level goal (MCLG) and promulgate a national primary 
drinking water regulation (NPDWR) with enforceable requirements for any 
contaminant that the Administrator determines may have an adverse 
effect on the health of persons, is known to occur or there is a 
substantial likelihood that the contaminant will occur in public water 
systems (PWSs) with a frequency and at levels of public health concern, 
and for which in the sole judgement of the Administrator, regulation of 
such contaminant presents a meaningful opportunity for health risk 
reduction for persons served by PWSs (section 1412 (b)(1)(A)).
    MCLGs are non-enforceable health goals, and are to be set at a 
level at which no known or anticipated adverse effect on the health of 
persons occur and which allows an adequate margin of safety (sections 
1412(b)(4) and 1412(a)(3)). EPA established an MCLG of zero for 
Cryptosporidium under the IESWTR (63 FR 69478, December 16, 1998) 
(USEPA 1998a). The Agency is not proposing any changes to the current 
MCLG for Cryptosporidium.
    The Act also requires that at the same time EPA publishes an NPDWR 
and MCLG, it must specify in the NPDWR a maximum contaminant level 
(MCL) which is as close to the MCLG as is feasible (sections 1412(b)(4) 
and 1401(1)(c)). The Agency is authorized to promulgate an NPDWR that 
requires the use of a treatment technique in lieu of establishing an 
MCL if the Agency finds that it is not economically or technologically 
feasible to ascertain the level of the contaminant (sections 
1412(b)(7)(A) and 1401(1)(C)). The Act specifies that in such cases, 
the Agency shall identify those treatment techniques that would prevent 
known or anticipated adverse effects on the health of persons to the 
extent feasible (section 1412(b)(7)(A)).
    The Agency has concluded that it is not currently economically or 
technologically feasible for PWSs to determine the level of 
Cryptosporidium in finished drinking water for the purpose of 
compliance with a finished water standard (the performance of available 
analytical methods for Cryptosporidium is described in section III.C; 
the treated water Cryptosporidium levels that the LT2ESWTR will achieve 
are described in section IV.A). Consequently, today's proposal for the 
LT2ESWTR relies on treatment technique requirements to reduce health 
risks from Cryptosporidium in PWSs.
    When proposing a NPDWR that includes an MCL or treatment technique, 
the Act requires EPA to publish and seek public comment on an analysis 
of health risk reduction and cost impacts. This includes an analysis of 
quantifiable and nonquantifiable costs and health risk reduction 
benefits, incremental costs and benefits of each alternative 
considered, the effects of the contaminant upon sensitive 
subpopulations (e.g., infants, children, pregnant women, the elderly, 
and individuals with a history of serious illness), any increased risk 
that may occur as the result of compliance, and other relevant factors 
(section 1412 (b)(3)(C)). EPA's analysis of health benefits and costs 
associated with the proposed LT2ESWTR is presented in ``Economic 
Analysis of the LT2ESWTR'' (USEPA 2003a) and is summarized in section 
VI of this preamble. However, the Act does not authorize the 
Administrator to use additional health risk reduction and cost 
considerations to establish MCL or treatment technique requirements for 
the control of Cryptosporidium (section 1412 (b)(6)(C)).
    Finally, section 1412 (b)(2)(C) of SDWA requires EPA to promulgate 
a Stage 2 Disinfectants and Disinfection Byproducts Rule within 18 
months after promulgation of the LT1ESWTR, which occurred on January 
14, 2002. Consistent with statutory requirements for risk balancing 
(section 1412(b)(5)(B)), EPA will finalize the LT2ESWTR with the Stage 
2 DBPR to ensure parallel protection from microbial and DBP risks.

B. What Current Regulations Address Microbial Pathogens in Drinking 
Water?

    This section summarizes the existing regulations that apply to 
control of pathogenic microorganisms in surface water systems. These 
rules form the baseline of regulatory protection that will be 
supplemented by the LT2ESWTR.
1. Surface Water Treatment Rule
    The SWTR (54 FR 27486, June 29, 1989) (USEPA 1989a) applies to all 
PWSs using surface water or ground water under the direct influence 
(GWUDI) of surface water as sources (Subpart H systems). It established

[[Page 47646]]

MCLGs of zero for Giardia lamblia, viruses, and Legionella, and 
includes treatment technique requirements to reduce exposure to 
pathogenic microorganisms, including: (1) Filtration, unless specified 
avoidance criteria are met; (2) maintenance of a disinfectant residual 
in the distribution system; (3) removal and/or inactivation of 3 log 
(99.9%) of Giardia lamblia and 4 log (99.99%) of viruses; (4) combined 
filter effluent turbidity of 5 nephelometric turbidity units (NTU) as a 
maximum and 0.5 NTU at 95th percentile monthly for treatment plants 
using conventional treatment or direct filtration (with separate 
standards for other filtration technologies); and (5) watershed 
protection and source water quality requirements for unfiltered 
systems.
2. Total Coliform Rule
    The Total Coliform Rule (TCR) (54 FR 27544, June 29, 1989) (USEPA 
1989b) applies to all PWSs. It established an MCLG of zero for total 
and fecal coliform bacteria, and an MCL based on the percentage of 
positive samples collected during a compliance period. Coliforms are 
used as a screen for fecal contamination and to determine the integrity 
of the water treatment process and distribution system. Under the TCR, 
no more than 5 percent of distribution system samples collected in any 
month may contain coliform bacteria (no more than 1 sample per month 
may be coliform positive in those systems that collect fewer than 40 
samples per month). The number of samples to be collected in a month is 
based on the number of people served by the system.
3. Interim Enhanced Surface Water Treatment Rule
    The IESWTR (63 FR 69477, December 16, 1998) (USEPA 1998a) applies 
to PWSs serving at least 10,000 people and using surface water or GWUDI 
sources. Key provisions established by the IESWTR include the 
following: (1) An MCLG of zero for Cryptosporidium; (2) Cryptosporidium 
removal requirements of 2 log (99 percent) for systems that filter; (3) 
strengthened combined filter effluent turbidity performance standards 
of 1.0 NTU as a maximum and 0.3 NTU at the 95th percentile monthly for 
treatment plants using conventional treatment or direct filtration; (4) 
requirements for individual filter turbidity monitoring; (5) 
disinfection benchmark provisions to assess the level of microbial 
protection provided as facilities take steps to comply with new DBP 
standards; (6) inclusion of Cryptosporidium in the definition of GWUDI 
and in the watershed control requirements for unfiltered public water 
systems; (7) requirements for covers on new finished water storage 
facilities; and (8) sanitary surveys for all surface water systems 
regardless of size.
    The IESWTR was developed in conjunction with the Stage 1 
Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR) (63 FR 
69389; December 16, 1998) (USEPA 1998b), which reduced allowable levels 
of certain DBPs, including trihalomethanes, haloacetic acids, chlorite, 
and bromate.
4. Long Term 1 Enhanced Surface Water Treatment Rule
    The LT1ESWTR (67 FR 1812, January 14, 2002) (USEPA 2002a) builds 
upon the microbial control provisions established by the IESWTR for 
large systems, through extending similar requirements to small systems. 
The LT1ESWTR applies to PWSs using surface water or GWUDI as sources 
that serve fewer than 10,000 people. Like the IESWTR, the LT1ESWTR 
established the following: 2 log (99 percent) Cryptosporidium removal 
requirements for systems that filter; individual filter turbidity 
monitoring and more stringent combined filter effluent turbidity 
standards for conventional and direct filtration plants; disinfection 
profiling and benchmarking; inclusion of Cryptosporidium in the 
definition of GWUDI and in the watershed control requirements for 
unfiltered systems; and the requirement that new finished water storage 
facilities be covered.
5. Filter Backwash Recycle Rule
    EPA promulgated the Filter Backwash Recycling Rule (FBRR) (66 FR 
31085, June 8, 2001) (USEPA 2001a) to increase protection of finished 
drinking water supplies from contamination by Cryptosporidium and other 
microbial pathogens. The FBRR requirements will reduce the potential 
risks associated with recycling contaminants removed during the 
filtration process. The FBRR provisions apply to all systems that 
recycle, regardless of population served. In general, the provisions 
include the following: (1) Recycling systems must return certain 
recycle streams prior to the point of primary coagulant addition unless 
the State specifies an alternative location; (2) direct filtration 
systems recycling to the treatment process must provide detailed 
recycle treatment information to the State; and (3) certain 
conventional systems that practice direct recycling must perform a one-
month, one-time recycling self assessment.

C. What Public Health Concerns Does This Proposal Address?

    This section presents the basis for the public health concern 
associated with Cryptosporidium in drinking water by summarizing 
information on Cryptosporidium health effects and outbreaks. This is 
followed by a description of the specific areas of public health 
concern that remain after implementation of the IESWTR and LT1ESWTR and 
that are addressed in the LT2ESWTR proposal. More detailed information 
about Cryptosporidium health effects may be found in the following 
criteria documents: Cryptosporidium: Human Health Criteria Document 
(USEPA 2001b), Cryptosporidium: Drinking Water Advisory (USEPA 2001c), 
and Cryptosporidium: Risks for Infants and Children (USEPA 2001d).
1. Introduction
    While modern water treatment systems have substantially reduced 
waterborne disease incidence, drinking water contamination remains a 
significant health risk management challenge. EPA's Science Advisory 
Board in 1990 cited drinking water contamination, particularly 
contamination by pathogenic microorganisms, as one of the most 
important environmental risks (USEPA 1990). This risk is underscored by 
information from the Centers for Disease Control and Prevention (CDC) 
which indicates that between 1980 and 1998 a total of 419 outbreaks 
associated with drinking water were reported, with greater than 511,000 
estimated cases of disease. A number of agents were implicated in these 
outbreaks, including viruses, bacteria, and protozoa, as well as 
several chemicals (Craun and Calderon 1996, Levy et al. 1998, Barwick 
et al. 2000). The majority of cases were associated with surface water, 
and specifically with the 1993 Cryptosporidium outbreak in Milwaukee, 
WI with an estimated 403,000 cases (Mac Kenzie et al. 1994). A recent 
study by McDonald et al. (2001), which used blood samples from 
Milwaukee children collected during and after the 1993 outbreak, 
suggests that Cryptosporidium infection, including asymptomatic 
infection, was more widespread than might be inferred from the illness 
estimates by Mac Kenzie et al. (1994).
    It is important to note that the number of identified and reported 
outbreaks in the CDC database is believed to substantially understate 
the actual incidence of waterborne disease outbreaks and cases (Craun 
and

[[Page 47647]]

Calderon 1996, National Research Council 1997). This under reporting is 
due to a number of factors. Many people experiencing gastrointestinal 
illness do not seek medical attention. Where medical attention is 
provided, the pathogenic agent may not be identified through routine 
testing. Physicians often lack sufficient information to attribute 
gastrointestinal illness to any specific origin, such as drinking 
water, and few States have an active outbreak surveillance program. 
Consequently, outbreaks are often not recognized in a community or, if 
recognized, are not traced to a drinking water source.
    In addition, an unknown but probably significant portion of 
waterborne disease is endemic (i.e. isolated cases not associated with 
an outbreak) and, thus, is even more difficult to recognize. The 
Economic Analysis for the proposed LT2ESWTR (USEPA 2003a) uses data on 
Cryptosporidium occurrence, infectivity, and treatment to estimate the 
baseline endemic incidence of cryptosporidiosis attributable to 
drinking water, as well as the reductions projected as a result of this 
rule.
    Most waterborne pathogens cause gastrointestinal illness with 
diarrhea, abdominal discomfort, nausea, vomiting, and other symptoms. 
The effects of waterborne disease are usually acute, resulting from a 
single or small number of exposures. Such illnesses are generally of 
short duration in healthy people. However, some pathogens, including 
Giardia lamblia and Cryptosporidium, may cause disease lasting weeks or 
longer in otherwise healthy individuals, though this is not typical for 
Cryptosporidium. Waterborne pathogens also cause more serious disorders 
such as hepatitis, peptic ulcers, myocarditis, paralysis, 
conjunctivitis, swollen lymph glands, meningitis, and reactive 
arthritis, and have been associated with diabetes, encephalitis, and 
other diseases (Lederberg 1992).
    There are populations that are at greater risk from waterborne 
disease. These sensitive subpopulations include children (especially 
infants), the elderly, the malnourished, pregnant women, the disease 
impaired (e.g., diabetes, cystic fibrosis), and a broad category of 
those with compromised immune systems, such as AIDS patients, those 
with autoimmune disorders (e.g., rheumatoid arthritis, lupus 
erythematosus, multiple sclerosis), transplant recipients, and those on 
chemotherapy (Rose 1997). This sensitive segment represents almost 20% 
of the population in the United States (Gerba et al. 1996). The 
severity and duration of illness is often greater in sensitive 
subpopulations than in healthy individuals, and in a small percentage 
of such cases, death may result.
2. Cryptosporidium Health Effects and Outbreaks
    Cryptosporidium is a protozoan parasite that exists in warm-blooded 
hosts and, upon excretion, may survive for months in the environment 
(Kato et al., 2001). Ingestion of Cryptosporidium can lead to 
cryptosporidiosis, a gastrointestinal illness. Transmission of 
cryptosporidiosis often occurs through consumption of feces 
contaminated food or water, but may also result from direct or indirect 
contact with infected persons or animals (Casemore 1990). Surveys 
(described in Section III) indicate that Cryptosporidium is common in 
surface waters used as drinking water supplies. Sources of 
Cryptosporidium contamination include animal agriculture, wastewater 
treatment plant discharges, slaughterhouses, birds, wild animals, and 
other sources of fecal matter.
    EPA is particularly concerned about Cryptosporidium because, unlike 
pathogens such as bacteria and most viruses, Cryptosporidium oocysts 
are highly resistant to standard disinfectants like chlorine and 
chloramines. Consequently, control of Cryptosporidium in most treatment 
plants is dependent on physical removal processes. Finished water 
monitoring data indicate that Cryptosporidium is sometimes present in 
filtered, treated drinking water (LeChevallier et al. 1991; Aboytes et 
al. 2002). Moreover, as noted later, many of the individuals sickened 
by waterborne outbreaks of cryptosporidiosis were served by filtered 
surface water supplies (Solo-Gabriele and Neumeister, 1996). In some 
cases, these outbreaks were attributed to treatment deficiencies, while 
in other cases the cause was unidentified (see Table II-1).
    These data suggest that surface water systems that filter and 
disinfect may still be vulnerable to Cryptosporidium, depending on the 
source water quality and treatment effectiveness. Today's proposed rule 
addresses concern with passage of Cryptosporidium through physical 
removal processes during water treatment, as well as in systems lacking 
filtration.
    a. Health effects. Cryptosporidium infection is characterized by 
mild to severe diarrhea, dehydration, stomach cramps, and/or a slight 
fever. Symptoms typically last from several days to two weeks, though 
in a small percentage of cases, the symptoms may persist for months or 
longer in otherwise healthy individuals. Human feeding studies have 
demonstrated that a low dose of Cryptosporidium parvum (C. parvum) is 
sufficient to cause infection in healthy adults (DuPont et al. 1995, 
Chappell et al. 1999, Messner et al. 2001). Studies of immunosuppressed 
adult mice have demonstrated that a single viable oocyst can induce 
patent C. parvum infections (Yang et al. 2000).
    There is evidence that an immune response to Cryptosporidium 
exists, but the degree and duration of this immunity is not well 
characterized. In a study by Chappell et al. (1999), individuals with a 
blood serum antibody (IgG), which can develop from exposure to C. 
parvum, demonstrated immunity to low doses of oocysts. The 
investigators found the ID50 dose (i.e., dose that infects 50% of the 
challenged population) of one C. parvum isolate for adult volunteers 
who had pre-existing serum IgG to be 1,880 oocysts in comparison to 132 
oocysts for individuals reported as serologically negative. However, 
the implications of these data for studies of Cryptosporidium 
infectivity are unclear. Earlier work did not observe a correlation 
between the development of antibodies after Cryptosporidium exposure 
and subsequent protection from illness (Okhuysen et al. 1998). A 
subsequent investigation by Muller et al. (2001) observed serological 
responses to Cryptosporidium antigens in samples from individuals 
reported by Chappel et al. as serologically negative.
    Cryptosporidium parvum was first recognized as a human pathogen in 
1976 (Juranek 1995). Cases of illness from Cryptosporidium were rarely 
reported until 1982 when documented disease incidence increased due to 
the AIDS epidemic (Current 1983). As laboratory diagnostic techniques 
improved during subsequent years, outbreaks among immunocompetent 
persons were recognized as well. Human, cattle, dog and deer types of 
C. parvum have been found in healthy individuals (Ong et al. 2002, 
Morgan-Ryan et al. 2002). Other Cryptosporidium species (C. felis, C. 
meleagridis, and possibly C. muris) have infected healthy individuals, 
primarily children (Xiao et al. 2001, Chalmers et al. 2002, Katsumata 
et al. 2000). Cross-species infection occurs. The human type of C. 
parvum (now named C. hominis (Morgan-Ryan et al. 2002)) has infected a 
dugong and monkeys (Spano et al. 1998). The cattle type of C. parvum 
infects humans, wild animals, and other livestock, such as sheep, goats 
and deer (Ong et al. 2002).
    As noted earlier, there are sensitive populations that are at 
greater risk from pathogenic microorganisms.

[[Page 47648]]

Cryptosporidiosis symptoms in immunocompromised subpopulations are much 
more severe, including debilitating voluminous diarrhea that may be 
accompanied by severe abdominal cramps, weight loss, and low grade 
fever (Juranek 1995). Mortality is a significant threat to the 
immunocompromised infected with Cryptosporidium:

    the duration and severity of the disease are significant: 
whereas 1 percent of the immunocompetent population may be 
hospitalized with very little risk of mortality, Cryptosporidium 
infections are associated with a high rate of mortality in the 
immunocompromised (Rose 1997)

    A follow-up study of the 1993 Milwaukee, WI outbreak reported that 
at least 50 Cryptosporidium-associated deaths occurred among the 
severely immunocompromised (Hoxie et al. 1997).
    b. Waterborne cryptosporidiosis outbreaks. Cryptosporidium has 
caused a number of waterborne disease outbreaks since 1984 when the 
first one was reported in the U.S. Table II-1 lists reported outbreaks 
in community water systems (CWS) and non-community water systems 
(NCWS). Between 1984--1998, nine outbreaks caused by Cryptosporidium 
were reported in the U.S. with approximately 421,000 cases associated 
cases of illness (CDC 1993, 1996, 1998, 2000, and 2001). Solo-Gabriele 
and Neumeister (1996) characterized water supplies associated with U.S. 
outbreaks of cryptosporidiosis. They determined that almost half of the 
outbreaks were associated with ground water (untreated or chlorinated 
springs and wells), but that the majority of affected individuals were 
served by filtered surface water supplies (rivers and lakes). They 
found that during outbreaks involving treated spring or well water, the 
chlorination systems were apparently operating satisfactorily, with a 
measurable chlorine residual.
    Although the occurrence of Cryptosporidium in U.S. drinking water 
supplies has been substantiated by data collected during outbreak 
investigations, the source and density of oocysts associated with the 
outbreak have not always been detected or reported. Furthermore, 
because of limitations and uncertainties of the immunofluorescence 
assay (IFA) method used in earlier studies, negative results in source 
or finished water during these outbreaks do not necessarily mean that 
there were no oocysts in the water at the time of sampling.

               Table II-1.--Outbreaks Caused by Cryptosporidium in Public Water Systems: 1984-1998
----------------------------------------------------------------------------------------------------------------
             Year                    State           Cases           System        Deficiency        Source
----------------------------------------------------------------------------------------------------------------
1984.........................  TX                         117  CWS                          3   Well.
1987.........................  GA                      13,000  CWS                          3   River.
1991.........................  PA                         551  NCWS                         3   Well.
1992.........................  OR                 [dagger][da  CWS                          3   Spring.
                                                        gger]
1992.........................  OR                 [dagger][da  CWS                          3   River.
                                                        gger]
1993.........................  NV                         103  CWS                          5   Lake.
1993.........................  WI                     403,000  CWS                          3   Lake.
1994.........................  WA                         134  CWS                          2   Well.
1998.........................  TX                       1,400  CWS                          3   Well.
----------------------------------------------------------------------------------------------------------------
[dagger][dagger] =Total estimated cases were 3,000. The locations were nearby and cases overlapped in time
  Definitions of deficiencies = (1) untreated surface water; (2) untreated ground water; (3) treatment
  deficiency (e.g., temporary interruption of disinfection, chronically inadequate disinfection, and inadequate
  or no filtration); (4) distribution system deficiency (e.g., cross connection, contamination of water mains
  during construction or repair, and contamination of a storage facility); and (5) unknown or miscellaneous
  deficiency.

3. Remaining Public Health Concerns Following the IESWTR and LT1ESWTR
    This section presents the areas of remaining public health concern 
following implementation of the IESWTR and LT1ESWTR that EPA proposes 
to address in the LT2ESWTR. These are as follows: (a) Adequacy of 
physical removal to control Cryptosporidium and the need for risk based 
treatment requirements; (b) control of Cryptosporidium in unfiltered 
systems; and (c) uncovered finished water storage facilities.
    EPA recognized each of these issues as a potential public health 
concern during development of the IESWTR, but could not address them at 
that time due to the absence of key data. Accordingly, this section 
begins with a description of how EPA considered these issues during 
development of the IESWTR, including the data gaps that were identified 
at that time. This is followed by a statement of the extent to which 
new information has filled these data gaps, thereby allowing EPA to 
address these public health concerns in the LT2ESWTR proposal.
    a. Adequacy of physical removal to control Cryptosporidium and the 
need for risk based treatment requirements. A question that received 
significant consideration during development of the IESWTR is whether 
physical removal by filtration plants provides adequate protection 
against Cryptosporidium in drinking water, or whether certain systems 
should be required to provide inactivation of Cryptosporidium based on 
source water pathogen levels. As discussed in the proposal, notice of 
data availability (NODA), and final IESWTR, EPA and stakeholders 
concluded that data available during IESWTR development were not 
adequate to support risk based inactivation requirements for 
Cryptosporidium. However, the Agency maintained that a risk based 
approach to Cryptosporidium control would be considered for the 
LT2ESWTR when data collected under the Information Collection Rule were 
available and other critical information needs had been addressed.
    The IESWTR proposal (59 FR 38832, July 29, 1994) (USEPA 1994) 
included two treatment alternatives, labeled B and C, that specifically 
addressed Cryptosporidium. Under Alternative B, the level of required 
treatment would be based on the density of Cryptosporidium in the 
source water. The proposal noted concerns with this approach, though, 
due to uncertainty in the risk associated with Cryptosporidium and the 
feasibility of achieving higher treatment levels through disinfection. 
Consequently, EPA also proposed Alternative C, which would require 2 
log (99%) removal of Cryptosporidium by filtration. This was based on 
the determination that 2 log Cryptosporidium removal is feasible using 
conventional treatment.
    In the 1996 Information Collection Rule (61 FR 24354, May 14, 1996) 
(USEPA 1996a), EPA concluded that the analytical method prescribed for 
measuring Cryptosporidium was

[[Page 47649]]

adequate for making national occurrence estimates, but would not 
suffice for making site specific source water density estimates. This 
finding further contributed to the rationale supporting Alternative C 
under the proposed IESWTR.
    The NODA for the IESWTR (62 FR 59498, Nov. 3, 1997) (USEPA 1997a) 
presented the recommendations of the Stage 1 MDBP Federal Advisory 
Committee for the IESWTR. As stated in the NODA, the Committee engaged 
in extensive discussions regarding the adequacy of relying solely on 
physical removal to control Cryptosporidium and the need for 
inactivation. There was an absence of consensus on whether it was 
possible at that time to adequately measure Cryptosporidium 
inactivation efficiencies for various disinfection technologies. This 
was a significant impediment to addressing inactivation in the IESWTR. 
However, the Committee recognized that inactivation requirements may be 
necessary under future regulatory scenarios, as shown by the following 
consensus recommendation from the Stage 1 MDBP Agreement in Principle:

    EPA should issue a risk based proposal of the Final Enhanced 
Surface Water Treatment Rule for Cryptosporidium embodying the 
multiple barrier approach (e.g., source water protection, physical 
removal, inactivation, etc.), including, where risks suggest 
appropriate, inactivation requirements (62 FR 59557, Nov. 3, 1997) 
(USEPA 1997a).

    The preamble to the final IESWTR (63 FR 69478, Dec. 16, 1998) 
(USEPA 1998a) states that EPA was unable to consider the proposed 
Alternative B (treatment requirements for Cryptosporidium based on 
source water occurrence levels) for the IESWTR because occurrence data 
from the Information Collection Rule survey and related analysis were 
not available in time to meet the statutory promulgation deadline. The 
Agency affirmed, though, that further control of Cryptosporidium would 
be addressed in the LT2ESWTR.
    In today's notice, EPA is proposing a risk based approach for 
control of Cryptosporidium in drinking water. Under this approach, the 
required level of additional Cryptosporidium treatment relates to the 
source water pathogen density. EPA believes many of the data gaps that 
prevented the adoption of this approach under the IESWTR have been 
addressed. As described in Section III of this preamble, information on 
Cryptosporidium occurrence from the Information Collection Rule and 
Information Collection Rule Supplemental Surveys, along with new data 
on Cryptosporidium infectivity, have provided EPA with a better 
understanding of the magnitude and distribution of risk for this 
pathogen. Improved analytical methods allow for a more accurate 
assessment of source water Cryptosporidium levels, and recent 
disinfection studies with UV, ozone, and chlorine dioxide provide the 
technical basis to support Cryptosporidium inactivation requirements.
    b. Control of Cryptosporidium in unfiltered systems. There is 
particular concern about Cryptosporidium in the source waters of 
unfiltered systems because this pathogen has been shown to be resistant 
to conventional disinfection practices. In the IESWTR, EPA extended 
watershed control requirements for unfiltered systems to include the 
control of Cryptosporidium. EPA did not establish Cryptosporidium 
treatment requirements for unfiltered systems because available data 
suggested an equivalency of risk in filtered and unfiltered systems. 
This is described in the final IESWTR as follows:

it appears that unfiltered water systems that comply with the source 
water requirements of the SWTR have a risk of cryptosporidiosis 
equivalent to that of a water system with a well operated filter 
plant using a water source of average quality (63 FR 69492, Dec. 16, 
1998) (USEPA 1998a)

    The Agency noted that data from the Information Collection Rule 
would provide more information on Cryptosporidium levels in filtered 
and unfiltered systems, and that Cryptosporidium treatment requirements 
would be re-evaluated when these data became available.
    In today's notice, EPA is proposing Cryptosporidium inactivation 
requirements for unfiltered systems. These proposed requirements stem 
from an assessment of Cryptosporidium source water occurrence in both 
filtered and unfiltered systems using data from the Information 
Collection Rule and other surveys, as described in Section III of this 
preamble. These new data do not support the finding described in the 
IESWTR of equivalent risk in filtered and unfiltered systems. Rather, 
Cryptosporidium treatment by unfiltered systems is necessary to achieve 
a finished water risk level equivalent to that of filtered systems. In 
addition, the development of Cryptosporidium inactivation criteria for 
UV, ozone, and chlorine dioxide in the LT2ESWTR has made it feasible 
for unfiltered systems to provide Cryptosporidium treatment.
    c. Uncovered finished water storage facilities. In the IESWTR 
proposal, EPA solicited comment on a requirement that systems cover 
finished water storage facilities to reduce the potential for 
contamination by pathogens and hazardous chemicals. Potential sources 
of contamination to uncovered storage facilities include airborne 
chemicals, runoff, animal carcasses, animal or bird droppings, and 
growth of algae and other aquatic organisms (59 FR 38832, July 29, 
1994) (USEPA 1994).
    The final IESWTR established a requirement to cover all new storage 
facilities for finished water for which construction began after 
February 16, 1999 (63 FR 69493, Dec. 16, 1998) (USEPA 1998a). In 
preamble to the final IESWTR, EPA described future regulation of 
existing uncovered finished water storage facilities as follows:

    EPA needs more time to collect and analyze additional 
information to evaluate regulatory impacts on systems with existing 
uncovered reservoirs on a national basis . . . EPA will further 
consider whether to require the covering of existing reservoirs 
during the development of subsequent microbial regulations when 
additional data and analysis to develop the national costs of 
coverage are available.

    EPA continues to be concerned about contamination resulting from 
uncovered finished water storage facilities, particularly the potential 
for virus contamination via bird droppings, and now has sufficient data 
to estimate national cost implications for various regulatory control 
strategies. Therefore, EPA is proposing control measures for all 
systems with uncovered finished water storage facilities in the 
LT2ESWTR. New data and proposed requirements are described in section 
IV.E of this preamble.

D. Federal Advisory Committee Process

    In March 1999, EPA reconvened the M-DBP Federal Advisory Committee 
to develop recommendations for the Stage 2 DBPR and LT2ESWTR. The 
Committee consisted of organizational members representing EPA, State 
and local public health and regulatory agencies, local elected 
officials, Indian Tribes, drinking water suppliers, chemical and 
equipment manufacturers, and public interest groups. Technical support 
for the Committee's discussions was provided by a technical workgroup 
established by the Committee at its first meeting. The Committee's 
activities resulted in the collection and evaluation of substantial new 
information related to key elements for both rules. This included new 
data on pathogenicity, occurrence, and treatment of microbial 
contaminants, specifically including Cryptosporidium, as well as new 
data on DBP health risks, exposure, and control. New information 
relevant to the

[[Page 47650]]

LT2ESWTR is summarized in Section III of this proposal.
    In September 2000, the Committee signed an Agreement in Principle 
reflecting the consensus recommendations of the group. The Agreement 
was published in a December 29, 2000 Federal Register notice (65 FR 
83015, December 29, 2000) (USEPA 2000a). The Agreement is divided into 
Parts A & B. The entire Committee reached consensus on Part A, which 
contains provisions that directly apply to the Stage 2 DBPR and 
LT2ESWTR. The full Committee, with the exception of one member, agreed 
to Part B, which has recommendations for future activities by EPA in 
the areas of distribution systems and microbial water quality criteria.
    The Committee reached agreement on the following major issues 
discussed in this notice and the proposed Stage 2 DBPR:
    LT2ESWTR: (1) Additional Cryptosporidium treatment based on source 
water monitoring results; (2) Filtered systems that must comply with 
additional Cryptosporidium treatment requirements may choose from a 
``toolbox'' of treatment and control options; (3) Reduced monitoring 
burden for small systems; (4) Future monitoring to confirm source water 
quality assessments; (5) Cryptosporidium inactivation by all unfiltered 
systems; (6) Unfiltered systems meet overall inactivation requirements 
using a minimum of 2 disinfectants; (7) Development of criteria and 
guidance for UV disinfection and other toolbox options; (8) Cover or 
treat existing uncovered finished water reservoirs (i.e., storage 
facilities) or implement risk mitigation plans.
    Stage 2 DBPR: (1) Compliance calculation for total trihanomethanes 
(TTHM) and five haloacetic acids (HAA5) revised from a running annual 
average (RAA) to a locational running annual average (LRAA); (2) 
Compliance carried out in two phases of the rule; (3) Performance of an 
Initial Distribution System Evaluation; (4) Continued importance of 
simultaneous compliance with DBP and microbial regulations; (5) 
Unchanged MCL for bromate.

III. New Information on Cryptosporidium Health Risks and Treatment

    The purpose of this section is to describe information related to 
health risks and treatment of Cryptosporidium in drinking water that 
has become available since EPA developed the IESWTR. Much of this 
information was evaluated by the Stage 2 M-DBP Federal Advisory 
Committee when considering whether and to what degree existing 
microbial standards should be revised to protect public health. It 
serves as a basis for the recommendations made by the Advisory 
Committee and for provisions in today's proposed rule. This section 
begins with an overview of critical factors that EPA considers when 
evaluating regulation of microbial pathogens. New information is then 
presented on three key topics: Cryptosporidium infectivity, occurrence, 
and treatment.

A. Overview of Critical Factors for Evaluating Regulation of Microbial 
Pathogens

    When proposing a national primary drinking water regulation that 
includes a maximum contaminant level or treatment technique, SDWA 
requires EPA to analyze the health risk reduction benefits and costs 
likely to result from alternative regulatory levels that are being 
considered. For assessing risk, EPA follows the paradigm described by 
the National Academy of Science (NRC, 1983) which involves four steps: 
(1) Hazard identification, (2) dose-response assessment, (3) exposure 
assessment, and (4) risk characterization. The application of these 
steps to microbial pathogens is briefly described in this section, 
followed by a summary of how EPA estimates the health benefits and 
costs of regulatory alternatives.
    Hazard identification for microbial pathogens is a description of 
the nature, severity, and duration of the health effects stemming from 
infection. Under SDWA, EPA must consider health effects on the general 
population and on subpopulations that are at greater risk of adverse 
health effects. See section II.C.2 of this preamble for health effects 
associated with Cryptosporidium.
    Dose-response assessment with microorganisms is commonly termed 
infectivity and is a description of the relationship between the number 
of pathogens ingested and the probability of infection. Information on 
Cryptosporidium infectivity is presented in section III.B of this 
preamble.
    Exposure to microbial pathogens in drinking water is generally a 
function of the concentration of the pathogen in finished water and the 
volume of water ingested (exposure also occurs through secondary routes 
involving infected individuals). Because it is difficult to directly 
measure pathogens at the low levels typically present in finished 
water, EPA's information on pathogen exposure is primarily derived from 
surveys of source water occurrence. EPA estimates the concentration of 
pathogens in treated water by combining source water pathogen 
occurrence data with information on the performance of treatment plants 
in reducing pathogen levels. Data on the occurrence of Cryptosporidium 
are described in section III.C of this preamble and in Occurrence and 
Exposure Assessment for the LT2ESWTR (USEPA 2003b). Cryptosporidium 
treatment studies are described in section III.D of this preamble.
    Risk characterization is the culminating step of the risk 
assessment process. It is a description of the nature and magnitude of 
risk, and characterizes strengths, weaknesses, and attendant 
uncertainties of the assessment. EPA's risk characterization for 
Cryptosporidium is described in Economic Analysis for the LT2ESWTR 
(USEPA 2003a).
    Estimating the health benefits and costs that would result from a 
new regulatory requirement involves a number of steps, including 
evaluating the efficacy and cost of treatment strategies to reduce 
exposure to the contaminant, forecasting the number of systems that 
would implement different treatment strategies to comply with the 
regulatory standard, and projecting the reduction in exposure to the 
contaminant and consequent health risk reduction benefits stemming from 
regulatory compliance. EPA's estimates of health benefits and costs 
associated with the proposed LT2ESWTR are presented in Economic 
Analysis for the LT2ESWTR (USEPA 2003a) and are summarized in section 
VI of this preamble.

B. Cryptosporidium Infectivity

    This section presents information on the infectivity of 
Cryptosporidium oocysts. Infectivity relates the probability of 
infection by Cryptosporidium with the number of oocysts that a person 
ingests, and it is used to predict the disease burden associated with 
different Cryptosporidium levels in drinking water. Information on 
Cryptosporidium infectivity comes from dose-response studies where 
healthy human subjects ingest different numbers of oocysts and are 
subsequently evaluated for signs of infection and illness.
    Data from a human dose-response study of one Cryptosporidium 
isolate (the IOWA study, conducted at the University of Texas-Houston 
Health Science Center) had been published prior to the IESWTR (DuPont 
et al. 1995). Following IESWTR promulgation, a study of two additional 
isolates (TAMU and UCP) was completed and published (Okhuysen et al. 
1999). This study also presented a

[[Page 47651]]

reanalysis of the IOWA study results. As described in more detail later 
in this section, this new study indicates that the infectivity of 
Cryptosporidium oocysts varies over a wide range. The UCP oocysts 
appeared less infective than those of the IOWA study while the TAMU 
oocysts were much more infective. Although the occurrence of these 
isolates among environmental oocysts is unknown, a meta-analysis of 
these data conducted by EPA suggests the overall infectivity of 
Cryptosporidium may be significantly greater than was estimated for the 
IESWTR (USEPA 2003a).
    This section begins with a description of the infectivity data 
considered for the IESWTR. This is followed by a presentation of 
additional data that have been evaluated for the proposed LT2ESWTR and 
a characterization of the significance of these new data.
1. Cryptosporidium Infectivity Data Evaluated for IESWTR
    Data from the IOWA study (DuPont et al. 1995) were evaluated for 
the IESWTR. In that study, 29 individuals were given single doses 
ranging from 30 oocysts to 1 million oocysts. This oocyst isolate was 
originally obtained from a naturally infected calf. Seven persons 
received doses above 500, and all were infected. Eleven of the twenty 
two individuals receiving doses of 500 or fewer were classified as 
infected based on oocysts detected in stool samples.
    The IOWA study data were analyzed using an exponential dose-
response model established by Haas et al. (1996) for Cryptosporidium:

Probability {Infection / Dose{time}  =
 1-e -Dose/k
    Based on the maximum likelihood estimate of k (238), the 
probability of infection from ingesting a single oocyst (1/k) is 
approximately 0.4% (4 persons infected for every 1,000 who each ingest 
one oocyst). Based on the same estimate, the dose at which 50% of 
persons become infected (known as the median infectious dose or ID50) 
is 165.
2. New Data on Cryptosporidium Infectivity
    A study of two additional Cryptosporidium isolates was conducted at 
the University of Texas-Houston Health Science Center (Okhuysen et al. 
1999). One of the isolates (UCP) was originally collected from 
naturally infected calves. The other isolate (TAMU) was originally 
collected from a veterinary student who became infected during necropsy 
on an infected foal.
    The TAMU and UCP studies were conducted with 14 and 17 subjects, 
respectively. Because thousands of oocysts per gram of stool can go 
undetected, researchers elected to use both stool test results and 
symptoms as markers of infection (only stool test results had been used 
for the IOWA study). Under this definition, two additional IOWA 
subjects were regarded as having been infected. As shown in Table III-
1, all but two of the TAMU subjects were presumed infected and all but 
six of the UCP subjects were presumed infected following ingestion of 
the indicated oocyst doses.

    Table III-1.--Cryptosporidium Parvum Infectivity in Healthy Adult
                               Volunteers
------------------------------------------------------------------------
                                                 Number of      Number
    Isolate and dose ( of oocysts)       subjects     infected
                                                    \1\          \1\
------------------------------------------------------------------------
IOWA:
  30..........................................            5            2
  100.........................................            8            4
  300.........................................            3            2
  500.........................................            6            5
  1,000.......................................            2            2
  10,000......................................            3            3
  100,000.....................................            1            1
  1,000,000...................................            1            1
TAMU:
    10........................................            3            2
    30........................................            3            2
    100.......................................            3            3
    500.......................................            5            5
UCP:
    500.......................................            5            3
    1,000.....................................            3            2
    5,000.....................................            5            2
    10,000....................................            4           4
------------------------------------------------------------------------
\1\ The two right columns list the number of subjects belonging to each
  category.

    EPA conducted a meta-analysis of these results in which the three 
isolates were considered as a random sample (of size three) from a 
larger population of environmental oocysts (Messner et al. 2001). This 
meta analysis was reviewed by the Science Advisory Board (SAB). In 
written comments from a December 2001 meeting of the Drinking Water 
Committee, SAB members recommended the following: (1) two assumed 
infectivity distributions (of parameter r = 1/k as logit normal and 
logit-t) should be used in order to characterize uncertainty and (2) 
EPA should consider excluding the UCP data set because it seems to be 
an outlier (see Section VII.K). In response, EPA has used the two 
recommended distributions for infectivity and has conducted the meta-
analysis both with and without the UCP data due to uncertainty about 
whether it is appropriate to exclude these data.
    Table III-2 presents meta-analysis estimates of the probability of 
infection given one oocyst ingested. Results are shown for the four 
different analysis conditions (log normal and log-t distributions; with 
and without UCP data) as well as a combined result derived by sampling 
equally from each distribution. A more complete description of the 
infectivity analysis is provided in Economic Analysis for the LT2ESWTR 
(USEPA 2003a).

       Table III-2.--Risk of Infection, Given One Oocyst Ingested
------------------------------------------------------------------------
              Basis for analysis                     Probability of
-----------------------------------------------   infection, one oocyst
                                                        ingested
                                               -------------------------
         Studies used           Distributional                   80%
                                    model           Mean       Credible
                                                               interval
------------------------------------------------------------------------
IOWA, TAMU, and UCP..........  Normal.........         0.07   0.007-0.19
IOWA, TAMU, and UCP..........  Student's t             0.09   0.015-0.20
                                (3df) \1\.
IOWA and TAMU................  Normal.........         0.09   0.011-0.23
IOWA and TAMU................  Student's t             0.10   0.014-0.25
                                (3df) \1\.
                                               --------------
      Equal Mix of the Four    ...............         0.09  0.011-0.22
       Above.
------------------------------------------------------------------------
\1\ Student's t distribution with 3 degrees of freedom (3df).


[[Page 47652]]

    The results in Table III-2 show that the mean probability of 
infection from ingesting a single infectious oocyst ranges from 7% to 
10% depending on the assumptions used. In comparison, the best estimate 
in the IESWTR of this probability was 0.4%, based on the IOWA isolate 
alone, and using the earlier definition of infection. Thus, these data 
suggest that both the range and magnitude of Cryptosporidium 
infectivity is higher than was estimated in the final IESWTR.
    It should be noted that although significantly more data on 
Cryptosporidium infectivity are available now than when EPA established 
the IESWTR, there remains uncertainty about this parameter in several 
areas. It is unknown how well the oocysts used in the feeding studies 
represent Cryptosporidium naturally occurring in the environment, and 
the analyses do not fully account for variability in host 
susceptibility and the effect of previous infections. Furthermore, the 
sample sizes are relatively small, and the confidence bands on the 
estimates span more than an order of magnitude. Another limitation is 
that none of the studies included doses below 10 oocysts, while when 
people ingest oocysts in drinking water it is usually a single oocyst.
3. Significance of New Infectivity Data
    The new infectivity data reveal that oocysts vary greatly in their 
ability to infect human hosts. Moreover, due to this variability and 
the finding of a highly infectious isolate, TAMU, the overall 
population of oocysts appears to be more infective than assumed for the 
IESWTR. The meta-analysis described earlier indicates the probability 
of infection at low Cryptosporidium concentrations may be about 20 
times as great as previously estimated (which was based on the IOWA 
isolate alone and using the earlier definition of infection (stool-
confirmed infections)).

C. Cryptosporidium Occurrence

    This section presents information on the occurrence of 
Cryptosporidium oocysts in drinking water sources. Occurrence 
information is important because it is used in assessing the risk 
associated with Cryptosporidium in both filtered and unfiltered 
systems, as well as in estimating the costs and benefits of the 
proposed LT2ESWTR.
    For the IESWTR, EPA had no national survey data and relied instead 
on several studies that were local or regional. Those data suggested 
that a typical (median) filtered surface water source had approximately 
2 Cryptosporidium oocysts per liter, while a typical unfiltered surface 
water source had about 0.01 oocysts per liter, a difference of two 
orders of magnitude.
    Subsequent to promulgating the IESWTR, EPA obtained data from two 
national surveys: the Information Collection Rule and the Information 
Collection Rule Supplemental Surveys (ICRSS). These surveys were 
designed to provide improved estimates of occurrence on a national 
basis. As described in more detail later in this section, the 
Information Collection Rule and ICRSS results show three main 
differences in comparison to Cryptosporidium occurrence data used for 
the IESWTR:

    (1) Average Cryptosporidium occurrence is lower. Median oocyst 
levels for the Information Collection Rule and ICRSS data are 
approximately 0.05/L, which is more than an order of magnitude lower 
than IESWTR estimates.
    (2) Cryptosporidium occurrence is more variable from location to 
location than was shown by the data considered for the IESWTR. This 
indicates that although median occurrence levels are below those 
assumed for the IESWTR, there is a subset of systems whose levels 
are considerably greater than the median.
    (3) There is a smaller difference in Cryptosporidium levels 
between typical filtered and unfiltered system water sources. The 
Information Collection Rule data do not support the IESWTR finding 
that unfiltered water systems have a risk of cryptosporidiosis 
equivalent to that of a filter plant with average quality source 
water.

    This section begins with a summary of occurrence data that were 
used to assess risk under the IESWTR (these data were also used in the 
main risk assessment for the LT1ESWTR). This is followed by a 
discussion of the Information Collection Rule and ICRSS that covers the 
scope of the surveys, analytical methods, results, and a 
characterization of how these new data impact current understanding of 
Cryptosporidium exposure. A more detailed description of occurrence 
data is available in Occurrence and Exposure Assessment for the Long 
Term 2 Enhanced Surface Water Treatment Rule (USEPA 2003b).
1. Occurrence Data Evaluated for IESWTR
    Occurrence information evaluated for the IESWTR is detailed in 
Occurrence and Exposure Assessment for The Interim Enhanced Surface 
Water Treatment Rule (USEPA 1998c). This information is summarized in 
the next two paragraphs.
    a. Filtered systems. In developing the IESWTR, EPA evaluated 
Cryptosporidium occurrence data from a number of studies. Among these 
studies, LeChevallier and Norton (1995) produced the largest data set 
and data from this study were used for the IESWTR risk assessment. This 
study provided estimates of mean occurrence at 69 locations from the 
eastern and central U.S. Although limited by the small number of 
samples per site (one to sixteen samples; most sites were sampled five 
times), variation within and between sites appeared to be lognormal. 
The study's median measured source water concentration was 2.31 
oocysts/L and the interquartile range (i.e., 25th and 75th percentile) 
was 1.03 to 5.15 oocysts/L.
    b. Unfiltered systems. To assess Cryptosporidium occurrence in 
unfiltered systems under the IESWTR, EPA evaluated Cryptosporidium 
monitoring results from several unfiltered water systems that had been 
summarized by the Seattle Water Department (Montgomery Watson, 1995). 
The median (central tendency) of these data was approximately 0.01 
oocysts/L. Thus, the median concentration in these data set was about 2 
orders of magnitude less than the median concentration in the data set 
used for filtered systems. These data, coupled with the assumption that 
filtered systems will remove at least 2 log of Cryptosporidium as 
required by the IESWTR, suggested that unfiltered systems that comply 
with the source water requirements of the SWTR may have a risk of 
cryptosporidiosis equivalent to that of a filter plant using a water 
source of average quality (62 FR 59507, November 3, 1997) (USEPA 
1997a).
2. Overview of the Information Collection Rule and Information 
Collection Rule Supplemental Surveys (ICRSS)
    The Information Collection Rule and the Information Collection Rule 
Supplemental Surveys (ICRSS) were national monitoring studies. They 
were designed to provide EPA with a more comprehensive understanding of 
the occurrence of microbial pathogens in drinking water sources in 
order to support regulatory decision making. The surveys attempted to 
control protozoa measurement error through requiring that (1) 
laboratories meet certain qualification criteria, (2) standardized 
methods be used to collect data, and (3) laboratories analyze 
performance evaluation samples throughout the duration of the study to 
ensure adequate analytical performance. Information Collection Rule 
monitoring took place from July 1997 to December 1998; ICRSS 
Cryptosporidium monitoring

[[Page 47653]]

began in March 1999 and ended in February 2000.
    a. Scope of the Information Collection Rule. The Information 
Collection Rule (61 FR 24354, May 14, 1996) (USEPA 1996a) required 
large PWSs to collect water quality and treatment data related to DBPs 
and microbial pathogens over an 18-month period. PWSs using surface 
water or ground water under the direct influence of surface water as 
sources and serving at least 100,000 people were required to monitor 
their raw water monthly for Cryptosporidium, Giardia, viruses, total 
coliforms, and E. coli. Approximately 350 plants monitored for 
microbial parameters.
    b. Scope of the ICRSS. The ICRSS were designed to complement the 
Information Collection Rule data set with data from systems serving 
fewer than 100,000 people and by employing an improved analytical 
method for protozoa (described later). The ICRSS included 47 large 
systems (serving greater than 100,000 people), 40 medium systems 
(serving 10,000 to 100,000 people) and 39 small systems (serving fewer 
than 10,000 people). Medium and large systems conducted 1 year of 
twice-per-month sampling for Cryptosporidium, Giardia , temperature, 
pH, turbidity, and coliforms. Other water quality measurements were 
taken once a month. Small systems did not test for protozoa but tested 
for all other water quality parameters.
3. Analytical Methods for Protozoa in the Information Collection Rule 
and ICRSS
    This subsection describes analytical methods for Cryptosporidium 
that were used in the Information Collection Rule and ICRSS. 
Information on Cryptosporidium analytical methods is important for the 
LT2ESWTR for several reasons: (1) It is relevant to the quality of 
Cryptosporidium occurrence data used to assess risk and economic impact 
of the LT2ESWTR proposal, (2) it provides a basis for the statistical 
procedures employed to analyze the occurrence data, and (3) it is used 
to assess the adequacy of Cryptosporidium methods to support source-
specific decisions under the LT2ESWTR.
    The Information Collection Rule and ICRSS data sets were generated 
using different analytical methods. The Information Collection Rule 
Protozoan Method (ICR Method) was used to analyze water samples for 
Cryptosporidium during the Information Collection Rule. For the ICRSS, 
a similar but improved method, EPA Method 1622 (later 1623), was used 
for protozoa analyses (samples were analyzed for Cryptosporidium using 
Method 1622 for the first 4 months; then Method 1623 was implemented so 
that Giardia concentrations could also be measured).
    a. Information Collection Rule Protozoan Method. With the 
Information Collection Rule Method (USEPA 1996b), samples were 
collected by passing water through a filter, which was then delivered 
to an EPA-approved Information Collection Rule laboratory for analysis. 
The laboratory eluted the filter, centrifuged the eluate, and separated 
Cryptosporidium oocysts and Giardia cysts from other debris by density-
gradient centrifugation. The oocysts and cysts were then stained and 
counted. Differential interference contrast (DIC) microscopy was used 
to examine internal structures.
    The Information Collection Rule Method provided a quantitative 
measurement of Cryptosporidium oocysts and Giardia cysts, but it is 
believed to have generally undercounted the actual occurrence 
(modeling, described later, adjusted for undercounting). This 
undercounting was due to low volumes analyzed and low method recovery. 
The volume analyzed directly influences the sensitivity of the 
analytical method and the Information Collection Rule Method did not 
require a specific volume analyzed. As a result, sample volumes 
analyzed during the Information Collection Rule varied widely, 
depending on the water matrix and analyst discretion, with a median 
volume analyzed of only 3 L.
    Method recovery characterizes the likelihood that an oocyst present 
in the original sample will be counted. Loss of organisms may occur at 
any step of the analytical process, including filtration, elution, 
concentration of the eluate, and purification of the concentrate. To 
assess the performance of the Information Collection Rule Method, EPA 
implemented the Information Collection Rule Laboratory Spiking Program. 
This program involved collection of duplicate samples on two dates from 
70 plants. On each occasion, one of the duplicate samples was spiked 
with a known quantity of Giardia cysts and Cryptosporidium oocysts (the 
quantity was unknown to the laboratory performing the analysis), and 
both samples were processed according to the method. Recovery of spiked 
Cryptosporidium oocysts ranged from 0% to 65% with a mean of 12% and a 
standard deviation nearly equal to the mean (relative standard 
deviation (RSD) approximately 100%) (Scheller et al. 2002).
    b. Method 1622 and Method 1623. EPA developed Method 1622 (detects 
Cryptosporidium) and 1623 (detects Cryptosporidium and Giardia) to 
achieve higher recovery rates and lower inter- and intra-laboratory 
variability than previous methods. These methods incorporate 
improvements in the concentration, separation, staining, and microscope 
examination procedures. Specific improvements include the use of more 
effective filters, immunomagnetic separation (IMS) to separate the 
oocysts and cysts from extraneous materials present in the water 
sample, and the addition of 4, 6-diamidino-2-phenylindole (DAPI) stain 
for microscopic analysis. The performance of these methods was tested 
through single-laboratory studies and validated through multiple-
laboratory validation (round robin) studies.
    The per-sample volume analyzed for Cryptosporidium during the ICRSS 
was larger than in the Information Collection Rule, due to a 
requirement that laboratories analyze a minimum of 10 L or 2 mL of 
packed pellet with Methods 1622/23 (details in section IV.K). To assess 
method recovery, matrix spike samples were analyzed on five sampling 
events for each plant. The protozoa laboratory spiked the additional 
sample with a known quantity of Cryptosporidium oocysts and Giardia 
cysts (the quantity was unknown to the laboratory performing the 
analysis) and filtered and analyzed both samples using Methods 1622/23. 
Recovery in the ICRSS matrix spike study averaged 43% for 
Cryptosporidium with an RSD of 47% (Connell et al. 2000). Thus, mean 
Cryptosporidium recovery with Methods 1622/23 under the ICRSS was more 
than 3.5 times higher than mean recovery in the Information Collection 
Rule lab spiking program and relative standard deviation was reduced by 
more than half.
    Although Methods 1622 and 1623 have several advantages over the 
Information Collection Rule method, they also have some of the same 
limitations. These methods do not determine whether a cyst or oocyst is 
viable and infectious, and both methods require a skilled microscopist 
and several hours of sample preparation and analyses.
4. Cryptosporidium Occurrence Results from the Information Collection 
Rule and ICRSS
    This section describes Cryptosporidium monitoring results from the 
Information Collection Rule and ICRSS. The focus of this discussion is 
the national distribution of mean Cryptosporidium occurrence levels in 
the sources of filtered and unfiltered plants.

[[Page 47654]]

    The observed (raw, unadjusted) Cryptosporidium data from the 
Information Collection Rule and ICRSS do not accurately characterize 
true concentrations because of (a) the low and variable recovery of the 
analytical method, (b) the small volumes analyzed, and (c) the 
relatively small number of sample events. EPA employed a statistical 
treatment to estimate the true underlying occurrence that led to the 
data observed in the surveys and to place uncertainty bounds about that 
estimation.
    A hierarchical model with Bayesian parameter estimation techniques 
was used to separately analyze filtered and unfiltered system data from 
the Information Collection Rule and the large and medium system data 
from the ICRSS. The model included parameters for location, month, 
source water type, and turbidity. Markov Chain Monte Carlo methods were 
used to estimate these parameters, producing a large number of estimate 
sets that represent uncertainty. This analysis is described more 
completely in Occurrence and Exposure Assessment for the Long Term 2 
Enhanced Surface Water Treatment Rule (USEPA 2003b).
    a. Information Collection Rule results. Figure III-1 presents 
plant-mean Cryptosporidium levels for Information Collection Rule 
plants as a cumulative distribution. Included in Figure III-1 are 
distributions of both the observed raw data adjusted for mean 
analytical method recovery of 12% and the modeled estimate of the 
underlying distribution, along with 90% confidence bounds. The two 
distributions (observed and modeled) are similar for plants where 
Cryptosporidium was detected (196 of 350 Information Collection Rule 
plants did not detect Cryptosporidium in any source water samples). The 
modeled distribution allows for estimation of Cryptosporidium 
concentrations in sources where oocysts may have been present but were 
not detected due to low sample volume and poor method recovery (this 
concept is explained further later in this section).
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    The results shown in Figure III-1 indicate that mean 
Cryptosporidium levels among Information Collection Rule plants vary 
widely, with many plants having relatively little contamination and a 
fraction of plants with elevated source water pathogen levels. The 
median and 90th percentile estimates of Information Collection Rule 
plant-mean Cryptosporidium levels are 0.048 and 1.3 oocysts/L, 
respectively. These levels are lower than Cryptosporidium occurrence 
estimates used in the IESWTR (USEPA 1998c), and the distribution of 
Information

[[Page 47655]]

Collection Rule data is broader (i.e., more source-to-source 
variability). Also, the occurrence of Cryptosporidium in flowing stream 
sources was greater and more variable than in reservoir/lake sources 
(shown in USEPA 2003b).
    The fact that only 44% of Information Collection Rule plants had 
one or more samples positive for Cryptosporidium and that only 7% of 
all Information Collection Rule samples were positive for 
Cryptosporidium suggests that oocyst levels were relatively low in many 
source waters. However, as noted earlier, it is expected that 
Cryptosporidium oocysts were present in many more source waters at the 
time of sampling and were not detected due to poor analytical method 
recovery and low sample volumes.
    This concept is illustrated by Figure III-2, which shows the 
likelihood of no oocysts being detected by the Information Collection 
Rule method as a function of source water concentration (assumes median 
Information Collection Rule sample volume of 3 L). As can be seen in 
Figure III-2, when the source water concentration is 1 oocyst/L, which 
is a relatively high level, the probability of no oocysts being 
detected in a 3 L sample is 73%; for a source water with 0.1 oocyst/L, 
which is close to the median occurrence level, the probability of a 
non-detect is 97%. Consequently, EPA has concluded that it is 
appropriate and necessary to use a statistical model to estimate the 
underlying distribution.
    EPA modeled Cryptosporidium occurrence separately for filtered and 
unfiltered plants that participated in the Information Collection Rule 
because unfiltered plants comply with different regulatory requirements 
than filtered plants. As shown in Table III-3, the occurrence of 
Cryptosporidium was lower for unfiltered sources.
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  Table III-3.--Summary of Information Collection Rule Cryptosporidium
      Modeled Source Water Data for Unfiltered and Filtered Plants
------------------------------------------------------------------------
                                             Information collection rule
                                             modeled plant-mean (oocysts/
                                                          L)
                   Source                   ----------------------------
                                                                 90th
                                              Mean    Median  percentile
------------------------------------------------------------------------
Unfiltered.................................   0.014   0.0079     0.033
Filtered...................................   0.59    0.052      1.4
------------------------------------------------------------------------

    The median Cryptosporidium occurrence level for unfiltered systems 
in the Information Collection Rule was 0.0079 oocysts/L, which is close 
to the median level of 0.01 oocysts/L reported for unfiltered systems 
in the IESWTR (Montgomery Watson, 1995). However, the Information 
Collection Rule data do not show the 2 log difference in median 
Cryptosporidium levels between filtered and unfiltered systems that was 
observed for the data used in the IESWTR. The ratio of median plant-
mean occurrence in unfiltered plants to filtered plants is about 1:7 
(see Table III-3). Thus, based on an assumption of a minimum 2 log 
removal of Cryptosporidium by filtration plants (as required by the 
IESWTR and LT1ESWTR), these data indicate that, on average, finished 
water oocysts levels are higher in unfiltered systems than in filtered 
systems.
    b. ICRSS results. Figures III-3 and III-4 present plant-mean 
Cryptosporidium levels for ICRSS medium and large systems, 
respectively, as cumulative distributions. Medium and large system data 
were analyzed separately to identify differences between the two data 
sets. Similar to the Information Collection Rule data plot, Figures 
III-3 and III-4 include distributions for both the observed raw data 
adjusted for mean analytical method recovery of 43% and the modeled 
estimate of the underlying distribution, along with 90% confidence 
bounds. The observed and modeled distributions are similar for the 85% 
of ICRSS plants that detected Cryptosporidium, and the modeled 
distribution allows for estimation of Cryptosporidium concentrations 
for source waters where oocysts may have been present but were not 
detected.
    Plant-mean Cryptosporidium concentrations for large and medium 
systems in the ICRSS are similar at the mid and lower range of the 
distribution and differ at the upper end. ICRSS medium and large 
systems both had median plant-mean Cryptosporidium levels of 
approximately 0.05 oocysts/L, which is close to the median oocyst level 
in the Information Collection Rule data set as well. However, the 90th 
percentile plant-mean was 0.33 oocysts/L for ICRSS medium systems and 
0.24 oocysts/L for ICRSS large systems. Note that in the Information 
Collection Rule distribution, the 90th percentile Cryptosporidium 
concentration is 1.3 oocysts/L, which is significantly higher than 
either the ICRSS medium or large system distribution.
    The reasons for different results between the surveys are not well 
understood, but may stem from year-to-year variation in occurrence, 
systematic differences in the sampling or measurement methods employed, 
and differences in the populations sampled. This topic is discussed 
further at the end of this section.
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    5. Significance of new Cryptosporidium occurrence data.
    The Information Collection Rule and ICRSS data substantially 
improve overall knowledge of the occurrence distribution of 
Cryptosporidium in drinking water sources. They provide data on many 
more water sources than were available when the IESWTR was developed 
and the data are of more uniform quality. In regard to filtered 
systems, these new data demonstrate two points:

    (1) The occurrence of Cryptosporidium in many drinking water 
sources is lower than was indicated by the data used in IESWTR. 
Median plant-mean levels for the Information Collection Rule and 
ICRSS data sets are approximately 0.05 oocysts/L, whereas the median 
oocyst concentration in the LeChevallier and Norton (1995) data used 
in the IESWTR risk assessment was 2.3 oocysts/L.
    (2) Cryptosporidium occurrence is more variable from plant to 
plant than was indicated by the data considered for the IESWTR 
(i.e., occurrence distribution is broader). This is illustrated by 
considering the ratio of the 90th percentile to the median plant-
mean concentration. In the LeChevallier and Norton (1995) data used 
for the IESWTR, this ratio was 4.6, whereas in the Information 
Collection Rule data, this ratio is 27.

    These data, therefore, support the finding that Cryptosporidium 
levels are relatively low in most water sources, but there is a subset 
of sources with relatively higher concentrations where additional 
treatment may be appropriate.
    In regard to unfiltered plants, the Information Collection Rule 
data are consistent with the Cryptosporidium occurrence estimates for 
unfiltered systems in the IESWTR. However, due to the lower occurrence 
estimates for filtered systems noted previously, the Information 
Collection Rule data do not support the IESWTR finding that unfiltered 
water systems in compliance with the source water requirements of the 
SWTR have a risk of cryptosporidiosis equivalent to that of a well-
operated filter plant using a water source of average quality (63 FR 
69492, December 16, 1998) (USEPA 1998a). Rather, these data indicate 
that Agency conclusions regarding the risk comparison between 
unfiltered and filtered drinking waters must be revised. For protection 
equivalent to that provided by filtered systems, unfiltered systems 
must take additional steps to strengthen their microbial barriers.
6. Request for Comment on Information Collection Rule and ICRSS Data 
Sets
    EPA notes that there are significant differences in the Information 
Collection Rule and ICRSS medium and large system data sets. The median 
values for these data sets are 0.048, 0.050, and 0.045 oocysts/L, 
respectively, while the 90th percentile values are 1.3, 0.33, and 0.24 
oocysts/L. The reasons for these differences are not readily apparent. 
The ICRSS used a newer method with better quality control that yields 
significantly higher recovery, and this suggests that these data are 
more

[[Page 47659]]

reliable for estimating concentrations at individual plants. However, 
the Information Collection Rule included a much larger number of plants 
(350 v. 40 each for the ICRSS medium and large system surveys) and, 
consequently, may be more reliable for estimating occurrence 
nationally. The surveys included a similar number of samples per plant 
(18 v. 24 in the ICRSS). The two surveys cover different time periods 
(7/97-12/98 for the Information Collection Rule and 3/99-2/00 for the 
ICRSS).
    In order to better understand the factors that may account for the 
differences in the three data sets, EPA conducted several additional 
analyses. First, EPA compared results for the subset of 40 plants that 
were in both the Information Collection Rule and ICRSS large system 
surveys. The medians for the two data sets were 0.13 and 0.045 oocysts/
L, respectively, while the 90th percentiles were 1.5 and 0.24 oocysts/
L. Clearly, the discrepancy between the two surveys persists for the 
subsample of data from plants that participated in both surveys. This 
suggests that the different sample groups in the full data sets are not 
the primary factor that accounts for the different results.
    Next, EPA looked at the six month period (July through December) 
that was sampled in two consecutive years (1997 and 1998) during the 
Information Collection Rule survey to investigate year-to-year 
variations at the same plants. Estimated medians for 1997 and 1998 were 
0.062 and 0.040 oocysts/L, respectively, while the 90th percentiles 
were 1.1 and 1.3 oocysts/L. While these comparisons show some interyear 
variability, it is less than the variability observed between the 
Information Collection Rule and ICRSS data sets. EPA has no data 
comparing the same plants using the same methods for the time periods 
in question (1997-98 and 1999-2000) so it is not known if the variation 
between these time periods was larger than the apparent variation 
between 1997 and 1998 in the Information Collection Rule data set.
    The choice of data set has a significant effect on exposure, cost, 
and benefit estimates for the LT2ESWTR. Due to the lack of any clear 
criterion for favoring one data set over the other, EPA has conducted 
the analyses for this proposed rule separately for each, and presents a 
range of estimates based on the three data sets. EPA requests comment 
on this approach. EPA will continue to evaluate the relative strengths 
and limitations of the three data sets, as well as any new data that 
may become available for the final rule.

D. Treatment

1. Overview
    This section presents information on treatment processes for 
reducing the risk from Cryptosporidium in drinking water. Treatment 
information is critical to two aspects of the LT2ESWTR: (1) estimates 
of the efficiency of water filtration plants in removing 
Cryptosporidium are used in assessing risk in treated drinking water 
and (2) the performance and availability of treatment technologies like 
ozone, UV light, and membranes that effectively inactivate or remove 
Cryptosporidium impact the feasibility of requiring additional 
treatment for this pathogen.
    The majority of plants treating surface water use conventional 
filtration treatment, which is defined in 40 CFR 141.2 as a series of 
processes including coagulation, flocculation, sedimentation, and 
filtration. Direct filtration, which is typically used on sources with 
low particulate levels, includes coagulation and filtration but not 
sedimentation. Other common filtration processes are slow sand, 
diatomaceous earth (DE), membranes, and bag and cartridge filters.
    For the IESWTR (and later the LT1ESWTR), EPA evaluated results from 
pilot and full scale studies of Cryptosporidium removal by various 
types of filtration plants. Based on these studies, EPA concluded that 
conventional and direct filtration plants meeting IESWTR filter 
effluent turbidity standards will achieve a minimum 2 log (99%) removal 
of Cryptosporidium. The Agency reached the same conclusion for slow 
sand and DE filtration plants meeting SWTR turbidity standards. 
Treatment credit for technologies like membranes and bag and cartridge 
filters was to be made on a product-specific basis.
    Subsequent to promulgating the IESWTR and LT1ESWTR, EPA has 
reviewed additional studies of the performance of treatment plants in 
removing Cryptosporidium, as well as other micron size particles (e.g., 
aerobic spores) that may serve as indicators of Cryptosporidium 
removal. As discussed later in this section, the Agency has concluded 
that these studies support an estimate of 3 log (99.9%) for the average 
Cryptosporidium removal efficiency of conventional treatment plants in 
compliance with the IESWTR or LT1ESWTR. Section IV.A describes how this 
estimate of average removal efficiency is used in determining the need 
for additional Cryptosporidium treatment under the LT2ESWTR. Further, 
this estimate is consistent with the Stage 2 M-DBP Agreement in 
Principle, which states as follows:

    The additional treatment requirements in the (LT2ESWTR) bin 
requirement table are based, in part, on the assumption that 
conventional treatment plants in compliance with the IESWTR achieve 
an average of 3 logs removal of Cryptosporidium.

    In addition, the Agency finds that available data support an 
estimate of 3 log average Cryptosporidium removal for well operated 
slow sand and DE plants. Direct filtration plants are estimated to 
achieve a 2.5 log average Cryptosporidium reduction, in consideration 
of the absence of a sedimentation process in these plants.
    The most significant developments in the treatment of 
Cryptosporidium since IESWTR promulgation are in the area of 
inactivation. During IESWTR development, EPA determined that available 
data were not sufficient to identify criteria for awarding 
Cryptosporidium treatment credit for any disinfectant. As presented in 
section IV.C.14, EPA has now acquired the necessary data to specify the 
disinfectant concentrations and contact times necessary to achieve 
different levels of Cryptosporidium inactivation with chlorine dioxide 
and ozone. Additionally, recent studies have demonstrated that UV light 
will produce high levels of Cryptosporidium and Giardia lamblia 
inactivation at low doses. Section IV.C.15 provides criteria for 
systems to achieve credit for disinfection of Cryptosporidium, Giardia 
lamblia, and viruses by UV.
    This section begins with a summary of treatment information 
considered for the IESWTR and LT1ESWTR, followed by a discussion of 
additional data that EPA has evaluated since promulgating those 
regulations. Further information on treatment of Cryptosporidium is 
available in Technologies and Costs for Control of Microbial 
Contaminants and Disinfection Byproducts (USEPA 2003c), Occurrence and 
Exposure Assessment for the Long Term 2 Enhanced Surface Water 
Treatment Rule (USEPA 2003b) and section IV.C of this preamble.
2. Treatment information considered for the IESWTR and LT1ESWTR
    Treatment studies that were evaluated during development of the 
IESWTR are described in the IESWTR NODA (62 FR 59486, November 3, 1997) 
(USEPA 1997b), the Regulatory Impact Analysis for the IESWTR (USEPA 
1998d), and Technologies and Costs for the Microbial Recommendations of 
the M/DBP Advisory Committee (USEPA 1997b). Treatment information 
considered in development of the

[[Page 47660]]

LT1ESWTR is described in the proposed rule (65 FR 59486, April 10, 
2000) (USEPA 2000b). Pertinent information is summarized in the 
following paragraphs.
    a. Physical removal. EPA evaluated eight studies on removal of 
Cryptosporidium by rapid granular filtration for the IESWTR. These were 
Patania et al. (1995), Nieminski and Ongerth (1995), Ongerth and 
Pecoraro (1995), LeChevallier and Norton (1992), LeChevallier et al. 
(1991), Foundation for Water Research (1994), Kelley et al. (1995), and 
West et al. (1994). These studies included both pilot and full scale 
plants.
    Full scale plants in these studies typically demonstrated 2-3 log 
removal of Cryptosporidium, and pilot plants achieved up to almost 6 
log removal under optimized conditions. In general, the degree of 
removal that can be quantified in full scale plants is limited because 
Cryptosporidium levels following filtration are often below the 
detection limit of the analytical method. Pilot scale studies overcome 
this limitation by seeding high concentrations of oocysts to the plant 
influent, but extrapolation of the performance of a pilot plant to the 
routine performance of full scale plants is uncertain.
    Cryptosporidium removal efficiency in these studies was observed to 
depend on a number of factors including: water matrix, coagulant 
application, treatment optimization, filtered water turbidity, and the 
filtration cycle. The highest removal rates were observed in plants 
that achieved very low effluent turbidities.
    EPA also evaluated studies of Cryptosporidium removal by slow sand 
(Schuler and Ghosh 1991, Timms et al. 1995) and DE filtration (Schuler 
and Gosh 1990) for the IESWTR. These studies indicated that a well 
designed and operated plant using these processes could achieve 3 log 
or greater removal of Cryptosporidium.
    After considering these studies, EPA concluded that conventional 
and direct filtration plants in compliance with the effluent turbidity 
criteria of the IESWTR, and slow sand and DE plants in compliance with 
the effluent turbidity criteria established for these processes by the 
SWTR, would achieve at least 2 log removal of Cryptosporidium. 
Recognizing that many plants will achieve more than the minimum 2 log 
reduction, EPA estimated median Cryptosporidium removal among 
filtration plants as near 3 log (99.9%) for the purpose of assessing 
risk.
    The LT1ESWTR proposal included summaries of additional studies of 
Cryptosporidium removal by conventional treatment (Dugan et al. 1999), 
direct filtration (Swertfeger et al. 1998), and DE filtration (Ongerth 
and Hutton 1997). These studies supported IESWTR conclusions stated 
previously regarding the performance of these processes. The LT1ESWTR 
proposal also summarized studies of membranes, bag filters, and 
cartridge filters (Jacangelo et al. 1995, Drozd and Schartzbrod 1997, 
Hirata and Hashimoto 1998, Goodrich et al. 1995, Collins et al. 1996, 
Lykins et al. 1994, Adham et al. 1998). This research demonstrated that 
these technologies may be capable of achieving 2 log or greater removal 
of Cryptosporidium. However, EPA concluded that variation in 
performance among different manufacturers and models necessitates that 
determinations of treatment credit be made on a technology-specific 
basis (65 FR 19065, April 10, 2000) (USEPA 2000b).
    b. Inactivation. In the IESWTR NODA (62 FR 59486) (USEPA 1997a), 
EPA cited studies that demonstrated that chlorine is ineffective for 
inactivation of Cryptosporidium at doses practical for treatment plants 
(Korich et al. 1990, Ransome et al. 1993, Finch et al. 1997). The 
Agency also summarized studies of Cryptosporidium inactivation by UV, 
ozone, and chlorine dioxide. EPA evaluated these disinfectants to 
determine if sufficient data were available to develop prescriptive 
disinfection criteria for Cryptosporidium.
    The studies of UV disinfection of Cryptosporidium that were 
available during IESWTR development were inconclusive due to 
methodological factors. These studies included: Lorenzo-Lorenzo et al. 
(1993), Ransome et al. (1993), Campbell et al. (1995), Finch et al. 
(1997), and Clancy et al. (1997). A common limitation among these 
studies was the use of in vitro assays, such as excystation and vital 
dye staining, to measure loss of infectivity. These assays subsequently 
were shown to overestimate the UV dose needed to inactivate protozoa 
(Clancy et al. 1998, Craik et al. 2000). In another case, a reactor 
vessel that blocked germicidal light was used (Finch et al. 1997).
    EPA evaluated the following studies of ozone inactivation of 
Cryptosporidium for the IESWTR: Peeters et al. (1989), Korich et al. 
(1990), Parker et al. (1993), Ransome et al. (1993), Finch et al. 
(1997), Daniel et al. (1993), and Miltner et al. (1997). These studies 
demonstrated that ozone could achieve high levels of Cryptosporidium 
inactivation, albeit at doses much higher than those required to 
inactivate Giardia. Results of these studies also exhibited significant 
variability due to factors like different infectivity assays and 
methods of dose calculation.
    The status of chlorine dioxide inactivation of Cryptosporidium 
during IESWTR development was similar to that of ozone. EPA evaluated a 
number of studies that indicated that relatively high doses of chlorine 
dioxide could achieve significant inactivation of Cryptosporidium 
(Peeters et al. 1989, Korich et al. 1990, Ransome et al. 1993, Finch et 
al. 1995 and 1997, and LeChevallier et al. 1997). Data from these 
studies showed a high level of variability due to methodological 
differences, and the feasibility of high chlorine dioxide doses was 
uncertain due to the MCL for chlorite that was established by the Stage 
1 DBPR.
    After reviewing these studies, EPA and the Stage 1 Federal Advisory 
Committee concluded that available data were not adequate to award 
Cryptosporidium inactivation credit for UV, ozone, or chlorine dioxide.
3. New Information on Treatment for Control of Cryptosporidium
    a. Conventional filtration treatment and direct filtration. This 
section provides brief descriptions of seven recent studies of 
Cryptosporidium removal by conventional treatment and direct 
filtration, followed by a summary of key points.
    Dugan et al. (2001) evaluated the ability of conventional treatment 
to control Cryptosporidium under varying water quality and treatment 
conditions, and assessed turbidity, total particle counts (TPC), and 
aerobic endospores as indicators of Cryptosporidium removal. Fourteen 
runs were conducted on a small pilot scale plant that had been 
determined to provide equivalent performance to a larger plant. Under 
optimal coagulation conditions, oocyst removal across the sedimentation 
basin ranged from 0.6 to 1.8 log, averaging 1.3 log, and removal across 
the filters ranged from 2.9 to greater than 4.4 log, averaging greater 
than 3.7 log. Removal of aerobic spores, TPC, and turbidity all 
correlated with removal of Cryptosporidium by sedimentation, and these 
parameters were conservative indicators of Cryptosporidium removal 
across filtration. Sedimentation removal under optimal conditions 
related to raw water quality, with the lowest Cryptosporidium removals 
observed when raw water turbidity was low.
    Suboptimal coagulation conditions (underdosed relative to jar test 
predictions) significantly reduced plant

[[Page 47661]]

performance. Oocyst removal in the sedimentation basin averaged 0.2 
log, and removal by filtration averaged 1.5 log. Under suboptimal 
coagulation conditions, low sedimentation removals of Cryptosporidium 
were observed regardless of raw water turbidity.
    Nieminski and Bellamy (2000) investigated surrogates as indicators 
of Giardia and Cryptosporidium in source water and as measures of 
treatment plant effectiveness. It involved sampling for microbial 
pathogens (Giardia, Cryptosporidium, and enteric viruses), potential 
surrogates (bacteria, bacteria spores, bacterial phages, turbidity, 
particles), and other water quality parameters in the source and 
finished waters of 23 surface water filtration facilities and one 
unfiltered system.
    While Giardia and Cryptosporidium were found in the majority of 
source water samples, the investigators could not establish a 
correlation between either occurrence or removal of these protozoa and 
any of the surrogates tested. This was attributed, in part, to low 
concentrations of Giardia and Cryptosporidium in raw water and high 
analytical method detection limits. Removal of Cryptosporidium and 
Giardia averaged 2.2 and 2.6 log, respectively, when conservatively 
estimated using detection limits in filtered water. Aerobic spores were 
found in 85% of filtered water samples and were considered a measure of 
general treatment effectiveness. Average reduction of aerobic spores 
was 2.84 log. Direct filtration plants removed fewer aerobic spores 
than conventional or softening plants.
    McTigue et al. (1998) conducted an on-site survey of 100 treatment 
plants for particle counts, pathogens (Cryptosporidium and Giardia), 
and operational information. The authors also performed pilot scale 
spiking studies. Median removal of particles greater than 2 mm was 2.8 
log, with values ranging from 0.04 to 5.5 log. Removal generally 
increased with increasing raw water particle concentration. Results 
were consistent with previously collected data. Cryptosporidium and 
Giardia were found in the majority of raw water sources, but 
calculation of their log removal was limited by the concentration 
present. River sources had a higher incidence of pathogen occurrence. 
Direct filtration plants had higher levels of pathogens in the filtered 
water than others in the survey.
    Nearly all of the filter runs evaluated in the survey exhibited 
spikes where filtered water particle counts increased, and pilot work 
showed that pathogens are more likely to be released during these spike 
events. Cryptosporidium removal in the pilot scale spiking study 
averaged nearly 4 log, regardless of the influent oocyst concentration. 
Pilot study results indicated a strong relationship between removal of 
Cryptosporidium and removal of particles ( 3 [mu]m) during 
runs using optimal coagulation and similar temperatures.
    Patania et al. (1999) evaluated removal of Cryptosporidium at 
varied raw water and filter effluent turbidity levels using direct 
filtration. Runs were conducted with both low (2 NTU) and high (10 NTU) 
raw water turbidity. Targeted filtered water turbidity was either 0.02 
or 0.05 NTU. At equivalent filtered water turbidity, Cryptosporidium 
removal was slightly higher when the raw water turbidity was higher. 
Also, Cryptosporidium removal was enhanced by an average of 1.5 log 
when steady-state filtered water turbidity was 0.02 NTU compared to 
0.05 NTU.
    Huck et al. (2000) evaluated filtration efficiency during optimal 
and suboptimal coagulation conditions with two pilot scale filtration 
plants. One plant employed a high coagulation dose for both total 
organic carbon (TOC) and particle removal, and the second plant used a 
low dose intended for particle removal only. Under optimal operating 
conditions, which were selected to achieve filtered water turbidity 
below 0.1 NTU, median Cryptosporidium removal was 5.6 log at the high 
coagulant dose plant and 3 log at the low dose plant. Under suboptimal 
coagulation conditions, where the coagulant dose was reduced to achieve 
filtered water turbidity of 0.2 to 0.3 NTU, median Cryptosporidium 
removals dropped to 3.2 log and 1 log at the high dose and low dose 
plants, respectively. Oocyst removal also decreased substantially at 
the end of the filter cycle, although this was not always indicated by 
an increase in turbidity. Runs conducted with no coagulant resulted in 
very little Cryptosporidium removal.
    Emelko et al. (2000) investigated Cryptosporidium removal during 
vulnerable filtration periods using a pilot scale direct filtration 
system. The authors evaluated four different operational conditions: 
stable, early breakthrough, late breakthrough, and end of run. During 
stable operation, effluent turbidity was approximately 0.04 NTU and 
Cryptosporidium removal ranged from 4.7 to 5.8 log. In the early 
breakthrough period, effluent turbidity increased from approximately 
0.04 to 0.2 NTU, and Cryptosporidium removal decreased significantly, 
averaging 2.1 log. For the late breakthrough period, where effluent 
turbidity began at approximately 0.25 NTU and ended at 0.35 NTU, 
Cryptosporidium removal dropped to an average of 1.4 log. Two 
experiments tested Cryptosporidium removal during the end-of-run 
operation, when effluent turbidities generally start increasing. 
Turbidity started at about 0.04 NTU for both experiments and ended at 
0.06 NTU for the first experiment and 0.13 NTU for the second. Reported 
Cryptosporidium removal ranged from 1.8 to 3.3 log, with an average of 
2.5 log for both experiments.
    Harrington et al. (2001) studied the removal of Cryptosporidium and 
emerging pathogens by filtration, sedimentation, and dissolved air 
flotation (DAF) using bench scale jar tests and pilot scale 
conventional treatment trains. In the bench scale experiments, all run 
at optimized coagulant doses, mean log removal of Cryptosporidium was 
1.2 by sedimentation and 1.7 by DAF. Cryptosporidium removal was 
similar in all four water sources that were evaluated and was not 
significantly affected by lower pH or coagulant aid addition. However, 
removal of Cryptosporidium was greater at 22[deg]C than at 5[deg]C, and 
was observed to be higher with alum coagulant than with either 
polyaluminum hydroxychlorosulfate or ferric chloride.
    In the pilot scale experiments, mean log removal of Cryptosporidium 
was 1.9 in filtered water with turbidity of 0.2 NTU or less. Removal 
increased as filtered water turbidity dropped below 0.3 NTU. There was 
no apparent effect of filtration rate on removal efficiency. In 
comparing Cryptosporidium removal by sand, dual media (anthracite/
sand), and trimedia (anthracite/sand/garnet) filters, no difference was 
observed near neutral pH. However, at pH 5.7, removal increased 
significantly in the sand filter and it outperformed the other filter 
media configurations. The authors found no apparent explanation for 
this behavior. There was no observable effect of a turbidity spike on 
Cryptosporidium removal.
Significance of Conventional and Direct Filtration Studies
    The performance of treatment plants under current regulations is a 
significant factor in determining the need for additional treatment. As 
described in section IV.A, the proposed Cryptosporidium treatment 
requirements associated with LT2ESWTR risk bins for filtered systems 
are based, in part, on an estimate that conventional plants in 
compliance with

[[Page 47662]]

the IESWTR achieve an average of 3 log Cryptosporidium removal. The 
following discussion illustrates why EPA believes that available data 
support this estimate.
    While Cryptosporidium removal at full scale plants is difficult to 
quantify due to limitations with analytical methods, pilot scale 
studies show that reductions in aerobic spores and total particle 
counts are often conservative indicators of filtration plant removal 
efficiency for Cryptosporidium (Dugan et al. 2001, McTigue et al. 1998, 
Yates et al. 1998, Emelko et al. 1999 and 2000). Surveys of full scale 
plants have reported average reductions near 3 log for both aerobic 
spores (Nieminski and Bellamy, 2000) and total particle counts (McTigue 
et al. 1998). Consequently, these findings are consistent with an 
estimate that average removal of Cryptosporidium by filtration plants 
is approximately 3 log.
    Pilot scale Cryptosporidium spiking studies (Dugan et al. 2001, 
Huck et al. 2000, Emelko et al. 2000, McTigue et al. 1998, Patania et 
al. 1995) suggest that a conventional treatment plant has the potential 
to achieve greater than 5 log removal of Cryptosporidium under optimal 
conditions. However, these high removals are typically observed at very 
low filter effluent turbidity values, and the data show that removal 
efficiency can decrease substantially over the course of a filtration 
cycle or if coagulation is not optimized (Dugan et al. 2001, Huck et 
al. 2000, Emelko et al. 2000, Harrington et al. 2001). Removal 
efficiency also appears to be impacted by source water quality (Dugan 
et al. 2001, McTigue et al. 1998). Given these considerations, EPA 
believes that 3 log is a reasonable estimate of average Cryptosporidium 
removal efficiency for conventional treatment plants in compliance with 
the IESWTR or LT1ESWTR.
    The Stage 2 M-DBP Advisory Committee did not address direct 
filtration plants, which lack the sedimentation basin of a conventional 
treatment train, but recommended that EPA address these plants in the 
LT2ESWTR proposal (65 FR 83015, December 29, 2000) (USEPA 2000a). While 
some studies have observed similar levels of Cryptosporidium removal in 
direct and conventional filtration plants (Nieminski and Ongerth, 1995, 
Ongerth and Pecoraro 1995), EPA has concluded that the majority of 
available data support a lower estimate of Cryptosporidium removal 
efficiency for direct filtration plants.
    As described in section IV.C.5, pilot and full scale studies 
demonstrate that sedimentation basins, which are absent in direct 
filtration, can achieve 0.5 log or greater Cryptosporidium reduction 
(Dugan et al. 2001, Patania et al. 1995, Edzwald and Kelly 1998, 
Payment and Franco 1993, Kelley et al. 1995). In addition, Patania et 
al. (1995) observed direct filtration to achieve less Cryptosporidium 
removal than conventional treatment, and McTigue et al. (1998) found a 
higher incidence of Cryptosporidium in the treated water of direct 
filtration plants. Given these findings, EPA has estimated that direct 
filtration plants achieve an average of 2.5 log Cryptosporidium 
reduction (i.e., 0.5 log less than conventional treatment).
    i. Dissolved air flotation. Dissolved air flotation (DAF) is a 
solid-liquid separation process that can be used in conventional 
treatment trains in place of gravity sedimentation. DAF takes advantage 
of the buoyancy of oocysts by floating oocyst/particle complexes to the 
surface for removal. In DAF, air is dissolved in pressurized water, 
which is then released into a flotation tank containing flocculated 
particles. As the water enters the tank, the dissolved air forms small 
bubbles that collide with and attach to floc particles and float to the 
surface (Gregory and Zabel, 1990).
    In comparing DAF with gravity sedimentation, Plummer et al. (1995) 
observed up to 0.81 log removal of oocysts in the gravity sedimentation 
process, while DAF achieved 0.38 to 3.7 log removal, depending on 
coagulant dose. Edzwald and Kelley (1998) demonstrated a 3 log removal 
of oocysts using DAF, compared with a 1 log removal using gravity 
sedimentation in the clarification process before filtration. In bench 
scale testing by Harrington et al. (2001), DAF averaged 0.5 log higher 
removal of Cryptosporidium than gravity sedimentation. Based on these 
results, EPA has concluded that a treatment plant using DAF plus 
filtration can achieve levels of Cryptosporidium removal equivalent to 
or greater than a conventional treatment plant with gravity 
sedimentation.
    b. Slow sand filtration. Slow sand filtration is a process 
involving passage of raw water through a bed of sand at low velocity 
(generally less than 0.4 m/h) resulting in substantial particulate 
removal by physical and biological mechanisms. For the LT2ESWTR 
proposal, EPA has reviewed two additional studies of slow sand 
filtration.
    Fogel et al. (1993) evaluated removal efficiencies for 
Cryptosporidium and Giardia with a full scale slow sand filtration 
plant. The removals ranged from 0.1-0.5 log for Cryptosporidium and 
0.9-1.4 log for Giardia. Raw water turbidity ranged from 1.3 to 1.6 NTU 
and decreased to 0.35-0.31 NTU after filtration. The authors attributed 
the low Cryptosporidium and Giardia removals to the relatively poor 
grade of filter media and lower water temperature. The sand had a 
higher uniformity coefficient than recommended by design standards. 
This creates larger pore spaces within the filter bed that retard 
biological removal capacity. Lower water temperatures (1 [deg]C) also 
decreased biological activity in the filter media.
    Hall et al. (1994) examined the removal of Cryptosporidium with a 
pilot scale slow sand filtration plant. Cryptosporidium removals ranged 
from 2.8 to 4.3 log after filter maturation, with an average of 3.8 log 
(at least one week after filter scraping). Raw water turbidity ranged 
from 3.0 NTU to 7.5 NTU for three of four runs and 15.0 NTU for a 
fourth run. Filtered water turbidity was 0.2 to 0.4 NTU, except for the 
fourth run which had 2.5 NTU filtered water turbidity. This study also 
included an investigation of Cryptosporidium removal during filter 
start-up where the filtration rate was slowly increased over a 4 day 
period. Results indicate that filter ripening did not appear to affect 
Cryptosporidium removal.
    The study by Fogel et al. is significant because it indicates that 
a slow sand filtration plant may achieve less than 2 log removal of 
Cryptosporidium removal while being in compliance with the effluent 
turbidity requirements of the IESWTR and LT1ESWTR. The authors 
attributed this poor performance to the filter being improperly 
designed, which, if correct, illustrates the importance of proper 
design for removal efficiency in slow sand filters. In contrast, the 
study by Hall et al. (1994) supports other work (Schuler and Ghosh 
1991, Timms et al. 1995) in finding that slow sand filtration can 
achieve Cryptosporidium removal greater than 3 log. Overall, this body 
of work appears to show that slow sand filtration has the potential to 
achieve Cryptosporidium removal efficiencies similar to that of a 
conventional plant, but proper design and operation are critical to 
realizing treatment goals.
    c. Diatomaceous earth filtration. Diatomaceous earth filtration is 
a process in which a precoat cake of filter media is deposited on a 
support membrane and additional filter media is continuously added to 
the feed water to maintain the permeability of the filter cake. Since 
the IESWTR and LT1ESWTR, EPA has reviewed one new study of DE 
filtration (Ongerth and Hutton 2001). It supports the findings of

[[Page 47663]]

earlier studies (Schuler and Gosh 1990, Ongerth and Hutton 1997) in 
showing that a well designed and operated DE plant can achieve 
Cryptosporidium removal equivalent to a conventional treatment plant 
(i.e., average of 3 log).
    d. Other filtration technologies. In today's proposal, information 
about bag filters, cartridge filters, and membranes, including criteria 
for awarding Cryptosporidium treatment credit, is presented in section 
IV.C as part of the microbial toolbox. Section IV.C also addresses 
credit for pretreatment options like presedimentation basins and bank 
filtration.
    e. Inactivation. Substantial advances in understanding of 
Cryptosporidium inactivation by ozone, chlorine dioxide, and UV have 
been made following the IESWTR and LT1ESWTR. These advances have 
allowed EPA to develop criteria to award Cryptosporidium treatment 
credit for these disinfectants. Relevant information is summarized 
next, with additional information sources noted.
    i. Ozone and chlorine dioxide. With the completion of several major 
studies, EPA has acquired sufficient information to develop standards 
for the inactivation of Cryptosporidium by ozone and chlorine dioxide. 
For both of these disinfectants, today's proposal includes CT tables 
that specify a level of Cryptosporidium treatment credit based on the 
product of disinfectant concentration and contact time.
    For ozone, the CT tables in today's proposal were developed through 
considering four sets of experimental data: Li et al. (2001), Owens et 
al. (2000), Oppenheimer et al. (2000), and Rennecker et al. (1999). 
Chlorine dioxide CT tables are based on three experimental data sets: 
Li et al. (2001), Owens et al. (1999), and Ruffell et al. (2000). 
Together these studies provide a large body of data that covers a range 
of water matrices, both laboratory and natural. While the data exhibit 
variability, EPA believes that collectively they are sufficient to 
determine appropriate levels of treatment credit as a function of 
disinfection conditions. CT tables for ozone and chlorine dioxide 
inactivation of Cryptosporidium are presented in Section IV.C.14 of 
this preamble.
    ii. Ultraviolet light. A major recent development is the finding 
that UV light is highly effective for inactivating Cryptosporidium and 
Giardia at low doses. Research prior to 1998 had indicated that very 
high doses of UV light were required to achieve substantial 
disinfection of protozoa. However, as noted previously, these results 
were largely based on the use of in vitro assays, which were later 
shown to substantially overestimate the UV doses required to prevent 
infection (Clancy et al. 1998, Bukhari et al. 1999, Craik et al. 2000). 
Recent research using in vivo assays (e.g., neonatal mouse infectivity) 
and cell culture techniques to measure infectivity has provided strong 
evidence that both Cryptosporidium and Giardia are highly sensitive to 
low doses of UV.

BILLING CODE 6560-50-P

[[Page 47664]]

[GRAPHIC] [TIFF OMITTED] TP11AU03.004

BILLING CODE 6560-50-C
    Figure III-5 presents data from selected studies of UV inactivation 
of Cryptosporidium. While the data in Figure III-5 show substantial 
scatter, they are consistent in demonstrating a high level of 
inactivation at relatively low UV doses. These studies generally 
demonstrated at least 3 log Cryptosporidium inactivation at UV doses of 
10 mJ/cm 2 and higher. In comparison, typical UV dose for 
drinking water disinfection are 30 to 40 mJ/cm 2. A recent 
investigation by Clancy et al. (2002) showed that UV light at 10 mJ/cm 
2 provided at least 4 log inactivation of five strains of 
Cryptosporidium that are infectious to humans. Studies of UV 
inactivation of Giardia have reported similar results (Craik et al. 
2000, Mofidi et al. 2002, Linden et al. 2002, Campbell and Wallis 2002, 
Hayes et al. 2003).
    In addition to efficacy for protozoa inactivation, data indicate 
that UV disinfection does not promote the formation of DBPs (Malley et 
al. 1995, Zheng et al. 1999). Malley et al. (1995) evaluated DBP 
formation in a number of surface and ground waters with UV doses 
between 60 and 200 mJ/cm\2\. UV light did not directly form DBPs, such 
as trihalomethanes (THM) and haloacetic acids (HAA), and did not alter 
the concentration or species of DBPs formed by post-disinfection with 
chlorine or chloramines. A study by Zheng et al. (1999) reported that 
applying UV light following chlorine disinfection had little impact on 
THM and HAA formation. In addition, data suggest that photolysis of 
nitrate to nitrite, a potential concern with certain types of UV lamps, 
will not result in nitrite levels near the MCL under typical drinking 
water conditions (Peldszus et al. 2000, Sharpless and Linden 2001).
    These studies demonstrate that UV light is an effective technology 
for inactivating Giardia and Cryptosporidium, and that it does not form 
DBPs at levels of concern in drinking water. Section IV.C.15 describes 
proposed criteria for awarding treatment credit for UV inactivation of 
Cryptosporidium, Giardia lamblia, and viruses. These criteria include 
UV dose tables, validation testing, and monitoring standards. In 
addition, EPA is preparing a UV Disinfection Guidance Manual with 
information on design, testing, and operation of UV systems. A draft of 
this guidance is available in the docket for today's proposal (http://www.epa.gov/edocket/).
    iii. Significance of new information on inactivation. The research 
on ozone, chlorine dioxide, and UV light described in this proposal has 
made these disinfectants available for systems to use in meeting 
additional Cryptosporidium treatment requirements under LT2ESWTR. This 
overcomes a significant limitation to establishing inactivation 
requirements for Cryptosporidium that existed when the IESWTR was 
developed. The Stage 1 Advisory Committee recognized the need for 
inactivation criteria if EPA were to consider a risk based proposal

[[Page 47665]]

for Cryptosporidium in future rulemaking (62 FR 59498, November 3, 
1997) (USEPA 2000b). The CT tables for ozone and chlorine dioxide 
provide such criteria. In addition, the availability of UV furnishes 
another relatively low cost tool to achieve Cryptosporidium 
inactivation and DBP control.
    While no single treatment technology is appropriate for all 
systems, EPA believes that these disinfectants, along with the other 
management and treatment options in the microbial toolbox presented in 
section IV.C, make it feasible for systems to meet the additional 
Cryptosporidium treatment requirements in today's proposal.

IV. Discussion of Proposed LT2ESWTR Requirements

A. Additional Cryptosporidium Treatment Technique Requirements for 
Filtered Systems

1. What Is EPA Proposing Today?
    a. Overview of framework approach. EPA is proposing treatment 
technique requirements to supplement the existing requirements of the 
SWTR, IESWTR, and LT1ESWTR (see section II.B). The proposed 
requirements will achieve increased protection against Cryptosporidium 
in public water systems that use surface water or ground water under 
the direct influence of surface water as sources. Under this proposal, 
filtered systems will be assigned to one of four risk categories (or 
``bins''), based on the results of source water Cryptosporidium 
monitoring. Systems assigned to the lowest risk bin incur no additional 
treatment requirements, while systems assigned to higher risk bins must 
reduce Cryptosporidium levels beyond IESWTR and LT1ESWTR requirements. 
Systems will comply with additional Cryptosporidium treatment 
requirements by selecting treatment and management strategies from a 
``microbial toolbox'' of control options.
    Today's proposal reflects recommendations from the Stage 2 M-DBP 
Federal Advisory Committee (65 FR 83015, December 29, 2000) (USEPA 
2000a), which described this approach as a ``microbial framework''. 
This approach targets additional treatment requirements to those 
systems with the highest source water Cryptosporidium levels and, 
consequently, the highest vulnerability to this pathogen. In so doing, 
today's proposal builds upon the current treatment technique 
requirement for Cryptosporidium under which all filtered systems must 
achieve at least a 2 log reduction, regardless of source water quality. 
The intent of this proposal is to assure that public water systems with 
the higher risk source water achieve a level of public health 
protection commensurate with systems with less contaminated source 
water.
    b. Monitoring requirements. Today's proposal requires systems to 
monitor their source water (influent water prior to treatment plant) 
for Cryptosporidium, E. coli, and turbidity. The purpose of the 
monitoring is to assess source water Cryptosporidium levels and, 
thereby, classify systems in different risk bins. Proposed monitoring 
requirements for large and small systems are summarized in Table IV-I 
and are characterized in the following discussion.
Large Systems
    Large systems (serving at least 10,000 people) must sample their 
source water at least monthly for Cryptosporidium, E. coli, and 
turbidity for a period of 2 years, beginning no later than 6 months 
after LT2ESWTR promulgation. Systems may sample more frequently (e.g., 
twice-per-month, once-per-week), provided the same sampling frequency 
is used throughout the 2-year monitoring period. As described in 
section IV.A.1.c, systems that sample more frequently (at least twice-
per-month) use a different calculation that is potentially less 
conservative to determine their bin classification.
    The purpose of requiring large systems to collect E. coli and 
turbidity data is to further evaluate these parameters as indicators to 
identify drinking water sources that are susceptible to high 
concentrations of Cryptosporidium. As described next, these data will 
be applied to small system LT2ESWTR monitoring.
Small Systems
    EPA is proposing a 2-phase monitoring strategy for small systems 
(serving fewer than 10,000 people) to reduce their monitoring burden. 
This approach is based on Information Collection Rule and ICRSS data 
indicating that systems with low source water E. coli levels are likely 
to have low Cryptosporidium levels, such that additional treatment 
would not be required under the LT2ESWTR. Under this approach, small 
systems must initially conduct one year of bi-weekly sampling (one 
sample every two weeks) for E. coli, beginning 2.5 years after LT2ESWTR 
promulgation. Small systems are triggered into Cryptosporidium 
monitoring only if the initial E. coli monitoring indicates a mean 
concentration greater than 10 E. coli/100 mL for systems using a 
reservoir or lake as their primary source or greater than 50 E. coli/
100 mL for systems using a flowing stream as their primary source. 
Small systems that exceed these E. coli trigger values must conduct one 
year of twice-per-month Cryptosporidium sampling, beginning 4 years 
after LT2ESWTR promulgation.
    The analysis supporting the proposed E. coli values that trigger 
Cryptosporidium monitoring by small systems is presented in Section 
IV.A.2. However, as recommended by the Stage 2 M-DBP Advisory 
Committee, EPA will evaluate Cryptosporidium indicator relationships in 
the LT2ESWTR monitoring data collected by large systems. If these data 
support the use of different indicator levels to trigger small system 
Cryptosporidium monitoring, EPA will issue guidance with 
recommendations. The proposed LT2ESWTR allows States to specify 
alternative indicator values for small systems, based on EPA guidance.

                                                      Table IV-1.--LT2ESWTR Monitoring Requirements
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           Monitoring parameters and sample frequency requirements
        Public water systems            Monitoring begins     Monitoring duration  ---------------------------------------------------------------------
                                                                                        Cryptosporidium            E. coli               Turbidity
--------------------------------------------------------------------------------------------------------------------------------------------------------
Large systems (serving 10,000 or     6 months after          2 years..............  minimum 1 sample/month  minimum 1 sample/      minimum 1 measurement/
 more people).                        promulgation of                                b.                      month b.               month b.
                                      LT2ESWTR a.
Small systems (serving fewer than    30 months (2\1/2\       1 year...............  See following rows....  1 sample every two     N/A
 10,000 people).                      years) after                                                           weeks.
                                      promulgation of
                                      LT2ESWTR.
------------------------------------

[[Page 47666]]

 
              Possible additional monitoring requirement for Cryptosporidium. If small systems exceed E. coli trigger levels c, then * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Small systems (serving fewer than    48 months (4 years)     1 year...............  2 samples/month.......  N/A..................  N/A.
 10,000 people) c.                    after promulgation of
                                      LT2ESWTR.
--------------------------------------------------------------------------------------------------------------------------------------------------------
a Public water systems may use equivalent previously collected (grandfathered) data to meet LT2ESWTR requirements. See section IV.A.1.d for details.
b Public water systems may sample more frequently (e.g., twice-per-month, once-per-week).
c Small systems must monitor for Cryptosporidium for one year, beginning 6 months after completion of E. coli monitoring, if the E. coli annual mean
  concentration exceeds 10/100 mL for systems using lakes/reservoir sources or 50/100 mL for systems using flowing stream sources.
N/A = Not applicable. No monitoring required.

Sampling Location
    Source water samples must be representative of the intake to the 
filtration plant. Generally, sampling must be performed individually 
for each plant that treats a surface water source. However, where 
multiple plants receive all of their water from the same influent 
(e.g., multiple plants draw water from the same pipe), the same set of 
monitoring results may be applicable to each plant. Typically, samples 
must be collected prior to any treatment, with exceptions for certain 
pretreatment processes. Directions on sampling location for plants 
using off-stream storage, presedimentation, and bank filtration are 
provided in section IV.C.
    Systems with plants that use multiple water sources at the same 
time must collect samples from a tap where the sources are combined 
prior to treatment if available. If a blended source tap is not 
available, systems must collect samples from each source and either 
analyze a weighted composite (blended) sample or analyze samples from 
each source separately and determine a weighted average of the results.
Sampling Schedule
    Large systems must submit a sampling schedule to EPA within 3 
months after promulgation of the LT2ESWTR. Small systems must submit a 
sampling schedule for E. coli monitoring to their primacy agency within 
27 months after rule promulgation; small systems required to monitor 
for Cryptosporidium must submit a Cryptosporidium sampling schedule 
within 45 months after promulgation. The sampling schedules must 
specify the calendar date on which the system will collect each sample 
required under the LT2ESWTR. Scheduled sampling dates should be evenly 
distributed throughout the monitoring period, but may be arranged to 
accommodate holidays, weekends, and other events when collecting or 
analyzing a sample would be problematic.
    Systems must collect samples within 2 days before or 2 days after a 
scheduled sampling date. If a system does not sample within this 5-day 
window, the system will incur a monitoring violation unless either of 
the following two conditions apply:

    (1) If extreme conditions or situations exist that may pose 
danger to the sample collector, or which are unforeseen or cannot be 
avoided and which cause the system to be unable to sample in the 
required time frame, the system must sample as close to the required 
date as feasible and submit an explanation for the alternative 
sampling date with the analytical results.
    (2) Systems that are unable to report a valid Cryptosporidium 
analytical result for a scheduled sampling date due to failure to 
comply with analytical method quality control requirements 
(described in section IV.K) must collect a replacement sample within 
14 days of being notified by the laboratory or the State that a 
result cannot be reported for that date. Systems must submit an 
explanation for the replacement sample with the analytical results. 
Where possible, the replacement sample collection date should not 
coincide with any other scheduled LT2ESWTR sampling dates.

Approved Analytical Methods and Laboratories
    To ensure the quality of LT2ESWTR monitoring data, today's proposal 
requires systems to use approved methods for Cryptosporidium, E. coli, 
and turbidity analyses (see section IV.K for sample analysis 
requirements), and to have these analyses performed by approved 
laboratories (described in section IV.L).
Reporting
    Because source water monitoring by large systems will begin 6 
months after promulgation of the LT2ESWTR, EPA is proposing that 
monitoring results for large systems be reported directly to the Agency 
though an electronic data system (described in section IV.J), similar 
to the approach currently used under the Unregulated Contaminants 
Monitoring Rule (64 FR 50555, September 17, 1999) (USEPA 1999c). Small 
systems will report data to EPA or States, depending on whether States 
have assumed primacy for the LT2ESWTR.
Previously Collected Monitoring Results
    EPA is proposing to allow systems to use previously collected 
(i.e., grandfathered) Cryptosporidium monitoring data to meet LT2ESWTR 
monitoring requirements if the data are equivalent to data that will be 
collected under the rule (e.g., sample volume, sampling frequency, 
analytical method quality control). Criteria for acceptance of 
previously collected data are specified in section IV.A.1.d.
Providing Additional Treatment Instead of Monitoring
    Filtered systems are not required to conduct source water 
monitoring under the LT2ESWTR if the system currently provides or will 
provide a total of at least 5.5 log of treatment for Cryptosporidium, 
equivalent to meeting the treatment requirements of Bin 4 as shown in 
Table IV-4 (i.e., the maximum required in today's proposal). Systems 
must notify EPA or the State not later than the date the system is 
otherwise required to submit a sampling schedule for monitoring and 
must install and operate technologies to provide a total of at least 
5.5 log of treatment for Cryptosporidium by the applicable date in 
Table IV-23. Any filtered system that fails to complete LT2ESWTR 
monitoring requirements must meet the treatment requirements for Bin 4.
Ongoing Source Assessment and Second Round of Monitoring
    Because LT2ESWTR treatment requirements are related to the degree 
of source water contamination, today's proposal contains provisions to 
assess changes in a system's source water

[[Page 47667]]

quality following initial risk bin classification. These provisions 
include source water assessment during sanitary surveys and a second 
round of monitoring.
    Under 40 CFR 142.16(b)(3)(i), source water is one of the components 
that States must address during the sanitary surveys that are required 
for surface water systems. These sanitary surveys must be conducted 
every 3 years for community systems and every 5 years for non-community 
systems. EPA is proposing that if the State determines during the 
sanitary survey that significant changes have occurred in the watershed 
that could lead to increased contamination of the source water, the 
State may require systems to implement specific actions to address the 
contamination. These actions include implementing options from the 
microbial toolbox discussed in section IV.C.
    EPA is proposing that systems conduct a second round of source 
water monitoring, beginning six years after systems are initially 
classified in LT2ESWTR risk bins. To prepare for this second round of 
monitoring, the Advisory Committee recommended that EPA initiate a 
stakeholder process four years after large systems complete initial bin 
classification. The purpose of the stakeholder process would be to 
review risk information, and to determine the appropriate analytical 
method, monitoring frequency, monitoring location, and other criteria 
for the second round of monitoring.
    If EPA does not modify LT2ESWTR requirements through issuing a new 
regulation prior to the second round of monitoring, systems must carry 
out this monitoring according to the requirements that apply to the 
initial round of source water monitoring. Moreover, systems will be 
reclassified in LT2ESWTR risk bins based on the second round monitoring 
results and using the criteria specified in this section for initial 
bin classification. However, if EPA changes the LT2ESWTR risk bin 
structure to reflect a new analytical method or new risk information, 
systems will undergo a site specific risk characterization in 
accordance with the revised rule.

c. Treatment Requirements

    i. Bin classification. Under the proposed LT2ESWTR, surface water 
systems that use filtration will be classified in one of four 
Cryptosporidium concentration categories (bins) based on the results of 
source water monitoring. As shown in Table IV-2, bin classification is 
determined by averaging the Cryptosporidium concentrations measured for 
individual samples.

       Table IV-2.-- Bin Classification Table for Filtered Systems
------------------------------------------------------------------------
      If your average Cryptosporidium       Then your bin classification
         concentration 1 is . . .                     is . . .
------------------------------------------------------------------------
Cryptosporidium <0.075/L..................  Bin 1.
0.075/L <= Cryptosporidium < 1.0/L........  Bin 2.
1.0/L <= Cryptosporidium < 3.0/L..........  Bin 3.
Cryptosporidium = 3.0/L........  Bin 4.
------------------------------------------------------------------------
\1\ All concentrations shown in units of oocysts/L

    The approach that systems will use to average individual sample 
concentrations to determine their bin classification depends on the 
number of samples collected and the length of the monitoring period. 
Systems serving at least 10,000 people are required to monitor for 24 
months, and their bin classification must be based on the following:
    (1) Highest twelve month running annual average for monthly 
sampling, or
    (2) two year mean if system conducts twice-per-month or more 
frequent sampling for 24 months (i.e., at least 48 samples).
    Systems serving fewer than 10,000 people are required to collect 24 
Cryptosporidium samples over 12 months if they exceed the E. coli 
trigger level, and their bin classification must be based on the mean 
of the 24 samples. As noted earlier, systems that fail to complete the 
required Cryptosporidium monitoring will be classified in Bin 4.
    When determining LT2ESWTR bin classification, systems must 
calculate individual sample concentrations using the total number of 
oocysts counted, unadjusted for method recovery, divided by the volume 
assayed (see section IV.K for details). As described in Section IV.A.2, 
the ranges of Cryptosporidium concentrations that define LT2ESWTR bins 
reflect consideration of analytical method recovery and the percent of 
Cryptosporidium oocysts that are infectious. Consequently, sample 
analysis results will not be adjusted for these factors.
    ii. Credit for treatment in place. A key parameter in determining 
additional Cryptosporidium treatment requirements is the credit that 
plants receive for treatment currently provided (i.e., treatment in 
place). For baseline treatment requirements established by the SWTR, 
IESWTR, and LT1ESWTR that apply uniformly to filtered systems, the 
Agency has awarded credit based on the minimum removal that plants will 
achieve. Specifically, in the IESWTR and LT1ESWTR, EPA determined that 
filtration plants, including conventional, direct, slow sand, and DE, 
meeting the required filter effluent turbidity criteria will achieve at 
least 2 log removal of Cryptosporidium. Consequently, these plants were 
awarded a 2 log Cryptosporidium removal credit, which equals the 
maximum treatment required under these regulations.
    The LT2ESWTR will supplement existing regulations by mandating 
additional treatment at certain plants based on site specific 
conditions (i.e., source water Cryptosporidium level). When assessing 
the need for additional treatment beyond baseline requirements for 
higher risk systems, the Agency has determined that it is appropriate 
to consider the average removal efficiency achieved by treatment 
plants. As described in section III.D, EPA has concluded that 
conventional, slow sand, and DE plants in compliance with the SWTR, 
IESWTR, and LT1ESWTR achieve an average Cryptosporidium reduction of 3 
log. Consequently, EPA is proposing to award these plants a 3 log 
credit towards Cryptosporidium treatment requirements under the 
LT2ESWTR. As noted previously, this approach is consistent with the 
Stage 2 M-DBP Agreement in Principle.
    For other types of filtration plants, treatment credit under the 
LT2ESWTR differs. Conventional treatment is defined in 40 CFR 141.2 as 
a series of processes including coagulation, flocculation, 
sedimentation, and filtration, with sedimentation defined as a process 
for removal of solids before filtration by gravity or separation. Thus, 
plants with separation (i.e., clarification) processes other than 
gravity sedimentation between flocculation and filtration, such as DAF, 
may be regarded as conventional treatment for purposes of awarding 
treatment credit under the LT2ESWTR. However, for direct filtration 
plants, which lack a sedimentation process, EPA is proposing a 2.5 log 
Cryptosporidium removal credit. Studies that support awarding direct 
filtration plants less treatment credit than conventional plants are 
summarized in section III.D.
    EPA is unable to estimate an average log removal for other 
filtration technologies like membranes, bag filters, and cartridge 
filters, due to variability among products. As a result, credit for 
these devices must be determined by the State, based on product 
specific testing described in section IV.C or other criteria approved 
by the State.

[[Page 47668]]

    Table IV-3 presents the credit proposed for different types of 
plants towards LT2ESWTR Cryptosporidium treatment requirements. As 
described in section IV.C.18, a State may award greater credit to a 
system that demonstrates through a State-approved protocol that it 
reliably achieves a higher level of Cryptosporidium removal. 
Conversely, a State may award less credit to a system where the State 
determines, based on site specific information, that the system is not 
achieving the degree of Cryptosporidium removal indicated in Table IV-
3.

                  Table IV-3.--Cryptosporidium Treatment Credit Towards LT2ESWTR Requirements 1
----------------------------------------------------------------------------------------------------------------
                                     Conventional
                                       treatment                             Slow sand or         Alternative
           Plant type                  (includes       Direct filtration  diatomaceous earth      filtration
                                      softening)                              filtration         technologies
----------------------------------------------------------------------------------------------------------------
Treatment credit................  3.0 log...........  2.5 log...........  3.0 log...........  Determined by
                                                                                               State 2.
----------------------------------------------------------------------------------------------------------------
\1\ Applies to plants in full compliance with the SWTR, IESWTR, and LT1ESWTR as applicable
\2\ Credit must be determined through product or site specific assessment

    iii. Treatment requirements associated with LT2ESWTR bins
    The treatment requirements associated with LT2ESWTR risk bins are 
shown in Table IV-4. The total Cryptosporidium treatment required for 
Bins 2, 3, and 4 is 4.0 log, 5.0 log, and 5.5 log, respectively. For 
conventional (including softening), slow sand, and DE plants that 
receive 3.0 log credit for compliance with current regulations, 
additional Cryptosporidium treatment of 1.0 to 2.5 log is required when 
classified in Bins 2-4. Direct filtration plants that receive 2.5 log 
credit for compliance with current regulations must achieve 1.5 to 3.0 
log of additional Cryptosporidium treatment in Bins 2-4.
    For systems using alternative filtration technologies, such as 
membranes or bag/cartridge filters, and classified in Bins 2-4, the 
State must determine additional treatment requirements based on the 
credit awarded to a particular technology. The additional treatment 
must be such that plants classified in Bins 2, 3, and 4 achieve the 
total required Cryptosporidium reductions of 4.0, 5.0, and 5.5 log, 
respectively.

                       Table IV-4.--Treatment Requirements Per LT2ESWTR Bin Classification
----------------------------------------------------------------------------------------------------------------
                                    And you use the following filtration treatment in full compliance with the
                                    SWTR, IESWTR, and LT1ESWTR (as applicable), then your additional treatment
                                                              requirements are . . .
                                 -------------------------------------------------------------------------------
 If your bin classification is .     Conventional
               . .                    filtration                             Slow sand or         Alternative
                                       treatment       Direct filtration  diatomaceous earth      filtration
                                       (includes                              filtration         technologies
                                      softening)
----------------------------------------------------------------------------------------------------------------
Bin 1...........................  No additional       No additional       No additional       No additional
                                   treatment.          treatment.          treatment.          treatment.
Bin 2...........................  1 log treatment     1.5 log treatment   1 log treatment     As determined by
                                   \1\.                \1\.                \1\.                the State 1, 3.
Bin 3...........................  2 log treatment     2.5 log treatment   2 log treatment     As determined by
                                   \2\.                \2\.                \2\.                the State 2, 4.
Bin 4...........................  2.5 log treatment   3 log treatment     2.5 log treatment   As determined by
                                   \2\.                \2\.                \2\.                the State 2, 5.
----------------------------------------------------------------------------------------------------------------
\1\ Systems may use any technology or combination of technologies from the microbial toolbox.
\2\ Systems must achieve at least 1 log of the required treatment using ozone, chlorine dioxide, UV, membranes,
  bag/cartridge filters, or bank filtration.
\3\ Total Cryptosporidium removal and inactivation must be at least 4.0 log.
\4\ Total Cryptosporidium removal and inactivation must be at least 5.0 log.
\5\ Total Cryptosporidium removal and inactivation must be at least 5.5 log.

    Plants can achieve additional Cryptosporidium treatment credit 
through implementing pretreatment processes like presedimentation or 
bank filtration, by developing a watershed control program, and by 
applying additional treatment steps like UV, ozone, chlorine dioxide, 
and membranes. In addition, plants can receive additional credit for 
existing treatment through achieving very low filter effluent turbidity 
or through a demonstration of performance. Section IV.C presents 
criteria for awarding Cryptosporidium treatment credit to a host of 
treatment and control options, including those listed here and others, 
which are collectively termed the ``microbial toolbox''.
    Systems in Bin 2 can meet additional Cryptosporidium treatment 
requirements through using any option or combination of options from 
the microbial toolbox. In Bins 3 and 4, systems must achieve at least 1 
log of the additional treatment requirement through using ozone, 
chlorine dioxide, UV, membranes, bag filtration, cartridge filtration, 
or bank filtration.
    d. Use of previously collected data. Today's proposal allows 
systems with previously collected Cryptosporidium data (i.e., data 
collected prior to the required start of monitoring under the LT2ESWTR) 
that are equivalent in sample number, frequency, and data quality to 
data that will be collected under the LT2ESWTR to use those data in 
lieu of conducting new monitoring. Specifically, EPA is proposing that 
Cryptosporidium sample analysis results collected prior to promulgation 
of the LT2ESWTR must meet the following criteria to be used for bin 
classification:
    [sbull] Samples were analyzed by laboratories using validated 
versions of EPA Methods 1622 or 1623 and meeting the quality control 
criteria specified in these methods (USEPA 1999a, USEPA 1999b, USEPA 
2001e, USEPA 2001f).
    [sbull] Samples were collected no less frequently than each 
calendar month on a regular schedule, beginning no earlier than January 
1999 (when EPA Method 1622 was first released as an interlaboratory-
validated method).
    [sbull] Samples were collected in equal intervals of time over the 
entire collection period (e.g., weekly,

[[Page 47669]]

monthly). The allowances for deviations from a sampling schedule 
specified under IV.A.1.b for LT2ESWTR monitoring apply to grandfathered 
data.
    [sbull] Samples were collected at the correct location as specified 
for LT2ESWTR monitoring. Systems must report the use of bank 
filtration, presedimentation, and raw water off-stream storage during 
sampling.
    [sbull] For each sample, the laboratory analyzed at least 10 L of 
sample or at least 2 mL of packet pellet volume or as much volume as 
two filters could accommodate before clogging (applies only to filters 
that have been approved by EPA for use with Methods 1622 and 1623).
    [sbull] The system must certify that it is reporting all 
Cryptosporidium monitoring results generated by the system during the 
time period covered by the previously collected data. This applies to 
samples that were (a) collected from the sampling location used for 
LT2ESWTR monitoring, (b) not spiked, and (c) analyzed using the 
laboratory's routine process for Method 1622 or 1623 analyses.
    [sbull] The system must also certify that the samples were 
representative of a plant's source water(s) and the source water(s) 
have not changed.
    If a system has at least two years of Cryptosporidium data 
collected before promulgation of the LT2ESWTR and the system does not 
intend to conduct new monitoring under the rule, the system must submit 
the data and the required supporting documentation to EPA no later than 
two months following promulgation of the rule. EPA will notify the 
system within four months following LT2ESWTR promulgation as to whether 
the data are sufficient for bin determination. Unless EPA notifies the 
system in writing that the previously collected data are sufficient for 
bin determination, the system must conduct source water Cryptosporidium 
monitoring as described in section IV.A.1.b of this preamble.
    If a system intends to grandfather fewer than two years of 
Cryptosporidium data, or if a system intends to grandfather 2 or more 
years of previously collected data and also to conduct new monitoring 
under the rule, the system must submit the data and the required 
supporting documentation to EPA no later than eight months following 
promulgation of the rule. Systems must conduct monitoring as described 
in section IV.A.1.b until EPA notifies the system in writing that it 
has at least 2 years of acceptable data. See section IV.J for 
additional information on reporting requirements associated with 
previously collected data.
2. How Was This Proposal Developed?
    The monitoring and treatment requirements for filtered systems 
proposed under the LT2ESWTR stem from the data and analyses described 
in this section and reflect recommendations made by the Stage 2 M-DBP 
Federal Advisory Committee (65 FR 83015) (USEPA 2000a).
    a. Basis for targeted treatment requirements. Under the IESWTR, EPA 
established an MCLG of zero for Cryptosporidium at the genus level 
based on the public health risk associated with this pathogen. The 
IESWTR included a 2 log treatment technique requirement for medium and 
large filtered systems that controlled for Cryptosporidium as close to 
the MCLG as was then deemed technologically feasible, taking costs into 
consideration. The LT1ESWTR extended this requirement to small systems. 
Given the advances that have occurred subsequent to the IESWTR in 
available technology to measure and treat for Cryptosporidium, a key 
question for the LT2ESWTR was the extent to which Cryptosporidium 
should be further controlled to approach the MCLG of zero, considering 
technical feasibility, costs, and potential risks from DBPs.
    The data and analysis presented in Section III of this preamble 
suggest wide variability in possible risk from Cryptosporidium among 
public water systems. This variability is largely due to three factors: 
(1) The broad distribution of Cryptosporidium occurrence levels among 
source waters, (2) disparities in the efficacy of treatment provided by 
plants, and (3) differences in the infectivity among Cryptosporidium 
isolates. EPA and the Advisory Committee considered this wide range of 
possible risks and the desire to address systems where the 2 log 
removal requirement established by the IESWTR and LT1ESWTR may not 
provide adequate public health protection.
    A number of approaches were evaluated for furthering control of 
Cryptosporidium. One approach was to require all systems to provide the 
same degree of additional treatment for Cryptosporidium (i.e., beyond 
that required by the IESWTR and LT1ESWTR). This approach could ensure 
that most systems, including those with poor quality source water, 
would be adequately protective. The uniformity of this approach has the 
advantage of minimizing transactional costs for determining what must 
be done by a particular system to comply. However, a significant 
downside is that it may require more treatment, with consequent costs, 
than is needed by many systems with low source water Cryptosporidium 
levels. In addition, there were concerns with the feasibility of 
requiring almost all surface water treatment plants to install 
additional treatment processes for Cryptosporidium.
    A second approach was to base additional treatment requirements on 
a plant's source water Cryptosporidium level. Under this approach, 
systems monitor their source water for Cryptosporidium, and additional 
treatment is required only from those systems that exceed specified 
oocyst concentrations. This has the advantage of targeting additional 
public health protection to those systems with higher vulnerability to 
Cryptosporidium, while avoiding the imposition of higher treatment 
costs on systems with the least contaminated source water. In 
consideration of these advantages, the Advisory Committee recommended 
and EPA is proposing this second approach for filtered systems under 
the LT2ESWTR.
    b. Basis for bin concentration ranges and treatment requirements. 
The proposed LT2ESWTR will classify plants into different risk bins 
based on the source water Cryptosporidium level, and the bin 
classification will determine the extent to which additional treatment 
beyond IESWTR and LT1ESWTR is required. Two questions were central in 
developing the proposed bin concentration ranges and additional 
treatment requirements:
    [sbull] What is the risk associated with a given level of 
Cryptosporidium in a drinking water source?
    [sbull] What degree of additional treatment should be required for 
a given source water Cryptosporidium level?
    This section addresses these two questions by first summarizing how 
EPA assessed the risk associated with Cryptosporidium in drinking 
water, followed by a description of how EPA and the Advisory Committee 
used this type of information in identifying LT2ESWTR bin concentration 
ranges and treatment requirements. For additional information on these 
topics, see Economic Analysis for the LT2ESWTR (USEPA 2003a).
    i. What is the risk associated with a given level of 
Cryptosporidium in a drinking water source? The risk of infection from 
Cryptosporidium in drinking water is a function of infectivity (i.e., 
dose-response associated with ingestion) and exposure. Section III.B 
summarizes available data on Cryptosporidium infectivity. EPA conducted 
a meta-analysis of reported infection rates from human feeding

[[Page 47670]]

studies with 3 Cryptosporidium isolates. This analysis produced an 
estimate for the mean probability of infection given a dose of one 
oocyst near 0.09 (9%), with 10th and 90th percentile confidence values 
of 0.011 and 0.22, respectively.
    Exposure to Cryptosporidium depends on the concentration of oocysts 
in the source water, the efficiency of treatment plants in removing 
oocysts, and the volume of water ingested (exposure can also occur 
through interactions with infected individuals). Based on data 
presented in section III.D, EPA has estimated that filtration plants in 
compliance with the IESWTR or LT1ESWTR reduce source water 
Cryptosporidium levels by 2 to 5 log (99% to 99.999%), with an average 
reduction near 3 log. For drinking water consumption, EPA uses a 
distribution, derived from the United States Department of 
Agriculture's (USDA) 1994-96 Continuing Survey of Food Intakes by 
Individuals, with a mean value of 1.2 L/day. Average annual days of 
exposure to drinking water in CWS, non-transient non-community water 
systems (NTNCWS), and transient non-community water systems (TNCWS) are 
estimated at 350 days, 250 days, and 10 days, respectively. (The 
Economic Analysis for the LT2ESWTR (USEPA 2003a) provides details on 
all parameters listed here, as well as morbidity, mortality, and other 
risk factors.)
    Using an estimate of 1.2 L/day consumption and a mean probability 
of infection of 0.09 for one oocyst ingested, the daily risk of 
infection (DR) is as follows:

DR = (oocysts/L in source water) x (percent remaining after treatment) 
x (1.2 L/day) x (0.09).

    The annual risk (AR) of infection for a CWS is

AR = 1-(1-DR)\350\

where 350 represents days of exposure in a CWS.
    Table IV-5 presents estimates of the mean annual risk of infection 
by Cryptosporidium in CWSs for selected source water infectious oocyst 
concentrations and filtration plant removal efficiencies.

   Table IV-5.--Annual Risk of Cryptosporidium Infection in CWSs That
  Filter, as a Function of Source Water Infectious Oocyst Concentration
                        and Treatment Efficiency
------------------------------------------------------------------------
  Source water     Mean annual risk of infection for different levels of
  concentration           treatment efficiency (log removal) \1\
   (infectious   -------------------------------------------------------
   oocysts per                                                        5
     liter)            2 log            3 log            4 log       log
------------------------------------------------------------------------
0.0001            3.8E-05          3.8E-06          3.8E-07          3.8
                                                                     E-0
                                                                      8
0.001             3.7E-04          3.8E-05          3.8E-06          3.8
                                                                     E-0
                                                                      7
0.01              3.7E-03          3.7E-04          3.8E-05          3.8
                                                                     E-0
                                                                      6
0.1               3.7E-02          3.7E-03          3.7E-04          3.8
                                                                     E-0
                                                                      5
1                 0.31             3.7E-02          3.7E-03          3.7
                                                                     E-0
                                                                      4
10                0.89             0.31             3.7E-02          3.7
                                                                     E-0
                                                                     3
------------------------------------------------------------------------
\1\ Scientific notation (E-x) designates 10-x

    For example, Table IV-5 shows that if a filtration plant had a mean 
concentration of infectious Cryptosporidium in the source water of 0.01 
oocysts/L, and the filtration plant averaged 3 log removal, the mean 
annual risk of infection by Cryptosporidium is estimated as 3.7 x 
10-4 (3.7 infections per 10,000 consumers).
    ii. What degree of additional treatment should be required for a 
given source water Cryptosporidium level? In order to develop targeted 
treatment requirements for the LT2ESWTR, it was necessary to identify a 
source water Cryptosporidium level above which additional treatment by 
filtered systems would be required. Based on the type of risk 
information shown in Table IV-5, EPA and Advisory Committee 
deliberations focused on mean source water Cryptosporidium 
concentrations in the range of 0.01 to 0.1 oocysts/L as appropriate 
threshold values for prescribing additional treatment.
    Analytical method and sampling constraints were a significant 
factor in setting the specific Cryptosporidium level that triggers 
additional treatment by filtered systems. The number of samples that 
systems can be required to analyze for Cryptosporidium is limited. 
Consequently, if the bin threshold concentration for additional 
treatment was set near 0.01 oocysts/L, systems could exceed this level 
due to a very low number of oocysts being detected. For example, if 
systems took monthly 10 L samples and bin classification was based on a 
maximum running annual average, then a system would exceed a mean 
concentration of 0.01 oocysts/L by counting only 2 oocysts in 12 
samples. Given the variability associated with Cryptosporidium 
analytical methods, the Advisory Committee did not support requiring 
additional treatment for filtered systems based on so few counts.
    Another concern related to analytical method limitations was 
systems being misclassified in a lower bin. For example, if a system 
had a true mean concentration at or just above 0.1 oocysts/L, the mean 
that the system would determine through monitoring might be less than 
0.1 oocyst/L. Thus, if the bin threshold for additional treatment was 
set at 0.1 oocysts/L, a number of systems with true mean concentrations 
above this level would be misclassified in the lower bin with no 
additional treatment required. This type of error, described in more 
detail in the next section, is a function of the number of samples 
collected and variability in method performance.
    In consideration of the available information on Cryptosporidium 
risk, as well as the performance and feasibility of analytical methods, 
EPA is proposing that the source water threshold concentration for 
requiring additional Cryptosporidium treatment by filtered systems be 
established at a mean level of 0.075 oocysts/L. This is the level 
recommended by the Advisory Committee, and it affords a high likelihood 
that systems with true mean Cryptosporidium concentrations of 0.1 
oocysts/L or higher will provide additional treatment under the rule.
    Beyond identifying this first threshold, it was also necessary to 
determine Cryptosporidium concentrations that would demarcate higher 
risk bins. With respect to the concentration range that each bin should 
comprise, EPA and the Advisory Committee dealt with two opposing 
factors: bin misclassification and equitable risk reduction.
    As described in the next section, a monthly monitoring program 
involving EPA Methods 1622 or 1623 can characterize a system's mean 
Cryptosporidium concentration within a

[[Page 47671]]

0.5 log (factor of 3.2) margin with a high degree of accuracy. However, 
the closer a system's true mean concentration is to a bin boundary, the 
greater the likelihood that the system will be misclassified into the 
wrong bin due to limitations in sampling and analysis. Accordingly, by 
establishing bins that cover a wide concentration range, the likelihood 
of system misclassification is reduced.
    However, a converse factor relates to equitable protection from 
risk. Because identical treatment requirements will apply to all 
systems in the same bin, systems at the higher concentration end of a 
bin will achieve less risk reduction relative to their source water 
pathogen levels than systems at the lower concentration end of a bin. 
Thus, bins with a narrow concentration range provide a more uniform 
level of public health protection.
    In balancing these factors and to account for the wide range of 
possible source water concentrations among different systems as 
indicated by Information Collection Rule and ICRSS data, the Advisory 
Committee recommended and EPA is proposing a second bin threshold at a 
mean level of 1.0 oocysts/L and a third bin threshold at a mean level 
of 3.0 oocysts/L. Information Collection Rule and ICRSS data indicate 
that few, if any, systems would measure mean Cryptosporidium 
concentrations greater than 3.0 oocysts/L, so there was not a need to 
establish a bin threshold above this value. Thus, the LT2ESWTR proposal 
includes the following four bins for classifying filtered systems: Bin 
1: <0.075/L; Bin 2: =0.075 to <1.0/L; Bin 3: 
=1.0/L to <3.0/L; and Bin 4: =3.0/L (oocysts/L).
    With respect to additional Cryptosporidium treatment for systems in 
Bins 2-4, values were considered ranging from 0.5 to 2.5 log and 
greater. As recommended by the Advisory Committee, EPA is proposing 1.0 
log additional treatment for conventional plants in Bin 2. This level 
of treatment will ensure that systems classified in Bin 2 will achieve 
treated water Cryptosporidium levels comparable to systems in Bin 1, 
the lowest risk bin. In contrast, if systems in Bin 2 provided only 0.5 
log additional treatment then those systems with mean source water 
concentrations in the upper part of Bin 2 would have higher levels of 
Cryptosporidium in their finished water than systems in Bin 1.
    In consideration of the much greater potential vulnerability of 
systems in the highest risk bins, the Advisory Committee recommended 
additional treatment requirements of 2.0 log and 2.5 log for 
conventional plants in Bins 3 and 4, respectively. The Agency concurs 
with these recommendations and has incorporated them in today's 
proposal.
    An important aspect of the proposed additional treatment 
requirements is that they are based, in part, on the current level of 
treatment provided by filtration plants. As noted earlier, the Advisory 
Committee assumed when developing its recommendations that conventional 
treatment plants in compliance with the IESWTR achieve an average of 3 
log removal of Cryptosporidium. EPA has determined that available data, 
discussed in section III.D, support this assumption and has proposed a 
3 log Cryptosporidium treatment credit for conventional plants under 
the LT2ESWTR. Thus, the additional treatment requirements for 
conventional plants in Bins 2, 3, and 4 translate to total requirements 
of 4.0, 5.0, and 5.5 log, respectively.
    The Advisory Committee did not address additional treatment 
requirements for plants with treatment trains other than conventional, 
but recommended that EPA address such plants in the proposed LT2ESWTR 
and take comment. Based on treatment studies summarized in section 
III.D, EPA has concluded that plants with slow sand or DE filtration 
are able to achieve 3 log or greater removal of Cryptosporidium when in 
compliance with the IESWTR or LT1ESWTR. Because these plants can 
achieve comparable levels of performance to conventional treatment 
plants, EPA is proposing that slow sand and DE filtration plants also 
apply 1 to 2.5 log of additional treatment when classified in Bins 2-4.
    Direct filtration differs from conventional treatment in that it 
does not include sedimentation or an equivalent clarification process 
prior to filtration. As described in section III.D, EPA has concluded 
that a sedimentation process can consistently achieve 0.5 log or 
greater removal of Cryptosporidium. The Agency is proposing that direct 
filtration plants in compliance with the IESWTR or LT1ESWTR receive a 
2.5 log Cryptosporidium removal credit towards LT2ESWTR requirements. 
Accordingly, proposed additional treatment requirements for direct 
filtration plants in bins 2, 3, and 4 are 1.5 log, 2.5 log, and 3 log, 
respectively.
    Section IV.C of this notice describes proposed criteria for 
determining Cryptosporidium treatment credits for other filtration 
technologies like membranes, bag filters, and cartridge filters. Due to 
the proprietary and product specific nature of these filtration 
devices, EPA is not able to propose a generally applicable credit for 
them. Rather, the criteria in section IV.C focus on challenge testing 
to establish treatment credit. Systems using these technologies that 
are classified in Bins 2-4 must work with their States to assess 
appropriate credit for their existing treatment trains. This will 
determine the level of additional treatment necessary to achieve the 
total treatment requirements for their assigned bins. EPA has developed 
guidance on challenge testing of bag and cartridge filters and 
membranes, which is available in draft form in the docket (http://www.epa.gov/edocket/).
    In order to give systems flexibility in choosing strategies to meet 
additional Cryptosporidium treatment requirements, the Advisory 
Committee identified a number of management and treatment options, 
collectively called the microbial toolbox. The toolbox, which is 
described in section IV.C, contains components relating to watershed 
control, intake management, pretreatment, additional filtration 
processes, inactivation, and demonstrations of enhanced performance.
    As recommended by the Advisory Committee, EPA is proposing that 
systems in Bin 2 can meet additional Cryptosporidium treatment 
requirements under the LT2ESWTR using any component or combination of 
components from the microbial toolbox. However, systems in Bins 3 and 4 
must achieve at least 1 log of the additional treatment requirement 
using inactivation (UV, ozone, chlorine dioxide), membranes, bag 
filters, cartridge filters, or bank filtration. These specific control 
measures are proposed due to their ability to serve as significant 
additional treatment barriers for systems with high levels of 
pathogens.
    c. Basis for source water monitoring requirements. The goal of 
monitoring under the LT2ESWTR is to correctly classify filtration 
plants into the four LT2ESWTR risk bins. The proposed sampling 
frequency, time frame, and averaging procedure for bin classification 
are intended to ensure that systems are accurately assigned to 
appropriate risk bins while limiting the burden of monitoring costs. 
The basis for the proposed monitoring requirements for large and small 
systems is presented in the following discussion.
    i. Systems serving at least 10,000 people.
Sample Number and Frequency
    Systems serving at least 10,000 people have two options for 
sampling under the

[[Page 47672]]

LT2ESWTR: (1) They can collect 24 monthly samples over a 2 year period 
and calculate their bin classification using the highest 12 month 
running annual average, or (2) They can collect 2 or more samples per 
month over the 2 year period and use the mean of all samples for bin 
classification.
    These proposed requirements reflect recommendations by the Advisory 
Committee and are based on analyses of misclassification rates 
associated with different monitoring programs that were considered. EPA 
is concerned about systems with high concentrations of Cryptosporidium 
being misclassified in lower bins as well as systems with low 
concentrations being misclassified in higher bins. The first type of 
error could lead to systems not providing an adequate level of 
treatment while the second type of error could lead to systems 
incurring additional costs for unnecessary treatment.
    A primary way that EPA analyzed misclassification rates was by 
considering the likelihood that a system with a true mean 
Cryptosporidium concentration that is a factor of 3.2 (0.5 log) above 
or below a bin boundary would be assigned to the wrong bin.
    Probabilities were assessed for two cases:
    [sbull] False negative: a system with a mean concentration of 0.24 
oocysts/L (i.e., factor of 3.2 above the Bin 1 boundary of 0.075 
oocysts/L) is misclassified low in Bin 1.
    [sbull] False positive: a system with a mean concentration of 0.024 
oocysts/L (i.e., factor of 3.2 below the Bin 1 boundary of 0.075 
oocysts/L) is misclassified high in Bin 2.
    Table IV-6 provides false negative and false positive rates as 
defined previously for different approaches to monitoring and bin 
classification that were evaluated. Results are shown for the following 
approaches:
    [sbull] 48 samples with bin assignment based on arithmetic mean 
(i.e., average of all samples).
    [sbull] 24 samples with bin assignment based on highest 12 sample 
average, equivalent to the maximum running annual average (Max-RAA).
    [sbull] 24 samples with bin assignment based on arithmetic mean.
    [sbull] 12 samples with bin assignment based on the second highest 
sample result.
    [sbull] 8 samples with bin assignment based on the maximum sample 
result.
    These estimated misclassification rates were generated with a Monte 
Carlo analysis that accounted for the volume assayed, variation in 
source water Cryptosporidium occurrence, and variable method recovery. 
See Economic Analysis for the LT2ESWTR (USEPA 2003a) for details.

 Table IV-6.--False Positive and False Negative Rates for Monitoring and
             Binning Strategies Considered for the LT2ESWTR
                            [In percentages]
------------------------------------------------------------------------
                                                        False     False
                      Strategy                        positive  negative
                                                         \1\       \2\
------------------------------------------------------------------------
48 sample arithmetic mean...........................       1.7       1.4
24 sample Max-RAA...................................       5.3       1.7
24 sample arithmetic mean...........................       2.8       6.2
12 sample second highest............................        47       1.1
8 sample maximum....................................        66       1.0
------------------------------------------------------------------------
\1\ False positive rates calculated for systems with Cryptosporidium
  concentrations 0.5 log below the Bin 1 boundary of 0.075 oocysts/L.
\2\ False negative rates calculated for systems with Cryptosporidium
  concentrations 0.5 log above the Bin 1 boundary of 0.075 oocysts/L.

    The first two of these approaches, the 48 sample arithmetic mean 
and 24 sample Max-RAA, were recommended by the Advisory Committee and 
are proposed for bin classification under the LT2ESWTR because they 
have low false positive and false negative rates. As shown in Table IV-
6, these strategies have false negative rates of 1 to 2%, meaning there 
is a 98 to 99% likelihood that a plant with an oocyst concentration 0.5 
log above the Bin 1 boundary would be correctly assigned to Bin 2. The 
false positive rate is near 2% for the 48 sample arithmetic mean and 5% 
for the 24 sample Max-RAA. These rates indicate that a plant with an 
oocyst concentration 0.5 log below the Bin 1 boundary would have a 95 
to 98% probability of being correctly assigned to Bin 1. Bin 
misclassification rates across a wide range of concentrations are shown 
in Economic Analysis for the LT2ESWTR (USEPA 2003a).
    The 24 sample arithmetic mean had a slightly lower false positive 
rate than the 24 sample Max-RAA (2.8% vs. 5.3%) but the false negative 
rate of the arithmetic mean was almost 4 times higher. Consequently, a 
plant with a mean Cryptosporidium level above the Bin 1 boundary would 
be much more likely to be misclassified in Bin 1 using a 24 sample 
arithmetic mean than with a 24 sample Max-RAA. In order to increase the 
probability that systems with mean Cryptosporidium concentrations above 
0.075 oocysts/L will provide additional treatment, EPA is proposing 
that if only 24 samples are taken, the maximum 12 month running annual 
average must be used to determine bin assignment.
    Monitoring strategies involving only 12 and 8 samples were 
evaluated to determine if lower frequency monitoring could provide 
satisfactory bin classification. The results of this analysis indicate 
that these lower sample numbers are not adequate and could unfairly 
bias excessive treatment requirements. For example, results in Table 
IV-6 show that if plants were classified in bins based on the second 
highest of 12 samples or the highest of eight samples then low false 
negative rates could be achieved. A system with a mean Cryptosporidium 
level 0.5 log above the Bin 1 boundary would have a 99% chance of being 
appropriately classified in a bin requiring additional treatment under 
either strategy. However, the false positive rates associated with 
these low sample numbers are very high. A system with a mean oocyst 
concentration 0.5 log below the Bin 1 boundary would have a 47% 
probability of being incorrectly classified in Bin 2 using the second 
highest result among 12 samples, or a 66% likelihood of being 
misclassified in Bin 2 using the maximum result among 8 samples. Due to 
high false positive rates, these strategies are not proposed.
    EPA also evaluated lower frequency monitoring strategies that had 
lower false positive rates, such as bin classification based on the 
mean of 12 samples, the third highest result of 12 samples, and the 
second highest of 8 samples. Each of these strategies, though, had an 
unacceptably high false negative rate, meaning that many systems with 
mean oocyst concentrations greater than the Bin 1 boundary would be 
misclassified low in Bin 1. Consequently, these strategies are 
inconsistent with the public health goal of the LT2ESWTR for systems 
with mean levels above 0.075 oocysts/L to provide additional treatment.
    Increasing the number of samples used to compute the maximum 
running annual average above 24 also increased the number of annual 
averages computed, so it did not reduce the likelihood of false 
positives. Raising the number of samples used to compute an arithmetic 
mean above 48 did reduce bin misclassification rates, but the rates 
were already very small (1 to 2% for plants with levels 0.5 log above 
or below bin boundaries). For sources with Cryptosporidium 
concentrations very near or at bin boundaries, increasing the number of 
samples did not markedly improve the error rates, which remained near 
50% at the bin boundaries.
    In summary, EPA believes that the proposed sampling designs perform 
well for the purpose of classifying plants in LT2ESWTR risk bins and,

[[Page 47673]]

thereby, achieving the public health protection intended for the rule. 
More costly designs, involving more frequent sampling and analysis, 
provide only marginally improved performance. Less frequent sampling, 
though lower in cost, creates unacceptably high misclassification rates 
and would not provide for the targeted risk reduction goals of the 
rule.
No Adjustments for Method Recovery or Percent of Oocysts That Are 
Infectious
    Two considerations in using Cryptosporidium monitoring data to 
project risk are (1) Fewer than 100% of oocysts in a sample are 
recovered and counted by the analyst and (2) not all the oocysts 
measured with Methods 1622/23 are viable and capable of causing 
infection. These two factors are offsetting in sign, in that oocyst 
counts not adjusted for recovery tend to underestimate the true 
concentration, while the total oocyst count may overestimate the 
infectious concentration that presents a health risk. Based on 
information described in this section, EPA is proposing that 
Cryptosporidium monitoring results be used directly to assign systems 
to LT2ESWTR risk bins and not be adjusted for either factor.
    As described in section III.C, ICRSS matrix spike data indicate 
that average recovery of Cryptosporidium oocysts with Methods 1622/23 
in a national monitoring program will be about 40%. There is no similar 
direct measure of the fraction of environmental oocysts that are 
infectious, but information related to this value can be derived from 
two sources: (1) A study where samples were analyzed with both Method 
1623 and a cell culture-polymerase chain reaction (CC-PCR) test for 
oocyst infectivity, and (2) the structure of oocysts counted with 
Methods 1622 and 1623.
    LeChevallier et al. (2003) conducted a study in which six natural 
waters were frequently tested for Cryptosporidium using both Method 
1623 and a CC-PCR method to test for infectivity. Cryptosporidium 
oocysts were detected in 60 of 593 samples (10.1%) by Method 1623 and 
infectious oocysts were detected in 22 of 560 samples (3.9%) by the CC-
PCR procedure. Recovery efficiencies for the two methods were similar. 
According to the authors, these results suggest that approximately 37% 
(22/60) of the Cryptosporidium oocysts detected by Method 1623 were 
viable and infectious.
    In regard to oocyst structure, Cryptosporidium oocysts counted with 
Methods 1622/23 are characterized in one of three ways: (1) Internal 
structures, (2) amorphous structures, or (3) empty. Oocysts with 
internal structures are considered to have the highest likelihood of 
being infectious, while empty oocysts are believed to be non-viable 
(LeChevallier et al. 1997). During the ICRSS, 37% of the oocysts 
counted were characterized as having internal structures, 47% had 
amorphous structures, and 16% were empty. If it is assumed that empty 
oocysts could not be infectious, the mid-point value within the 
percentage range of counted oocysts that could have been infectious is 
42%.
    After considering this type of information, the Advisory Committee 
recommended that monitoring results not be adjusted upward for percent 
recovery, nor adjusted downward to account for the fraction of oocysts 
that are not infectious. While it is not possible to establish a 
precise value for either factor in individual samples, the data suggest 
that they may be of similar magnitude. EPA concurs with this 
recommendation and is proposing that systems be classified in bins 
under the LT2ESWTR using the total Cryptosporidium oocyst count, 
uncorrected for recovery, as measured using EPA Method 1622/23. The 
proposed LT2ESWTR risk bins are constructed to reflect this approach.
Data Collection To Support Use of a Microbial Indicator by Small 
Systems
    As described in the next section, small systems will monitor for an 
indicator, currently proposed to be E. coli, to determine if they are 
required to sample for Cryptosporidium. The proposed E. coli levels 
that will trigger Cryptosporidium monitoring are based on Information 
Collection Rule and ICRSS data. However, to provide for a more 
extensive evaluation of Cryptosporidium indicator criteria, EPA is 
proposing that large systems measure E. coli and turbidity in their 
source water when they sample for Cryptosporidium. This was recommended 
by the Advisory Committee and will allow for possible development of 
alternative indicator levels or parameters (e.g., turbidity in 
combination with E. coli) to serve as triggers for small system 
Cryptosporidium monitoring.
Time Frame for Monitoring
    In recommending a time frame for LT2ESWTR monitoring, the Agency 
considered the trade-off between monitoring over a long period to 
better capture year-to-year fluctuations, and the desire to prescribe 
additional treatment quickly to systems identified as having high 
source water pathogen levels. Reflecting Advisory Committee 
recommendations, EPA is proposing that large systems evaluate their 
source water Cryptosporidium levels using 2 years of monitoring. This 
will account for some degree of yearly variability, without 
significantly delaying additional public health protection where 
needed.
    ii. Systems serving fewer than 10,000 people.
Indicator Monitoring
    In recognition of the relatively high cost of analyzing samples for 
Cryptosporidium, EPA and the Advisory Committee explored the use of 
indicator criteria to identify drinking water sources that may have 
high levels of Cryptosporidium occurrence. The goal was to find one or 
more parameters that could be analyzed at low cost and identify those 
systems likely to exceed the Bin 1 boundary of 0.075 oocysts/L. Data 
from the Information Collection Rule and ICRSS were evaluated for 
possible indicator parameters, including fecal coliforms, total 
coliforms, E. coli, viruses (Information Collection Rule only), and 
turbidity. Based on available data, E. coli was found to provide the 
best performance as a Cryptosporidium indicator, and the inclusion of 
other parameters like turbidity was not found to improve accuracy.
    The next part of this section presents data that support E. coli 
mean concentrations of 10/100 mL and 50/100 mL as proposed screening 
levels that will trigger Cryptosporidium monitoring in reservoir/lake 
and flowing stream systems, respectively. It describes how E. coli and 
Cryptosporidium data from the Information Collection Rule and ICRSS 
were analyzed and shows the performance of different concentrations of 
E. coli as an indicator for systems that will exceed the Bin 1 boundary 
of 0.075 oocysts/L.
    Information Collection Rule data were evaluated as maximum running 
annual averages (Information Collection Rule samples were collected 
once per month for 18 months) while ICRSS data were evaluated using an 
annual mean (ICRSS samples were collected twice per month for 12 
months). In addition, as indicators were being evaluated it became 
apparent that it was necessary to analyze plants separately based on 
source water type, due to a significantly different relationship 
between E. coli and Cryptosporidium in reservoir/lake systems compared 
to flowing stream systems.
    Analyzing the performance of an E. coli level as a screen to 
trigger Cryptosporidium monitoring under the proposed LT2ESWTR involved

[[Page 47674]]

evaluating each water treatment plant in the data set relative to two 
factors: (1) Did the plant E. coli level exceed the trigger value being 
assessed? and (2) Did the plant mean Cryptosporidium concentration 
exceed 0.075 oocysts/L? Accordingly, plants were sorted into four 
categories, based on Cryptosporidium and E. coli concentrations:
    [sbull] Plants with Cryptosporidium < 0.075 oocysts/L that did not 
exceed the E. coli trigger level (Figure IV-1, box A)
    [sbull] Plants with Cryptosporidium < 0.075 oocysts/L that exceeded 
the E. coli trigger level (Figure IV.1, box B)
    [sbull] Plants with Cryptosporidium = 0.075 oocysts/L 
that did not exceed the E. coli trigger level (Figure IV.1, box C)
    [sbull] Plants with Cryptosporidium = 0.075 oocysts/L 
that exceeded the E. coli trigger level (Figure IV.1, box D)

Summary data with E. coli trigger concentrations ranging from 5 to 100 
per 100 mL are presented for Information Collection Rule and ICRSS data 
in Figures IV-2 and IV-3.
    The performance of each E. coli level as a trigger for 
Cryptosporidium monitoring was evaluated based on false negative and 
false positive rates. False negatives occur when plants do not exceed 
the E. coli trigger value, but exceed a Cryptosporidium level of 0.075 
oocysts/L. False positives occur when plants exceed the E. coli trigger 
value but do not exceed a Cryptosporidium level of 0.075 oocysts/L. The 
false negative rate is critical because it characterizes the ability of 
the indicator to identify those plants with high Cryptosporidium 
levels. In general, low false negative rates can be achieved by 
lowering the E. coli trigger concentration. However, when the E. coli 
trigger concentration is decreased, more plants with low 
Cryptosporidium levels in their source water exceed it. As a result, 
more plants incur false positives. Consequently, identifying an 
appropriate E. coli concentration to trigger Cryptosporidium monitoring 
involves balancing false negatives and false positives to minimize 
both.
    Results of the indicator analysis for plants with flowing stream 
sources are shown in Figure IV-2. An E. coli trigger concentration of 
50/100 mL produced zero false negatives for both data sets. This means 
that in these data sets, all plants that exceeded mean Cryptosporidium 
concentrations of 0.075 oocysts/L also exceeded the E. coli trigger 
concentration and would, therefore, be required to monitor. However, 
this trigger concentration had a significant false positive rate (i.e., 
it was not highly specific in targeting only those plants with high 
Cryptosporidium levels). False positive rates were 57% (24/42) and 53% 
(9/17) with Information Collection Rule and ICRSS data, respectively. 
At a higher E. coli trigger concentration, such as 100/100 mL, the 
false negative rate increased to 12.5% (3/24) with Information 
Collection Rule data and 50% (2/4) with ICRSS data, while the false 
positive rate decreased to 43% (18/42) and 35% (6/17), respectively. 
Consequently, EPA is proposing a mean E. coli concentration of 50/100 
mL as a trigger for Cryptosporidium monitoring by small systems with 
flowing stream sources.
    Results of the indicator analysis for plants with reservoir/lake 
sources are shown in Figure IV-3. An E. coli trigger of 10/100 mL 
resulted in a false negative rate of 20% (2/10) with Information 
Collection Rule data and 67% (2/3) with ICRSS data (misclassified 2 out 
of 3 plants over 0.075 oocysts/L). Going to a lower concentration E. 
coli trigger, such as 5 per 100 mL, decreased the false negative rate 
in both the Information Collection Rule and ICRSS data sets by one 
plant, but increased the false positive rate from 20% to 43% (13/30) in 
the ICRSS data and from 24% to 39% (44/114) in the Information 
Collection Rule data. Based on these results, EPA is proposing that a 
mean E. coli concentration of 10/100 mL trigger small systems using 
lake/reservoir sources into monitoring for Cryptosporidium. While the 
false negative rate associated with this trigger value in the ICRSS 
data set is high, the ICRSS data set contains only 3 reservoir/lake 
plants that exceeded a Cryptosporidium level of 0.075 oocysts/L.
    Due to limitations in the available data, the Advisory Committee 
did not recommend that large systems use the E. coli indicator screen, 
as Cryptosporidium monitoring is less of an economic burden for large 
systems. Rather, the Advisory Committee recommended that large systems 
sample for E. coli and turbidity when they monitor for Cryptosporidium 
under the LT2ESWTR. These data will then be used to verify or, if 
necessary, further refine the proposed indicator trigger values for 
small systems. EPA concurs with these recommendations and they are 
reflected in today's proposal.
    The proposed monitoring schedule under the LT2ESWTR is set up to 
allow EPA and stakeholders to evaluate large system monitoring data for 
indicator relationships prior to the start of small system E. coli 
monitoring. After one year of large system monitoring is completed, EPA 
will begin analyzing monitoring data to assess whether alternative 
indicator strategies would be appropriate. Depending on the findings of 
this analysis, EPA may issue guidance to States on approving 
alternative indicator trigger strategies for small systems. Therefore, 
the proposed rule is written with the allowance for States to approve 
alternative indicator strategies.
BILLING CODE 6560-50-P

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BILLING CODE 6560-50-C

Cryptosporidium Monitoring

    Small systems that exceed the E. coli trigger must conduct 
Cryptosporidium monitoring, beginning 6 months after completion of E. 
coli monitoring. As recommended by the Advisory Committee, EPA is 
proposing that small systems collect 24 Cryptosporidium samples over a 
period of one year. This number of samples is the same as required for 
large systems, but the monitoring burden is targeted only on those 
plants that E. coli monitoring indicates to have elevated levels of 
fecal matter in the source water. By completing Cryptosporidium 
monitoring in one year, small systems will conduct a total of 2 years 
of monitoring to determine LT2ESWTR bin classification (including the 
one year of E. coli monitoring). This time frame is equivalent to the 
requirement for large systems, which monitor for Cryptosporidium, E. 
coli, and turbidity for 2 years.
    The Stage 2 M-DBP Agreement in Principle recommended that EPA 
explore the feasibility of alternative, lower frequency, 
Cryptosporidium monitoring criteria for providing a conservative mean 
estimate in small systems. As described earlier, EPA has evaluated 
smaller sample sizes, such as systems taking 12 or 8 samples instead of 
24 (see Table IV-6). However, EPA has concluded that these smaller 
sample sizes result in unacceptably high misclassification rates. For 
example, bin classification based on the second highest of 12 samples 
produces an estimated false positive rate of 47% for systems with a 
mean Cryptosporidium concentration 0.5 log below the Bin 1 boundary of 
0.075/L. In comparison, bin classification based on the mean of 24 
samples achieves a false positive rate of 2.8% for systems at this 
Cryptosporidium concentration. Consequently, EPA is proposing no 
alternatives to the requirement that small systems take at least 24 
samples.
    Small system bin classification will be determined by the 
arithmetic mean of the 24 samples collected over one year. Because the 
bin structure in the LT2ESWTR is based on annual mean Cryptosporidium 
levels, it is necessary that bin classification involve averaging 
samples over at least one year. Consequently, small systems will 
determine their bin classification by averaging results from all 
Cryptosporidium samples collected during their one year of monitoring.
    iii. Future monitoring and reassessment. EPA is proposing that 
beginning 6 years after the initial bin classification, large and small 
systems conduct another round of monitoring to determine if source 
water conditions have changed to a degree that may warrant a revised 
bin classification. The Advisory Committee recommended that EPA convene 
a stakeholder process within 4 years after the initial bin 
classification to develop recommendations on how best to proceed with 
implementing this second round of monitoring. Unless EPA modifies the 
LT2ESWTR to allow for an improved analytical method or a revised bin 
structure based on new risk information, the second round of monitoring 
will be conducted under the same requirements that apply to the initial 
round of monitoring.
    In addition, EPA is proposing to use the required assessment of the 
water source during sanitary surveys as an ongoing measure of whether 
significant changes in watersheds have occurred that may lead to 
increased contamination. Where the potential for increased 
contamination is identified, States must determine what follow-up 
actions by the system are necessary, including the possibility of the 
system providing additional treatment from the microbial toolbox.
    d. Basis for accepting previously collected data. Members of the 
Advisory Committee had multiple objectives in recommending that EPA 
allow the use of previously collected (grandfathered) Cryptosporidium 
data. These include (1) giving credit for data collected by proactive 
utilities, (2) facilitating early determination of LT2ESWTR compliance 
needs and, thereby, allowing for early planning of appropriate 
treatment selection, (3) increasing laboratory capacity to meet demand 
for Cryptosporidium analysis under the LT2ESWTR, and (4) allowing 
utilities to improve their data set for bin determination by 
considering more than 2 years of data (i.e., include data collected 
prior to effective date of LT2ESWTR). The latter objective incorporates 
the assumption that occurrence can vary from year to year, so that if 
more years of data are used in the bin determination, the source water 
concentration estimate will be a more accurate representation of the 
overall mean.
    A significant issue with accepting previously collected data for 
making bin determinations is ensuring that the data are of equivalent 
quality to data that will be collected following LT2ESWTR promulgation. 
As noted previously, EPA is establishing requirements so that data 
collected under the LT2ESWTR will be similar in quality to data that 
were generated under the ICRSS. These requirements include the use of 
approved analytical methods and compliance with method quality control 
(QC) criteria, use of approved laboratories, minimum sample volume, and 
a sampling schedule with minimum frequency. For example, under the 
ICRSS, laboratories analyzed 10 L samples and (considered collectively) 
achieved a mean Cryptosporidium recovery of approximately 43% in spiked 
source water with a relative standard deviation (RSD) of 50%. EPA 
anticipates that laboratories conducting Cryptosporidium analysis for 
the LT2ESWTR will collectively achieve similar analytical method 
performance. Consequently, EPA expects previously collected data sets 
used under the LT2ESWTR to meet these standards and has established 
criteria for accepting previously collected data accordingly (see 
section IV.A.1.d).
    Systems are requested, but not required, to notify EPA prior to 
promulgation of the LT2ESWTR of their intent to submit previously 
collected data. This will help EPA allocate the resources that will be 
needed to evaluate these data in order to make a decision on adequacy 
for bin determination. Systems that have at least 2 years of previously 
collected data to grandfather when the LT2ESWTR is promulgated and do 
not intend to conduct new monitoring under the rule are required to 
submit the previously collected data to EPA within 2 months following 
promulgation. This will enable EPA to evaluate the data and report back 
to the utility in sufficient time to allow, if needed, the utility to 
contract with a laboratory to conduct monitoring under the LT2ESWTR.
    Systems that have fewer than 2 years of previously collected data 
to grandfather when the LT2ESWTR is promulgated, or that intend to 
grandfather 2 or more years of previously collected data and also 
conduct new monitoring under the rule, are required to submit the 
previously collected data to EPA within 8 months following 
promulgation. This will allow these utilities to continue to collect 
previously collected data in the 6 month period between promulgation 
and the date when monitoring under the LT2ESWTR must begin, plus a 2 
month period for systems to compile the data and supporting 
documentation. Utilities may submit the data earlier than 8 months 
after promulgation if they acquire 2 years of previously collected data 
before this date.
    Submitted grandfathered data sets must include all routine source 
water monitoring results for samples collected during the time period 
covered by the

[[Page 47678]]

grandfathered data set (i.e., the time period between collection of the 
first and last samples in the data set). However, systems are not 
required under the LT2ESWTR to submit previously collected data for 
samples outside of this time period.
3. Request for Comment
    EPA requests comments on all aspects of the monitoring and 
treatment requirements proposed in this section. In addition, EPA 
requests comment on the following issues:
Requirements for Systems That Use Surface Water for Only Part of the 
Year
    Bin classification for the LT2ESWTR is based on the mean annual 
sourcewater Cryptosporidium level. Consequently, today's proposal 
requires E. coli and Cryptosporidium monitoring to be conducted over 
the full year. However, EPA recognizes that some systems use surface 
water for only part of the year. This occurs with systems that use 
surface water for part of the year (e.g., during the summer) to 
supplement ground water sources and with systems like campgrounds that 
are in operation for only part of the year. Year round monitoring for 
these systems may present both logistic and economic difficulties. EPA 
is requesting comment on how to apply LT2ESWTR monitoring requirements 
to surface water systems that operate or use surface water for only 
part of the year. Possible approaches that may be considered for 
comment include the following:
    Small public water systems that operate or use surface water for 
only part of the year could be required to collect E. coli samples at 
least bi-weekly during the period when they use surface water. If the 
mean E. coli concentration did not exceed the trigger level (e.g., 10/
100 mL for reservoirs/lakes or 50/100mL for flowing streams), systems 
could apply to the State to waive any additional E. coli monitoring. 
The State could grant the waiver, require additional E. coli 
monitoring, or require monitoring of an alternate indicator. If the 
mean E. coli concentration exceeded the trigger level, the State could 
require the system to provide additional treatment for Cryptosporidium 
consistent with Bin 4 requirements, or require monitoring of 
Cryptosporidium or an indicator, with the results potentially leading 
to additional Cryptosporidium treatment requirements.
    Large public water systems that operate or use surface water for 
only part of the year could be required to collect Cryptosporidium 
samples (along with E. coli and turbidity) either twice-per-month 
during the period when they use surface water or 12 samples per year, 
whichever is smaller. Samples would be collected during the two years 
of the required monitoring period, and bin classification would be 
based on the highest average of the two years.
    EPA requests comment on these and other approaches for both small 
and large systems.
Previously Collected Monitoring Data That Do Not Meet QC Requirements
    EPA is proposing requirements for acceptance of previously 
collected monitoring data that are equivalent to requirements for data 
generated under the LT2ESWTR. The Agency is aware that systems will 
have previously collected Cryptosporidium data that do not meet all 
sampling and analysis requirements (e.g., quality control, sample 
frequency, sample volume) proposed for data collected under the 
LT2ESWTR. However, the Agency has been unable to develop an approach 
for allowing systems to use such data for LT2ESWTR bin classification. 
This is due to uncertainty regarding the impact of deviations from 
proposed sampling and analysis requirements on data quality and 
reliability. For example, Methods 1622 and 1623 have been validated 
within the limits of the QC criteria specified in these methods. While 
very minor deviations from required QA/QC criteria may have only a 
minor impact on data quality, the Agency has not identified a basis for 
establishing alternative standards for data acceptability.
    EPA requests comment on whether or under what conditions previously 
collected data that do not meet the proposed criteria for LT2ESWTR 
monitoring data should be accepted for use in bin determination. 
Specifically, EPA requests comment on the sampling frequency 
requirement for previously collected data, and whether EPA should allow 
samples collected at lower or varying frequencies to be used as long as 
the data are representative of seasonal variation and include the 
required number of samples. If so, how should EPA determine whether 
such a data set is unbiased and representative of seasonal variation? 
How should data collected at varying frequency be averaged?
Monitoring for Systems That Recycle Filter Backwash
    Plants that recycle filter backwash water may, in effect, increase 
the concentration of Cryptosporidium in the water that enters the 
filtration treatment train. Under the LT2ESWTR proposal, microbial 
sampling may be conducted on source water prior to the addition of 
filter backwash water. EPA requests comment on how the effect of 
recycling filter backwash should be considered in LT2ESWTR monitoring.
Bin Assignment for Systems That Fail To Complete Required Monitoring
    Today's proposal classifies systems that fail to complete required 
monitoring in Bin 4, the highest treatment bin. EPA requests comment on 
alternative approaches for systems that fail to complete required 
monitoring, such as classifying the system in a bin based on data the 
system has collected, or classifying the system in a bin one level 
higher than the bin indicated by the data the system has collected. The 
shortcoming to these alternative approaches is that bin classification 
becomes more uncertain, and the likelihood of bin misclassification 
increases, as systems collect fewer than the required 24 
Cryptosporidium samples. Consequently, the proposed approach is for 
systems to collect all required samples.
    Note that under today's proposal, systems may provide 5.5 log of 
treatment for Cryptosporidium (i.e., comply with Bin 4 requirements) as 
an alternative to monitoring. Where systems notify the State that they 
will provide treatment instead of monitoring, they will not incur 
monitoring violations.
Monitoring Requirements for New Plants and Sources
    The proposed LT2ESWTR would establish calendar dates when the 
initial and second round of source water monitoring must be conducted 
to determine bin classification. EPA recognizes that new plants will 
begin operation, and that existing plants will access new sources, 
after these dates. EPA believes that new plants and plants switching 
sources should conduct monitoring equivalent to that required of 
existing plants to determine the required level of Cryptosporidium 
treatment. The monitoring could be conducted before a new plant or 
source is brought on-line, or initiated within some time period 
afterward. EPA requests comment on monitoring and treatment 
requirements for new plants and sources.
Determination of LT2ESWTR Bin Classification
    In today's proposal, EPA expects that systems will be assigned to 
LT2ESWTR risk bins based on their reported Cryptosporidium monitoring 
results and the calculations proposed for bin

[[Page 47679]]

assignment described in this section. EPA requests comment on whether 
bin classifications should formally be made or reviewed by States.
Source Water Type Classification for Systems That Use Multiple Sources
    In today's proposal, the E. coli concentrations that trigger small 
system Cryptosporidium monitoring are different for systems using lake/
reservoir and flowing stream sources. However, EPA recognizes that some 
systems use multiple sources, potentially including both lake/reservoir 
and flowing stream sources, and that the use of different sources may 
vary during the year. Further, some systems use sources that are ground 
water under the direct influence (GWUDI) of surface water. EPA requests 
comment on how to apply the E. coli criteria for triggering 
Cryptosporidium monitoring to systems using multiple sources and GWUDI 
sources.

B. Unfiltered System Treatment Technique Requirements for 
Cryptosporidium

1. What Is EPA Proposing Today?
    a. Overview. EPA is proposing treatment technique requirements for 
Cryptosporidium in unfiltered systems. Today's proposal requires all 
unfiltered systems using surface water or ground water under the direct 
influence of surface water to achieve at least 2 log (99%) inactivation 
of Cryptosporidium prior to the distribution of finished water. 
Further, unfiltered systems must monitor for Cryptosporidium in their 
source water, and where monitoring demonstrates a mean level above 0.01 
oocysts/L, systems must provide at least 3 log Cryptosporidium 
inactivation. Disinfectants that can be used to meet this treatment 
requirement include ozone, ultraviolet (UV) light, and chlorine 
dioxide.
    All current requirements for unfiltered systems under 40 CFR 141.71 
and 141.72(a) remain in effect, including requirements to inactivate at 
least 3 log of Giardia lamblia and 4 log of viruses. In addition, 
unfiltered systems must meet their overall disinfection requirements 
using a minimum of two disinfectants. These proposed requirements 
reflect recommendations of the Stage 2 M-DBP Federal Advisory 
Committee. Details of the proposed requirements are described in the 
following sections.
    b. Monitoring requirements. Requirements for Cryptosporidium 
monitoring by unfiltered systems are similar to requirements for 
filtered systems of the same size, as given in section IV.A.1. 
Unfiltered systems serving at least 10,000 people must sample their 
source water for Cryptosporidium at least monthly for two years, 
beginning no later than 6 months after promulgation of this rule. 
Samples may be collected more frequently (e.g., semi-monthly, weekly) 
as long as a consistent frequency is maintained throughout the 
monitoring period.
    Unfiltered systems serving fewer than 10,000 people must conduct 
source water sampling for Cryptosporidium at least twice-per-month for 
one year, beginning no later than 4 years following promulgation of 
this rule (i.e., on the same schedule as small filtered systems). 
However, unlike small filtered systems, small unfiltered systems cannot 
monitor for an indicator (e.g., E. coli) to determine if they are 
required to monitor for Cryptosporidium. EPA has not identified 
indicator criteria that can effectively screen for plants with 
Cryptosporidium concentrations below 0.01 oocysts/L. Consequently, all 
small unfiltered systems must conduct Cryptosporidium monitoring.
    As described in section IV.K and IV.L, Cryptosporidium analyses 
must be performed on at least 10 L per sample with EPA Methods 1622 or 
1623, and must be conducted by laboratories approved for these methods 
by EPA. Analysis of larger sample volumes is allowed, provided the 
laboratory has demonstrated comparable method performance to that 
achieved on a 10 L sample. Section IV.J describes requirements for 
reporting sample analysis results. All Cryptosporidium samples must be 
collected in accordance with a schedule that is developed by the system 
and submitted to EPA or the State at least 3 months prior to initiation 
of sampling. Refer to section IV.A.1 for requirements pertaining to any 
failure to report a valid sample analysis result for a scheduled 
sampling date and procedures for collecting a replacement sample.
    Unfiltered systems are required to participate in future 
Cryptosporidium monitoring on the same schedule as filtered systems of 
the same size. Future monitoring requirements for filtered systems are 
described in section IV.A.1.
    Unfiltered systems are not required to conduct source water 
Cryptosporidium monitoring under the LT2ESWTR if the system currently 
provides or will provide a total of at least 3 log Cryptosporidium 
inactivation, equivalent to meeting the treatment requirements for 
unfiltered systems with a mean Cryptosporidium concentration of greater 
than 0.01 oocysts/L. Systems must notify the State not later than the 
date the system is otherwise required to submit a sampling schedule for 
monitoring. Systems must install and operate technologies to provide a 
total of at least 3 log Cryptosporidium inactivation by the applicable 
date in Table IV-24.
    c. Treatment requirements. All unfiltered systems must provide 
treatment for Cryptosporidium, and the degree of required treatment 
depends on the level of Cryptosporidium in the source water as 
determined through monitoring. Unfiltered systems must calculate their 
average source water Cryptosporidium concentration using the arithmetic 
mean of all samples collected during the required two year monitoring 
period (or one year monitoring period for small systems). For 
unfiltered systems with mean source water Cryptosporidium levels of 
less than or equal to 0.01 oocysts/L, 2 log Cryptosporidium 
inactivation is required. Where the mean source water level is greater 
than 0.01 oocysts/L, 3 log inactivation is required.
    In addition, unfiltered systems are required to use at least two 
different disinfectants to meet their overall inactivation requirements 
for viruses (4 log), Giardia lamblia (3 log), and Cryptosporidium (2 or 
3 log). Further, each of the two disinfectants must achieve by itself 
the total inactivation required for one of these three pathogen types. 
For example, a system could use UV light to achieve 2 log inactivation 
of Cryptosporidium and Giardia lamblia, and use chlorine to inactivate 
1 log Giardia lamblia and 4 log viruses. In this case, chlorine would 
achieve the total inactivation required for viruses while UV light 
would achieve the total inactivation required for Cryptosporidium, and 
the two disinfectants together would meet the overall treatment 
requirements for viruses, Giardia lamblia, and Cryptosporidium. In all 
cases unfiltered systems must continue to meet disinfectant residual 
requirements for the distribution system.
    EPA has developed criteria, described in sections IV.C.14-15, for 
systems to determine Cryptosporidium inactivation credits for chlorine 
dioxide, ozone, and UV light. Unfiltered systems are allowed to use any 
of these disinfectants to meet the 2 (or 3) log Cryptosporidium 
inactivation requirement. The following paragraphs describe standards 
for demonstrating compliance with the proposed Cryptosporidium 
treatment technique requirement. For systems using ozone and chlorine 
dioxide, these standards are similar to current standards for 
compliance with Giardia

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lamblia and virus treatment requirements, as established by the SWTR in 
40 CFR 141.72 and 141.74. However, for systems using UV light, modified 
compliance standards are proposed, due to the different way in which UV 
disinfection systems will be monitored.
    Each day a system using ozone or chlorine dioxide serves water to 
the public, the system must calculate the CT value(s) from the system's 
treatment parameters, using the procedures specified in 40 CFR 
141.74(b)(3). The system must determine whether this value(s) is 
sufficient to achieve the required inactivation of Cryptosporidium 
based on the CT criteria specified in section IV.C.14. The disinfection 
treatment must ensure at least 99 percent (or 99.9 percent if required) 
inactivation of Cryptosporidium every day the system serves water to 
the public, except any one day each month. Systems are required to 
report daily CT values on a monthly basis, as described in section 
IV.J.
    Each day a system using UV light serves water to the public, the 
system must monitor for the parameters, including flow rate and UV 
intensity, that demonstrate whether the system's UV reactors are 
operating within the range of conditions that have been validated to 
achieve the required UV dose, as specified in section IV.C.15. Systems 
must monitor each UV reactor while in use and must record periods when 
any reactor operates outside of validated conditions. The disinfection 
treatment must ensure at least 99 percent (or 99.9 percent if required) 
inactivation of Cryptosporidium in at least 95 percent of the water 
delivered to the public every month. Systems are required to report 
periods when UV reactors operate outside of validated conditions on a 
monthly basis, as described in section IV.J.
    Unfiltered systems currently must comply with requirements for DBPs 
as a condition of avoiding filtration under 40 CFR 141.71(b)(6). As 
described earlier, EPA is developing a Stage 2 DBPR, which will further 
limit allowable levels of certain DBPs, specifically trihalomethanes 
and haloacetic acids. EPA intends to incorporate new standards for DBPs 
established under the Stage 2 DBPR into the criteria for filtration 
avoidance.
2. How Was This Proposal Developed?
    a. Basis for Cryptosporidium treatment requirements. The intent of 
the proposed treatment requirements for unfiltered systems is to 
achieve public health protection against Cryptosporidium equivalent to 
filtration systems. As described in section III.C, an assessment of 
survey data indicates that under current treatment requirements, 
finished water Cryptosporidium levels are higher in unfiltered systems 
than in filtered systems.
    Information Collection Rule data show an average plant-mean 
Cryptosporidium level of 0.59 oocysts/L in the source water of filtered 
plants and 0.014 oocysts/L in unfiltered systems. Median plant-mean 
concentrations were 0.052 and 0.0079 oocysts/L in filtered and 
unfiltered system sources, respectively. Thus, these results suggest 
that typical Cryptosporidium occurrence in filtered system sources is 
approximately 10 times higher than in unfiltered system sources.
    In translating these data to assess finished water risk, EPA and 
the Advisory Committee estimated that conventional plants in compliance 
with the IESWTR achieve an average Cryptosporidium removal of 3 log 
(see discussion in section III.D). Hence, if the median source water 
Cryptosporidium level at conventional plants is approximately 10 times 
higher than at unfiltered systems, and it is estimated that 
conventional plants achieve an average reduction of 3 log (99.9%), then 
the median finished water Cryptosporidium concentration at conventional 
plants is lower by a factor of 100 than at unfiltered systems. 
Therefore, to ensure equivalent public health protection, unfiltered 
systems should reduce Cryptosporidium levels by 2 log.
    Due to the development of criteria for Cryptosporidium inactivation 
with ozone, chlorine dioxide, and UV light, EPA has determined that it 
is feasible for unfiltered systems to comply with a Cryptosporidium 
treatment technique requirement. Consequently, EPA is proposing that 
all unfiltered systems provide at least 2 log inactivation of 
Cryptosporidium.
    The proposed treatment requirements for unfiltered systems with 
higher source water Cryptosporidium levels are consistent with proposed 
treatment requirements for filtered systems. As discussed previously, 
EPA is proposing that filtered plants with mean source water 
Cryptosporidium levels between 0.075 and 1.0 oocysts/L, as measured by 
Methods 1622 and 1623, provide at least a 4 log reduction (with greater 
treatment required for higher source water pathogen levels). These 
requirements will achieve average treated water Cryptosporidium 
concentrations below 1 oocyst/10,000 L in filtered systems. An 
unfiltered system with a mean source water Cryptosporidium 
concentration above 0.01 oocyst/L would need to provide more than 2 log 
inactivation in order to achieve an equivalent finished water oocyst 
level. Therefore, EPA is proposing that unfiltered systems provide at 
least 3 log inactivation where mean concentrations exceed 0.01 oocysts/
L.
    For unfiltered systems using UV disinfection to meet these proposed 
Cryptosporidium treatment requirements, EPA is proposing that 
compliance be based on a 95th percentile standard (i.e., at least 95 
percent of the water must be treated to the required UV dose). This 
standard is intended to be comparable with the ``every day except any 
one day per month'' compliance standard established by the SWTR for 
chemical disinfection (see 40 CFR 141.72(a)(1)). Because UV 
disinfection systems will typically consist of multiple parallel 
reactors that will be monitored continuously, the Agency has determined 
that it is more appropriate to base a compliance determination on the 
percentage of water disinfected to the required level, rather than a 
single daily measurement. The UV Disinfection Guidance Manual (USEPA 
2003d) will provide advice on meeting this proposed standard. A draft 
of this guidance is available in the docket for today's proposal 
(http://www.epa.gov/edocket/).
    b. Basis for requiring the use of two disinfectants. EPA is 
proposing that unfiltered systems use at least two different 
disinfectants to meet the 2 (or 3), 3, and 4 log inactivation 
requirements for Cryptosporidium, Giardia lamblia, and viruses, 
respectively. The purpose of this requirement is to provide for 
multiple barriers of protection against pathogens. One benefit of this 
approach is that if one barrier were to fail then there would still be 
one remaining barrier to provide protection against some of the 
pathogens that might be present. For example, if a plant used UV to 
inactivate Cryptosporidium and Giardia lamblia, along with chlorine to 
inactivate viruses, and the UV system were to malfunction, the chlorine 
would still meet the treatment requirement for viruses and would 
provide some degree of protection against Giardia lamblia.
    Another benefit of multiple barriers is that they will typically 
provide more effective protection against a broad spectrum of pathogens 
than a single disinfectant. Because the efficacy of disinfectants 
against different pathogens varies widely, using multiple disinfectants 
will generally provide more efficient inactivation of a wide

[[Page 47681]]

range of pathogens than a single disinfectant.
    EPA is aware, though, that this requirement would not result in a 
redundant barrier for each type of pathogen. In the example of a plant 
using chlorine and UV, the chlorine would provide essentially no 
protection against Cryptosporidium and might achieve only a small 
amount of Giardia lamblia inactivation if it was designed primarily to 
inactivate viruses. However, since the watersheds of unfiltered systems 
are required to be protected (40 CFR 141.71), the probability is low 
that high levels of Cryptosporidium or Giardia lamblia would occur 
during the time frame necessary to address a short period of treatment 
failure.
    Note the request for comment on this topic at the end of this 
section.
    c. Basis for source water monitoring requirements. Monitoring by 
unfiltered systems is necessary to identify those with mean source 
water Cryptosporidium levels above 0.01 oocysts/L. In order to allow 
for simultaneous compliance with other microbial and disinfection 
byproduct regulatory requirements, EPA is proposing that unfiltered 
systems monitor for Cryptosporidium on the same schedule as filtered 
systems of the same size. Because EPA was not able to identify 
indicator criteria, such as E. coli, that can discriminate among 
systems above and below a mean Cryptosporidium concentration of 0.01 
oocysts/L, EPA is proposing that all unfiltered systems monitor for 
Cryptosporidium.
    Consistent with requirements for filtered systems, unfiltered 
systems are required to analyze at least 24 samples of at least 10 L 
over the two year monitoring period (one year for small systems). 
However, if an unfiltered system collected and analyzed only 24 samples 
of 10 L then a total count of 3 oocysts among all samples would result 
in a source water concentration exceeding 0.01 oocysts/L. To avoid a 
relatively small number of counts determining an additional treatment 
implication, unfiltered systems may consider conducting more frequent 
sampling or analyzing larger sample volumes (e.g., 50 L). Since the 
water sources of unfiltered systems tend to have very low turbidity 
(compared to average sources in filtered systems), it is typically more 
feasible to analyze larger sample volumes in unfiltered systems. 
Filters have been approved for Cryptosporidium analysis of 50 L 
samples. Note that analysis of larger sample volumes would not reduce 
the required sampling frequency.
3. Request for Comment
    EPA solicits comment on the proposed monitoring and treatment 
technique requirements for unfiltered systems. Specifically, the Agency 
seeks comment on the following issues:
Use of Two Disinfectants
    EPA requests comment on the proposed requirement for unfiltered 
systems to use two disinfectants and for each disinfectant to meet by 
itself the inactivation requirement for at least one regulated 
pathogen. The requirement for unfiltered systems to use two 
disinfectants was recommended by the Advisory Committee because (1) 
disinfectants vary in their efficacy against different pathogens, so 
that the use of multiple disinfectants can provide more effective 
protection against a broad spectrum of pathogens, and (2) multiple 
disinfectants provide multiple barriers of protection, which can be 
more reliable than a single disinfectant.
    An alternate approach would be to allow systems to meet the 
inactivation requirements using any combination of one or more 
disinfectants that achieved the required inactivation level for all 
pathogens. This would give systems greater flexibility and could spur 
the development of new disinfection techniques that would be applicable 
to a wide range of pathogens. However, this approach might be less 
protective against unregulated pathogens. A related question is whether 
the proposed requirements for use of two disinfectants establish an 
adequate level of multiple barriers in the treatment provided by 
unfiltered systems.
Treatment Requirements for Unfiltered Systems With Higher 
Cryptosporidium Levels
    Under the proposed LT2ESWTR, a filtered system that measures a mean 
source water Cryptosporidium level of 0.075 oocysts/L or higher is 
required to provide a total of 4 log or more reduction of 
Cryptosporidium. However, if an unfiltered system, meeting the criteria 
for avoiding filtration were to measure Cryptosporidium at this level, 
it would be required to provide only 3 log treatment. Available 
occurrence data indicate that very few, if any, unfiltered systems will 
measure mean source water Cryptosporidium concentrations above 0.075 
oocysts/L. However, EPA requests comment on whether or how this 
possibility should be addressed.

C. Options for Systems To Meet Cryptosporidium Treatment Requirements

1. Microbial Toolbox Overview
    The LT2ESWTR proposal contains a list of treatment processes and 
management practices for water systems to use in meeting additional 
Cryptosporidium treatment requirements under the LT2ESWTR. This list, 
termed the microbial toolbox, was recommended by the Stage 2 M-DBP 
Advisory Committee in the Agreement in Principle. Components of the 
microbial toolbox include watershed control programs, alternative 
sources, pretreatment processes, additional filtration barriers, 
inactivation technologies, and enhanced plant performance. The intent 
of the microbial toolbox is to provide water systems with broad 
flexibility in selecting cost-effective LT2ESWTR compliance strategies. 
Moreover, the toolbox allows systems that currently provide additional 
pathogen barriers or that can demonstrate enhanced performance to 
receive additional Cryptosporidium treatment credit.
    A key feature of the microbial toolbox is that many of the 
components carry presumptive credits towards Cryptosporidium treatment 
requirements. Plants will receive these credits for toolbox components 
by demonstrating compliance with required design and implementation 
criteria, as described in the sections that follow. Treatment credit 
greater than the presumptive credit may be awarded for a toolbox 
component based on a site-specific or technology-specific demonstration 
of performance, as described in section IV.C.17.
    While the Advisory Committee made recommendations for the degree of 
presumptive treatment credit to be granted to different toolbox 
components, the Committee did not specify the design and implementation 
conditions under which the credit should be awarded. EPA has identified 
and is proposing such conditions in today's notice, based on an 
assessment of available data. For certain toolbox components, such as 
raw water storage and roughing filters, the Agency concluded that 
available data do not support the credit recommended by the Advisory 
Committee. Consequently, EPA is not proposing a presumptive credit for 
these options.
    For each microbial toolbox component, EPA is requesting comment on: 
(1) Whether available data support the proposed presumptive credits, 
including the design and implementation conditions under which

[[Page 47682]]

the credit would be awarded, (2) whether available data are consistent 
with the decision not to award presumptive credit for roughing filters 
and raw water off-stream storage, and (3) whether additional data are 
available on treatment effectiveness of toolbox components for reducing 
Cryptosporidium levels. EPA will consider modifying today's proposal 
for microbial toolbox components based on new information that may be 
provided.
    EPA particularly solicits comment on the performance of alternative 
filtration technologies that are currently being used, as well as ones 
that systems are considering for use in the future, specifically 
including bag filters, cartridge filters, and bank filtration, in 
removing Cryptosporidium. The Agency requests both laboratory and field 
data that will support a determination of the appropriate level of 
Cryptosporidium removal credit to award to these technologies. In 
addition, the Agency requests information on the applicability of these 
technologies to different source water types and treatment scenarios. 
Data submitted in response to this request for comment should include, 
where available, associated quality assurance and cost information. 
This preamble discusses bank filtration in section IV.C.6 and bag and 
cartridge filters in section IV.C.12.
    Table IV-7 summarizes presumptive credits and associated design and 
implementation criteria for microbial toolbox components. Each 
component is then described in more detail in the sections that follow. 
EPA is also developing guidance to assist systems with implementing 
toolbox components. Pertinent guidance documents include: UV 
Disinfection Guidance Manual (USEPA 2003d), Membrane Filtration 
Guidance Manual (USEPA 2003e), and Toolbox Guidance Manual (USEPA 
2003f). Each is available in draft form in the docket for today's 
proposal (http://www.epa.gov/edocket/).

   Table IV-7.--Microbial Toolbox: Proposed Options, Log Credits, and
                   Design/Implementation Criteria \1\
------------------------------------------------------------------------
                                     Proposed Cryptosporidium log credit
          Toolbox option               with design and implementation
                                                 criteria\1\
------------------------------------------------------------------------
Watershed control program.........  0.5 log credit for State-approved
                                     program comprising EPA specified
                                     elements. Does not apply to
                                     unfiltered systems.
Alternative source/Intake           No presumptive credit. Systems may
 management.                         conduct simultaneous monitoring for
                                     LT2ESWTR bin classification at
                                     alternative intake locations or
                                     under alternative intake management
                                     strategies.
Off-stream raw water storage......  No presumptive credit. Systems using
                                     off-stream storage must conduct
                                     LT2ESWTR sampling after raw water
                                     reservoir to determine bin
                                     classification.
Pre-sedimentation basin with        0.5 log credit with continuous
 coagulation.                        operation and coagulant addition;
                                     basins must achieve 0.5 log
                                     turbidity reduction based on the
                                     monthly mean of daily measurements
                                     in 11 of the 12 previous months;
                                     all flow must pass through basins.
                                     Systems using existing pre-sed
                                     basins must sample after basins to
                                     determine bin classification and
                                     are not eligible for presumptive
                                     credit.
Lime softening....................  0.5 log additional credit for two-
                                     stage softening (single-stage
                                     softening is credited as equivalent
                                     to conventional treatment).
                                     Coagulant must be present in both
                                     stages--includes metal salts,
                                     polymers, lime, or magnesium
                                     precipitation. Both stages must
                                     treat 100% of flow.
Bank filtration (as pretreatment).  0.5 log credit for 25 ft. setback;
                                     1.0 log credit for 50 ft. setback;
                                     aquifer must be unconsolidated sand
                                     containing at least 10% fines;
                                     average turbidity in wells must be
                                     < 1 NTU. Systems using existing
                                     wells followed by filtration must
                                     monitor well effluent to determine
                                     bin classification and are not
                                     eligible for presumptive credit.
Combined filter performance.......  0.5 log credit for combined filter
                                     effluent turbidity <= 0.15 NTU in
                                     95% of samples each month.
Roughing filters..................  No presumptive credit proposed.
Slow sand filters.................  2.5 log credit as a secondary
                                     filtration step; 3.0 log credit as
                                     a primary filtration process. No
                                     prior chlorination.
Second stage filtration...........  0.5 log credit for second separate
                                     filtration stage; treatment train
                                     must include coagulation prior to
                                     first filter. No presumptive credit
                                     for roughing filters.
Membranes.........................  Log credit equivalent to removal
                                     efficiency demonstrated in
                                     challenge test for device if
                                     supported by direct integrity
                                     testing.
Bag filters.......................  1 log credit with demonstration of
                                     at least 2 log removal efficiency
                                     in challenge test.
Cartridge filters.................  2 log credit with demonstration of
                                     at least 3 log removal efficiency
                                     in challenge test.
Chlorine dioxide..................  Log credit based on demonstration of
                                     log inactivation using CT table.
Ozone.............................  Log credit based on demonstration of
                                     log inactivation using CT table.
UV................................  Log credit based on demonstration of
                                     inactivation with UV dose table;
                                     reactor testing required to
                                     establish validated operating
                                     conditions.
Individual filter performance.....  1.0 log credit for demonstration of
                                     filtered water turbidity < 0.1 NTU
                                     in 95 percent of daily max values
                                     from individual filters (excluding
                                     15 min period following backwashes)
                                     and no individual filter  0.3 NTU in two consecutive
                                     measurements taken 15 minutes
                                     apart.
Demonstration of performance......  Credit awarded to unit process or
                                     treatment train based on
                                     demonstration to the State, through
                                     use of a State-approved protocol.
------------------------------------------------------------------------
\1\ Table provides summary information only; refer to following preamble
  and regulatory language for detailed requirements.

2. Watershed Control Program
    a. What is EPA proposing today? EPA is proposing a 0.5 log credit 
towards Cryptosporidium treatment requirements under the LT2ESWTR for 
filtered systems that develop a State-approved watershed control 
program designed to reduce the level of Cryptosporidium. The watershed 
control program credit can be added to the credit awarded for any other 
toolbox component. However, this credit is not available to unfiltered 
systems, as they are currently required under 40 CFR 141.171 to 
maintain a watershed control

[[Page 47683]]

program that minimizes the potential for contamination by 
Cryptosporidium as a criterion for avoiding filtration.
    There are many potential sources of Cryptosporidium in watersheds, 
including sewage discharges and non-point sources associated with 
animal feces. The feasibility, effectiveness, and sustainability of 
control measures to reduce Cryptosporidium contamination of water 
sources will be site-specific. Consequently, the proposed watershed 
control program credit centers on systems working with stakeholders in 
the watershed to develop a site-specific program, and State review and 
approval are required. In the Toolbox Guidance Manual (USEPA 2003f), 
available in draft in the docket for today's proposal, EPA provides 
information on management practices that systems may consider in 
developing their watershed control programs.
    Initial State approval of a system's watershed control program will 
be based on State review of the system's proposed watershed control 
plan and supporting documentation. The initial approval can be valid 
until the system completes the second round of Cryptosporidium 
monitoring described in section IV.A (systems begin a second round of 
monitoring six years after the initial bin assignment). During this 
period, the system is responsible for implementing the approved plan 
and complying with other general requirements, such as an annual 
watershed survey and program status report. These requirements are 
further described later in this section.
    The period during which State approval of a watershed control 
program is in effect is referred to as the approval period. Systems 
that want to continue their eligibility to receive the 0.5 log 
Cryptosporidium treatment credit must reapply for State approval of the 
program for each subsequent approval period. In general, the re-
approval will be based on the State's review of the system's 
reapplication package, as well as the annual status reports and 
watershed surveys. Subsequent approval(s) by the State of the watershed 
control program typically will be for a time equivalent to the first 
approval period, but States have the discretion to renew approval for a 
longer or shorter time period.
Requirements for Initial State Approval of Watershed Control Programs
    Systems that intend to pursue a 0.5 log Cryptosporidium treatment 
credit for a watershed control program are required to notify the State 
within one year following initial bin assignment that the system 
proposes to develop a watershed control plan and submit it for State 
approval.
    The application to the State for initial program approval must 
include the following minimum elements:
    [sbull] An analysis of the vulnerability of each source to 
Cryptosporidium. The vulnerability analysis must address the watershed 
upstream of the drinking water intake, including: A characterization of 
the watershed hydrology, identification of an ``area of influence'' 
(the area to be considered in future watershed surveys) outside of 
which there is no significant probability of Cryptosporidium or fecal 
contamination affecting the drinking water intake, identification of 
both potential and actual sources of Cryptosporidium contamination, the 
relative impact of the sources of Cryptosporidium contamination on the 
system's source water quality, and an estimate of the seasonal 
variability of such contamination.
    [sbull] An analysis of control measures that could address the 
sources of Cryptosporidium contamination identified during the 
vulnerability analysis. The analysis of control measures must address 
their relative effectiveness in reducing Cryptosporidium loading to the 
source water and their sustainability.
    [sbull] A plan that specifies goals and defines and prioritizes 
specific actions to reduce source water Cryptosporidium levels. The 
plan must explain how actions are expected to contribute to specified 
goals, identify partners and their role(s), present resource 
requirements and commitments including personnel, and include a 
schedule for plan implementation.
    The proposed watershed control plan and a request for program 
approval and 0.5 log Cryptosporidium treatment credit must be submitted 
by the system to the State no later than 24 months following initial 
bin assignment.
    The State will review the system's initial proposed watershed 
control plan and either approve, reject, or ``conditionally approve'' 
the plan. If the plan is approved, or if the system agrees to 
implementing the State's conditions for approval, the system will be 
awarded 0.5 log credit towards LT2ESWTR Cryptosporidium treatment 
requirements. A final decision on approval must be made no later than 
three years following the system's initial bin assignment.
    The initial State approval of the system's watershed control 
program can be valid until the system completes the required second 
round of Cryptosporidium monitoring. The system is responsible for 
taking the required steps, described as follows, to maintain State 
program approval and the 0.5 log credit during the approval period.
Requirements for Maintaining State Approval of Watershed Control 
Programs
    Systems that have obtained State approval of their watershed 
control program are required to meet the following ongoing requirements 
within each approval period to continue their eligibility for the 0.5 
log Cryptosporidium treatment credit:
    [sbull] Submit an annual watershed control program status report to 
the State during each year of the approval period.
    [sbull] Conduct an annual State-approved watershed survey and 
submit the survey report to the State.
    [sbull] Submit to the State an application for review and re-
approval of the watershed control program and for a continuation of the 
0.5 log treatment credit for a subsequent approval period.
    The annual watershed control program status report must describe 
the system's implementation of the approved plan and assess the 
adequacy of the plan to meet its goals. It must explain how the system 
is addressing any shortcomings in plan implementation, including those 
previously identified by the State or as the result of the watershed 
survey. If it becomes necessary during implementation to make 
substantial changes in its approved watershed control program, the 
system must notify the State and provide a rationale prior to making 
any such changes . If any change is likely to reduce the level of 
source water protection, the system must also include the actions it 
will take to mitigate the effects in its notification.
    The watershed survey must be conducted according to State 
guidelines and by persons approved by the State to conduct watershed 
surveys. The survey must encompass the area of the watershed that was 
identified in the State-approved watershed control plan as the area of 
influence and, as a minimum, assess the priority activities identified 
in the plan and identify any significant new sources of 
Cryptosporidium.
    The application to the State for review and re-approval of the 
system's watershed control program must be provided to the State at 
least six months before the current approval period expires or by a 
date previously determined by the State. The request must include a 
summary of activities and issues identified during the previous 
approval period and a revised

[[Page 47684]]

plan that addresses activities for the next approval period, including 
any new actual or potential sources of Cryptosporidium contamination 
and details of any proposed or expected changes from the existing 
State-approved program. The plan must address goals, prioritize 
specific actions to reduce source water Cryptosporidium, explain how 
actions are expected to contribute to achieving goals, identify 
partners and their role(s), resource requirements and commitments, and 
the schedule for plan implementation.
    The annual program status reports, watershed control plan and 
annual watershed sanitary surveys must be made available to the public 
upon request. These documents must be in a plain language format and 
include criteria by which to evaluate the success of the program in 
achieving plan goals. If approved by the State, the system may withhold 
portions of the annual status report, watershed control plan, and 
watershed sanitary survey based on security considerations.
    b. How was this proposal developed? The M-DBP Advisory Committee 
recommended that systems be awarded 0.5 log Cryptosporidium treatment 
credit for implementing a watershed control program. This 
recommendation was based on the Committee's recognition that some 
systems will be able to reduce the level of Cryptosporidium in their 
source water by implementing a well-designed and focused watershed 
control program. Moreover, the control measures used in the watershed 
to reduce levels of Cryptosporidium are likely to reduce concentrations 
of other pathogens as well.
    EPA concurs that well designed watershed control programs that 
focus on reducing levels of Cryptosporidium contamination of water 
sources should be encouraged, and that implementation of such programs 
will likely reduce overall microbial risk. A broad reduction in 
microbial risk will occur through the application of control measures 
and best management practices that are effective in reducing fecal 
contamination in the watershed. In addition, plant management practices 
may be enhanced by the knowledge systems acquire regarding the 
watershed and factors that affect microbial risk, such as sources, 
fate, and transport of pathogens.
    Given the highly site-specific nature of a watershed control 
program, including the feasibility and effectiveness of different 
control measures, EPA believes that systems should demonstrate their 
eligibility for 0.5 log Cryptosporidium treatment credit by developing 
targeted programs that account for site-specific factors. As part of 
developing a watershed control program, systems will be required to 
assess a number of these factors, including watershed hydrology, 
sources of Cryptosporidium in the watershed, human impacts, and fate 
and transport of Cryptosporidium. Furthermore, EPA believes that the 
State is well positioned to judge whether a system's watershed control 
program is likely to achieve a substantial reduction of Cryptosporidium 
in source water. Consequently, EPA is proposing that approval of 
watershed control programs and allowance for an associated 0.5 log 
treatment credit be made by the State on a system specific basis.
    A watershed control program could include measures such as (1) the 
elimination, reduction, or treatment of wastewater or storm water 
discharges, (2) treatment of Cryptosporidium contamination at the sites 
of waste generation or storage, (3) prevention of Cryptosporidium 
migration from sources, or (4) any other measures that are effective, 
sustainable, and likely to reduce Cryptosporidium contamination of 
source water. EPA recognizes that many public water systems do not 
directly control the watersheds of their sources of supply. EPA expects 
that systems will need to develop and maintain partnerships with 
landowners within watersheds, as well as with State governments and 
regional agencies that have authority over activities in the watershed 
that may contribute Cryptosporidium to the water supply. Stakeholders 
that have some level of control over activities that could contribute 
to Cryptosporidium contamination include municipal government and 
private operators of wastewater treatment plants, livestock farmers and 
persons who spread manure, individuals with failing septic systems, 
logging operations, and other government and commercial organizations.
    EPA has initiated a number of programs that address watershed 
management and source water protection. In 2002, EPA launched the 
Watershed Initiative (67 FR 36172, May 23, 2002) (USEPA 2002b), which 
will provide grants to support innovative watershed based approaches to 
preventing, reducing, and eliminating water pollution. In addition, EPA 
has recently promulgated new regulations for Concentrated Animal 
Feeding Operations (CAFOs), which through the NPDES permit process will 
limit discharges that contribute microbial pathogens to watersheds.
    SDWA section 1453 requires States to carry out a source water 
quality assessment program for the protection and benefit of public 
water systems. EPA issued program guidance in August of 1997, and 
expects that most States will complete their source water assessments 
of surface water systems by the end of 2003. These assessments will 
establish a foundation for watershed vulnerability analyses by 
providing the preliminary analyses of watershed hydrology, a starting 
point for defining the area of influence, and an inventory and 
hierarchy of actual and potential contamination sources. In some cases, 
these portions of the source water assessment may fully satisfy those 
analytical needs.
    As noted earlier, EPA has published and is continuing to develop 
guidance material that addresses contamination by Cryptosporidium and 
other pathogens from both non-point sources (e.g., agricultural and 
urban runoff, septic tanks) and point sources (e.g., sewer overflows, 
POTWs, CAFOs). The Toolbox Guidance Manual, available in draft with 
today's proposal, includes a list of programmatic resources and 
guidance available to assist systems in building partnerships and 
implementing watershed protection activities. In addition, this 
guidance manual incorporates available information on the effectiveness 
of different control measures to reduce Cryptosporidium levels and 
provides case studies of watershed control programs. This guidance is 
intended to assist water systems in developing their watershed control 
programs and States in their assessment and approval of these programs.
    In addition to guidance documents, demonstration projects, and 
technical resources, EPA provides funding for watershed and source 
water protection through the Drinking Water State Revolving Fund 
(DWSRF) and Clean Water State Revolving Fund (CWSRF). Under the DWSRF 
program, States may provide funding directly to public water systems 
for source water protection, including watershed management and 
pathogen source reduction plans. CWSRF funds have been used to develop 
and implement agricultural best management practices for reducing 
pathogen loading to receiving waters and to fund directly, or provide 
incentives for, the replacement of failing septic systems. EPA 
encourages the use of CWSRF for source protection and has developed 
guidelines for the award of funds to address non-point sources of 
pollution (CWA section 319 Non Point Source Pollution Program). 
Further, the Agency is promoting the broader use of

[[Page 47685]]

SRF funds to implement measures to prevent and control non-point source 
pollution. Detailed sanitary surveys, with a specific analysis of 
sources of Cryptosporidium in the watershed, will facilitate the 
process of targeting funding available under SRF programs to eliminate 
or mitigate these sources.
    c. Request for comment. EPA requests comment on the proposed 
watershed control program credit and associated program components.
    [sbull] Should the State be allowed to reduce the frequency of the 
annual watershed survey requirement for certain systems if systems 
engage in alternative activities like public outreach?
    [sbull] The effectiveness of a watershed control program may be 
difficult to assess because of uncertainty in the efficacy of control 
measures under site-specific conditions. In order to provide 
constructive guidance, EPA welcomes reports on scientific case studies 
and research that evaluated methods for reducing Cryptosporidium 
contamination of source waters.
    [sbull] Are there confidential business information (CBI) concerns 
associated with making information on the watershed control program 
available to the public? If so, what are these concerns and how should 
they be addressed?
    [sbull] How should the ``area of influence'' (the area to be 
considered in future watershed surveys) be delineated, considering the 
persistence of Cryptosporidium?
3. Alternative Source
    a. What is EPA proposing today? Plant intake refers to the works or 
structures at the head of a conduit through which water is diverted 
from a source (e.g., river or lake) into the treatment plant. Plants 
may be able to reduce influent Cryptosporidium levels by changing the 
intake placement (either within the same source or to an alternate 
source) or managing the timing or level of withdrawal.
    Because the effect of changing the location or operation of a plant 
intake on influent Cryptosporidium levels will be site specific, EPA is 
not proposing any presumptive credit for this option. Rather, if a 
system is concerned that Cryptosporidium levels associated with the 
current plant intake location and/or operation will result in a bin 
assignment requiring additional treatment under the LT2ESWTR, the 
system may conduct concurrent Cryptosporidium monitoring reflecting a 
different intake location or different intake management strategy. The 
State will then make a determination as to whether the plant may be 
classified in an LT2ESWTR bin using the alternative intake location or 
management monitoring results.
    Thus, systems that intend to be classified in an LT2ESWTR bin based 
on a different intake location or management strategy must conduct 
concurrent Cryptosporidium monitoring. The system is still required to 
monitor its current plant intake in addition to any alternative intake 
location/management monitoring, and must submit the results of all 
monitoring to the State. In addition, the system must provide the State 
with supporting information documenting the conditions under which the 
alternative intake location/management samples were collected. The 
concurrent monitoring must conform to the sample frequency, sample 
volume, analytical method, and other requirements that apply to the 
system for Cryptosporidium monitoring as stated in Section IV.A.1.
    If a plant's LT2ESWTR bin classification is based on monitoring 
results reflecting a different intake location or management strategy, 
the system must relocate the intake or implement the intake management 
strategy within the compliance time frame for the LT2ESWTR, as 
specified in section IV.F.
    b. How was this proposal developed? In the Stage 2 M-DBP Agreement 
in Principle, the Advisory Committee identified several actions related 
to the intake which potentially could reduce the concentration of 
Cryptosporidium entering a treatment plant. These actions were included 
in the microbial toolbox under the heading Alternative Source, and 
include: (1) Intake relocation, (2) change to alternative source of 
supply, (3) management of intake to reduce capture of oocysts in source 
water, (4) managing timing of withdrawal, and (5) managing level of 
withdrawal in water column.
    It is difficult to predict in advance the efficacy of any of these 
activities in reducing levels of Cryptosporidium entering the treatment 
plant. However, if a system relocates the plant intake or implements a 
different intake management strategy, it is appropriate for the plant 
to be assigned to an LT2ESWTR bin using monitoring results reflecting 
the new intake strategy.
    EPA believes that the requirements specified for monitoring to 
determine bin placement are necessary to characterize a plant's mean 
source water Cryptosporidium level. Consequently, any concurrent 
monitoring carried out to characterize a different intake location or 
management strategy should be equivalent. For this reason, the sampling 
and analysis requirements which apply to the current intake monitoring 
also apply to any concurrent monitoring used to characterize a new 
intake location or management strategy.
    EPA also recognizes that if plant's bin assignment is based on a 
new intake operation strategy then it is important for the plant to 
continue to use this new strategy in routine operation. Therefore, EPA 
is proposing that the system document the new intake operation strategy 
when submitting additional monitoring results to the State and that the 
State approve that new strategy.
    c. Request for comment. EPA requests comment on the following 
issues:
    [sbull] What are intake management strategies by which systems 
could reduce levels of Cryptosporidium in the plant influent?
    [sbull] Can representative Cryptosporidium monitoring to 
demonstrate a reduction in oocyst levels be accomplished prior to 
implementation of a new intake strategy (e.g., monitoring a new source 
prior to constructing a new intake structure)?
    [sbull] How should this option be applied to plants that use 
multiple sources which enter a plant through a common conduit, or which 
use separate sources which enter the plant at different points?
4. Off-Stream Raw Water Storage
    a. What is EPA proposing today? Off-stream raw water storage 
reservoirs are basins located between a water source (typically a 
river) and the coagulation and filtration processes in a treatment 
plant. EPA is not proposing presumptive treatment credit for 
Cryptosporidium removal through off-stream raw water storage. Systems 
using off-stream raw water storage must conduct Cryptosporidium 
monitoring after the reservoir for the purpose of determining LT2ESWTR 
bin placement. This will allow reductions in Cryptosporidium levels 
that occur through settling during off-stream storage to be reflected 
in the monitoring results and consequent LT2ESWTR bin assignment.
    The use of off-stream raw water storage reservoirs during LT2ESWTR 
monitoring must be consistent with routine plant operation and must be 
recorded by the system. Guidance on monitoring locations is provided in 
Public Water System Guidance Manual for Source Water Monitoring under 
the LT2ESWTR (USEPA 2003g), which is available in draft in the docket 
for today's proposal.
    b. How was this proposal developed? The Stage 2 M-DBP Agreement in 
Principle recommends a 0.5 log credit for off-stream raw water storage

[[Page 47686]]

reservoirs with detention times on the order of days and 1.0 log credit 
for reservoirs with detention times on the order of weeks. After a 
review of the available literature, EPA is unable to determine criteria 
that provide reasonable assurance of achieving a 0.5 or 1 log removal 
of oocysts. Consequently, EPA is not proposing a presumptive treatment 
credit for this process.
    This proposal for off-stream raw water storage represents a change 
from the November 2001 pre-proposal draft of the LT2ESWTR (USEPA 
2001g), which described 0.5 log and 1 log presumptive credits for 
reservoirs with hydraulic detention times of 21 and 60 days, 
respectively. These criteria were based on a preliminary assessment of 
reported studies, described later in this section, that evaluated 
Cryptosporidium and Giardia removal in raw water storage reservoirs.
    Subsequent to the November 2001 pre-proposal draft, the Science 
Advisory Board (SAB) reviewed the data that EPA had acquired to support 
Cryptosporidium treatment credits for off-stream raw water storage (see 
section VII.K). In written comments from a December 2001 meeting of the 
SAB Drinking Water Committee, the panel concluded that the available 
data were not adequate to demonstrate the treatment credits for off-
stream raw water storage described in the pre-proposal draft, and 
recommended that no presumptive credits be given for this toolbox 
option. The panel did agree, though, that a utility should be able to 
take advantage of off-stream raw water storage by sampling after the 
reservoir for appropriate bin placement. EPA concurs with this finding 
by the SAB and today's proposal is consistent with their 
recommendation.
    Off-stream raw water storage can improve the microbial quality of 
water in a number of ways. These include (1) reduced microbial and 
particulate loading to the plant due to settling in the reservoir, (2) 
reduced viability of pathogens due to die-off, and (3) dampening of 
water quality and hydraulic spikes. EPA has evaluated a number of 
studies that investigated the removal of Cryptosporidium and other 
microorganisms and particles in raw water storage basins. These studies 
are summarized in the following paragraphs, and selected results are 
presented in Table IV-8.

          Table IV-8.--Studies of Cryptosporidium and Giardia Removal From Off-Stream Raw Water Storage
----------------------------------------------------------------------------------------------------------------
           Researcher                  Reservoir                   Residence time               Log reductions
----------------------------------------------------------------------------------------------------------------
Ketelaars et al. 1995...........  Biesbosch reservoir  24 weeks (average)...................  Cryptosporidium-
                                   system: man-made                                            1.4 Giardia-2.3.
                                   pumped storage
                                   (Netherlands).
Van Breeman et al. 1998.........  Biesbosch reservoir  24 weeks (average)...................  Cryptosporidium-
                                   system: man-made                                            2.0 Giardia-2.6.
                                   pumped storage
                                   (Netherlands).
                                  PWN (Netherlands)..  10 weeks (average)...................  Cryptosporidium-
                                                                                               1.3 Giardia-0.8.
Bertolucci et al. 1998..........  Abandoned gravel     18 days (theoretical)................  Cryptosporidium-
                                   quarry used for                                             1.0 Giardia-0.8.
                                   storage (Italy).
Ongerth, 1989...................  Three impoundments   40, 100 and 200 days (respectively)..  No Giardia removal
                                   on rivers with                                              observed.
                                   limited public
                                   access (Seattle,
                                   WA).
----------------------------------------------------------------------------------------------------------------

    Ketelaars et al. (1995) evaluated Cryptosporidium and Giardia 
removal across a series of three man-made pumped reservoirs, named the 
Biesbosch reservoirs, with reported hydraulic retention times of 11, 9, 
and 4 weeks (combined retention time of 24 weeks). To prevent algal 
growth and hypolimnetic deoxygenation, the reservoirs were destratified 
by air-injection. Based on weekly sampling over one year, mean influent 
and effluent concentrations of Cryptosporidium were 0.10 and 0.004 
oocysts/100 L, respectively, indicating an average removal across the 
three reservoirs of 1.4 log. Mean removal of Giardia was 2.3 log.
    Van Breemen et al. (1998) continued the efforts of Ketelaars et al. 
(1995) in evaluating pathogen removal across the Biesbosch reservoir 
system. Using a more sensitive analytical method, Van Breeman et al. 
measured mean Cryptosporidium levels of 6.3 and 0.064 oocysts/100 L at 
the inlet and outlet, respectively, indicating an average removal of 
2.0 log. For Giardia, the average reduction was 2.6 log. In addition, 
Van Breeman et al. (1998) evaluated removal of Cryptosporidium, 
Giardia, and other microorganisms in a reservoir designated PWN, which 
had a hydraulic retention time of 10 weeks. Passage through this 
storage reservoir was reported to reduce the mean concentration of 
Cryptosporidium by 1.3 log and of Giardia by 0.8 log.
    Bertolucci et al. (1998) investigated removal of Cryptosporidium, 
Giardia, and nematodes in a reservoir derived from an abandoned gravel 
quarry with a detention time reported as around 18 days. Over a 2 year 
period, average influent and effluent concentrations of Cryptosporidium 
were 70 and 7 oocysts/100 L, respectively, demonstrating a mean 
reduction of 1 log. Average Giardia levels decreased from 137 cysts/
100L in the inlet to 46 cysts/100L at the outlet, resulting in a mean 
0.5 log removal.
    Ongerth (1989) studied concentrations of Giardia cysts in the Tolt, 
Cedar, and Green rivers, which drain the western slope of the Cascade 
Mountains in Washington. The watersheds of each river are controlled by 
municipal water departments for public water supply, and public access 
is limited. The Cedar, Green, and Tolt rivers each have impoundments 
with reported residence times of 100, 30-50, and 200 days, 
respectively, in the reach studied. Ongerth found no statistically 
significant difference in cyst concentrations above and below any of 
the reservoirs. Median cyst concentrations above and below the Cedar, 
Green, and Tolt reservoirs were reported as 0.12 and 0.22, 0.27 and 
0.32, and 0.16 and 0.21 cysts/L, respectively. It is unclear why no 
decrease in cyst levels was observed. It is possible that contamination 
of the water in the impoundments by Giardia from animal sources, either 
directly or through run-off, may have occurred.
    EPA has also considered results from studies which evaluated the 
rate at which Cryptosporidium oocysts lose viability and infectivity 
over time. Two studies are summarized next, with selected results 
presented in Table IV-9.

[[Page 47687]]



Table IV-9.--Studies of Cryptosporidium Die-Off During Raw Water Storage
------------------------------------------------------------------------
         Researcher            Type of experiment       Log reduction
------------------------------------------------------------------------
Medema et al. 1997..........  River water was       0.5 log reduction
                               inoculated with       over 50 days at 5
                               Cryptosporidium and   [deg]C; 0.5 log
                               bacteria and          reduction over 20-
                               incubated.            80 days at 15
                                                     [deg]C.
Sattar et al. 1999..........  Synthetic hard water  In vitro conditions
                               and natural water     showed 0.7 to 2.0
                               from several rivers   log reduction over
                               inoculated with       30 days at 20
                               Giardia and           [deg]C. Little
                               Cryptosporidium.      reduction at 4
                                                     [deg]C. In situ
                                                     conditions showed
                                                     0.4 to 1.5 log
                                                     reduction at 21
                                                     days.
------------------------------------------------------------------------

    Medema et al. (1997) conducted bench scale studies of the influence 
of temperature and the presence of biological activity on the die-off 
rate of Cryptosporidium oocysts. Die-off rates were determined at 
5[deg]C and 15[deg]C, and in both natural and sterilized (autoclaved) 
river water. Both excystation and vital dye staining were used to 
determine oocyst viability. At 5[deg]C, the die-off rate under all 
conditions was 0.010 log10/day, assuming first-order 
kinetics. This translates to 0.5 log reduction at 50 days. At 15[deg]C, 
the die-off rate in natural river water approximately doubled to 0.024 
log10/day (excystation) and 0.018 log10/day (dye 
staining). However, in autoclaved water at 15[deg]C, the die-off rate 
was only 0.006 log10/day (excystation) and 0.011 
log10/day (dye staining). These results suggest that oocyst 
die-off is more rapid at higher temperatures in natural water, and this 
behavior may be caused by increased biological or biochemical activity.
    Sattar et al. (1999) evaluated factors impacting Cryptosporidium 
and Giardia survival. Microtubes containing untreated water from the 
Grand and St. Lawrence rivers (Ontario) were inoculated with purified 
oocysts and cysts. Samples were incubated at temperatures ranging from 
4[deg]C to 30[deg]C, viability of oocysts and cysts was measured by 
excystation. At 20[deg]C and 30[deg]C, reductions in viable 
Cryptosporidium oocysts ranged from approximately 0.6 to 2.0 log after 
30 days. However, relatively little inactivation took place when 
oocysts were incubated at 4[deg]C (as low as 0.2 log at 100 days).
    To evaluate oocyst survival under dynamic environmental conditions, 
Sattar et al. seeded dialysis cassettes with Cryptosporidium oocysts 
and placed them in overflow tanks receiving water from different rivers 
in Canada and the United States. Reductions in the concentration of 
viable oocysts ranged from approximately 0.4 to 1.5 log after 21 days. 
Survival of oocysts was enhanced by pre-filtering the water, suggesting 
that microbial antagonism was involved in the natural inactivation of 
the parasites.
    Overall these studies indicate that off-stream storage of raw water 
has the potential to effect significant reductions in the concentration 
of viable Cryptosporidium oocysts, both through sedimentation and 
degradation of oocysts (i.e., die-off). However, these data also 
illustrate the challenge in reliably estimating the amount of removal 
that will occur in any particular storage reservoir. Removal and die-
off rates reported in these studies varied widely, and were observed to 
be influenced by factors like temperature, contamination, hydraulic 
short circuiting, and biological activity (Van Breeman et al. 1998, 
Medema et al. 1997, Sattar et al. 1999). Because of this variability 
and the relatively small amount of available data, it is difficult to 
extrapolate from these studies to develop nationally applicable 
criteria for awarding removal credits to raw water storage.
    c. Request for comment. EPA requests comment on the finding that 
the available data are not adequate to support a presumptive 
Cryptosporidium treatment credit for off-stream raw water storage, and 
that systems using off-stream storage should conduct LT2ESWTR 
monitoring at the reservoir outlet. This monitoring approach would 
account for reductions in oocyst concentrations due to settling, but 
would not provide credit for die-off, since non-viable oocysts could 
still be counted during monitoring. In addition, EPA would also 
appreciate comment on the following specific issues:
    [sbull] Is additional information available that either supports or 
suggests modifications to this proposal concerning off-stream raw water 
storage?
    [sbull] How should a system address the concern that water in off-
stream raw water storage reservoirs may become contaminated through 
processes like algal growth, run-off, roosting birds, and activities on 
the watershed?
5. Pre-Sedimentation With Coagulant
    a. What is EPA proposing today? Presedimentation is a preliminary 
treatment process used to remove particulate material from the source 
water before the water enters primary sedimentation and filtration 
processes in a treatment plant. EPA is proposing to award a presumptive 
0.5 log Cryptosporidium treatment credit for presedimentation that is 
installed after LT2ESWTR monitoring and meets the following three 
criteria:
    (1) The presedimentation basin must be in continuous operation and 
must treat all of the flow reaching the treatment plant.
    (2) The system must continuously add a coagulant to the 
presedimentation basin.
    (3) The system must demonstrate on a monthly basis at least 0.5 log 
reduction of influent turbidity through the presedimentation process in 
at least 11 of the 12 previous consecutive months. This monthly 
demonstration of turbidity reduction must be based on the arithmetic 
mean of at least daily turbidity measurements in the presedimentation 
basin influent and effluent, and must be calculated as follows:

Monthly mean turbidity log reduction = log10(monthly mean of 
daily influent turbidity)-log10(monthly mean of daily 
effluent turbidity).

If the presedimentation process has not been in operation for 12 
months, the system must verify on a monthly basis at least 0.5 log 
reduction of influent turbidity through the presedimentation process, 
calculated as specified in this paragraph, for at least all but any one 
of the months of operation.
    Systems with presedimentation in place at the time they begin 
LT2ESWTR Cryptosporidium monitoring are not eligible for the 0.5 log 
presumptive credit and must sample after the basin when in use for the 
purpose of determining their bin assignment. The use of 
presedimentation during LT2ESWTR monitoring must be consistent with 
routine plant operation and must be recorded by the system. Guidance on 
monitoring is provided in Public Water System Guidance Manual for 
Source Water Monitoring under the LT2ESWTR (USEPA 2003g), which is 
available in draft in the docket for today's proposal.
    b. How was this proposal developed? Presedimentation is used to 
remove gravel, sand, and other gritty material

[[Page 47688]]

from the raw water and dampen particle loading to the rest of the 
treatment plant. Presedimentation is similar to conventional 
sedimentation, except that presedimentation may be operated at higher 
loading rates and may not involve use of chemical coagulants. Also, 
some systems operate the presedimentation process periodically and only 
in response to periods of high particle loading.
    Because presedimentation reduces particle concentrations, it is 
expected to reduce Cryptosporidium levels. In addition, by dampening 
variability in source water quality, presedimentation may improve the 
performance of subsequent treatment processes. In general, the efficacy 
of presedimentation in lowering particle levels is influenced by a 
number of water quality and treatment parameters including surface 
loading rate, temperature, particle concentration, coagulation, and 
characteristics of the sedimentation basin.
    The Stage 2-M-DBP Agreement in Principle recommends 0.5 log 
presumptive Cryptosporidium treatment credit for presedimentation with 
the use of coagulant. Today's proposal is consistent with this 
recommendation. However, the proposed requirement for demonstrated 
turbidity reduction as a condition for presedimentation credit 
represents a change from the November 2001 pre-proposal draft of the 
LT2ESWTR (USEPA 2001g). Rather than a requirement for turbidity 
removal, the 2001 pre-proposal draft included criteria for maximum 
overflow rate and minimum influent turbidity as conditions for the 0.5 
log presedimentation credit.
    The Science Advisory Board (SAB) reviewed the criteria and 
supporting information for presedimentation credit in the November 2001 
pre-proposal draft (see section VII.K). In written comments from a 
December 2001 meeting of the SAB Drinking Water Committee, the panel 
concluded that available data were minimal to support a 0.5 log 
presumptive credit and recommended that no credit be given for 
presedimentation. Additionally, the panel stated that performance 
criteria other than overflow rate need to be included if credit is to 
be given for presedimentation.
    Due to this finding by the SAB, EPA further reviewed data on 
removal of aerobic spores (as an indicator of Cryptosporidium removal) 
and turbidity in full-scale presedimentation basins. As shown later in 
this section, these data indicate that presedimentation basins 
achieving a monthly mean reduction in turbidity of at least 0.5 log 
have a high likelihood of reducing mean Cryptosporidium levels by 0.5 
log or more. Consequently, EPA has determined that it is appropriate to 
use turbidity reduction as a performance criterion for awarding 
Cryptosporidium treatment credit to presedimentation basins. The Agency 
believes this performance criterion addresses the concerns raised by 
the SAB.
    The Agency has concluded that it is appropriate to limit 
eligibility for the 0.5 log presumptive Cryptosporidium treatment 
credit to systems that install presedimentation after LT2ESWTR 
monitoring. Systems with presedimentation in place prior to initiation 
of LT2ESWTR Cryptosporidium monitoring may sample after the 
presedimentation basin to determine their bin assignment. In this case, 
the effect of presedimentation in reducing Cryptosporidium levels will 
be reflected in the monitoring results and bin assignment. Systems that 
monitor after presedimentation are not subject to the operational and 
performance requirements associated with the 0.5 log credit. The SAB 
agreed that a system should be able to sample after the 
presedimentation treatment process for appropriate bin placement.
    In considering criteria for awarding Cryptosporidium removal credit 
to presedimentation, EPA has evaluated both published studies and data 
submitted by water systems using presedimentation. There is relatively 
little published data on the removal of Cryptosporidium by 
presedimentation. Consequently, EPA has reviewed studies that 
investigated Cryptosporidium removal by conventional sedimentation 
basins. These studies are informative regarding potential levels of 
performance, the influence of water quality parameters, and correlation 
of Cryptosporidium removal with removal of potential surrogates. 
However, removal efficiency in conventional sedimentation basins may be 
greater than in presedimentation due to lower surface loading rates, 
higher coagulant doses, and other factors. To supplement these studies, 
EPA has evaluated data provided by utilities on removal of other types 
of particles, primarily aerobic spores, in the presedimentation 
processes of full scale plants. Data indicate that aerobic spores may 
serve as a surrogate for Cryptosporidium removal by sedimentation 
(Dugan et al. 2001).
    i. Published studies of Cryptosporidium removal by conventional 
sedimentation basins. Table IV-10 summarizes results from published 
studies of Cryptosporidium removal by conventional sedimentation 
basins.

   Table IV-10.--Summary of Published Studies of Cryptosporidium Removal by Conventional Sedimentation Basins
----------------------------------------------------------------------------------------------------------------
              Author(s)                   Plant/process type        Cryptosporidium removal by sedimentation
----------------------------------------------------------------------------------------------------------------
Dugan et al. (2001)..................  Pilot scale              0.6 to 1.6 log (average 1.3 log).
                                        conventional.
States et al. (1997).................  Full scale conventional  0.41 log.
                                        with primary and
                                        secondary
                                        sedimentation.
Edzwald and Kelly (1998).............  Bench scale              0.8 to 1.2 log.
                                        sedimentation.
Payment and Franco (1993)............  Full scale conventional  3.8 log and 0.7 log.
                                        (2 plants).
Kelly et al. (1995)..................  Full scale conventional  0.8 log.
                                        (two stage lime
                                        softening).
                                       Full scale conventional  0.5 log.
                                        (two stage
                                        sedimentation).
Patania et al. (1995)................  Pilot scale              2.0 log (median).
                                        conventional (3
                                        plants).
----------------------------------------------------------------------------------------------------------------

    Dugan et al. (2001) evaluated the ability of conventional treatment 
to control Cryptosporidium under different water quality and treatment 
conditions on a small pilot scale plant that had been demonstrated to 
provide equivalent performance to a larger plant. Under optimal 
coagulation conditions, oocyst removal across the sedimentation basin 
ranged from 0.6 to 1.6 log, averaging 1.3 log. Suboptimal coagulation 
conditions (underdosed relative to jar test predictions) significantly 
reduced plant performance with oocyst removal in the

[[Page 47689]]

sedimentation basin averaging 0.20 log. Removal of aerobic spores, 
total particle counts, and turbidity all correlated well with removal 
of Cryptosporidium by sedimentation.
    States et al. (1997) monitored Cryptosporidium removal at the 
Pittsburgh Drinking Water Treatment Plant (65-70 million gallons per 
day (MGD)). The clarification process included ferric chloride 
coagulation, flocculation, and settling in both a small primary basin 
and a 120 MG secondary sedimentation basin. Geometric mean 
Cryptosporidium levels in the raw and settled water were 31 and 12 
oocysts/100 L, respectively, indicating a mean reduction of 0.41 log.
    Edzwald and Kelly (1998) conducted a bench-scale study to determine 
the optimal coagulation conditions with different coagulants for 
removing Cryptosporidium oocysts from spiked raw waters. Under optimal 
coagulation conditions, the authors observed oocysts reductions through 
sedimentation ranging from 0.8 to 1.2 log.
    Payment and Franco (1993) measured Cryptosporidium and other 
microorganisms in raw, settled, and filtered water samples from 
drinking water treatment plants in the Montreal area. The geometric 
mean of raw and settled water Cryptosporidium levels in one plant were 
742 and 0.12 oocysts/100 L, respectively, suggesting a mean removal of 
3.8 log. In a second plant, mean removal by sedimentation was reported 
as 0.7 log, with raw and settled water Cryptosporidium levels reported 
as <2 and <0.2 oocysts/L, respectively.
    Kelley et al. (1995) monitored Cryptosporidium levels in the raw, 
settled, and filtered water of two water treatment plants (designated 
site A and B). Both plants included two-stage sedimentation. At site A, 
mean raw and settled water Cryptosporidium levels were 60 and 9.5 
oocysts/100 L, respectively, suggesting a mean removal of 0.8 log by 
sedimentation. At site B, mean raw and settled water Cryptosporidium 
levels were 53 and 16 oocysts/100 L, respectively, for an average 
removal by sedimentation of 0.5 log. Well water was intermittently 
blended in the second stage of sedimentation at site B, which may have 
reduced settled and filtered water pathogen levels.
    Patania et al. (1995) evaluated removal of Cryptosporidium in four 
pilot scale plants. Three of these were conventional and one used in-
line filtration (rapid mix followed by filtration). Cryptosporidium 
removal was generally 1.4 to 1.8 log higher in the process trains with 
sedimentation compared to in-line filtration. While the effectiveness 
of sedimentation for organism removal varied widely under the 
conditions tested, the median removal of Cryptosporidium by 
sedimentation was approximately 2.0 log.
    ii. Data supplied by utilities on the removal of spores by 
presedimentation. Data on the removal of Cryptosporidium and spores 
(Bacillus subtilis and total aerobic spores) during operation of full-
scale presedimentation basins were collected independently and reported 
by three utilities: St. Louis, MO, Kansas City, MO, and Cincinnati, OH. 
Cryptosporidium oocysts were not detected in raw water at these 
locations at levels sufficient to calculate log removals of oocysts 
directly. However, aerobic spores were present in the raw water of 
these utilities at high enough concentrations to measure log removals 
through presedimentation as a surrogate for Cryptosporidium removal. As 
noted earlier, data from Dugan et al. (2001) demonstrate a correlation 
between removal of aerobic spores and Cryptosporidium through 
sedimentation under optimal coagulation conditions. A summary of the 
spore removal data supplied by the these utilities is shown in Table 
IV-11.

 Table IV-11.--Mean Spore Removal for Full-scale Presedimentation Basins
                       Reported by Three Utilities
------------------------------------------------------------------------
             Reporting utility                   Mean spore removal
------------------------------------------------------------------------
St. Louis Water Division..................  1.1 log (B. subtilis).
Kansas City Water Services Department.....  0.8 log (B. subtilis) (with
                                             coagulant).
                                            0.46 log (B. subtilis)
                                             (without coagulant).
Cincinnati Water Works....................  0.6 log (total aerobic
                                             spores).
------------------------------------------------------------------------

    The St. Louis Water Division operates four presedimentation basins 
at one facility. Coagulant addition prior to presedimentation includes 
polymer and occasional dosages of ferric sulfate. Bacillus subtilis 
spore samples were collected from June 1998 to September 2000. Reported 
mean spore concentrations in the raw water and following 
presedimentation were 108,326 and 8,132 cfu/100 mL, respectively, 
showing an average removal of 1.1 log by presedimentation.
    The Kansas City Water Services Department collected Bacillus 
subtilis spore samples from January to November 2000 from locations 
before and after one of the facility's six presedimentation basins. 
Sludge generated by the primary clarifier of a softening process was 
recycled to the head of the presedimentation basins during the entire 
study period. In addition, coagulant (polymer and/or ferric sulfate) 
was added prior to presedimentation when raw water turbidity was 
higher. During periods when coagulant was added, mean spore levels 
before and after presedimentation were 102,292 and 13,154 cfu/100 mL, 
respectively, demonstrating a mean removal of 0.9 log. When no ferric 
sulfate or polymer was used, mean presedimentation influent and 
effluent spore levels were 13,296 and 4,609 cfu/100 mL, respectively, 
for an average reduction of 0.46 log.
    The Cincinnati Water Works operates a treatment plant using lamella 
plate settlers for presedimentation. Lamella plate settlers are 
inclined plates added to a sedimentation basin to significantly 
increase the surface area available for particle settling. Coagulant 
(alum and polymer) is added to the raw water prior to presedimentation. 
Total aerobic spore samples were collected from January 1998 through 
December 2000. The mean concentration of spores decreased from 20,494 
cfu/100 mL in the raw water to 4,693 cfu/100 mL in the presedimentation 
effluent, indicating a mean spore removal of 0.64 log.
    In conclusion, literature studies clearly establish that 
sedimentation basins are capable of achieving greater than 0.5 log 
reduction in Cryptosporidium levels. Further, the data supplied by 
utilities on reduction in aerobic spore counts across full scale 
presedimentation basins demonstrate that presedimentation can achieve 
mean reductions of greater than 0.5 log under routine operating 
conditions and over an extended time period. Thus, these data suggest 
that a 0.5 log presumptive credit for Cryptosporidium removal by 
presedimentation is appropriate under certain conditions.
    With respect to the conditions under which the 0.5 log presumptive 
credit for presedimentation is appropriate, the data do not demonstrate 
that this level of removal can be achieved consistently without a 
coagulant. In addition, available data do not establish aerobic spores 
as an effective indicator of Cryptosporidium removal in the absence of 
a coagulant. Thus, supporting data are consistent with a requirement 
that systems apply a coagulant to be eligible for the presumptive 0.5 
log presedimentation credit. Moreover, such a requirement is consistent 
with the Agreement in Principle, which recommends 0.5 log credit for 
presedimentation basins with a coagulant.

[[Page 47690]]

    EPA also has concluded that presedimentation basins need to be 
operated continuously and treat 100% of the plant flow in order to 
reasonably ensure that the process will reduce influent Cryptosporidium 
levels by at least 0.5 log over the course of a full year. The Agency 
recognizes that, depending on influent water quality, some systems may 
determine it is more prudent to operate presedimentation basins 
intermittently in response to fluctuating turbidity levels. By 
proposing these conditions for the presumptive presedimentation credit, 
EPA is not recommending against intermittent operation of 
presedimentation basins. Rather, EPA is attempting to identify the 
conditions under which a 0.5 log presumptive credit for 
presedimentation is warranted.
    In response to the SAB panel recommendation that performance 
criteria other than overflow rate be included if credit is to be given 
for presedimentation, EPA analyzed the relationship between removal of 
spores and reduction in turbidity through presedimentation for the 
three utilities that supplied these data. Results of this analysis are 
summarized in Table IV-12, which shows the relationship between monthly 
mean turbidity reduction and the percent of months when mean spore 
removal was at least 0.5 log.

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    Within the available data set, achieving a mean turbidity reduction 
of at least 0.5 log appears to provide approximately a 90% assurance 
that average spore removal will be 0.5 log or greater. The underlying 
data are shown graphically in Figure IV-4. Based on this information, 
EPA has concluded that it is appropriate to require 0.5 log turbidity 
reduction, determined as a monthly mean of daily turbidity readings, as 
an operating condition for the 0.5 log presumptive Cryptosporidium 
treatment credit for presedimentation. Further, EPA is proposing that 
systems must meet the 0.5 log turbidity reduction requirement in at 
least 11 of the 12 previous months on an ongoing basis to remain 
eligible for the presedimentation credit.

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    c. Request for comment. EPA requests comment on the proposed 
criteria for awarding credit to presedimentation. EPA would 
particularly appreciate comment on the following issues:
    [sbull] Whether the information cited in this proposal supports the 
proposed credit for presedimentation and the operating conditions under 
which the credit will be awarded;
    [sbull] Additional information that either supports or suggest 
modifications to the proposed performance criteria and presumptive 
credit;
    [sbull] Today's proposal requires systems using presedimentation to 
sample after the presedimentation basin, and these systems are not 
eligible to receive additional presumptive Cryptosporidium removal 
credit for presedimentation. However, systems are also required to 
collect samples prior to chemical treatment, and EPA recognizes that 
some plants provide chemical treatment to water prior to, or during, 
presedimentation. EPA requests comment on how this situation should be 
handled under the LT2ESWTR.
    [sbull] Whether and under what conditions factors like low 
turbidity raw water, infrequent sludge removal, and wind would make 
compliance with the 0.5 log turbidity removal requirement infeasible.
6. Bank Filtration
    a. What is EPA proposing today? EPA is proposing to award 
additional Cryptosporidium treatment credit (0.5 or 1.0 log) for 
systems that implement bank filtration as a pre-treatment technique if 
it meets the design criteria specified in this section. To be eligible 
for credit as a pre-treatment technique, bank filtration collection 
devices must meet the following criteria:
    [sbull] Wells are drilled in an unconsolidated, predominantly sandy 
aquifer, as determined by grain-size analysis of recovered core 
material--the recovered core must contain greater than 10% fine-grained 
material (grains less than 1.0 mm diameter) in at least 90% of its 
length;
    [sbull] Wells are located at least 25 feet (in any direction) from 
the surface water source to be eligible for 0.5 log credit; wells 
located at least 50 feet from the source surface water are eligible for 
1.0 log credit;
    [sbull] The wellhead must be continuously monitored for turbidity 
to ensure that no system failure is occurring. If the monthly average 
of daily maximum turbidity values exceeds 1 NTU then the system must 
report this finding to the State. The system must also conduct an 
assessment to determine the cause of the high turbidity levels in the 
well and consult with the State regarding whether previously allowed 
credit is still appropriate.
    Systems using existing bank filtration as pretreatment to a 
filtration plant at the time the systems are required to conduct 
Cryptosporidium monitoring, as described in section IV.A, must sample 
the well effluent for the purpose of determining bin classification. 
Where bin classification is based on monitoring the well effluent, 
systems are not eligible to receive additional credit for

[[Page 47692]]

bank filtration. In these cases, the performance of the bank filtration 
process in reducing Cryptosporidium levels will be reflected in the 
monitoring results and bin classification.
    Systems using bank filtered water without additional filtration 
typically must collect source water samples in the surface water (i.e., 
prior to bank filtration) to determine bin classification. This applies 
to systems using bank filtration to meet the Cryptosporidium removal 
requirements of the IESWTR or LT1ESWTR under the provisions for 
alternative filtration demonstration in 40 CFR 141.173(b) or 
141.552(a). Note that the proposed bank filtration criteria for 
Cryptosporidium removal credit under the LT2ESWTR do not apply to 
existing State actions to provide alternative filtration 
Cryptosporidium removal credit for IESWTR or LT1ESWTR compliance.
    In the case of systems that use GWUDI sources without additional 
filtration and that meet all the criteria for avoiding filtration in 40 
CFR 141.71, samples must be collected from the ground water (e.g., the 
well). Further, such systems must comply with the requirements of the 
LT2ESWTR that apply to unfiltered systems, as described in section 
IV.B.
    b. How was this proposal developed? This section describes the bank 
filtration treatment process, provides more detail on the aquifer types 
and ground water collection devices that are eligible for bank 
filtration credit, and describes the data supporting the proposed 
requirements.
    Bank filtration is a water treatment process that makes use of 
surface water that has naturally infiltrated into ground water via the 
river bed or bank(s) and is recovered via a pumping well. Stream-bed 
infiltration is typically enhanced by the pumping action of near-stream 
wells (e.g., water supply, irrigation). Bank filtrate is water drawn 
into a pumping well from a nearby surface water source which has 
traveled through the subsurface, either vertically, horizontally or 
both, mixing to some degree with other ground water. Through bank 
filtration, microorganisms and other particles are removed by contact 
with the aquifer materials.
    The bank filtration removal process performs most efficiently when 
the aquifer is comprised of granular materials with open pore-space for 
water flow around the grains. In these granular porous aquifers, the 
flow path is meandering, thereby providing ample opportunity for the 
organism to come into contact with and attach to a grain surface. 
Although detachment can occur, it typically occurs at a very slow rate 
so that organisms remain attached to a grain for long periods. When 
ground water travel times from source water to well are long or when 
little or no detachment occurs, most organisms will become inactivated 
before they can enter a well. Thus, bank filtration relies on removal, 
but also, in some cases, on inactivation to protect wells from pathogen 
contamination.
Only Wells Located in Unconsolidated, Predominantly Sandy Aquifers Are 
Eligible
    Only granular aquifers are eligible for bank filtration credit. 
Granular aquifers are those comprised of sand, clay, silt, rock 
fragments, pebbles or larger particles and minor cement. The aquifer 
material is required to be unconsolidated, with subsurface samples 
friable upon touch. Uncemented granular aquifers are typically formed 
by alluvial or glacial processes. Such aquifers are usually identified 
on a detailed geologic map (e.g., labeled as Quaternary alluvium).
    Under today's proposal, a system seeking Cryptosporidium removal 
credit must characterize the aquifer at the well site to determine 
aquifer properties. At a minimum, the aquifer characterization must 
include the collection of relatively undisturbed, continuous, core 
samples from the surface to a depth equal to the bottom of the well 
screen. The proposed site must have substantial core recovery during 
drilling operations; specifically, the recovered core length must be at 
least 90% of the total projected depth to the well screen.
    Samples of the recovered core must be submitted to a laboratory for 
sieve analysis to determine grain size distribution over the entire 
recovered core length. Each sieve sample must be acquired at regular 
intervals over the length of the recovered core, with one sample 
representing a composite of each two feet of recovered core. A two-foot 
sampling interval reflects the necessity to sample the core frequently 
without imposing an undue burden. Because it is anticipated that wells 
will range from 50 to 100 foot in depth, a two-foot sampling interval 
will result in about 25 to 50 samples for analysis. Each sampled 
interval must be examined to determine if more than ten percent of the 
grains in that interval are less than 1.0 mm in diameter (18 
sieve size). In the U.S. Department of Agriculture soil classification 
system, the 18 sieve separates very coarse sands from coarse 
sands. The length of core (based on the samples from two-foot 
intervals) with more than ten percent of the grains less than 1.0 mm in 
diameter must be summed to determine the overall core length with 
sufficient fine-grained material so as to provide adequate removal. An 
aquifer is eligible for removal credit if at least 90% of the sampled 
core length contains sufficient fine-grained material as defined in 
this section.
    Cryptosporidium oocysts have a natural affinity for attaching to 
fine-grained material. A study of oocyst removal in sand columns shows 
greater oocyst removal in finer-grained sands than in coarser-grained 
sands (Harter et al. 2000). The core sampling procedure described in 
this section is designed to measure the proportion of fine-grained 
sands (grains less than 1.0 mm in diameter) so as to ensure that a 
potential bank filtration site is capable of retarding transport (or 
removing) oocysts during ground water flow from the source surface 
water to the water supply well. The value of 1.0 mm for the bounding 
size of the sand grains was determined based on calculations performed 
by Harter using data from Harter et al. (2000). Harter showed that, for 
ground water velocities typical of a bank filtration site (1.5 to 15 m/
day), a typical bank filtration site composed of grains with a diameter 
of 1.0 mm would achieve at least 1.0 log removal over a 50 foot 
transport distance. Larger-sized grains would achieve less removal, all 
other factors being equal.
    Alluvial and glacial aquifers are complex mixtures of sand, gravel 
and other sized particles. Particles of similar size are often grouped 
together in the subsurface, due to sorting by flowing water that 
carries and then deposits the particles. Where there exists significant 
thickness of coarse-grained particles, such as gravels, with few finer 
materials, there is limited opportunity for oocyst removal. When the 
total gravel thickness, as measured in a core, exceeds 10%, it is more 
likely (based on analysis of ground water flow within mixtures 
containing differing-sized grains) that the gravel-rich intervals are 
interconnected. Interconnected gravel can form a continuous, 
preferential flow path from the source surface water to the water 
supply well. Where such preferential flow paths exist, a preponderance 
of the total ground water flow occurs within the preferential flow 
path, ground water velocity is higher, and natural filtration is 
minimal. A proposed bank filtration site is acceptable if at least 90% 
of the core length contains grains with sufficient fine-grained 
material (diameter less than 1.0 mm); that is, it is acceptable if the 
core contains less than 10% gravel-rich intervals.
    Aquifer materials with significant fracturing are capable of 
transmitting

[[Page 47693]]

ground water at high velocity in a direct flow path with little time or 
opportunity for die-off or removal of microbial pathogens. Consolidated 
aquifers, fractured bedrock, and karst limestone are aquifers in which 
surface water may enter into a pumping well by flow along a fracture, a 
solution-enhanced fracture conduit, or other preferential pathway. 
Microbial pathogens found in surface water are more likely to be 
transported to a well via these direct or preferential pathways. 
Cryptosporidium outbreaks have been associated with consolidated 
aquifers, such as a fractured chalk aquifer (Willocks et al. 1998) or a 
karst limestone (solution-enhanced fractured) aquifer (Bergmire-Sweat 
et al. 1999). These outbreaks show that the oocyst removal performance 
of consolidated aquifers is undermined by preferential water flow and 
oocyst transport through rock fractures or through rock dissolution 
zones. Wells located in these aquifers are not eligible for bank 
filtration credit because the flow paths are direct and the average 
ground water velocity is high, so that little inactivation or removal 
would be expected. Therefore, only unconsolidated aquifer are eligible 
for bank filtration oocyst removal credit.
    A number of devices are used for the collection of ground water 
including horizontal and vertical wells, spring boxes, and infiltration 
galleries. Among these, only horizontal and vertical wells are eligible 
for log removal credit. The following discussion presents 
characteristics of ground water collection devices and the basis for 
this proposed requirement.
    Horizontal wells are designed to capture large volumes of surface 
water recharge. They typically are constructed by the excavation of a 
central vertical caisson with laterals that extend horizontally from 
the caisson bottom in all directions or only under the riverbed. 
Horizontal wells are usually shallower than vertical wells because of 
the construction expense. Ground water flow to a horizontal well that 
extends under surface water is predominantly downward. In contrast, 
ground water flow to a vertical well adjacent to surface water may be 
predominantly in the horizontal direction. Surface water may have a 
short ground water flow path to a horizontal well if the well extends 
out beyond the bank.
    Hancock et al. (1998) analyzed samples from eleven horizontal wells 
and found Cryptosporidium, Giardia or both in samples from five of 
those wells. These data suggest that some horizontal wells may not be 
capable of achieving effective Cryptosporidium removal by bank 
filtration. Insufficient data are currently available to suggest that 
horizontal well distances from surface water should be greater than 
distances established for vertical wells. Two ongoing studies in 
Wyoming (Clancy Environmental Consultants 2002) and Nebraska (Rice 
2002) are collecting data at horizontal well sites.
    A spring box is located at the ground surface and is designed to 
contain spring outflow and protect it from surface contamination until 
the water is utilized. Spring boxes are typically located where natural 
processes have enhanced and focused ground water discharge into a 
smaller area and at a faster volumetric flow rate than elsewhere (i.e., 
a spring). Often, localized fracturing or solution enhanced channels 
are the cause of the focused discharge to the spring orifice. Fractures 
and solution channels have significant potential to transport microbial 
contaminants so that natural filtration may be poor. Thus, spring boxes 
are not proposed to be eligible for bank filtration credit.
    Cryptosporidium monitoring results (Hancock et al. 1998) and 
outbreaks are used to evaluate ground water collection devices. Hancock 
et al. sampled thirty five springs for Cryptosporidium oocysts and 
Giardia cysts. Most springs were used as drinking water sources and 
sampling was conducted to determine if the spring should be considered 
as a GWUDI source. Cryptosporidium oocysts were found in seven springs; 
Giardia cysts were found in five springs; and either oocysts or cysts 
were found in nine springs (26%). A waterborne cryptosporidiosis 
outbreak in Medford, Oregon (Craun et al. 1998) is associated with a 
spring water supply collection device. Also, a more recent, smaller 
outbreak of giardiasis in an Oregon campground is associated with a PWS 
using a spring. The high percentage of springs contaminated with 
pathogenic protozoan, the association with recent outbreaks, and an 
apparent lack of bank filtration capability indicate that spring boxes 
must not be eligible for bank filtration credit.
    An infiltration gallery (or filter crib) is typically a slotted 
pipe installed horizontally into a trench and backfilled with granular 
material. The gallery is designed to collect water infiltrating from 
the surface or to intercept ground water flowing naturally toward the 
surface water (Symons et al. 2000). In some treatment plants, surface 
water is transported to a point above an infiltration gallery and then 
allowed to infiltrate. The infiltration rate may be manipulated by 
varying the properties of the backfill or the nature of the soil-water 
interface. Because the filtration properties of the material overlying 
an infiltration gallery may be designed or purposefully altered to 
optimize oocyst removal or for other reasons, this engineered system is 
not bank filtration, which relies solely on the natural properties of 
the system.
    A 1992 cryptosporidiosis outbreak in Talent, Oregon was associated 
with poor performance of an infiltration gallery underneath Bear Creek 
(Leland et al. 1993). In this case, the ground water-surface water 
interface and the engineered materials beneath did not sufficiently 
reduce the high oocyst concentration present in the source water. The 
association of an infiltration gallery with an outbreak, the design 
that relies on engineered materials rather than the filtration 
properties of natural filtration media, and the shallow depth of 
constructed infiltration galleries, such that they typically are not 
located greater than 25 feet from the surface and surface water 
recharge, all indicate that infiltration galleries must not be eligible 
for bank filtration credit.
    EPA notes that under the demonstration of performance credit 
described in section IV.C.17, States may consider awarding 
Cryptosporidium removal credit to infiltration galleries where the 
State determines, based on site-specific testing with a State-approved 
protocol, that such credit is appropriate (i.e., that the process 
reliably achieves a specified level of Cryptosporidium removal on a 
continuing basis).
Wells Located 25 Feet From the Surface Water Source Are Eligible for 
0.5 Log Credit; Wells Located 50 Feet From the Surface Water Source Are 
Eligible for 1.0 Log Credit
    A vertical or horizontal well located adjacent to a surface water 
body is eligible for bank filtration credit if there is sufficient 
ground water flow path length to effectively remove oocysts. For 
vertical wells, the wellhead must be located at least 25 horizontal 
feet from the surface water body for 0.5 log Cryptosporidium removal 
credit and at least 50 horizontal feet from the surface water body for 
1.0 log Cryptosporidium removal credit. For horizontal wells, the 
laterals must be located at least 25 feet distant from the normal-flow 
surface water riverbed for 0.5 log Cryptosporidium removal credit and 
at least 50 feet distant from the normal-flow surface water riverbed 
for 1.0 log Cryptosporidium removal credit.
    The ground water flow path to a vertical well is the measured 
distance from the edge of the surface water body, under high flow 
conditions (determined by the mapped extent of the 100 year

[[Page 47694]]

floodplain elevation boundary or floodway, as defined in Federal 
Emergency Management Agency (FEMA) flood hazard maps), to the wellhead. 
The ground water flow path to a horizontal well is the measured 
distance from the bed of the river under normal flow conditions to the 
closest horizontal well lateral.
    The floodway is defined by FEMA as the area of the flood plain 
where the water is likely to be deepest and fastest. The floodway is 
shown on FEMA digital maps (known as Q3 flood data maps), which are 
available for 11,990 communities representing 1,293 counties in the 
United States. Systems may identify the distance to surface water using 
either the 100 year return period flood elevation boundary or by 
determining the floodway boundary using methods similar to those used 
in preparing FEMA flood hazard maps. The 100 year return period flood 
elevation boundary is expected to be wider than the floodway but that 
difference may vary depending on local conditions. Approximately 19,200 
communities in the United States have flood hazard maps that show the 
100 year return period flood elevation boundary. If local FEMA floodway 
hazard maps are unavailable or do not show the 100 year flood elevation 
boundary, then the utility must determine either the floodway or 100 
year flood elevation boundary.
    The separation distance proposed for Cryptosporidium removal credit 
is based, in part, on measured data for the removal of oocyst surrogate 
biota in full-scale field studies. A variety of surrogate and indicator 
organisms were analyzed in each study evaluated for today's proposal. 
However, only two non-pathogenic organisms, anaerobic clostridia spores 
and aerobic endospores, are resistant to inactivation in the 
subsurface, approximately similar in size and shape to oocysts, and 
sufficiently ubiquitous in both surface water and ground water so that 
log removal can be calculated during passage across the surface water--
ground water interface and during transport within the aquifer.
    Anaerobic spores are typically estimated at about 0.3-0.4 [mu]m in 
diameter as compared with 4-6 [mu]m for oocysts. Aerobic spores, such 
as endospores of the bacterium Bacillus subtilis, are slightly larger 
than anaerobic spores, typically 0.5 x 1.0 x 2.0 [mu]m in diameter 
(Rice et al. 1996). Experiments conducted by injecting Bacillus 
subtilis spores into a gravel aquifer show that they can be very mobile 
in the subsurface environment (Pang et al. 1998). As presented in the 
following discussion, available data indicate similar removal of both 
aerobic and anaerobic spores, either during passage across the surface 
water--ground water interface or during ground water flow. These data 
suggest that anaerobic spores, like aerobic spores, may be suitable 
surrogate measures of Cryptosporidium removal by bank filtration.
    Available data establish that during bank filtration, significant 
removal of anaerobic and aerobic spores can occur during passage across 
the surface water-ground water interface, with lesser removal occurring 
during ground water transport within the aquifer away from that 
interface. The ground water-surface water interface is typically 
comprised of finer grained material that lines the bottom of the 
riverbed. Typically, the thickness of the interface is small, typically 
a few inches to a foot. The proposed design criteria of 25 and 50 feet 
for 0.5 and 1.0 log Cryptosporidium removal credit, respectively, are 
based on EPA's analysis of pathogen and surrogate monitoring data from 
bank filtration sites. Most of these data are from studies of aquifers 
developed in Dutch North Sea margin sand dune fields and, therefore, 
represent optimal removal conditions consistent with a homogenous, well 
sorted (by wind), uniform sand filter.
    Medema et al. (2000) measured 3.3 log removal of anaerobic spores 
during transport over a 13 m distance from the Meuse River into 
adjacent ground water. Arora et al. (2000) measured greater than 2.0 
log removal of anaerobic spores during transport from the Wabash River 
to a horizontal collector well. Havelaar et al. (1995) measured 3.1 log 
removal of anaerobic spores during transport over a 30 m distance from 
the Rhine River to a well and 3.6 log removal over a 25 m distance from 
the Meuse River to a well. Schijven et al. (1998) measured 1.9 log 
removal of anaerobic spores over a 2 m distance from a canal to a 
monitoring well. Using aerobic spores, Wang et al. (2001) measured 1.8 
log removal over a 2 foot distance from the Ohio river to a monitoring 
well beneath the river.
    During transport solely within shallow ground water (i.e., not 
including removal across the surface water-ground water interface), 
Medema et al. (2000) measured approximately 0.6 log removal of 
anaerobic spores over a distance of 39 feet. Using aerobic spores, Wang 
et al. (2001) measured 1.0 log removal of aerobic spores over a 48 foot 
distance from a monitoring well beneath a river to a horizontal well 
lateral.
    At distances relatively far from an injection well in a deep, 
anaerobic aquifer, thereby minimizing the effects of injection, 
Schijven et al. measured negligible removal of anaerobic spores over a 
30 m distance. However, few bank filtration systems occur in deeper, 
anaerobic ground water so these data may not apply to a typical bank 
filtration system in the United States.
    These data demonstrate that during normal and low surface water 
elevations, the surface water-ground water interface performs 
effectively to remove microbial contamination. However, there will 
typically be high water elevation periods during the year, especially 
on uncontrolled rivers, that alter the nature and performance of the 
interface due to flood scour, typically for short periods. During these 
periods, lower removals would be expected to occur.
    Averaging Cryptosporidium oocyst removal over the period of a year 
requires consideration of both high and low removal periods. During 
most of the year, high log removal rates would be expected to 
predominate (e.g., 3.3 log removal over 42 feet) due to the removal 
achieved during passage across the surface water-ground water 
interface. During short periods of flooding, substantially lower 
removal rates may occur (e.g., 0.5 log removal over 39 feet) due to 
scouring of the riverbed and removal of the protective, fine-grained 
material. By considering all time intervals with differing removal 
rates over the period of a year, EPA is proposing that 0.5 log removal 
over 25 feet (8 m) and 1.0 log removal over 50 feet (16 m) are 
reasonable estimates of the average performance of a bank filtration 
system over a year. This proposal is generally supported by colloidal 
filtration theory modeling results using data characteristic of the 
aquifers in Louisville and Cincinnati and column studies of oocyst 
transport in sand (Harter et al. 2000).
Wells must be continuously monitored for turbidity
    Under the Surface Water Treatment Rule (40 CFR 141.73(b)(1)) the 
turbidity level of slow sand filtered water must be 1 NTU or less in 
95% of the measurements taken each month. Turbidity sampling is 
required once every four hours, but may be reduced to once per day 
under certain conditions. Although slow sand filtration is not bank 
filtration, similar pathogen removal mechanisms are expected to occur 
in both processes. Just as turbidity monitoring is used to provide 
assurance that the removal credit assigned to a slow sand filter is 
being realized, EPA

[[Page 47695]]

is proposing continuous turbidity monitoring for all bank filtration 
wells that receive credit.
    If monthly average turbidity levels (based on daily maximum values 
in the well) exceed 1 NTU, the system is required to report to the 
State and present an assessment of whether microbial removal has been 
compromised. If the State determines that microbial removal has been 
compromised, the system must not receive credit for bank filtration 
until the problem has been remediated. The turbidity performance 
requirement for bank filtration is less strict than that for slow sand 
filtration because, unlike slow sand filtration, bank filtration is a 
pre-treatment technique followed by conventional or direct filtration.
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    In summary, EPA believes that the measured full-scale field data 
from operating bank filtration systems, the turbidity monitoring 
provision, and the design criteria for aquifer material, collection 
device type, and setback distance, together provide assurance that the 
presumptive log removal credit will be achieved by bank filtration 
systems that conform to the requirements in today's proposal.
    c. Request for comment. The Agency requests comment on the 
following issues concerning bank filtration:
    [sbull] The performance of bank filtration in removing 
Cryptosporidium or surrogates to date at sites currently using this 
technology (e.g. sites with horizontal wells).
    [sbull] The use of other methods (e.g., geophysical methods such as 
ground penetrating radar) to complement or supplant core drilling to 
determine site suitability for bank filtration credit.
    [sbull] The number of GWUDI systems in each State (i.e., the number 
of systems having at least one GWUDI source) where bank filtration has 
been utilized as the primary filtration barrier (e.g., no other 
physical removal technologies follow); also, the method that was used 
by the State to determine that each

[[Page 47696]]

system was achieving 2 log removal of Cryptosporidium.
    [sbull] For GWUDI systems where natural or alternative filtration 
(e.g. bank filtration or artificial recharge) is used in combination 
with a subsequent filtration barrier (e.g., bag or cartridge filters) 
to meet the 2 log Cryptosporidium removal requirement of the IESWTR or 
LT1ESWTR, how much Cryptosporidium removal credit has the State awarded 
(or is the State willing to grant if the bags/cartridges were found to 
be achieving < 2.0 logs) for the natural or alternative filtration 
process and how did the State determine this value?
    [sbull] The proposed Cryptosporidium removal credit and associated 
design criteria, including any additional information related to this 
topic.
    [sbull] Suitable separation distance(s) to be required between 
vertical or horizontal wells and adjacent surface water.
    [sbull] Testing protocols and procedures for making site specific 
determinations of the appropriate level of Cryptosporidium removal 
credit to award to bank filtration processes.
    [sbull] Information on the data and methods suitable for predicting 
Cryptosporidium removal based on the available data from surrogate and 
indicator measurements in water collection devices.
    [sbull] The applicability of turbidity monitoring or other process 
monitoring procedures to indicate the ongoing performance of bank 
filtration processes.
7. Lime Softening
    a. What is EPA proposing today? Lime softening is a drinking water 
treatment process that uses precipitation with lime and other chemicals 
to reduce hardness and enhance clarification prior to filtration. Lime 
softening can be categorized into two general types: (1) Single-stage 
softening, which is used to remove calcium hardness and (2) two-stage 
softening, which is used to remove magnesium hardness and greater 
levels of calcium hardness. A single-stage softening plant includes a 
primary clarifier and filtration components. A two-stage softening 
plant also includes a secondary clarifier located between the primary 
clarifier and filter. In some two-stage softening plants, a portion of 
the flow bypasses the first clarifier.
    EPA has determined that lime softening plants in compliance with 
IESWTR or LT1ESWTR achieve a level of Cryptosporidium removal 
equivalent to conventional treatment plants (i.e., average of 3 log). 
Consequently, lime softening plants that are placed in Bins 2-4 as a 
result of Cryptosporidium monitoring incur the same additional 
treatment requirements as conventional plants. However, EPA is 
proposing that two-stage softening plants be eligible for an additional 
0.5 log Cryptosporidium treatment credit. To receive the 0.5 log 
credit, the plant must have a second clarification stage between the 
primary clarifier and filter that is operated continuously, and both 
clarification stages must treat 100% of the plant flow. In addition, a 
coagulant must be present in both clarifiers (may include metal salts, 
polymers, lime, or magnesium precipitation).
    b. How was this proposal developed? The lime softening process is 
used to remove hardness, primarily calcium and magnesium, through 
chemical precipitation followed by sedimentation and filtration. The 
addition of lime increases pH, causing the metal ions to precipitate. 
Other contaminants can coalesce with the precipitates and be removed in 
the subsequent settling and filtration processes. While elevated pH has 
been shown to inactivate some microorganisms like viruses (Battigelli 
and Sobsey, 1993, Logsdon et al. 1994), current research indicates that 
Cryptosporidium and Giardia are not inactivated by high pH (Logsdon et 
al. 1994, Li et al. 2001). A two-stage lime softening plant has the 
potential for additional Cryptosporidium removal because of the 
additional sedimentation process.
    Limited data are available on the removal of Cryptosporidium by the 
lime softening treatment process. EPA has evaluated data from a study 
by Logsdon et al. (1994), which investigated removal of Giardia and 
Cryptosporidium in full scale lime softening plants. In addition, the 
Agency has considered data provided by utilities on the removal of 
aerobic spores in softening plants. These data are summarized in the 
following paragraphs.
    Logsdon et al. (1994) measured levels of Cryptosporidium and 
Giardia in the raw, settled, and filtered water of 13 surface water 
plants using lime softening. Cryptosporidium was detected in the raw 
water at 5 utilities: one single-stage plant and four two-stage plants. 
Using measured oocyst levels, Cryptosporidium removal by sedimentation 
was 1.0 log in the single-stage plant and 1.1 to 2.3 log in the two-
stage plants. Cryptosporidium was found in two filtered water samples 
of the single stage plant, leading to calculated removals from raw to 
filtered water of 0.6 and 2.2 log. None of the two-stage plants had 
Cryptosporidium detected in the filtered water. Based on detection 
limits, calculated Cryptosporidium removals from raw to filtered water 
in the two-stage plants ranged from 2.67 to 3.85 
log.
    Giardia removal across sedimentation was 0.9 log for a 
single-stage plant and ranged from 0.8 to 3.2 log for two-stage plants, 
based on measured cyst levels. Removal of Giardia from raw water 
through filtration was calculated using detection limits as 
1.5 log in a single-stage plant and ranged from 
0.9 to 3.3 log in two-stage plants.
    While results from the Logsdon et al. study are constrained by 
sample number and method detection limits, they suggest that two-stage 
softening plants may achieve greater removal of Cryptosporidium than 
single-stage plants. The authors concluded that two stages of 
sedimentation, each preceded by effective flocculation of particulate 
matter, may increase removal of protozoa. Additionally, the authors 
stated that consistent achievement of flocculation that results in 
effective settling in each sedimentation basin is the key factor in 
this treatment process.

Removal of Aerobic Spores by Softening Plants

    Additional information on the microbial removal efficiency of the 
lime softening process comes from data provided by softening plants on 
removal of aerobic spores. While few treatment plants have sufficient 
concentrations of oocysts to directly calculate a Cryptosporidium 
removal efficiency, some plants have high concentrations of aerobic 
spores in the raw water. Spores may serve as an indicator of 
Cryptosporidium removal by sedimentation and filtration (Dugan et al. 
2001).
    The following two-stage softening plants provided data on removal 
of aerobic spores: St. Louis, MO, Kansas City, MO, and Columbus, OH (2 
plants). Cryptosporidium data were also collected at these utilities, 
but it was not possible to calculate oocyst removal due to low raw 
water detection rates. Data on removal of aerobic spores by these 
softening plants is summarized in Table IV-14.

[[Page 47697]]



                    Table IV-14.--Summary of Aerobic Spore Removal Data From Softening Plants
----------------------------------------------------------------------------------------------------------------
                                                                        Mean log removal of aerobic spores
                                                                 -----------------------------------------------
                              Plant                                   Primary        Secondary
                                                                     clarifier       clarifier    Across plant *
----------------------------------------------------------------------------------------------------------------
St. Louis.......................................................             1.7             1.1             3.8
Kansas City.....................................................             2.4               0             3.4
Columbus Plant 1................................................             1.2             1.6             3.1
Columbus Plant 2................................................             1.3             2.4            4.2
----------------------------------------------------------------------------------------------------------------
* Excludes removal in pre-sedimentation basins; calculated spore removal may underestimate actual removal due to
  filter effluent levels below quantitation limits.

    The City of St. Louis Water Division operates a two-stage lime 
softening process preceded by presedimentation. Ferric sulfate and 
polymer coagulants are added at various points in the process. St. 
Louis collected Bacillus subtilis spore samples between June 1998 and 
September 2000. During this time period, the mean spore concentration 
entering the softening process (i.e., after presedimentation) was 8,132 
cfu/100 mL. The log removal values shown in Table IV-14 are based on 
average spore concentrations following primary clarification, secondary 
clarification, and filtration. However, spore levels in some filtered 
water samples were below the method detection limit, so that the true 
mean spore removal across the plant may have been higher than indicated 
by the calculated value.
    The Kansas City Water Services Department plant includes two-stage 
lime softening with pre-sedimentation and sludge recycle. Bacillus 
subtilis spore data were collected from this plant during January 
through November 2000. The mean spore concentration entering the lime 
softening process (after presedimentation) was 5,965 cfu/100 mL. Mean 
spore levels following primary clarification, secondary clarification, 
and filtration were 21.1, 25.7, and 2.6 cfu/100 mL, respectively. 
Corresponding log removal values are shown in Table IV-14. Note that 
the average spore concentration in the effluent of the secondary 
clarifier was essentially equivalent to the effluent of the primary 
clarifier, indicating that little removal occurred in the secondary 
clarifier. This result may have been due to the high removal achieved 
in the primary clarifier and, consequently, the relatively low 
concentration of spores entering the second clarifier. As with the St. 
Louis plant, many of the filtered water observations were below method 
detection limits, so actual log removal across the plant may have been 
higher than the calculated value.
    The City of Columbus operates two lime softening plants, each of 
which has two clarification stages. Coagulant is added prior to the 
first clarification stage but lime is not added until the second 
clarifier (i.e., first clarifier is not a softening stage). Between 
1997 and 2000, samples for total aerobic spores were collected 
approximately monthly at each plant from raw water, following each 
clarification basin, and after filtration. Mean spore concentrations in 
the raw water sources for the two plants were 10,619 cfu/100 mL (Plant 
1) and 22,595 cfu/100 mL (Plant 2). Mean log removals occurring in the 
two clarification stages and across the plant are shown for each plant 
in Table IV-14.
    These data indicate that two-stage softening plants can remove high 
levels of Cryptosporidium, and, in particular, that a second 
clarification stage can achieve 0.5 log or greater removal. Three of 
the four plants that provided data on removal of aerobic spores 
achieved greater than 1 log reduction in the second clarifier. Kansas 
City, the one plant which achieved little removal in the second 
clarifier, achieved a mean 2.4 log removal in the primary clarifier. 
This was approximately 1 log more reduction than achieved in the 
primary clarifiers of the other three plants, so that the spore 
concentration entering the second clarifier in Kansas City may have 
been too low to serve as an indicator of removal efficiency. 
Consequently, EPA has concluded that these data support an additional 
Cryptosporidium treatment credit of 0.5 log for a two-stage softening 
plant.
    EPA is proposing as a condition of the 0.5 log additional credit 
that a coagulant, which could include excess lime and soda ash or 
precipitation of magnesium hydroxide, be present in both clarifiers. 
This requirement is necessary to ensure that significant particulate 
removal occurs in both clarification stages. Logsdon et al. (1994) 
identified effective flocculation as being a key factor for removal of 
protozoa in softening plants. Among the softening plants that provided 
data on aerobic spore removal, St. Louis added ferric and polymer 
coagulants at different points in the process, and the two Columbus 
plants added lime to the second clarifier. Consequently, a requirement 
that plants add a coagulant, which may be lime, in the secondary 
clarifier is consistent with the data used to support the 0.5 log 
additional credit.
    The Science Advisory Board (SAB) reviewed the proposed 
Cryptosporidium treatment credit for lime softening and supporting 
information, as presented in the November 2001 pre-proposal draft of 
the LT2ESWTR (USEPA 2001g). In written comments from a December 2001 
meeting of the Drinking Water Committee, the SAB panel concluded that 
both single- and two-stage softening generally outperform conventional 
treatment due to the heavy precipitation that occurs. Further, the 
panel found that 0.5 log of additional Cryptosporidium removal is an 
average value for a two-stage lime softening plant. However, the SAB 
stated that the additional credit for two-stage softening should be 
given only if all the water passes through both stages. Today's 
proposal is consistent with these recommendations by the SAB.
    EPA notes that by including a presumptive credit for softening 
plants, today's proposal differs from the Stage 2 M-DBP Agreement in 
Principle, which recommends up to 1 log additional Cryptosporidium 
treatment credit for softening plants based on demonstration of 
performance, but no additional presumptive credit.
    c. Request for comment. EPA requests comment on the proposed 
criteria for awarding credit to lime softening plants. EPA would 
particularly appreciate comment on the following issues:
    [sbull] Whether the information and analyses presented in this 
proposal supports an additional 0.5 log credit for two-stage softening, 
and the associated criteria necessary for credit.
    [sbull] Additional information that either support or suggest 
modifications to the proposed criteria and credit.
8. Combined Filter Performance
    a. What is EPA proposing today? This toolbox component will grant 
additional credit towards Cryptosporidium

[[Page 47698]]

treatment requirements to certain plants that maintain finished water 
turbidity at levels significantly lower than currently required. EPA is 
proposing to award an additional 0.5 log Cryptosporidium treatment 
credit to conventional and direct filtration plants that demonstrate a 
turbidity level in the combined filter effluent (CFE) less than or 
equal to 0.15 NTU in at least 95 percent of the measurements taken each 
month. Compliance with this criterion must be based on measurements of 
the CFE every four hours (or more frequently) that the system serves 
water to the public. This credit is not available to membrane, bag/
cartridge, slow sand, or DE plants, due to the lack of documented 
correlation between effluent turbidity and Cryptosporidium removal in 
these processes.
    b. How was this proposal developed? Turbidity is an optical 
property measured from the amount of light scattered by suspended 
particles in a solution. It is a method defined parameter that can 
detect the presence of a wide variety of particles in water (e.g., 
clay, silt, mineral particles, organic and inorganic matter, and 
microorganisms), but it cannot provide specific information on particle 
type, number, or size. Turbidity is used as an indicator of raw and 
finished water quality and treatment performance. Turbidity spikes in 
filtered water indicate a potential for breakthrough of pathogens.
    Under the IESWTR and LT1ESWTR, combined filter effluent turbidity 
in conventional and direct filtration plants must be less than or equal 
to 0.3 NTU in 95% of samples taken each month and must never exceed 1 
NTU. These plants are also required to conduct continuous monitoring of 
turbidity for each individual filter, and provide an exceptions report 
to the State when certain criteria for individual filter effluent 
turbidity are exceeded (described in 63 FR 69487, December 16, 1998) 
(USEPA 1998a).
    The Stage 2 M-DBP Advisory Committee recommended that systems 
receive an additional 0.5 log Cryptosporidium removal credit for 
maintaining 95th percentile combined filter effluent turbidity below 
0.15 NTU, which is one half of the current required level of 0.3 NTU. 
In considering the technical basis to support this recommendation, EPA 
has reviewed studies that evaluated the efficiency of granular media 
filtration in removing Cryptosporidium when operating at different 
effluent turbidity levels.
    For the IESWTR, EPA estimated that plants would target filter 
effluent turbidity in the range of 0.2 NTU in order to ensure 
compliance with a turbidity standard of 0.3 NTU. Similarly, EPA has 
estimated that plants relying on meeting a turbidity standard of 0.15 
NTU in 95% of samples will consistently operate below 0.1 NTU in order 
to ensure compliance. Consequently, to assess the impact of compliance 
with the lower finished water turbidity standard, EPA compared 
Cryptosporidium removal efficiency when effluent turbidity is below 0.1 
NTU with removal efficiency when effluent turbidity is in the range of 
0.1 to 0.2 NTU. Results from applicable studies are summarized in Table 
IV-15 and are discussed in the following paragraphs.

                                 Table IV-15.--Studies of Cryptosporidium Removal at Different Effluent Turbidity Levels
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                      Average of log     Filtered effluent
            Microorganism                removals            turbidity                Experiment design                        Researcher
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cryptosporidium.....................            4.39  <=0.1 NTU..............  Pilot-scale....................  Patania et al. (1995).
                                                3.55  0.1 and
                                                       <=0.2 NTU
Giardia.............................            4.23  <=0.1 NTU
                                                3.22  0.1 and
                                                       <=0.2 NTU
Cryptosporidium.....................            4.09  <=0.1 NTU..............  Bench-scale....................  Emelko et al. (1999).
                                                3.58  0.1 and
                                                       <=0.2 NTU
Cryptosporidium.....................            3.76  <=0.1 NTU                Pilot-scale....................  Dugan et al. (2001).
                                                2.56  0.1 and
                                                       <=0.2 NTU
--------------------------------------------------------------------------------------------------------------------------------------------------------

    Patania et al. (1995) conducted pilot-scale studies at four 
locations to evaluate the removal of seeded Cryptosporidium and 
Giardia, turbidity, and particles. Treatment processes, coagulants, and 
coagulant doses differed among the four locations. Samples of filter 
effluent were taken at times of stable operation and filter maturation. 
Analysis of summary data from the seeded runs at all locations shows 
that average Cryptosporidium removal was greater by more than 0.5 log 
when effluent turbidity was less than 0.1 NTU, in comparison to removal 
with effluent turbidity in the range 0.1 to 0.2 NTU (see Table IV-15).
    Emelko et al. (1999) used a bench scale dual media filter to study 
Cryptosporidium removal during both optimal and challenged operating 
conditions. Water containing a suspension of kaolinite (clay) was 
spiked with oocysts, coagulated in-line with alum, and filtered. Oocyst 
removal was evaluated during stable operation when effluent turbidity 
was below 0.1 NTU. Removal was also measured after a hydraulic surge 
that caused process upset, and with coagulant addition terminated. 
These later two conditions resulted in effluent turbidities greater 
than 0.1 NTU and decreased removal of Cryptosporidium. As shown in 
Table IV-15, average removal of Cryptosporidium during periods with 
effluent turbidity below 0.1 NTU was approximately 0.5 log greater than 
when effluent turbidity was between 0.1 to 0.2 NTU.
    Dugan et al. (2001) evaluated Cryptosporidium removal in a pilot 
scale conventional treatment plant. Sixteen filtration runs seeded with 
Cryptosporidium were conducted at different raw water turbidities and 
coagulation conditions. Eleven of the runs had an effluent turbidity 
below 0.1 NTU, and five runs had effluent turbidity between 0.1 and 0.2 
NTU. For runs where the calculated Cryptosporidium removal was 
concentration limited (i.e., effluent values were non-detect), the 
method detection limit was used to calculate the values shown in Table 
IV-15. Using this conservative estimate, average Cryptosporidium 
removal with effluent turbidity below 0.1 NTU exceeded by more than 1 
log the average removal observed with effluent turbidity between 0.1 to 
0.2 NTU.
    In summary, these three studies all support today's proposal in 
showing that plants consistently operating below 0.1 NTU can achieve an 
additional 0.5 log or greater removal of Cryptosporidium than when 
operating between 0.1 and 0.2 NTU. Because EPA expects plants relying 
on compliance with a 0.15 NTU standard will consistently operate below 
0.1 NTU, the

[[Page 47699]]

Agency has determined it is appropriate to propose an additional 0.5 
log treatment credit for plants meeting this standard.
    The SAB reviewed the proposed additional 0.5 log Cryptosporidium 
removal credit for systems maintaining very low CFE turbidity, as 
presented in the November 2001 pre-proposal draft of the LT2ESWTR 
(USEPA 2001g). The SAB also reviewed a potential additional 1.0 log 
Cryptosporidium removal credit for systems achieving very low 
individual filter effluent (IFE) turbidity, which is addressed in 
section IV.C.16 of today's proposal.
    In written comments from a December 2001 meeting of the Drinking 
Water Committee, the SAB panel stated that additional credit for lower 
finished water turbidity is consistent with what is known in both pilot 
and full-scale operational experiences for Cryptosporidium removal. 
Recognizing that IESWTR requirements for lowering turbidity in the 
treated water will result in lower concentrations of Cryptosporidium, 
the panel affirmed that even further lowering of turbidity will result 
in further reductions in Cryptosporidium in the filter effluent. 
However, the SAB concluded that limited data were presented to show the 
exact removal that can be achieved, and recommended that no additional 
credit be given to plants that demonstrate CFE turbidity of 0.15 NTU or 
less. The SAB recommended that 0.5 log credit be given to plants 
achieving IFE turbidity in each filter less than 0.15 NTU in 95% of 
samples each month.
    In responding to this recommendation from the SAB, EPA acknowledges 
the difficulty in precisely quantifying Cryptosporidium removal through 
filtration based on effluent turbidity levels. Nevertheless, EPA finds 
that available data consistently show that removal of Cryptosporidium 
is increased by 0.5 log or greater when filter effluent turbidity is 
reduced to levels reflecting compliance with a 0.15 NTU standard, in 
comparison to compliance with a 0.3 NTU standard. Consequently, EPA has 
concluded that it is appropriate to propose this 0.5 log presumptive 
treatment credit for systems achieving very low CFE turbidity.
Measurement of Low Level Turbidity
    Another important aspect of proposing to award additional removal 
credit for lower finished water turbidity is the performance of 
turbidimeters in measuring turbidity below 0.3 NTU. The following 
paragraphs summarize results from several studies that evaluated low 
level measurement of turbidity by different on-line and bench top 
instruments. Note that because compliance with the CFE turbidity limit 
is based on 4-hour readings, either on-line or bench top turbidimeters 
may be used. EPA believes that results from these studies indicate that 
currently available turbidity monitoring equipment is capable of 
reliably assessing turbidity at levels below 0.1 NTU, provided 
instruments are well calibrated and maintained.
    The 1997 NODA for the IESWTR (67 FR 59502, Nov. 3, 1997) (USEPA 
1997a) discusses issues relating to the accuracy and precision of low 
level turbidity measurements. This document cites studies (Hart et al. 
1992, Sethi et al. 1997) suggesting that large tolerances in instrument 
design criteria have led to turbidimeters that provide different 
turbidity readings for a given suspension.
    At the time of IESWTR NODA, EPA had conducted performance 
evaluation (PE) studies of turbidity samples above 0.3 NTU. A 
subsequent PE study (USEPA 1998e), labeled WS041, was carried out to 
address concern among the Stage 1 M-DBP Federal Advisory Committee 
regarding the ability to reliably measure lower turbidity levels. The 
study involved distribution of different types of laboratory prepared 
standard solutions with reported turbidity values of 0.150 NTU or 0.160 
NTU. The results of this study are summarized in Table IV-16.
BILLING CODE 6560-50-P
[GRAPHIC] [TIFF OMITTED] TP11AU03.010

BILLING CODE 6560-50-C
    The data summarized in Table IV-16 indicate a positive bias for all 
instruments when compared against a reported ``true value.'' On-line 
instruments in this study had a larger positive bias and higher 
standard deviation (RSD approximately 50 percent). The positive bias is 
consistent with previous PE studies (USEPA 1998e) and suggests that 
error in turbidimeter readings may be generally conservative (i.e., 
systems will operate

[[Page 47700]]

at lower than required effluent turbidity levels).
    Letterman et al. (2001) evaluated the effect of turbidimeter design 
and calibration methods on inter-instrument performance, comparing 
bench top to on-line instruments and instruments within each of those 
categories from different manufacturers. The study used treated water 
collected from the filter effluent of water treatment plants. Reported 
sample turbidity values ranged from 0.05 to 1 NTU. Samples were 
analyzed in a laboratory environment. The results are consistent with 
those of the WS041 study, specifically the positive bias of on-line 
instruments. However, Letterman et al. found generally poor agreement 
among different on-line instruments and between bench-top and on-line 
instruments. The authors also observed that results were independent of 
the calibration method, though certain experiments suggested that 
analyst experience may have some effect on turbidity readings from 
bench-top instruments.
    Sadar (1999) conducted an intra-instrument study of low level 
turbidity measurements among instruments from the same manufacturer. 
This study was performed under well-controlled laboratory conditions. 
Intra-instrument variation among different models and between bench top 
and on-line instruments occurred but at significantly lower levels than 
the Letterman et al. inter-instrument study. Newer instruments also 
tended to read lower than older instruments, which the author 
attributed to a reduction in stray light and lower sensitivities in the 
newer instruments. Sadar also found a generally positive bias when 
comparing on-line to bench-top and when comparing all instruments to a 
prepared standard.
    The American Society for Testing and Materials (ASTM) has issued 
standard test methods for measurement of turbidity below 5 NTU by on-
line (ASTM 2001) and static (ASTM 2003) instrument modes. The methods 
specify that the instrument should permit detection of turbidity 
differences of 0.01 NTU or less in waters having turbidities of less 
than 1.00 NTU (ASTM 2001) and 5.0 NTU (ASTM 2003), respectively. Inter-
laboratory study data included with the method for a known turbidity 
standard of 0.122 NTU show an analyst relative deviation of 7.5% and a 
laboratory relative deviation of 16% (ASTM 2003).
    In summary, the data collected in these studies of turbidity 
measurement indicate that currently available monitoring equipment can 
reliably measure turbidity at levels of 0.1 NTU and lower. However, 
this requires rigorous calibration and verification procedures, as well 
as diligent maintenance of turbidity monitoring equipment (Burlingame 
1998, Sadar 1999). Systems that pursue additional treatment credit for 
lower finished water turbidity must develop the procedures necessary to 
ensure accurate and reliable measurement of turbidity at levels of 0.1 
NTU and less. EPA guidance for the microbial toolbox will provide 
direction to water systems on developing these procedures.
    c. Request for comment. EPA invites comment on the following issues 
regarding the proposed Cryptosporidium treatment credit for combined 
filter performance:
    [sbull] Do the studies cited here support awarding 0.5 log credit 
for CFE <= 0.15 NTU 95% of the time?
    [sbull] Does currently available turbidity monitoring technology 
accurately distinguish differences between values measured near 0.15 
NTU?
9. Roughing Filter
    a. What is EPA proposing today? The Stage 2 M-DBP Agreement in 
Principle recommends a 0.5 log presumptive credit towards additional 
Cryptosporidium treatment requirements for roughing filters. However, 
the Agreement further specifies that EPA is to determine the design and 
implementation criteria under which the credit would be awarded. Upon 
subsequent review of available literature, EPA is unable to identify 
design and implementation conditions for roughing filters that would 
provide reasonable assurance of achieving a 0.5 log removal of oocysts. 
Consequently, EPA is not proposing presumptive credit for 
Cryptosporidium removal by roughing filters. Today's proposal does, 
though, include a 0.5 log credit for a second granular media filter 
following coagulation and primary filtration (see section IV.C.13).
    b. How was this proposal developed? Roughing filtration is a 
technique used primarily in developing countries to remove solids from 
high turbidity source waters prior to treatment with slow sand filters. 
Typically, roughing filters consist of a series of sedimentation tanks 
filled with progressively smaller diameter media in the direction of 
flow. The media can be gravel, plastic, crushed coconut, rice husks, or 
a similar locally available material. The flow direction in roughing 
filters can be either horizontal or vertical, and vertical roughing 
filters can be either upflow or downflow. The media in the tanks 
effectively reduce the vertical settling distance of particles to a 
distance of a few millimeters. As sediment builds on the media, it 
eventually sloughs off and begins to accumulate in the lower section of 
the filter, while simultaneously regenerating the upper portions of the 
filter. The filters require periodic cleaning to remove the collected 
silt.
    Review of the scientific and technical literature pertaining to 
roughing filters has identified no information on removal of 
Cryptosporidium. Information is available on removal of suspended 
solids, turbidity, particles, fecal coliforms and some algae, but none 
of these has been demonstrated to be an indicator of Cryptosporidium 
removal by roughing filters. Moreover, roughing filters are not 
preceded by a coagulation step, and studies have found that some 
potential surrogates, such as aerobic spores, are not conservative 
indicators of Cryptosporidium removal by filtration when a coagulant is 
not present (Yates et al. 1998, Dugan et al. 2001). Thus, it is unclear 
how to relate results from studies of the removal of other particles by 
roughing filters to potential removal of Cryptosporidium.
    In addition, some studies have observed very poor removal of 
Cryptosporidium by rapid sand filters when a coagulant is not used 
(Patania et al. 1995, Huck et al. 2000). Based on these findings, it is 
expected that there would be situations where a roughing filter would 
not achieve 0.5 log Cryptosporidium removal. Because available data are 
insufficient to determine the conditions that would be necessary for a 
roughing filter to achieve 0.5 log Cryptosporidium removal, EPA is 
unable to propose this credit. The following discussion describes four 
studies that analyzed the effectiveness of roughing filters for 
removing solids, turbidity, particles, fecal coliforms, and algae.
    Wegelin et al. (1987) conducted pilot-scale studies on the use of 
horizontal roughing filters to reduce solids, turbidity, and particles. 
Testing was performed to determine the influence of different design 
parameters on filter performance. Data from the parameter testing was 
used to establish an empirical model to simulate filtrate quality as a 
function of filter length and time for a given filter configuration. 
Using the mathematical model, the researchers found that long filters 
(10 m) at low filtration rates (0.5 m/h) were capable of reducing high 
suspended solids concentrations (1000 mg/L TSS) down to less than 3 mg/
L.
    Further work by Wegelin (1988) evaluated roughing filters as 
pretreatment for slow sand filters for

[[Page 47701]]

waters with variable and seasonably high suspended solids 
concentrations. This study collected data on roughing filters in Peru, 
Colombia, Sudan, and Ghana. Table IV-17 summarizes data for three of 
the roughing filters. These filters were capable of reducing peak 
turbidities by 80 to 90 percent. Further, the Peruvian and Colombian 
filters reduced fecal coliforms by 77 and 89 percent, respectively. The 
Sudanese filter may have removed around 90 percent of the fecal 
coliforms, but specific values were not given. Data collected from 
roughing filters in Ghana on algae removal indicate that the 
Merismopedia (0.5 [mu]m) and Chlorophyta (2-10 [mu]m), which are 
comparable in size to Cryptosporidium oocysts, were completely removed 
from the water in mature filters, and that some removal of Chlorophyta, 
but not Merismopedia, occurred in filters after three days of 
operation. However, the removal of these organisms has not been 
correlated with Cryptosporidium oocyst removal.

                              Table IV-17.--Roughing Filter Data From Wegelin, 1988
----------------------------------------------------------------------------------------------------------------
            Location                  Azpita, Peru     El Retiro, Colombia     Blue Nile Health Project, Sudan
----------------------------------------------------------------------------------------------------------------
Roughing Filter Type............  Downflow...........  Upflow (multi-layer  Horizontal-flow.
                                                        filter).
Filtration Rate.................  0.30 m/h (0.98 ft/   0.74 m/h (2.43 f/    0.3 m/h (0.98 ft/hr).
                                   hr).                 hr).
Design Capacity.................  35 m3/d............  790 m3/d...........  5 m3/d.
---------------------------------
                                                 Turbidity (NTU)
----------------------------------------------------------------------------------------------------------------
Raw Water.......................  50-200.............  10-150.............  40-500
Roughing Filter Effluent........  15-40..............  5-15...............  5-50
---------------------------------
                                            Fecal Coliforms (/100 mL)
----------------------------------------------------------------------------------------------------------------
Raw Water.......................  700................  16,000.............  300
Roughing Filter Effluent........  160................  1,680..............  <25
----------------------------------------------------------------------------------------------------------------

    oller (1993) details the mechanisms of particle removal that occur 
in roughing filters. The conclusions are similar to those drawn by 
Wegelin et al. (1987). Particle analysis reviewed by Boller indicates 
that after seven days of operation, the four stage pilot filter 
utilized by Wegelin et al. (1987) removed more than 98 percent of 
particles sized 1.1 [mu]m, and greater than 99 percent of particles 
sized 3.6 [mu]m. After 62 days, only 80 percent of particles sized 1.1 
[mu]m were removed, while 90 percent of particles sized 3.6 [mu]m were 
removed. Boller did not give the solids loading on the tested filter, 
and particle removal was not correlated to Cryptosporidium oocyst 
removal.
    Collins et al. (1994) investigated solids and algae removal with 
pilot scale vertical downflow roughing filters. Gravel media size, 
filter depth, and flow rate were varied to determine which design 
variables had the greatest effect on filter performance. Results 
indicated that the most influential design parameters for removing 
solids from water, in order of importance, were filter length, gravel 
size, and hydraulic flow rate. For algae removal, the most influential 
design parameters were hydraulic flow rate, filter length, and gravel 
size. Solids removal was better in filters that had been ripened with 
algae for 5-7 days. However, extrapolation of these results to 
Cryptosporidium removal could not be made.
    c. Request for comment. The Agency requests comment on the 
information that has been presented about roughing filters, and 
specifically the question of whether and under what conditions roughing 
filters should be awarded a 0.5 log credit for removal of 
Cryptosporidium. EPA also requests information on specific studies of 
Cryptosporidium oocyst removal by roughing filters, or from studies of 
the removal of surrogate parameters that have been shown to correlate 
with oocyst removal in roughing filters.
10. Slow Sand Filtration
    a. What is EPA proposing today? Slow sand filtration is defined in 
40 CFR 141.2 as a process involving passage of raw water through a bed 
of sand at low velocity (generally less than 0.4 m/h) resulting in 
substantial particulate removal by physical and biological mechanisms. 
Today's proposal allows systems using slow sand filtration as a 
secondary filtration step following a primary filtration process (e.g., 
conventional treatment) to receive an additional 2.5 log 
Cryptosporidium treatment credit. There must be no disinfectant 
residual in the influent water to the slow sand filtration process to 
be eligible for credit.
    Note that this proposed credit differs from the credit proposed for 
slow sand filtration as a primary filtration process. EPA has 
concluded, based on treatment studies described in section III.D, that 
plants using well designed and well operated slow sand filtration as a 
primary filtration process can achieve an average Cryptosporidium 
removal of 3 log (Schuler and Ghosh, 1991, Timms et al. 1995, Hall et 
al. 1994). Consequently, as described in section IV.A, EPA is proposing 
that plants using slow sand filtration as a primary filtration process 
receive a 3 log credit towards Cryptosporidium treatment requirements 
associated with Bins 2-4 under the LT2ESWTR (i.e., credit equivalent to 
a conventional treatment plant).
    The proposed 2.5 log credit for slow sand filtration as part of the 
microbial toolbox applies only when it is used as a secondary 
filtration step, following a primary filtration process like 
conventional treatment. While the removal mechanisms that make slow 
sand filtration effective as a primary filtration process would also be 
operative when used as a secondary filtration step, EPA has little data 
on this specific application. The Agency is proposing 2.5 log credit 
for slow sand filtration as a secondary filtration step, in comparison 
to 3 log credit as a primary filtration process, as a conservative 
measure reflecting greater uncertainty. In addition, the proposed 2.5 
log credit for slow sand filtration as part of the microbial toolbox is 
consistent with the recommendation in the Stage 2 M-DBP Agreement in 
Principle.
    b. How was this proposal developed? The Stage 2 M-DBP Agreement in 
Principle recommends that slow sand filtration receive 2.5 log or 
greater Cryptosporidium treatment credit when used in addition to 
existing treatment that achieves compliance with the

[[Page 47702]]

IESWTR or LT1ESWTR. Slow sand filtration is not typically used as a 
secondary filtration step following conventional treatment or other 
primary filtration processes of similar efficacy. However, EPA expects 
that slow sand filtration would achieve significant removal of 
Cryptosporidium in such a treatment train.
    While there is a significant body of data demonstrating the 
effectiveness of slow sand filtration for Cryptosporidium removal as a 
primary filtration process, as described in section III.D, EPA has 
limited data on the effectiveness of slow sand filtration when used as 
a secondary filtration step. Hall et al. (1994) evaluated oocyst 
removal for a pilot scale slow sand filter following a primary 
filtration process identified as a rapid gravity filter. The combined 
treatment train of a primary filtration process followed by slow sand 
filtration achieved greater than 3 log Cryptosporidium removal in three 
of five experimental runs, while approximately 2.5 log reduction was 
observed in the other two runs. In comparison, Hall et al. (1994) 
reported slow sand filtration alone to achieve at least a 3 log removal 
of oocysts in each of four experimental runs when not preceded by a 
primary filtration process. The authors offered no explanation for 
these results, but measured oocyst removals may have been impacted by 
limitations with the analytical method.
    Removal of microbial pathogens in slow sand filters is complex and 
is believed to occur through a combination of physical, chemical, and 
biological mechanisms, both on the surface (schmutzdecke) and in the 
interior of the filter bed. It is unknown if the higher quality of the 
water that would be influent to a slow sand filter when used as a 
secondary filtration step would impact the efficiency of the filter in 
removing Cryptosporidium. Based on the limited data on the performance 
of slow sand filtration as a secondary filtration step, and in 
consideration of the recommendation of the Advisory Committee, EPA is 
proposing only a 2.5 log additional Cryptosporidium treatment credit 
for this application.
    c. Request for comment. The Agency requests comment on whether the 
available data are adequate to support awarding a 2.5 log 
Cryptosporidium removal credit for slow sand filtration applied as a 
secondary filtration step, along with any additional information 
related to this application.
11. Membrane Filtration
    a. What is EPA proposing today? EPA is proposing criteria for 
awarding credit to membrane filtration processes for removal of 
Cryptosporidium. To receive removal credit, the membrane filtration 
process must: (1) Meet the basic definition of a membrane filtration 
process, (2) have removal efficiency established through challenge 
testing and verified by direct integrity testing, and (3) undergo 
periodic direct integrity testing and continuous indirect integrity 
monitoring during use. The maximum removal credit that a membrane 
filtration process is eligible to receive is equal to the lower value 
of either:

--The removal efficiency demonstrated during challenge testing OR
--The maximum log removal value that can be verified through the direct 
integrity test (i.e., integrity test sensitivity) used to monitor the 
membrane filtration process.

    By the criteria in today's proposal, a membrane filtration process 
could potentially meet the Bin 4 Cryptosporidium treatment requirements 
of this proposal. These criteria are described in more detail below. 
EPA is developing a Membrane Filtration Guidance Manual that provides 
additional information and procedures for meeting these criteria (USEPA 
2003e). A draft of this guidance is available in the docket for today's 
proposal (http://www.epa.gov/edocket/).
Definition of a Membrane Filtration Process
    For the purpose of this proposed rule, membrane filtration is 
defined as a pressure or vacuum driven separation process in which 
particulate matter larger than 1 [mu]m is rejected by a nonfibrous, 
engineered barrier, primarily through a size exclusion mechanism, and 
which has a measurable removal efficiency of a target organism that can 
be verified through the application of a direct integrity test. This 
definition is intended to include the common membrane technology 
classifications: microfiltration (MF), ultrafiltration (UF), 
nanofiltration (NF), and reverse osmosis (RO). MF and UF are low-
pressure membrane filtration processes that are primarily used to 
remove particulate matter and microbial contaminants. NF and RO are 
membrane separation processes that are primarily used to remove 
dissolved contaminants through a variety of mechanisms, but which also 
remove particulate matter via a size exclusion mechanism.
    In today's proposal, the critical distinction between membrane 
filtration processes and bag and cartridge filters, described in 
section IV.C.12, is that the integrity of membrane filtration processes 
can be directly tested. Based on this distinction, EPA is proposing 
that membrane material configured into a cartridge filtration device 
that meets the definition of membrane filtration and that can be direct 
integrity tested according to the criteria specified in this section is 
eligible for the same removal credit as a membrane filtration process.
    Membrane devices can be designed in a variety of configurations 
including hollow-fiber modules, hollow-fiber cassettes, spiral-wound 
elements, cartridge filter elements, plate and frame modules, and 
tubular modules among others. In today's proposal, the generic term 
module is used to refer to all of these various configurations and is 
defined as the smallest component of a membrane unit in which a 
specific membrane surface area is housed in a device with a filtrate 
outlet structure. A membrane unit is defined as a group of membrane 
modules that share common valving that allows the unit to be isolated 
from the rest of the system for the purpose of integrity testing or 
other maintenance.
Challenge Testing
    A challenge test is defined as a study conducted to determine the 
removal efficiency (i.e., log removal value) of the membrane filtration 
media. The removal efficiency demonstrated during challenge testing 
establishes the maximum removal credit that a membrane filtration 
process is eligible to receive, provided this value is less than or 
equal to the maximum log removal value that can be verified by the 
direct integrity test (as described in the following subsection). 
Challenge testing is a product specific rather than a site specific 
requirement. At the discretion of the State, data from challenge 
studies conducted prior to promulgation of this regulation may be 
considered in lieu of additional testing. However, the prior testing 
must have been conducted in a manner that demonstrates a removal 
efficiency for Cryptosporidium commensurate with the treatment credit 
awarded to the process. Guidance for conducting challenge testing to 
meet the requirements of the rule is provided in the Membrane 
Filtration Guidance Manual (USEPA 2003e). Challenge testing must be 
conducted according to the following criteria:
    [sbull] Challenge testing must be conducted on a full-scale 
membrane module identical in material and construction to the membrane 
modules proposed for use in full-scale treatment facilities. 
Alternatively, challenge testing may be conducted on a smaller membrane 
module, identical in material and similar in construction to the full-

[[Page 47703]]

scale module, if testing meets the other requirements listed in this 
section.
    [sbull] Challenge testing must be conducted using Cryptosporidium 
oocysts or a surrogate that has been determined to be removed no more 
efficiently than Cryptosporidium oocysts. The organism or surrogate 
used during challenge testing is referred to as the challenge 
particulate. The concentration of the challenge particulate must be 
determined using a method capable of discretely quantifying the 
specific challenge particulate used in the test. Thus, gross water 
quality measurements such as turbidity or conductivity cannot be used.
    [sbull] The maximum allowable feed water concentration used during 
a challenge test is based on the detection limit of the challenge 
particulate in the filtrate, and is determined according to the 
following equation:

Maximum Feed Concentration = 3.16 x 10\6\ x (Filtrate Detection Limit)

This will allow the demonstration of up to 6.5 log removal during 
challenge testing if the challenge particulate is removed to the 
detection limit.
    [sbull] Challenge testing must be conducted under representative 
hydraulic conditions at the maximum design flux and maximum design 
system recovery as specified by the manufacturer. Flux is defined as 
the flow per unit of membrane area. Recovery is defined as the ratio of 
filtrate volume produced by a membrane to feed water volume applied to 
a membrane over the course of an uninterrupted operating cycle. An 
operating cycle is bounded by two consecutive backwash or cleaning 
events. In the context of this rule, recovery does not consider losses 
that occur due to the use of filtrate in backwashing or cleaning 
operations.
    [sbull] Removal efficiency of a membrane filtration process is 
determined from the results of the challenge test, and expressed in 
terms of log removal values as defined by the following equation:

LRV = LOG10(Cf)-LOG10(Cp)

where LRV = log removal value demonstrated during challenge testing; 
Cf = the feed concentration used during the challenge test; 
and Cp = the filtrate concentration observed during the 
challenge test. For this equation to be valid, equivalent units must be 
used for the feed and filtrate concentrations. If the challenge 
particulate is not detected in the filtrate, then the term 
Cp is set equal to the detection limit. A single LRV is 
calculated for each membrane module evaluated during the test.
    [sbull] The removal efficiency of a membrane filtration process 
demonstrated during challenge testing is expressed as a log removal 
value (LRVC-Test). If fewer than twenty modules are tested, 
then LRVC-Test is assigned a value equal to the lowest of 
the representative LRVs among the various modules tested. If twenty or 
more modules are tested, then LRVC-Test is assigned a value 
equal to the 10th percentile of the representative LRVs among the 
various modules tested. The percentile is defined by [i/(n+1)] where i 
is the rank of n individual data points ordered lowest to highest. It 
may be necessary to calculate the 10th percentile using linear 
interpolation.
    [sbull] A quality control release value (QCRV) must be established 
for a non-destructive performance test (e.g., bubble point test, 
diffusive airflow test, pressure/vacuum decay test) that demonstrates 
the Cryptosporidium removal capability of the membrane module. The 
performance test must be applied to each production membrane module 
that did not undergo a challenge test in order to verify 
Cryptosporidium removal capability. Production membrane modules that do 
not meet the established QCRV are not eligible for the removal credit 
demonstrated during challenge testing.
    [sbull] Any significant modification to the membrane filtration 
device (e.g., change in the polymer chemistry of the membrane) requires 
additional challenge testing to demonstrate removal efficiency of the 
modified module and to define a new QCRV for the nondestructive 
performance test.
Direct Integrity Testing
    In order to receive removal credit for Cryptosporidium, the removal 
efficiency of a membrane filtration process must be routinely verified 
through direct integrity testing. A direct integrity test is defined as 
a physical test applied to a membrane unit in order to identify and 
isolate integrity breaches. An integrity breach is defined as one or 
more leaks that could result in contamination of the filtrate. The 
direct integrity test method must be applied to the physical elements 
of the entire membrane unit including membranes, seals, potting 
material, associated valving and piping, and all other components which 
under compromised conditions could result in contamination of the 
filtrate.
    The direct integrity tests commonly used at the time of this 
proposal include those that use an applied pressure or vacuum (such as 
the pressure decay test and diffusive airflow test), and those that 
measure the rejection of a particulate or molecular marker (such as 
spiked particle monitoring). Today's proposal does not stipulate the 
use of a particular direct integrity test. Instead, the direct 
integrity test must meet performance criteria for resolution, 
sensitivity, and frequency.
    Resolution is defined as the smallest leak that contributes to the 
response from a direct integrity test. Any direct integrity test 
applied to meet the requirements of this proposed rule must have a 
resolution of 3 [mu]m or less. The manner in which the resolution 
criterion is met will depend on the type of direct integrity test used. 
For example, a pressure decay test can meet the resolution criterion by 
applying a net test pressure great enough to overcome the bubble point 
of a 3 [mu]m hole. A direct integrity test that uses a particulate or 
molecular marker can meet the resolution criterion by applying a marker 
of 3 [mu]m or smaller.
    Sensitivity is defined as the maximum log removal value that can be 
reliably verified by the direct integrity test (LRVDIT). The 
sensitivity of the direct integrity test applied to meet the 
requirements of this proposed rule must be equal to or greater than the 
removal credit awarded to the membrane filtration process. The manner 
in which LRVDIT is determined will depend on the type of 
direct integrity test used. Direct integrity tests that use an applied 
pressure or vacuum typically measure the rate of pressure/vacuum decay 
or the flow of air through an integrity breach. The response from this 
type of integrity test can be related to the flow of water through an 
integrity breach (Qbreach) during normal operation, using 
procedures such as those described in the Membrane Filtration Guidance 
Manual (USEPA 2003e). Once Qbreach has been determined, a 
simple dilution model is used to calculate LRVDIT for the 
specific integrity test application, as shown by the following 
equation:

LRVDIT = LOG10(Qp/(VCF x 
Qbreach))

where LRVDIT = maximum log removal value that can be 
verified by a direct integrity test; Qp = total design 
filtrate flow from the membrane unit; Qbreach = flow of 
water from an integrity breach associated with the smallest integrity 
test response that can be reliably measured; and VCF = volumetric 
concentration factor.
    The volumetric concentration factor is the ratio of the suspended 
solids concentration on the high pressure side of the membrane relative 
to the feed water, and is defined by the following equation:

VCF = Cm/Cf

where Cm is the concentration of particulate matter on the 
high pressure

[[Page 47704]]

side of the membrane that remains in suspension; and Cf is 
the concentration of suspended particulate matter in the feed water. 
The magnitude of the concentration factor depends on the mode of system 
operation and typically ranges from 1 to 20. The Membrane Filtration 
Guidance Manual presents approaches for determining the volumetric 
concentration factor for different operating modes (USEPA 2003e).
    Sensitivity of direct integrity tests that use a particulate or 
molecular marker is determined from the feed and filtrate 
concentrations of the marker. The LRVDIT for this type of 
direct integrity test is calculated according to the following 
equation:

LRVDIT = LOG10(Cf) - 
LOG10(Cp)

where LRVDIT = maximum log removal value that can be 
verified by a direct integrity test; Cf = the typical feed 
concentration of the marker used in the test; and Cp = the 
filtrate concentration of the marker from an integral membrane unit. 
For this equation to be valid, equivalent units must be used for the 
feed and filtrate concentrations. An ideal particulate or molecular 
marker would be completely removed by an integral membrane unit.
    If the sensitivity of the direct integrity test is such that 
LRVDIT is less than LRVC-Test, LRVDIT 
establishes the maximum removal credit that a membrane filtration 
process is eligible to receive. Conversely, if LRVDIT for a 
direct integrity test is greater than LRVC-Test, 
LRVC-Test establishes the maximum removal credit.
    A control limit is defined as an integrity test response which, if 
exceeded, indicates a potential problem with the system and triggers a 
response. Under this proposal, a control limit for a direct integrity 
test must be established that is indicative of an integral membrane 
unit capable of meeting the Cryptosporidium removal credit awarded by 
the State. If the control limit for the direct integrity test is 
exceeded, the membrane unit must be taken off-line for diagnostic 
testing and repair. The membrane unit could only be returned to service 
after the repair has been completed and confirmed through the 
application of a direct integrity test.
    The frequency of direct integrity testing specifies how often the 
test is performed over an established time interval. Most direct 
integrity tests available at the time of this proposal are applied 
periodically and must be conducted on each membrane unit at a frequency 
of not less than once every 24 hours while the unit is in operation. If 
continuous direct integrity test methods become available that also 
meet the sensitivity and resolution criteria described earlier, they 
may be used in lieu of periodic testing.
    EPA is proposing that at a minimum, a monthly report must be 
submitted to the State summarizing all direct integrity test results 
above the control limit associated with the Cryptosporidium removal 
credit awarded to the process and the corrective action that was taken 
in each case.
Continuous Indirect Integrity Monitoring
    The majority of currently available direct integrity test methods 
are applied periodically since the membrane unit must be taken out of 
service to conduct the test. In order to provide some measure of 
process performance between direct integrity testing events, continuous 
indirect integrity monitoring is required. Indirect integrity 
monitoring is defined as monitoring some aspect of filtrate water 
quality that is indicative of the removal of particulate matter. If a 
continuous direct integrity test is implemented that meets the 
resolution and sensitivity criteria described previously, continuous 
indirect integrity monitoring is not required. Continuous indirect 
integrity monitoring must be conducted according to the following 
criteria:
    [sbull] Unless the State approves an alternative parameter, 
continuous indirect integrity monitoring must include continuous 
filtrate turbidity monitoring.
    [sbull] Continuous monitoring is defined as monitoring conducted at 
a frequency of no less than once every 15 minutes.
    [sbull] Continuous monitoring must be separately conducted on each 
membrane unit.
    [sbull] If indirect integrity monitoring includes turbidity and if 
the filtrate turbidity readings are above 0.15 NTU for a period greater 
than 15 minutes (i.e., two consecutive 15-minute readings above 0.15 
NTU), direct integrity testing must be performed on the associated 
membrane units.
    [sbull] If indirect integrity monitoring includes a State-approved 
alternative parameter and if the alternative parameter exceeds a State-
approved control limit for a period greater than 15 minutes, direct 
integrity testing must be performed on the associated membrane units.
    [sbull] EPA is proposing that at a minimum, a monthly report must 
be submitted to the primacy agency summarizing all indirect integrity 
monitoring results triggering direct integrity testing and the 
corrective action that was taken in each case.
    b. How was this proposal developed? The Stage 2 M-DBP Agreement in 
Principle recommends that EPA develop criteria to award Cryptosporidium 
removal credit to membrane filtration processes. Today's proposal and 
the supporting guidance are consistent with the Agreement.
    A number of studies have been conducted which have demonstrated the 
ability of membrane filtration processes to remove pathogens, including 
Cryptosporidium, to below detection levels. A literature review 
summarizing the results of several comprehensive studies was conducted 
by EPA and is presented in Low-Pressure Membrane Filtration for 
Pathogen Removal: Application, Implementation, and Regulatory Issues 
(USEPA 2001h). Many of these studies used Cryptosporidium seeding to 
demonstrate removal efficiencies as high as 7 log. The collective 
results from these studies demonstrate that an integral membrane 
module, i.e., a membrane module without any leaks or defects, with an 
exclusion characteristic smaller than Cryptosporidium, is capable of 
removing this pathogen to below detection in the filtrate, independent 
of the feed concentration.
    Some filtration devices have used membrane media in a cartridge 
filter configuration; however, few data are available documenting their 
ability to meet the requirements for membrane filtration described in 
section IV.C.11.a of this preamble. However, in one study reported by 
Dwyer et al. (2001), a membrane cartridge filter demonstrated 
Cryptosporidium removal efficiencies in excess of 6 log. This study 
illustrates the potentially high removal capabilities of membrane 
filtration media configured into a cartridge filtration device, thus 
providing a basis for awarding removal credits to these devices under 
the membrane filtration provision of the rule, assuming that the device 
meets the definition of a membrane filtration process as well as the 
direct integrity test requirements.
    Today's proposal requires challenge testing of membrane filtration 
processes used to remove Cryptosporidium. As noted in section III.D, 
EPA believes this is necessary due to the proprietary nature of these 
systems and the lack of any uniform criteria for establishing the 
exclusion characteristic of a membrane. Challenge testing addresses the 
lack of a standard approach for characterizing membranes by requiring 
direct verification of removal efficiency. The proposed challenge 
testing is product-specific and not site-specific since the

[[Page 47705]]

intent of this testing is to demonstrate the removal capabilities of 
the membrane product rather than evaluate the feasibility of 
implementing membrane treatment at a specific plant.
    Testing can be conducted using a full-scale module or a smaller 
module if the results from the small-scale module test can be related 
to full-scale module performance. Most challenge studies presented in 
the literature have used full-scale modules, which provide results that 
can be directly related to full-scale performance. However, use of 
smaller modules is considered feasible in the evaluation of removal 
efficiency, and a protocol for challenge testing using small-scale 
modules has been proposed (NSF, 2002a). Since the removal efficiency of 
an integral membrane is a direct function of the membrane material, it 
may be possible to use a small-scale module containing the same 
membrane fibers or sheets used in full-scale modules for this 
evaluation. However, it will be necessary to relate the results of the 
small-scale module test to the nondestructive performance test quality 
control release value that will be used to validate full-scale 
production modules.
    Challenge testing with either Cryptosporidium oocysts or a 
surrogate is permitted. Challenge testing with Cryptosporidium clearly 
provides direct verification of removal efficiency for this pathogen; 
however, several studies have demonstrated that surrogates can provide 
an accurate or conservative measure of Cryptosporidium removal 
efficiency. Since removal of particulate matter larger than 1 [mu]m by 
a membrane filtration process occurs primarily via a size exclusion 
mechanism, the shape and size distribution of the surrogate must be 
selected such that the surrogate is not removed to a greater extent 
than the target organism. Surrogates that have been successfully used 
in challenge studies include polystyrene microspheres and bacterial 
endospores. The bacterial endospore, Bacillus subtilis, has been used 
as a surrogate for Cryptosporidium oocysts during challenge studies 
evaluating pathogen removal by physical treatment processes, including 
membrane filtration (Rice et al. 1996, Fox et al. 1998, Trimboli et al. 
1999, Owen et al, 1999). Studies evaluating cartridge filters have 
demonstrated that polystyrene microspheres can provide an accurate or 
conservative measure of removal efficiency (Long, 1983, Li et al. 
1997). Furthermore, the National Sanitation Foundation (NSF) 
Environmental Technology Verification (ETV) protocol for verification 
testing for physical removal of microbiological and particulate 
contaminants specifies the use of polymeric microspheres of a known 
size distribution (NSF 2002b). Guidance on selection of an appropriate 
surrogate for establishing a removal efficiency for Cryptosporidium 
during challenge testing is presented in the Membrane Filtration 
Guidance Manual (USEPA 2003e).
    The design of the proposed challenge studies is similar to the 
design of the seeding studies described in the literature cited 
earlier. Seeding studies are used to challenge the membrane module with 
pathogen levels orders of magnitude higher than those encountered in 
natural waters. However, elevated feed concentrations can lead to 
artificially high estimates of removal efficiency. To address this 
issue, the feed concentration applied to the membrane during challenge 
studies is capped at a level that will allow the demonstration of up to 
6.5 log removal efficiency if the challenge particulate is removed to 
the detection level.
    Because challenge testing with Cryptosporidium or a surrogate is 
not conducted on every membrane module, it is necessary to establish 
criteria for a non-destructive performance test that can be applied to 
all production membrane modules. Results from a non-destructive test, 
such as a bubble point test, that are correlated with the results of 
challenge testing can be used to establish a quality control release 
value (QCRV) that is indicative of the ability of a membrane filtration 
process to remove Cryptosporidium. The non-destructive test and QCRV 
can be used to verify the Cryptosporidium removal capability of modules 
that are not challenge tested. Most membrane manufacturers have already 
adapted some form of non-destructive testing for product quality 
control purposes and have established a quality control release value 
that is indicative of an acceptable product. It may be possible to 
apply these existing practices for the purpose of verifying the 
capability of a membrane filtration process to remove Cryptosporidium.
    Challenge testing provides a means of demonstrating the removal 
efficiency of an integral membrane module; however, defects or leaks in 
the membrane or other system components can result in contamination of 
the filtrate unless they are identified, isolated, and repaired. In 
order to verify continued performance of a membrane system, today's 
proposal requires direct integrity testing of membrane filtration 
processes used to meet Cryptosporidium treatment requirements. Direct 
integrity testing is required because it is a test applied to the 
physical membrane module and, thus, a direct evaluation of integrity. 
Furthermore, direct integrity methods are the most sensitive integrity 
monitoring methods commonly used at the time of this proposal (Adham et 
al. 1995).
    The most common direct integrity tests apply a pressure or a vacuum 
to one side of a fully wetted membrane and monitor either the pressure 
decay or the volume of displaced fluid over time. However, the 
proprietary nature of these systems makes it impractical to define a 
single direct integrity test methodology that is applicable to all 
existing and future membrane products. Therefore, performance criteria 
have been established for any direct integrity test methodology used to 
verify the removal efficiency of a membrane system. These performance 
criteria are resolution, sensitivity, and frequency.
    As stated previously, the resolution of an integrity test refers to 
the smallest leak that contributes to the response from an integrity 
test. For example, in a pressure decay integrity test, resolution is 
the smallest leak that contributes to pressure loss during the test. 
Today's proposal specifies a resolution of 3 [mu]m or less, which is 
based on the size of Cryptosporidium oocysts. This requirement ensures 
that a leak that could pass a Cryptosporidium oocyst would contribute 
to the response from an integrity test.
    The sensitivity of an integrity test refers to the maximum log 
removal that can be reliably verified by the test. Again using the 
pressure decay integrity test as an example, the method sensitivity is 
a function of the smallest pressure loss that can be detected over a 
membrane unit. Today's proposal limits the log removal credit that a 
membrane filtration process is eligible to receive to the maximum log 
removal value that can be verified by a direct integrity test.
    In order to serve as a useful process monitoring tool for assuring 
system integrity, it is necessary to establish a site-specific control 
limit for the integrity test that corresponds to the log removal 
awarded to the process. A general approach for establishing this 
control limit for some integrity test methods is presented in guidance; 
however, the utility will need to work with the membrane manufacturer 
and State to establish a site-specific control limit appropriate for 
the integrity test used and level of credit awarded. Excursions above 
this limit indicate a potential integrity breach and would trigger 
removal of the suspect unit from service followed by diagnostic testing 
and subsequent repair, as necessary.

[[Page 47706]]

    Most direct integrity tests available at the time of this proposal 
must be applied periodically since it is necessary to take the membrane 
unit out of service to conduct the test. Today's proposal establishes 
the minimum frequency for performing a direct integrity test at once 
per 24 hours. Currently, there is no standard frequency for direct 
integrity testing that has been adopted by all States and membrane 
treatment facilities. In a recent survey, the required frequency of 
integrity testing was found to vary from once every four hours to once 
per week; however, the most common frequency for conducting a direct 
integrity test was once every 24 hours (USEPA 2001h). Specifically, 10 
out of 14 States that require periodic direct integrity testing specify 
a frequency of once every 24 hours. Furthermore, many membrane 
manufacturers of systems with automated integrity test systems set up 
the membrane units to automatically perform a direct integrity test 
once per 24 hours. EPA has concluded that the 24 hour direct integrity 
test frequency ensures that removal efficiency is verified on a routine 
basis without resulting in excessive system downtime.
    Since most direct integrity tests are applied periodically, it is 
necessary to implement some level of continuous monitoring to assess 
process performance between direct integrity test events. In the 
absence of a continuous direct integrity test, continuous indirect 
integrity monitoring is required. Although it has been shown that 
commonly used indirect integrity monitoring methods lack the 
sensitivity to detect small integrity breaches that are of concern 
(Adham et al. 1995), they can detect large breaches and provide some 
assurance that a major failure has not occurred between direct 
integrity test events. Turbidity monitoring is proposed as the method 
of indirect integrity monitoring unless the State approves an alternate 
approach. Available data indicate that an integral membrane filtration 
process can consistently produce water with a turbidity less than 0.10 
NTU, regardless of the feedwater quality. Consequently, EPA is 
proposing that exceedance of a filtrate turbidity value of 0.15 NTU 
triggers direct integrity testing to verify and isolate the integrity 
breach.
    c. Request for comment. EPA requests comment on the following 
issues:
    [sbull] EPA is proposing to include membrane cartridge filters that 
can be direct integrity tested under the definition of a membrane 
filtration process since one of the key differences between membrane 
filtration processes and bag and cartridge filters, within the context 
of this regulation, is the applicability of direct integrity test 
methods to the filtration process. EPA requests comment on the 
inclusion of membrane cartridge filters that can be direct integrity 
tested under the definition of a membrane filtration process in this 
rule.
    [sbull] The applicability of the proposed Cryptosporidium removal 
credits and performance criteria to Giardia lamblia.
    [sbull] Appropriate surrogates, or the characteristics of 
appropriate surrogates, for use in challenge testing. EPA requests data 
or information demonstrating the correlation between removal of a 
proposed surrogate and removal of Cryptosporidium oocysts.
    [sbull] The use of a non-destructive performance test and 
associated quality control release values for demonstrating the 
Cryptosporidium removal capability of membrane modules that are not 
directly challenge tested.
    [sbull] The appropriateness of the minimum direct integrity test 
frequency of once per 24 hours.
    [sbull] The proposed minimum reporting frequency for direct 
integrity testing results above the control limit and indirect 
integrity monitoring results that trigger direct integrity monitoring.
12. Bag and Cartridge Filtration
    a. What is EPA proposing today? EPA is proposing criteria for 
awarding Cryptosporidium removal credit of 1 log for bag filtration 
processes and 2 log for cartridge filtration processes. To receive 
removal credit the process must: (1) Meet the basic definition of a bag 
or cartridge filter and (2) have removal efficiency established through 
challenge testing.
Definition of a Bag or Cartridge Filter
    For the purpose of this rule, bag and cartridge filters are defined 
as pressure driven separation processes that remove particulate matter 
larger than 1 [mu]m using an engineered porous filtration media through 
either surface or depth filtration.
    The distinction between bag filters and cartridge filters is based 
on the type of filtration media used and the manner in which the 
devices are constructed. Bag filters are typically constructed of a 
non-rigid, fabric filtration media housed in a pressure vessel in which 
the direction of flow is from the inside of the bag to outside. 
Cartridge filters are typically constructed as rigid or semi-rigid, 
self-supporting filter elements housed in pressure vessels in which 
flow is from the outside of the cartridge to the inside.
    Although all filters classified as cartridge filters share 
similarities with respect to their construction, there are significant 
differences among the various commercial cartridge filtration devices. 
From a public health perspective, an important distinction among these 
filters is the ability to directly test the integrity of the filtration 
system in order to verify that there are no leaks that could result in 
contamination of the filtrate. Any membrane cartridge filtration device 
that can be direct integrity tested according to the criteria specified 
in section IV.C.11.a is eligible for removal credit as a membrane, 
subject to the criteria specified in that section. Section IV.C.12 
applies to all bag filters, as well as to cartridge filters which 
cannot be direct integrity tested.
Challenge Testing
    In order to receive 1 log removal credit, a bag filter must have a 
demonstrated removal efficiency of 2 log or greater for 
Cryptosporidium. Similarly, to receive 2 log removal credit, a 
cartridge filter must have a demonstrated removal efficiency of 3 log 
or greater for Cryptosporidium. The 1 log factor of safety is applied 
to the removal credit awarded to these filtration devices based on two 
primary considerations. First, the removal efficiency of some bag and 
cartridge filters has been observed to vary by more than 1 log over the 
course of operation (Li et al. 1997, NSF 2001a, NSF 2001b). Second, bag 
and cartridge filters are not routinely direct integrity tested during 
operation in the field; hence, there is no means of verifying the 
removal efficiency of filtration units during routine use. Based on 
these considerations, a conservative approach to awarding removal 
credit based on challenge test results is warranted.
    Removal efficiency must be demonstrated through a challenge test 
conducted on the bag or cartridge filter proposed for use in full-scale 
drinking water treatment facilities for removal of Cryptosporidium. 
Challenge testing is required for specific products and is not intended 
to be site specific. At the discretion of the State, data from 
challenge studies conducted prior to promulgation of this regulation 
may be considered in lieu of additional testing. However, the prior 
testing must have been conducted in a manner that demonstrates a 
removal efficiency for Cryptosporidium commensurate with the treatment 
credit awarded to the process. Guidance on conducting challenge studies 
to demonstrate the Cryptosporidium removal efficiency of filtration 
units is presented in the Membrane Filtration Guidance Manual (USEPA 
2003e). Challenge testing must

[[Page 47707]]

be conducted according to the following criteria:
    [sbull] Challenge testing must be conducted on a full-scale filter 
element identical in material and construction to the filter elements 
proposed for use in full-scale treatment facilities.
    [sbull] Challenge testing must be conducted using Cryptosporidium 
oocysts or a surrogate which is removed no more efficiently than 
Cryptosporidium oocysts. The organism or surrogate used during 
challenge testing is referred to as the challenge particulate. The 
concentration of the challenge particulate must be determined using a 
method capable of discretely quantifying the specific organism or 
surrogate used in the test, i.e., gross water quality measurements such 
as turbidity cannot be used.
    [sbull] The maximum allowable feed water concentration used during 
a challenge test is based on the detection limit of the challenge 
particulate in the filtrate and calculated using one of the following 
equations.
    For bag filters:

Maximum Feed Concentration = 3.16 x 103 x (Filtrate 
Detection Limit)
    For cartridge filters:

Maximum Feed Concentration = 3.16 x 104 x (Filtrate 
Detection Limit)

    This will allow the demonstration of up to 3.5 log removal for bag 
filters and 4.5 log removal for cartridge filters during challenge 
testing if the challenge particulate is removed to the detection limit.
    [sbull] Challenge testing must be conducted at the maximum design 
flow rate specified by the manufacturer.
    [sbull] Each filter must be tested for a duration sufficient to 
reach 100% of the terminal pressure drop, a parameter specified by the 
manufacturer which establishes the end of the useful life of the 
filter. In order to achieve terminal pressure drop during the test, it 
will be necessary to add particulate matter to the test solution, such 
as fine carbon test dust or bentonite clay particles.
    [sbull] Each filter must be challenged with the challenge 
particulate during three periods over the filtration cycle: within 2 
hours of start-up after a new bag or cartridge filter has been 
installed, when the pressure drop is between 45 and 55% of the terminal 
pressure drop, and at the end of the run after the pressure drop has 
reached 100% of the terminal pressure drop.
    [sbull] Removal efficiency of a bag or cartridge filtration process 
is determined from the results of the challenge test, and expressed in 
terms of log removal values as defined by the following equation:

LRV = LOG10(Cf)-LOG10(Cp)

where LRV = log removal value demonstrated during challenge testing; 
Cf = the feed concentration used during the challenge test; 
and Cp = the filtrate concentration observed during the 
challenge test. For this equation to be valid, equivalent units must be 
used for the feed and filtrate concentrations. If the challenge 
particulate is not detected in the filtrate, then the term 
Cp is set equal to the detection limit. An LRV is calculated 
for each filter evaluated during the test.
    [sbull] In order to receive treatment credit for Cryptosporidium 
under this proposed rule, challenge testing must demonstrate a removal 
efficiency of 2 log or greater for bag filtration and 3 log or greater 
for cartridge filtration. If fewer than twenty filters are tested, then 
removal efficiency of the process is set equal to the lowest of the 
representative LRVs among the various filters tested. If twenty or more 
filters are tested, then removal efficiency of the process is set equal 
to the 10th percentile of the representative LRVs among the various 
filters tested. The percentile is defined by [i/(n+1)] where i is the 
rank of n individual data points ordered lowest to highest. It may be 
necessary to calculate the 10th percentile using linear interpolation.
    [sbull] Any significant modification to the filtration unit (e.g., 
changes to the filtration media, changes to the configuration of the 
filtration media, significant modifications to the sealing system) 
would require additional challenge testing to demonstrate removal 
efficiency of the modified unit.
    b. How was this proposal developed? The Stage 2 M-DBP Agreement in 
Principle recommended that EPA develop criteria for awarding 
Cryptosporidium removal credits of 1 log for bag filters and 2 log for 
cartridge filters. Today's proposal is consistent with the Agreement.
    A limited amount of published data are available regarding the 
removal efficiency of bag and cartridge filters with respect to 
Cryptosporidium oocysts or suitable surrogates. The relevant studies 
identified in the literature are summarized in Table IV-18.

     Table IV-18.--Results From Studies of Cryptosporidium or Surrogate Removal by Bag and Cartridge Filters
----------------------------------------------------------------------------------------------------------------
               Process                       Log removal           Organism/surrogate           Reference
----------------------------------------------------------------------------------------------------------------
Bag and cartridge filtration in        1.1 to 2.1.............  3 to 6 [mu]m spheres...  NSF 2001a.
 series.
Cartridge filtration.................  3.5 (average)..........  Cryptosporidium........  Enriquez et al. 1999.
Cartridge filtration.................  3.3 (average)..........  Cryptosporidium........  Roessler, 1998.
Cartridge filtration.................  1.1 to 3.3.............  Cryptosporidium........  Schaub et al. 1993.
Cartridge filtration.................  0.5 to 3.6.............  5.7 [mu]m spheres......  Long, 1983.
Cartridge filtration.................  2.3 to 2.8.............  Cryptosporidium........  Ciardelli, 1996a.
Cartridge filtration.................  2.7 to 3.7.............  Cryptosporidium........  Ciardelli, 1996b.
Prefilter and bag filter in series...  1.9 to 3.2.............  3.7 [mu]m spheres......  NSF 2001b.
Bag filtration.......................  [sim]3.0...............  Cryptosporidium........  Cornwell and
                                                                                          LeChevallier, 2002.
Bag filtration.......................  0.5 to 3.6.............  Cryptosporidium........  Li et al. 1997.
Bag filtration.......................  0.5 to 2.0.............  4.5 [mu]m spheres......  Goodrich et al. 1995.
----------------------------------------------------------------------------------------------------------------

    These data demonstrate highly variable removal performance for 
these processes, ranging from 0.5 log to 3.6 log for both bag and 
cartridge filtration. Results of these studies also show no correlation 
between the pore size rating established by the manufacturer and the 
removal efficiency of a filtration device. In a study evaluating two 
cartridge filters, both with a pore size rating of 3 [mu]m, a 2 log 
difference in Cryptosporidium oocyst removal was observed between the 
two filters (Schaub et al. 1993). Another study evaluated seventeen 
cartridge filters with a range of pore size ratings from 1 [mu]m to 10 
[mu]m and found no correlation with removal efficiency (Long, 1983). Li 
et al. (1997) evaluated three bag filters with similar pore size 
ratings and observed a 3 log difference in

[[Page 47708]]

Cryptosporidium oocyst removal among them. These results indicate that 
bag and cartridge filters may be capable of achieving removal of 
oocysts in excess of 3 log; however, performance can vary significantly 
among products and there appears to be no correlation between pore size 
rating and removal efficiency.
    Based on available data, specific design criteria that correlate to 
removal efficiency cannot be derived for bag and cartridge filters. 
Furthermore, the removal efficiency of these proprietary devices can be 
impacted by product variability, increasing pressure drop over the 
filtration cycle, flow rate, and other operating conditions. The data 
in Table IV-18 were generated from studies performed under a variety of 
operating conditions, many of which could not be considered 
conservative (or worst-case) operation. These considerations lead to 
the proposed challenge testing requirements which are intended to 
establish a product-specific removal efficiency.
    The proposed challenge testing is product-specific and not site-
specific since the intent of this testing is to demonstrate the removal 
capabilities of the filtration device rather than evaluate the 
feasibility of implementing the technology at a specific plant. 
Challenge testing must be conducted using full-scale filter elements in 
order to evaluate the performance of the entire unit, including the 
filtration media, seals, filter housing and other components integral 
to the filtration system. This will improve the applicability of 
challenge test results to full-scale performance. Multiple filters of 
the same type can be tested to provide a better statistical basis for 
estimating removal efficiency.
    Either Cryptosporidium oocysts or a suitable surrogate could be 
used as the challenge particulate during the test. Challenge testing 
with Cryptosporidium provides direct verification of removal 
efficiency; however, some studies have demonstrated that surrogates, 
such as polystyrene microspheres, can provide an accurate or 
conservative measure of removal efficiency (Long 1983, Li et al. 1997). 
Furthermore, the National Sanitation Foundation (NSF) Environmental 
Technology Verification (ETV) protocol for verification testing for 
physical removal of microbiological and particulate contaminants 
specifies the use of polymeric microspheres of a known size 
distribution (NSF 2002b). Guidance on selection of an appropriate 
surrogate for establishing a removal efficiency for Cryptosporidium 
during challenge testing is presented in the Membrane Filtration 
Guidance Manual (USEPA 2003e).
    In order to demonstrate a removal efficiency of at least 2 or 3 log 
for bag or cartridge filters, respectively, it will likely be necessary 
to seed the challenge particulate into the test solution. A criticism 
of published studies that use this approach is that the seeded levels 
are orders of magnitude higher than those encountered in natural waters 
and this could potentially lead to artificially high estimates of 
removal efficiency. To address this issue, the feed concentration 
applied to the filter during challenge studies is capped at a level 
that will allow the demonstration of a removal efficiency up to 4.5 log 
for cartridge filters and 3.5 log for bag filters if the challenge 
particulate is removed to the detection level.
    The removal efficiency of some bag and cartridge filtration devices 
has been shown to decrease over the course of a filtration cycle due to 
the accumulation of solids and resulting increase in pressure drop. As 
an example, Li et al. (1997) observed that the removal of 4.5 [mu]m 
microspheres by a bag filter decreased from 3.4 log to 1.3 log over the 
course of a filtration cycle. Studies evaluating bag and cartridge 
filtration under the NSF ETV program have also shown a degradation in 
removal efficiency over the course of the filtration cycle (NSF 2001a 
and 2001b). In order to evaluate this potential variability, the 
challenge studies are designed to assess removal efficiency during 
three periods of a filtration cycle: within two hours of startup 
following installation of a new filter, between 45% and 55% of terminal 
pressure drop, and at the end of the run after 100% of terminal 
pressure drop is realized.
    Although challenge testing can provide an estimate of removal 
efficiency for a bag or cartridge filtration process, it is not 
feasible to conduct a challenge test on every production filter. This, 
coupled with variability within a product line, could result in some 
production filters that do not meet the removal efficiency demonstrated 
during challenge testing. For membrane filtration processes, this 
problem is addressed through the use of a quality control release value 
established for a non-destructive test, such as a bubble point test or 
pressure hold test, that is correlated to removal efficiency. Since the 
non-destructive test can be applied to all production membrane modules, 
this provides a feasible means of verifying the performance of every 
membrane module used by a PWS. However, the non-destructive tests 
applied to membrane filtration processes cannot be applied to most bag 
and cartridge filtration devices, and EPA is not aware of an 
alternative non-destructive test that can be used with these devices.
    Typical process monitoring for bag and cartridge filtration systems 
includes turbidity and pressure drop to determine when filters must be 
replaced. However, the applicability of either of these process 
monitoring parameters as tools for verifying removal of Cryptosporidium 
has not been demonstrated. Only a few bag or cartridge filtration 
studies have attempted to correlate turbidity removal with removal of 
Cryptosporidium oocysts or surrogates. Li et al. (1997) found that the 
removal efficiency for turbidity was consistently lower than removal 
efficiency for oocysts or microspheres for the three bag filters 
evaluated. Furthermore, none of the filters was capable of consistently 
producing a filtered water turbidity below 0.3 NTU for the waters 
evaluated. The contribution to turbidity from particles much smaller 
than Cryptosporidium oocysts, and much smaller than the mesh size of 
the filter, make it difficult to correlate removal of turbidity with 
removal of Cryptosporidium. Consequently, EPA is proposing a 1 log 
factor of safety to be applied to challenge test results in awarding 
treatment credit to bag and cartridge filters, and is not proposing 
integrity monitoring requirements for these devices.
    c. Request for comment. EPA requests comment on the following 
issues concerning bag and cartridge filters:
    [sbull] The performance of bag and cartridge filters in removing 
Cryptosporidium through all differential pressure ranges in a filter 
run--EPA requests laboratory and field data, along with associated 
quality assurance and quality control information, that will support a 
determination of the appropriate level of Cryptosporidium removal 
credit to award to these technologies.
    [sbull] The performance of bag and cartridge filters in removing 
Cryptosporidium when used in series with other bag or cartridge 
filters--EPA requests laboratory and field data, along with associated 
quality assurance and quality control information, that will support a 
determination of the appropriate level of Cryptosporidium removal 
credit to award to these technologies when used in series.
    [sbull] Appropriate surrogates, or the characteristics of 
appropriate surrogates, for use in challenge testing bag and cartridge 
filters--EPA requests data or information demonstrating the correlation 
between removal of a proposed surrogate and removal of Cryptosporidium 
oocysts.

[[Page 47709]]

    [sbull] The availability of non-destructive tests that can be 
applied to bag and cartridge filters to verify the removal efficiency 
of production filters that are not directly challenge tested--EPA 
requests data or information demonstrating the correlation between a 
proposed non-destructive test and the removal of Cryptosporidium 
oocysts.
    [sbull] The applicability of pressure drop monitoring, filtrate 
turbidity monitoring, or other process monitoring and process control 
procedures to verify the integrity of bag and cartridge filters--EPA 
requests data or information demonstrating the correlation between a 
proposed process monitoring tool and the removal of Cryptosporidium 
oocysts.
    [sbull] The applicability of bag and cartridge filters to different 
source water types and treatment scenarios.
    [sbull] The applicability of the proposed Cryptosporidium removal 
credits and testing criteria to Giardia lamblia.
    [sbull] The use of a 1 log factor of safety for awarding credit to 
bag and cartridge filters--EPA requests comment on whether this is an 
appropriate factor of safety to account for the inability to conduct 
integrity monitoring of these devices, as well as the variability in 
removal efficiency observed over the course of a filtration cycle for 
some filtration devices. This inability creates uncertainty regarding 
both changes in the performance of a given filter during use and 
variability in performance among filters in a given product line. If 
the 1 log factor of safety is higher than necessary to account for 
these factors, should the Agency establish a lower value, such as a 0.5 
log factor of safety?
13. Secondary Filtration
    a. What is EPA proposing today? Today's proposal allows systems 
using a second filtration stage to receive an additional 0.5 log 
Cryptosporidium removal credit. To be eligible for this credit, the 
secondary filtration must consist of rapid sand, dual media, granular 
activated carbon (GAC), or other fine grain media in a separate stage 
following rapid sand or dual media filtration. A cap, such as GAC, on a 
single stage of filtration will not qualify for this credit. In 
addition, the first stage of filtration must be preceded by a 
coagulation step, and both stages must treat 100% of the flow.
    b. How was this proposal developed? Although not addressed in the 
Agreement in Principle, EPA has determined that secondary filtration 
meeting the criteria described in this section will achieve additional 
removal of Cryptosporidium oocysts. Consequently, additional removal 
credit may be appropriate. As reported in section III.D, many studies 
have shown that rapid sand filtration preceded by coagulation can 
achieve significant removal of Cryptosporidium (Patania et al. 1995, 
Nieminski and Ongerth 1995, Ongerth and Pecoraro 1995, LeChevallier and 
Norton 1992, LeChevallier et al. 1991, Dugan et al. 2001, Nieminski and 
Bellamy 2000, McTigue et al. 1998, Patania et al. 1999, Huck et al. 
2000, Emelko et al. 2000). While these studies evaluated only a single 
stage of filtration, the same mechanisms of removal are expected to 
occur in a second stage of granular media filtration.
    EPA received data from the City of Cincinnati, OH, on the removal 
of aerobic spores through a conventional treatment facility that 
employs GAC contactors for DBP, taste, and odor control after rapid 
sand filtration. As described previously, a number of studies (Dugan et 
al. 2001, Emelko et al. 1999 and 2000, Yates et al. 1998, Mazounie et 
al. 2000) have demonstrated that aerobic spores are a conservative 
indicator of Cryptosporidium removal by granular media filtration when 
preceded by coagulation.
    During the period of 1999 and 2000, the mean values of reported 
spore concentrations in the influent and effluent of the Cincinnati GAC 
contactors were 35.7 and 6.4 cfu/100 mL, respectively, indicating an 
average removal of 0.75 log across the contactors. Approximately 16% of 
the GAC filtered water results were below detection limit (1 cfu/100 
mL) so the actual log spore removal may have been greater than 
indicated by these results.
    In summary, studies in the cited literature demonstrate that a fine 
granular media filter preceded by coagulation can achieve high levels 
of Cryptosporidium removal. Data on increased removal resulting from a 
second stage of filtration are limited, and there is uncertainty 
regarding how effective a second stage of filtration will be in 
reducing levels of microbial pathogens that are not removed by the 
first stage of filtration. However, EPA has concluded that a secondary 
filtration process can achieve 0.5 log or greater removal of 
Cryptosporidium based on (1) the theoretical consideration that the 
same mechanisms of pathogen removal will be operative in both a primary 
and secondary filtration stage, and (2) data from the City of 
Cincinnati showing aerobic spore removal in GAC contactors following 
rapid sand filtration. Therefore, EPA believes it is appropriate to 
propose 0.5 log additional Cryptosporidium treatment credit for systems 
using secondary filtration which meets the criteria of this section.
    c. Request for comment. The Agency requests comment on awarding a 
0.5 log Cryptosporidium removal credit for systems using secondary 
filtration, including the design and operational criteria required to 
receive the log removal credit. EPA specifically requests comment on 
the following issues:
    [sbull] Should there be a minimum required depth for the secondary 
filter (e.g., 24 inches) in order for the system to receive credit?
    [sbull] Should systems be eligible to receive additional 
Cryptosporidium treatment credit within the microbial toolbox for both 
a second clarification stage (e.g., secondary filtration, second stage 
sedimentation) and lower finished water turbidity, given that 
additional particle removal achieved by the second clarification stage 
will reduce finished water turbidity?
14. Ozone and Chlorine Dioxide
    a. What is EPA proposing today? Similar to the methodology used for 
estimating log inactivation of Giardia lamblia by various chemical 
disinfectants in 40 CFR 141.74, EPA is proposing the CT concept for 
estimating log inactivation of Cryptosporidium by chlorine dioxide or 
ozone. In today's proposal, systems must determine the total 
inactivation of Cryptosporidium each day the system is in operation, 
based on the CT values in Table IV-19 for ozone and Table IV-20 for 
chlorine dioxide. The parameters necessary to determine the total 
inactivation of Cryptosporidium must be monitored as stated in 40 CFR 
141.74(b)(3)(i), (iii), and (iv), which is as follows:
    [sbull] The temperature of the disinfected water must be measured 
at least once per day at each residual disinfectant concentration 
sampling point.
    [sbull] The disinfectant contact time(s) (``T'') must be determined 
for each day during peak hourly flow.
    [sbull] The residual disinfectant concentration(s) (``C'') of the 
water before or at the first customer must be measured each day during 
peak hourly flow.
    Systems may have several disinfection segments (the segment is 
defined as a treatment unit process with a measurable disinfectant 
residual level and a liquid volume) in sequence along the treatment 
train. In determining the total log inactivation, the system may 
calculate the log inactivation for each disinfection segment and use 
the sum of the log inactivation estimates of Cryptosporidium achieved 
through the

[[Page 47710]]

plant. The Toolbox Guidance Manual, available in draft with today's 
proposal, provides guidance on methodologies for determining CT values 
and estimating log inactivation for different disinfection reactor 
designs and operations.

                                            Table IV-19.--CT Values for Cryptosporidium Inactivation by Ozone
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                              Water Temperature, [deg]C \1\
                          Log credit                           -----------------------------------------------------------------------------------------
                                                                 <=0.5      1        2        3        5        7        10       15       20       25
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.5...........................................................       12       12       10      9.5      7.9      6.5      4.9      3.1      2.0      1.2
1.0...........................................................       24       23       21       19       16       13      9.9      6.2      3.9      2.5
1.5...........................................................       36       35       31       29       24       20       15      9.3      5.9      3.7
2.0...........................................................       48       46       42       38       32       26       20       12      7.8      4.9
2.5...........................................................       60       58       52       48       40       33       25       16      9.8      6.2
3.0...........................................................       72       69       63       57       47       39       30       19       12     7.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ CT values between the indicated temperatures may be determined by interpolation.


                                      Table IV-20.--CT Values for Cryptosporidium Inactivation by Chlorine Dioxide
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                              Water Temperature, [deg]C \1\
                          Log credit                           -----------------------------------------------------------------------------------------
                                                                 <=0.5      1        2        3        5        7        10       15       20       25
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.5...........................................................      319      305      279      256      214      180      138       89       58       38
1.0...........................................................      637      610      558      511      429      360      277      179      116       75
1.5...........................................................      956      915      838      767      643      539      415      268      174      113
2.0...........................................................     1275     1220     1117     1023      858      719      553      357      232      150
2.5...........................................................     1594     1525     1396     1278     1072      899      691      447      289      188
3.0...........................................................     1912     1830     1675     1534     1286     1079      830      536      347     226
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ CT values between the indicated temperatures may be determined by interpolation.

    The system may demonstrate to the State, through the use of a 
State-approved protocol for on-site disinfection challenge studies or 
other information satisfactory to the State, that CT values other than 
those specified in Tables IV-19 or IV-20 are adequate to demonstrate 
that the system is achieving the required log inactivation of 
Cryptosporidium. Protocols for making such demonstrations are available 
in the Toolbox Guidance Manual.
    b. How was this proposal developed? EPA relied in part on analyses 
by Clark et al. (2002a and 2002b) to develop the CT values for ozone 
and chlorine dioxide inactivation of Cryptosporidium in today's 
proposal. Clark et al. (2002a) used data from studies of ozone 
inactivation of Cryptosporidium in laboratory water to develop 
predictive equations for estimating inactivation (Rennecker et al. 
1999, Li et al. 2001) and data from studies in natural water to 
validate the equations (Owens et al. 2000, Oppenheimer et al. 2000). 
For chlorine dioxide, Clark et al. (2002b) employed data from Li et al. 
(2001) to develop equations for predicting inactivation, and used data 
from Owens et al. (1999) and Ruffell et al. (2000) to validate the 
equations.
    Another step in developing the CT values for Cryptosporidium 
inactivation in today's proposal involved consideration of the 
appropriate confidence bound to apply when analyzing the inactivation 
data. A confidence bound represents a safety margin that accounts for 
variability and uncertainty in the data that underlie the analysis. 
Confidence bounds are intended to provide a high likelihood that 
systems operating at a given CT value will achieve at least the 
corresponding log inactivation level in the CT table.
    Two types of confidence bounds that are used when assessing 
relationships between variables, such as disinfectant dose (CT) and log 
inactivation, are confidence in the regression and confidence in the 
prediction. Confidence in the regression accounts for uncertainty in 
the regression line (e.g., a linear relationship between temperature 
and the log of the ratio of CT to log inactivation). Confidence in the 
prediction accounts for both uncertainty in the regression line and 
variability in experimental observations--it describes the likelihood 
of a single future data point falling within a range. Bounds for 
confidence in prediction are wider (i.e., more conservative) than those 
for confidence in the regression. Depending on the degree of confidence 
applied, most points in a data set typically will fall within the 
bounds for confidence in the prediction, while a significant fraction 
will fall outside the bounds for confidence in the regression.
    In developing earlier CT tables, EPA has used bounds for confidence 
in the prediction. This was a conservative approach that was taken with 
consideration of the limited inactivation data that were available and 
that reasonably ensured systems would achieve the required inactivation 
level. The November 2001 draft of the LT2ESWTR included CT tables for 
Cryptosporidium inactivation by ozone and chlorine dioxide that were 
derived using confidence in prediction (USEPA 2001g). However, based on 
comments received on those draft tables, along with further analyses 
described next, EPA has revised this approach in today's proposal.
    The underlying Cryptosporidium inactivation data used to develop 
the CT tables exhibit significant variability. This variability is due 
to both experimental error and potential true variability in the 
inactivation rate. Experimental error is associated with the assays 
used to measure loss of infectivity, measurement of the disinfectant 
concentration, differences in technique among researchers, and other 
factors. True variability in the inactivation rate would be associated 
with variability in resistance to the disinfectant between different 
populations of oocysts and variability in the effect of water matrix on 
the inactivation process.

[[Page 47711]]

    In considering the appropriate confidence bounds to use for 
developing the CT tables in today's proposal, EPA was primarily 
concerned with accounting for uncertainty in the regression and for 
true variability in the inactivation rate. Variability associated with 
experimental error was a lessor concern, as the purpose of the CT 
tables is to ensure a given level of inactivation and not predict the 
measured result of an individual experiment.
    Because confidence in the prediction accounts for all variability 
in the data sets (both true variability and experimental error), it may 
provide a higher margin of safety than is necessary. Nevertheless, in 
other disinfection applications, the use of confidence in the 
prediction may be appropriate, given limited data sets and uncertainty 
in the source of the variability. However, the high doses of ozone and 
chlorine dioxide that are needed to inactivate Cryptosporidium create 
an offsetting concern with the formation of DBPs (e.g., bromate and 
chlorite). In consideration of these factors and the statutory 
provision for balancing risks among contaminants, EPA attempted to 
exclude experimental error from the confidence bound when developing 
the CT tables in today's proposal (i.e., used a less conservative 
approach than confidence in the prediction).
    In order to select confidence bounds reflecting potential true 
variability between different oocyst populations (lots) but not 
variability due to measurement and experimental imprecision, it was 
necessary to estimate the relative contributions of these variance 
components. This was done by first separating inactivation data points 
into groups having the same Cryptosporidium oocyst lot and experimental 
conditions (e.g., water matrix, pH, temperature). Next, the variance 
within each group was determined. It was assumed that this within-group 
variance could be attributed entirely to experimental error, as neither 
of the factors expected to account for true variability in the 
inactivation rate (i.e., oocyst lot or water matrix) changed within a 
group. Finally, comparing the average within-group variance to the 
total variance in a data set provided an indication of the fraction of 
total variance that was due to experimental error (see Sivaganesan 2003 
and Messner 2003 for details).
    In carrying out this analysis on the Li et al. (2001) and Rennecker 
et al. (1999) data sets for ozone inactivation of Cryptosporidium, EPA 
estimated that 87.5% of the total variance could be attributed to 
experimental error (Sivaganesan 2003). A similar analysis done by Najm 
et al. (2002) on the Oppenheimer et al. (2000) data set for ozone 
produced an estimate of 89% of the total variance due to experimental 
error. For chlorine dioxide inactivation of Cryptosporidium, EPA 
estimated that 62% of the total variance in the Li et al. (2001) and 
Ruffle et al. (1999) data sets could be attributed to experimental 
error (Messner 2003). The different fractions attributed to 
experimental error between the chlorine dioxide and ozone data sets 
presumably relates to the use of different experimental techniques 
(e.g., infectivity assays).
    EPA employed estimates of the fraction of variance not attributable 
to experimental error (12.5% for ozone and 38% for chlorine dioxide) in 
a modified form of the equation used to calculate a bound for 
confidence in prediction (Messner 2003). These were applied to the 
regression equations developed by Clark et al. (2002a and 2002b) in 
order to estimate CT values for an upper 90% confidence bound 
(Sivaganesan 2003, Messner 2003). These are the CT values shown in 
Tables IV-19 and IV-20 for ozone and chlorine dioxide, respectively.
    Since the available data are not sufficient to support the CT 
calculation for an inactivation level greater than 3 log, the use of 
Tables IV-19 and IV-20 is limited to inactivation less than or equal to 
3 log. In addition, the temperature limitation for these tables is 1 to 
25 [deg]C. If the water temperature is higher than 25 [deg]C, 
temperature should be set to 25 [deg]C for the log inactivation 
calculation.
    EPA recognizes that inactivation rates may be sensitive to water 
quality and operational conditions in the plant. To reflect this 
potential, systems are given the option to perform a site specific 
inactivation study to determine CT requirements. The State must approve 
the protocols or other information used to derive alternative CT 
values. However, EPA has provided guidance for systems in making such 
demonstrations in the Toolbox Guidance Manual.
    During meetings of the Stage 2 M-DBP Advisory Committee, CT values 
were used in the model for impact analysis of different regulatory 
options (the model Surface Water Analytical Tool (SWAT), as described 
in Economic Analysis for the LT2ESWTR, USEPA 2003a). Those preliminary 
CT values were based on a subset of the data from the Li et al. (2001) 
study with laboratory waters and were adjusted with a factor to match 
the mean CT values derived from the Oppenheimer et al. (2000) study 
with natural waters. In comparison, the CT values in today's proposal 
are higher. However, the current CT values are based on larger data 
sets and more comprehensive analyses. Consequently, they provide more 
confidence in estimates of Cryptosporidium log inactivation than the 
preliminary estimates used in earlier SWAT modeling. EPA has 
subsequently re-run analyses for LT2ESWTR impact assessments with the 
updated CT values (USEPA 2003a).
    c. Request for comments. EPA requests comment on the proposed 
approach to awarding credit for inactivation of Cryptosporidium by 
chlorine dioxide and ozone, including the following specific issues:
    [sbull] Determination of CT and the confidence bounds used for 
estimating log inactivation of Cryptosporidium;
    [sbull] The ability of systems to apply these CT tables in 
consideration of the MCLs for bromate and chlorite; and
    [sbull] Any additional data that may be used to confirm or refine 
the proposed CT tables.
15. Ultraviolet Light
    a. What is EPA proposing today? EPA is proposing criteria for 
awarding credit to ultraviolet (UV) disinfection processes for 
inactivation of Cryptosporidium, Giardia lamblia, and viruses. The 
inactivation credit a system can receive for each target pathogen is 
based on the UV dose applied by the system in relation to the UV dose 
requirements in this section (see Table IV-21).
    To receive UV disinfection credit, a system must demonstrate a UV 
dose using the results of a UV reactor validation test and ongoing 
monitoring. The reactor validation test establishes the operating 
conditions under which a reactor can deliver a required UV dose. 
Monitoring is used to demonstrate that the system maintains these 
validated operating conditions during routine use.
    UV dose (fluence) is defined as the product of the UV intensity 
over a surface area (fluence rate) and the exposure time. In practice, 
UV reactors deliver a distribution of doses due to variation in light 
intensity and flow path as particles pass through the reactor. However, 
for the purpose of determining compliance with the dose requirements in 
Table IV-21, UV dose must be assigned to a reactor based on the degree 
of inactivation of a microorganism achieved during a reactor validation 
test. This assigned UV dose is determined through comparing the reactor 
validation test results with a known dose-response relationship for the 
test microorganism. The State may

[[Page 47712]]

designate an alternative basis for awarding UV disinfection credit.
    EPA is developing the UV Disinfection Guidance Manual (USEPA 2003d) 
to assist systems and States with implementing UV disinfection, 
including validation testing of UV reactors. This guidance is available 
in draft in the docket for today's proposal (http://www.epa.gov/edocket/).
UV Dose Tables
    Table IV-21 shows the UV doses that systems must apply to receive 
credit for up to 3 log inactivation of Cryptosporidium and Giardia 
lamblia and up to 4 log inactivation of viruses. These dose values are 
for UV light at a wavelength of 254 nm as delivered by a low pressure 
mercury vapor lamp. However, the dose values can be applied to other UV 
lamp types (e.g., medium pressure mercury vapor lamps) through reactor 
validation testing, such as is described in the draft UV Disinfection 
Guidance Manual (USEPA 2003d). In addition, the dose values in Table 
IV-21 are intended for post-filter application of UV in filtration 
plants and for systems that meet the filtration avoidance criteria in 
40 CFR 141.71.
BILLING CODE 6560-50-P
[GRAPHIC] [TIFF OMITTED] TP11AU03.011

BILLING CODE 6560-50-C
Reactor Validation Testing
    For a system to receive UV disinfection credit, the UV reactor type 
used by the system must undergo validation testing to demonstrate the 
operating conditions under which the reactor can deliver the required 
UV dose. Unless the State approves an alternative approach, this 
testing must involve the following: (1) Full scale testing of a reactor 
that conforms uniformly to the UV reactors used by the system and (2) 
inactivation of a test microorganism whose dose response 
characteristics have been quantified with a low pressure mercury vapor 
lamp.
    Validation testing must determine a set of operating conditions 
that can be monitored by the system to ensure that the required UV dose 
is delivered under the range of operating conditions applicable to the 
system. At a minimum, these operating conditions must include flow 
rate, UV intensity as measured by a UV sensor, and UV lamp status. The 
validated operating conditions determined by testing must account for 
the following factors: (1) UV absorbance of the water, (2) lamp fouling 
and aging, (3) measurement uncertainty of on-line sensors, (4) dose 
distributions arising from the velocity profiles through the reactor, 
(5) failure of UV lamps or other critical system components, and (6) 
inlet and outlet piping or channel configurations of the UV reactor. In 
the draft UV Disinfection Guidance Manual (USEPA 2003d), EPA describes 
testing protocols for reactor validation that are intended to meet 
these criteria.
Reactor Monitoring
    Systems must monitor for parameters necessary to demonstrate 
compliance with the operating conditions that were validated for the 
required UV dose. At a minimum systems must monitor for UV intensity as 
measured by a UV sensor, flow rate, and lamp outage. As part of this, 
systems must check the calibration of UV sensors and recalibrate in 
accordance with a protocol approved by the State.
    b. How was this proposal developed? UV disinfection is a physical 
process relying on the transference of electromagnetic energy from a 
source (lamp) to an organism's cellular material (USEPA 1986). In the 
Stage 2 M-DBP Agreement in Principle, the Advisory Committee 
recommended that EPA determine the UV doses needed to achieve up to 3 
log inactivation of Giardia lamblia and Cryptosporidium and up to 4 log 
inactivation of viruses.
    The Agreement further recommends that EPA develop standards to 
determine if UV systems are acceptable for compliance with drinking 
water disinfection requirements, including (1) a validation protocol 
for drinking water applications of UV technology and (2) on-site 
monitoring requirements to ensure ongoing compliance with UV dose 
tables. EPA also agreed to develop a UV guidance manual to facilitate 
design and operation of UV installations. Today's proposal and

[[Page 47713]]

accompanying guidance for UV are consistent with the Agreement.
UV Dose Tables
    The UV dose values in Table IV-21 are based on meta-analyses of UV 
inactivation studies with Cryptosporidium parvum, Giardia lamblia, 
Giardia muris, and adenovirus (Qian et al. 2003, USEPA 2003d). Proposed 
UV doses for inactivation of viruses are based on the dose-response of 
adenovirus because, among viruses that have been studied, it appears to 
be the most UV resistant and is a widespread waterborne pathogen 
(health effects of adenovirus are described in Embrey 1999).
    The data supporting the dose values in Table IV-21 are from bench-
scale studies using low pressure mercury vapor lamps. These data were 
chosen because the experimental conditions allow UV dose to be 
accurately quantified. Low pressure lamps emit light primarily at a 
single wavelength (254 nm) within the germicidal range of 200-300 nm. 
However, as noted earlier, these dose tables can be applied to reactors 
with other lamp types through reactor challenge testing, as described 
in the draft guidance manual. Bench scale studies are preferable for 
determining pathogen dose-response characteristics, due to the uniform 
dose distribution.
    The data sets and statistical evaluation that were used to develop 
the UV dose table for Cryptosporidium, Giardia lamblia, and viruses are 
described in the draft UV Disinfection Guidance Manual (USEPA 2003d) 
and Qian et al. 2003.
Reactor Validation Testing
    Today's proposal requires testing of full-scale UV reactors because 
of the difficulty in predicting reactor disinfection performance based 
on modeled results or on the results of testing at a reduced scale. All 
flow-through UV reactors deliver a distribution of doses due to 
variation in light intensity within the reactor and the different flow 
paths of particles passing through the reactor. Moreover, the reactor 
dose distribution varies temporally due to processes like lamp aging 
and fouling, changes in UV absorbance of the water, and fluctuations in 
flow rate. Consequently, it is more reliable to evaluate reactor 
performance through a full scale test under conditions that can be 
characterized as ``worst case'' for a given application. Such 
conditions include maximum and minimum flow rate and reduced light 
intensity within the reactor that accounts for lamp aging, fouling, and 
UV absorbance of the water. Protocols for reactor validation testing 
are presented in the draft UV guidance manual.
    c. Request for comment. The Agency requests comment on whether the 
criteria described in this section for awarding treatment credit for UV 
disinfection are appropriate, and whether additional criteria, or more 
specific criteria, should be included.
16. Individual Filter Performance
    a. What is EPA proposing today? EPA is proposing an additional 1.0 
log Cryptosporidium treatment credit for systems that achieve 
individual filter performance consistent with the goals established for 
the Partnership for Safe Water Phase IV in August 2001 (AWWA et al. 
2001). Specifically, systems must demonstrate ongoing compliance with 
the following turbidity criteria, based on continuous monitoring of 
turbidity for each individual filter as required under 40 CFR 141.174 
or 141.560, as applicable:

    (1) Filtered water turbidity less than 0.1 NTU in at least 95% 
of the maximum daily values recorded at each filter in each month, 
excluding the 15 minute period following backwashes, and
    (2) No individual filter with a measured turbidity level of 
greater than 0.3 NTU in two consecutive measurements taken 15 
minutes apart.

    Note that today's proposal does not include a required peer review 
step as a condition for receiving additional credit. Rather, EPA is 
proposing to award additional credit to systems that meet the 
performance goals of a peer review program (Phase IV). Systems that 
receive the 1 log additional treatment credit for individual filter 
performance, as described in this section, cannot also receive an 
additional 0.5 log additional credit for lower finished water turbidity 
as described in section IV.C.8.
    b. How was this proposal developed? In the Stage 2 M-DBP Agreement 
in Principle, the Advisory Committee recommended a peer review program 
as a microbial toolbox component that should receive a 1.0 log 
Cryptosporidium treatment credit. The Committee specified Phase IV of 
the Partnership for Safe Water (Partnership) as an example of the type 
of peer review program where a 1.0 log credit would be appropriate.
    The Partnership is a voluntary cooperative program involving EPA, 
the Association of Metropolitan Water Agencies (AMWA), the American 
Water Works Association (AWWA), the National Association of Water 
Companies (NAWC), the Association of State Drinking Water 
Administrators (ASDWA), the American Water Works Association Research 
Foundation (AWWARF), and surface water utilities throughout the United 
States. The intent of the Partnership is to increase protection against 
microbial contaminants by optimizing treatment plant performance.
    At the time of the Advisory Committee recommendation, Phase IV was 
under development by the Partnership. It was to be based on Composite 
Correction Program (CCP) (USEPA 1991) procedures and performance goals, 
and was to be awarded based on an on-site evaluation by a third-party 
team. The performance goals for Phase IV were such that, over a year, 
each sedimentation basin and each filter would need to produce 
specified turbidity levels based on the maximum of all the values 
recorded during the day. Sedimentation performance goals were set at 
2.0 NTU if the raw water was greater than 10 NTU on an annual basis and 
1.0 NTU if the raw water was less than 10 NTU. Each filter was to meet 
0.1 NTU 95% of the time except for the 15 minute period following 
placing the filter in operation. In addition, filters were expected to 
have maximum turbidity of 0.3 NTU and return to less than 0.1 NTU 
within 15 minutes of the filter being placed in service.
    The primary purpose of the on-site evaluation was to confirm that 
the performance of the plant was consistent with Phase IV performance 
goals and that the system had the administrative support and 
operational capabilities to sustain the performance long-term. The on-
site evaluation in Phase IV also allowed utilities that could not meet 
the desired performance goals to demonstrate to the third-party that 
they had achieved the highest level of performance given their unique 
raw water quality.
    After the signing of the Stage 2 M-DBP Agreement in Principle in 
September 2000, the Partnership decided to eliminate the on-site third-
party evaluation as a component of Phase IV. Instead, the requirement 
for Phase IV is for the water system to complete an application package 
that will be reviewed by trained utility volunteers. Included in the 
application package is an Optimization Assessment Spreadsheet in which 
the system enters water quality and treatment data to demonstrate that 
Phase IV performance levels have been achieved. The application also 
requires narratives related to administrative support and operational 
capabilities to sustain performance long-term.
    Today's proposal is consistent with the performance goals of Phase 
IV.

[[Page 47714]]

Rather than require systems to complete an application package with 
historical data and narratives, the LT2ESWTR requires systems to 
demonstrate to the State that they meet the individual filter 
performance goals of Phase IV on an ongoing basis to receive the 1.0 
log additional Cryptosporidium treatment credit. EPA is not requiring 
systems to demonstrate that they meet sedimentation performance goals 
of Phase IV. While EPA recognizes that settled water turbidity is an 
important operational performance measure for a plant, the Agency does 
not have data directly relating it to finished water quality and 
pathogen risk.
    The November 2001 pre-proposal draft of the LT2ESWTR described a 
potential 1.0 log credit for systems that achieved individual filter 
effluent (IFE) turbidity below 0.15 NTU in 95 percent of samples (USEPA 
2001g). The Science Advisory Board (SAB) subsequently reviewed this 
credit and supporting data on the relationship between filter effluent 
turbidity and Cryptosporidium removal efficiency (described in section 
IV.C.8). In written comments from a December 2001 meeting of the 
Drinking Water Committee, an SAB panel recommended only a 0.5 log 
credit for 95th percentile IFE turbidity below 0.15 NTU.
    To address this recommendation from the SAB, EPA is proposing that 
systems meet the individual filter performance criteria of Phase IV of 
the Partnership in order to be eligible for a 1.0 log additional 
Cryptosporidium treatment credit. This proposed approach responds to 
the concerns raised by the SAB because the Phase IV criteria are more 
stringent than those in the 2001 pre-proposal draft of the LT2ESWTR. 
For example, today's proposal sets a maximum limit on individual filter 
effluent turbidity of 0.3 NTU, whereas no such upper limit was 
described in the 2001 pre-proposal draft.
    In summary, EPA has concluded that it is appropriate to award 
additional Cryptosporidium treatment credit for systems meeting 
stringent individual filter performance standards. Modestly elevated 
turbidity from a single filter may not significantly impact combined 
filter effluent turbidity levels, which are regulated under IESWTR and 
LT1ESWTR, but may indicate a substantial reduction in the overall 
pathogen removal efficiency of the filtration process. Consequently, 
systems that continually achieve very low turbidity in each individual 
filter are likely to provide a significantly more effective microbial 
barrier. EPA expects that systems that select this toolbox option will 
have achieved a high level of treatment process optimization and 
process control, and will have both a history of consistent performance 
over a range of raw water quality conditions and the capability and 
resources to maintain this performance long-term.
    c. Request for comment. The Agency invites comment on the following 
issues related to the proposed credit for individual filter 
performance.
    [sbull] Are there different or additional performance measures that 
a utility should be required to meet for the 1 log additional credit?
    [sbull] Are there existing peer review programs for which treatment 
credit should be awarded under the LT2ESWTR? If so, what role should 
primacy agencies play in establishing and managing any such peer review 
program?
    [sbull] The individual filter effluent turbidity criterion of 0.1 
NTU is proposed because it is consistent with Phase IV Partnership 
standards, as based on CCP goals. However, with allowable rounding, 
turbidity levels less than 0.15 NTU are in compliance with a standard 
of 0.1. Consequently, EPA requests comment on whether 0.15 NTU should 
be the standard for individual filter performance credit, as this would 
be consistent with the standard of 0.15 NTU that is proposed for 
combined filter performance credit in section IV.C.8.
17. Other Demonstration of Performance
    a. What is EPA proposing today? The purpose of the ``demonstration 
of performance'' toolbox component is to allow a system to demonstrate 
that a plant, or a unit process within a plant, should receive a higher 
Cryptosporidium treatment credit than is presumptively awarded under 
the LT2ESWTR. For example, as described in section IV.A, plants using 
conventional treatment receive a presumptive 3 log credit towards the 
Cryptosporidium treatment requirements in Bins 2-4 of the LT2ESWTR. 
This credit is based on a determination by EPA that conventional 
treatment plants achieve an average Cryptosporidium removal of 3 log 
when in compliance with the IESWTR or LT1ESWTR. However, EPA recognizes 
that some conventional treatment plants may achieve average 
Cryptosporidium removal efficiencies greater than 3 log. Similarly, 
some systems may achieve Cryptosporidium reductions with certain 
toolbox components that are greater than the presumptive credits 
awarded under the LT2ESWTR, as described in this section (IV.C).
    Where a system can demonstrate that a plant, or a unit process 
within a plant, achieves a Cryptosporidium reduction efficiency greater 
than the presumptive credit specified in the LT2ESWTR, it may be 
appropriate for the system to receive a higher Cryptosporidium 
treatment credit. Today's proposal does not include specific protocols 
for systems to make such a demonstration, due to the potentially 
complex and site specific nature of the testing that would be required. 
Rather, today's proposal allows a State to award a higher level of 
Cryptosporidium treatment credit to a system where the State 
determines, based on site-specific testing with a State-approved 
protocol, that a treatment plant or a unit process within a plant 
reliably achieves a higher level of Cryptosporidium removal on a 
continuing basis. Also, States may award a lower level of 
Cryptosporidium treatment credit to a system where a State determines, 
based on site specific information, that a plant or a unit process 
within a plant achieves a Cryptosporidium removal efficiency less than 
a presumptive credit specified in the LT2ESWTR.
    Systems receiving additional Cryptosporidium treatment credit 
through a demonstration of performance may be required by the State to 
report operational data on a monthly basis to establish that conditions 
under which demonstration of performance credit was awarded are 
maintained during routine operation. The Toolbox Guidance Manual (USEPA 
2003f) will describe potential approaches to demonstration of 
performance testing. This guidance is available in draft in the docket 
for today's proposal (http://www.epa.gov/edocket/).
    Note that as described in section IV.C, today's proposal allows 
treatment plants to achieve additional Cryptosporidium treatment credit 
through meeting the design and/or operational criteria of microbial 
toolbox components, such as combined and individual filter performance, 
presedimentation, bank filtration, two-stage softening, secondary 
filtration, etc. Plants that receive additional Cryptosporidium 
treatment credit through a demonstration of performance are not also 
eligible for the presumptive credit associated with microbial toolbox 
components if the additional removal due to the toolbox component is 
captured in the demonstration of performance credit. For example, if a 
plant receives a demonstration of performance credit based on removal 
of Cryptosporidium or an indicator while operating under conditions of 
lower finished water turbidity, the plant may not also receive 
additional presumptive credit for lower

[[Page 47715]]

finished water turbidity toolbox components.
    This demonstration of performance credit does not apply to the use 
of chlorine dioxide, ozone, or UV light, because today's proposal 
includes specific provisions allowing the State to modify the standards 
for awarding disinfection credit to these technologies. As described in 
section IV.C.14, States can approve site-specific CT values for 
inactivation of Cryptosporidium by chlorine dioxide and ozone; as 
described in section IV.C.15, States can approve an alternative 
approach for validating the performance of UV reactors.
    b. How was this proposal developed? The Stage 2 M-DBP Agreement in 
Principle recommends demonstration of performance as a process for 
systems to receive Cryptosporidium treatment credit higher than the 
presumptive credit for many microbial toolbox components, as well as 
credit for technologies not listed in the toolbox. EPA is aware that 
there may be plants where particular unit processes, or combinations of 
unit processes, achieve greater Cryptosporidium removal than the 
presumptive credit awarded under the LT2ESWTR. In addition, the Agency 
would like to allow for the use of Cryptosporidium treatment processes 
not addressed in the LT2ESWTR, where such processes can demonstrate a 
reliable specific log removal. Due to these factors, EPA is proposing a 
demonstration of performance component in the microbial toolbox, 
consistent with the Advisory Committee recommendation.
    The Agreement in Principle makes no recommendations for how a 
demonstration of performance should be conducted. It is generally not 
practical for systems to directly quantify high log removal of 
Cryptosporidium in treatment plants because of the relatively low 
occurrence of Cryptosporidium in many raw water sources and limitations 
with analytical methods. Consequently, if systems are to demonstrate 
the performance of full scale plants in removing Cryptosporidium, this 
typically will require the use of indicators, where the removal of the 
indicator has been correlated with the removal of Cryptosporidium. As 
described previously, a number of studies have shown that aerobic 
spores are an indicator of Cryptosporidium removal by sedimentation and 
filtration (Dugan et al. 2001, Emelko et al. 1999 and 2000, Yates et 
al. 1998, Mazounie et al. 2000).
    The nature of demonstration of performance testing that will be 
appropriate at a given facility will depend on site specific factors, 
such as water quality, the particular process(es) being evaluated, 
resources and infrastructure, and the discretion of the State. 
Consequently, EPA is not proposing specific criteria for demonstration 
of performance testing. Instead, systems must develop a testing 
protocol that is approved by the State, including any requirements for 
ongoing reporting if demonstration of performance credit is approved. 
EPA has developed a draft document, Toolbox Guidance Manual (USEPA 
2003f), that is available with today's proposal and provides guidance 
on demonstration of performance testing.
    c. Request for comment. The Agency requests comment on today's 
proposal for systems to demonstrate higher Cryptosporidium removal 
levels. EPA specifically requests comment on the following issues:
    [sbull] Approaches that should be considered or excluded for 
demonstration of performance testing;
    [sbull] Whether EPA should propose minimum elements that 
demonstration of performance testing must include;
    [sbull] Whether a factor of safety should be applied to the results 
of demonstration of performance testing to account for potential 
differences in removal of an indicator and removal of Cryptosporidium, 
or uncertainty in the application of pilot-scale results to full-scale 
plants;
    [sbull] Whether or under what conditions a demonstration of 
performance credit should be allowed for a unit process within a 
plant--a potential concern is that certain unit processes, such as a 
sedimentation basin, can be operated in a manner that will increase 
removal in the unit process but decrease removal in subsequent 
treatment processes and, therefore, lead to no overall increase in 
removal through the plant. An approach to address this concern is to 
limit demonstration of performance credit to removal demonstrated 
across the entire treatment plant.

D. Disinfection Benchmarks for Giardia lamblia and Viruses

1. What Is EPA Proposing Today?
    EPA proposes to establish the disinfection benchmark under the 
LT2ESWTR as a procedure to ensure that systems maintain protection 
against microbial pathogens as they implement the Stage 2 M-DBP rules 
(i.e., Stage 2 DBPR and LT2ESWTR). The disinfection benchmark serves as 
a tool for systems and States to evaluate the impact on microbial risk 
of proposed changes in disinfection practice. EPA established the 
disinfection benchmark under the IESWTR and LT1ESWTR for the Stage 1 M-
DBP rules, as recommended by the Stage 1 M-DBP Advisory Committee. 
Today's proposal extends disinfection benchmark requirements to apply 
to the Stage 2 M-DBP rules.
    Under the proposed LT2ESWTR, the disinfection benchmark procedure 
involves a system charting levels of Giardia lamblia and virus 
inactivation at least once per week over a period of at least one year. 
This creates a profile of inactivation performance that the System must 
use to determine a baseline or benchmark of inactivation against which 
proposed changes in disinfection practice can be measured. Only certain 
systems are required to develop profiles and keep them on file for 
State review during sanitary surveys. When those systems that are 
required to develop a profile plan a significant change in disinfection 
practice (defined later in this section), they must submit the profile 
and an analysis of how the proposed change will affect the current 
disinfection benchmark to the State for review.
    Systems that developed disinfection profiles under the IESWTR or 
LT1ESWTR and have not made significant changes in their disinfection 
practice or changed sources are not required to collect additional 
operational data to create disinfection profiles under the LT2ESWTR. 
Systems that produced a disinfection profile for Giardia lamblia but 
not viruses under the IESWTR or LT1ESWTR may be required to develop a 
profile for viruses under the LT2ESWTR. Where a previously developed 
Giardia lamblia profile is acceptable, systems may develop a virus 
profile using the same operational data (i.e., CT values) on which the 
Giardia lamblia profile is based. Spreadsheets developed by EPA and 
States automatically calculate Giardia lamblia and virus profiles using 
the same operational data. EPA believes that virus profiling is 
necessary because many of the disinfection processes that systems will 
select to comply with the Stage 2 DBPR and LT2ESWTR (e.g., chloramines, 
UV, MF/UF) are relatively less effective against viruses than Giardia 
lamblia in comparison to free chlorine.
    The disinfection benchmark provisions contain three major 
components: (a) Applicability requirements and schedule, (b) 
characterization of disinfection practice, and (c) State review of 
proposed changes in disinfection practice. Each of these components is 
discussed in the following paragraphs.

[[Page 47716]]

    a. Applicability and schedule. Proposed disinfection profiling and 
benchmarking requirements apply to surface water systems only. Systems 
serving only ground water are not subject to the requirements of the 
LT2ESWTR. The determination of whether a surface water system is 
required to develop a disinfection profile is based on whether DBP 
levels (TTHM or HAA5) exceed specified values, described later in this 
section, and whether a system is required to monitor for 
Cryptosporidium. These criteria trigger profiling because they identify 
systems that may be required to make treatment changes under the Stage 
2 DBPR or LT2ESWTR. Note that it is not practical to wait until a 
system has completed Cryptosporidium monitoring to identify which 
systems should prepare a disinfection profile. A completed disinfection 
profile should be available at the point when a system is classified in 
a treatment bin and must begin developing plans to comply with any 
additional treatment requirements.
    Unless the system developed a disinfection profile under the IESWTR 
or LT1ESWTR, all systems required to monitor for Cryptosporidium must 
develop Giardia lamblia and virus disinfection profiles under the 
LT2ESWTR. This includes all surface water systems except (1) systems 
that provide 5.5 log total treatment for Cryptosporidium, equivalent to 
meeting the treatment requirements of Bin 4 and (2) small systems 
(<10,000 people served) that do not exceed the E. coli trigger (see 
section IV.A for details). Systems not required to monitor for 
Cryptosporidium as a result of providing 5.5 log of treatment are not 
required to prepare disinfection profiles. However, small systems that 
do not exceed the E. coli trigger are required to prepare Giardia 
lamblia and virus disinfection profiles if one of the following 
criteria apply, based on DBP levels in their distribution systems:
    (1)* TTHM levels in the distribution system, based on samples 
collected for compliance with the Stage 1 DBPR, are at least 80% of the 
MCL (0.064 mg/L) at any Stage 1 DBPR sampling point based on a 
locational running annual average (LRAA).
    (2)* HAA5 levels in the distribution system, based on the samples 
collected for compliance with the Stage 1 DBPR, are at least 80% of the 
MCL (0.048 mg/L) at any Stage 1 DBPR sampling point based on an LRAA.

*These criteria only apply to systems that are required to comply with 
the DBP rules, i.e., community and non-transient non-community systems.
    Table IV-22 presents a summary schedule of the required deadlines 
for disinfection profiling activities, categorized by system size and 
whether a small system is required to monitor for Cryptosporidium. The 
deadlines are based on the expectation that a system should have a 
disinfection profile at the time the system is classified in a 
Cryptosporidium treatment bin under LT2ESWTR and/or has determined the 
need to make treatment changes for the Stage 2 DBPR. Systems have three 
years from this date, with a possible two year extension for capital 
improvements if granted by the State, within which to complete their 
evaluation, design, and implementation of treatment changes to meet the 
requirements of the LT2ESWTR and the Stage 2 DBPR.

            Table IV-22.--Schedule of Implementation Deadlines Related to Disinfection Profiling \1\
----------------------------------------------------------------------------------------------------------------
                                                                                 Systems serving <10,000 people
                                                                               ---------------------------------
                                                              Systems serving                    Not required to
                         Activity                           =10,000    Required to      monitor for
                                                                people \2\        monitor for    Cryptosporidium
                                                                                Cryptosporidium       2 3 6
----------------------------------------------------------------------------------------------------------------
Complete 1 year of E. coli monitoring.....................                NA                 42               42
Determine whether required to profile based on DBP levels                 NA                 NA               42
 and notify State \6\.....................................
Begin disinfection profiling\4\...........................                24                 54               42
Complete Cryptosporidium monitoring.......................                30                 60               NA
Complete disinfection profiling based on at least one                     36                 66              54
 year's data \5\..........................................
----------------------------------------------------------------------------------------------------------------
\1\ Numbers in table indicate months following promulgation of the LT2ESWTR.
\2\ Systems providing a total of 5.5 log Cryptosporidium treatment (equivalent to meeting Bin 4 treatment
  requirements) are not required to develop disinfection profiles.
\3\ Systems serving fewer than 10,000 people are not required to monitor for Cryptosporidium if mean E. coli
  levels are less than 10/100 mL for systems using lake/reservoir sources or less than 50/100 mL for systems
  using flowing stream sources.
\4\ Unless system has existing disinfection profiling data that are acceptable.
\5\ This deadline coincides with the start of the 3 year period at the end of which compliance with the LT2ESWTR
  and Stage 2 DBPR is required.
\6\ Not required to conduct profiling unless TTHM or HAA5 exceeds trigger values of 80% of MCL at any sampling
  point based on LRAA.

    As described in the next section, systems can meet profiling 
requirements under the proposed LT2ESWTR using previously collected 
data (i.e., grandfathered data). Use of grandfathered data is allowed 
if the system has not made a significant change in disinfection 
practice or changed sources since the data were collected. This will 
permit most systems that prepared a disinfection profile under the 
IESWTR or the LT1ESWTR to avoid collecting any new operational data to 
develop profiles under the LT2ESWTR.
    The locational running annual average (LRAA) of TTHM and HAA5 
levels used by small systems that do not monitor for Cryptosporidium to 
determine whether profiling is required must be based on one year of 
DBP data collected during the period following promulgation of the 
LT2ESWTR, or as determined by the State. By the date indicated in Table 
IV-22, these systems must report to the State on their DBP LRAAs and 
whether the disinfection profiling requirements apply. If either DBP 
LRAA meets the criteria specified previously, the system must begin 
disinfection profiling by the date proposed in Table IV-22.
    b. Developing the disinfection profile and benchmark. Under the 
LT2ESWTR, a disinfection profile consists of a compilation of Giardia 
lamblia and virus log inactivation levels computed at least weekly over 
a period of at least one year, as based on operational and water 
quality data (disinfectant residual concentration(s), contact time(s), 
temperature(s), and, where necessary, pH). The system may create the 
profile by conducting new weekly (or more frequent) monitoring and/or 
by using

[[Page 47717]]

grandfathered data. A system that created a Giardia lamblia 
disinfection profile under the IESWTR or LT1ESWTR may use the 
operational data collected for the Giardia lamblia profile to create a 
virus disinfection profile.
    Grandfathered data are those operational data that a system has 
previously collected at a treatment plant during the course of normal 
operation. Those systems that have all the necessary information to 
determine profiles using existing operational data collected prior to 
the date when the system is required to begin profiling may use these 
data in developing profiles. However, grandfathered data must be 
substantially equivalent to operational data that would be collected 
under this rule. These data must be representative of inactivation 
through the entire treatment plant and not just of certain treatment 
segments.
    To develop disinfection profiles under this rule, systems are 
required to exercise one of the following three options:
    Option 1--Systems conduct monitoring at least once per week 
following the process described later in this section.
    Option 2--Systems that conduct monitoring under this rule, as 
described under Option 1, can also use one or two years of acceptable 
grandfathered data, in addition to one year of new operational data, in 
developing the disinfection profile.
    Option 3--Systems that have at least one year of acceptable 
existing operational data are not required to conduct new monitoring to 
develop the disinfection profile under this rule. Instead, they can use 
a disinfection profile based on one to three years of grandfathered 
data.
    Process to be followed by PWS for developing the disinfection 
profile:

--Measure disinfectant residual concentration (C, in mg/L) before or at 
the first customer and just prior to each additional point of 
disinfectant addition, whether with the same or a different 
disinfectant.
--Determine contact time (T, in minutes) for each residual disinfectant 
monitoring point during peak flow conditions. T could be based on 
either a tracer study or assumptions based on contactor basin geometry 
and baffling. However, systems must use the same method for both 
grandfathered data and new data.
--Measure water temperature ([deg]C) (for disinfectants other than UV).
--Measure pH (for chlorine only).

    To determine the weekly log inactivation, the system must convert 
operational data from one day each week to the corresponding log 
inactivation values for Giardia lamblia and viruses. The procedure for 
Giardia lamblia is as follows:

--Determine CTcalc for each disinfection segment.
--Determine CT99.9 (i.e., 3 log inactivation) from tables in 
the SWTR (40 CFR 141.74) using temperature (and pH for chlorine) for 
each disinfection segment. States can allow an alternate calculation 
procedure (e.g., use of a spreadsheet).
--For each segment, log inactivation = (CTcalc/
CT99.9) x 3.0.
--Sum the log inactivation values for each segment to get the log 
inactivation for the day (or week).

    For calculating the virus log inactivation, systems should use the 
procedures approved by States under the IESWTR or LT1ESWTR. Log 
inactivation benchmark is calculated as follows:

--Determine the calendar month with the lowest log inactivation.
--The lowest month becomes the critical period for that year.
--If acceptable data from multiple years are available, the average of 
critical periods for each year becomes the benchmark.
--If only one year of data is available, the critical period for that 
year is the benchmark.

    c. State review. If a system that is required to produce a 
disinfection profile proposes to make a significant change in 
disinfection practice, it must calculate Giardia lamblia and virus 
inactivation benchmarks and must notify the State before implementing 
such a change. Significant changes in disinfection practice are defined 
as (1) moving the point of disinfection (this is not intended to 
include routine seasonal changes already approved by the State), (2) 
changing the type of disinfectant, (3) changing the disinfection 
process, or (4) making other modifications designated as significant by 
the State. When notifying the State, the system must provide a 
description of the proposed change, the disinfection profiles and 
inactivation benchmarks for Giardia lamblia and viruses, and an 
analysis of how the proposed change will affect the current 
inactivation benchmarks. In addition, the system should have 
disinfection profiles and, if applicable, inactivation benchmarking 
documentation, available for the State to review as part of its 
periodic sanitary survey.
    EPA developed for the IESWTR, with stakeholder input, the 
Disinfection Profiling and Benchmarking Guidance Manual (USEPA 1999d). 
This manual provides guidance to systems and States on the development 
of disinfection profiles, identification and evaluation of significant 
changes in disinfection practices, and considerations for setting an 
alternative benchmark. If necessary, EPA will produce an addendum to 
reflect changes in the profiling and benchmarking requirements 
necessary to comply with LT2ESWTR.
2. How Was This Proposal Developed?
    A fundamental premise in the development of the M-DBP rules is the 
concept of balancing risks between DBPs and microbial pathogens. 
Disinfection profiling and benchmarking were established under the 
IESWTR and LT1ESWTR, based on a recommendation by the Stage 1 M-DBP 
Federal Advisory Committee, to ensure that systems maintained adequate 
control of pathogen risk as they reduced risk from DBPs. Today's 
proposal would extend disinfection benchmarking requirements to the 
LT2ESWTR.
    EPA believes this extension is necessary because some systems will 
make significant changes in their current disinfection practice to meet 
more stringent limits on TTHM and HAA5 levels under the Stage 2 DBPR 
and additional Cryptosporidium treatment requirements under the 
LT2ESWTR. In order to ensure that these systems continue to provide 
adequate protection against the full spectrum of microbial pathogens, 
it is appropriate for systems and States to evaluate the effects of 
such treatment changes on microbial drinking water quality. The 
disinfection benchmark serves as a tool for making such evaluations.
    EPA projects that to comply with the Stage 2 DBPR, systems will 
make changes to their disinfection practice, including switching from 
free chlorine to chloramines and, to a lesser extent, installing 
technologies like ozone, membranes, and UV. Similarly, to provide 
additional treatment for Cryptosporidium, some systems will install 
technologies like UV, ozone, and microfiltration. While these processes 
are all effective disinfectants, chloramines are a weaker disinfectant 
than free chlorine for Giardia lamblia. Ozone, UV, and membranes can 
provide highly effective treatment for Giardia lamblia, but they, as 
well as chloramines, are less efficient for treating viruses than free 
chlorine, relative to their efficacy for Giardia lamblia. Because of 
this, a system switching from free chlorine to one of these alternative 
disinfection

[[Page 47718]]

technologies could experience a reduction in the level of virus and/or 
Giardia lamblia (for chloramines) treatment it is achieving. 
Consequently, EPA believes that systems making significant changes in 
their disinfection practice under the Stage 2 M-DBP rules should assess 
the impact of these changes with disinfection benchmarks for Giardia 
lamblia and viruses.
    Changes in the proposed benchmarking requirements under the 
LT2ESWTR in comparison to IESWTR requirements include decreasing the 
frequency of calculating CT values for the disinfection profile from 
daily to weekly and requiring all systems to prepare a profile for 
viruses as well as Giardia lamblia. The proposal of a weekly frequency 
for CT calculations was made to accommodate existing profiles from 
small systems, which are required to make weekly CT calculations for 
profiling under the LT1ESWTR. As described earlier, EPA would like for 
systems that have prepared a disinfection profile under the IESWTR or 
LT1ESWTR and have not subsequently made significant changes in 
disinfection practice to be able to grandfather this profile for the 
LT2ESWTR. Allowing weekly calculation of CT values under the LT2ESWTR 
will make this possible.
    The IESWTR and LT1ESWTR required virus inactivation profiling only 
for systems using ozone or chloramine as their primary disinfectant. 
However, as noted earlier, EPA has projected that under the Stage 2 
DBPR and LT2ESWTR, systems will switch from free chlorine to 
disinfection processes like chloramines, UV, ozone, and 
microfiltration. The efficiency of these processes for virus treatment 
relative to protozoa treatment is lower in comparison to free chlorine. 
As a result, a disinfection benchmark for Giardia lamblia would not 
necessarily provide an indication of the level or adequacy of treatment 
for viruses. Consequently, EPA believes it is appropriate for systems 
to develop profiles for both Giardia lamblia and viruses. Moreover, 
developing a profile for viruses involves a minimal increase in effort 
and no additional data collection for those systems that have 
disinfection profiles for Giardia lamblia. Systems will use the same 
calculated CT values for viruses as would be used for the Giardia 
lamblia profile.
    The strategy of disinfection profiling and benchmarking stemmed 
from data provided to the Stage1 M-DBP Advisory Committee, in which the 
baseline of microbial inactivation (expressed as logs of Giardia 
lamblia inactivation) demonstrated high variability. Inactivation 
varied by several logs (i.e., orders of magnitude) on a day-to-day 
basis at particular treatment plants and by as much as tens of logs 
over a year due to changes in water temperature, flow rate, seasonal 
changes, pH, and disinfectant demand. There were also differences 
between years at individual plants. To address these variations, M-DBP 
stakeholders developed the procedure of profiling a plant's 
inactivation levels over a period of at least one year, and then 
establishing a benchmark of minimum inactivation as a way to 
characterize disinfection practice.
    Benchmarking of inactivation levels, an assessment of the impact of 
proposed changes on the level of microbial inactivation of Giardia 
lamblia and viruses, and State review prior to approval of substantial 
changes in treatment are important steps in avoiding conditions that 
present an increase in microbial risk. In its assessment of the 
microbial risk associated with the proposed changes, States could 
consider site-specific knowledge of the watershed and hydrologic 
factors as well as variability, flexibility and reliability of 
treatment to ensure that treatment for both protozoan and viral 
pathogens is appropriate.
    EPA emphasizes that benchmarking is not intended to function as a 
regulatory standard. Rather, the objective of the disinfection 
benchmark is to facilitate interactions between the States and systems 
for the purpose of assessing the impact on microbial risk of proposed 
significant changes to current disinfection practices. Final decisions 
regarding levels of disinfection for Giardia lamblia and viruses beyond 
those required by the SWTR that are necessary to protect public health 
will continue to be left to the States. For this reason EPA has not 
mandated specific evaluation protocols or decision matrices for 
analyzing changes in disinfection practice. EPA, however, will provide 
support to the States in making these analyses through the issuance of 
guidance.
3. Request for Comments
    EPA requests comment on the proposed provisions of the inactivation 
profiling and benchmarking requirement.

E. Additional Treatment Technique Requirements for Systems With 
Uncovered Finished Water Storage Facilities

1. What Is EPA Proposing Today?
    EPA is proposing requirements for systems with uncovered finished 
water storage facilities. The proposed rule requires that systems with 
uncovered finished water storage facilities must (1) cover the 
uncovered finished water storage facility, or (2) treat storage 
facility discharge to the distribution system to achieve a 4 log virus 
inactivation, unless (3) the system implements a State-approved risk 
mitigation plan that addresses physical access and site security, 
surface water runoff, animal and bird waste, and ongoing water quality 
assessment, and includes a schedule for plan implementation. Where 
applicable, the plans should account for cultural uses by Indian 
Tribes.
    Systems must notify the State if they use uncovered finished water 
storage facilities no later than 2 years following LT2ESWTR 
promulgation. Systems must cover or treat uncovered finished facilities 
or have a State-approved risk mitigation plan within 3 years following 
LT2ESWTR promulgation, with the possibility of a two year extension 
granted by States for systems making capital improvements. Systems 
seeking approval for a risk mitigation plan must submit the plan to the 
State within 2 years following LT2ESWTR promulgation.
    These provisions apply to uncovered tanks, reservoirs, or other 
facilities where water is stored after it has undergone treatment to 
satisfy microbial treatment technique requirements for Giardia lamblia, 
Cryptosporidium, and viruses. In most cases, this refers to storage of 
water following all filtration steps, where required, and primary 
disinfection.
2. How Was This Proposal Developed?
    Today's proposal is intended to mitigate the water quality 
degradation and increased health risks that can result from uncovered 
finished water storage facilities. In addition, these proposed 
requirements for uncovered finished water storage facilities are 
consistent with recommendations of the Stage 2 M-DBP Advisory Committee 
in the Agreement in Principle (USEPA 2000a).
    The use of uncovered finished water storage facilities has been 
questioned since 1930 due to their susceptibility to contamination and 
subsequent threats to public health (LeChevallier et al. 1997). Many 
potential sources of contamination can lead to the degradation of water 
quality in uncovered finished water storage facilities. These include 
surface water runoff, algal growth, insects and fish, bird and animal 
waste, airborne deposition, and human activity.

[[Page 47719]]

    Algal blooms are the most common problem in open reservoirs and can 
become a public health risk, as they increase the presence of bacteria 
in the water. Algae growth also leads to the formation of disinfection 
byproducts and causes taste and odor problems. Some algae produce 
toxins that can induce headache, fever, diarrhea, abdominal pain, 
nausea, and vomiting. Bird and animal wastes are also common and 
significant sources of contamination. These wastes may carry microbial 
contaminants such as coliform bacteria, viruses, and human pathogens, 
including Vibrio cholera, Salmonella, Mycobacteria, Typhoid, Giardia 
lamblia, and Cryptosporidium (USEPA 1999e). Microbial pathogens are 
found in surface water runoff, along with agricultural chemicals, 
automotive wastes, turbidity, metals, and organic matter (USEPA 1999e, 
LeChevallier et al. 1997).
    In an effort to minimize contamination, systems have implemented 
various controls such as reservoir covers and liners, regular draining 
and washing, security and monitoring, bird and insect control programs, 
and drainage design to prevent surface runoff from entering the 
facility (USEPA 1999e).
    A number of studies have evaluated the degradation of water quality 
in uncovered finished water storage facilities. LeChevallier et al. 
(1997) compared influent and effluent samples from six uncovered 
finished water storage reservoirs in New Jersey for a one year period. 
There were significant increases in the turbidity, particle count, 
total coliform, fecal coliform, and heterotrophic plate count bacteria 
in the effluent relative to the influent. Of particular concern were 
fecal coliforms, which were detected in 18 percent of effluent samples 
(no influent samples were positive for coliforms). Fecal coliforms are 
used as an indicator of the potential for contamination by pathogens. 
Giardia and/or Cryptosporidium were detected in 15% of inlet samples 
and 25% of effluent samples, demonstrating a significant increase in 
the effluent. There was a significant decrease in the chlorine residual 
concentration in some effluent samples.
    Increases in algal cells, heterotrophic plate count (HPC) bacteria, 
turbidity, color, particle counts, and biomass, and decreases in 
residual chlorine levels, have been reported in other studies of 
uncovered finished water reservoirs as well (Pluntze 1974, AWWA 
Committee 1983, Silverman et al. 1983). Researchers have shown that 
small mammals, birds, fish, and algal growth contribute to the 
microbial degradation of an open finished water reservoir (Graczyk et 
al. 1996, Geldreich 1990, Fayer and Ungar 1986, Current 1986).
    As described in section II, the IESWTR and LT1ESWTR require water 
systems to cover all new reservoirs, holding tanks, or other storage 
facilities for finished water. However, these rules do not require 
systems to cover existing finished water storage facilities. EPA stated 
in the preamble to the final IESWTR (63 FR 69494, December 16, 1998) 
(USEPA 1998a) that with respect to requirements for existing uncovered 
finished water storage facilities, the Agency needed more time to 
collect and analyze additional information to evaluate regulatory 
impact. The IESWTR preamble affirmed that EPA would consider whether to 
require the covering of existing storage facilities during the 
development of subsequent microbial regulations when additional data to 
estimate national costs were available.
    Since promulgation of the IESWTR, EPA has collected sufficient data 
to estimate national cost implications of regulatory control strategies 
for uncovered finished water storage facilities. Based on information 
provided by States, EPA estimates that there are approximately 138 
uncovered finished water storage facilities in the United States and 
territories, not including reservoirs that systems currently plan to 
cover or take off-line. Costs for covering these storage facilities or 
treating the effluent, consistent with today's proposed requirements, 
are presented in section VI of this preamble and in the Economic 
Analysis for the LT2ESWTR (USEPA 2003a). Briefly, total capital costs 
were estimated as $64.4 million, resulting in annualized present value 
costs of $5.4 million at a three percent discount rate and $6.4 million 
at a seven percent discount rate.
    Based on the findings of studies cited in this section, EPA 
continues to be concerned about contamination occurring in uncovered 
finished water storage facilities. Therefore, as recommended by the 
Advisory Committee, EPA is proposing control measures for all systems 
with uncovered finished water storage facilities. This proposal is 
intended to represent a balanced approach, recognizing both the 
potentially significant but uncertain risks associated with uncovered 
finished water storage facilities and the substantial costs of either 
covering them or building alternative storage. Today's proposal allows 
systems to treat the storage facility effluent instead of providing a 
cover. Alternatively, States may determine that existing risk 
mitigation is adequate, provided a system implements a risk mitigation 
plan as described in this section.
3. Request for Comments
    EPA requests comment on the proposed requirements pertaining to 
uncovered finished water storage facilities. Specifically, the Agency 
would like comment on the following issues, and requests that comments 
include available supporting data or other technical information:
    [sbull] Is it appropriate to allow systems with uncovered finished 
water storage facilities to implement a risk management plan or treat 
the effluent to inactivate viruses instead of covering the facility?
    [sbull] If systems treat the effluent of an uncovered finished 
water storage facility instead of covering it, should systems be 
required to inactivate Cryptosporidium and Giardia lamblia, since these 
protozoa have been found to increase in uncovered storage facilities?
    [sbull] Additional information on contamination or health risks 
that may be associated with uncovered finished water storage 
facilities.
    [sbull] Additional data on how climatological conditions affect 
water quality, including daily fluctuations in the stability of the 
water related to corrosion control.
    [sbull] The definition of an uncovered finished water storage 
facility in 40 CFR 141.2 is a tank, reservoir, or other facility used 
to store water that will undergo no further treatment except residual 
disinfection and is open to the atmosphere. There is a concern that 
this definition may not include certain systems using what would 
generally be considered an uncovered finished water storage facility. 
An example is a system that applies a corrosion inhibitor compound to 
the effluent of an uncovered storage facility where water is stored 
after filtration and primary disinfection. In this case, the system may 
claim that the corrosion inhibitor constitutes additional treatment 
and, consequently, the reservoir does not meet EPA's definition of an 
uncovered finished water storage facility. EPA requests comment on 
whether the definition of an uncovered finished water storage facility 
should be revised to specifically include systems that apply a 
treatment such as corrosion control to water stored in an uncovered 
reservoir after the water has undergone filtration, where required, and 
primary disinfection.

F. Compliance Schedules

    Today's proposal includes deadlines for public water systems to 
comply with

[[Page 47720]]

the proposed monitoring, reporting, and treatment requirements. These 
deadlines stem from the microbial framework approach of the proposed 
LT2ESWTR, which involves a system-specific risk characterization 
through monitoring to determine the need for additional treatment.
1. What Is EPA Proposing Today?
    a. Source water monitoring.
    i. Filtered systems. Under today's proposal, filtered systems 
conduct source water Cryptosporidium monitoring for the purpose of 
being classified in one of four risk bins that determine the extent of 
any additional treatment requirements. Small filtered systems first 
monitor for E. coli as a screening analysis and are only required to 
monitor for Cryptosporidium if the mean E. coli level exceeds specified 
trigger values. Note that systems that currently provide or will 
provide a total of at least 5.5 log of treatment for Cryptosporidium 
are exempt from monitoring requirements.
    Large surface water systems (serving at least 10,000 people) that 
filter must sample at least monthly for Cryptosporidium, E. coli, and 
turbidity in their source water for 24 months, beginning 6 months after 
promulgation of the LT2ESWTR. Large systems must submit a sampling 
schedule to their primacy agency (in this case, EPA) no later than 3 
months after promulgation of the LT2ESWTR.
    Small surface water systems (fewer than 10,000 people served) that 
filter must conduct biweekly E. coli sampling in their source water for 
1 year, beginning 30 months after LT2ESWTR promulgation. States may 
designate an alternate indicator monitoring strategy based on EPA 
guidance, but compliance schedules will not change. Small systems that 
exceed the indicator trigger value (i.e., mean E. coli  10/
100 mL for lake/reservoir sources or  50/100 mL for flowing 
stream sources) must conduct source water Cryptosporidium sampling 
twice-per-month for 1 year, beginning 48 months after LT2ESWTR 
promulgation (i.e., beginning 6 months following the completion of E. 
coli sampling). Small systems must submit an E. coli sampling schedule 
to their primacy agency no later than 27 months after LT2ESWTR 
promulgation. If Cryptosporidium monitoring is required, small systems 
must submit a Cryptosporidium sampling schedule no later than 45 months 
after LT2ESWTR promulgation.
    Large systems must carry out a second round of source water 
monitoring beginning 108 months after LT2ESWTR promulgation, which is 6 
years after initial bin classification. Similarly, small systems must 
conduct a second round of indicator monitoring (E. coli or other as 
designated by the State) beginning 138 months after LT2ESWTR 
promulgation, which is 6 years after their initial bin classification. 
Small systems that exceed the indicator trigger value in the second 
round of indicator monitoring must conduct a second round of 
Cryptosporidium monitoring, beginning 156 months after LT2ESWTR 
promulgation.
    Compliance dates for filtered systems are summarized in Table IV-
23.

     Table IV-23.--Summary of Compliance Dates for Filtered Systems
------------------------------------------------------------------------
           System type                Requirement       Compliance date
------------------------------------------------------------------------
Large Systems (serve =10,000 people).               schedule 1,2.       months after
                                                       promulgation.
                                  Source water        Begin monthly
                                   Cryptosporidium,    monitoring 6
                                   E. coli and         months after
                                   turbidity           promulgation for
                                   monitoring.         24 months.
                                  Comply with         No later than 72
                                   additional          months after
                                   Cryptosporidium     promulgation.3
                                   treatment
                                   requirements.
                                  Second round of     Begin monthly
                                   source water        monitoring 108
                                   Cryptosporidium,    months after
                                   E. coli, and        promulgation for
                                   turbidity           24 months.
                                   monitoring 2.
Small Systems (serve <10,000      Submit E. coli      No later than 27
 people).                          sampling            months after
                                   schedule2.          promulgation.
                                  Source water E.     Begin biweekly
                                   coli monitoring.    monitoring 30
                                                       months after
                                                       promulgation for
                                                       1 year.
                                  Second round of     Begin biweekly
                                   source water E.     monitoring 138
                                   coli monitoring 2.  months after
                                                       promulgation for
                                                       1 year.
                                 ---------------------
                                    Additional requirements if indicator
                                      (e.g., E. coli) trigger level is
                                                 exceeded4
                                 ---------------------
                                  Submit              No later than 45
                                   Cryptosporidium     months after
                                   sampling schedule   promulgation.
                                   1,2.
                                  Source water        Begin twice-per-
                                   Cryptosporidium     month monitoring
                                   monitoring.         no later than 48
                                                       months after
                                                       promulgation for
                                                       1 year.
                                  Comply with         No later than 102
                                   additional          months after
                                   Cryptosporidium     promulgation.3, 5
                                   treatment
                                   requirements.
                                  Second round of     Begin twice-per-
                                   source water        month monitoring
                                   Cryptosporidium     no later than 156
                                   monitoring.         months after
                                                       promulgation for
                                                       1 year.
------------------------------------------------------------------------
\1\ Systems may be eligible to use previously collected (grandfathered)
  data to meet LT2ESWTR requirements if specified quality control
  criteria are met (described in section IV.A.1.d).
\2\ Systems are not required to monitor if they will provide at least
  5.5 log Cryptosporidium treatment and notify EPA or the State.
\3\ States may grant up to an additional two years for systems making
  capital improvements.
\4\ If the E. coli annual mean concentration exceeds 10/100 mL for
  systems using lakes/reservoir sources or exceeds 50/100 mL for systems
  using flowing stream sources, Cryptosporidium monitoring is required.
\5\ Systems that do not exceed the E. coli trigger level are classified
  in Bin 1 and are not required to provide Cryptosporidium treatment
  beyond LT1ESWTR levels.

    ii. Unfiltered systems. Surface water systems that do not filter 
and meet the criteria for avoidance of filtration (40 CFR 141.71) 
(i.e., unfiltered systems) are required to conduct source water 
Cryptosporidium monitoring to determine if their mean source water 
Cryptosporidium level exceeds 0.01 oocysts/L. There is no E. coli 
screening analysis available to small unfiltered systems. However, both 
large and small unfiltered systems conduct

[[Page 47721]]

Cryptosporidium monitoring on the same schedule as filtered systems of 
the same size. Note that unfiltered systems that currently provide or 
will provide a total of at least 3 log Cryptosporidium inactivation are 
exempt from monitoring requirements.
    Large unfiltered systems (serving at least 10,000 people) must 
conduct at least monthly Cryptosporidium sampling for 24 months, 
beginning 6 months after LT2ESWTR promulgation. Small unfiltered 
systems (serving fewer than 10,000 people) must conduct at least twice-
per-month Cryptosporidium sampling for 12 months, beginning 48 months 
after LT2ESWTR promulgation. Large systems must submit a 
Cryptosporidium sampling schedule to EPA no later than 3 months after 
LT2ESWTR promulgation, and small systems must submit a sampling 
schedule to their State no later than 45 months after LT2ESWTR 
promulgation.
    Unfiltered systems are required to conduct a second round of 
Cryptosporidium monitoring on the same schedule as filtered systems of 
the same size. Large systems must carry out a second round of 
Cryptosporidium monitoring, beginning 108 months after LT2ESWTR 
promulgation. Small systems must perform a second round of 
Cryptosporidium monitoring, beginning 156 months after LT2ESWTR 
promulgation.
    Compliance dates for unfiltered systems are summarized in Table IV-
24.

    Table IV-24.--Summary of Compliance Dates for Unfiltered Systems
------------------------------------------------------------------------
           System type                Requirement       Compliance date
------------------------------------------------------------------------
Large Systems (serve =10,000 people).               schedule \1\.       months after
                                                       promulgation.
                                  Source water        Begin monthly
                                   Cryptosporidium     monitoring [6
                                   monitoring.         months after
                                                       promulgation for
                                                       24 months.
                                  Comply with         No later than 72
                                   Cryptosporidium     months after
                                   inactivation        promulgation.\2\
                                   requirements.
                                  Second round of     Begin monthly
                                   source water        monitoring 108
                                   Cryptosporidium     months after
                                   monitoring.         promulgation for
                                                       24 months.
Small Systems (serve < 10,000     Submit sampling     No later than 45
 people).                          schedule \1\.       months after
                                                       promulgation.
                                  Source water        Begin twice-per-
                                   Cryptosporidium     month monitoring
                                   monitoring.         no later than 48
                                                       months after
                                                       promulgation for
                                                       1 year.
                                  Comply with         No later than 102
                                   Cryptosporidium     months after
                                   inactivation        promulgation.\2\
                                   requirements.
                                  Second round of     Begin twice-per-
                                   source water        month monitoring
                                   Cryptosporidium     no later than 156
                                   monitoring.         months after
                                                       promulgation for
                                                       1 year.
------------------------------------------------------------------------
\1\ Systems may be eligible to use previously collected (grandfathered)
  data to meet LT2ESWTR requirements if specified quality control
  criteria are met (described in section IV.A.1.d).
\2\ States may grant up to an additional two years for systems making
  capital improvements.

    b. Treatment requirements. Filtered systems must determine their 
bin classification and unfiltered systems must determine their mean 
source water Cryptosporidium level within 6 months of the scheduled 
month for collection of their final Cryptosporidium sample in the first 
round of monitoring. This 6 month period provides time for systems to 
receive all sample analysis results from the laboratory, analyze the 
data, and work with their primacy agency.
    Filtered systems have 3 years following initial bin classification 
to meet any additional Cryptosporidium treatment requirements. This 
equates to compliance dates of 72 months after LT2ESWTR promulgation 
for large systems and 102 months after LT2ESWTR promulgation for small 
systems (see Table IV-23). Unfiltered systems must comply with 
Cryptosporidium treatment requirements on the same schedule as filtered 
systems of the same size (see Table IV-24). The State may grant systems 
an additional two years to comply when capital investments are 
necessary, as specified in the Safe Drinking Water Act (section 
1412(b)(10)).
    Systems with uncovered finished water storage facilities are 
required to comply with the provisions described in section IV.E by 36 
months following LT2ESWTR promulgation, with the possibility of a 2 
year extension granted by the State for systems making capital 
improvements. Systems seeking approval for a risk mitigation plan must 
submit the plan to the State within 24 months following LT2ESWTR 
promulgation.
    Systems must comply with additional Cryptosporidium treatment 
requirements by implementing one or more treatment processes or control 
strategies from the microbial toolbox. Most of the toolbox components 
require submission of documentation to the State demonstrating 
compliance with design and/or implementation criteria required to 
receive credit. Compliance dates for reporting requirements associated 
with microbial toolbox components are presented in detail in section 
IV.J, Reporting and Recordkeeping Requirements.
    c. Disinfection benchmarks for Giardia lamblia and viruses. Today's 
proposed LT2ESWTR includes disinfection profiling and benchmarking 
requirements, which consist of three major components: applicability 
determination, characterization of disinfection practice, and State 
review of proposed changes in disinfection practice. Each of these 
components is discussed in detail in section IV.D. Compliance deadlines 
associated with each of these components, including associated 
reporting requirements, are stated in section IV.J, Reporting and 
Recordkeeping Requirements.
2. How Was This Proposal Developed?
    The compliance dates in today's proposal reflects the risk-targeted 
approach of the proposed LT2ESWTR, wherein additional treatment 
requirements are based on a system specific risk characterization as 
determined through source water monitoring. Additionally, they are 
designed to allow for systems to simultaneously comply with the 
LT2ESWTR and Stage 2 DBPR in order to balance risks in the control of 
microbial pathogens and DBPs. These dates are consistent with 
recommendations from the Stage 2 M-DBP Federal Advisory Committee.
    Under the LT2ESWTR, large systems will sample for Cryptosporidium 
for a period of two years in order to

[[Page 47722]]

characterize source water pathogen levels and capture a degree of 
annual variability. To expedite the date by which systems will provide 
additional treatment where high risk source waters are identified, 
large system Cryptosporidium monitoring will begin six months after 
promulgation of the LT2ESWTR. Upon completion of Cryptosporidium 
monitoring, systems will have six months to work with their primacy 
agency to determine their bin classification. Beginning at this point, 
which is three years following LT2ESWTR promulgation, large systems 
will have three years to implement the treatment processes or control 
strategies necessary to comply with any additional treatment 
requirements stemming from bin classification.
    Other large system compliance dates in areas like approval of 
grandfathered monitoring data, disinfection profiling and benchmarking, 
and reporting deadlines associated with microbial toolbox components 
all stem from the Cryptosporidium monitoring and treatment compliance 
schedule.
    With respect to small systems under the LT2ESWTR, EPA is proposing 
that small systems first monitor for E. coli as a screening analysis in 
order to reduce the number of small systems that incur the cost of 
Cryptosporidium monitoring. However, due to limitations in available 
data, the Agency has determined that it is necessary to use data 
generated by large systems under the LT2ESWTR to confirm or refine the 
E. coli indicator criteria that will trigger small system 
Cryptosporidium monitoring. Consequently, small system indicator 
monitoring will begin at the conclusion of large system monitoring. 
This approach was recommended by the Advisory Committee.
    Accordingly, small systems will monitor for E. coli for one year, 
beginning 30 months after LT2ESWTR promulgation. Following this, small 
systems will have six months to determine if they are required to 
monitor for Cryptosporidium and, if so, contract with an approved 
analytical laboratory. Cryptosporidium monitoring by small systems will 
be conducted for one year, which, when added to the one year of E. coli 
monitoring, equals two years of source water monitoring. This is 
equivalent to the time period large systems spend in source water 
monitoring.
    The time periods associated with bin assignment and compliance with 
additional treatment requirements for small systems are the same as 
those proposed for large systems. Specifically, small systems will have 
six months to work with their States to determine their bin 
classification following the conclusion of Cryptosporidium sampling. 
From this point, which is 5.5 years after LT2ESWTR promulgation, small 
systems have three years to meet any additional treatment requirements 
resulting from bin classification. States can grant additional time to 
small systems for compliance with treatment technique requirements 
through granting exemptions (see SDWA section 1416).
3. Request for Comments
    EPA requests comments on the treatment technique compliance 
schedules for large and small systems in today's proposal, including 
the following issues:
Time Window Between Large and Small System Monitoring
    Under the current proposal, small filtered system E. coli 
monitoring begins in the month following the end of large system 
Cryptosporidium, E. coli, and turbidity monitoring. EPA plans to 
evaluate large system monitoring results on an ongoing basis as the 
data are reported to determine if any refinements to the E. coli levels 
that trigger small system Cryptosporidium monitoring are necessary. If 
such refinements were deemed appropriate, EPA would issue guidance to 
States, which can establish alternative trigger values for small system 
monitoring under the LT2ESWTR.
    This implementation schedule does not leave any time between the 
end of large system monitoring and the initiation of small system 
monitoring. Consequently, if it is necessary to provide guidance on 
alternative trigger values prior to when small system monitoring 
begins, such guidance would be based on less than the full set of large 
system results (e.g., first 18 months of large system data). EPA 
requests comment on whether an additional time window between the end 
of large system monitoring and the beginning of small system monitoring 
is appropriate and, if so, how long such a window should be.
Implementation Schedule for Consecutive Systems
    The Stage 2 M-DBP Agreement in Principle (65 FR 83015, December 29, 
2000) (USEPA 2000a) continues the principle of simultaneous compliance 
to address microbial pathogens and disinfection byproducts. Systems are 
generally expected to address LT2ESTWR requirements concurrently with 
those of the Stage 2 DBPR (as noted earlier, the Stage 2 DBPR is 
scheduled to be proposed later this year and to be promulgated at the 
same time as the LT2ESWTR).
    As with the LT2ESWTR, small water systems (< 10,000 served) 
generally begin monitoring and must be in compliance with the Stage 2 
DBPR at a date later than that for large systems. However, the Advisory 
Committee recommended that small systems that buy/receive from or sell/
deliver finished water to a large system (that is, they are part of the 
same ``combined distribution system'') comply with Stage 2 DBPR 
requirements on the same schedule as the largest system in the combined 
distribution system. This approach is intended to ensure that systems 
consider impacts throughout the combined distribution system when 
making compliance decisions (e.g, selecting new technologies or making 
operational modifications) and to facilitate all systems meeting the 
compliance deadlines for the rule.
    The issue of combined distribution systems associated with systems 
buying and selling water is expected to be of less significance for the 
LT2ESWTR. The requirements of the LT2ESWTR apply to systems treating 
raw surface water and generally will not involve compliance steps when 
systems purchase treated water. Consequently, the compliance schedule 
for today's proposal does not address combined distribution systems. 
However, this proposed approach raises the possibility that a small 
system treating surface water and selling it to a large system could be 
required to take compliance steps at an earlier date under the Stage 2 
DBPR than under the LT2ESWTR. While a small system in this situation 
could choose to comply with the LT2ESWTR on an earlier schedule, the 
two rules would not require simultaneous compliance. EPA requests 
comment on how this scenario should be addressed in the LT2ESWTR.

G. Public Notice Requirements

1. What Is EPA Proposing Today?
    EPA is proposing that under the LT2ESWTR, a Tier 2 public notice 
will be required for violations of additional treatment requirements 
and a Tier 3 public notice will be required for violations of 
monitoring and testing requirements. Where systems violate LT2ESWTR 
treatment requirements, today's proposal requires the use of the 
existing health effects language for microbiological contaminant 
treatment technique violations, as stated in 40 CFR 141 Subpart Q, 
Appendix B.

[[Page 47723]]

2. How Was This Proposal Developed?
    In 2000, EPA published the Public Notification Rule (65 FR 25982, 
May 4, 2000) (USEPA 2000d), which revised the general public 
notification regulations for public water systems in order to implement 
the public notification requirements of the 1996 SDWA amendments. This 
regulation established the requirements that public water systems must 
follow regarding the form, manner, frequency, and content of a public 
notice. Public notification of violations is an integral part of the 
public health protection and consumer right-to-know provisions of the 
1996 SDWA Amendments.
    Owners and operators of public water systems are required to notify 
persons served when they fail to comply with the requirements of a 
NPDWR, have a variance or exemption from the drinking water 
regulations, or are facing other situations posing a risk to public 
health. The public notification requirements divide violations into 
three categories (Tier 1, Tier 2 and Tier 3) based on the seriousness 
of the violations, with each tier having different public notification 
requirements.
    EPA has limited its list of violations and situations routinely 
requiring a Tier 1 notice to those with a significant potential for 
serious adverse health effects from short term exposure. Tier 1 
violations contain language specified by EPA that concisely and in non-
technical terms conveys to the public the adverse health effects that 
may occur as a result of the violation. States and water utilities may 
add additional information to each notice, as deemed appropriate for 
specific situations. A State may elevate to Tier 1 other violations and 
situations with significant potential to have serious adverse health 
effects from short-term exposure, as determined by the State.
    Tier 2 public notices address other violations with potential to 
have serious adverse health effects on human health. Tier 2 notices are 
required for the following situations:
    [sbull] All violations of the MCL, maximum residual disinfectant 
level (MRDL) and treatment technique requirements, except where a Tier 
1 notice is required or where the State determines that a Tier 1 notice 
is required; and
    [sbull] Failure to comply with the terms and conditions of any 
existing variance or exemption.
    Tier 3 public notices include all other violations and situations 
requiring public notice, including the following situations:
    [sbull] A monitoring or testing procedure violation, except where a 
Tier 1 or 2 notice is already required or where the State has elevated 
the notice to Tier 1 or 2; and
    [sbull] Operation under a variance or exemption.
    The State, at its discretion, may elevate the notice requirement 
for specific monitoring or testing procedures from a Tier 3 to a Tier 2 
notice, taking into account the potential health impacts and 
persistence of the violation.
    As part of the IESWTR, EPA established health effects language for 
violations of treatment technique requirements for microbiological 
contaminants. EPA believes this language, which was developed with 
consideration of Cryptosporidium health effects, is appropriate for 
violations of additional Cryptosporidium treatment requirements under 
the LT2ESWTR.
3. Request for Comment
    EPA requests comment on whether the violations of additional 
treatment requirements for Cryptosporidium under the LT2ESWTR should 
require a Tier 2 public notice and whether the proposed health effects 
language is appropriate.

H. Variances and Exemptions

    SDWA section 1415 allows States to grant variances from national 
primary drinking water regulations under certain conditions; section 
1416 establishes the conditions under which States may grant exemptions 
to MCL or treatment technique requirements. For the reasons presented 
in the following discussion, EPA has determined that systems will not 
be eligible for variances or exemptions to the requirements of the 
LT2ESWTR.
1. Variances
    Section 1415 specifies two provisions under which general variances 
to treatment technique requirements may be granted:
    (1) A State that has primacy may grant a variance to a system from 
any requirement to use a specified treatment technique for a 
contaminant if the system demonstrates to the satisfaction of the State 
that the treatment technique is not necessary to protect public health 
because of the nature of the system's raw water source. EPA may 
prescribe monitoring and other requirements as conditions of the 
variance (section 1415(a)(1)(B)).
    (2) EPA may grant a variance from any treatment technique 
requirement upon a showing by any person that an alternative treatment 
technique not included in such requirement is at least as efficient in 
lowering the level of the contaminant (section 1415(a)(3)).
    EPA does not believe the first provision for granting a variance is 
applicable to the LT2ESWTR because Cryptosporidium treatment technique 
requirements under this rule account for the degree of source water 
contamination. Systems initially comply with the LT2ESWTR by conducting 
source water monitoring for Cryptosporidium. Filtered systems are 
required to provide additional treatment for Cryptosporidium only if 
the source water concentration exceeds a level where current treatment 
does not provide sufficient protection. All unfiltered systems are 
required to provide a baseline of 2 log inactivation of Cryptosporidium 
to achieve finished water risk levels comparable to filtered systems; 
however, unfiltered systems are required to achieve 3 log inactivation 
only if the source water level exceeds 0.01 oocysts/L.
    The second provision for granting a variance is not applicable to 
the LT2ESWTR because the treatment technique requirements of this rule 
specify the degree to which systems must lower their source water 
Cryptosporidium level (e.g., 4, 5, and 5.5 log reduction in Bins 2, 3, 
and 4, respectively). The LT2ESWTR provides broad flexibility in how 
systems achieve the required level of Cryptosporidium reduction, as 
shown in the discussion of the microbial toolbox in section VI.C 
Moreover, the microbial toolbox contains an option for Demonstration of 
Performance, under which States can award treatment credit based on the 
demonstrated efficiency of a treatment process in reducing 
Cryptosporidium levels. Thus, there is no need for this type of 
variance under the LT2ESWTR.
    SDWA section 1415(e) describes small system variances, but these 
cannot be granted for a treatment technique for a microbial 
contaminant. Hence, small system variances are not allowed for the 
LT2ESWTR.
2. Exemptions
    Under SDWA section 1416(a), a State may exempt any public water 
system from a treatment technique requirement upon a finding that (1) 
due to compelling factors (which may include economic factors such as 
qualification of the system as serving a disadvantaged community), the 
system is unable to comply with the requirement or implement measures 
to develop an alternative source of water supply; (2) the system was in 
operation on the effective date of the treatment technique requirement, 
or for a system that was not in operation by that date, no

[[Page 47724]]

reasonable alternative source of drinking water is available to the new 
system; (3) the exemption will not result in an unreasonable risk to 
health; and (4) management or restructuring changes (or both) cannot 
reasonably result in compliance with the Act or improve the quality of 
drinking water.
    If EPA or the State grants an exemption to a public water system, 
it must at the same time prescribe a schedule for compliance (including 
increments of progress or measures to develop an alternative source of 
water supply) and implementation of appropriate control measures that 
the State requires the system to meet while the exemption is in effect. 
Under section 1416(b)(2)(A), the schedule shall require compliance as 
expeditiously as practicable (to be determined by the State), but no 
later than three years after the otherwise applicable compliance date 
for the regulations established pursuant to section 1412(b)(10). For 
public water systems that do not serve more than a population of 3,300 
and that need financial assistance for the necessary improvements, EPA 
or the State may renew an exemption for one or more additional two-year 
periods, but not to exceed a total of six years.
    A public water system shall not be granted an exemption unless it 
can establish that: (1) The system cannot meet the standard without 
capital improvements that cannot be completed prior to the date 
established pursuant to section 1412(b)(10); or (2) in the case of a 
system that needs financial assistance for the necessary 
implementation, the system has entered into an agreement to obtain 
financial assistance pursuant to section 1452 or any other Federal or 
state program; or (3) the system has entered into an enforceable 
agreement to become part of a regional public water system.
    EPA believes that granting an exemption to the Cryptosporidium 
treatment requirements of the LT2ESWTR would result in an unreasonable 
risk to health. As described in section II.C, Cryptosporidium causes 
acute health effects, which may be severe in sensitive subpopulations 
and include risk of mortality. Moreover, the additional Cryptosporidium 
treatment requirements of the LT2ESWTR are targeted to systems with the 
highest degree of risk. Due to these factors, EPA is not proposing to 
allow exemptions under the LT2ESWTR.
3. Request for Comment
    a. Variances. EPA requests comment on the determination that the 
provisions for granting variances are not applicable to the proposed 
LT2ESWTR, specifically including Cryptosporidium inactivation 
requirements for unfiltered systems.
    In theory it would be possible for an unfiltered system to 
demonstrate raw water Cryptosporidium levels that were 3 log lower than 
the cutoff for bin 1 for filtered systems and, thus, that it may be 
providing comparable public health protection without additional 
inactivation. However, EPA has determined that in practice it is not 
currently economically or technologically feasible for systems to 
ascertain the level of Cryptosporidium at this concentration. This is 
due to the extremely large number and volume of samples that would be 
necessary to make this demonstration with sufficient confidence. Based 
on this determination and the Cryptosporidium occurrence data described 
in section III.C, EPA is not proposing to allow unfiltered systems to 
demonstrate raw water Cryptosporidium levels low enough to avoid 
inactivation requirements. EPA requests comment on this approach.
    b. Exemptions. EPA requests comment on the determination that 
granting an exemption to the Cryptosporidium treatment requirements of 
the LT2ESWTR would result in an unreasonable risk to health.

I. Requirements for Systems To Use Qualified Operators

    The SWTR established a requirement that each public water system 
using a surface water source or a ground water source under the direct 
influence of surface water must be operated by qualified personnel who 
meet the requirements specified by the State (40 CFR 141.70). The Stage 
1 DBPR extended this requirement to include all systems affected by 
that rule, and required that States maintain a register of qualified 
operators (40 CFR 141.130(c)). While the proposed LT2ESWTR establishes 
no new requirements regarding the operation of systems by qualified 
personnel, the Agency would like to emphasize the important role that 
qualified operators play in delivering safe drinking water to the 
public. EPA encourages States that do not already have operator 
certification programs in effect to develop such programs. States 
should also review and modify, as required, their qualification 
standards to take into account new technologies (e.g., ultraviolet 
disinfection) and new compliance requirements.

J. System Reporting and Recordkeeping Requirements

1. Overview
    Today's proposal includes reporting and recordkeeping requirements 
associated with proposed monitoring and treatment requirements. As 
described earlier, systems must conduct source water monitoring to 
determine a treatment bin classification for filtered systems or a mean 
Cryptosporidium level for unfiltered systems. Systems with previously 
collected monitoring data may be able to use (i.e., grandfather) those 
data in lieu of conducting new monitoring. Following source water 
monitoring, systems will be required to comply with any additional 
Cryptosporidium treatment requirements by implementing treatment and 
control strategies from a microbial toolbox of options. Systems must 
conduct a second round of source water monitoring six years after bin 
classification.
    In addition, systems using uncovered finished water storage 
facilities must cover the facility or provide treatment unless the 
system implements a State-approved risk management strategy. Certain 
systems will be required to conduct disinfection profiling and 
benchmarking.
    The proposed rule requires public water systems to submit schedules 
for Cryptosporidium, E. coli, and turbidity sampling at least 3 months 
before monitoring must begin. Source water sample analysis results must 
be reported not later than ten days after the end of first month 
following the month when the sample is collected. As described later, 
large systems (at least 10,000 people served) will report monitoring 
results from the initial round of monitoring directly to EPA through an 
electronic data system. Small systems will report monitoring results to 
the State. Both small and large systems will report monitoring results 
from the second round of monitoring to the State.
    Systems must report a bin classification (filtered systems) or mean 
Cryptosporidium level (unfiltered systems) within six months following 
the month when the last sample in a particular round of monitoring is 
scheduled to be collected. If systems are required to provide 
additional treatment for Cryptosporidium, they must report regarding 
the use of microbial toolbox components. Systems must notify the State 
within 24 months following promulgation of the rule if they use 
uncovered finished water storage facilities. Systems must also make 
reports related to disinfection profiling and benchmarking. Reporting

[[Page 47725]]

requirements associated with these activities are summarized in Tables 
IV-25 to IV-28.

                 Table IV-25.-- Summary of Initial Large Filtered System Reporting Requirements
----------------------------------------------------------------------------------------------------------------
        You must report the following items                           On the following schedule
----------------------------------------------------------------------------------------------------------------
Sampling schedule for Cryptosporidium, E. coli,     No later than 3 months after promulgation.
 and turbidity monitoring.
Results of Cryptosporidium, E. coli, and turbidity  No later than 10 days after the end of the first month
 analyses.                                           following the month in which the sample is collected.
Bin determination.................................  No later than 36 months after promulgation.
Demonstration of compliance with additional         Beginning 72 months after promulgation \1\ (See table IV-
 treatment requirements.                             34).
Disinfection profiling component reports..........  See Table IV-35.
----------------------------------------------------------------------------------------------------------------
\1\ States may grant an additional two years for systems making capital improvements.


                  Table IV-26.--Summary of Initial Small Filtered System Reporting Requirements
----------------------------------------------------------------------------------------------------------------
        You must report the following items                           On the following schedule
----------------------------------------------------------------------------------------------------------------
Sampling schedule for E. coli monitoring..........  No later than 27 months after promulgation.
Results of E. coli analyses (unless State approves  No later than 10 days after the end of the first month
 a different indicator).                             following the month in which the sample was collected.
Mean E. coli concentration (unless State approves   No later than 45 months after promulgation.
 a different indicator).
Disinfection profiling component reports..........  See Table IV-36.
---------------------------------------------------
                        Additional requirements if E. coli trigger level is exceeded \1\
----------------------------------------------------------------------------------------------------------------
Sampling schedule for Cryptosporidium monitoring..  No later than 45 months after promulgation.
Results of Cryptosporidium analyses...............  No later than 10 days after the end of the first month
                                                     following the month in which the sample is collected.
Bin determination.................................  No later than 66 months after promulgation.
Demonstration of compliance with additional         Beginning 102 months after promulgation \2\ (See Table IV-
 treatment requirements.                             34).
----------------------------------------------------------------------------------------------------------------
\1\ If the E. coli annual mean concentration exceeds 10/100 mL for systems using lakes/reservoirs or exceeds 50/
  100 mL for systems using flowing streams, then systems must conduct Cryptosporidium monitoring. States may
  approve alternative indicator criteria to trigger Cryptosporidium monitoring.
\2\ States may grant an additional two years for systems making capital improvements.


                 Table IV-27.--Summary of Initial Large Unfiltered System Reporting Requirements
----------------------------------------------------------------------------------------------------------------
        You must report the following items                           On the following schedule
----------------------------------------------------------------------------------------------------------------
Cryptosporidium sampling schedule.................  No later than 3 months after promulgation.
Results of Cryptosporidium analyses...............  No later than 10 days after the end of the first month
                                                     following the month in which the sample was collected.
Determination of mean Cryptosporidium               No later than 36 months after promulgation.
 concentration.
Disinfection profiling component reports..........  See Table IV-35.
Demonstration of compliance with Cryptosporidium    Beginning 72 months after promulgation \1\ (see Table IV-
 inactivation requirements.                          34).
----------------------------------------------------------------------------------------------------------------
\1\ States may grant an additional two years for systems making capital improvements.


                 Table IV-28.--Summary of Initial Small Unfiltered System Reporting Requirements
----------------------------------------------------------------------------------------------------------------
        You must report the following items                           On the following schedule
----------------------------------------------------------------------------------------------------------------
Cryptosporidium sampling schedule.................  No later than 45 months after promulgation.
Results of Cryptosporidium analyses...............  No later than 10 days after the end of the first month
                                                     following the month in which the sample was collected.
Determination of mean Cryptosporidium               No later than 66 months after promulgation.
 concentration.
Disinfection profiling component reports..........  See Table IV-35.
Demonstration of compliance with Cryptosporidium    Beginning 102 months after promulgation \1\ (see Table IV-
 inactivation requirements.                          34).
----------------------------------------------------------------------------------------------------------------
\1\ States may grant an additional two years for systems making capital improvements.


[[Page 47726]]

2. Reporting Requirements for Source Water Monitoring
    a. Data elements to be reported. Proposed reporting requirements 
for LT2ESWTR monitoring stem from proposed analytical method 
requirements. As stated in sections IV.K and IV.L, systems must have 
Cryptosporidium analyses conducted by EPA-approved laboratories using 
Methods 1622 or 1623. E. coli analyses must be performed by State-
approved laboratories using the E. coli methods proposed for approval 
in section IV.K. Systems are required to report the data elements 
specified in Table IV-29 for each Cryptosporidium analysis. To comply 
with LT2ESWTR requirements, only the sample volume filtered and the 
number of oocysts counted must be reported for samples in which at 
least 10 L is filtered and all of the sample volume is analyzed. 
Additional information is required for samples where the laboratory 
analyzes less than 10 L or less than the full sample volume collected. 
Table IV-30 presents the data elements that systems must report for E. 
coli analyses.
    As described in the following section, EPA is developing a data 
system to manage and analyze the microbial monitoring data that will be 
reported by large systems under the LT2ESWTR. EPA is exploring 
approaches for application of this data system to support small system 
data reporting as well. Systems, or laboratories acting as the systems' 
agents, must keep Method 1622/1623 bench sheets and slide examination 
report forms until 36 months after an equivalent round of source water 
monitoring has been completed (e.g., second round of Cryptosporidium 
monitoring).

                       Table IV-29.--Proposed Cryptosporidium Data Elements to be Reported
----------------------------------------------------------------------------------------------------------------
                 Data element                                       Reason for data element
----------------------------------------------------------------------------------------------------------------
Identifying information
----------------------------------------------------------------------------------------------------------------
[sbull] PWSID................................  Needed to associate plant with public water system.
[sbull] Facility ID..........................  Needed to associate sample result with facility.
[sbull] Sample collection point..............  Needed to associate sample result with sampling point.
[sbull] Sample collection date...............  Needed to determine that utilities are collecting samples at the
                                                frequency required.
[sbull] Sample type (field or matrix spike)    Needed to distinguish field samples from matrix samples for
 \1\.                                           recovery calculations.
----------------------------------------------
Sample results
----------------------------------------------------------------------------------------------------------------
[sbull] Sample volume filtered (L), to         Needed to verify compliance with sample volume requirements.
 nearest \1/4\ L \2\.
[sbull] Was 100% of filtered volume examined?  Needed to calculate the final concentration of oocysts/L and
 \3\.                                           determine if volume analyzed requirements are met.
[sbull] Number of oocysts counted............  Needed to calculate the final concentration of oocysts/L.
----------------------------------------------------------------------------------------------------------------
\1\ For matrix spike samples, sample volume spiked and estimated number of oocysts spiked must be reported.
  These data are not required for field samples.
\2\ For samples in which <10 L is filtered or <100% of the sample volume is examined, the number of filters used
  and the packed pellet volume must also be reported to verify compliance with LT2ESWTR sample volume analysis
  requirements. These data are not required for most samples.
\3\ For samples in which <100% of sample is examined, the volume of resuspended concentrate and volume of this
  resuspension processed through IMS must be reported to calculate the sample volume examined. These data will
  not be required for most samples.


                           Table IV-30.--Proposed E. coli Data Elements to be Reported
----------------------------------------------------------------------------------------------------------------
                Data element                                  Reason for collecting data element
----------------------------------------------------------------------------------------------------------------
Identifying Information
----------------------------------------------------------------------------------------------------------------
PWS ID......................................  Needed to associate analytical result with public water system.
Facility ID.................................  Needed to associate plant with public water system.
Sample collection point.....................  Needed to associate sample result with sampling point.
Sample collection date......................  Needed to determine that utilities are collecting samples at the
                                               frequency required.
Analytical method number....................  Needed to associate analytical result with analytical method.
Method Type.................................  Needed to verify that an approved method was used and call up
                                               correct web entry form.
Source water type...........................  Needed to assess Cryptosporidium indicator relationships.
E. coli/100 mL..............................  Sample result (although not required, the laboratory also will
                                               have the option of entering primary measurements for a sample
                                               into the LT2ESWTR internet-based database to have the database
                                               automatically calculate the sample result).
---------------------------------------------
Turbidity Information
----------------------------------------------------------------------------------------------------------------
Turbidity result............................  Needed to assess Cryptosporidium indicator relationships.
----------------------------------------------------------------------------------------------------------------

    b. Data system. Because source water monitoring by large systems 
(serving at least 10,000 people) will begin 6 months following 
promulgation of the LT2ESWTR, EPA expects to act as the primacy agency 
with oversight responsibility for large system sampling, analysis, and 
data reporting. To facilitate collection and analysis of large system 
monitoring data, EPA is developing an Internet-based electronic data 
collection and management system. This approach is similar to that used 
under the Unregulated Contaminants Monitoring Rule (UCMR) (64 FR 50556, 
September 17, 1999) (USEPA 1999c).
    Analytical results for Cryptosporidium, E. coli, and turbidity 
analyses will be reported directly to this database using web forms and 
software that can be downloaded free of charge.

[[Page 47727]]

The data system will perform logic checks on data entered and calculate 
final results from primary data (where necessary). This is intended to 
reduce reporting errors and limit the time involved in investigating, 
checking, and correcting errors at all levels. EPA will make large 
system monitoring data available to States when States assume primacy 
for the LT2ESWTR or earlier under State agreements with EPA.
    Large systems should instruct their laboratories to electronically 
enter monitoring results into the EPA data system using web-based 
manual entry forms or by uploading XML files from laboratory 
information management systems (LIMS). After data are submitted by a 
laboratory, systems may review the results on-line. If a system 
believes that a result was entered into the data system erroneously, 
the system may notify the laboratory to rectify the entry. In addition, 
if a system believes that a result is incorrect, the system may submit 
the result as a contested result and petition EPA or the State to 
invalidate the sample. If a system contests a sample result, the system 
must submit a rationale to the primacy agency, including a supporting 
statement from the laboratory, providing a justification. Systems may 
arrange with laboratories to review their sample results prior to the 
results being entered into the EPA data system. Also, if a system 
determines that its laboratory does not have the capability to report 
data electronically, the system can submit a request to EPA to use an 
alternate reporting format.
    Regardless of the reporting process used, systems are required to 
report an analytical monitoring result to the primacy agency no later 
than 10 days after the end of the first month following the month when 
the sample was collected. As described in section IV.A.1, if a system 
is unable to report a valid Cryptosporidium analytical result for a 
scheduled sampling date due to failure to comply with the analytical 
method requirements (e.g., violation of quality control requirements), 
the system must collect a replacement sample within 14 days of being 
notified by the laboratory or the State that a result cannot be 
reported for that date and must submit an explanation for the 
replacement sample with the analytical results. A system will not incur 
a monitoring violation if the State determines that the failure to 
report a valid analysis result was due to circumstances beyond the 
control of the system. However, in all cases the system must collect a 
replacement sample.
    The data elements to be collected by the electronic data system 
will enhance the reliability of the microbial data generated under the 
LT2ESWTR, while reducing the burden on the analytical laboratories and 
public water systems. Tables IV-31 and IV-32 summarize the system's 
data analysis functions for Cryptosporidium measurements.

                     Table IV-31.-- LT2ESWTR Data System Functions for Cryptosporidium Data
----------------------------------------------------------------------------------------------------------------
                                                                                 Applicability to sample types
        Value calculated                           Formula                   -----------------------------------
                                                                                    Field         Matrix spike
----------------------------------------------------------------------------------------------------------------
Calculation of sample volume     (Volume filtered) * (resuspended             Yes.............  Yes.
 analyzed.                        concentrate volume transferred to IMS/
                                  resuspended concentrate volume).
Pellet volume analyzed.........  (pellet volume)*(resuspended concentrated    Yes.............  Yes.
                                  volume transferred to IMS/resuspended
                                  concentrate volume).
Calculation of oocysts/L.......  (Number of oocysts counted)/(sample volume   Yes.............  Yes.
                                  analyzed).
Calculation of estimated number  (Number of oocysts spiked)/(sample volume    No..............  Yes.
 of oocysts spiked/L.             spiked).
Calculation of percent           ((Calculated  of oocysts/L for the  No..............  Yes.
 recoveries for MS samples.       MS sample)--(Calculated  of
                                  oocysts/L in the associated field sample))
                                  / (Estimated number of oocysts spiked/L) *
                                  100%.
----------------------------------------------------------------------------------------------------------------


    Table IV-32.--LT2ESWTR Data System Functions for Cryptosporidium
                            Compliance Checks
------------------------------------------------------------------------
       LT2 requirements                       Description
------------------------------------------------------------------------
Sample volume analysis.......  Specifies that the LT2 requirements for
                                sample volume analyzed were met when:
                               [sbull] volume analyzed is  10
                                L.
                               [sbull] volume analyzed is < 10 L and
                                pellet volume analyzed is at least 2 mL.
                               [sbull] volume analyzed < 10 L and pellet
                                volume analyzed < 2 mL and 100% of
                                filtered volume examined= Y and two
                                filters were used.
                               Specifies that the LT2 requirements for
                                sample volume analyzed were not met
                                when:
                               [sbull] volume analyzed < 10 L and pellet
                                volume analyzed is < 2 mL and 100% of
                                filtered volume examined= N.
                               [sbull] volume analyzed is < 10 L and
                                pellet volume analyzed < 2 mL and only 1
                                filter used.
Schedule met.................  Specifies that the predetermined sampling
                                schedule is met when the sample
                                collection data is within +/- 2 days of
                                the scheduled date.
------------------------------------------------------------------------

    c. Previously collected monitoring data. Table IV-33 provides a 
summary of the items that systems must report to EPA for consideration 
of previously collected (grandfathered) monitoring data under the 
LT2ESWTR. For each field and matrix spike (MS) sample, systems must 
report the data elements specified in Table IV-29. In addition, the 
laboratory that analyzed the samples must submit a letter certifying 
that all Method 1622 and 1623 quality control requirements (including 
ongoing precision and recovery (OPR) and method blank (MB) results, 
holding times, and positive and negative staining controls) were 
performed at the required frequency and were acceptable. Alternatively, 
the laboratory may provide for each field, MS, OPR, and MB sample a 
bench sheet and sample examination report form (Method 1622 and 1623 
bench sheets are shown in USEPA 2003h).
    Systems must report all routine source water Cryptosporidium 
monitoring results collected during the

[[Page 47728]]

period covered by the previously collected data that have been 
submitted. This applies to all samples that were collected from the 
sampling location used for monitoring, not spiked, and analyzed using 
the laboratory's routine process for Method 1622 or 1623 analyses, 
including analytical technique and QA/QC. Other requirements associated 
with use of previously collected data are specified in section 
IV.A.1.d. Where applicable, systems must provide documentation 
addressing the dates and reason(s) for re-sampling, as well as the use 
of presedimentation, off-stream storage, or bank filtration during 
monitoring. Review of the submitted information, along with the results 
of the quality assurance audits of the laboratory that produced the 
data, will be used to determine whether the data meet the requirements 
for grandfathering.

          Table IV-33.--Items That Must Be Reported for Consideration of Grandfathered Monitoring Data
----------------------------------------------------------------------------------------------------------------
            The following items must be reported \1\                      On the following schedule \1\
----------------------------------------------------------------------------------------------------------------
Data elements listed in Table IV-29 for each field and MS        No later than 2 months after promulgation if
 sample.                                                          the system does not intend to conduct new
                                                                  monitoring under the LT2ESWTR.
Letter from laboratory certifying that method-specified QC was
 performed at required frequency and was acceptable.
OR                                                               OR
Method 1622/1623 bench sheet and sample examination report form  No later than 8 months after promulgation if
 for each field, MS, OPR, and method blank sample.                the system intends to conduct new monitoring
                                                                  under the LT2ESWTR.
Letter from system certifying (1) that all source water data     ...............................................
 collected during the time period covered by the previously
 collected data have been submitted and (2) that the data
 represent the plant's current source water.
Where applicable, documentation addressing the dates and         ...............................................
 reason(s) for re-sampling, as well as the use of
 presedimentation, off-stream storage, or bank filtration
 during monitoring.
----------------------------------------------------------------------------------------------------------------
\1\ See section IV.A.1. for details.

3. Compliance With Additional Treatment Requirements
    Under the proposed LT2ESWTR, systems may choose from a ``toolbox'' 
of management and treatment options to meet their additional 
Cryptosporidium treatment requirements. In order to receive credit for 
toolbox components, systems must initially demonstrate that they comply 
with any required design and implementation criteria, including 
performance validation testing. Additionally, systems must provide 
monthly verification of compliance with any required operational 
criteria, as shown through ongoing monitoring. Required design, 
implementation, operational, and monitoring criteria for toolbox 
components are described in section IV.C. Proposed reporting 
requirements associated with these criteria are shown in Table IV-34 
for both large and small systems.

                                  Table IV-34.--Toolbox Reporting Requirements
----------------------------------------------------------------------------------------------------------------
                                                                           On the following
   Toolbox option  (potential                                                schedule \1\       On the following
 Cryptosporidium reduction log     You must submit the following items   (systems serving =10,000      (systems serving
                                                                                people)         < 10,000 people)
----------------------------------------------------------------------------------------------------------------
Watershed Control Program (WCP)  Notify State of intention to develop    No later than 48      No later than 78
 (0.5 log)                        WCP.                                    months after          months after
                                 Submit initial WCP plan to State......   promulgation          promulgation.
                                                                         No later than 60      No later than 90
                                                                          months after          months after
                                                                          promulgation.         promulgation.
                                 Annual program status report and State- By a date determined  By a date
                                  approved watershed survey report.       by the State, every   determined by
                                                                          12 months,            the State, every
                                                                          beginning 84 months   12 months,
                                                                          after promulgation    beginning 114
                                                                                                months after
                                                                                                promulgation.
                                 Request for re-approval and report on   No later than 6       No later than 6
                                  the previous approval period.           months prior to the   months prior to
                                                                          end of the current    the end of the
                                                                          approval period or    current approval
                                                                          by a date             period or by a
                                                                          previously            date previously
                                                                          determined by the     determined by
                                                                          State                 the State.
Pre-sedimentation (0.5 log)      Monthly verification of:                Monthly reporting     Monthly reporting
 (new basins)                    Continuous basin operation............   within 10 days        within 10 days
                                 Treatment of 100% of the flow.........   following the month   following the
                                 Continuous addition of a coagulant....   in which the          month in which
                                 At least 0.5 log removal of influent     monitoring was        the monitoring
                                  turbidity based on the monthly mean     conducted,            was conducted,
                                  of daily turbidity readings for 11 of   beginning 72 months   beginning 102
                                  the 12 previous months.                 after promulgation    months after
                                                                                                promulgation.
Two-Stage Lime Softening (0.5    Monthly verification of:                No later than 72      No later than 102
 log)                            Continuous operation of a second         months after          months after
                                  clarification step between the          promulgation          promulgation.
                                  primary clarifier and filter.
                                 Presence of coagulant (may be lime) in
                                  first and second stage clarifiers.
                                 Both clarifiers treat 100% of the
                                  plant flow.

[[Page 47729]]

 
Bank filtration (0.5 or 1.0      Initial demonstration of:               Initial               Initial
 log) (new)                      Unconsolidated, predominantly sandy      demonstration no      demonstration no
                                  aquifer.                                later than 72         later than 102
                                 Setback distance of at least 25 ft.      months after          months after
                                  (0.5 log) or 50 ft. (1.0 log).          promulgation          promulgation.
                                 If monthly average of daily max         Report within 30      Report within 30
                                  turbidity is greater than 1 NTU then    days following the    days following
                                  system must report result and submit    month in which the    the month in
                                  an assessment of the cause              monitoring was        which the
                                                                          conducted,            monitoring was
                                                                          beginning 72 months   conducted,
                                                                          after promulgation    beginning 102
                                                                                                months after
                                                                                                promulgation.
Combined filter performance      Monthly verification of:                Monthly reporting     Monthly
 (0.5 log)                       Combined filter effluent (CFE)           within 10 days        reporting:
                                  turbidity levels less than or equal     following the month   within 10 days
                                  to 0.15 NTU in at least 95 percent of   in which the          following the
                                  the 4 hour CFE measurements taken       monitoring was        month in which
                                  each month.                             conducted,            the monitoring
                                                                          beginning on 72       was conducted,
                                                                          months after          beginning on 102
                                                                          promulgation          months after
                                                                                                promulgation.
Membranes (MF, UF, NF, RO) (2.5  Initial demonstration of:               No later than 72      No later than 102
 log or greater based on         Removal efficiency through challenge     months after          months after
 verification/integrity           studies.                                promulgation          promulgation.
 testing)                        Methods of challenge studies meet rule
                                  criteria.
                                 Integrity test results and baseline...
                                 Monthly report summarizing:             Within 10 days        Within 10 days
                                 All direct integrity test results        following the month   following the
                                  above the control limit and the         in which monitoring   month in which
                                  corrective action that was taken.       was conducted,        monitoring was
                                 All indirect integrity monitoring        beginning 72 months   conducted,
                                  results triggering direct integrity     after promulgation    beginning 102
                                  testing and the corrective action                             months after
                                  that was taken.                                               promulgation.
Bag filters (1.0 log) and        Initial demonstration that the          No later than 72      No later than 102
 Cartridge filters (2.0 log)      following criteria are met:             months after          months after
                                 Process meets the basic definition of    promulgation          promulgation.
                                  bag or cartridge filtration;.
                                 Removal efficiency established through
                                  challenge testing that meets rule
                                  criteria.
                                 Challenge test shows at least 2 and 3
                                  log removal for bag and cartridge
                                  filters, respectively.
Chlorine dioxide (log credit     Summary of CT values for each day and   Within 10 days        Within 10 days
 based on CT)                     log inactivation based on tables in     following the month   following the
                                  section IV.C.14                         in which monitoring   month in which
                                                                          was conducted,        monitoring was
                                                                          beginning 72 months   conducted,
                                                                          after promulgation    beginning 102
                                                                                                months after
                                                                                                promulgation.
Ozone (log credit based on CT)   Summary of CT values for each day and   Within 10 days        Within 10 days
                                  log inactivation based on tables in     following the month   following the
                                  section IV.C.14                         in which monitoring   month in which
                                                                          was conducted,        monitoring was
                                                                          beginning 72 months   conducted,
                                                                          after promulgation    beginning 102
                                                                                                months after
                                                                                                promulgation.
UV (log credit based UV dose     Results from reactor validation         No later than 72      No later than 102
 and operating within validated   testing demonstrating operating         months after          months after
 conditions)                      conditions that achieve required UV     promulgation          promulgation.
                                  dose
                                 Monthly report summarizing the          Within 10 days        Within 10 days
                                  percentage of water entering the        following the month   following the
                                  distribution system that was not        in which monitoring   month in which
                                  treated by UV reactors operating        was conducted,        monitoring was
                                  within validated conditions for the     beginning 72 months   conducted,
                                  required UV dose in section IV.C.15     after promulgation    beginning 102
                                                                                                months after
                                                                                                promulgation.
Individual filter performance    Monthly verification of the following,  Monthly reporting     Monthly
 (1.0 log)                        based on continuous monitoring of       within 10 days        reporting:
                                  turbidity for each individual filter:   following the month   within 10 days
                                 Filtered water turbidity less than 0.1   in which the          following the
                                  NTU in at least 95 percent of the       monitoring was        month in which
                                  daily maximum values from individual    conducted,            the monitoring
                                  filters (excluding 15 minute period     beginning on 72       was conducted,
                                  following start up after backwashes).   months after          beginning 102
                                 No individual filter with a measured     promulgation          months after
                                  turbidity greater than 0.3 NTU in two                         promulgation.
                                  consecutive measurements taken 15
                                  minutes apart.
Demonstration of Performance     Results from testing following State    No later than 72      No later than 102
                                  approved protocol.                      months after          months after
                                                                          promulgation          promulgation.

[[Page 47730]]

 
                                 Monthly verification of operation       Within 10 days        Within 10 days
                                  within State-approved conditions for    following the month   following the
                                  demonstration of performance credit     in which monitoring   month in which
                                                                          was conducted,        monitoring was
                                                                          beginning 72 months   conducted,
                                                                          after promulgation    beginning 102
                                                                                                months after
                                                                                                promulgation.
----------------------------------------------------------------------------------------------------------------
\1\ States may allow an additional two years for systems making capital improvements.

    Reporting requirements associated with disinfection profiling and 
benchmarking are summarized in Table IV-35 for large systems and in 
Table IV-36 for small systems.

                Table IV-35.--Disinfection Benchmarking Reporting Requirements for Large Systems
----------------------------------------------------------------------------------------------------------------
                                                                   Submit the following      On the following
            System type                  Benchmark component               items                 schedule
----------------------------------------------------------------------------------------------------------------
Systems required to conduct          Characterization of          Giardia lamblia and     No later than 36
 Cryptosporidium monitoring.          Disinfection Practices.      virus inactivation      months after
                                                                   profiles must be on     promulgation.
                                                                   file for State review
                                                                   during sanitary
                                                                   survey.
                                     State Review of Proposed     Inactivation profiles   Prior to significant
                                      Changes to Disinfection      and benchmark           modification of
                                      Practices.                   determinations.         disinfection
                                                                                           practice.
Systems not required to conduct      Applicability..............  None..................  None.
 Cryptosporidium monitoring\1\.
                                     Characterization of          None..................  None.
                                      Disinfection Practices.
                                     State Review of Proposed     None..................  None.
                                      Changes to Disinfection
                                      Practices.
----------------------------------------------------------------------------------------------------------------
\1\Systems that provide at least 5.5 log of Cryptosporidium treatment consistent with a Bin 4 treatment
  implication are not required to conduct Cryptosporidium monitoring.


                Table IV-36.--Disinfection Benchmarking Reporting Requirements for Small Systems
----------------------------------------------------------------------------------------------------------------
                                                                   Submit the following      On the following
            System type                  Benchmark component               items                 schedule
----------------------------------------------------------------------------------------------------------------
Systems required to conduct          Characterization of          Giardia lamblia and     No later than 66
 Cryptosporidium monitoring.          Disinfection Practices.      virus inactivation      months after
                                                                   profiles must be on     promulgation.
                                                                   file for State review
                                                                   during sanitary
                                                                   survey.
                                     State Review of Proposed     Inactivation profiles   Prior to significant
                                      Changes to Disinfection      and benchmark           modification of
                                      Practices.                   determinations.         disinfection
                                                                                           practice.
Systems not required to conduct      Applicability Period.......  Notify State that       No later than 42
 Cryptosporidium monitoring and                                    profiling is required   months after
 that exceed DBP triggers\1,2,3\.                                  based on DBP levels.    promulgation.
                                     Characterization of          Giardia lamblia and     No later than 54
                                      Disinfection Practices.      virus inactivation      months after
                                                                   profiles must be on     promulgation.
                                                                   file for State review
                                                                   during sanitary
                                                                   survey.
                                     State Review of Proposed     Inactivation profiles   Prior to significant
                                      Changes to Disinfection      and benchmark           modification of
                                      Practices.                   determinations.         disinfection
                                                                                           practice.
Systems not required to conduct      Applicability Period.......  Notify State that       No later than 42
 Cryptosporidium monitoring and                                    profiling is not        months after
 that do not exceed DBP                                            required based on DBP   promulgation.
 triggers\2,3\.                                                    levels.
                                     Characterization of          None..................  None.
                                      Disinfection Practices.
                                     State Review of Proposed     None..................  None.
                                      Changes to Disinfection
                                      Practices.
----------------------------------------------------------------------------------------------------------------
\1\ Systems that provide at least 5.5 log of Cryptosporidium treatment consistent with a Bin 4 treatment
  implication are not required to conduct Cryptosporidium monitoring.
\2\ If the E. coli annual mean concentration is <= 10/100 mL for systems using lakes/reservoir sources or <= 50/
  100 mL for systems using flowing stream sources, the system is not required to conduct Cryptosporidium
  monitoring and will only be required to characterize disinfection practices if DBP triggers are exceeded.

[[Page 47731]]

 
\3\ If the system is a CWS or NTNCWSs and TTHM or HAA5 levels in the distribution system are at least 0.064 mg/L
  or 0.048 mg/L, respectively, calculated as an LRAA at any Stage 1 DBPR sampling site, then the system is
  triggered into disinfection profiling.

4. Request for Comment
    EPA requests comment on the reporting and recordkeeping 
requirements proposed for the LT2ESWTR.
    Specifically, the Agency requests comment on the proposed 
requirement that systems report monthly on the use of microbial toolbox 
components to demonstrate compliance with their Cryptosporidium 
treatment requirements. An alternative may be for systems to keep 
records on site for State review instead of reporting the data.

K. Analytical Methods

    EPA is proposing to require public water systems to conduct 
LT2ESWTR monitoring using approved methods for Cryptosporidium, E. 
coli, and turbidity analyses. This includes meeting quality control 
criteria stipulated by the approved methods and additional method-
specific requirements, as stated later in this section. Related 
requirements on the use of approved laboratories are discussed in 
section IV.L, and proposed requirements for reporting of data were 
stated previously in section IV.J. EPA has developed draft guidance for 
sampling and analyses under the LT2ESWTR (see USEPA 2003g and 2003h). 
This guidance is available in draft form in the docket for today's 
proposal (http://www.epa.gov/edocket/).
1. Cryptosporidium
    a. What is EPA proposing today? Method 1622: ``Cryptosporidium in 
Water by Filtration/IMS/FA'' (EPA-821-R-01-026, April 2001) (USEPA 
2001e) and Method 1623: ``Cryptosporidium and Giardia in Water by 
Filtration/IMS/FA'' (EPA 821-R-01-025, April 2001) (USEPA 2001f) are 
proposed for Cryptosporidium analysis under this rule. Methods 1622 and 
1623 require filtration, immunomagnetic separation (IMS) of the oocysts 
from the captured material, and examination based on IFA, DAPI staining 
results, and differential interference contrast (DIC) microscopy for 
determination of oocyst concentrations.
Method Requirements
    For each Cryptosporidium sample under this proposal, all systems 
must analyze at least a 10-L sample volume. Systems may collect and 
analyze greater than a 10-L sample volume. If a sample is very turbid, 
it may generate a large packed pellet volume upon centrifugation (a 
packed pellet refers to the concentrated sample after centrifugation 
has been performed in EPA Methods 1622 and 1623). Based on IMS 
purification limitations, samples resulting in large packed pellets 
will require that the sample concentrate be aliquoted into multiple 
``subsamples'' for independent processing through IMS, staining, and 
examination. Because of the expense of the IMS reagents and analyst 
time to examine multiple slides per sample, systems are not required to 
analyze more than 2 mL of packed pellet volume per sample.
    In cases where it is not feasible for a system to process a 10-L 
sample for Cryptosporidium analysis (e.g., filter clogs prior to 
filtration of 10 L) the system must analyze as much sample volume as 
can be filtered by 2 filters, up to a packed pellet volume of 2 mL. 
This condition applies only to filters that have been approved by EPA 
for nationwide use with Methods 1622 and 1623--the Pall Gelman 
EnvirochekTM and EnvirochekTM HV filters, the 
IDEXX Filta-MaxTM foam filter, and the Whatman 
CrypTestTM cartridge filter.
    Methods 1622 and 1623 include fluorescein isothiocyanate (FITC) as 
the primary antibody stain for Cryptosporidium detection, DAPI staining 
to detect nuclei, and DIC to detect internal structures. For purposes 
of the LT2ESWTR, systems must report total Cryptosporidium oocysts as 
detected by FITC as determined by the color (apple green or alternative 
stain color approved for the laboratory under the Lab QA Program 
described in section VI.L), size (4-6 [mu]m) and shape (round to oval). 
This total includes all of the oocysts identified as described here, 
less atypical organisms identified by FITC, DIC, or DAPI (e.g., 
possessing spikes, stalks, appendages, pores, one or two large nuclei 
filling the cell, red fluorescing chloroplasts, crystals, spores, 
etc.).
Matrix Spike Samples
    As required by Method 1622 and 1623, systems must have 1 matrix 
spike (MS) sample analyzed for each 20 source water samples. The volume 
of the MS sample must be within ten percent of the volume of the 
unspiked sample that is collected at the same time, and the samples 
must be collected by splitting the sample stream or collecting the 
samples sequentially. The MS sample and the associated unspiked sample 
must be analyzed by the same procedure. MS samples must be spiked and 
filtered in the laboratory. However, if the volume of the MS sample is 
greater than 10 L, the system is permitted to filter all but 10 L of 
the MS sample in the field, and ship the filtered sample and the 
remaining 10 L of source water to the laboratory. In this case, the 
laboratory must spike the remaining 10 L of water and filter it through 
the filter used to collect the balance of the sample in the field.
    EPA is proposing to require the use of flow cytometer-counted 
spiking suspensions for spiked QC samples during the LT2ESWTR. This 
provision is based on the improved precision expected for spiking 
suspensions counted with a flow cytometer, as compared to those counted 
using well slides or hemacytometers. During the Information Collection 
Rule Supplemental Surveys, the mean relative standard deviation (RSD) 
across 25 batches of flow cytometer-sorted Cryptosporidium spiking 
suspensions was 1.8%, with a median of 1.7% (Connell et al. 2000). In 
EPA Performance Evaluation (PE) studies, the mean RSD for flow 
cytometer sorted Cryptosporidium spiking suspensions was 3.4%. In 
comparison, the mean RSD for Cryptosporidium spiking suspensions 
enumerated manually by 20 laboratories using well slides or 
hemacytometers was 17% across 108 rounds of 10-replicate counts.
    QC requirements in Methods 1622 and 1623 must be met by 
laboratories analyzing Cryptosporidium samples under the LT2ESWTR. The 
QC acceptance criteria are the same as stipulated in the method. For 
the initial precision and recovery (IPR) test, the mean Cryptosporidium 
recovery must be 24% to 100% with maximum relative standard deviation 
(i.e., precision) of 55%. For each ongoing precision and recovery (OPR) 
sample, recovery must be in the range of 11% to 100%. For each method 
blank, oocysts must be undetected.
    Methods 1622 and 1623 are performance-based methods and, therefore, 
allow multiple options to perform the sample processing steps in the 
methods if a laboratory can meet applicable QC criteria and uses the 
same determinative technique. If a laboratory uses the same procedures 
for all samples, then all field samples and QC samples must be analyzed 
in that same manner. However, if a laboratory uses more than one set of 
procedures for Cryptosporidium analyses under LT2ESWTR then the 
laboratory must analyze separate QC samples for each

[[Page 47732]]

option to verify compliance with the QC criteria. For example, if the 
laboratory analyzes samples using both the EnvirochekTM and 
Filta-MaxTM filters, a separate set of IPR, OPR, method 
blank, and MS samples must be analyzed for each filtration option.
    b. How was this proposal developed? EPA is proposing EPA Methods 
1622 and 1623 for Cryptosporidium analyses under the LT2ESWTR because 
these are the best available methods that have undergone full 
validation testing. In addition, these methods have been used 
successfully in a national source water monitoring program as part of 
the Information Collection Rule Supplemental Surveys (ICRSS). The 
minimum sample volume and other quality control requirements are 
intended to ensure that data are of sufficient quality to assign 
systems to LT2ESWTR risk bins. Further, the proposed method 
requirements for analysis of Cryptosporidium are consistent with 
recommendations by the Stage 2 M-DBP Advisory Committee. In the 
Agreement in Principle, the Committee recommended that source water 
Cryptosporidium monitoring under the LT2ESWTR be conducted using EPA 
Methods 1622 and 1623 with no less than 10 L samples. EPA also has 
proposed these methods for approval for ambient water monitoring under 
Guidelines Establishing Test Procedures for the Analysis of Pollutants; 
Analytical Methods for Biological Pollutants in Ambient Water (66 FR 
45811, August 30, 2001) (USEPA 2001i).
    When considering the method performance that could be achieved for 
analysis of Cryptosporidium under the LT2ESWTR, EPA and the Advisory 
Committee evaluated the Cryptosporidium recoveries reported for Methods 
1622 and 1623 in the ICRSS. As described in section III.C, the ICRSS 
was a national monitoring program that involved 87 utilities sampling 
twice per month over 1 year for Cryptosporidium and other 
microorganisms and water quality parameters. During the ICRSS, the mean 
recovery and relative standard deviation associated with enumeration of 
MS samples for total oocysts by Methods 1622 and 1623 were 43% and 47%, 
respectively (Connell et al. 2000).
    EPA believes that with provisions like the Laboratory QA Program 
for Cryptosporidium laboratories (see section IV.L), comparable 
performance to that observed in the ICRSS can be achieved in LT2ESWTR 
monitoring with the use of Methods 1622 and 1623, and that this level 
of performance will be sufficient to realize the public health goals 
intended by EPA and the Advisory Committee for the LT2ESWTR. Other 
methods would need to achieve comparable performance to be considered 
for use under the LT2ESWTR. For example, EPA does not expect the 
Information Collection Rule Method, which resulted in 12% mean recovery 
for MS samples during the Information Collection Rule Laboratory 
Spiking Program (Scheller, 2002), to meet LT2ESWTR data quality 
objectives.
    For systems collecting samples larger than 10 L, EPA is proposing 
the approach of allowing systems to filter all but 10 L of the 
corresponding MS sample in the field, and ship the filtered sample and 
the remaining 10 L of source water to the laboratory for spiking and 
analysis. The Agency has determined that the added costs associated 
with shipping entire high-volume (e.g. 50-L) samples to a laboratory 
for spiking and analysis are not merited by improved data quality 
relative to the use of Cryptosporidium MS data under the LT2ESWTR. EPA 
estimates that the average cost for shipping a 50-L bulk water sample 
is $350 more than the cost of shipping a 10-L sample and a filter. A 
study comparing these two approaches (i.e., spiking and filtering 50 L 
vs. field filtering 40 L and spiking 10 L) indicated that spiking the 
10-L sample produced somewhat higher recoveries (USEPA 2003i). However, 
the differences were not significant enough to offset the greatly 
increased shipping costs, given the limited use of MS data in LT2ESWTR 
monitoring.
    c. Request for comment. EPA requests comment on the proposed method 
requirements for Cryptosporidium analysis, including the following 
specific issues:
Minimum Sample Volume
    It is the intent of EPA that LT2ESWTR sampling provide 
representative annual mean source water concentrations. If systems were 
unable to analyze an entire sample volume during certain periods of the 
year due to elevated turbidity or other water quality factors, this 
could result in systems analyzing different volumes in different 
samples. Today's proposal requires systems to analyze at least 10 L of 
sample or the maximum amount of sample that can be filtered through two 
filters, up to a packed pellet volume of 2 mL. EPA requests comment on 
whether these requirements are appropriate for systems with source 
waters that are difficult to filter or that generate a large packed 
pellet volume. Alternatively, systems could be required to filter and 
analyze at least 10 L of sample with no exceptions.
Approval of Updated Versions of EPA Methods 1622 and 1623
    EPA has developed draft revised versions of EPA Methods 1622 and 
1623 in order to consolidate several method-related changes EPA 
believes may be necessary to address LT2ESWTR monitoring requirements 
(see USEPA 2003j and USEPA 2003k). EPA is requesting comment on whether 
these revised versions should be approved for monitoring under the 
LT2ESWTR, rather than the April 2001 versions proposed in today's rule. 
If the revised versions were approved, previously collected data 
generated using the earlier versions of the methods would still be 
acceptable for grandfathering, provided the other criteria described in 
section IV.A.1.d were met. Drafts of the updated methods are provided 
in the docket for today's rule, and differences between these versions 
and the April 2001 versions of the methods are clearly indicated for 
evaluation and comment. Changes to the methods include the following:

    (1) Increased flexibility in matrix spike (MS) and initial 
precision and recovery (IPR) requirements--the requirement that the 
laboratory must analyze an MS sample on the first sampling event for 
a new PWS would be changed to a recommendation; the revised method 
would allow the IPR test to be performed across four different days, 
rather than restrict analyses to 1 day;
    (2) Clarification of some method procedures, including the 
spiking suspension vortexing procedure and the buffer volumes used 
during immunomagnetic separation (IMS); requiring (rather than 
recommending) that laboratories purchase HCl and NaOH standards at 
the normality specified in the method; and clarification that the 
use of methanol during slide staining in section 14.2 of the method 
is as per manufacturer's instructions;
    (3) Additional recommendations for minimizing carry-over of 
debris onto microscope slides after IMS and information on 
microscope cleaning;
    (4) Clarification in the method of the actions to take in the 
event of QC failures, such as that any positive sample in a batch 
associated with an unacceptable method blank is unacceptable and 
that any sample in a batch associated with an unacceptable ongoing 
precision and recovery (OPR) sample is unacceptable;
    (5) Changes to the sample storage and shipping temperature to 
``less than 10[deg]C and not frozen'', and additional guidance on 
sample storage and shipping procedures that addresses time of 
collection, and includes suggestions for monitoring sample 
temperature during shipment and upon receipt at the laboratory.
    (6) Additional analyst verification procedures--adding 
examination using differential interference contrast (DIC) 
microscopy to the analyst verification requirements.

[[Page 47733]]

    (7) Addition of an approved method modification using the Pall 
Gelman Envirochek HV filter. This approval was based on an 
interlaboratory validation study demonstrating that three 
laboratories, each analyzing reagent water and a different source 
water, met all method acceptance criteria for Cryptosporidium. EPA 
issued a letter (dated March 21, 2002) under the Alternative Test 
Procedures program approving the procedure as an acceptable version 
of Method 1623 for Cryptosporidium (but not for Giardia). EPA also 
noted in the letter that the procedure was considered to be an 
acceptable modification of EPA Method 1622.
    (8) Incorporation of detailed procedures for concentrating 
samples using an IDEXX Filta-MaxTM foam filter. A method 
modification using this filter already is approved by EPA in the 
April 2001 versions of the methods.
    (9) Addition of BTF EasySeedTM irradiated oocysts and 
cysts as acceptable materials for spiking routine QC samples. EPA 
approved the use of EasySeedTM based on side-by-side 
comparison tests of method recoveries using EasySeedTM 
and live, untreated organisms. EPA issued a letter (dated August 1, 
2002) approving EasySeedTM for use in routine QC samples 
for EPA Methods 1622 and 1623 and for demonstrating comparability of 
method modifications in a single laboratory.
    (10) Removal of the Whatman Nuclepore CrypTestTM 
cartridge filter. Although a method modification using this filter 
was approved by EPA in the April 2001 versions of the methods, the 
filter is no longer available from the manufacturer, and so is no 
longer an option for sample filtration.

    The changes in the June 2003 draft revisions of EPA Methods 1622 
and 1623 reflect method-related clarifications, modifications, and 
additions that EPA believes should be addressed for LT2ESWTR 
Cryptosporidium monitoring. Alternatively, these issues could be 
addressed through regulatory requirements in the final LT2ESWTR (for 
required changes and additions) and through guidance (for recommended 
changes and clarifications). However, EPA believes that addressing 
these issues through a single source in updated versions of EPA Methods 
1622 and 1623 (which could be approved in the final LT2ESWTR) may be 
more straightforward and easier for systems and laboratories to follow 
than addressing them in multiple sources (i.e., existing methods, the 
final rule, and laboratory guidance).
2. E. coli
    a. What is EPA proposing today? For enumerating source water E. 
coli density under the LT2ESWTR, EPA is proposing to approve the same 
methods that were proposed by EPA under Guidelines Establishing Test 
Procedures for the Analysis of Pollutants; Analytical Methods for 
Biological Pollutants in Ambient Water (66 FR 45811, August 30, 2001) 
(USEPA 2001i). These methods are summarized in Table IV-37. Methods are 
listed within the general categories of most probable number tests and 
membrane filtration tests. Method identification numbers are provided 
for applicable standards published by EPA and voluntary consensus 
standards bodies (VCSB) including Standard Methods, American Society of 
Testing Materials (ASTM), and the Association of Analytical Chemists 
(AOAC).

                                               Table IV-37.-- Proposed Methods for E. Coli Enumeration \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                             VCSB methods
                                                                               ---------------------------------------
          Technique                        Method\1\                   EPA        Standard                                     Commercial example
                                                                                 methods\2\    ASTM\3\      AOAC\4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Most Probable Number (MPN)...  LTB, EC-MUG......................  ............     9221B.1/
                                                                                      9221F
                               ONPG-MUG.........................  ............        9223B  ...........       991.15  Colilert[reg]\5\.
                               ONPG-MUG.........................  ............        9223B  ...........  ...........  Colilert-18[reg]5 7.
Membrane Filter (MF).........  mFC[rtarr3]NA-MUG................  ............       9222D/
                                                                                      9222G
                               mENDO or LES-ENDO[rtarr3]NA-MUG..  ............       9222B/
                                                                                      9222G
                               mTEC agar........................        1103.1        9213D     D5392-93
                               Modified mTEC agar...............        1603
                               MI medium........................        1604
                               m-ColiBlue24 broth...............  ............  ...........  ...........  ...........  m-ColiBlue24\6\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Tests must be conducted in a format that provides organism enumeration.
\2\ Standard Methods for the Examination of Water and Wastewater. American Public Health Association. 20th, 19th, and 18th Editions. Amer. Publ. Hlth.
  Assoc., Washington, DC.
\3\ Annual Book of ASTM Standards--Water and Environmental Technology. Section 11.02. ASTM. 100 Barr Harbor Drive, West Conshohocken, PA 19428.
\4\ Official Methods of Analysis of AOAC International, 16th Edition, Volume I, Chapter 17. AOAC International. 481 North Frederick Avenue, Suite 500,
  Gaithersburg, Maryland 20877-2417.
\5\ Manufactured by IDEXX Laboratories, Inc., One IDEXX Drive, Westbrook, Maine 04092.
\6\ Manufactured by Hach Company, 100 Dayton Ave., Ames, IA 50010.
\7\ Acceptable version of method approved as a drinking water alternative test procedure.

    EPA is proposing to allow a holding time of 24 hours for E. coli 
samples. The holding time refers to the time between sample collection 
and initiation of analysis. Currently, 40 CFR 141.74(a) limits the 
holding time for source water coliform samples to 8 hours and requires 
that samples be kept below 10[deg]C during transit. EPA believes that 
new studies, described later in this section, demonstrate that E. coli 
analysis results for samples held for 24 hours will be comparable to 
samples held for 8 hours, provided the samples are held below 10[deg]C 
and are not allowed to freeze. This proposed increase in holding time 
is significant for the LT2ESWTR because typically it is not feasible 
for systems to meet an 8-hour holding time when samples cannot be 
analyzed on-site. Many small systems that will conduct E. coli 
monitoring under the LT2ESWTR lack a certified on-site laboratory for 
E. coli analyses and will be required to ship samples to a certified 
laboratory. EPA believes that it is feasible for these systems to 
comply with a 24 hour holding time for E. coli samples through using 
overnight delivery services.
    b. How was this proposal developed? As noted, EPA recently proposed 
methods for ambient water E. coli analysis under Guidelines 
Establishing Test Procedures for the Analysis of Pollutants; Analytical 
Methods for

[[Page 47734]]

Biological Pollutants in Ambient Water (66 FR 45811, August 30, 2001) 
(USEPA 2001i). These proposed methods were selected based on data 
generated by EPA laboratories, submissions to the alternate test 
procedures (ATP) program and voluntary consensus standards bodies, 
published peer reviewed journal articles, and publicly available study 
reports.
    The source water analysis for E. coli that will be conducted under 
the LT2ESWTR is similar to the type of ambient water analyses for which 
these methods were previously proposed (66 FR 45811, August 30, 2001) 
(USEPA 2001i). EPA continues to support the findings of this earlier 
proposal and believes that these methods have the necessary sensitivity 
and specificity to meet the data quality objectives of the LT2ESWTR.
New Information on E. coli Sample Holding Time
    It is generally not feasible for systems that must ship E. coli 
samples to an off-site laboratory to comply with an 8-hour holding time 
requirement. During the ICRSS, 100% of the systems that shipped samples 
off-site for E. coli analysis exceeded the 8 hour holding time; 12% of 
these samples had holding times in excess of 30 hours. Most large 
systems that will be required to monitor for E. coli under the LT2ESWTR 
could conduct these analyses on-site, but many small systems will need 
to ship samples off-site to a certified contract laboratory.
    EPA participated in three phases of studies to assess the effect of 
increased sample holding time on E. coli analysis results. These are 
summarized as follows, and are described in detail in Pope et al. 
(2003).
    [sbull] Phase 1-EPA, the Wisconsin State Laboratory of Hygiene 
(WSLH), and DynCorp conducted a study to evaluate E. coli sample 
concentrations from four sites at 8, 24, 30, and 48 hours after sample 
collection for samples stored at 4[deg]C, 10[deg]C, 20[deg]C, and 
35[deg]C. Temperature was varied to assess the effect of different 
shipping conditions. Samples were analyzed in triplicate by membrane 
filtration (mFC followed by transfer to NA-MUG) and Colilert (Quanti-
Tray 2000) (Pope et al. 2003).
    [sbull] Phase 2-EPA conducted a study to evaluate E. coli sample 
concentrations from seven sites at 8, 24, 30, and 48 hours after sample 
collection for samples stored in coolers containing wet ice or Utek ice 
packs (to assess real-world storage conditions). Samples were analyzed 
in triplicate by membrane filtration (mFC followed by transfer to NA-
MUG) and Colilert (Quanti-Tray 2000) (Pope et al. 2003).
    [sbull] Phase 3-EPA, through cooperation with AWWA, obtained E. 
coli holding time data from ten drinking water utilities that evaluated 
samples from 12 source waters. Each utility used an E. coli method of 
its choice (Colilert, mTEC, mEndo to NA-MUG, or mFC to NA-MUG). Samples 
were stored in coolers with wet ice, Utek ice packs, or Blue ice (Pope 
et al. 2003).
    Phase 1 results indicated that E. coli concentrations were not 
significantly different after 24 hours at most sites when samples were 
stored at lower temperatures. Results from Phase 2, which evaluated 
actual sample storage practices, verified the Phase 1 observations at 
most sites. Similar results were observed during Phase 3, which 
evaluated a wider variety of surface waters from different regions 
throughout the U.S. During Phase 3, E. coli concentrations were not 
significantly different after 24 hours at most sites when samples were 
maintained below 10[deg]C and did not freeze during storage. At longer 
holding times (e.g., 48 hours), larger differences were observed.
    Based on these studies, EPA has concluded that E. coli samples can 
be held for up to 24 hours prior to analysis without compromising the 
data quality objectives of LT2ESWTR E. coli monitoring. Further, EPA 
believes that it is feasible for systems that must ship E. coli samples 
to an off-site laboratory for analysis to meet a 24 hour holding time. 
EPA is developing guidance for systems on packing and shipping E. coli 
samples so that samples are maintained below 10[deg]C and not allowed 
to freeze (USEPA 2003g). This guidance is available in draft in the 
docket for today's proposal (http://www.epa.gov/edocket/).
    c. Request for comment. EPA requests comment on whether the E. coli 
methods proposed for approval under the LT2ESWTR are appropriate, and 
whether there are additional methods not proposed that should be 
considered. Comments concerning method approval should be accompanied 
by supporting data where possible.
    EPA also requests comment on the proposal to extend the holding 
time for E. coli source water sample analyses to 24 hours, including 
any data or other information that would support, modify, or repudiate 
such an extension. Should EPA limit the extended holding time to only 
those E. coli analytical methods that were evaluated in the holding 
time studies noted in this section? The results in Pope et al. (2003) 
indicate that most E. coli samples analyzed using ONPG-MUG (see methods 
in Table IV-37) incurred no significant degradation after a 30 to 48 
hour holding time. As a result, should EPA increase the source water E. 
coli holding time to 30 or 48 hours for samples evaluated by ONPG-MUG, 
and retain a 24-hour holding time for samples analyzed by other 
methods? EPA also requests comment on the cost and availability of 
overnight delivery services for E. coli samples, especially in rural 
areas.
3. Turbidity
     a. What is EPA proposing today? For turbidity analyses that will 
be conducted under the LT2ESWTR, EPA is proposing to require systems to 
use the analytical methods that have been previously approved by EPA 
for analysis of turbidity in drinking water, as listed in 40 CFR Part 
141.74. These are Method 2130B as published in Standard Methods for the 
Examination of Water and Wastewater (APHA 1992), EPA Method 180.1 
(USEPA 1993), and Great Lakes Instruments Method 2 (Great Lakes 
Instruments, 1992), and Hach FilterTrak Method 10133.
    EPA method 180.1 and Standard Method 2130B are both nephelometric 
methods and are based upon a comparison of the intensity of light 
scattered by the sample under defined conditions with the intensity of 
light scattered by a standard reference suspension. Great Lakes 
Instruments Method 2 is a modulated four beam infrared method using a 
ratiometric algorithm to calculate the turbidity value from the four 
readings that are produced. Hach Filter Trak (Method 10133) is a laser-
based nephelometric method used to determine the turbidity of finished 
drinking waters.
Turbidimeters
    Systems are required to use turbidimeters described in EPA-approved 
methods for measuring turbidity. For regulatory reporting purposes, 
either an on-line or a bench top turbidimeter can be used. If a system 
chooses to use on-line units for monitoring, the system must validate 
the continuous measurements for accuracy on a regular basis using a 
protocol approved by the State.
    b. How was this proposal developed? EPA believes the currently 
approved methods for analysis of turbidity in drinking water are 
appropriate for turbidity analyses that will be conducted under the 
LT2ESWTR.
    c. Request for comment. EPA requests comment on whether the 
turbidity methods proposed today for the LT2ESWTR should be approved, 
and whether there are additional methods not proposed that should be 
approved.

[[Page 47735]]

L. Laboratory Approval

    Given the potentially significant implications in terms of both 
cost and public health protection of microbial monitoring under the 
LT2ESWTR, laboratory analyses for Cryptosporidium, E. coli, and 
turbidity must be accurate and reliable within the limits of approved 
methods. Therefore, EPA proposes to require public water systems to use 
laboratories that have been approved to conduct analyses for these 
parameters by EPA or the State. The following criteria are proposed for 
laboratory approval under the LT2ESWTR:
    [sbull] For Cryptosporidium analyses under the LT2ESWTR, EPA 
proposes to approve laboratories that have passed a quality assurance 
evaluation under EPA's Laboratory Quality Assurance Evaluation Program 
(Lab QA Program) for Analysis of Cryptosporidium in Water (described in 
67 FR 9731, March 4, 2002) (USEPA 2002c). If States adopt an equivalent 
approval process under State laboratory certification programs, then 
systems can use laboratories approved by the State.
    [sbull] For E. coli analyses, EPA proposes to approve laboratories 
that have been certified by EPA, the National Environmental Laboratory 
Accreditation Conference, or the State for total coliform or fecal 
coliform analysis in source water under 40 CFR 141.74. The laboratory 
must use the same analytical technique for E. coli that the laboratory 
uses for total coliform or fecal coliform analysis under 40 CFR 141.74.
    [sbull] Turbidity analyses must be conducted by a person approved 
by the State for analysis of turbidity in drinking water under 40 CFR 
141.74.
    These criteria are further described in the following paragraphs.
1. Cryptosporidium Laboratory Approval
    Because States do not currently approve laboratories for 
Cryptosporidium analyses and LT2ESWTR monitoring will begin 6 months 
after rule promulgation, EPA will initially assume responsibility for 
Cryptosporidium laboratory approval. EPA expects, however, that States 
will include Cryptosporidium analysis in their State laboratory 
certification programs in the future. EPA has established the Lab QA 
Program for Cryptosporidium analysis to identify laboratories that can 
meet LT2ESWTR data quality objectives. This is a voluntary program open 
to laboratories involved in analyzing Cryptosporidium in water. Under 
this program, EPA assesses the ability of laboratories to reliably 
measure Cryptosporidium occurrence with EPA Methods 1622 and 1623, 
using both performance testing samples and an on-site evaluation.
    EPA initiated the Lab QA Program for Cryptosporidium analysis prior 
to promulgation of the LT2ESWTR to ensure that adequate sample analysis 
capacity will be available at qualified laboratories to support the 
required monitoring. The Agency is monitoring sample analysis capacity 
at approved laboratories through the Lab QA Program, and does not plan 
to implement LT2ESWTR monitoring until the Agency determines that there 
is adequate laboratory capacity. In addition, utilities that choose to 
conduct Cryptosporidium monitoring prior to LT2ESWTR promulgation with 
the intent of grandfathering the data may elect to use laboratories 
that have passed the EPA quality assurance evaluation.
    Laboratories seeking to participate in the EPA Lab QA Program for 
Cryptosporidium analysis must submit an interest application to EPA, 
successfully analyze a set of initial performance testing samples, and 
undergo an on-site evaluation. The on-site evaluation includes two 
separate but concurrent assessments: (1) Assessment of the laboratory's 
sample processing and analysis procedures, including microscopic 
examination, and (2) evaluation of the laboratory's personnel 
qualifications, quality assurance/quality control program, equipment, 
and recordkeeping procedures.
    Laboratories that pass the quality assurance evaluation will be 
eligible for approval for Cryptosporidium analysis under the LT2ESWTR. 
The Lab QA Program is described in detail in a Federal Register Notice 
(67 FR 9731, March 4, 2002) (USEPA 2002c) and additional information 
can be found online at: www.epa.gov/safewater/lt2/cla_int.html.
    Laboratories in the Lab QA Program will receive a set of three 
ongoing proficiency testing (OPT) samples approximately every four 
months. EPA will evaluate the precision and recovery data for OPT 
samples to determine if the laboratory continues to meet the 
performance criteria of the Laboratory QA Program.
2. E. coli Laboratory Approval
    Pubic water systems are required to have samples analyzed for E. 
coli by laboratories certified under the State drinking water 
certification program to perform total coliform and fecal coliform 
analyses under 40 CFR 141.74. EPA is proposing that the general 
analytical techniques the laboratory is certified to use under the 
drinking water certification program (e.g., membrane filtration, 
multiple-well, multiple-tube) will be the methods the laboratory can 
use to conduct E. coli source water analyses under the LT2ESWTR.
3. Turbidity Analyst Approval
    Measurements of turbidity must be conducted by a party approved by 
the State. This is consistent with current requirements for turbidity 
measurements in drinking water (40 CFR 141.74).
4. Request for Comment
    EPA requests comment on the laboratory approval requirements 
proposed today, including the following specific issues:
Analyst Experience Criteria
    The Lab QA Program, which EPA will use to approve laboratories for 
Cryptosporidium analyses under the LT2ESWTR, includes criteria for 
analyst experience. Principal analyst/supervisors (minimum of one per 
laboratory) should have a minimum of one year of continuous bench 
experience with Cryptosporidium and immunofluorescent assay (IFA) 
microscopy, a minimum of six months experience using EPA Method 1622 
and/or 1623, and a minimum of 100 samples analyzed using EPA Method 
1622 and/or 1623 (minimum 50 samples if the person was an analyst 
approved to conduct analysis for the Information Collection Rule 
Protozoan Method) for the specific analytical procedure they will be 
using.
    Under the Lab QA Program, other analysts (no minimum number of 
analysts per laboratory) should have a minimum of six months of 
continuous bench experience with Cryptosporidium and IFA microscopy, a 
minimum of three months experience using EPA Method 1622 and/or 1623, 
and a minimum of 50 samples analyzed using EPA Method 1622 and/or 1623 
(minimum 25 samples if the person was an analyst approved to conduct 
analysis for the Information Collection Rule Protozoan Method) for the 
specific analytical procedures they will be using.
    The Lab QA Program criteria for principal analyst/supervisor 
experience are more rigorous than those in Methods 1622 and 1623, which 
are as follows: the analyst must have at least 2 years of college 
lecture and laboratory course work in microbiology or a closely related 
field. The analyst also must have at least 6 months of continuous bench 
experience with environmental protozoa detection techniques and IFA

[[Page 47736]]

microscopy, and must have successfully analyzed at least 50 water and/
or wastewater samples for Cryptosporidium. Six months of additional 
experience in the above areas may be substituted for two years of 
college.
    In seeking approval for an Information Collection Request, EPA 
requested comment on the Lab QA Program (67 FR 9731, March 4, 2002) 
(USEPA 2002c). A number of commenters stated that the analyst 
qualification criteria are restrictive and could make it difficult for 
laboratories to maintain adequate analyst staffing (and, hence, sample 
analysis capacity) in the event of staff turnover or competing 
priorities. Some commenters suggested that laboratories and analysts 
should be evaluated based on proficiency testing, and that analyst 
experience standards should be reduced or eliminated. (Comments are 
available in Office of Water docket, number W-01-17).
    Another aspect of the analyst experience criteria is that systems 
may generate Cryptosporidium data for grandfathering under the LT2ESWTR 
using laboratories that meet the analyst experience requirement of 
Methods 1622 or 1623 but not the more rigorous principal analyst/
supervisor experience requirement of the Lab QA Program.
    EPA requests comment on whether the criteria for analyst experience 
in the Lab QA Program are necessary, whether systems are experiencing 
difficulty in finding laboratories that have passed the Lab QA Program 
to conduct Cryptosporidium analysis, and whether any of the Lab QA 
Program criteria should be revised to improve the LT2ESWTR lab approval 
process.
State Programs To Approve Laboratories for Cryptosporidium Analysis
    Under today's proposal, systems must have Cryptosporidium samples 
analyzed by a laboratory approved under EPA's Lab QA Program, or an 
equivalent State laboratory approval program. Because States do not 
currently approve laboratories for Cryptosporidium analyses, EPA will 
initially assume responsibility for Cryptosporidium laboratory 
approval. EPA expects, however, that States will adopt equivalent 
approval programs for Cryptosporidium analysis under State laboratory 
certification programs. EPA requests comment on how to establish that a 
State approval program for Cryptosporidium analysis is equivalent to 
the Lab QA Program.
    Specifically, should EPA evaluate State Approval programs to 
determine if they are equivalent to the Lab QA Program? EPA also 
requests comment on the elements that would constitute an equivalent 
State approval program for Cryptosporidium analyses, including the 
following: (1) Successful analysis of initial and ongoing blind 
proficiency testing samples prepared using flow cytometry, including a 
matrix and meeting EPA's pass/fail criteria (described in USEPA 2002c); 
(2) an on-site evaluation of the laboratory's sample processing and 
analysis procedures, including microscopic examination skills, by 
auditors who meet the qualifications of a principal analyst as set 
forth in the Lab QA Program (described in USEPA 2002c); (3) an on-site 
evaluation of the laboratory's personnel qualifications, quality 
assurance/quality control program, equipment, and recordkeeping 
procedures; (4) a data audit of the laboratories' QC data and 
monitoring data; and (5) use of the audit checklist used in the Lab QA 
Program or equivalent.

M. Requirements for Sanitary Surveys Conducted by EPA

1. Overview
    In today's proposal, EPA is requesting comment on establishing 
requirements for public water systems with significant deficiencies as 
identified in a sanitary survey conducted by EPA under SDWA section 
1445. These requirements would apply to surface water systems for which 
EPA is responsible for directly implementing national primary drinking 
water regulations (i.e., systems not regulated by States with primacy). 
As described in this section, these requirements would ensure that 
systems in non-primacy States, currently Wyoming, and systems not 
regulated by States, such as Tribal systems, are subject to standards 
for sanitary surveys similar to those that apply to systems regulated 
by States with primacy.
2. Background
    As established by the IESWTR in 40 CFR 142.16(b)(3), primacy States 
must conduct sanitary surveys for all surface water systems no less 
frequently than every three years for community water systems and no 
less frequently than every five years for noncommunity water systems. 
The sanitary survey is an onsite review and must address the following 
eight components: (1) Source, (2) treatment, (3) distribution system, 
(4) finished water storage, (5) pumps, pump facilities, and controls, 
(6) monitoring, reporting, and data verification, (7) system management 
and operation, and (8) operator compliance with State requirements.
    Under the IESWTR, primacy States are required to have the 
appropriate rules or other authority to assure that systems respond in 
writing to significant deficiencies outlined in sanitary survey reports 
no later than 45 days after receipt of the report, indicating how and 
on what schedule the system will address significant deficiencies noted 
in the survey (40 CFR 142.16(b)(1)(ii)). Further, primacy States must 
have the authority to assure that systems take necessary steps to 
address significant deficiencies identified in sanitary survey reports 
if such deficiencies are within the control of the system and its 
governing body (40 CFR 142.16(b)(1)(iii)). The IESWTR did not define a 
significant deficiency, but required that primacy States describe in 
their primacy applications how they will decide whether a deficiency 
identified during a sanitary survey is significant for the purposes of 
the requirements stated in this paragraph (40 CFR 142.16(b)(3)(v)).
    EPA conducts sanitary surveys under SDWA section 1445 for public 
water systems not regulated by primacy States (e.g., Tribal systems, 
Wyoming). However, EPA does not have the authority required of primacy 
States under 40 CFR 142 to ensure that systems address significant 
deficiencies identified during sanitary surveys. Consequently, the 
sanitary survey requirements established by the IESWTR create an 
unequal standard. Systems regulated by primacy States are subject to 
the States' authority to require correction of significant deficiencies 
noted in sanitary survey reports, while systems for which EPA has 
direct implementation authority do not have to meet an equivalent 
requirement.
3. Request for Comment
    In order to ensure that systems for which EPA has direct 
implementation authority address significant deficiencies identified 
during sanitary surveys, EPA requests comment on establishing either or 
both of the following requirements under 40 CFR 141 as part of the 
NPDWR established in the final LT2ESWTR:

    (1) For sanitary surveys conducted by EPA under SDWA section 
1445, systems would be required to respond in writing to significant 
deficiencies outlined in sanitary survey reports no later than 45 
days after receipt of the report, indicating how and on what 
schedule the system will address significant deficiencies noted in 
the survey.
    (2) Systems would be required to correct significant 
deficiencies identified in sanitary survey reports if such 
deficiencies are within the control of the system and its governing 
body.

[[Page 47737]]

    For the purposes of these requirements, a sanitary survey, as 
conducted by EPA, is an onsite review of the water source (identifying 
sources of contamination by using results of source water assessments 
where available), facilities, equipment, operation, maintenance, and 
monitoring compliance of a public water system to evaluate the adequacy 
of the system, its sources and operations, and the distribution of safe 
drinking water. A significant deficiency includes a defect in design, 
operation, or maintenance, or a failure or malfunction of the sources, 
treatment, storage, or distribution system that EPA determines to be 
causing, or has the potential for causing the introduction of 
contamination into the water delivered to consumers.

V. State Implementation

    This section describes the regulations and other procedures and 
policies States will be required to adopt to implement the LT2ESWTR, if 
finalized as proposed today. States must continue to meet all other 
conditions of primacy in 40 CFR Part 142.
    The Safe Drinking Water Act (Act) establishes requirements that a 
State or eligible Indian tribe must meet to assume and maintain primary 
enforcement responsibility (primacy) for its public water systems. 
These requirements include: (1) Adopting drinking water regulations 
that are no less stringent than Federal drinking water regulations, (2) 
adopting and implementing adequate procedures for enforcement, (3) 
keeping records and making reports available on activities that EPA 
requires by regulation, (4) issuing variances and exemptions (if 
allowed by the State), under conditions no less stringent than allowed 
under the Act, and (5) adopting and being capable of implementing an 
adequate plan for the provisions of safe drinking water under emergency 
situations.
    40 CFR part 142 sets out the specific program implementation 
requirements for States to obtain primacy for the public water supply 
supervision program as authorized under section 1413 of the Act. In 
addition to adopting basic primacy requirements specified in 40 CFR 
Part 142, States may be required to adopt special primacy provisions 
pertaining to specific regulations where implementation of the rule 
involves activities beyond general primacy provisions. States must 
include these regulation specific provisions in an application for 
approval of their program revision. Primacy requirements for today's 
proposal are discussed below.
    To implement the proposed LT2ESWTR, States will be required to 
adopt revisions to:
Sec.  141.2--Definitions
Sec.  141.71--Criteria for avoiding filtration
Sec.  141.153--Content of the reports
Sec.  141.170--Enhanced filtration and disinfection
Subpart Q--Public Notification
New Subpart W--Additional treatment technique requirements for 
Cryptosporidium
Sec.  142.14--Records kept by States
Sec.  142.15--Reports by States
Sec.  142.16--Special primacy requirements

A. Special State Primacy Requirements

    To ensure that a State program includes all the elements necessary 
for an effective and enforceable program under today's rule, a State 
primacy application must include a description of how the State will 
perform the following:
    (1) Approve watershed control programs for the 0.5 log watershed 
control program credit in the microbial toolbox (see section IV.C.2);
    (2) Assess significant changes in the watershed and source water as 
part of the sanitary survey process and determine appropriate follow-up 
action (see section IV.A);
    (3) Determine that a system with an uncovered finished water 
storage facility has a risk mitigation plan that is adequate for 
purposes of waiving the requirement to cover the storage facility or 
treat the effluent (see section IV.E);
    (4) Approve protocols for removal credits under the Demonstration 
of Performance toolbox option (see section IV.C.17) and for site 
specific chlorine dioxide and ozone CT tables (see section IV.C.14); 
and
    (5) Approve laboratories to analyze for Cryptosporidium.
    Note that a State program can be more, but not less, stringent than 
Federal regulations. As such, some of the elements listed here may not 
be applicable to a specific State program. For example, if a State 
chooses to require all finished water storage facilities to be covered 
or provide treatment and not to allow a risk mitigation plan to 
substitute for this requirement, then the description for item (3) 
would be inapplicable.

B. State Recordkeeping Requirements

    The current regulations in Sec.  142.14 require States with primacy 
to keep various records, including the following: Analytical results to 
determine compliance with MCLs, MRDLs, and treatment technique 
requirements; system inventories; State approvals; enforcement actions; 
and the issuance of variances and exemptions. The proposed LT2ESWTR 
will require States to keep additional records of the following, 
including all supporting information and an explanation of the 
technical basis for each decision:
    [sbull] Results of source water E. coli and Cryptosporidium 
monitoring;
    [sbull] Cryptosporidium bin classification for each filtered 
system, including any changes to initial bin classification based on 
review of the watershed during sanitary surveys or the second round of 
monitoring;
    [sbull] Determination of whether each unfiltered system has a mean 
source water Cryptosporidium level above 0.01 oocysts/L;
    [sbull] The treatment processes or control measures that each 
system employs to meet Cryptosporidium treatment requirements under the 
LT2ESWTR; this includes documentation to demonstrate compliance with 
required design and implementation criteria for receiving credit for 
microbial toolbox options, as specified in section IV.C;
    [sbull] A list of systems required to cover or treat the effluent 
of an uncovered finished water storage facilities; and
    [sbull] A list of systems for which the State has waived the 
requirement to cover or treat the effluent of an uncovered finished 
water storage facility, along with supporting documentation of the risk 
mitigation plan.

C. State Reporting Requirements

    EPA currently requires in Sec.  142.15 that States report to EPA 
information such as violations, variance and exemption status, and 
enforcement actions. The LT2ESWTR, as proposed, will add additional 
reporting requirements in the following area:
    [sbull] The Cryptosporidium bin classification for each filtered 
system, including any changes to initial bin classification based on 
review of the watershed during sanitary surveys or the second round of 
monitoring;
    [sbull] The determination of whether each unfiltered system has a 
mean source water Cryptosporidium level above 0.01 oocysts/L, including 
any changes to this determination based on the second round of 
monitoring.

D. Interim Primacy

    On April 28, 1998, EPA amended its State primacy regulations at 40 
CFR 142.12 to incorporate the new process identified in the 1996 SDWA 
Amendments for granting primary enforcement authority to States while 
their applications to modify their primacy programs are under review 
(63 FR 23362, April 28, 1998) (USEPA 1998f). The new process grants 
interim

[[Page 47738]]

primary enforcement authority for a new or revised regulation during 
the period in which EPA is making a determination with regard to 
primacy for that new or revised regulation. This interim enforcement 
authority begins on the date of the primacy application submission or 
the effective date of the new or revised State regulation, whichever is 
later, and ends when EPA makes a final determination. However, this 
interim primacy authority is only available to a State that has primacy 
(including interim primacy) for every existing NPDWR in effect when the 
new regulation is promulgated.
    As a result, States that have primacy for every existing NPDWR 
already in effect may obtain interim primacy for this rule, beginning 
on the date that the State submits the application for this rule to 
USEPA, or the effective date of its revised regulations, whichever is 
later. In addition, a State that wishes to obtain interim primacy for 
future NPDWRs must obtain primacy for this rule. As described in 
Section IV.A, EPA expects to oversee the initial source water 
monitoring that will be conducted under the LT2ESWTR by systems serving 
at least 10,000 people, beginning 6 months following rule promulgation.

VI. Economic Analysis

    This section summarizes the economic analysis (EA) for the LT2ESWTR 
proposal. The EA is an assessment of the benefits, both health and non-
health related, and costs to the regulated community of the proposed 
regulation, along with those of regulatory alternatives that the Agency 
considered. EPA developed this EA to meet the requirement of SDWA 
section 1412(b)(3)(C) for a Health Risk Reduction and Cost Analysis 
(HRRCA), as well as the requirements of Executive Order 12866, 
Regulatory Planning and Review, under which EPA must estimate the costs 
and benefits of the LT2ESWTR. The full EA is presented in Economic 
Analysis for the Long Term 2 Enhanced Surface Water Treatment Rule 
(USEPA 2003a), which is available in the docket for today's proposal 
(www.epa.gov.edocket/).
    Today's proposed LT2ESWTR is the second in a staged set of rules 
that address public health risks from microbial contamination of 
surface and GWUDI drinking water supplies and, more specifically, 
prevent Cryptosporidium from reaching consumers. As described in 
section I, the Agency promulgated the IESWTR and LT1ESWTR to provide a 
baseline of protection against Cryptosporidium in large and small 
drinking water systems, respectively. Today's proposed rule would 
achieve further reductions in Cryptosporidium exposure for systems with 
the highest vulnerability. This economic analysis considers only the 
incremental reduction in exposure from the two previously promulgated 
rules (IESWTR and LT1ESWTR) to the alternatives evaluated for the 
LT2ESWTR.
    Both benefits and costs are determined as annualized present 
values. The process allows comparison of cost and benefit streams that 
are variable over a given time period. The time frame used for both 
benefit and cost comparisons is 25 years; approximately five years 
account for rule implementation and 20 years for the average useful 
life of the equipment used to comply with treatment technique 
requirements. The Agency uses social discount rates of both three 
percent and seven percent to calculate present values from the stream 
of benefits and costs and also to annualize the present value estimates 
(see EPA's Guidelines for Preparing Economic Analyses (USEPA 2000c) for 
a discussion of social discount rates). The LT2ESWTR EA (USEPA 2003a) 
also shows the undiscounted stream of both benefits and costs over the 
25 year time frame.

A. What Regulatory Alternatives Did the Agency Consider?

    Regulatory alternatives considered by Agency for the LT2ESWTR were 
developed through the deliberations of the Stage 2 M-DBP Federal 
Advisory Committee (described in section II). The Committee considered 
several general approaches for reducing the risk from Cryptosporidium 
in drinking water. As discussed in section IV.A.2, these approaches 
included both additional treatment requirements for all systems and 
risk-targeted treatment requirements for systems with the highest 
vulnerability to Cryptosporidium following implementation of the IESWTR 
and LT1ESWTR. In addition, the Committee considered related factors 
such as surrogates for Cryptosporidium monitoring and alternative 
monitoring strategies to minimize costs to small drinking water 
systems.
    After considering these general approaches, the Committee focused 
on four specific regulatory alternatives for filtered systems (see 
Table VI-1). With the exception of Alternative 1, which requires all 
systems to achieve an additional 2 log (99%) reduction in 
Cryptosporidium levels, these alternatives incorporate a microbial 
framework approach. In this approach, systems are classified in 
different risk bins based on the results of source water monitoring. 
Additional treatment requirements are directly linked to the risk bin 
classification. Accordingly, these rule alternatives are differentiated 
by two criteria: (1) The Cryptosporidium concentrations that define the 
bin boundaries and (2) the degree of treatment required for each bin.
    In assessing regulatory alternatives, EPA and the Advisory 
Committee were concerned with the following questions: (1) Do the 
treatment requirements adequately control Cryptosporidium 
concentrations in finished water? (2) How many systems will be required 
to add treatment? (3) What is the likelihood that systems with high 
source water Cryptosporidium concentrations will not be required to 
provide additional treatment (i.e., be misclassified in a low risk 
bin)? and (4) What is the likelihood that systems with low source water 
Cryptosporidium concentrations will be required to provide unnecessary 
additional treatment (i.e., misclassified in a high risk bin)?
    The Committee reached consensus regarding additional treatment 
requirements for unfiltered systems and uncovered finished water 
storage facilities without formally identifying regulatory 
alternatives. Table VI-1 summarizes the four alternatives that were 
considered for filtered systems.

[[Page 47739]]



  Table VI-1.--Summary of Regulatory Alternatives for Filtered Systems
------------------------------------------------------------------------
     Average source water Cryptosporidium         Additional treatment
         monitoring result (oocysts/L)              requirements \1\
------------------------------------------------------------------------
                             Alternative A1
              2.0 log inactivation required for all systems
                             Alternative A2
------------------------------------------------------------------------
< 0.03........................................  No action.
= 0.03 and < 0.1...................  0.5 log.
= 0.1 and < 1.0....................  1.5 log.
= 1.0..............................  2.5 log.
-----------------------------------------------
                  Alternative A3--Preferred Alternative
------------------------------------------------------------------------
< 0.075.......................................  No action.
= 0.075 and < 1.0..................  1 log.
= 1.0 and < 3.0....................  2 log.
= 3.0..............................  2.5 log.
-----------------------------------------------
                             Alternative A4
------------------------------------------------------------------------
< 0.1.........................................  No action.
= 0.1 and < 1.0....................  0.5-log.
=1.0...............................  1.0 log.
------------------------------------------------------------------------
\1\ Note: ``Additional treatment requirements'' are in addition to
  levels already required under existing rules (e.g., the IESWTR and
  LT1ESWTR).

B. What Analyses Support Selecting the Proposed Rule Option?

    EPA has quantified benefits and costs of each of the regulatory 
alternatives in Table VI-1, as well as for the proposed requirements 
for unfiltered systems. Quantified benefits stem from estimated 
reductions in the incidence of cryptosporidiosis resulting from the 
regulation. To make these estimates, the Agency developed a two-
dimensional Monte Carlo model that accounts for uncertainty and 
variability in key parameters like Cryptosporidium occurrence, 
infectivity, and treatment efficiency. Analyses involved estimating the 
baseline (pre-LT2ESWTR) risk from Cryptosporidium in drinking water, 
and then projecting the reductions in exposure and risk resulting from 
the additional treatment requirements of the LT2ESWTR. Costs result 
largely from the installation of additional treatment, with lesser 
costs due to monitoring and other implementation activities. Results of 
these analyses are summarized in the following subsections, and details 
are shown in the LT2ESWTR EA (USEPA 2003a).
    Cryptosporidium occurrence significantly influences the estimated 
benefits and costs of regulatory alternatives. As discussed in section 
III.C, EPA analyzed data collected under the Information Collection 
Rule, the Information Collection Rule Supplemental Surveys of medium 
systems (ICRSSM), and the Information Collection Rule Supplemental 
Surveys of large systems (ICRSSL) to estimate the national occurrence 
distribution of Cryptosporidium in surface water. EPA evaluated these 
distributions independently when assessing benefits and costs for 
different regulatory alternatives. In most cases, results from the 
ICRSSM data set are within the range of results of the Information 
Collection Rule and ICRSSL data sets.
    EPA selected a Preferred Regulatory Alternative for the LT2ESWTR, 
consistent with the recommendations of the Advisory Committee. As 
described next, this selection was based on the estimated impacts and 
feasibility of the alternatives shown in Table VI-1.
    Alternative A1 (across-the-board 2-log inactivation) was not 
selected because it was the highest cost option and imposed costs but 
provided few benefits to systems with high quality source water (i.e., 
relatively low Cryptosporidium risk). In addition, there were concerns 
about the feasibility of requiring almost every surface water treatment 
plant to install additional treatment processes (e.g., UV or ozone) for 
Cryptosporidium.
    Alternatives A2-A4 were evaluated based on several factors, 
including predictions of costs and benefits, performance of analytical 
methods for classifying systems in the risk bins, and other specific 
impacts (e.g., impacts on small systems or sensitive subpopulations). 
Alternative A3 was recommended by the Advisory Committee because it 
provides significant health benefits in terms of avoided illnesses and 
deaths for an acceptable cost. In addition, the Agency believes this 
alternative is feasible with available analytical methods and treatment 
technologies.
    Incremental costs and benefits of regulatory alternatives for the 
LT2ESWTR are shown in section VI.F, and the LT2ESWTR EA contains more 
detailed information about the benefits and costs of each regulatory 
option (USEPA 2003a).

C. What Are the Benefits of the Proposed LT2ESWTR?

    As discussed previously, the LT2ESWTR is expected to substantially 
reduce drinking water related exposure to Cryptosporidium, thereby 
reducing both illness and death associated with cryptosporidiosis. As 
described in section II, cryptosporidiosis is an infection caused by 
Cryptosporidium and is an acute, typically self-limiting, illness with 
symptoms that include diarrhea, abdominal cramping, nausea, vomiting, 
and fever (Juranek, 1995). Cryptosporidiosis patients in sensitive 
subpopulations, such as infants, the elderly, and AIDS patients, are at 
risk for severe illness, including risk of death. While EPA has 
quantified and monetized the health benefits for reductions in endemic 
cryptosporidiosis that would result from the LT2ESWTR, the Agency was 
unable to quantify or monetize other health and non-health related 
benefits associated with this rule. These unquantified benefits are 
characterized next, followed by a summary of the quantified benefits.

[[Page 47740]]

1. Non-Quantifiable Health and Non-health Related Benefits
    Although there are substantial monetized benefits that result from 
this rule due to reduced rates of endemic cryptosporidiosis, other 
potentially significant benefits of this rule remain unquantified and 
non-monetized. The unquantified benefits that result from this rule are 
summarized in Table VI-2 and are described in greater detail in the 
LT2ESWTR EA (USEPA 2003a).

             Table VI-2.--Summary of Nonquantified Benefits
------------------------------------------------------------------------
                                 Potential effect
         Benefit type              on benefits            Comments
------------------------------------------------------------------------
Reducing outbreak risks and     Increase.........  Some outbreaks are
 response costs.                                    caused by human or
                                                    equipment failures
                                                    that may occur even
                                                    with the proposed
                                                    new requirements;
                                                    however, by adding
                                                    barriers of
                                                    protection for some
                                                    systems, the rule
                                                    will reduce the
                                                    possibility of such
                                                    failures leading to
                                                    outbreaks.
Reducing averting behavior      Increase / No      Averting behavior is
 (e.g., boiling tap water or     Change.            associated with both
 purchasing bottled water).                         out-of-pocket costs
                                                    (e.g., purchase of
                                                    bottled water) and
                                                    opportunity costs
                                                    (e.g., time
                                                    requiring to boil
                                                    water) to the
                                                    consumer. Reductions
                                                    in averting behavior
                                                    are expected to have
                                                    a positive impact on
                                                    benefits from the
                                                    rule.
Improving aesthetic water       Increase.........  Some technologies
 quality.                                           installed for this
                                                    rule (e.g., ozone)
                                                    are likely to reduce
                                                    taste quality and
                                                    odor problems.
Reducing risk from co-          Increase.........  Although focused on
 occurring and emerging                             removal of
 pathogens.                                         Cryptosporidium from
                                                    drinking water,
                                                    systems that change
                                                    treatment processes
                                                    will also increase
                                                    removal of pathogens
                                                    that the rule does
                                                    not specifically
                                                    regulate. Additional
                                                    benefits will
                                                    accrue.
Increased source water          Increase.........  The greater
 monitoring.                                        understanding of
                                                    source water quality
                                                    that results from
                                                    monitoring may
                                                    enhance the ability
                                                    of plants to
                                                    optimize treatment
                                                    operations in ways
                                                    other than those
                                                    addressed in this
                                                    rule.
Reduced contamination due to    Increase.........  Although insufficient
 covering on treating finished                      data were available
 water storage facilities.                          to quantify
                                                    benefits, the
                                                    reduction of
                                                    contaminants
                                                    introduced through
                                                    uncovered finished
                                                    water storage
                                                    facilities would
                                                    produce positive
                                                    public health
                                                    benefits.
------------------------------------------------------------------------
Source: Chapter 5 of the LT2ESWTR Economic Analysis (USEPA 2003a).

2. Quantifiable Health Benefits
    EPA quantified benefits for the LT2ESWTR based on reductions in the 
risk of endemic cryptosporidiosis. Several categories of monetized 
benefits were considered in this analysis.
    First, EPA estimated the number of cases expected to result in 
premature mortality (primarily for members of sensitive subpopulations 
such as AIDS patients). In order to estimate the benefits from deaths 
avoided as a result of the rule, EPA multiplied the estimates for 
number of illnesses avoided by a projected mortality rate. This 
mortality rate was developed using mortality data from the Milwaukee 
cryptosporidiosis outbreak of 1993 (described in section II), with 
adjustments to account for the subsequent decrease in the mortality 
rate among people with AIDS and for the difference between the 1993 
Milwaukee AIDS rate and the current national rate. EPA estimated a 
mortality rate of 16.6 deaths per 100,000 illnesses for those served by 
unfiltered systems and a mortality rate of 10.6 deaths per 100,000 
illnesses for those served by filtered systems. These different rates 
are associated with the incidence of AIDS in populations served by 
unfiltered and filtered systems. A complete discussion on how EPA 
derived these rates can be found in subchapter 5.2 of the LT2ESWTR EA 
(USEPA 2003a).
    Reductions in mortalities were monetized using EPA's standard 
methodology for monetizing mortality risk reduction. This methodology 
is based on a distribution of value of statistical life (VSL) estimates 
from 26 labor market and stated preference studies, with a mean VSL of 
$6.3M in 2000, and a 5th to 95th percentile range of $1.0 to $14.5. A 
more detailed discussion of these studies and the VSL estimate can be 
found in EPA's Guidelines for Preparing Economic Analyses (USEPA 
2000c). A real income growth factor was applied to these estimates of 
approximately 2.3% per year for the 20 year time span following 
implementation. Income elasticity for VSL was estimated as a triangular 
distribution that ranged from 0.08 to 1.00, with a mode of 0.40. VSL 
values for the 20 year span are shown in the LT2 EA in Exhibit C.13 
(USEPA 2003a).
    The substantial majority of cases are not expected to be fatal and 
the Agency separately estimated the value of non-fatal illnesses 
avoided that would result from the LT2ESWTR. For these, EPA first 
divided projected cases into three categories, mild, moderate, and 
severe, and then calculated a monetized value per case avoided for each 
severity level. These were then combined into a weighted average value 
per case based on the relative frequency of each severity level. 
According to a study conducted by Corso et al. (2003), the majority of 
illness falls into the mild category (88 percent). Approximately 11 
percent of illness falls into the moderate category, which is defined 
as those who seek medical treatment but are not hospitalized. The final 
one percent have severe symptoms that result in hospitalization. EPA 
estimated different medical expenses and time losses for each category.
    Benefits for non-fatal cases were calculated using a cost-of-
illness (COI) approach. Traditional COI valuations focus on medical 
costs and lost work time, and leave out significant categories of 
benefits, specifically the reduced utility from being sick (i.e., lost 
personal or non-work time, including activities such as child care, 
homemaking, community service, time spent with family, and recreation), 
although some COI studies also include an estimate for unpaid labor 
(household production) valued at an estimated wage

[[Page 47741]]

rate designed to reflect the market value of such labor (e.g., median 
wage for household domestic labor). This reduced utility is variously 
referred to as lost leisure or a component of pain and suffering. 
Ideally, a comprehensive willingness to pay (WTP) estimate would be 
used that includes all categories of loss in a single number. However, 
a review of the literature indicated that the available studies were 
not suitable for valuing cryptosporidiosis; hence, estimates from this 
literature are inappropriate for use in this analysis. Instead, EPA 
presents two COI estimates: a traditional approach that only includes 
valuation for medical costs and lost work time (including some portion 
of unpaid household production); and an enhanced approach that also 
factors in valuations for lost unpaid work time for employed people, 
reduced utility (or sense of well-being) associated with decreased 
enjoyment of time spent in non-work activities, and lost productivity 
at work on days when workers are ill but go to work anyway.
    Table VI-3 shows the various categories of loss and how they were 
valued for each estimate for a ``typical'' case (weighted average of 
severity level--see LT2ESWTR EA--Chapter 5 for more details (USEPA 
2003a).

     Table VI-3.--Traditional and Enhanced COI for Cryptosporidiosis
------------------------------------------------------------------------
                                            Traditional
              Loss category                     COI        Enhanced COI
------------------------------------------------------------------------
Direct Medical Costs....................          $93.82          $93.82
Lost Paid Work Days.....................          109.88          109.88
Lost Unpaid Work Days \1\...............           20.22           40.44
Lost Caregiver Days \2\.................           20.70           54.31
Lost Leisure Time \3\...................             \5\          333.96
Lost Productivity at Work...............             \5\          112.49
    Total \4\...........................          244.62         744.89
------------------------------------------------------------------------
\1\ Assigned to 38.2% of the population not engaged in market work;
  assumes 40 hr, unpaid work week, valued at $5.46/hr in traditional COI
  and $10.92/hr in enhanced COI. Does not include lost unpaid work for
  employed people and may not include all unpaid work for people outside
  the paid labor force.
\2\ Values lost work or leisure time for people caring for the ill.
  Traditional approach does not include lost leisure time.
\3\ Includes child care and homemaking (to the extent not covered in
  lost unpaid work days above), time with family, and recreation for
  people within and outside the paid labor force.
\4\ Detail may not calculate to totals due to independent rounding;
  Source: Appendix L in LT2ESWTR EA (USEPA 2003a).
\5\ Not included.

    The various loss categories were calculated as follows: Medical 
costs are a weighted average across the three illness severity levels 
of actual costs for doctor and emergency room visits, medication, and 
hospital stays. Lost paid work represents missed work time of paid 
employees, valued at the median pre-tax wage, plus benefits of $18.47 
hour. The average number of lost work hours per case is 5.95 (this 
assumes that 62 percent of the population is in the paid labor force 
and the loss is averaged over seven days). Medical costs and lost work 
days reflect market transactions. Medical costs are always included in 
COI estimates and lost work days are usually included in COI estimates.
    In the traditional COI estimate, an equivalent amount of lost 
unpaid work time was assigned to the 38% of the population that are not 
in the paid labor force. This includes homemakers, students, children, 
retires, and unemployed persons. EPA did not attempt to calculate what 
percent of cases falls in each of these five groups, or how many hours 
per week each group works, but rather assumed an across-the-board 40 
hour unpaid work week. This time is valued at $5.46 per hour, which is 
one half the median post-tax wage, (since work performed by these 
groups is not taxed). This is approximately the median wage for paid 
household domestic labor.
    In the enhanced COI estimate, all time other than paid work and 
sleep (8 hours per day) is valued at the median after tax wage, or 
$10.92 per hour. This includes lost unpaid work (e.g., household 
production) and leisure time for people within and outside the paid 
labor force. Implicit in this approach, is that people would pay the 
same amount not to be sick during their leisure time as they require to 
give up their leisure time to work (i.e., the after tax wage). In 
reality, people might be willing to pay either more than this amount 
(if they were very sick and suffering a lot) or less than this amount 
(if they were not very sick and still got some enjoyment out of 
activities such as resting, reading and watching TV), not to be sick. 
Multiplying 16 hours by $10.92 gives a value of about $175.00 for a day 
of ``lost'' unpaid work and leisure (i.e., lost utility of being sick).
    An estimate of lost unpaid work days for the enhanced approach was 
made by assigning the value of $10.92 per hour to the same number of 
unpaid work hours valued in the traditional COI approach (i.e., 40 
unpaid work hours per week for people outside the paid labor force). 
Lost unpaid work for employed people and any unpaid labor beyond 40 
hours per week for those not in the labor market is shown as lost 
leisure time in Table VI-3 for the enhanced approach and is not 
included in the traditional approach. In addition, for days when an 
individual is well enough to work but still experiencing symptoms, such 
as diarrhea, the enhanced estimate also includes a 30% loss of work and 
leisure productivity, based on a study of giardiasis illness 
(Harrington et al. 1985) which is similar to cryptosporidiosis. 
Appendix P in the EA describes similar productivity losses for other 
illnesses such as influenza (35%-73% productivity losses). In the 
traditional COI analysis, productivity losses are not included for 
either work or non-work time.
    The Agency believes that losses in productivity and lost leisure 
time are unquestionably present and that these categories have positive 
value; consequently, the traditional COI estimate understates the true 
value of these loss categories. EPA notes that these estimates should 
not be regarded as upper and lower bounds. In particular, the enhanced 
COI estimate may not fully incorporate the value of pain and suffering, 
as people may be willing to pay more than $201 to avoid a day of 
illness. The traditional COI estimate includes a valuation for a lost 
40 hour work week for all persons not in the labor force, including 
children and retirees. This may be an overstatement of lost 
productivity for these groups, which would depend on the impact of such 
things as missed

[[Page 47742]]

school work or volunteer activities that may be affected by illness.
    As with the avoided mortality valuation, the real wages used in the 
COI estimates were increased by a real income growth factor that varies 
by year, but is the equivalent of about 2.3% over the 20 year period. 
This approach of adjusting for real income growth was recommended by 
the SAB (USEPA 2000e) because the median real wage is expected to grow 
each year (by approximately 2.3%)--the median real wage is projected to 
be $38,902 in 2008 and $59,749 in 2027. Correspondingly, the real 
income growth factor of the COI estimates increases by the equivalent 
of 2.3% per year (except for medical costs, which are not directly tied 
to wages). This approach gives a total COI valuation in 2008 of $268.92 
for the traditional COI estimate and $931.06 for the enhanced COI 
estimate; the valuation in 2027 is $362.75 for the traditional COI 
estimate and $1,429.99 for the enhanced COI estimate. There is no 
difference in the methodology for calculating the COI over this 20 year 
period of implementation; the change in valuation is due to the 
underlying change in projected real wages.
    Table VI-4 summarizes the annual cases of cryptosporidiosis illness 
and associated deaths avoided due to the LT2ESWTR proposal. The 
proposed rule, on average, is expected to reduce 256,000 to 1,019,000 
illnesses and 37 to 141 deaths annually after full implementation 
(range based on the ICRSSL, ICRSSM, and Information Collection Rule 
data sets).

                            Table VI-4.--Summary of Annual Avoided Illness and Deaths
----------------------------------------------------------------------------------------------------------------
                                          Annual illinesses avoided                Annual deaths avoided
                                   -----------------------------------------------------------------------------
                                                   90 percent confidence                  90 percent confidence
             Data set                                      bound                                  bound
                                        Mean    --------------------------     Mean    -------------------------
                                                  Lower (5th     Upper                  Lower  (5th     Upper
                                                    %ile)     (95th %ile)                  %ile)     (95th %ile)
----------------------------------------------------------------------------------------------------------------
                                     Annual Total After Full Implementation
----------------------------------------------------------------------------------------------------------------
ICR...............................    1,018,915      169,358    2,331,467          141           25          308
ICRSSL............................      256,173       45,292      560,648           37            7           78
ICRSSM............................      498,363       84,724    1,177,415           70           13          157
-----------------------------------
                                          Annual Average Over 25 years
----------------------------------------------------------------------------------------------------------------
ICR...............................      720,668      119,694    1,647,796          100           18          218
ICRSSL............................      181,387       32,179      396,845           26            5           55
ICRSSM............................      352,611       59,942      833,290           50            9         111
----------------------------------------------------------------------------------------------------------------
Source: The LT2ESWTR Economic Analysis (USEPA 2003a).

    Tables VI-5a and VI-5b show the monetized present value of the 
benefit for reductions in endemic cryptosporidiosis estimated to result 
from the LT2ESWTR for the enhanced and traditional COI values, 
respectively. Estimates are given for the Information Collection Rule, 
ICRSSL, and ICRSSM occurrence data sets.
    With the enhanced COI and a three percent discount rate, the annual 
present value of the mean benefit estimate ranges from $374 million to 
$1.4 billion, with a 90 percent confidence bound of $52 million to $198 
million at the lower 5th percentile and $959 million to $3.7 billion at 
the upper 95th percentile; at a seven percent discount rate, this 
estimate ranges from $318 million to $1.2 billion, with a 90 percent 
confidence bound of $44 million to $168 million at the lower 5th 
percentile and $816 million to $3.1 billion at the upper 95th 
percentile. With the traditional COI, the corresponding benefit 
estimate at a three percent discount rate ranges from $253 million to 
$967 million, with a 90 percent confidence bound of $27 million to $105 
million at the lower 5th percentile and $713 million to $2.7 billion at 
the upper 95th percentile; for a seven percent discount rate, this 
estimate ranges from $216 million to $826 million, with a 90 percent 
confidence bound of $23 million to $89 million at the lower 5th 
percentile and $610 million to $2.3 billion at the upper 95th 
percentile. None of these values include the unquantified and non-
monetized benefits discussed previously.

                           Table VI-5A.--Summary of Quantified Benefits--Enhanced COI
                                               [$millions, 2000$]
----------------------------------------------------------------------------------------------------------------
                                                                        Value of benefits--Enhanced COI \1\
                                                                 -----------------------------------------------
                                                                                    90 percent confidence bound
                            Data set                                             -------------------------------
                                                                       Mean         Lower (5th     Upper  (95th
                                                                                       %ile)           %ile)
----------------------------------------------------------------------------------------------------------------
                                       Annualized Value (at 3%, 25 Years)
----------------------------------------------------------------------------------------------------------------
ICR.............................................................          $1,445            $198           3,666
ICRSSL..........................................................             374              52             959
ICRSSM..........................................................             715              96           1,849
-----------------------------------------------------------------
                                       Annualized Value (at 7%, 25 Years)
----------------------------------------------------------------------------------------------------------------
ICR.............................................................           1,230             168           3,120

[[Page 47743]]

 
ICRSSL..........................................................             318              44             816
ICRSSM..........................................................             609              81          1,577
----------------------------------------------------------------------------------------------------------------
\1\ The traditional COI only includes valuation for medical costs and lost work time (including some portion of
  unpaid household production). The enhanced COI also factors in valuations for lost personal time (non-
  worktime) such as child care and homemaking (to the extent not covered by the traditional COI), time with
  family, and recreation, and lost productivity at work on days when workers are ill but go to work anyway.
  Source: The LT2ESWR Economic Analysis (USEPA 2003a).


      Table VI-5b.--Summary of Quantified Benefits--Traditional COI
                           [($Millions, 2000$]
------------------------------------------------------------------------
                                          Value of Benefits--Traditional
                                                     COI \1\
                                        --------------------------------
                                                         90 percent
                Data Set                              confidence bound
                                                   ---------------------
                                            Mean      Lower      Upper
                                                       (5th       95th
                                                      %ile)      %ile)
------------------------------------------------------------------------
                   Annualized Value (at 3%, 25 Years)
------------------------------------------------------------------------
ICR....................................       $967       $105     $2,713
ICRSSL.................................        253         27        713
ICRSSM.................................        481         50      1,372
----------------------------------------
                   Annualized Value (at 7%, 25 Years)
------------------------------------------------------------------------
ICR....................................        826         89      2,315
ICRSSL.................................        216         23        610
ICRSSM.................................        411         43     1,172
------------------------------------------------------------------------
\1\ The traditional COI only includes valuation for medical costs and
  lost work time (including some portion of unpaid household
  production). The enhanced COI also factors in valuations for lost
  personal time (non-worktime) such as child care and homemaking (to the
  extent not covered by the traditional COI), time with family, and
  recreation, and lost productivity at work on days when workers are ill
  but go to work anyway. Source: The LT2ESWTR Economic Analysis (USEPA
  2003a).

    a. Filtered systems. Benefits to the approximately 161 million 
people served by filtered surface water and GWUDI systems range from 
88,000 to 472,000 reduction in mean annual cases of endemic illness 
based on ICRSSL, ICRSSM, and ICR data sets. In addition, premature 
mortality is expected to be reduced by an average of 9 to 50 deaths 
annually.
    b. Unfiltered systems. The 12 million people served by unfiltered 
surface water or GWUDI systems will see a significant reduction in 
cryptosporidiosis as a result of the LT2ESWTR. In this population, the 
rule is expected to reduce approximately 168,000 to 547,000 cases of 
illness and 28 to 91 premature deaths annually.
    For unfiltered systems, only the Information Collection Rule data 
set is used to directly calculate illness reduction because it is the 
only data set that includes sufficient information on unfiltered 
systems. Illness reduction in unfiltered systems was estimated for the 
ICRSSL and ICRSSM data sets by multiplying the Information Collection 
Rule unfiltered system result by the ratio, for the quantity estimated, 
between filtered system results from the supplemental survey data set 
(SSM or SSL) and filtered system results from the Information 
Collection Rule.
3. Timing of Benefits Accrual (Latency)
    In previous rulemakings, some commenters have argued that the 
Agency should consider an assumed time lag or latency period in its 
benefits calculations. The Agency has not conducted a latency analysis 
for this rule because cryptosporidiosis is an acute illness; therefore, 
very little time elapses between exposure, illness, and mortality. 
However, EPA does account for benefits and costs that occur in future 
years by converting these to present value estimates.

D. What Are the Costs of the Proposed LT2ESWTR?

    In order to estimate the costs of today's proposed rule, the Agency 
considered impacts on public water systems and on States (including 
territories and EPA implementation in non-primacy States). EPA assumed 
that systems would be in compliance with the IESWTR, which has a 
compliance date of January 2002 for large systems and the LT1ESWTR, 
which has a compliance date of January 2005 for small systems. 
Therefore, this cost estimate only considers the additional 
requirements that are a direct result of the LT2ESWTR. More detailed 
information on cost estimates are described next and a complete 
discussion can be found in chapter 6 of the LT2ESWTR EA (USEPA 2003a). 
An detailed discussion of the proposed rule provisions is located in 
section IV of this preamble.

[[Page 47744]]

1. Total Annualized Present Value Costs
    Tables VI-6a and VI-6b summarize the annualized present value cost 
estimates for the proposed LT2ESWTR at three percent and seven percent 
discount rates, respectively. The mean annualized present value costs 
of the proposed LT2ESWTR are estimated to range from approximately $73 
to $111 million using a three percent discount rate and $81 to $121 
million using a seven percent discount rate. This range in mean cost 
estimates is associated with the ICRSSL and Information Collection Rule 
Cryptosporidium occurrence data sets. Using different occurrence data 
sets results in different bin classifications and, thus, impacts the 
cost of the rule. Results for the ICRSSM fall within the range of 
results for the Information Collection Rule and ICRSSL. In addition to 
mean estimates of costs, the Agency calculated 90 percent confidence 
bounds by considering the uncertainty in Cryptosporidium occurrence 
estimates and around the mean unit technology costs (USEPA 2003a).
    Public water systems will incur approximately 99 percent of the 
rule's total annualized present value costs. States incur the remaining 
rule costs. Table VI-7 shows the undiscounted initial capital and one-
time costs broken out by rule component. A comparison of annualized 
present value costs among the rule alternatives considered by the 
Agency is located in subsection VI.F. and in the LT2ESWTR EA (USEPA 
2003a). Using a present value allows costs and benefits that occur 
during different time periods to be compared. For any future cost, the 
higher the discount rate, the lower the present value. Specifically, a 
future cost evaluated at a seven percent discount rate will always 
result in a lower total present value cost than the same future cost 
evaluated at a three percent discount rate.
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2. Water System Costs
    The proposed LT2ESWTR applies to all community, non-transient non-
community, and transient non-community water systems that use surface 
water or GWUDI as a source (including both filtered and unfiltered 
systems). EPA has estimated the cost impacts for these three types of 
public drinking water systems. As shown in Table VI-6a and VI-6b, the 
mean annualized present value costs for all drinking water systems 
range from approximately $73 to $111 million using a three percent 
discount rate ($81 to $121 million using a seven percent discount 
rates).
    The majority of costs of the rule result from treatment changes 
incurred by filtered and unfiltered systems. Table VI-8 shows the 
number of filtered and unfiltered systems that will incur costs by rule 
provision. Subsection VI.D.2.b discusses treatment costs for filtered 
system and subsection VI.D.2.c discusses treatment options for 
unfiltered systems. All non-purchased surface water and GWUDI systems 
subject to the LT2ESWTR (including filtered and unfiltered systems) 
will incur one-time costs that include time for staff training on rule 
requirements. Systems will incur monitoring costs to assess source 
water Cryptosporidium levels, though monitoring requirements vary by 
system size (large vs. small) and system type (filtered vs. 
unfiltered). A discussion of future monitoring that will occur six 
years after initial bin assignments can be found in subsection 
VI.D.2.e.
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BILLING CODE 6560-50-C
    a. Source water monitoring costs. Source water monitoring costs are 
structured on a per-plant basis. Also, as with implementation 
activities, purchased plants are assumed not to treat source water and 
will not have any monitoring costs. There are three types of monitoring 
that plants may be required to conduct--turbidity, E. coli and 
Cryptosporidium. Source water turbidity is a common water quality 
parameter used for plant operational control. Also, to meet SWTR, 
LT1ESWTR and IESWTR requirements, most water systems have turbidity 
analytical equipment in-house and operators are experienced with 
turbidity measurement. Thus, EPA assumes that the incremental turbidity 
monitoring burden associated with the LT2ESWTR is negligible.
    Filtered plants in small systems initially will be required to 
conduct one year of biweekly E. coli source water monitoring. These 
plants will be required to monitor for Cryptosporidium if, as a result 
of initial bin classification, E. coli levels exceed the following 
concentrations: (1) Annual mean  10 E. coli/100 mL for lakes 
and reservoir sources, and (2) annual mean  50 E. coli/100 
mL for flowing stream sources. EPA estimated the percent of small 
plants that would be triggered into Cryptosporidium monitoring as being 
equal to the percent of large plants that would fall into any bin 
requiring additional treatment.
    Estimates of laboratory fees, shipping costs, labor hours for 
sample collection, and hours for reporting results were used to predict 
system costs for initial source water monitoring under the LT2ESWTR. 
Table VI-9 summarizes the present value of monitoring costs for initial 
bin classification. Total present value monitoring costs for initial 
bin classification range from $46 million to $60 million depending on 
the occurrence data set and discount rate. Appendix D of the LT2ESWTR 
EA provides a full explanation of how these costs were developed (USEPA 
2003a).

[[Page 47749]]



                                  Table VI-9.--Summary of Present Value Monitoring Costs for Initial Bin Classification
                                                                   ($millions, 2000$)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                          System Size                            ICR (3%) A   ICR (7%) B   ICRSSL (3%) C   ICRSSL (7%) D   ICRSSM (3%) E   ICRSSM (7%) F
--------------------------------------------------------------------------------------------------------------------------------------------------------
<=10K.........................................................        $34.6        $29.7           $25.7           $22.2           $29.2           $25.1
10K...........................................................         25.7         24.3            25.7            24.3            25.7            24.3
                                                               --------------
    Total.....................................................         60.3         54.0            51.4            46.5            54.9           49.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Chapter 6 of the LT2ESWTR Economic Analysis (USEPA 2003a).

    b. Filtered systems treatment costs. The Agency calculated 
treatment costs by estimating the number of plants that will be adding 
treatment technologies and coupling these estimates with unit costs ($/
plant) of the selected technologies. Table VI-10 shows the number of 
plants estimated to select different treatment technologies; Table VI-
11 summarizes the present value treatment costs and annualized present 
value costs for both filtered and unfiltered systems.
    To estimate the number of filtered plants that would select a 
particular treatment technology, the Agency followed a two step 
process. First, the number of plants that must make treatment changes 
to meet the proposed LT2ESWTR requirement was determined by the binning 
process. Second, EPA predicted the treatment technologies that plants 
would choose to meet the proposed requirements. The Agency used a 
``least-cost decision tree'' as the basic framework for determining the 
treatment technology selection. In other words, EPA assumed that 
drinking water plants would select the least expensive technology or 
combination of technologies to meet the log removal requirements of a 
given action bin. However, these technology selections were constrained 
by maximum use percentages, which recognize that some plants will not 
be able to implement certain technologies because of site-specific 
conditions. In addition, certain potentially lower cost components of 
the microbial toolbox, such as changes to the plant intake, were not 
included because the Agency lacked data to estimate the number of 
plants that could select it. These limitations on technology use may 
result in an overestimate of costs. An in-depth discussion of the 
technology selection methodology and unit cost estimates can be found 
in appendices E and F of the proposed LT2ESWTR EA (USEPA 2003a).

                        Table VI-10.--Technology Selection Forecasts for Filtered Plants
----------------------------------------------------------------------------------------------------------------
                                                                                             Data set
                                                                                --------------------------------
                                                                                    ICR       ICRSSL     ICRSSM
----------------------------------------------------------------------------------------------------------------
                             Technology Selections
 
Bag Filter 1.0 Log.............................................................      1,545      1,236      1,441
Cartridge Filter 2.0 Log.......................................................        190         17         52
CL02 0.5 Log...................................................................         77         60         70
Combined Filter Performance 0.5 Log............................................         16         12         14
In-bank Filtration 1.0 Log.....................................................          5          3          4
MF/UF 2.5 Log..................................................................         10          3          5
 
                           Technology Selections \1\
 
03 0.5 Log.....................................................................         26         17         21
03 1.0 Log.....................................................................         24         18         21
03 2.0 Log.....................................................................          9          1          2
Secondary Filter 1.0 Log.......................................................          0          0          0
UV 2.5 Log.....................................................................        998        490        632
WS Control 0.5 Log.............................................................          0          0          0
    Total Plants Selecting Technologies........................................      2,893      1,852     2,255
----------------------------------------------------------------------------------------------------------------
\1\ Some plants are projected to select more than one technology to meet LT2ESWTR bin requirements;
  consequently, the value for total plants does not equal the sum of all technologies selected. Source: Chapter
  6 of the LT2ESWTR Economic Analysis (USEPA 2003a).

    c. Unfiltered systems treatment costs. The proposed LT2ESWTR 
requires all unfiltered plants to achieve 2 logs of inactivation if 
their mean source water Cryptosporidium concentration is less than or 
equal to 0.01 oocysts/L and 3 logs of inactivation if it is greater 
than 0.01 oocysts/L. For most systems, UV appears to be the least 
expensive technology that can achieve the required log inactivation of 
Cryptosporidium, and it is expected to be widely used by unfiltered 
systems to meet the rule requirement. However, as with filtered 
systems, EPA estimated that a small percentage of plants would elect to 
install a technology more expensive than UV due to the configuration of 
existing equipment or other factors. Ozone is the next least expensive 
technology that will meet the inactivation requirements for some 
systems, and is estimated to be used by plants that do not use UV.
    All unfiltered plants must meet requirements of the LT2ESWTR; 
therefore, the percent of plants adding technology is 100 percent. This 
also assumes that no unfiltered systems currently use these additional 
treatment technologies. For this cost analysis, the Agency assumed 100 
percent of very small unfiltered systems will use UV; for all other 
unfiltered system sizes, the Agency estimated that 90 percent would 
install UV and 10 percent would add ozone. This analysis is discussed 
in more detail in the LT2ESWTR EA (USEPA 2003a). Treatment costs for 
unfiltered systems are included in Table VI-11.

[[Page 47750]]



                    Table VI-11.--Total Present Value and Annualized Present Value Treatment Costs for Filtered and Unfiltered Plants
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                              Present      Present
                                                              System Size      Value        Value      Annualized   Annualized     Total        Total
                         Data Set                             (population     Capital      Capital     O&M Costs    O&M Costs   Annuallized   Annualized
                                                                served)     Costs at 3%  Costs at 7%    at 3% C      at 7% D    Costs at 3%  Costs at 7%
                                                                                 A            B                                      E            F
--------------------------------------------------------------------------------------------------------------------------------------------------------
ICR.......................................................        <=10,000        $76.1        $56.0         $5.2         $4.3         $9.6         $9.1
                                                            10,      1,092.4        868.0         26.1         22.7         88.8         97.1
                                                                       000
    TOTAL.................................................  ..............      1,168.5        924.0         31.3         26.9         98.4        106.2
                                                                           --------------
ICRSSL....................................................        <=10,000         42.8         31.5          2.9          2.4          5.3          5.1
                                                            10,        707.1        561.8         16.2         14.0         56.8         62.3
                                                                       000
    TOTAL.................................................  ..............        749.8        593.3         19.0         16.4         62.1         67.3
                                                                           --------------
ICRSSM....................................................        <=10,000         52.6         38.7          3.5          2.9          6.6          6.2
                                                            10,        842.4        669.3         19.4         16.9         67.8         74.3
                                                                       000
    TOTAL.................................................  ..............        894.9        708.0         23.0         19.8         74.4         80.6
                                                                           --------------
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Chapter 6 of the LT2ESWTR Economic Analysis (USEPA 2003a)

    d. Uncovered finished water storage facilities. As part of the 
LT2ESWTR, systems with uncovered finished water storage facilities have 
the option to cover the storage facility or provide disinfection after 
the storage facility, unless the State has determined that existing 
risk mitigation is adequate. Disinfection alternatives must achieve at 
least four logs of virus inactivation. To develop national cost 
estimates for systems to comply with this provision of the LT2ESWTR, 
unit costs for each treatment alternative and the percentage of systems 
selecting each alternative were estimated for the inventory of systems 
with uncovered finished water storage facilities. A full description of 
the unit costs and other assumptions used in this analysis is presented 
in Chapter 6 and Appendix I of the LT2ESWTR EA (USEPA 2003a).
    The Agency assumed that all systems with uncovered finished water 
storage facilities will have to either install a cover or treat their 
discharge. This overestimates the cost of this provision because States 
can determine that systems with uncovered finished storage facilities 
do not need to take these additional measures. The technology selection 
for the uncovered finished water storage facilities was developed 
through a least-cost approach.
    For systems with uncovered storage facility capacities of five 
million gallons (MG) or less, covering the storage facilities is the 
least expensive alternative. Although chlorination is the least 
expensive alternative for the remaining systems, the ability of a 
system to use booster chlorination depends on their current residual 
disinfectant type. Less than half of all surface water systems are 
predicted to use chloramination following implementation of the Stage 2 
DBPR. Adding chlorine to water that has been treated with chloramines 
is not a feasible alternative; therefore, the fraction of systems 
projected to add booster chlorination to the effluent from the storage 
facility was estimated at 50 percent, with the remaining 50 percent 
estimated to add covers. The technology selection for uncovered 
finished water storage facilities is presented in Table VI-12.

                  Table VI-12.--Estimated Technology Selection for Uncovered Storage Facilities
----------------------------------------------------------------------------------------------------------------
                                                          Number of uncovered      Floating         Booster
                  Size category (MG)                      storage facilities      cover  (%)   chlorination  (%)
----------------------------------------------------------------------------------------------------------------
0-0.1................................................                       25          100   ..................
0.1-1................................................                        7          100   ..................
1-5.......................................                       44          100   ..................
5-10......................................                       12          100   ..................
10-20.....................................                       10          100   ..................
20-40.....................................                        9           50                  50
40-60.....................................                        4           50                  50
60-80.....................................                        4           50                  50
80-100....................................                        6           50                  50
100-150...................................                        6           50                  50
150-200...................................                        2           50                  50
200-250...................................                        4           50                  50
250-1,000.................................                        4           50                  50
1,000.....................................                        1           50                 50
----------------------------------------------------------------------------------------------------------------
Source: Appendix I of the LT2ESWTR Economic Analysis (USEPA 2003a)

    Table VI-13 summarizes total annualized present value costs for the 
uncovered storage facility provision using both three and seven percent 
discount rates. The Agency estimates the total annualized present value 
cost for covering or treating uncovered finished water storage 
facilities to be approximately $5.4 million at a three percent discount 
rate and $6.4 million at a seven percent discount rate.

[[Page 47751]]



  Table VI-13.--Estimated Annualized Present Value Cost for Uncovered Finished Water Storage Facility Provision
                                                     (2000$)
----------------------------------------------------------------------------------------------------------------
                                            Annualized cost at 3%                  Annualized cost at 7%
 System size (population served)  ------------------------------------------------------------------------------
                                     Capital        O&M          Total       Capital        O&M         Total
----------------------------------------------------------------------------------------------------------------
<=10,000.........................       $3,520       $1,649       $5,169        $4,713       $1,552       $6,264
10,000................    3,349,320    2,046,425    5,395,745     4,483,927    1,925,203    6,409,129
----------------------------------
      Total......................    3,352,840    2,048,074    5,400,915     4,488,639    1,926,754   6,415,393
----------------------------------------------------------------------------------------------------------------
Source: Appendix I of the LT2ESWTR Economic Analysis (USEPA 2003a)

    e. Future monitoring costs. Six years after initial bin 
classification, filtered and unfiltered plants will be required to 
conduct a second round of monitoring to assess whether source water 
Cryptosporidium levels have changed significantly. EPA will evaluate 
new analytical methods and surrogate indicators of microbial water 
quality in the interim. While the costs of monitoring are likely to 
change in the six years following rule promulgation, it is difficult to 
predict how they will change. In the absence of any other information, 
it was assumed that the laboratory costs would be the same as for the 
initial monitoring.
    All plants that conducted initial monitoring were assumed to 
conduct the second round of monitoring as well, except for those 
systems that installed treatment that reduces 2.5 logs of 
Cryptosporidium or greater as a result of the rule. These systems are 
exempt from monitoring under the LT2ESWTR. Table VI-8 shows the number 
of systems that are estimated to conduct the second round of monitoring 
(listed as ``future'' monitoring in the table). EPA estimates the cost 
of re-binning will range from $23 million to $38 million depending on 
the occurrence data set and discount rate used in the estimate (see 
Table VI-14). Costs differ among Cryptosporidium occurrence data sets 
due to differences in estimates of the number of plants that will add 
technologies to achieve at least 2.5 log Cryptosporidium reduction and 
the number of small plants that will be triggered into monitoring for 
Cryptosporidium. Appendix D of the EA provides further details (USEPA 
2003a).

                      Table VI-14.--Present Value of Monitoring Costs of Future Re-binning
                                               [$millions, 2000$]
----------------------------------------------------------------------------------------------------------------
                                                      ICR (3%)  ICR (7%)   ICRSSL    ICRSSL    ICRSSM    ICRSSM
                                                     --------------------   (3%)      (7%)      (3%)      (7%)
                     System size                                         ---------------------------------------
                                                          A         B         C         D         E         F
----------------------------------------------------------------------------------------------------------------
<=10K...............................................     $23.5     $14.3     $18.4     $11.3     $20.7     $12.6
10k......................................      14.4       9.8      16.4      11.2      15.6      10.7
      Total.........................................      37.8      24.1      34.8      22.5      36.3     23.3
----------------------------------------------------------------------------------------------------------------
Source: Chapter 6 of the LT2ESWTR Economic Analysis (USEPA 2003a)

    f. Sensitivity analysis--influent bromide levels on technology 
selection for filtered plants. One concern about the ICR data set was 
that it may not actually reflect influent bromide levels in some plants 
during droughts. High influent bromide levels (the precursor for 
bromate formation) limits ozone use because the plant would not be able 
to meet the MCL for bromate. The Agency conducted a sensitivity 
analysis to estimate an impact of higher influent bromide levels would 
have on technology decisions. The sensitivity analysis assumes influent 
bromide concentrations of 50 parts per billion (ppb) above the ICR 
concentrations. Overall, the impact of these assumptions have a minimal 
impact on costs. A complete discussion of this sensitivity analysis is 
located in LT2ESWTR EA (USEPA 2003a).
3. State/Primacy Agency Costs
    The Agency estimates that States and primacy agencies will incur an 
annualized present value cost of $0.9 to $1.0 million using a three 
percent discount rate and $1.2 million at seven percent. State 
implementation activities include regulation adoption and program 
implementation, training State staff, training PWS staff, providing 
technical assistance to PWSs, and updating the management system. To 
estimate implementation costs to States/Primacy Agencies, the number of 
full-time employees (FTEs) per activity is multiplied by the number of 
labor hours per FTE, the cost per labor hour, and the number of States 
and Territories.
    In addition to implementation costs, States and primacy agencies 
will also incur costs associated with monitoring data management. 
Because EPA will directly manage the first round of monitoring by large 
systems (serving at least 10,000 people), States are not predicted to 
incur costs for these activities. States will, however, incur costs 
associated with small system monitoring. This is a result of the 
delayed start of small system monitoring, which will mean that some 
States will assume primacy for small system monitoring. In addition, 
States will review of the second round of monitoring results. States 
will also incur costs in reviewing technology compliance data and 
consulting with systems regarding benchmarking for systems that change 
their disinfection procedures to comply with the rule. Appendix D of 
the LT2ESWTR EA provides more information about the State and primacy 
agency cost analysis (USEPA 2003a).
4. Non-Quantified Costs
    EPA has quantified all the major costs for this rule and has 
provided uncertainty analyses to bound the over or underestimates in 
the costs. There are some costs that EPA has not quantified, however, 
because of lack of data. For example, some systems may merge with 
neighboring systems to comply with this rule. Such changes have both 
costs (legal fees and connecting infrastructure) and benefits 
(economies of scale). Likewise, systems would incur

[[Page 47752]]

costs for procuring a new source of water that may result in lower 
overall treatment costs.
    In addition, the Agency was unable to predict the usage or estimate 
the costs of several toolbox options. These options include intake 
management and demonstrations of performance. They have not been 
included in the quantified analysis because data are not available to 
estimate the number of systems that may use these toolbox options to 
comply with the LT2ESWTR. Not including these generally low-cost 
options may result in overestimation of costs.

E. What Are the Household Costs of the Proposed Rule?

    Another way to assess a rule's impact is to consider how it might 
impact residential water bills. This analysis considers the potential 
increase in a household's water bill if a CWS passed the entire cost 
increase resulting from this rule on to its customers. It is a tool to 
gauge potential impacts and should not be construed as precise 
estimates of potential changes to individual water bills.
    Included in this analysis are all CWS costs, including rule 
implementation, initial and future monitoring for bin classification, 
additional Cryptosporidium treatment, and treating or covering 
uncovered finished water storage facilities. Costs for small systems 
Cryptosporidium monitoring, additional Cryptosporidium treatment, and 
uncovered finished water storage facilities are assigned only to the 
subset of systems expected to incur them. Although implementation and 
monitoring represent relatively small, one-time costs, they have been 
included in the analysis to provide a complete distribution of the 
potential household cost. A detailed description of the derivation of 
household costs is in section 6.10 and Appendix J of the LT2ESTWR EA 
(USEPA 2003a).
    For purchased systems that are linked to larger nonpurchased 
systems, the households costs are calculated based on the unit costs of 
the larger system but included in the distribution from the size 
category of the purchased system. Households costs for these purchased 
systems are based on the household usage rates appropriate for the 
retail system and not the system selling the water. This approach for 
the purchased systems reflects the fact that although they will not 
face increased costs from adding their own treatment, whatever costs 
the wholesale utility incurs would likely be passed on as higher water 
costs.
    Table VI-15 shows the results of the household cost analysis. In 
addition to mean and median estimates, the Agency calculated the 90th 
and 95th percentile. EPA estimates that all households served by 
surface and GWUDI sources will face some increase in household costs 
due to implementation of the LT2ESWTR (except for those few served by 
systems that have already installed 5.5 logs of treatment for 
Cryptosporidium). Of all the households subject to the rule, from 24 to 
35 percent are projected to incur costs for adding treatment, depending 
on the Cryptosporidium occurrence data set used.
    Approximately 95 percent of the households potentially subject to 
the rule are served by systems serving at least 10,000 people; these 
systems experience the lowest increases in costs due to significant 
economies of scale. Over 90 percent of all households will face an 
annual cost increase of less than $5. Households served by small 
systems that install advanced technologies will face the greatest 
increases in annual costs. EPA expects that the model's projections for 
these systems are, in some cases, overstated. Some systems are likely 
to find alternative treatment techniques such as other toolbox options 
not included in this analysis, or sources of water (ground water, 
purchased water, or consolidating with another system) that would be 
less costly than installing more expensive treatment techniques.

                            Table VI-15.--Potential Annual Household Costs Impacts for the Preferred Regulatory Option (2000$)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                            Percent of      Percent of
                                                                                                                           systems with    systems with
            System: type/size               Households         Mean           Median           90th            95th          household       household
                                                                                            Percentile      Percentile     cost increase   cost increase
                                                                                                                               < $12          < $120
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                    All Systems--ICR
--------------------------------------------------------------------------------------------------------------------------------------------------------
All CWS.................................      65,816,979           $1.68           $0.13           $4.06           $7.57           98.37           99.99
CWS <= 10,000...........................       3,318,012            4.61            1.34           13.04           14.92           87.88           99.88
-----------------------------------------
                                                                   All Systems--ICRSSL
--------------------------------------------------------------------------------------------------------------------------------------------------------
All CWS.................................      65,816,979           $1.07           $0.03           $3.24           $5.43           98.31          100.00
CWS <= 10,000...........................       3,318,012            2.68            0.80            6.10            9.39           95.71           99.95
-----------------------------------------
                                                                   All Systems--ICRSSM
--------------------------------------------------------------------------------------------------------------------------------------------------------
All CWS.................................      65,816,979           $1.28           $0.03           $3.48           $6.47           99.07          100.00
CWS <= 10,000...........................       3,318,012            3.27            0.80            6.62           13.04           93.90          99.93
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: Chapter 6 of the LT2ESWTR Economic Analysis (USEPA 2003a).

F. What Are the Incremental Costs and Benefits of the Proposed 
LT2ESWTR?

    Incremental costs and benefits are those that are incurred or 
realized in reducing Cryptosporidium exposures from one alternative to 
the next. Estimates of incremental costs and benefits are useful in 
considering the economic efficiency of different regulatory options 
considered by the Agency. Generally, the goal of an incremental 
analysis is to identify the regulatory option where incremental 
benefits most closely equal incremental costs. However, the usefulness 
of this analysis is limited because many benefits from this rule are 
unquantified and not monetized. Incremental analyses should consider 
both quantified and non-quantified (where possible) benefits and costs.
    Usually an incremental analysis implies increasing levels of 
stringency along a single parameter, with each alternative providing 
all the protection of the previous alternative, plus additional 
protection. However, the

[[Page 47753]]

regulatory alternatives in this rule vary by multiple parameters (e.g, 
risk bin boundaries, treatment requirements). The comparison between 
any two alternatives is, therefore, between two separate sets of 
benefits, in the sense that they may be distributed to somewhat 
different population groups.
    The regulatory alternatives, however, do achieve increasing levels 
of benefits at increasing levels of costs. As a result, it is possible 
to display incremental net benefits from the baseline and alternative 
to alternative. Tables VI-16a and VI-16b show incremental costs, 
benefits, and net benefits for the four regulatory alternatives shown 
in Table VI-1, using the enhanced and traditional COI, respectively. 
All values are annualized present values expressed in Year 2000 
dollars. The displayed values are the mean estimates for the different 
occurrence distributions.
    With the enhanced COI, incremental costs are generally closest to 
incremental benefits for A2, a more stringent alternative than the 
Preferred Alternative, A3. For the traditional COI, incremental costs 
most closely equal incremental benefits for A3, the Preferred 
Alternative, under the majority of conditions evaluated.
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BILLING CODE 6560-50-C

G. Are There Benefits From the Reduction of Co-Occurring Contaminants?

    This section presents information on the unquantified benefits that 
will accrue from removal of other contaminants, primarily pathogens, 
due to improved control of Cryptosporidium. While the benefits analysis 
for the LT2ESWTR only includes reductions in illness and mortality 
attributable to Cryptosporidium, the LT2ESWTR is expected to reduce 
exposure to other parasitic protozoans that EPA regulates, or is 
considering for future regulation. For example, it is expected that the 
LT2ESWTR will improve control of Giardia lamblia, Cyclospora sp. and 
members of the Microsporididea class, seven genera (10 species) of 
which have been recovered in humans (Mota et al., 2000). In addition, 
greater Cryptosporidium control may improve control of the pathogenic 
bacteria and viruses. Chemical contaminants such as arsenic, DBPs and 
atrazine may also be controlled, in part, by control of 
Cryptosporidium, depending on the technologies selected.
    Giardia lamblia and Cyclospora sp. are larger than Cryptosporidium, 
while Microsporididea, bacteria, and the viruses are smaller than 
Cryptosporidium. The expected removal of co-occurring microorganisms 
can often be predicted for those treatment unit processes whose removal 
efficiency

[[Page 47755]]

depends in part, or entirely, on the size of the organism. For example, 
a study by Goodrich and Lykins (1995) evaluating bag filters showed 
that any microbe or object greater than 4.5 microns in size (the 
average size of Cryptosporidium) would be subject to removal ranging 
from 0.5 to 2.0 logs.
    Although not directly dependent on organism size, other treatment 
technologies identified in the LT2ESWTR should also provide additional 
control of co-occurring microbial pathogens. Membrane processes that 
remove Cryptosporidium are shown to achieve equivalent log removal of 
Giardia under worst-case and normal operating conditions (USEPA 2003c). 
Reduction in individual filter turbidities will reduce concentrations 
of other pathogens as well as Cryptosporidium. For example, in Dutch 
surface water, Giardia and Cryptosporidium occurrence appeared to 
correlate well with each other and for the Rhine River, with turbidity 
(Medema et al. 2001). Thus, improved control of Cryptosporidium should 
also result in improved control of Giardia lamblia.
    Some membrane technologies that might be installed to comply with 
the LT2ESWTR can also reduce or eliminate chemical contaminants 
including arsenic, DBPs and atrazine. EPA has recently finalized a rule 
to further control arsenic levels in drinking water and is concurrently 
proposing the Stage 2 DBPR to address DBP control.
    The extent to which the LT2ESWTR can reduce the overall risk from 
other contaminants has not been quantitatively evaluated because of the 
Agency's lack of data regarding the co-occurrence among Cryptosporidium 
and other microbial pathogens and contaminants. Because of the 
difficulties in establishing which systems would have multiple 
problems, such as microbial contamination, arsenic, and DBPs or any 
combination of the three, no estimate was made of the potential cost 
savings from addressing more than one contaminant simultaneously.

H. Are There Increased Risks From Other Contaminants?

    It is unlikely that the LT2ESWTR will result in a significant 
increase in risk from other contaminants. Many of the options that 
systems will select to comply with the LT2ESWTR, such as UV, improved 
filtration performance, and watershed control, do not form DBPs. Other 
technologies that are effective against Cryptosporidium, such as ozone 
and chlorine dioxide, do form DBPs. However, these DBPs are currently 
regulated under the Stage 1 DBPR, and systems will have to comply with 
these regulations when implementing technologies to meet the LT2ESWTR.

I. What Are The Effects of the Contaminant on the General Population 
and Groups Within the General Populations That Are Identified as Likely 
To Be at Greater Risk of Adverse Health Effects?

    Section II of this preamble discusses the health effects associated 
with Cryptosporidium on the general population as well as the effects 
on other sensitive sub-populations. In addition, health effects 
associated with children and pregnant women are discussed in greater 
detail in section VII.G of this preamble.

J. What Are the Uncertainties in the Baseline, Risk, Benefit, and Cost 
Estimates for the Proposed LT2ESWTR as Well as the Quality and Extent 
of the Information?

    Today's proposal models the current baseline risk from 
Cryptosporidium exposure, as well as the reduction in risk and the cost 
for various rule options. There is uncertainty in the risk calculation, 
the benefit estimate, the cost estimates, and the interaction of other 
upcoming rules. Section IV of the proposed rule considers the 
uncertainty with the risk estimates; however, a brief summary of the 
major risk uncertainties as they relate to benefit estimation is 
provided next. In addition, the LT2ESWTR EA has a more extensive 
discussion of all of the uncertainties (USEPA 2003a).
    In addition, the Agency conducted sensitivity analyses to address 
uncertainty. The sensitivity analyses focus on various occurrence, 
benefit and cost factors that may have a significant effect on the 
estimated impacts of the rule. All of these sensitivity analyses are 
explained in more detail in the EA for the LT2ESWTR (USEPA 2003a).
    One area of uncertainty is associated with the estimate of 
Cryptosporidium occurrence on a national basis. The Information 
Collection Rule plant-mean data were higher than the ICRSS medium or 
large system plant-mean data at the 90th percentile. The reasons for 
these differing results are not well understood but may stem from 
differences in the populations sampled, year-to-year variation in 
occurrence, and systematic differences in the sampling and measurement 
methods employed. These data suggest that Cryptosporidium levels are 
relatively low in most water sources, but there is a subset of sources 
with significantly higher concentrations. Additional uncertainty is 
associated with estimating finished water occurrence because the 
analysis is based on assumptions about treatment plant performance. To 
account for these uncertainties, the Agency used Monte Carlo simulation 
models that allow substantial variation in each estimate and computed 
finished water occurrence values based on statistical sampling of the 
variable estimates.
    The risk associated with finished water occurrence is of lesser 
uncertainty than is typical for many contaminants because the health 
effects are measured based on Cryptosporidium challenge studies to 
human volunteer populations. Nevertheless, there is significant 
uncertainty about the dose-response associated with Cryptosporidium 
because there exists considerable differences in infectivity among the 
various tested Cryptosporidium parvum isolates. As described in section 
III.B, the Agency accounted for these differences using Monte Carlo 
simulations that randomly sampled from infectivity distributions for 
the three tested isolates. The different simulations were designed to 
account for the limited number of challenge studies and the variability 
in the infectivity of the isolates themselves. In addition, because the 
Cryptosporidium dosing levels in the human feeding studies were above 
typical drinking water exposure levels (e.g., one oocyst), there 
remains significant uncertainty that could not be quantified into the 
analysis.
    While all of the significant costs of today's proposed rule have 
been identified by EPA, there are uncertainties about some of the 
estimates. However, the Agency explored the impact of the uncertainties 
that might have the greatest impact by conducting sensitivity analyses 
and using Monte Carlo techniques. For example, section VI.D.2.f of 
today's rule explores the impact of influent bromide levels on 
technology selection. As shown in the EA for this rule, the impact of 
higher influent bromide levels will not have a significant impact on 
the rule's costs. In addition, subsection 6.12 of the EA summarizes 
other cost uncertainties including the Agency's inability to include 
some lower cost toolbox options in the cost analysis (USEPA 2003a).
    Last, EPA has recently finalized new regulations for arsenic, 
radon, Cryptosporidium in small surface water systems, and filter 
backwash in all system sizes (LT1ESWTR and Filter Backwash Rule); 
proposed a rule for microbials in ground water systems (Ground Water 
Rule); and is

[[Page 47756]]

concurrently proposing additional control of disinfection byproducts 
(Stage 2 Disinfection Byproducts Rule). These rules may have 
overlapping impacts on some drinking water systems but the extent is 
not possible to estimate because of lack of information on co-
occurrence. However, it is possible for a system to choose treatment 
technologies that would address multiple contaminants. Therefore, while 
the total cost impact of these drinking water rules is uncertain, it is 
most likely less than the estimated total cost of all individual rules 
combined.

K. What is the Benefit/Cost Determination for the Proposed LT2ESWTR?

    The Agency has determined that the benefits of the proposed 
LT2ESWTR justify the costs. As discussed in section VI.C, the proposed 
rule provides a large reduction in endemic cryptosporidiosis illness 
and mortalities. More stringent alternatives provide greater reductions 
but at higher costs. Alternative A1 provides the greatest overall 
reduction in illnesses and mortalities but the incremental benefits 
between this option and the preferred option are relatively small while 
the incremental costs are significant. In addition, the preferred 
regulatory option, unlike option A1, specifically targets those systems 
whose source water requires higher levels of treatment.
    Tables VI-17a and VI-17b present net benefits for the four 
regulatory alternatives that were evaluated. Generally, analysis of net 
benefits is used to identify alternatives where benefits exceed costs, 
as well as the alternative that maximizes net benefits. However, as 
with the analysis of incremental net benefits discussed previously, the 
usefulness of this analysis in evaluating regulatory alternatives for 
the LT2ESWTR is limited because many benefits from this rule are un-
quantified and non-monetized. Analyses of net benefits should consider 
both quantified and non-quantified (where possible) benefits and costs.
    Also, as noted earlier, the regulatory alternatives considered for 
the LT2ESWTR vary both in the population that experiences benefits and 
costs (i.e., risk bin boundaries) and the magnitude of the benefits and 
costs (i.e., treatment requirements). Consequently, the more stringent 
regulatory alternatives provide benefits to population groups that do 
not experience any benefit under less stringent alternatives.
    As shown by Tables VI-17a and VI-17b, net benefits are positive for 
all four regulatory alternatives evaluated. With the enhanced COI 
(Table VI-17a), net benefits are highest for the Preferred Alternative, 
A3, under the majority of occurrence distributions and discount rates 
evaluated. When the traditional COI (Table VI-17b) is used, the 
Preferred Alternative has the highest net benefits at a three percent 
discount rate for the two of the occurrence distributions, the 
Information Collection Rule and ICRSSM, while the least stringent 
alternative, A4, is highest for the ICRSSL. At a seven percent discount 
rate, A4 maximizes net benefits under all occurrence distributions.

Table VI-17a.-- Mean Net Benefits by Rule Option--Enhanced COI 
($millions, 2000$)

[[Page 47757]]

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BILLING CODE 6560-50-C
    In addition to the net benefits of the proposed LT2ESWTR, the 
Agency used several other techniques to compare costs and benefits. For 
example, EPA calculated the cost of the rule per case avoided. Table 
VI-18 shows both the cost of the rule per illness avoided and cost of 
the rule per death avoided. This cost effectiveness measure is another 
way of examining the benefits and costs of the rule but should not be 
used to

[[Page 47758]]

compare alternatives because an alternative with the lowest cost per 
illness/death avoided may not result in the highest net benefits. With 
the exception of alternative A1, the rule options look favorable from a 
cost effectiveness analysis when you compare them to both the average 
cost of cryptosporidiosis illness ($745 and $245 for the two COI 
approaches) and the mean value of a death avoided--approximately $7 
million dollars. Additional information about this analysis and other 
methods of comparing benefits and costs can be found in chapter 8 to 
the LT2ESWTR EA (USEPA 2003a).

                                 Table VI-18.--Cost Per Illness or Death Avoided
----------------------------------------------------------------------------------------------------------------
                                                                              Cost per illness   Cost per death
                                                                                 avoided ($)       avoided ($
                  Data set                           Rule alternative        ------------------ millions, 2000$)
                                                                                               -----------------
                                                                                 3%       7%       3%       7%
----------------------------------------------------------------------------------------------------------------
                                              A1............................      339      244      2.5      1.8
                                              A2............................      128       93      0.9      0.7
ICR.........................................  A3--Preferred.................      107       78      0.8      0.6
                                              A4............................       62       45      0.4      0.3
---------------------------------------------
                                              A1............................    1,098      789      8.0      5.7
                                              A2............................      356      259      2.5      1.8
ICRSSL......................................  A3--Preferred.................      282      208      1.9      1.4
                                              A4............................      165      122      1.1      0.8
---------------------------------------------
                                              A1............................      631      453      4.6      3.3
                                              A2............................      213      155      1.6      1.1
ICRSSM......................................  A3--Preferred.................      170      125      1.2      0.9
                                              A4............................       99       73      0.7     0.5
----------------------------------------------------------------------------------------------------------------
Source: Chapter 8 of the LT2ESWTR Economic Analysis (USEPA 2003a)

L. Request for Comment

    The Agency requests comment on all aspects of the proposed rule's 
economic impact analysis. Specifically, EPA seeks input into the 
following issues:
    [sbull] Both of the methodologies for valuing non-fatal 
cryptosporidiosis and the use of a real income growth factor to adjust 
these estimates for the years 2008 through 2027;
    [sbull] How can the Agency fully incorporate all toolbox options 
into the economic analysis?
    [sbull] How can the Agency estimate the potential benefits from 
reduced epidemic outbreaks of cryptosporidiosis?

VII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

    Under Executive Order 12866, (58 FR 51735, October 4, 1993) the 
Agency must determine whether the regulatory action is ``significant'' 
and therefore subject to OMB review and the requirements of the 
Executive Order. The Order defines ``significant regulatory action'' as 
one that is likely to result in a rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or Tribal governments or 
communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
the Executive Order.
    Pursuant to the terms of Executive Order 12866, it has been 
determined that this rule is a ``significant regulatory action.'' As 
such, this action was submitted to OMB for review. Changes made in 
response to OMB suggestions or recommendations will be documented in 
the public record.

B. Paperwork Reduction Act

    The information collection requirements in this proposed rule have 
been submitted for approval to the Office of Management and Budget 
(OMB) under the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. The 
Information Collection Request (ICR) document prepared by EPA has been 
assigned EPA ICR number 2097.01.
    The information collected as a result of this rule will allow the 
States and EPA to determine appropriate requirements for specific 
systems, and to evaluate compliance with the rule. For the first 3 
years after LT2ESWTR promulgation, the major information requirements 
concern monitoring activities and compliance tracking. The information 
collection requirements are mandatory (part 141), and the information 
collected is not confidential.
    The estimate of annual average burden hours for the LT2ESWTR during 
the first three years following promulgation is 145,854 hours. The 
annual average cost estimate is $3.9 million for labor and $9.8 million 
per year for operation and maintenance including lab costs (which is a 
purchase of service). The burden hours per response is 1.47 hours and 
the cost per response is $138.12. The frequency of response (average 
responses per respondent) is 39, annually. The estimated number of 
likely respondents is 2,560 (the product of burden hours per response, 
frequency, and respondents does not total the annual average burden 
hours due to rounding). Note that the burden hour estimates for the 
first 3-year cycle include large system but not small system 
monitoring. Conversely, burden estimate for the second 3-year cycle 
will include small system monitoring but not large system, which will 
have been completed by then.
    Burden means the total time, effort, or financial resources 
expended by persons to generate, maintain, retain, or disclose or 
provide information to or for a Federal agency. This includes the time 
needed to review instructions; develop, acquire, install, and utilize 
technology

[[Page 47759]]

and systems for the purposes of collecting, validating, and verifying 
information, processing and maintaining information, and disclosing and 
providing information; adjust the existing ways to comply with any 
previously applicable instructions and requirements; train personnel to 
be able to respond to a collection of information; search data sources; 
complete and review the collection of information; and transmit or 
otherwise disclose the information.
    An agency may not conduct or sponsor, and a person is not required 
to respond to a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for EPA's 
regulations in 40 CFR are listed in 40 CFR part 9.
    To comment on the Agency's need for this information, the accuracy 
of the provided burden estimates, and any suggested methods for 
minimizing respondent burden, including the use of automated collection 
techniques, EPA has established a public docket for this rule, which 
includes this ICR, under Docket ID No. OW-2002-0039. Submit any 
comments related to the ICR for this proposed rule to EPA and OMB. See 
Addresses section at the beginning of this notice for where to submit 
comments to EPA. Send comments to OMB at the Office of Information and 
Regulatory Affairs, Office of Management and Budget, 725 17th Street, 
NW., Washington, DC 20503, Attention: Desk Office for EPA. Since OMB is 
required to make a decision concerning the ICR between 30 and 60 days 
after August 11, 2003, a comment to OMB is best assured of having its 
full effect if OMB receives it by September 10, 2003. The final rule 
will respond to any OMB or public comments on the information 
collection requirements contained in this proposal.

C. Regulatory Flexibility Act

    The Regulatory Flexibility Act (RFA) generally requires an agency 
to prepare a regulatory flexibility analysis for any rule subject to 
notice and comment rulemaking requirements under the Administrative 
Procedure Act or other statute unless the agency certifies that the 
rule will not have a significant economic impact on a substantial 
number of small entities. Small entities include small businesses, 
small organizations, and small governmental jurisdictions.
    The RFA provides default definitions for each type of small entity. 
It also authorizes an agency to use alternative definitions for each 
category of small entity, ``which are appropriate to the activities of 
the agency'' after proposing the alternative definition(s) in the 
Federal Register and taking comment. 5 U.S.C. secs. 601(3)-(5). In 
addition to the above, to establish an alternative small business 
definition, agencies must consult with SBA's Chief Council for 
Advocacy.
    For purposes of assessing the impacts of today's proposed rule on 
small entities, EPA considered small entities to be public water 
systems serving 10,000 or fewer persons. This is the cut-off level 
specified by Congress in the 1996 Amendments to the Safe Drinking Water 
Act for small system flexibility provisions. In accordance with the RFA 
requirements, EPA proposed using this alternative definition in the 
Federal Register, (63 FR 7620, February 13, 1998), requested public 
comment, consulted with the Small Business Administration (SBA), and 
expressed its intention to use the alternative definition for all 
future drinking water regulations in the Consumer Confidence Reports 
regulation (63 FR 44511, August 19, 1998). As stated in that final 
rule, the alternative definition is applied to this proposed 
regulation.
    After considering the economic impacts of today's proposed rule on 
small entities, I certify that this action will not have a significant 
economic impact on a substantial number of small entities. We have 
determined that 274 small systems, which are 2.32% of the 11,820 small 
systems regulated by the LT2ESWTR, will experience an impact of one 
percent or greater of average annual revenues; further, 31 systems, 
which are 0.26% of the systems regulated by this rule, will experience 
an impact of three percent or greater of average annual revenues (see 
Table VII-1).

                             Table VII-1.--Annualized Compliance Cost as a Percentage of Revenues for Small Entities ($2000)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                        Systems experiencing      Systems experiencing
                                                                                     Average annual     costs of %   costs of % of
                                                                 Number of small       estimated           their revenues            their revenues
                     Entity by system size                           systems         revenuses per   ---------------------------------------------------
                                                                    (Percent)          system ($)      Percent of   Number of    Percent of   Number of
                                                                                                         sustem      systems      systems      systems
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                A                  B            E        F=A*E            G        H=A*G
---------------------------------------------------------------
Small Governments.............................................           5,910 50          2,434,200          2.4          140          0.3           15
Small Businesses..............................................           4,846 41          2,391,978          2.4          115          0.3           13
Small Organizations...........................................            1,064 9          4,446,165          1.2           13          0.1            1
All Small Entities............................................         11,820 100          2,597,966          2.3          274          0.3          31
Note: Detail may not add due to independent rounding. Data are based on the means of the highest modeled distributions using Information Collection Rule
  occurrence data set. Costs are discounted at 3 percent, summed to present value, and annualized over 25 years. Source: Chapter 7 of the LT2ESWTR EA
  (USEPA 2003a).

    The LT2ESWTR contains provisions that will affect systems serving 
fewer than 10,000 people that use surface water or GWUDI as a source. 
In order to meet the LT2ESWTR requirements, approximately 1,382 to 
2,127 small systems would need to make capital improvements. Impacts on 
small entities are described in more detail in Chapters 6 and 7 of the 
Economic Analysis for the LT2ESWTR (USEPA 2003a). Table VII-2 shows the 
annual compliance costs of the LT2ESWTR on the small entities by system 
size and type based on a three percent discount rate (other estimates 
based on different data sets and discount rates produce lower costs). 
EPA has determined that in each size category, fewer than 20% of 
systems and fewer than 1000 systems will experience an impact of one 
percent or greater of average annual revenues (USEPA 2003a).

[[Page 47760]]



             Table VII-2.--Annual Compliance Costs for the Proposed LT2ESWTR by System Size and Type
                                               [$Millions, 2000$]
----------------------------------------------------------------------------------------------------------------
                                                      System size (population served)
             System type              ---------------------------------------------------------------    Total
                                          <100       101-500    501-1,000  1,001-3,300  3,301-10,000
----------------------------------------------------------------------------------------------------------------
Public owned.........................       $0.46       $0.88       $0.94        $2.62        $5.57       $10.37
Privately owned......................        1.00        0.71        0.22         0.31         0.36         2.60
All systems..........................        1.45        1.59        1.07         2.92         5.93        12.97
----------------------------------------------------------------------------------------------------------------
Note: Results are based on the mean of the Information Collection Rule Cryptosporidium occurrence distribution.
  Costs are annualized at a three percent discount rate.
Source: Appendix D and Q of the LT2ESWTR EA (USEPA 2003a).

    Although this proposed rule will not have a significant economic 
impact on a substantial number of small entities, EPA nonetheless has 
tried to reduce the impact of this rule on small entities. The LT2ESWTR 
contains a number of provisions to minimize the impact of the rule on 
systems generally, and on small systems in particular. The risk-
targeted approach of the LT2ESWTR will impose additional treatment 
requirements only on the subset of systems with the highest 
vulnerability to Cryptosporidium, as indicated by source water pathogen 
levels. This approach will spare the majority of systems from the cost 
of installing additional treatment. Also, development of the microbial 
toolbox under the LT2ESWTR will provide both large and small systems 
with broad flexibility in selecting cost-effective compliance options 
to meet additional treatment requirements.
    Small systems will monitor for E. coli as a screening analysis for 
source waters with low levels of fecal contamination. Cryptosporidium 
monitoring will only be required of small systems if they exceed the E. 
coli trigger value. Because E. coli analysis is much cheaper than 
Cryptosporidium analysis, the use of E. coli as a screen will 
significantly reduce monitoring costs for the majority of small 
systems. In order to allow EPA to review Cryptosporidium indicator 
relationships in large system monitoring data, small systems will not 
be required to initiate their monitoring until large system monitoring 
has been completed. This will provide small systems with additional 
time to become familiar with the rule and to prepare for monitoring and 
other compliance activities.
    Funding would be available from programs administered by EPA and 
other Federal agencies to assist small public water systems (PWSs) in 
complying with the LT2ESWTR. The Drinking Water State Revolving Fund 
(DWSRF) assists PWSs with financing the costs of infrastructure needed 
to achieve or maintain compliance with SDWA requirements. Through the 
DWSRF, EPA awards capitalization grants to States, which in turn can 
provide low-cost loans and other types of assistance to eligible PWSs. 
Loans made under the program can have interest rates between 0 percent 
and market rate and repayment terms of up to 20 years. States 
prioritize funding based on projects that address the most serious 
risks to human health and assist systems most in need. Congress 
provided $1.275 billion for the DWSRF program in fiscal year 1997, and 
has provided an additional $3.145 billion for the DWSRF program for 
fiscal years 1998 through 2001.
    The DWSRF places an emphasis on small and disadvantaged 
communities. States must provide a minimum of 15% of the available 
funds for loans to small communities. A State has the option of 
providing up to 30% of the grant awarded to the State to furnish 
additional assistance to State-defined disadvantaged communities. This 
assistance can take the form of lower interest rates, principal 
forgiveness, or negative interest rate loans. The State may also extend 
repayment terms of loans for disadvantaged communities to up to 30 
years. A State can set aside up to 2% of the grant to provide technical 
assistance to systems serving communities with populations fewer than 
10,000.
    In addition to the DWSRF, money is available from the Department of 
Agriculture's Rural Utility Service (RUS) and Housing and Urban 
Development's Community Development Block Grant (CDBG) program. RUS 
provides loans, guaranteed loans, and grants to improve, repair, or 
construct water supply and distribution systems in rural areas and 
towns of up to 10,000 people. In fiscal year 2002, RUS had over $1.5 
billion of available funds for water and environmental programs. The 
CDBG program includes direct grants to States, which in turn are 
awarded to smaller communities, rural areas, and colon as in Arizona, 
California, New Mexico, and Texas and direct grants to U.S. territories 
and trusts. The CDBG budget for fiscal year 2002 totaled over $4.3 
billion.
    Although not required by the RFA to convene a Small Business 
Advocacy Review (SBAR) Panel because EPA determined that this proposal 
would not have a significant economic impact on a substantial number of 
small entities, EPA did convene a panel to obtain advice and 
recommendations from representatives of the small entities potentially 
subject to this rule's requirements.
    Before convening the SBAR Panel, EPA consulted with a group of 24 
small entity stakeholders likely to be impacted by the LT2ESWTR and who 
were asked to serve as Small Entity Representatives (SERs) after the 
Panel was convened. The small entity stakeholders included small system 
operators, local government representatives, and representatives of 
small nonprofit organizations. The small entity stakeholders were 
provided with background information on SDWA and potential alternatives 
for the LT2ESWTR in preparation for teleconferences on January 28, 
2000, February 25, 2000, and April 7, 2000. This information package 
included data on preliminary unit costs for treatment enhancements 
under consideration.
    During these three conference calls, the information that had been 
provided to the small entity stakeholders was discussed and EPA 
responded to questions and recorded initial comments. Following the 
three calls, the small entity stakeholders were asked to provide input 
on the potential impacts of the rule from their perspective. Seven 
small entity stakeholders provided written comments on these materials.
    The SBAR Panel convened on April 25, 2000. The small entity 
stakeholders comments were provided to the SBAR Panel when it convened. 
After a teleconference between the SERs and the SBAR Panel on May 25, 
2000, the SERs were invited to provide additional

[[Page 47761]]

comments on the information provided. Seven SERs provided additional 
comments on the rule components.
    The SBAR Panel's report, Final Report of the Small Business 
Advocacy Review Panel on Stage 2 Disinfectants and Disinfection 
Byproducts Rule (Stage 2 DBPR) and Long Term 2 Enhanced Surface Water 
Treatment Rule (LT2ESWTR) (USEPA 2000f), the SERs comments on the 
LT2ESWTR, and the background information provided to the SBAR Panel and 
the SERs are available for review in the docket for today's proposal 
(http://www.epa.gov.edocket/).
    In general, the SERs who were consulted on the LT2ESWTR were 
concerned about the impact of these proposed rules on small water 
systems, the ability of small systems to acquire the technical and 
financial capability to implement requirements while maintaining 
flexibility to tailor the requirements to their needs, and the 
limitations of small systems. The SBAR Panel evaluated information and 
small-entity comments on issues related to the impact of the LT2ESWTR.
    The LT2ESWTR takes into consideration the recordkeeping and 
reporting concerns identified by the SBAR Panel and the SERs. The SBAR 
Panel recommended that EPA evaluate ways to minimize the recordkeeping 
and reporting burdens under the rule by ensuring that the States have 
appropriate capacity for rule implementation, and that EPA provide as 
much monitoring flexibility as possible to small systems. EPA believes 
that the continuity with the IESWTR and LT1ESWTR was maintained to the 
extent possible to ease the transition to the LT2ESWTR, especially for 
small systems. The LT2ESWTR builds on the protection afforded under the 
IESWTR and LT1ESWTR, while minimizing the impact on small systems by 
using a risk-targeted approach (i.e., source water monitoring) to 
identify systems that are still at risk from Cryptosporidium exposure.
    The SBAR Panel noted the concern of several SERs that flexibility 
be provided in the compliance schedule of the rule. SERs commented on 
the technical and financial limitations of some small systems, the 
significant learning curve for operators with limited experience, and 
the need to continue providing uninterrupted service as reasons why 
additional compliance time may be needed for small systems. The SBAR 
Panel encouraged EPA to keep these limitations in mind in developing 
the proposed rule and provide as much compliance flexibility to small 
systems as is allowable under SDWA.
    EPA has concluded that the proposed schedule for the LT2ESWTR 
provides sufficient time for small systems to achieve compliance. The 
schedule for small system monitoring and compliance with additional 
treatment requirements lags behind the schedule for large systems. The 
basis for the lagging schedule for small systems is that it allows EPA 
to confirm or refine the E. coli screening criteria that small systems 
will use to reduce monitoring costs. However, the lagging schedule also 
provides greater time for small systems to become knowledgeable about 
the LT2ESWTR, including the new monitoring requirements, and to become 
familiar with innovative technologies, like UV, that may be used by 
some small systems to meet additional treatment requirements.
    Some SERs emphasized that EPA needs to maintain an appropriate 
balance between control of known microbial risks through adequate 
disinfection and for the more uncertain risks that may be associated 
with DBPs. The SBAR Panel did not foresee any potential conflict 
between rules regulating control of microbial contaminants and those 
regulating DBPs. EPA also believes that today's proposal and the 
accompanying proposed Stage 2 DBPR achieve an appropriate balance 
between microbial and DBP risks. The profiling and benchmarking 
requirements described in section IV.D of this preamble will ensure 
that systems maintain protection against pathogens as they make 
treatment changes to control the formation of DBPs.
    The SBAR Panel considered a wide range of options and regulatory 
alternatives for providing small businesses with flexibility in 
complying with the LT2ESWTR. The SBAR Panel was concerned with the 
option of an across-the-board additional Cryptosporidium inactivation 
requirement because of the potential high cost to small systems and the 
uncertainty regarding the extent to which implementation of the 
LT1ESWTR will adequately address Cryptosporidium contamination at small 
systems. The SBAR Panel noted that, at the time, the Stage 2 M-DBP 
Federal Advisory Committee was exploring a targeted approach to 
Cryptosporidium control based on limited monitoring and system 
assessment, which would identify a subset of vulnerable systems to 
provide additional treatment in the range of 0.5-to 2.5-log reduction. 
Further, this approach would allow E. coli monitoring in lieu of 
Cryptosporidium monitoring as a screening device for small systems. The 
SBAR Panel was also encouraged by recent developments suggesting that 
UV is a viable, cost-effective means of fulfilling any additional 
inactivation requirements.
    The SBAR Panel recommended that, in developing any additional 
inactivation requirements based on a targeted approach, EPA carefully 
consider the potential impacts on small systems and attempt to 
structure the regulatory requirements in a way that would minimize 
burden on this group. The SBAR Panel supported E. coli as an indicator 
parameter if additional monitoring is required. The SBAR Panel further 
recommended that, among the options EPA analyzes, the Agency also 
evaluate the option of not imposing any additional Cryptosporidium 
control requirements on small systems at this time, as it considers 
various options to address microbial concerns. Under this option, EPA 
would evaluate the effects of LT1ESWTR, once implemented, and then 
consider whether to impose additional requirements during its next 6-
year review of the standard, as required by SDWA.
    EPA considered these recommendations and has concluded that 
available information on the health risk associated with 
Cryptosporidium in drinking water warrant moving forward with today's 
proposal to address higher risk systems. In developing the proposed 
LT2ESWTR, EPA has implemented the Advisory Committee's recommendations 
to minimize burden on small systems. Specifically, the risk-targeted 
treatment requirements will substantially reduce overall costs for 
small systems in comparison to requiring additional treatment by all 
systems, and the use of E. coli screening will allow most small systems 
to avoid the cost of Cryptosporidium monitoring. Consequently, the 
Agency has concluded that today's proposal achieves an appropriate 
balance between public health protection and limiting the economic 
burden imposed on small entities.
    We continue to be interested in the potential impacts of the 
proposed rule on small entities and welcome comments on issues related 
to such impacts.

D. Unfunded Mandates Reform Act

1. Summary of UMRA Requirements
    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and Tribal 
governments and the private sector. Under section 202 of UMRA,

[[Page 47762]]

EPA generally must prepare a written statement, including a cost-
benefit analysis, for proposed and final rules with ``Federal 
mandates'' that may result in expenditures to State, local and Tribal 
governments, in the aggregate, or to the private sector, of $100 
million or more in any one year. Before promulgating an EPA rule for 
which a written statement is needed, section 205 of the UMRA generally 
requires EPA to identify and consider a reasonable number of regulatory 
alternatives and adopt the least costly, most cost-effective or least 
burdensome alternative that achieves the objectives of the rule. The 
provisions of section 205 do not apply when they are inconsistent with 
applicable law. Moreover, section 205 allows EPA to adopt an 
alternative other than the least costly, most cost-effective or least 
burdensome alternative if the Administrator publishes with the final 
rule an explanation why that alternative was not adopted.
    Before EPA establishes any regulatory requirements that may 
significantly or uniquely affect small governments, including Tribal 
governments, it must have developed under section 203 of the UMRA a 
small government agency plan. The plan must provide for notifying 
potentially affected small governments, enabling officials of affected 
small governments to have meaningful and timely input in the 
development of EPA regulatory proposals with significant Federal 
intergovernmental mandates, and informing, educating, and advising 
small governments on compliance with the regulatory requirements.
2. Written Statement for Rules With Federal Mandates of $100 Million or 
More
    EPA has determined that this rule contains a Federal mandate that 
may result in expenditures of $100 million or more for State, local, 
and Tribal governments, in the aggregate, or the private sector in any 
one year. Accordingly, EPA has prepared under section 202 of the UMRA a 
written statement which is summarized in this section. Table VII-3 
illustrates the annualized public and private costs for the LT2ESWTR.

                         Table VII-3.--Public and Private Costs of the Proposed LT2ESWTR
----------------------------------------------------------------------------------------------------------------
                                                                     Range of annualized costs
                                                                        (Million $, 2000$)
                                                                 --------------------------------   Percent of
                                                                    3% Discount     7% Discount     total cost
                                                                       rate            rate
----------------------------------------------------------------------------------------------------------------
PWS Costs.......................................................      $45.7-69.0      $50.2-75.2       62.2-62.4
State Costs.....................................................         0.9-1.0         1.2-1.2         1.3-0.9
Tribal Costs....................................................         0.1-0.2         0.1-0.2         0.1-0.1
                                                                 -----------------
    Total Public Costs..........................................       46.7-70.1       51.5-76.6       63.6-63.4
    Total Private Costs.........................................       26.8-40.4       29.4-44.1       36.4-36.6
                                                                 -----------------
        Total Costs.............................................      73.5-110.5      80.9-120.7    100.0-100.0
----------------------------------------------------------------------------------------------------------------
Note: The ranges represent the ICRSSL (lowest) and Information Collection Rule (highest) modeled Cryptosporidium
  occurrence distributions. Detail may not add due to independent rounding.
Source: The LT2ESWTR Economic Analysis (USEPA 2003a).

    A more detailed description of this analysis is presented in 
Economic Analysis for the LT2ESWTR (USEPA 2003a).
    a. Authorizing legislation. As noted in section II, today's 
proposed rule is promulgated pursuant to section 1412 (b)(1)(A) of the 
Safe Drinking Water Act (SDWA), as amended in 1996, which directs EPA 
to promulgate a national primary drinking water regulation for a 
contaminant if EPA determines that the contaminant may have an adverse 
effect on the health of persons, occurs in public water systems with a 
frequency and at levels of public health concern, and regulation 
presents a meaningful opportunity for health risk reduction.
    b. Cost-benefit analysis. Section VI of this preamble discusses the 
cost and benefits associated with the LT2ESWTR. Details are presented 
in the Economic Analysis for the LT2ESTWR (USEPA 2003a). For the 
LT2ESWTR proposal, EPA quantified costs and benefits for four 
regulatory alternatives. The four alternatives are described in section 
VI. Table VII-4 summarizes the range of annual costs and benefits for 
each alternative.

                                              Table VII-4.--Annual Benefits and Costs of Rule Alternatives
                                                                       [$Million]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                           Enhanced COI     Traditional    Enahnced COI    Tradition COI
                                                             range of      COI range of      range of        range of        Range of        Range of
                 Regulatory Alternative                     annualized      annualized      annualized      annualized      annualized      annualized
                                                           benefits (3%)   benefits (3%)   benefits (7%)   benefits (7%)    costs (3%)      costs (7%)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Alternative A1..........................................      $457-1,492        $305-989      $389-1,260        $260-845            $361            $388
Alternative A2..........................................       397-1,461         268-977       338-1,243         229-834         100-134         108-145
Alternative A3..........................................       374-1,445         253-967       318-1,230         216-826          73-111          81-121
(Preferred Alternative).................................
Alternative A4..........................................       328-1,349         225-907       279-1,148         192-775           37-59          41-65
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: The LT2ESWTR Economic Analysis (USEPA 2003a).

    c. Estimates of future compliance costs and disproportionate 
budgetary effects. To meet the UMRA requirement in section 202, EPA 
analyzed future compliance costs and possible disproportionate 
budgetary effects. The Agency believes that the cost estimates, 
indicated earlier and discussed in more detail in section VI of this 
preamble,

[[Page 47763]]

accurately characterize future compliance costs of the proposed rule.
    In analyzing disproportionate impacts, the Agency considered the 
impact on (1) different regions of the United States, (2) State, local, 
and Tribal governments, (3) urban, rural and other types of 
communities, and (4) any segment of the private sector. This analysis 
is presented in section 7 of Economic Analysis for the LT2ESWTR (USEPA 
2003a).
    EPA has concluded that the LT2ESWTR will not cause a 
disproportionate budgetary effect. This rule imposes the same 
requirements on systems nationally and does not disproportionately 
affect any segment. This rule will treat similarly situated systems (in 
terms of size, water quality, available data, installed technology, and 
presence of uncovered finished storage facilities) in similar 
(proportionate) ways, without regard to geographic location, type of 
community, or segment of industry. The LT2ESWTR is a rule where 
requirements are proportionate to risk. Although some groups may have 
differing budgetary effects as a result of LT2ESWTR, those costs are 
proportional to the need for greater information (monitoring) and risk 
posed (degree of treatment required). The variation in cost between 
large and small systems is due to economies of scale (a larger system 
can distribute cost across more customers). Regions will have varying 
impacts due to the number of affected systems.
    d. Macro-economic effects. Under UMRA section 202, EPA is required 
to estimate the potential macro-economic effects of the regulation. 
These types of effects include those on productivity, economic growth, 
full employment, creation of productive jobs, and international 
competitiveness. Macro-economic effects tend to be measurable in 
nationwide econometric models only if the economic impact of the 
regulation reaches 0.25 percent to 0.5 percent of Gross Domestic 
Product (GDP). In 2000, real GDP was $9,224 billion, so a rule would 
have to cost at least $23 billion to have a measurable effect. A 
regulation with a smaller aggregate effect is unlikely to have any 
measurable impact unless it is highly focused on a particular 
geographic region or economic sector.
    The macro-economic effects on the national economy from the 
LT2ESWTR should not have a measurable effect because the total annual 
costs for the proposed option range from $73 million to $111 million 
based on median Cryptosporidium occurrence distributions from the 
ICRSSL and Information Collection Rule data sets and a discount rate of 
3 percent ($81 to $121 million at a 7 percent discount rate). These 
annualized figures will remain constant over the 25-year implementation 
period that was evaluated, while GDP will probably continue to rise. 
Thus, LT2ESWTR costs measures as a percentage of the national GDP will 
only decline over time. Costs will not be highly focused on a 
particular geographic region or sector.
    e. Summary of EPA consultation with State, local, and Tribal 
governments and their concerns. Consistent with the intergovernmental 
consultation provisions of section 204 of UMRA, EPA has already 
initiated consultations with the governmental entities affected by this 
rule. A variety of stakeholders, including small governments, were 
provided the opportunity for timely and meaningful participation in the 
regulatory development process. EPA used these opportunities to notify 
potentially affected governments of regulatory requirements being 
considered.
    The Stage 2 M-DBP Federal Advisory Committee included 
representatives from State government (Association of State Drinking 
Water Administrators, Environmental Commissioners of States), local 
government (National League of Cities), and Tribes (All Indian Pueblo 
Council (AIPC)). Government and Tribal representatives on the Advisory 
Committee were generally concerned with ensuring that drinking water 
regulations are adequately protective of public health and that any 
additional public health expenditures due to new regulations achieve 
significant risk reduction. The proposed LT2ESWTR reflects the 
consensus recommendations of the Advisory Committee, as stated in the 
Agreement in Principle (65 FR 83015, December 29, 2000). Consequently, 
EPA believes that the risk-targeted approach for additional 
Cryptosporidium treatment requirements and other provisions in today's 
proposal satisfies the concerns of the government and Tribal 
representatives on the Advisory Committee.
    As described in section VII.C of this preamble, the Agency convened 
a Small Business Advocacy Review (SBAR) Panel in accordance with the 
Regulatory Flexibility Act (RFA) as amended by the Small Business 
Regulatory Enforcement Fairness Act to address the concerns of small 
entities, including small local governments specifically. Small entity 
representatives (SERs) to the SBAR panel, including representatives of 
small local governments, were concerned about the cost of the rule, the 
technical capability of small systems to implement requirements, and 
flexibility in regulatory requirements and in the compliance schedule. 
SERs also emphasized that EPA needs to balance the control of known 
microbial risks with the risks associated with DBPs.
    Today's proposal is responsive to these concerns, as stated in 
section VII.C. The LT2ESWTR will impose costs for additional treatment 
on only the fraction of systems identified through monitoring as being 
at higher risk, and overall monitoring costs for small systems will be 
greatly reduced through use of the E. coli screening to waive small 
systems from Cryptosporidium monitoring. The microbial toolbox of 
treatment options will provide significant flexibility to systems to 
identify cost-effective solutions for meeting additional 
Cryptosporidium treatment requirements. The compliance schedule for 
small systems is delayed in relation to large systems, which will allow 
small systems additional time to become knowledgeable about and prepare 
to implement the LT2ESWTR. The intent of the proposed disinfection 
profiling provisions is to ensure that when systems make treatment 
changes to control DBP formation, they maintain protection against 
pathogens.
    EPA held a meeting on the LT2ESWTR in February 2001 with 
representatives of State and local governments. Representatives of the 
following organizations attended: Association of State Drinking Water 
Administrators (ASDWA), the National Governors' Association (NGA), the 
National Conference of State Legislatures (NCSL), the International 
City/County Management Association (ICMA), the National League of 
Cities (NLC), the County Executives of America, and health departments. 
Representatives asked questions regarding how Cryptosporidium gets into 
the water, whether EPA would add laboratory approval for 
Cryptosporidium to State certification programs, the effectiveness of 
ozone and UV, and the development of ambient water quality criteria for 
Cryptosporidium.
    EPA has largely addressed these questions in this preamble. Section 
II characterizes sources of Cryptosporidium. As described in section 
IV.K, EPA is currently carrying out a laboratory approval program for 
Cryptosporidium analyses but expects that this will be included in 
State laboratory certification programs in the future. In section 
IV.C., EPA describes the effectiveness of ozone and UV for 
Cryptosporidium inactivation and provides criteria for how these 
technologies may be used to comply with the treatment requirements in

[[Page 47764]]

today's proposal. The Agency is currently exploring the development of 
ambient water quality criteria for Cryptosporidium, but such criteria 
are not available at this time and are not included in today's 
proposal.
    In addition to the Tribal representative on the Advisory Committee, 
EPA conducted outreach and consultation with Tribal representatives on 
a number of occasions regarding the LT2ESWTR. EPA presented the 
LT2ESWTR at the following forums: the 16th Annual Consumer Conference 
of the National Indian Health Board, which included over 900 
representatives of Tribes across the nation; the annual conference of 
the National Tribal Environmental Council, at which over 100 Tribes 
were represented; and the 1999 EPA/Inter-Tribal Council of Arizona, 
which included representatives from 15 Tribes. EPA also sent the 
presentation materials used in the first two meetings and meeting 
summaries to over 500 Tribes and Tribal organizations.
    Fact sheets describing the requirements of the LT2ESWTR and 
requesting Tribal input were distributed at an annual EPA Tribal 
meeting in San Francisco and at a Native American Water Works 
Association meeting in Scottsdale, Arizona. EPA also worked through its 
Regional Indian Coordinators and the National Tribal Operations 
Committee to raise awareness of the development of the proposed rule. 
EPA mailed all Federal Tribes LT2ESWTR fact sheets in November 2000. 
The Tribal representative to the Advisory Committee also presented the 
Stage 2 Agreement in Principle prior to signature in at least one 
political forum for various Tribes not affiliated with AIPC.
    EPA held a teleconference in January 2002 with 12 Tribal 
representatives and four Regional Tribal Program Coordinators. Prior to 
the teleconference, EPA sent invitations to all Federal Tribes, along 
with a fact sheet explaining the LT2ESWTR.
    Through this consultation, Tribal representatives expressed concern 
about implementing new regulations without additional funding sources. 
However, they also stated that the LT2ESWTR would have a benefit, and 
asserted that people served by small systems should receive equivalent 
public health protection. Questions were asked regarding the impact of 
the rule (e.g., number of Tribal surface water systems) and the date 
for finalizing the rule. The Tribal representative to the M-DBP 
Advisory Committee advocated that risk mitigation plans for uncovered 
finished water storage facilities should account for cultural uses by 
Tribes.
    In response to the concerns expressed by Tribal representatives, 
EPA noted that the LT2ESWTR proposal is designed to minimize costs by 
targeting higher risk systems, and includes other provisions, described 
earlier, to reduce burden. Moreover, the projected benefits of the rule 
substantially exceed costs. EPA also explained that capital projects 
related to the rule would be eligible for Federal funding sources, such 
as the Drinking Water State Revolving Fund, due to the health risks 
associated with Cryptosporidium. The LT2ESWTR Economic Analysis (USEPA 
2003a) provides an analysis of the impact of the LT2ESWTR on Tribes. 
EPA has identified 67 Tribal water systems that would be subject to the 
LT2ESWTR.
    In addition to these direct consultations with State, local, and 
Tribal governments, EPA posted a pre-proposal draft of the LT2ESWTR 
proposal on an EPA Internet site (http://www.epa.gov/safewater/) in 
November 2001. EPA received comments on this pre-proposal draft from 
ASDWA and six States, several public water systems owned by local 
governments, as well as private water systems, laboratories, and other 
stakeholders. Among the concerns raised by commenters representing 
State and local governments were the following: early implementation of 
monitoring by large systems; flexibility for States in awarding 
treatment credits to different Cryptosporidium control technologies; 
and the added burden of the rule on systems and States.
    EPA has addressed these concerns in developing the LT2ESWTR 
proposal. As described in section IV.J, EPA is planning to directly 
implement the large system monitoring requirements that occur during 
the first 2.5 years after promulgation. The planned approach is similar 
to that used for the UCMR, including an electronic data reporting 
system for storing monitoring results and tracking compliance. With 
this approach, States will be able to access data reported by their 
systems, thereby allowing States to exercise oversight of their systems 
during early implementation if they chose. However, EPA will take 
primary responsibility for providing technical assistance to systems 
and assessing compliance with monitoring requirements.
    In regard to treatment credit for Cryptosporidium control 
technologies, the Agency has made substantial efforts to ensure that 
the criteria in today's proposal are based on the best available data. 
EPA has worked in partnership with industry and researchers to gather 
information, and proposed criteria for several microbial toolbox 
options reflect comments by the Science Advisory Board. In addition, 
today's proposal gives flexibility to States by allowing them to award 
different levels of Cryptosporidium treatment credit to their systems 
based on site-specific demonstrations.
    With respect to the burden the LT2ESWTR would place on water 
systems and States, EPA has, as described previously in this preamble, 
attempted to minimize overall costs under the proposed LT2ESWTR. This 
is achieved through risk-targeting of additional treatment 
requirements, allowing most small systems to avoid Cryptosporidium 
monitoring costs through E. coli screening, and facilitating the use of 
lower cost treatment technologies like UV.
    In summary, EPA has concluded that the proposed option for the 
LT2ESWTR is needed to provide a significant public health benefit by 
reducing exposure to Cryptosporidium. While many public water systems 
achieve adequate control of Cryptosporidium, additional treatment 
should be required for filtered systems with elevated source water 
pathogen levels and for unfiltered systems. The availability of 
improved analytical methods allows additional treatment requirements to 
be targeted to higher risk systems, and the development of technologies 
like UV makes it feasible for systems to provide additional treatment. 
The monetized benefits of today's proposal significantly exceed total 
costs, and EPA believes there will be substantial unquantified benefits 
as well.
    f. Regulatory alternatives considered. As required under section 
205 of UMRA, EPA considered several regulatory alternatives to address 
systems at risk for contamination by microbial pathogens, specifically 
including Cryptosporidium. A detailed discussion of these alternatives 
can be found in section VI of the preamble and also in the Economic 
Analysis for the LT2ESWTR (USEPA 2003a).
    g. Selection of the least costly, most cost-effective, or least 
burdensome alternative that achieves the objectives of the rule. Among 
the regulatory alternatives considered for the LT2ESWTR, as described 
in section VI, the Agency believes the proposed alternative is the most 
cost-effective that achieves the objectives of the rule. The objective 
of the LT2ESWTR is to reduce risk from Cryptosporidium and other 
pathogens in systems where current regulations do not provide 
sufficient protection.
    The Agency evaluated a less costly and less burdensome alternative.

[[Page 47765]]

However, this alternative would provide no benefit to several thousand 
consumers who, under the proposed alternative, would receive benefits 
that most likely exceed their costs, based on Agency estimates. This is 
illustrated in the LT2ESWTR Economic Analysis (USEPA 2003a). By failing 
to reduce risk for consumers where additional treatment requirements 
would be cost-effective, the less costly alternative does not appear to 
achieve the objectives of the LT2ESWTR.
    The other alternatives considered by the Agency achieve the 
objectives of the rule, but are more costly, more burdensome, and 
potentially less cost-effective. The proposed alternative targets 
additional treatment requirements to systems with the highest 
vulnerability to Cryptosporidium, and maximizes net benefits under a 
broad range of conditions (USEPA 2003a). Consequently, the Agency has 
found the proposed alternative to be the most cost-effective among 
those that achieve the objectives of the rule.
3. Impacts on Small Governments
    EPA has determined that this rule contains no regulatory 
requirements that might significantly or uniquely affect small 
governments. Thus, today's rule is not subject to the requirements of 
section 203 of UMRA. As described in section VII.C, EPA has certified 
that this proposed rule will not have a significant economic impact on 
a substantial number of small entities. Estimated annual expenditures 
by small systems for the LT2ESWTR range from $7.9 to $13.0 million at a 
3% discount rate and $8.0 to $13.0 million at a 7% discount rate. While 
the treatment requirements of the LT2ESWTR apply uniformly to both 
small and large public water systems, large systems bear a majority of 
the total costs of compliance with the rule. This is due to the fact 
that large systems treat a majority of the drinking water that 
originates from surface water sources.

E. Executive Order 13132: Federalism

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include regulations that have ``substantial direct 
effects on the States, on the relationship between the national 
government and the States, or on the distribution of power and 
responsibilities among the various levels of government.''
    Under Executive Order 13132, EPA may not issue a regulation that 
has federalism implications, that imposes substantial direct compliance 
costs, and that is not required by statute, unless the Federal 
government provides the funds necessary to pay the direct compliance 
costs incurred by State and local governments, or EPA consults with 
State and local officials early in the process of developing the 
proposed regulation.
    EPA has concluded that this proposed rule may have federalism 
implications, because it may impose substantial direct compliance costs 
on State or local governments, and the Federal government will not 
provide the funds necessary to pay those costs. The proposed rule may 
result in expenditures by State, local, and Tribal governments, in the 
aggregate of $100 million or more in any one year. Costs are estimated 
to range from $73 to $111 million at a 3 percent discount rate and $81 
to $121 million using a 7 percent discount rates based on the median 
distribution modeled from ICRSSL and Information Collection Rule 
Cryptosporidium occurrence data sets. Accordingly, EPA provides the 
following federalism summary impact statement as required by section 
6(b) of Executive Order 13132.
    EPA consulted with representatives of State and local officials 
early in the process of developing the proposed regulation to permit 
them to have meaningful and timely input into its development. Section 
VII.D.2.e describes EPA's consultation with representatives of State 
and local officials. This consultation included State and local 
government representatives on the Stage 2 M-DBP Federal Advisory 
Committee, the representatives from small local governments to the SBAR 
panel, a meeting with representatives from ASDWA, NGA, NCSL, ICMA, NLC, 
the County Executives of America, and health departments, consultation 
with Tribal governments at four meetings, and comments from State and 
local governments on a pre-proposal draft of the LT2ESWTR.
    Representatives of State and local officials were generally 
concerned with ensuring that drinking water regulations are adequately 
protective of public health and that any additional regulations achieve 
significant health benefits in return for required expenditures. They 
were specifically concerned with the burden of the proposed rule, both 
in cost and technical complexity, giving flexibility to systems and 
States, balancing the control of microbial risks and DBP risks, funding 
for implementing new regulations, equal protection for small systems, 
and early implementation of monitoring by large systems.
    EPA has concluded that the proposed LT2ESWTR is needed to reduce 
the public health risk associated with Cryptosporidium in drinking 
water. Estimated benefits for the rule are significantly higher than 
costs. Further, as described in this section and in section VII.D.2.e, 
the Agency believes that today's proposal addresses many of the 
concerns expressed by representatives of government officials.
    Under the proposed LT2ESWTR, expenditures for additional treatment 
are targeted to the fraction of systems with the highest vulnerability 
to Cryptosporidium, thereby minimizing burden for the majority of 
systems that will not be required to provide additional treatment. The 
microbial toolbox of compliance options will provide flexibility to 
systems in meeting additional treatment requirements, and States have 
the flexibility to award treatment credits based on site-specific 
demonstrations. Disinfection profiling provisions are intended to 
ensure that systems do not reduce microbial protection as they take 
steps to reduce exposures to DBPs.
    The LT2ESWTR achieves equal public health protection for small 
systems. However, the use of E. coli monitoring by small systems as a 
screening analysis to determine the need for Cryptosporidium monitoring 
will reduce monitoring costs for most small systems. Capital projects 
related to the rule would be eligible for funding from the Drinking 
Water State Revolving Fund, which includes specific funding for small 
communities. EPA is planning to support the initial monitoring by large 
systems that takes place within the first 2.5 years after promulgation. 
This will substantially reduce the burden on States associated with 
early implementation of monitoring requirements.
    In the spirit of Executive Order 13132, and consistent with EPA 
policy to promote communications between EPA and State and local 
governments, EPA specifically solicits comment on this proposed rule 
from State and local officials.

F. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments

    Executive Order 13175, entitled ``Consultation and Coordination 
with Indian Tribal Governments'' (65 FR 67249, November 9, 2000), 
requires EPA

[[Page 47766]]

to develop ``an accountable process to ensure meaningful and timely 
input by Tribal officials in the development of regulatory policies 
that have Tribal implications.'' ``Policies that have Tribal 
implications'' is defined in the Executive Order to include regulations 
that have ``substantial direct effects on one or more Indian tribes, on 
the relationship between the Federal government and the Indian tribes, 
or on the distribution of power and responsibilities between the 
Federal government and Indian tribes.''
    Under Executive Order 13175, EPA may not issue a regulation that 
has Tribal implications, that imposes substantial direct compliance 
costs, and that is not required by statute, unless the Federal 
government provides the funds necessary to pay the direct compliance 
costs incurred by Tribal governments, or EPA consults with Tribal 
officials early in the process of developing the proposed regulation 
and develops a Tribal summary impact statement.
    EPA has concluded that this proposed rule may have Tribal 
implications, because it may impose substantial direct compliance costs 
on Tribal governments, and the Federal government will not provide the 
funds necessary to pay those costs. EPA has identified 67 Tribal water 
systems serving a total population of 78,956 that may be subject to the 
LT2ESWTR. They will bear an estimated total annualized cost of $135,974 
at a 3 percent discount rate ($138,910 at 7 percent) to implement this 
rule as proposed. Estimated mean annualized cost per system ranges from 
$792 to $23,979 at a 3 percent discount rate ($844 to $26,194 at 7 
percent) depending on system size (see section 7 of the LT2ESWTR 
Economic Analysis (USEPA 2003a) for details). Accordingly, EPA provides 
the following Tribal summary impact statement as required by section 
5(b) of Executive Order 13175.
    EPA consulted with representatives of Tribal officials early in the 
process of developing this regulation to permit them to have meaningful 
and timely input into its development. Section VII.D.2.e describes 
EPA's outreach and consultation with Tribes, which included 
presentations on the LT2ESWTR at four Tribal conferences and meetings, 
mailing fact sheets and presentation materials regarding the proposal 
to Tribes on several occasions, and a teleconference with 
representatives of Tribal officials to comment on the proposed rule.
    As discussed in section VII.D.2.e, Tribal representatives stated 
that protection of public health is important regardless of the number 
of people a system is serving, and they recognized that the LT2ESWTR 
would provide a public health benefit. However, Tribal representatives 
were concerned about the availability of funding to implement the 
regulation and asked about the projected impact on Tribes (e.g., number 
of Tribal surface water systems that would be affected). Also, the 
Tribal representative to the Federal Advisory Committee was concerned 
that risk mitigation plans for uncovered finished water storage 
facilities account for cultural uses by Tribes.
    EPA has concluded that the proposed LT2ESWTR is needed to reduce 
the risk associated with Cryptosporidium in public water systems using 
surface water sources. Projected benefits for today's proposal are 
substantially greater than costs. Moreover, as described in this 
section and in section VII.D.2.e, today's proposal addresses many of 
the concerns stated by Tribal representatives.
    The LT2ESWTR will provide equivalent public health protection to 
all system sizes, including Tribal systems. By targeting additional 
treatment requirements to higher risk systems, the LT2ESWTR will 
minimize overall burden in comparison with requiring additional 
treatment by all systems. In addition, the provision in the proposal 
allowing E. coli screening to determine if Cryptosporidium monitoring 
is necessary will reduce monitoring costs for many small Tribal 
systems. (EPA notes that 66 of the 67 Tribal systems identified by the 
Agency as subject to the LT2ESWTR are small systems.) Due to the health 
risks associated with Cryptosporidium, capital expenditures needed for 
compliance with the rule will be eligible for Federal funding sources, 
specifically the Drinking Water State Revolving Fund. EPA is developing 
guidance that will address consideration of Tribal cultural uses of 
uncovered finished water storage facilities.
    In the spirit of Executive Order 13175, and consistent with EPA 
policy to promote communications between EPA and Tribal governments, 
EPA specifically solicits additional comment on this proposed rule from 
Tribal officials.

G. Executive Order 13045: Protection of Children from Environmental 
Health and Safety Risks

    Executive Order 13045: ``Protection of Children from Environmental 
Health Risks and Safety Risks'' (62 FR 19885, April 23, 1997) applies 
to any rule that: (1) Is determined to be ``economically significant'' 
as defined under Executive Order 12866, and (2) concerns an 
environmental health or safety risk that EPA has reason to believe may 
have a disproportionate effect on children. If the regulatory action 
meets both criteria, the Agency must evaluate the environmental health 
or safety effects of the planned rule on children and explain why the 
planned regulation is preferable to other potentially effective and 
reasonably feasible alternatives considered by the Agency.
    This proposed rule is subject to the Executive Order because it is 
an economically significant regulatory action as defined in Executive 
Order 12866, and we believe that the environmental health or safety 
risk addressed by this action may have a disproportionate effect on 
children. Accordingly, we have evaluated the environmental health or 
safety effects of Cryptosporidium on children. The results of this 
evaluation are contained in Cryptosporidium: Risk for Infants and 
Children (USEPA 2001d) and described in this section of this preamble. 
Further, while available information is not adequate to conduct a 
quantitative risk assessment specifically on children, EPA has assessed 
the risk associated with Cryptosporidium in drinking water for the 
general population, including children. This assessment is described in 
the Economic Analysis for the LT2ESWTR (USEPA 2003a) and is summarized 
in section VI of this preamble. Copies of these documents and 
supporting information are available in the public docket for today's 
proposal.
    Cryptosporidiosis in children is similar to adult disease (USEPA 
2001d). Diarrhea is the most common symptom. Other common symptoms in 
otherwise healthy (i.e., immunocompetent) children include anorexia, 
vomiting, abdominal pain, fever, dehydration and weight loss.
    The risk of illness and death due to cryptosporidiosis depends on 
several factors, including age, nutrition, exposure, genetic 
variability, disease and the immune status of the individual. Mortality 
resulting from diarrhea generally occurs at a greater rate among the 
very young and elderly (Gerba et al., 1996). During the 1993 Milwaukee 
drinking water outbreak, associated mortalities in children were 
reported. Also, children with laboratory-confirmed cryptosporidiosis 
were more likely to have an underlying disease that altered their 
immune status (Cicirello et al., 1997). In that study, the observed 
association between increasing age of children and increased numbers of 
laboratory-confirmed cryptosporidiosis suggested to the authors that 
the data

[[Page 47767]]

are consistent with increased tap water consumption of older children. 
However, due to data limitations, this observation could not be 
adequately analyzed. Asymptomatic infection, especially in 
underdeveloped communities, can have a substantial effect on childhood 
growth (Bern et al., 2002).
    Cryptosporidiosis appears to be more prevalent in populations, such 
as children, that may not have established immunity against the disease 
and may be in greater contact with environmentally contaminated 
surfaces (DuPont et al., 1995). In the United States, children aged one 
to four years are more likely than adults to have the disease. The most 
recent reported data on cryptosporidiosis shows the occurrence rate 
(for the year 1999) is higher in children ages one to four (3.03 
incidence rate per 100,000) than in any adult age group (CDC, 2001). 
Evidence from blood sera antibodies collected from children during the 
1993 Milwaukee outbreak suggest that children had greater levels of 
Cryptosporidium infection than predicted for the general community 
(based on the random-digit dialing telephone survey method) (McDonald 
et al., 2001).
    Data indicate a lower incidence of cryptosporidiosis infection 
during the first year of life. This is attributed to breast-fed infants 
consuming less tap water and, hence, having less exposure to 
Cryptosporidium, as well as the possibility that mothers confer short 
term immunity to their children. For example, in a survey of over 
30,000 stool sample analyses from different patients in the United 
Kingdom, the one to five year age group suffered a much higher 
infection rate than individuals less than one year of age. For children 
under one year of age, those older than six months of age showed a 
higher rate of infection than individuals aged less than six months 
(Casemore, 1990). Similarly, in the U.S., of 2,566 reported 
Cryptosporidium illnesses in 1999, 525 occurred in ages one to four 
(incidence rate of 3.03 per 100,000) compared with 58 cases in infants 
under one year (incidence rate of 1.42 per 100,000) (CDC, 2001).
    An infected child may spread the disease to other children or 
family members (Heijbel et al., 1987, Osewe et al., 1996). Millard et 
al. (1994) documented greater household secondary transmission of 
cryptosporidiosis from children than from adults to household and other 
close contacts. Children continued to shed oocysts for more than two 
weeks (mean 16.5 days) after diarrhea cessation (Tangerman et al., 
1991).
    While Cryptosporidium may have a disproportionate effect on 
children, available data are not adequate to distinctly assess the 
health risk for children resulting from Cryptosporidium-contaminated 
drinking water. In assessing risk to children when evaluating 
regulatory alternatives for the LT2ESWTR, EPA assumed the same risk for 
children as for the population as a whole.
    Section VI of this preamble presents the regulatory alternatives 
that EPA evaluated for the proposed LT2ESWTR. Among the four 
alternatives the Agency considered, three involved a risk-targeting 
approach in which additional Cryptosporidium treatment requirements are 
based on source water monitoring results. A fourth alternative involved 
additional treatment requirements for all systems.
    The alternative requiring additional treatment by all systems was 
not selected because of concerns about feasibility and because it 
imposed costs but provided few benefits to systems with high quality 
source water (i.e., relatively low Cryptosporidium risk). The three 
risk-targeting alternatives were evaluated based on several factors, 
including costs, benefits, net benefits, feasibility of implementation, 
and other specific impacts (e.g., impacts on small systems or sensitive 
subpopulations).
    The proposed alternative was recommended by the M-DBP Federal 
Advisory Committee and selected by EPA as the Preferred Regulatory 
Alternative because it was deemed feasible and provides significant 
public health benefits in terms of avoided illnesses and deaths. EPA's 
analysis of benefits and costs indicates that the proposed alternative 
ranks highly among those evaluated with respect to maximizing net 
benefits, as shown in the LT2ESWTR Economic Analysis (USEPA 2003a). 
This document is available in the docket for this action.
    The result of the LT2ESWTR will be a reduction in the risk of 
illness for the entire population, including children. Because 
available evidence indicates that children may be more vulnerable to 
cryptosporidiosis than the rest of the population, the LT2ESWTR may, 
therefore, result in greater risk reduction for children than for the 
general population.
    The public is invited to submit or identify peer-reviewed studies 
and data, of which EPA may not be aware, that assessed results of early 
life exposure to Cryptosporidium.

H. Executive Order 13211: Actions That Significantly Affect Energy 
Supply, Distribution, or Use

    This rule is not a ``significant energy action'' as defined in 
Executive Order 13211, ``Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use'' (66 FR 28355 
(May 22, 2001)) because it is not likely to have a significant adverse 
effect on the supply, distribution, or use of energy. This 
determination is based on the following analysis.
    The first consideration is whether the LT2ESWTR would adversely 
affect the supply of energy. The LT2ESWTR does not regulate power 
generation, either directly or indirectly. The public and private 
utilities that the LT2ESWTR regulates do not, as a rule, generate 
power. Further, the cost increases borne by customers of water 
utilities as a result of the LT2ESWTR are a low percentage of the total 
cost of water, except for a very few small systems that might install 
advanced technologies and then need to spread that cost over a narrow 
customer base. Therefore, the customers that are power generation 
utilities are unlikely to face any significant effects as a result of 
the LT2ESWTR. In sum, the LT2ESWTR does not regulate the supply of 
energy, does not generally regulate the utilities that supply energy, 
and is unlikely to affect significantly the customer base of energy 
suppliers. Thus, the LT2ESWTR would not translate into adverse effects 
on the supply of energy.
    The second consideration is whether the LT2ESWTR would adversely 
affect the distribution of energy. The LT2ESWTR does not regulate any 
aspect of energy distribution. The utilities that are regulated by the 
LT2ESWTR already have electrical service. As derived later in this 
section, the proposed rule is projected to increase peak electricity 
demand at water utilities by only 0.02 percent. Therefore, EPA 
estimates that the existing connections are adequate and that the 
LT2ESWTR has no discernable adverse effect on energy distribution.
    The third consideration is whether the LT2ESWTR would adversely 
affect the use of energy. Because some drinking water utilities are 
expected to add treatment technologies that use electrical power, this 
potential impact is evaluated in more detail. The analyses that 
underlay the estimation of costs for the LT2ESWTR are national in scope 
and do not identify specific plants or utilities that may install 
treatment in response to the rule. As a result, no analysis of the 
effect on specific energy suppliers is possible with the available

[[Page 47768]]

data. The approach used to estimate the impact of energy use, 
therefore, focuses on national-level impacts. The analysis estimates 
the additional energy use due to the LT2ESWTR, and compares that to the 
national levels of power generation in terms of average and peak loads.
    The first step in the analysis is to estimate the energy used by 
the technologies expected to be installed as a result of the LT2ESWTR. 
Energy use is not directly stated in Technologies and Costs for Control 
of Microbial Contaminants and Disinfection By-Products (USEPA 2003c), 
but the annual cost of energy for each technology addition or upgrade 
necessitated by the LT2ESWTR is provided. An estimate of plant-level 
energy use is derived by dividing the total energy cost per plant for a 
range of flows by an average national cost of electricity of $0.076/kWh 
(USDOE EIA, 2002). These calculations are shown in detail in Chapter 7 
of the Economic Analysis for the LT2ESWTR (USEPA 2003a). The energy use 
per plant for each flow range and technology is then multiplied by the 
number of plants predicted to install each technology in a given flow 
range. The energy requirements for each flow range are then added to 
produce a national total. No electricity use is subtracted to account 
for the technologies that may be replaced by new technologies, 
resulting in a conservative estimate of the increase in energy use. 
Results of the analysis are shown in Table VII-5 for each of the 
modeled Cryptosporidium occurrence distributions. The results range 
from an incremental national annual energy usage of 0.12 million 
megawatt-hours (mW) for the modeled Information Collection Rule 
occurrence distribution to 0.07 million mW for the modeled ICRSSL 
occurrence distribution.

                                 Table VII-5.--Total Increased Annual National Energy Usage Attributable to the LT2ESWTR
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                      ICR                             ICRSSL                          ICRSSM
                                                       -------------------------------------------------------------------------------------------------
                                                                                                                                           Total annual
                      Technology                            Plants        Total annual       Plants        Total annual       Plants          energy
                                                           selecting    energy required     selecting    energy required     selecting    required (kWh/
                                                          technology        (kWh/yr)       technology        (kWh/yr)       technology          yr)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     A               B                C               D                E               F
CIO2..................................................              77         343,297               61         268,861               70         312,036
UV....................................................             998      86,827,218              490      52,212,046              632      64,515,863
O3 (0.5 log)..........................................              26      12,524,670               19      10,328,359               21      11,467,703
O3 (1.0 log)..........................................              24      12,456,132               12       6,119,824               21      10,759,696
O3 (2.0 log)..........................................               9       7,324,561                0          35,259                2       1,787,144
MF/UF.................................................              10       5,691,144                8       4,507,577                5       2,790,401
Bag Filters...........................................           1,545       1,631,873            1,236       1,306,067            1,441       1,522,243
Cartridge Filters.....................................             190          76,793               17           6,254               52          19,686
-------------------------------------------------------
      Total...........................................           2,878     126,875,687            1,844      74,784,249            2,244      93,174,772
--------------------------------------------------------------------------------------------------------------------------------------------------------
Source: The LT2ESWTR Economic Analysis (USEPA 2003a).

    To determine if the additional energy required for systems to 
comply with the rule would have a significant adverse effect on the use 
of energy, the numbers in Table VII-5 are compared to the national 
production figures for electricity. According to the U.S. Department of 
Energy's Information Administration, electricity producers generated 
3,800 million mW of electricity in 2001 (USDOE EIA, 2002). Therefore, 
even using the highest assumed energy use for the LT2ESWTR, the rule 
when fully implemented would result in only a 0.003 percent increase in 
annual average energy use.
    In addition to average energy use, the impact at times of peak 
power demand is important. To examine whether increased energy usage 
might significantly affect the capacity margins of energy suppliers, 
their peak season generating capacity reserve was compared to an 
estimate of peak incremental power demand by water utilities.
    Both energy use and water use are highest in the summer months, so 
the most significant effects on supply would be seen then. In the 
summer of 2001, U.S. generation capacity exceeded consumption by 15 
percent, or approximately 120,000 mW (USDOE EIA 2002). Assuming around-
the-clock operation of water treatment plants, the total energy 
requirement can be divided by 8,760 hours per year to obtain an average 
power demand of 15 mW for the modeled Information Collection Rule 
occurrence distribution. A more detailed derivation of this value is 
shown in Appendix P of the Economic Analysis for the LT2ESWTR (USEPA 
2003a). Assuming that power demand is proportional to water flow 
through the plant, and that peak flow can be as high as twice the 
average daily flow during the summer months, about 30 mW could be 
needed for treatment technologies installed to comply with the 
LT2ESWTR. This is only 0.024 percent of the capacity margin available 
at peak use.
    Although EPA recognizes that not all areas have a 15 percent 
capacity margin and that this margin varies across regions and through 
time, this analysis reflects the effect of the rule on national energy 
supply, distribution, or use. While certain areas, notably California, 
have experienced shortfalls in generating capacity in the recent past, 
a peak incremental power requirement of 30 mW nationwide is not likely 
to significantly change the energy supply, distribution, or use in any 
given area. Considering this analysis, EPA has concluded that LT2ESWTR 
is not likely to have a significant adverse effect on the supply, 
distribution, or use of energy.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act (NTTAA) of 1995, Public Law 104-113, section 12(d) (15 U.S.C. 272 
note), directs EPA to use voluntary consensus standards in its 
regulatory activities unless to do so would be inconsistent with 
applicable law or otherwise impractical. Voluntary consensus standards 
are technical standards (e.g., material specifications, test methods, 
sampling procedures, and business practices) that are developed or 
adopted by voluntary consensus standard bodies. The NTTAA directs EPA 
to provide Congress, through OMB, explanations when the Agency decides 
not to use available and applicable voluntary consensus standards.

[[Page 47769]]

    The proposed rulemaking involves technical standards. EPA proposes 
to use several voluntary consensus standards (VCS) methods for 
enumerating E. coli in surface waters. These methods are listed in 
section IV.K.2, Table IV-37, and were developed or adopted by the 
following organizations: American Public Health Association in Standard 
Methods for the Examination of Water and Wastewater, 20th, 19th, and 
18th Editions, the American Society of Testing Materials in Annual Book 
of ASTM Standards--Water and Environmental Technology, and the 
Association of Analytical Chemists in Official Methods of Analysis of 
AOAC International, 16th Edition. These methods are available in the 
docket for today's proposal. EPA has concluded that these methods have 
the necessary sensitivity and specificity to meet the data quality 
objectives of the LT2ESWTR.
    The Agency conducted a search to identify potentially applicable 
voluntary consensus standards for analysis of Cryptosporidium. However, 
we identified no such standards. Therefore, EPA proposes to use the 
following methods for Cryptosporidium analysis: Method 1622: 
``Cryptosporidium in Water by Filtration/IMS/FA'' (EPA-821-R-01-026, 
April 2001) (USEPA 2001e) and Method 1623: ``Cryptosporidium and 
Giardia in Water by Filtration/IMS/FA'' (EPA 821-R-01-025, April 2001) 
(USEPA 2001f).
    EPA welcomes comments on this aspect of the proposed rulemaking 
and, specifically, invites the public to identify additional 
potentially applicable voluntary consensus standards, and to explain 
why such standards should be used in this regulation.

J. Executive Order 12898: Federal Actions To Address Environmental 
Justice in Minority Populations or Low-Income Populations

    Executive Order 12898 establishes a Federal policy for 
incorporating environmental justice into Federal agency missions by 
directing agencies to identify and address disproportionately high and 
adverse human health or environmental effects of its programs, 
policies, and activities on minority and low-income populations. The 
Agency has considered environmental justice related issues concerning 
the potential impacts of this action and consulted with minority and 
low-income stakeholders.
    Two aspects of the LT2ESWTR comply with the order that requires the 
Agency to consider environmental justice issues in the rulemaking and 
to consult with stakeholders representing a variety of economic and 
ethnic backgrounds. These are: (1) The overall nature of the rule, and 
(2) the convening of a stakeholder meeting specifically to address 
environmental justice issues.
    The Agency built on the efforts conducted during the development of 
the IESWTR to comply with Executive Order 12898. On March 12, 1998, the 
Agency held a stakeholder meeting to address various components of 
pending drinking water regulations and how they might impact sensitive 
subpopulations, minority populations, and low-income populations. This 
meeting was a continuation of stakeholder meetings that started in 1995 
to obtain input on the Agency's Drinking Water Programs. Topics 
discussed included treatment techniques, costs and benefits, data 
quality, health effects, and the regulatory process. Participants were 
national, State, Tribal, municipal, and individual stakeholders. EPA 
conducted the meeting by video conference call between eleven cities. 
The major objectives for the March 12, 1998, meeting were the 
following:

    [sbull] Solicit ideas from stakeholders on known issues concerning 
current drinking water regulatory efforts;
    [sbull] Identify key areas of concern to stakeholders; and
    [sbull] Receive suggestions from stakeholders concerning ways to 
increase representation of communities in OGWDW regulatory efforts.
    In addition, EPA developed a plain-English guide for this meeting 
to assist stakeholders in understanding the multiple and sometimes 
complex issues surrounding drinking water regulations.
    The LT2ESWTR and other drinking water regulations promulgated or 
under development are expected to have a positive effect on human 
health regardless of the social or economic status of a specific 
population. The LT2ESWTR serves to provide a similar level of drinking 
water protection to all groups. Where water systems have high 
Cryptosporidium levels, they must treat their water to achieve a 
specified level of protection. Further, to the extent that levels of 
Cryptosporidium in drinking water might be disproportionately high 
among minority or low-income populations (which is unknown), the 
LT2ESWTR will work to remove those differences. Thus, the LT2ESWTR 
meets the intent of Federal policy requiring incorporation of 
environmental justice into Federal agency missions.
    The LT2ESWTR applies uniformly to CWSs, NTNCWSs, and TNCWSs that 
use surface water or GWUDI as their source. Consequently, this rule 
provides health protection from pathogen exposure equally to all income 
and minority groups served by surface water and GWUDI systems.

K. Consultations with the Science Advisory Board, National Drinking 
Water Advisory Council, and the Secretary of Health and Human Services

    In accordance with sections 1412 (d) and (e) of SDWA, the Agency 
has consulted with the Science Advisory Board (SAB), the National 
Drinking Water Advisory Council (NDWAC), and will consult with the 
Secretary of Health and Human Services regarding the proposed LT2ESWTR 
during the public comment period. EPA charged the SAB panel with 
reviewing the following aspects of the LT2ESWTR proposal:
    [sbull] The analysis of Cryptosporidium occurrence, as described in 
Occurrence and Exposure Assessment for the LT2ESWTR (USEPA 2003b);
    [sbull] The pre- and post-LT2ESWTR Cryptosporidium risk assessment, 
as described in Economic Analysis for the LT2ESWTR (USEPA 2003a); and
    [sbull] The treatment credits for the following four microbial 
toolbox components: raw water off-stream storage, pre-sedimentation, 
lime softening, and lower finished water turbidity (described in 
section IV.C of this preamble).
    EPA met with the SAB to discuss the LT2ESWTR on June 13, 2001 
(Washington, DC), September 25-26, 2001 (teleconference), and December 
10-12, 2001 (Los Angeles, CA). Written comments from the December 2001 
meeting of the SAB addressing the occurrence analysis and risk 
assessment were generally supportive. EPA has responded to the SAB's 
recommendations for Cryptosporidium occurrence analysis in the current 
draft of Occurrence and Exposure Assessment for the LT2ESWTR (USEPA 
2003b), and EPA has addressed the SAB's comments on risk assessment in 
the current draft of Economic Analysis for the LT2ESWTR (USEPA 2003a). 
Comments from the SAB on the microbial toolbox components and the 
Agency's responses to those comments are described in section IV.C of 
this preamble.
    EPA met with the NDWAC on November 8, 2001, in Washington, DC, to 
discuss the LT2ESWTR proposal. EPA specifically requested comments from 
the NDWAC on the regulatory approach taken in the proposed microbial 
toolbox (e.g., proposal of specific design and implementation criteria 
for treatment credits). The Council was generally supportive of EPA 
establishing criteria for awarding

[[Page 47770]]

treatment credit to toolbox components, but recommended that EPA 
provide flexibility for States to address system specific situations. 
EPA believes that the demonstration of performance credit, described in 
section IV.C.17, provides this flexibility by allowing States to award 
higher or lower levels of treatment credit for microbial toolbox 
components based on site specific conditions. Minutes of the NDWAC and 
SAB meetings are in the docket for today's proposal.

L. Plain Language

    Executive Order 12866 encourages Federal agencies to write rules in 
plain language. EPA invites comments on how to make this proposed rule 
easier to understand. For example: Has EPA organized the material to 
suit commenters' needs? Are the requirements in the rule clearly 
stated? Does the rule contain technical language or jargon that is not 
clear? Would a different format (grouping and ordering of sections, use 
of headings, paragraphs) make the rule easier to understand? Could EPA 
improve clarity by adding tables, lists, or diagrams? What else could 
EPA do to make the rule easier to understand?

VIII. References

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DiGiovanni, R. Seeny, M. LeChevallier, and R. Kozik. 2002. 
Continuous monitoring for detection of infectious Cryptosporidium 
parvum oocysts in drinking water. Abstracts of the 102nd General 
Meeting of the American Society for Microbiology, Salt Lake City, 
UT, May 19-22.
Adham, S., J. Jacangelo, and J. Laine. 1995. Low pressure membranes: 
assessing integrity. J. AWWA. 83:3:62.
Adham, S., P. Gagliado, D. Smith, D. Ross, K. Gramith, and R. 
Trussell. 1998. Monitoring of reverse osmosis for virus rejection. 
Proceedings of the Water Quality Technology Conference of the 
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APHA. 1992. Standard Methods for the Examination of Water and 
Wastewater; 18th Edition. American Public Health Association, 
Washington D.C.
Arora, H., M. LeChevallier, R. Aboytes, E. Bouwer, C. O'Melia, W. 
Ball, W. Weiss, and T. Speth. 2000. Full-scale evaluation of 
riverbank filtration at three Midwest water treatment plants. 
Proceedings of the Water Quality Technology Conference, Salt Lake 
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ASTM. 2001. Standard test method for on-line measurement of 
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below 5 NTU in static mode. D-6855-03.
AWWA Committee. 1983. Deterioration of water quality in large 
distribution reservoirs (open reservoirs). AWWA Committee on Control 
of Water Quality in Transmission and Distribution Systems. J. AWWA. 
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AWWA, USEPA, AWWARF, AMWA, ASDWA, and NAWC. 2001. Partnership for 
Safe Water, Phase IV Procedures and Application Package. August.
Barwick, R.S., D.A. Levy, G.F. Craun, M.J. Beach, and R.L. Calderon. 
2000. Surveillance for waterborne-disease outbreaks--United States, 
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Battigelli, D. and M. Sobsey. 1993. The inactivation of Hepatitis A 
virus, poliovirus, and coliphage MS2 by lime softening and chlorine/
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Morgan, K. Von Alt, T. Bennett, V. Tsang, and B. Furness. 1999. 
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Cabrera, M. Verastegui, E. Black, C. Sterling, and H. Gilman. 2002. 
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Campbell, A., L. Robertson, M. Snowball, and H. Smith. 1995. 
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irradiation. Wat. Res. 29:11:2583-6.
Campbell, A. and P. Wallis. 2002. The effect of UV irradiation on 
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Casemore, D. 1990. Epidemiological aspects of human 
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CEC (Clancy Environmental Consultants). 2002. UV Disinfection of 
Cryptosporidium and MS2 coliphage in Catskill-Delaware Water. Report 
to Hazen and Sawyer.
Chalmers, R., K. Elwin, A. Thomas, and D. Joynson. 2002. Infection 
with unusual types of Cryptosporidium is not restricted to 
immunocompromised patients. J. Infectious Disease. 185:270-1.
Chappell, C., P. Okhuysen, C. Sterling, C. Wang, W. Jakubowski and 
H. Dupont. 1999. Infectivity of Cryptosporidium parvum in healthy 
adults with pre-existing anti-C. Parvum serum immunoglobulin G. Am. 
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[[Page 47774]]

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List of Subjects

40 CFR Part 141

    Environmental protection, Chemicals, Indians-lands, 
Intergovernmental relations, Radiation protection, Reporting and 
recordkeeping requirements, Water supply.

40 CFR Part 142

    Environmental protection, Administrative practice and procedure, 
Chemicals, Indians-lands, Radiation protection, Reporting and 
recordkeeping requirements, Water supply.

    Dated: July 11, 2003.
Linda J. Fisher,
Acting Administrator.
    For the reasons set forth in the preamble, title 40 chapter I of 
the Code of Federal Regulations is proposed to be amended as follows:

PART 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS

    1. The authority citation for Part 141 continues to read as 
follows:

    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.

    2. Section 141.2 is amended by adding, in alphabetical order, 
definitions for Bag filters, Bank filtration, Cartridge filters, 
Flowing stream, Lake/reservoir, Membrane filtration, Off-stream raw 
water storage, Plant intake, Presedimentation, and Two-stage lime 
softening to read as follows:


Sec.  141.2  Definitions.

* * * * *
    Bag filters are pressure-driven separation devices that remove 
particulate matter larger than 1 [mu]m using an engineered porous 
filtration media through either surface or depth filtration. Bag 
filters are typically constructed of a non-rigid, fabric filtration 
media housed in a pressure vessel in which the direction of flow is 
from the inside of the bag to outside.
    Bank filtration is a water treatment process that uses a pumping 
well to recover surface water that has naturally infiltrated into 
ground water through a river bed or bank(s). Infiltration is typically 
enhanced by the hydraulic gradient imposed by a nearby pumping water 
supply or other well(s).
* * * * *
    Cartridge filters are pressure-driven separation devices that 
remove particulate matter larger than 1 [mu]m using an engineered 
porous filtration media through either surface or depth filtration. 
Cartridge filters are typically constructed as rigid or semi-rigid, 
self-supporting filter elements housed in pressure vessels in which 
flow is from the outside of the cartridge to the inside.
* * * * *
    Flowing stream is a course of running water flowing in a definite 
channel.
* * * * *
    Lake/reservoir refers to a natural or man made basin or hollow on 
the Earth's surface in which water collects or is stored that may or 
may not have a current or single direction of flow.
* * * * *
    Membrane filtration is a pressure-driven or vacuum-driven 
separation process in which particulate matter larger than 1 [mu]m is 
rejected by an engineered barrier primarily through a size exclusion 
mechanism, and which has a measurable removal efficiency of a target 
organism that can be verified through the application of a direct 
integrity test. This definition includes the common membrane 
technologies of microfiltration (MF), ultrafiltration (UF), 
nanofiltration (NF), and reverse osmosis (RO).
* * * * *
    Off-stream raw water storage refers to an impoundment in which 
water is stored prior to treatment and from which outflow is 
controlled.
* * * * *
    Plant intake refers to the works or structures at the head of a 
conduit through which water is diverted from a source (e.g., river or 
lake) into the treatment plant.
* * * * *
    Presedimentation is a preliminary unit process used to remove 
gravel, sand and other particulate material from the source water 
through settling before it enters the main treatment plant.
* * * * *
    Two-stage lime softening refers to a process for the removal of 
hardness by the addition of lime and consisting of two distinct unit 
clarification processes in series prior to filtration.
* * * * *
    3. Appendix A to Subpart Q of part 141 is amended in section I, 
Part A by adding entry number 10:
    Subpart Q--Public Notification of Drinking Water Violations.

     Appendix A to Subpart Q of Part 141--NPDWR Violations and Other Situations Requiring Public Notice \1\
----------------------------------------------------------------------------------------------------------------
                                          MCL/MRDL/TT violations \2\          Monitoring and testing procedure
                                   ---------------------------------------               violations
                                                                          --------------------------------------
            Contaminant             Tier of public                         Tier of public
                                        notice             Citation            notice             Citation
                                       required                               required
----------------------------------------------------------------------------------------------------------------
I. Violations of National Primary
 Drinking Water Regulations
 (NPDWR) \3\:
A. Microbiological Contaminants
 

[[Page 47776]]

 
                                                  * * * * * * *
10. LT2ESWTR violations...........               2  141.720-141.729......               3  141.701-141.707;
                                                                                            141.711-141.713;
                                                                                            141.730
 
                                                 * * * * * * *
----------------------------------------------------------------------------------------------------------------
\1\Violations and other situations not listed in this table (e.g., reporting violations and failure to prepare
  Consumer Confidence Reports) do not require notice, unless otherwise determined by the primary agency. Primary
  agencies may, at their option, also require a more stringent public notice tier (e.g., Tier 1 instead of Tier
  2 or Tier 2 instead of Tier 3) for specific violations and situations listed in this Appendix, as authorized
  under Sec.   141.202(a) and Sec.   141.203(a).
\2\ MCL--Maximum contaminant level, MRDL--Maximum residual disinfectant level, TT--Treatment technique
\3\ The term Violations of National Primary Drinking Water Regulations (NPDWR) is used here to include
  violations of MCL, MRDL, treatment technique, monitoring, and testing procedure requirements.

    4. Part 141 is amended by adding a new subpart W to read as 
follows:
Subpart W--Enhanced Filtration and Disinfection for Cryptosporidium

General Requirements

141.700 Applicability.
141.701 General requirements.

Source Water Monitoring Requirements

141.702 Source water monitoring.
141.703 Sampling schedules.
141.704 Sampling locations.
141.705 Analytical methods.
141.706 Requirements for use of an approved laboratory.
141.707 Reporting source water monitoring results.
141.708 Previously collected data.
141.709 Bin classification for filtered systems.

Disinfection Profiling and Benchmarking Requirements

141.710 [Reserved]
141.711 Determination of systems required to profile.
141.712 Schedule for disinfection profiling requirements.
141.713 Developing a profile.
141.714 Requirements when making a significant change in 
disinfection practice.

Treatment Technique Requirements

141.720 Treatment requirements for filtered systems.
141.721 Treatment requirements for unfiltered systems.
141.722 Microbial toolbox options for meeting Cryptosporidium 
treatment requirements.
141.723 [Reserved]
141.724 Requirements for uncovered finished water storage 
facilities.

Requirements for Microbial Toolbox Components

141.725 Source toolbox components.
141.726 Pre-filtration treatment toolbox components.
141.727 Treatment performance toolbox components.
141.728 Additional filtration toolbox components.
141.729 Inactivation toolbox components.

Reporting and Recordkeeping Requirements

141.730 Reporting requirements.
141.731 Recordkeeping requirements.

Subpart W--Enhanced Filtration and Disinfection for Cryptosporidium

General Requirements


Sec.  141.700  Applicability.

    The requirements of this subpart apply to all subpart H systems. 
Failure to comply with any requirement of this subpart is a violation 
and requires public notification.


Sec.  141.701  General requirements.

    (a) All subpart H systems, including wholesale systems, must 
characterize their source water to determine what (if any) additional 
treatment is necessary for Cryptosporidium, unless they meet the 
criteria in either paragraph (f) or (g) of this section.
    (b) Systems serving at least 10,000 people that currently provide 
filtration or that are unfiltered and required to install filtration 
must conduct source water monitoring that includes Cryptosporidium, E. 
coli, and turbidity sampling and comply with the treatment requirements 
in Sec.  141.720.
    (c) Systems serving fewer than 10,000 people that currently provide 
filtration or that are unfiltered and required to install filtration 
must conduct source water monitoring consisting of E. coli sampling or 
sampling of an alternative indicator approved by the State. If the 
annual mean concentration of E. coli exceeds the levels specified in 
Sec.  141.702(b), or if the level of a State-approved alternate 
indicator exceeds a State-approved alternative indicator trigger level, 
systems must conduct Cryptosporidium monitoring to complete the source 
water monitoring requirements and comply with the treatment 
requirements in Sec.  141.720.
    (d) Systems that are unfiltered and meet all the filtration 
avoidance criteria of Sec.  141.71 must conduct source water monitoring 
consisting of Cryptosporidium sampling and comply with the treatment 
requirements in Sec.  141.721.
    (e) Systems must comply with the requirements in this subpart based 
on the schedule in the following table, except that systems are not 
required to conduct source water monitoring if they meet the criteria 
in paragraph (f) of this section for systems that currently provide 
filtration or that are unfiltered and required to install filtration or 
paragraph (g) of this section for systems that are unfiltered and meet 
all the filtration avoidance criteria of Sec.  141.71:

[[Page 47777]]



                      Compliance Requirements Table
------------------------------------------------------------------------
                                   Must perform . .    And comply by . .
     Systems that are . . .             .\a,b\                 .
------------------------------------------------------------------------
(1) Subpart H systems serving     (i) 24 months of    Submitting a
 =10,000 people that    source water        monthly report to
 currently provide filtration or   monitoring for      EPA no later than
 that are unfiltered and           Cryptosporidium,    ten days after
 required to install filtration.   E. coli and         the end of the
                                   turbidity at        first month
                                   least once each     following the
                                   month beginning     month when the
                                   no later than       sample is taken.
                                   [Date 6 Months
                                   After Date of
                                   Publication of
                                   Final Rule in the
                                   Federal Register].
                                  (ii) Treatment      Installing
                                   technique           treatment and
                                   implementation,     complying with
                                   if necessary.       the treatment
                                                       technique no
                                                       later than [Date
                                                       72 Months After
                                                       Date of
                                                       Publication of
                                                       Final Rule in the
                                                       Federal Register]
                                                       \c\.
(2) Subpart H systems serving     (i) 24 months of    Submitting a
 =10,000 people that    source water        monthly report to
 are unfiltered and meet the       monitoring for      EPA no later than
 filtration avoidance criteria     Cryptosporidium     ten days after
 of Sec.   141.71.                 at least once       the end of the
                                   each month          first month
                                   beginning no        following the
                                   later than [Date    month when the
                                   6 Months After      sample is taken.
                                   Date of
                                   Publication of
                                   Final Rule in the
                                   Federal Register].
                                  (ii) Treatment      Installing
                                   technique           treatment and
                                   implementation,     complying with
                                   if necessary.       the treatment
                                                       technique no
                                                       later than [Date
                                                       72 Months After
                                                       Date of
                                                       Publication of
                                                       Final rule in the
                                                       Federal Register]
                                                       \c\.
(3) Subpart H systems serving     12 months of        Submitting a
 <10,000 people that currently     source water        monthly report to
 provide filtration or that are    monitoring for E.   the State no
 unfiltered and required to        coli at least       later than ten
 install filtration and are not    once every two      days after the
 required to monitor for           weeks beginning     end of the first
 Cryptosporidium based on E.       no later than       month following
 coli or other indicator           [Date 30 Months     the month when
 monitoring results \d\.           After Date of       the sample is
                                   Publication of      taken.
                                   Final Rule in the
                                   Federal Register].
(4) Subpart H systems serving     (i) 12 months of    Submitting a
 <10,000 people that currently     source water        monthly report to
 provide filtration or that are    monitoring for E.   the State no
 unfiltered and required to        coli at least       later than ten
 install filtration and must       once every two      days after the
 perform Cryptosporidium           weeks beginning     end of the first
 monitoring based on E. coli or    no later than       month following
 other indicator monitoring        [Date 30 Months     the month when
 results \d\.                      After Date of       the sample is
                                   Publication of      taken.
                                   Final Rule in the
                                   Federal Register]
                                   and 12 months of
                                   source water
                                   monitoring for
                                   Cryptosporidium
                                   at least twice
                                   each month
                                   beginning no
                                   later than [Date
                                   48 Months After
                                   Date of
                                   Publication of
                                   Final Rule in the
                                   Federal Register].
                                  (ii) Treatment      Installing
                                   technique           treatment and
                                   implementation,     complying with
                                   if necessary.       the treatment
                                                       technique no
                                                       later than [Date
                                                       102 Months After
                                                       Date of
                                                       Publication of
                                                       Final Rule in the
                                                       Federal Register]
                                                       \c\.
(5) Subpart H systems serving     (i) 12 months of    Submitting a
 <10,000 people that are           source water        monthly report to
 unfiltered and meet the           monitoring for      the State no
 filtration avoidance criteria     Cryptosporidium     later than ten
 of Sec.   141.71.                 at least twice      days after the
                                   each month          end of the first
                                   beginning no        month following
                                   later than [Date    the month when
                                   48 Months After     the sample is
                                   Date of             taken.
                                   Publication of
                                   Final Rule in the
                                   Federal Register].
                                  (ii) Treatment      Installing
                                   technique           treatment and
                                   implementation,     complying with
                                   if necessary.       the treatment
                                                       technique no
                                                       later than [Date
                                                       102 Months After
                                                       Date of
                                                       Publication of
                                                       Final Rule in the
                                                       Federal Register]
                                                       \c\.
------------------------------------------------------------------------
\a\ Any sampling performed more frequently than required must be evenly
  distributed over the sampling period.
\b\ Systems may use data that meet the requirements in Sec.   141.708
  collected prior to the monitoring start date to substitute for an
  equivalent number of months at the end of the monitoring period.
\c\ States may allow up to an additional two years for complying with
  the treatment technique requirement for systems making capital
  improvements.
\d\ See Sec.   141.702(b) to determine if Cryptosporidium monitoring is
  required.

    (f) Systems that currently provide filtration or that are 
unfiltered and required to install filtration are not required to 
conduct source water monitoring under this subpart if the system 
currently provides or will provide a total of at least 5.5 log of 
treatment for Cryptosporidium, equivalent to meeting the treatment 
requirements of Bin 4 in Sec.  141.720. Systems must notify the State 
not later than the date the system is otherwise required to submit a 
sampling schedule for monitoring under Sec.  141.703 and must install 
and operate technologies to provide a total of at least 5.5 log of 
treatment for Cryptosporidium by the applicable date in paragraph (e) 
of this section.
    (g) Systems that are unfiltered and meet all the filtration 
avoidance criteria of Sec.  141.71 are not required to conduct source 
water monitoring under this subpart if the system currently provides or 
will provide a total of at least 3 log Cryptosporidium inactivation, 
equivalent to meeting the treatment requirements for unfiltered systems 
with a mean Cryptosporidium concentration of greater than 0.01 oocysts/
L in Sec.  141.721. Systems must notify the State not later than the 
date the system is otherwise required to submit a sampling schedule for 
monitoring under Sec.  141.703. Systems must install and operate 
technologies to provide a total of at least 3 log Cryptosporidium 
inactivation by the applicable date in paragraph (e) of this section.
    (h) Systems must comply with the uncovered finished water storage 
facility requirements in Sec.  141.724 no later than [Date 36 Months 
After Date of Publication of Final Rule in the Federal Register].

[[Page 47778]]

Source Water Monitoring Requirements


Sec.  141.702  Source water monitoring.

    (a) Systems must conduct initial source water monitoring as 
specified in Sec.  141.701(b) through (f).
    (b) Systems serving fewer than 10,000 people that provide 
filtration or that are unfiltered and required to install filtration 
must perform Cryptosporidium monitoring in accordance with Sec.  
141.701(e) if they meet any of the criteria in paragraphs (b)(1) 
through (4) of this section.
    (1) For systems using lake/reservoir sources, an annual mean E. 
coli concentration greater than 10 E. coli/100 mL, based on monitoring 
conducted under this section, unless the State approves an alternative 
indicator trigger.
    (2) For systems using flowing stream sources, an annual mean E. 
coli concentration greater than 50 E. coli/100 mL, based on monitoring 
conducted under this section, unless the State approves an alternative 
indicator trigger.
    (3) If the State approves an alternative to the indicator trigger 
in paragraph (b)(1) or (b)(2) of this section, an annual concentration 
that exceeds a State-approved trigger level, including an alternative 
E. coli level, based on monitoring conducted under this section.
    (4) The system does not conduct E. coli or other State-approved 
indicator monitoring as specified in Sec.  141.701(e).
    (c) Systems may submit Cryptosporidium data collected prior to the 
monitoring start date to meet the initial source water monitoring 
requirements of paragraphs (a) through (b) of this section. Systems may 
also use Cryptosporidium data collected prior to the monitoring start 
date to substitute for an equivalent number of months at the end of the 
monitoring period. All data submitted under this paragraph must meet 
the requirements in Sec.  141.708.
    (d) Systems must conduct a second round of source water monitoring 
in accordance with the requirements in Sec.  141.701(b) through (e) of 
this section, beginning no later than the dates specified in paragraphs 
(d)(1) through (3) of this section, unless they meet the criteria in 
either paragraph Sec.  141.701(f) or (g).
    (1) Systems that serve at least 10,000 people must begin a second 
round of source water monitoring no later than [Date 108 Months After 
Date of Publication of Final Rule in the Federal Register].
    (2) Systems serving fewer than 10,000 people that provide 
filtration or that are unfiltered and required to install filtration 
must begin a second round of source water monitoring no later than 
[Date 138 Months After Date of Publication of Final Rule in the Federal 
Register] and, if required to monitor for Cryptosporidium under 
paragraph (b) of this section, must begin Cryptosporidium monitoring no 
later than [Date 156 Months After Date of Publication of Final Rule in 
the Federal Register].
    (3) Systems serving fewer than 10,000 people that are unfiltered 
and meet the filtration avoidance requirements of Sec.  141.71 must 
begin a second round of source water monitoring no later than [Date 156 
Months After Date of Publication of Final Rule in the Federal 
Register].


Sec.  141.703  Sampling schedules.

    (a) Systems required to sample under Sec.  Sec.  141.701 through 
141.702 must submit a sampling schedule that specifies the calendar 
dates that all required samples will be taken.
    (1) Systems serving at least 10,000 people must submit their 
sampling schedule for initial source water monitoring to EPA 
electronically at [insert Internet address] no later than [Date 3 
Months After Date of Publication of Final Rule in the Federal 
Register].
    (2) Systems serving fewer than 10,000 people that are filtered or 
that are unfiltered and required to install filtration must submit a 
sampling schedule for initial source water monitoring of E. coli or an 
alternative State-approved indicator to the State no later than [Date 
27 Months After Date of Publication of Final Rule in the Federal 
Register].
    (3) Filtered systems serving fewer than 10,000 people that are 
required to conduct Cryptosporidium monitoring and unfiltered systems 
serving fewer than 10,000 people must submit a sampling schedule for 
initial source water Cryptosporidium monitoring to the State no later 
than [Date 45 Months After Date of Publication of Final Rule in the 
Federal Register].
    (4) Systems must submit a sampling schedule for the second round of 
source water monitoring to the State no later than 3 months prior to 
the date the system is required to begin the second round of monitoring 
under Sec.  141.702(d).
    (b) Systems must collect samples within two days of the dates 
indicated in their sampling schedule.
    (c) If extreme conditions or situations exist that may pose danger 
to the sample collector, or which are unforeseen or cannot be avoided 
and which cause the system to be unable to sample in the required time 
frame, the system must sample as close to the required date as feasible 
and submit an explanation for the alternative sampling date with the 
analytical results.
    (d) Systems that are unable to report a valid Cryptosporidium 
analytical result for a scheduled sampling date due to failure to 
comply with the analytical method requirements, including the quality 
control requirements in Sec.  141.705, must collect a replacement 
sample within 14 days of being notified by the laboratory or the State 
that a result cannot be reported for that date and must submit an 
explanation for the replacement sample with the analytical results.


Sec.  141.704  Sampling locations.

    (a) Unless specified otherwise in this section, systems required to 
sample under Sec. Sec.  141.701 through 141.702 must collect source 
water samples from the plant intake prior to any treatment. Where 
treatment is applied in an intake pipe such that sampling in the pipe 
prior to treatment is not feasible, systems must collect samples as 
close to the intake as is feasible, at a similar depth and distance 
from shore.
    (b) Presedimentation. Systems using a presedimentation basin must 
collect source water samples after the presedimentation basin but 
before any other treatment. Use of presedimentation basins during 
monitoring must be consistent with routine operational practice and the 
State may place reporting requirements to verify operational practices. 
Systems collecting samples after a presedimentation basin may not 
receive credit for the presedimentation basin under Sec.  141.726(a).
    (c) Raw water off-stream storage. Systems using an off-stream raw 
water storage reservoir must collect source water samples after the 
off-stream storage reservoir. Use of off-stream storage during 
monitoring must be consistent with routine operational practice and the 
State may place reporting requirements to verify operational practices.
    (d) Bank filtration. The required sampling location for systems 
using bank filtration differs depending on whether the bank filtered 
water is treated by subsequent filtration for compliance with Sec.  
141.173(b) or Sec.  141.552(a), as applicable.
    (1) Systems using bank filtered water that is treated by subsequent 
filtration for compliance with Sec.  141.173(b) or Sec.  141.552(a), as 
applicable, must collect source water samples from the well (i.e., 
after bank filtration), but before any other treatment. Use of bank 
filtration during monitoring must be consistent with routine 
operational practice and the State may place reporting

[[Page 47779]]

requirements to verify operational practices. Systems collecting 
samples after a bank filtration process may not receive credit for the 
bank filtration under Sec.  141.726(c).
    (2) Systems using bank filtration as an alternative filtration 
demonstration to meet their Cryptosporidium removal requirements under 
Sec.  141.173(b) or Sec.  141.552(a), as applicable, must collect 
source water samples in the surface water (i.e., prior to bank 
filtration).
    (3) Systems using a ground water source under the direct influence 
of surface water that meet all the criteria for avoiding filtration in 
Sec.  141.71 and that do not provide filtration treatment must collect 
source water samples from the ground water (e.g., the well).
    (e) Multiple sources. Systems with plants that use multiple water 
sources at the same time, including multiple surface water sources and 
blended surface water and ground water sources, must collect samples as 
specified in paragraph (e)(1) or (2) of this section. The use of 
multiple sources during monitoring must be consistent with routine 
operational practice and the State may place reporting requirements to 
verify operational practices.
    (1) If a sampling tap is available where the sources are combined 
prior to treatment, the sample must be collected from the tap.
    (2) If there is not a sampling tap where the sources are combined 
prior to treatment, systems must collect samples at each source near 
the intake on the same day and must follow either paragraph (e)(2)(i) 
or (e)(2)(ii) of this section for sample analysis.
    (i) Composite samples from each source into one sample prior to 
analysis. In the composite, the volume of sample from each source must 
be weighted according to the proportion of the source in the total 
plant flow at the time the sample is collected.
    (ii) Analyze samples from each source separately as specified in 
Sec.  141.705, and calculate a weighted average of the analysis results 
for each sampling date. The weighted average must be calculated by 
multiplying the analysis result for each source by the fraction the 
source contributed to total plant flow at the time the sample was 
collected, and then summing these values.


Sec.  141.705  Analytical methods.

    (a) Cryptosporidium. Systems must use Method 1622 Cryptosporidium 
in Water by Filtration/IMS/FA, EPA 821-R-01-026, April 2001, or Method 
1623 Cryptosporidium and Giardia in Water by Filtration/IMS/FA, EPA 
821-R-01-025, April 2001, for Cryptosporidium analysis.
    (1) Systems are required to analyze at least a 10 L sample or a 
packed pellet volume of at least 2 mL as generated by the methods 
listed in paragraph (a) of this section. Systems unable to process a 10 
L sample must analyze as much sample volume as can be filtered by two 
filters approved by EPA for the methods listed in paragraph (a) of this 
section, up to a packed pellet volume of 2 mL.
    (2)(i) Matrix spikes (MS) samples as required by the methods in 
paragraph (a) of this section must be spiked and filtered by a 
laboratory approved for Cryptosporidium analysis under Sec.  141.706. 
The volume of the MS sample must be within 10 percent of the volume of 
the unspiked sample that is collected at the same time, and the samples 
must be collected by splitting the sample stream or collecting the 
samples sequentially. The MS sample and the associated unspiked sample 
must be analyzed by the same procedure.
    (ii) If the volume of the MS sample is greater than 10 L, the 
system is permitted to filter all but 10 L of the MS sample in the 
field, and ship the filtered sample and the remaining 10 L of source 
water to the laboratory. In this case, the laboratory must spike the 
remaining 10 L of water and filter it through the filter used to 
collect the balance of the sample in the field.
    (3) Each sample batch must meet the quality control criteria for 
the methods listed in paragraph (a) of this section. Flow cytometer-
counted spiking suspensions must be used for MS samples and ongoing 
precision and recovery (OPR) samples; recovery for OPR samples must be 
11% to 100%; for each method blank, oocysts must not be detected.
    (4) Total Cryptosporidium oocysts as detected by fluorescein 
isothiocyanate (FITC) must be reported as determined by the color 
(apple green or alternative stain color approved under Sec.  141.706(a) 
for the laboratory), size (4-6 [mu]m) and shape (round to oval). This 
total includes all of the oocysts identified, less any atypical 
organisms identified by FITC, differential interference contrast (DIC) 
or 4',6-diamindino-2-phenylindole (DAPI), including those possessing 
spikes, stalks, appendages, pores, one or two large nuclei filling the 
cell, red fluorescing chloroplasts, crystals, and spores.
    (b) E. coli. Systems must use the following methods listed in this 
paragraph for enumeration of E. coli in source water (table will be 
replaced with CFR cite from Guidelines Establishing Test Procedures for 
the Analysis of Pollutants; Analytical Methods for Biological 
Pollutants in Ambient Water when finalized--expected 2003):

                                                           Methods for E. coli Enumeration \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                  VCSB methods
              Technique                      Method \1\                  EPA          ------------------------------------------------------------------
                                                                                             Standard methods                 ASTM               AOAC
--------------------------------------------------------------------------------------------------------------------------------------------------------
Most Probable Number (MPN)..........  LTB, EC-MUG............  ......................  9221B.1/9221F
                                      ONPG-MUG...............  ......................  9223B                         ......................       991.15
                                      ONPG-MUG...............  ......................  9223B
Membrane Filter (MF)................  mFCNA-MUG.....  ......................  9222D/9222G
                                      ENDONA-MUG....  ......................  9222B/9222G
                                      mTEC agar..............  1103.1................  9213D                         D5392-93
                                      Modified mTEC agar.....  Modified 1103.1
                                      MI agar................  EPA-600-R-013
                                      m-ColiBlue24 broth
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Tests must be conducted in a format that provides organism enumeration.

    XXXXXXXXXXXXXXXXXXXXXX(1) The time from sample collection to 
initiation of analysis may not exceed 24 hours. Systems must maintain 
samples between 0[deg]C and 10[deg]C during transit.
    (2) [Reserved]
    (c) Turbidity. Systems must use methods for turbidity measurement 
approved in Sec.  141.74.

[[Page 47780]]

Sec.  141.706  Requirements for use of an approved laboratory.

    (a) Cryptosporidium. Systems must have Cryptosporidium samples 
analyzed by a laboratory that has passed a quality assurance evaluation 
under EPA's Laboratory Quality Assurance Evaluation Program for 
Analysis of Cryptosporidium in Water or a laboratory that has been 
certified for Cryptosporidium analysis by an equivalent State 
laboratory certification program.
    (b) E. coli. Any laboratory certified by the EPA, the National 
Environmental Laboratory Accreditation Conference or the State for 
total coliform or fecal coliform analysis in source water under Sec.  
141.74 is deemed approved for E. coli analysis under this subpart when 
the laboratory uses the same technique for E. coli that the laboratory 
uses for source water in Sec.  141.74.
    (c) Turbidity. Measurements of turbidity must be made by a party 
approved by the State.


Sec.  141.707  Reporting source water monitoring results.

    (a) All systems serving at least 10,000 people must submit the 
results of all initial source water monitoring required under Sec.  
141.702(a) to EPA electronically at [insert Internet address]. Systems 
that do not have the ability to submit data electronically may use an 
alternative format approved by EPA.
    (b) Systems serving fewer than 10,000 people must submit the 
results of all initial source water monitoring required under Sec.  
141.702(a)-(b) to the State.
    (c) All systems must submit the results from the second round of 
source water monitoring required under Sec.  141.702(d) to the State.
    (d) Source water monitoring analysis results must be submitted not 
later than ten days after the end of first month following the month 
when the sample is collected. The submission must include the 
applicable information in paragraphs (e)(1) and (2) of this section.
    (e)(1) Systems must report the following data elements for each 
Cryptosporidium analysis:

(i) PWS ID
(ii) Facility ID
(iii) Sample collection point
(iv) Sample collection date
(v) Sample type (field or matrix spike)
(vi) Sample volume filtered (L), to nearest \1/4\ L
(vii) Was 100% of filtered volume examined
(viii) Number of oocysts counted
    (i) For matrix spike samples, systems must also report the sample 
volume spiked and estimated number of oocysts spiked. These data are 
not required for field samples.
    (ii) For samples in which less than 10 L is filtered or less than 
100% of the sample volume is examined, systems must also report the 
number of filters used and the packed pellet volume.
    (iii) For samples in which less than 100% of sample volume is 
examined, systems must also report the volume of resuspended 
concentrate and volume of this resuspension processed through 
immunomagnetic separation.
    (2) Systems must report the following data elements for each E. 
coli analysis:

(i) PWS ID
(ii) Facility ID
(iii) Sample collection point
(iv) Sample collection date
(v) Analytical method number
(vi) Method type
(vii) Source type
(viii) E. coli/100 mL
(ix) Turbidity (Systems serving fewer than 10,000 people that are not 
required to monitor for turbidity under Sec.  141.701(c) are not 
required to report turbidity with their E. coli results.)


Sec.  141.708  Previously collected data.

    (a) Systems may comply with the initial monitoring requirements of 
Sec.  141.702(a) using Cryptosporidium data collected before the system 
is required to begin monitoring if the system meets the conditions in 
paragraphs (b) through (h) of this section and EPA notifies the system 
that the data are acceptable.
    (b) To be accepted, previously collected Cryptosporidium data must 
meet the conditions in paragraphs (b)(1) through (5) of this section.
    (1) Samples were analyzed by laboratories using one of the 
analytical methods in paragraphs (b)(1)(i) through (iv) of this 
section.
    (i) Method 1623: Cryptosporidium and Giardia in Water by 
Filtration/IMS/FA, 2001, EPA-821-R-01-025.
    (ii) Method 1622: Cryptosporidium in Water by Filtration/IMS/FA, 
2001, EPA-821-R-01-026.
    (iii) Method 1623: Cryptosporidium and Giardia in Water by 
Filtration/IMS/FA, 1999, EPA-821-R-99-006.
    (iv) Method 1622: Cryptosporidium in Water by Filtration/IMS/FA, 
1999, EPA-821-R-99-001.
    (2) Samples were collected no less frequently than each calendar 
month on a regular schedule, beginning no earlier than January 1999.
    (3) Samples were collected in equal intervals of time over the 
entire collection period (e.g., weekly, monthly). Sample collection 
interval may vary for the conditions specified in Sec.  141.703(c) and 
(d) if the system provides documentation of the condition.
    (4) Samples met the conditions for sampling location specified in 
Sec.  141.704. The system must report the use of bank filtration, 
presedimentation, and raw water off-stream storage during sampling.
    (5) For each sample, the laboratory analyzed at least 10 L of 
sample or at least 2 mL of packed pellet or as much volume as could be 
filtered by 2 filters approved by EPA for the methods listed in 
paragraph (b)(1) of this section, up to a packed pellet volume of 2 mL.
    (c) The system must submit a letter to EPA concurrent with the 
submission of previously collected data certifying that the data meet 
the conditions in paragraphs (c)(1) and (2) of this section.
    (1) The reported Cryptosporidium analysis results include all 
results generated by the system during the time period beginning with 
the first reported result and ending with the final reported result. 
This applies to samples that were collected from the sampling location 
specified for source water monitoring under this subpart, not spiked, 
and analyzed using the laboratory's routine process for the analytical 
methods listed in paragraph (a)(1) of this section.
    (2) The samples were representative of a plant's source water(s) 
and the source water(s) have not changed.
    (d) For each sample, the system must report the data elements in 
Sec.  141.707(e)(1).
    (e) The laboratory or laboratories that generated the data must 
submit a letter to EPA concurrent with the submission of previously 
collected data certifying that the quality control criteria specified 
in the methods listed in paragraph (b)(1) of this section were met for 
each sample batch associated with the previously collected data. 
Alternatively, the laboratory may provide bench sheets and sample 
examination report forms for each field, matrix spike, IPR, OPR, and 
method blank sample associated with the previously collected data.
    (f) If a system has at least two years of Cryptosporidium data 
collected before [Date of Publication of Final Rule in the Federal 
Register] and the system intends to use these data to comply with the 
initial source water monitoring required under Sec.  141.702(a) in lieu 
of conducting new monitoring, the system must submit to EPA, no later 
than [Date 2 Months After Date of Publication of Final Rule in the 
Federal Register], the previously collected data and the supporting 
information specified in this section. EPA will notify the system by 
[Date 4 Months After Date of Publication of Final Rule in the Federal 
Register] as to whether the data are acceptable. If EPA does not notify 
the system that the

[[Page 47781]]

submitted data are acceptable, the system must carry out initial source 
water as specified in Sec.  Sec.  141.701 through 141.707 until EPA 
notifies the system that it has at least two years of acceptable data.
    (g) If a system has fewer than two years of Cryptosporidium data 
collected before [Date of Publication of Final Rule in the Federal 
Register] and the system intends to use these data to meet, in part, 
the initial source water monitoring required under Sec.  141.702(a), 
the system must submit to EPA, no later than [Date 8 Months After Date 
of Publication of Final Rule in the Federal Register], the previously 
collected data and the supporting information specified in this 
section. The system must carry out initial source water monitoring 
according to the requirements in Sec. Sec.  141.701 through 141.707 
until EPA notifies the system that it has at least two years of 
acceptable data.
    (h) If a system has two or more years of previously collected data 
and the system intends to use these data to comply with the initial 
source water monitoring required under Sec.  141.702(a), but the system 
also intends to carry out additional initial source water monitoring in 
order to base its determination of average Cryptosporidium 
concentration under Sec.  141.709 or Sec.  141.721 on more than two 
years of monitoring data, the system must submit to EPA, no later than 
[Date 8 Months After Date of Publication of Final Rule in the Federal 
Register], the previously collected data and the supporting information 
specified in this section. The system must carry out initial source 
water monitoring according to the requirements in Sec.  Sec.  141.701 
through 141.707 until EPA notifies the system that it has at least two 
years of acceptable data.


Sec.  141.709  Bin classification for filtered systems.

    (a) Following completion of the initial source water monitoring 
required under Sec.  141.702(a), filtered systems and unfiltered 
systems that are required to install filtration must calculate their 
initial Cryptosporidium bin concentration using the Cryptosporidium 
results reported under Sec.  141.702(a), along with any previously 
collected data that satisfy the requirements of Sec.  141.708, and 
following the procedures in paragraphs (b)(1) through (3) of this 
section.
    (b)(1) For systems that collect a total of at least 48 samples, the 
Cryptosporidium bin concentration is equal to the arithmetic mean of 
all sample concentrations.
    (2) For systems that serve at least 10,000 people and collect a 
total of at least 24 samples, but not more than 47 samples, the 
Cryptosporidium bin concentration is equal to the highest arithmetic 
mean of all sample concentrations in any 12 consecutive months during 
which Cryptosporidium samples were collected.
    (3) For systems that serve fewer than 10,000 people and take at 
least 24 samples, the Cryptosporidium bin concentration is equal to the 
arithmetic mean of all sample concentrations.
    (c) Filtered systems and unfiltered systems that are required to 
install filtration must determine their initial bin classification from 
the following table and using the Cryptosporidium bin concentration 
calculated under paragraph (a) of this section:

              Bin Classification Table for Filtered Systems
------------------------------------------------------------------------
                                         With a
                                  Cryptosporidium bin       The bin
      For systems that are:        concentration of .  classification is
                                         . .\1\              . . .
------------------------------------------------------------------------
* * * required to monitor for     Cryptosporidium <    Bin 1
 Crypto[chyph]sporidium under      0.075 oocyst/L.
 Sec.  Sec.   141.701 to 141.702.
                                  0.075 oocysts/L      Bin 2
                                   <=Cryptosporidium
                                   < 1.0 oocysts/L.
                                  1.0 oocysts/L <=     Bin 3
                                   Cryptosporidium <
                                   3.0 oocysts/L.
                                  Cryptosporidium = 3.0
                                   oocysts/L.
* * * serving fewer than 10,000   NA.................  Bin 1
 people and NOT required to
 monitor for Cryptosporidium
 under Sec.   142.702(b).
------------------------------------------------------------------------
\1\ Based on calculations in paragraph (a) or (d) of this section, as
  applicable.

    (d) Following completion of the second round of source water 
monitoring required under Sec.  141.702(d), filtered systems and 
unfiltered systems that are required to install filtration must 
recalculate their Cryptosporidium bin concentration using the 
Cryptosporidium results reported under Sec.  141.702(d) and following 
the procedures in paragraphs (b)(1) through (3) of this section. 
Systems must then determine their bin classification a second time 
using this Cryptosporidium bin concentration and the table in paragraph 
(c) of this section.
    (e) Any filtered system or unfiltered system that is required to 
install filtration that fails to complete the monitoring requirements 
of Sec.  Sec.  141.701 through 141.707 or choses not to monitor 
pursuant to Sec.  141.701(f) must meet the treatment requirements for 
Bin 4 under Sec.  141.720 by the date applicable under Sec.  
141.701(e).

Disinfection Profiling and Benchmarking Requirements


Sec.  141.710  [Reserved].


Sec.  141.711  Determination of systems required to profile.

    (a) Subpart H of this part community and nontransient noncommunity 
water systems serving at least 10,000 people that do not have at least 
5.5 log of Cryptosporidium treatment, equivalent to compliance with Bin 
4 in Sec.  141.720, in place prior to the date when the system is 
required to begin profiling in Sec.  141.712 are required to develop 
Giardia lamblia and virus disinfection profiles.
    (b) Subpart H community and nontransient noncommunity water systems 
serving fewer than 10,000 people that do not have at least 5.5 log of 
Cryptosporidium treatment, equivalent to compliance with Bin 4 in Sec.  
141.720, in place prior to the date when the system is required to 
begin profiling in Sec.  141.712 are required to develop Giardia 
lamblia and virus disinfection profiles if any of the criteria in 
paragraphs (b)(1) through (3) of this section apply.
    (1) TTHM levels in the distribution system are at least 0.064 mg/L 
as a locational running annual average (LRAA) at any monitoring site. 
Systems must base their TTHM LRAA calculation on data collected for 
compliance under subpart L of this part after [Date of Publication of 
Final Rule in the Federal Register], or as determined by the State.

[[Page 47782]]

    (2) HAA5 levels in the distribution system are at least 0.048 mg/L 
as an LRAA at any monitoring site. Systems must base their HAA5 LRAA 
calculation on data collected for compliance under subpart L of this 
part after [Date of Publication of Final Rule in the Federal Register], 
or as determined by the State.
    (3) The system is required to monitor for Cryptosporidium under 
Sec.  141.701(c).
    (c) In lieu of developing a new profile, systems may use the 
profile(s) developed under Sec.  141.172 or Sec.  Sec.  141.530 through 
141.536 if the profile(s) meets the requirements of Sec.  141.713(c).


Sec.  141.712  Schedule for disinfection profiling requirements.

    (a) Systems must comply with the following schedule in the table in 
this paragraph:

                           Schedule of Required Disinfection Profiling Milestones \1\
----------------------------------------------------------------------------------------------------------------
                                                                          Date
                                      --------------------------------------------------------------------------
                                                                   Subpart H systems serving fewer than 10,000
               Activity                   Subpart H systems                          people
                                       serving at least 10,000 -------------------------------------------------
                                                people          Required to monitor for  Not required to monitor
                                                                    Cryptosporidium        for Cryptosporidium
----------------------------------------------------------------------------------------------------------------
1. Report TTHM and HAA5 LRAA results   NA.....................  NA.....................  [Date 42 Months After
 to State.                                                                                Date of Publication of
                                                                                          Final Rule in the
                                                                                          Federal Register].
2. Begin disinfection profiling \1,2\  [Date 24 Months After    [Date 54 Months After    [Date 42 Months After
                                        Date of Publication of   Date of Publication of   Date of Publication of
                                        Final Rule in the        Final Rule in the        Final Rule in the
                                        Federal Register].       Federal Register].       Federal Register] if
                                                                                          required \3\.
3. Complete disinfection profiling     [Date 36 Months After    [Date 66 Months After    [Date 54 Months After
 based on at least one year of data.    Date of Publication of   Date of Publication of   Date of Publication of
                                        Final Rule in the        Final Rule in the        Final Rule in the
                                        Federal Register].       Federal Register].       Federal Register] if
                                                                                          required \3\.
----------------------------------------------------------------------------------------------------------------
\1\ Systems with at least 5.5 log of Cryptosporidium treatment in place are not required to do disinfection
  profiling.
\2\ Systems may use existing operational data and profiles as described in Sec.   141.713(c).
\3\ Systems serving fewer than 10,000 people are not required to conduct disinfection profiling if they are not
  required to monitor for Cryptosporidium and if their TTHM and HAA5 LRAAs do not exceed the levels specified in
  Sec.   141.711(b).

    (b) [Reserved]


Sec.  141.713  Developing a profile.

    (a) Systems required to develop disinfection profiles under Sec.  
141.711 must follow the requirements of this section. Systems must 
monitor at least weekly for a period of 12 consecutive months to 
determeine the total log inactivation for Giardia lamblia and viruses. 
Systems must determine log inactivation for Giardia lamblia through the 
entire plant, based on CT99.9 values in Tables 1.1 through 
1.6, 2.1 and 3.1 of Sec.  141.74(b) as applicable. Systems must 
determine log inactivation for viruses through the entire treatment 
plant based on a protocol approved by the State.
    (b) Systems with a single point of disinfectant application prior 
to the entrance to the distribution system must conduct the monitoring 
in paragraphs (b)(1) through (4) of this section. Systems with more 
than one point of disinfectant application must conduct the monitoring 
in paragraphs (b)(1) through (4) of this section for each disinfection 
segment. Systems must monitor the parameters necessary to determine the 
total inactivation ratio, using analytical methods in Sec.  141.74(a).
    (1) For systems using a disinfectant other than UV, the temperature 
of the disinfected water must be measured at each residual disinfectant 
concentration sampling point during peak hourly flow or at an 
alternative location approved by the State.
    (2) For systems using chlorine, the pH of the disinfected water 
must be measured at each chlorine residual disinfectant concentration 
sampling point during peak hourly flow or at an alternative location 
approved by the State.
    (3) The disinfectant contact time(s) (T) must be determined during 
peak hourly flow.
    (4) The residual disinfectant concentration(s) (C) of the water 
before or at the first customer and prior to each additional point of 
disinfection must be measured during peak hourly flow.
    (c) In lieu of conducting new monitoring under paragraph (b) of 
this section, systems may elect to meet the requirements of paragrphs 
(c)(1) or (2) of this section.
    (1) Systems that have at least 12 consecutive months of existing 
operational data that are substantially equivalent to data collected 
under the provisions of paragraph (b) of this section may use these 
data to develop disinfection profiles as specified in this section if 
the system has neither made a significant change to its treatment 
practice nor changed sources since the data were collected. Systems 
using existing operational data may develop disinfection profiles for a 
period of up to three years.
    (2) Systems may use disinfection profile(s) developed under Sec.  
141.172 or Sec. Sec.  141.530 through 141.536 in lieu of developing a 
new profile if the system has neither made a significant change to its 
treatment practice nor changed sources since the profile was developed. 
Systems that have not developed a virus profile under Sec.  141.172 or 
Sec. Sec.  141.530 through 141.536 must develop a virus profile using 
the same monitoring data on which the Giardia lamblia profile is based.
    (d) Systems must calculate the total inactivation ratio for Giardia 
lamblia as specified in paragraphs (d)(1) through (3) of this section.
    (1) Systems using only one point of disinfectant application may 
determine the total inactivation ratio for the disinfection segment 
based on either of the methods in paragraph (d)(1)(i) or (ii) of this 
section.
    (i) Determine one inactivation ratio (CTcalc/CT99.9) 
before or at the first customer during peak hourly flow.
    (ii) Determine successive CTcalc/CT99.9 values, 
representing sequential inactivation ratios, between the point of 
disinfectant application and a point before or at the first customer 
during peak hourly flow. The system must calculate the total 
inactivation ratio by determining (CTcalc/CT99.9) for each 
sequence and then adding the (CTcalc/CT99.9) values together 
to determine ([Sigma] (CTcalc/CT99.9)).
    (2) Systems using more than one point of disinfectant application 
before the first customer must determine the CT value of each 
disinfection segment immediately prior to the next point of

[[Page 47783]]

disinfectant application, or for the final segment, before or at the 
first customer, during peak hourly flow. The (CTcalc/CT99.9) 
value of each segment and ([Sigma](CTcalc/CT99.9)) must be 
calculated using the method in paragraph (d)(1)(ii) of this section.
    (3) The system must determine the total logs of inactivation by 
multiplying the value calculated in paragraph (d)(1) or (d)(2) of this 
section by 3.0.
    (4) Systems must calculate the log of inactivation for viruses 
using a protocol approved by the State.
    (5) Systems must retain the disinfection profile data in graphic 
form, as a spreadsheet, or in some other format acceptable to the State 
for review as part of sanitary surveys conducted by the State.


Sec.  141.714  Requirements when making a significant change in 
disinfection practice.

    (a) A system that is required to develop a disinfection profile 
under the provisions of this subpart and that plans to make a 
significant change to its disinfection practice must calculate a 
disinfection benchmark and must notify the State prior to making such a 
change. Significant changes to disinfection practice are defined in 
paragraphs (a)(1) through (4) of this section.
    (1) Changes to the point of disinfection;
    (2) Changes to the disinfectant(s) used in the treatment plant;
    (3) Changes to the disinfection process; and
    (4) Any other modification identified by the State.
    (5) Systems must use the procedures specified in paragraphs 
(a)(5)(i) and (ii) of this section to calculate a disinfection 
benchmark.
    (i) For the year of profiling data collected and calculated under 
Sec.  141.713, or for each year with profiles covering more than one 
year, systems must determine the lowest mean monthly level of both 
Giardia lamblia and virus inactivation. Systems must determine the mean 
Giardia lamblia and virus inactivation for each calendar month for each 
year of profiling data by dividing the sum of daily or weekly Giardia 
lamblia and virus log inactivation by the number of values calculated 
for that month.
    (ii) The disinfection benchmark is the lowest monthly mean value 
(for systems with one year of profiling data) or the mean of the lowest 
monthly mean values (for systems with more than one year of profiling 
data) of Giardia lamblia and virus log inactivation in each year of 
profiling data.
    (6) Systems must submit the information in paragraphs (a)(6)(i) 
through (iii) of this section when notifying the State that they are 
planning to make a significant change in disinfection practice.
    (i) A description of the proposed change.
    (ii) The disinfection profile and benchmark for Giardia lamblia and 
viruses determined under Sec. Sec.  141.713 and 141.714.
    (iii) An analysis of how the proposed change will affect the 
current level of disinfection.

Treatment Technique Requirements


Sec.  141.720  Treatment requirements for filtered systems.

    (a) Filtered systems or systems that are unfiltered and required to 
install filtration must provide the level of treatment for 
Cryptosporidium specified in this paragraph, based on their bin 
classification as determined under Sec.  141.709 and their existing 
treatment:

----------------------------------------------------------------------------------------------------------------
                                  And the system uses the following filtration treatment in full compliance with
                                     subpart H, P, and T of this section (as applicable), then the additional
                                                         treatment requirements are . . .
                                 -------------------------------------------------------------------------------
If the system bin classification     Conventional
            is . . .                  filtration                             Slow sand or         Alternative
                                       treatment       Direct filtration  diatomaceous earth      filtration
                                      (including                              filtration         technologies
                                      softening)
----------------------------------------------------------------------------------------------------------------
(1) Bin 1.......................  No additional       No additional       No additional       No additional
                                   treatment.          treatment.          treatment.          treatment
(2) Bin 2.......................  1 log treatment...  1.5 log treatment.  1 log treatment...  (\1\)
(3) Bin 3.......................  2 log treatment...  2.5 log treatment.  2 log treatment...  (\2\)
(4) Bin 4.......................  2.5 log treatment.  3 log treatment...  2.5 log treatment.  (\3\)
----------------------------------------------------------------------------------------------------------------
\1\ As determined by the State such that the total Cryptosporidium removal and inactivation is at least 4.0 log.
 
\2\ As determined by the State such that the total Cryptosporidium removal and inactivation is at least 5.0 log.
 
\3\ As determined by the State such that the total Cryptosporidium removal and inactivation is at least 5.5 log.

    (b) Filtered systems must use one, or a combination, of the 
management and treatment options listed in Sec.  141.722, termed the 
microbial toolbox, to meet the additional Cryptosporidium treatment 
requirements identified for each bin in paragraph (a) of this section.
    (c) Systems classified in Bin 3 and Bin 4 must achieve at least 1 
log of the additional treatment required under paragraph (a) of this 
section using either one or a combination of the following: bag 
filters, bank filtration, cartridge filters, chlorine dioxide, 
membranes, ozone, and/or UV as specified in Sec.  141.722.


Sec.  141.721  Treatment requirements for unfiltered systems.

    (a) Following completion of the initial source water monitoring 
required under Sec.  141.702(a), unfiltered systems that meet all 
filtration avoidance criteria of Sec.  141.71 must calculate the 
arithmetic mean of all Cryptosporidium sample concentrations reported 
under Sec.  141.702(a), along with any previously collected data that 
satisfy the requirements of Sec.  141.708, and must meet the treatment 
requirements in paragraph (b)(1) or (2) of this section, as applicable, 
based on this concentration.
    (b)(1) Unfiltered systems with a mean Cryptosporidium concentration 
of 0.01 oocysts/L or less must provide at least 2 log Cryptosporidium 
inactivation.
    (2) Unfiltered systems with a mean Cryptosporidium concentration of 
greater than 0.01 oocysts/L must provide at least 3 log Cryptosporidium 
inactivation.
    (c) Unfiltered systems must use chlorine dioxide, ozone, or UV as 
specified in Sec.  141.722 to meet the Cryptosporidium inactivation 
requirements of this section.
    (1) Unfiltered systems that use chlorine dioxide or ozone and fail 
to achieve the Cryptosporidium log inactivation required in paragraph 
(b)(1) or (2) of this section, as applicable, on more than one day in 
the calendar month are in violation of the treatment technique 
requirement.
    (2) Unfiltered systems that use UV light and fail to achieve the 
Cryptosporidium log inactivation required in paragraph (b)(1) or (2) of 
this section, as applicable, in at least 95% of the water that is 
delivered to the public during each calendar month, based on monitoring 
required under paragraph Sec.  141.729(d)(4), are in violation of the 
treatment technique requirement.
    (d) Unfiltered systems must meet the combined Cryptosporidium, 
Giardia

[[Page 47784]]

lamblia, and virus inactivation requirements of this section and Sec.  
141.72(a) using a minimum of two disinfectants, and each disinfectant 
must separately achieve the total inactivation required for either 
Cryptosporidium, Giardia lamblia, or viruses.
    (e) Following completion of the second round of source water 
monitoring required under Sec.  141.702(d), unfiltered systems that 
meet all filtration avoidance criteria of Sec.  141.71 must calculate 
the arithmetic mean of all Cryptosporidium sample concentrations 
reported under Sec.  141.702(d) and must meet the treatment 
requirements in paragraph (b)(1) or (2) of this section, as applicable, 
based on this concentration.
    (f) Any unfiltered system that meets all filtration avoidance 
criteria of Sec.  141.71 and fails to complete the monitoring 
requirements of Sec.  Sec.  141.701 through 141.707 or choses not to 
monitor pursuant to Sec.  141.701(g) must meet the treatment 
requirements of paragraph (b)(2) of this section by the date applicable 
under Sec.  141.701(e).


Sec.  141.722  Microbial toolbox options for meeting Cryptosporidium 
treatment requirements.

    (a) To meet the additional Cryptosporidium treatment requirements 
of Sec.  Sec.  141.720 and 141.721, systems must use microbial toolbox 
options listed in this follwing table that are designed, implemented, 
and operated in accordance with the requirements of this subpart.

            Microbial Toolbox: Options, Credits and Criteria
------------------------------------------------------------------------
                                     Proposed Cryptosporidium treatment
          Toolbox option                   credit with design and
                                           implementation criteria
------------------------------------------------------------------------
                        Source Toolbox Components
------------------------------------------------------------------------
(1) Watershed control program.....  0.5 log credit for State approved
                                     program comprising EPA specified
                                     elements. Specific criteria are in
                                     Sec.   141.725(a).
(2) Alternative source/intake       Bin classification based on
 management.                         concurrent Cryptosporidium
                                     monitoring. No presumptive credit.
                                     Specific criteria are in Sec.
                                     141.725(b).
-----------------------------------
                    Pre-Filtration Toolbox Components
------------------------------------------------------------------------
(3) Presedimentation basin with     0.5 log credit for new basins with
 coagulation.                        continuous operation and coagulant
                                     addition. No presumptive credit for
                                     basins existing when monitoring is
                                     required under Sec.   141.702.
                                     Specific criteria are in Sec.
                                     141.726(a).
(4) Two-stage lime softening......  0.5 log credit for two-stage
                                     softening with coagulant addition.
                                     Specific criteria are in Sec.
                                     141.726(b).
(5) Bank filtration...............  0.5 log credit for 25 foot setback;
                                     1.0 log credit for 50 foot setback.
                                     No presumptive credit for bank
                                     filtration existing when monitoring
                                     is required under Sec.
                                     141.704(d)(1). Specific criteria
                                     are in Sec.   141.726(c).
-----------------------------------
                Treatment Performance Toolbox Components
------------------------------------------------------------------------
(6) Combined filter performance...  0.5 log credit for combined filter
                                     effluent turbidity <= 0.15 NTU in
                                     95% of samples each month. Specific
                                     criteria are in Sec.   141.727(a).
(7) Individual filter performance.  1.0 log credit for individual filter
                                     effluent turbidity <=0.1 NTU in 95%
                                     of daily maximum samples each month
                                     and no filter 0.3 NTU in
                                     two consecutive measurements.
                                     Specific criteria are in Sec.
                                     141.727(b).
(8) Demonstration of performance..  Credit based on a demonstration to
                                     the State through State approved
                                     protocol. Specific criteria are in
                                     Sec.   141.727(c).
-----------------------------------
                Additional Filtration Toolbox Components
------------------------------------------------------------------------
(9) Bag filters...................  1 log credit with demonstration of
                                     at least 2 log removal efficiency
                                     in challenge test; Specific
                                     criteria are in Sec.   141.728(a).
(10) Cartridge filters............  2 log credit with demonstration of
                                     at least 3 log removal efficiency
                                     in challenge test; Specific
                                     criteria are in Sec.   141.728(a).
(11) Membrane filtration..........  Log removal credit up to the lower
                                     value of the removal efficiency
                                     demonstrated during the challenge
                                     test or verified by the direct
                                     integrity test applied to the
                                     system. Specific criteria are in
                                     Sec.   141.728(b).
(12) Second stage filtration......  0.5 log credit for a second separate
                                     filtration stage in treatment
                                     process following coagulation.
                                     Specific criteria are in Sec.
                                     141.728(c).
(13) Slow sand filers.............  2.5 log credit for second separate
                                     filtration process. Specific
                                     criteria are in Sec.   141.728(d).
-----------------------------------
                     Inactivation Toolbox Components
------------------------------------------------------------------------
(14) Chlorine dioxide.............  Log credit based on demonstration of
                                     compliance with CT table. Specific
                                     criteria are in Sec.   141.729(b).
(15) Ozone........................  Log credit based on demonstration of
                                     compliance with CT table. Specific
                                     criteria are in Sec.   141.729(c).
(16) UV...........................  Log credit based on demonstration of
                                     compliance with UV dose table.
                                     Specific criteria are in Sec.
                                     141.729(d).
------------------------------------------------------------------------

    (b) Failure to comply with the requirements of this section in 
accordance with the schedule in Sec.  141.701(e) is a treatment 
technique violation.


Sec.  141.723  [Reserved]


Sec.  141.724  Requirements for uncovered finished water storage 
facilities.

    (a) Systems using uncovered finished water storage facilities must 
comply with the conditions of one of the paragraphs (a)(1) through (3) 
of this section for each facility no later than the date specified in 
Sec.  141.701(h).
    (1) Systems must cover any uncovered finished water storage 
facility.
    (2) Systems must treat the discharge from the uncovered finished 
water storage facility to the distribution system to achieve at least 4 
log virus inactivation using a protocol approved by the State.
    (3) Systems must have a State-approved risk mitigation plan for the 
uncovered finished water storage facility that addresses physical 
access and site security, surface water runoff, animal and bird waste, 
and ongoing water quality assessment, and includes a schedule for plan 
implementation. Systems must implement the risk

[[Page 47785]]

mitigation plan approved by the State. Systems must submit risk 
mitigation plans to the State for approval no later than [Date 24 
Months After Date of Publication of Final Rule in the Federal 
Register].
    (b) Failure to comply with the requirements of this section in 
accordance with the schedule in Sec.  141.701(h) is a treatment 
technique violation.

Requirements for Microbial Toolbox Components


Sec.  141.725  Source toolbox components.

    (a) Watershed control program.
    (1) Systems that intend to qualify for a 0.5 log credit for 
Cryptosporidium removal for a watershed control program must notify the 
State no later than one year after completing the source water 
monitoring requirements of Sec.  141.702(b) that they intend to develop 
a watershed control program and to submit it for State approval.
    (2) Systems must submit a proposed initial watershed control plan 
and a request for plan approval and 0.5 log Cryptosporidium removal 
credit to the State no later than two years after completing the source 
water monitoring requirements of Sec.  141.702(b). Based on a review of 
the initial proposed watershed control plan, the State may approve, 
reject, or conditionally approve the plan. If the plan is approved, or 
if the system agrees to implement the State's conditions for approval, 
the system is awarded a 0.5 log credit for Cryptosporidium removal to 
apply against additional treatment requirements.
    (3) The application to the State for initial program approval must 
include elements in paragraphs (a)(3)(i) through (iii) of this section.
    (i) An analysis of the vulnerability of each source to 
Cryptosporidium. The vulnerability analysis must address the watershed 
upstream of the drinking water intake and must include the following: a 
characterization of the watershed hydrology, identification of an 
``area of influence'' (the area to be considered in future watershed 
surveys) outside of which there is no significant probability of 
Cryptosporidium or fecal contamination affecting the drinking water 
intake, identification of both potential and actual sources of 
Cryptosporidium contamination, the relative impact of the sources of 
Cryptosporidium contamination on the system's source water quality, and 
an estimate of the seasonal variability of such contamination.
    (ii) An analysis of control measures that could mitigate the 
sources of Cryptosporidium contamination identified during the 
vulnerability analysis. The analysis of control measures must address 
their relative effectiveness in reducing Cryptosporidium loading to the 
source water and their feasability and sustainability.
    (iii) A plan that establishes goals and defines and prioritizes 
specific actions to reduce source water Cryptosporidium levels. The 
plan must explain how the actions are expected to contribute to 
specific goals, identify watershed partners and their role(s), identify 
resource requirements and commitments, and include a schedule for plan 
implementation.
    (4) Initial State approval of a watershed control plan and its 
associated 0.5 log Cryptosporidium removal credit is valid until the 
system completes the second round of Cryptosporidium monitoring 
required under Sec.  141.702(d). Systems must complete the actions in 
paragraphs (a)(4)(i) through (iv) of this section to maintain State 
approval and the 0.5 log credit.
    (i) Submit an annual watershed control program status report to the 
State by a date determined by the State. The annual watershed control 
program status report must describe the system's implementation of the 
approved plan and assess the adequacy of the plan to meet its goals. It 
must explain how the system is addressing any shortcomings in plan 
implementation, including those previously identified by the State or 
as the result of the watershed survey conducted under paragraph 
(a)(4)(ii) of this section. If it becomes necessary during 
implementation to make substantial changes in its approved watershed 
control program, the system must notify the State and provide a 
rationale prior to making any such changes. If any change is likely to 
reduce the level of source water protection, the system must also 
include the actions it will take to mitigate the effects in its 
notification.
    (ii) Conduct an annual watershed sanitary survey and submit the 
survey report to the State for approval. The survey must be conducted 
according to State guidelines and by persons approved by the State to 
conduct watershed surveys. The survey must encompass the area of the 
watershed that was identified in the State-approved watershed control 
plan as the area of influence and, at a minimum, assess the priority 
activities identified in the plan and identify any significant new 
sources of Cryptosporidium.
    (iii) Submit to the State a request for review and re-approval of 
the watershed control program and for a continuation of the 0.5 log 
removal credit for a subsequent approval period. The request must be 
provided to the State at least six months before the current approval 
period expires or by a date previously determined by the State. The 
request must include a summary of activities and issues identified 
during the previous approval period and a revised plan that addresses 
activities for the next approval period, including any new actual or 
potential sources of Cryptosporidium contamination and details of any 
proposed or expected changes from the existing State-approved program. 
The plan must address goals, prioritize specific actions to reduce 
source water Cryptosporidium, explain how actions are expected to 
contribute to achieving goals, identify partners and their role(s), 
resource requirements and commitments, and the schedule for plan 
implementation.
    (iv) The annual status reports, watershed control plan and annual 
watershed sanitary surveys must be made available to the public upon 
request. These documents must be in a plain language style and include 
criteria by which to evaluate the success of the program in achieving 
plan goals. If approved by the State, the system may withhold portions 
of the annual status report, watershed control plan, and watershed 
sanitary survey based on security considerations.
    (5) Unfiltered systems may not claim credit for Cryptosporidium 
removal under this option.
    (b) Alternative source. (1) If approved by the State, a system may 
be classified in a bin under Sec.  141.709 based on monitoring that is 
conducted concurrently with source water monitoring under Sec.  141.701 
and reflects a different intake location (either in the same source or 
for an alternate source) or a different procedure for managing the 
timing or level of withdrawal from the source.
    (2) Sampling and analysis of Cryptosporidium in the concurrent 
round of monitoring must conform to the requirements for monitoring 
conducted under this subpart to determine bin classification. Systems 
must submit the results of all monitoring to the State, along with 
supporting information documenting the operating conditions under which 
the samples were collected.
    (3) If the State classifies the system in a bin based on monitoring 
that reflects a different intake location or a different procedure for 
managing the timing or level of withdrawal from the source, the system 
must relocate the intake or use

[[Page 47786]]

the intake management strategy, as applicable, no later than the 
applicable date for treatment technique implementation in Sec.  
141.701. The State may specify reporting requirements to verify 
operational practices.


Sec.  141.726  Pre-filtration treatment toolbox components.

    (a) Presedimentation. New presedimentation basins that meet the 
criteria in paragraphs (a)(1) through (4) of this section are eligible 
for 0.5 log Cryptosporidium removal credit. Systems with 
presedimentation basins existing when the system is required to conduct 
monitoring under Sec.  141.702(a) may not claim this credit and, during 
periods when the basins are in use, must collect samples after the 
basins for the purpose of determining bin classification under Sec.  
141.709.
    (1) The presedimentation basin must be in continuous operation and 
must treat all of the flow reaching the treatment plant.
    (2) The system must continuously add a coagulant to the 
presedimentation basin.
    (3) Presedimentation basin influent and effluent turbidity must be 
measured at least once per day or more frequently as determined by the 
State.
    (4) The system must demonstrate on a monthly basis at least 0.5 log 
reduction of influent turbidity through the presedimentation process in 
at least 11 of the 12 previous consecutive months.
    (i) The monthly demonstration of turbidity reduction must be based 
on the mean of daily turbidity readings collected under paragraph 
(a)(3) of this section and calculated as follows: 
log10(monthly mean of daily influent turbidity)--
log10(monthly mean of daily effluent turbidity).
    (ii) If the presedimentation process has not been in operation for 
12 months, the system must verify on a monthly basis at least 0.5 log 
reduction of influent turbidity through the presedimentation process, 
calculated as specified in this paragraph, for at least all but any one 
of the months of operation.
    (b) Two-stage lime softening. Systems that operate a two-stage lime 
softening plant are eligible for an additional 0.5 log Cryptosporidium 
removal credit if there is a second clarification step between the 
primary clarifier and filter(s) that is operated continuously. Both 
clarifiers must treat all of the plant flow and a coagulant, which may 
be excess lime or magnesium hydroxide, must be present in both 
clarifiers.
    (c) Bank filtration. New bank filtration that serves as 
pretreatment to a filtration plant is eligible for either a 0.5 or a 
1.0 log Cryptosporidium removal credit towards the requirements of this 
subpart if it meets the design criteria specified in paragraphs (c)(1) 
through (c)(5) of this section and the monitoring and reporting 
criteria of paragraph (c)(6) of this section. Wells with a ground water 
flow path of at least 25 feet are eligible for 0.5 log removal credit; 
wells with a ground water flow path of at least 50 feet are eligible 
for 1.0 log removal credit. The ground water flow path must be 
determined as specified in paragraph (c)(5) of this section.
    (1) Only horizontal and vertical wells are eligible for bank 
filtration removal credit.
    (2) Only wells in granular aquifers are eligible for bank 
filtration removal credit. Granular aquifers are those comprised of 
sand, clay, silt, rock fragments, pebbles or larger particles, and 
minor cement. The aquifer material must be unconsolidated as 
demonstrated by the aquifer characterization specified in paragraph 
(c)(3) of this section, unless the system meets the conditions of 
paragraph (c)(4) of this section. Wells located in consolidated 
aquifers, fractured bedrock, karst limestone, and gravel aquifers are 
not eligible for bank filtration removal credit.
    (3) A system seeking removal credit for bank filtration must 
characterize the aquifer at the well site to determine aquifer 
properties. The aquifer characterization must include the collection of 
relatively undisturbed continuous core samples from the surface to a 
depth at least equal to the bottom of the well screen. The recovered 
core length must be at least 90 percent of the total projected depth to 
the well screen, and each sampled interval must be a composite of no 
more than 2 feet in length. A well is eligible for removal credit if at 
least 90 percent of the composited intervals from the aquifer contain 
at least 10 percent fine grained material, which is defined as grains 
less than 1.0 mm in diameter.
    (4) Wells constructed in partially consolidated granular aquifers 
are eligible for removal credit if approved by the State based on a 
demonstraton by the system that the aquifer provides sufficient natural 
filtration. The demonstration must include a characterization of the 
extent of cementation and fractures present in the aquifer.
    (5) For vertical wells, the ground water flow path is the measured 
horizontal distance from the edge of the surface water body to the 
well. This horzontal distance to the surface water must be determined 
using the floodway boundary or 100 year flood elevation boundary as 
delineated on Federal Emergency Management Agency (FEMA) Flood 
Insurance Rate maps. If the floodway boundary or 100 year flood 
elevation boundary is not delineated, systems must determine the 
floodway or 100 year flood elevation boundary using methods 
substantially equilvalent to those used in preparing FEMA Flood 
Insurance Rate maps. For horizontal wells, the ground water flow path 
is the closest measured distance from the bed of the river under normal 
flow conditions to the closest horizontal well lateral intake.
    (6) Turbidity measurements must be performed on representative 
samples from each wellhead at least every four hours that the bank 
filtration is in operation. Continuous turbidity monitoring at each 
wellhead may be used if the system validates the continuous measurement 
for accuracy on a regular basis using a protocol approved by the State. 
If the monthly average of daily maximum turbidity values at any well 
exceeds 1 NTU, the system must report this finding to the State within 
30 days. In addition, within 30 days of the exceedance, the system must 
conduct an assessment to determine the cause of the high turbidity 
levels and submit that assessment to the State for a determination of 
whether any previously allowed credit is still appropriate.
    (7) Systems with bank filtration that serves as pretreatment to a 
filtration plant and that exists when the system is required to conduct 
monitoring under Sec.  141.702(a) may not claim this credit. During 
periods when the bank filtration is in use, systems must collect 
samples after the bank filtration for the purpose of determining bin 
classification under Sec.  141.709.


Sec.  141.727  Treatment performance toolbox components.

    (a) Combined filter performance. Systems using conventional 
filtration treatment or direct filtration treatment may claim an 
additional 0.5 log Cryptosporidium removal credit for any month at each 
plant that demonstrates that combined filter effluent (CFE) turbidity 
levels are less than or equal to 0.15 NTU in at least 95 percent of the 
measurements taken each month, based on sample measurements collected 
under Sec.  Sec.  141.73,141.173(a) and 141.551. Systems may not claim 
credit under this paragraph and paragraph (b) in the same month.
    (b) Individual filter performance. Systems using conventional 
filtration treatment or direct filtration treatment

[[Page 47787]]

may claim an additional 1.0 log Cryptosporidium removal credit for any 
month at each plant that meets both the individual filter effluent 
(IFE) turbidity requirements of paragraphs (b)(1) and (2) of this 
section, based on monitoring conducted under Sec.  Sec.  141.174(a) and 
141.560.
    (1) IFE turbidity must be less than 0.1 NTU in at least 95% of the 
maximum daily values recorded at each filter in each month, excluding 
the 15 minute period following return to service from a filter 
backwash.
    (2) No individual filter may have a measured turbidity greater than 
0.3 NTU in two consecutive measurements taken 15 minutes apart.
    (c)(1) Demonstration of performance. Systems may demonstrate to the 
State, through the use of State-approved protocols, that a plant, or 
unit process of a plant, achieves a mean Cryptosporidium removal 
efficiency greater than any presumptive credit specified under Sec.  
141.720 or Sec.  Sec.  141.725 through 141.728. Systems are eligible 
for an increased Cryptosporidium removal credit if the State determines 
that the plant or process can reliably achieve such a removal 
efficiency on a continuing basis and the State provides written 
notification of its determination to the system. States may establish 
ongoing monitoring and/or performance requirements the State determines 
are necessary to demonstrate the greater credit and may require the 
system to report operational data on a monthly basis to verify that 
conditions under which the demonstration of performance was awarded are 
maintained during routine operations. If the State determines that a 
plant, or unit process of a plant, achieves an average Cryptosporidium 
removal efficiency less than any presumptive credit specified under 
Sec.  141.720 or Sec.  Sec.  141.725 through 141.728, the State may 
assign the lower credit to the plant or unit process.
    (2) Systems may not claim presumptive credit for any toolbox box 
component in Sec.  Sec.  141.726, 141.727(a) and (b), or 141.728 if 
that component is also included in the demonstration of performance 
credit.


Sec.  141.728  Additional filtration toolbox components.

    (a) Bag and cartridge filters. Systems are eligible for a 1 log 
Cryptosporidium removal credit for bag filters and a 2 log 
Cryptosporidium removal credit for cartridge filters by meeting the 
criteria in paragraphs (a)(1) through (a)(10) of this section. The 
request to the State for this credit must include the results of 
challenge testing that meets the requirements of paragraphs (a)(2) 
through (a)(9) of this section.
    (1) To receive a 1 log Cryptosporidium removal credit for a bag 
filter, the filter must demonstrate a removal efficiency of 2 log or 
greater for Cryptosporidium. To receive a 2 log Cryptosporidium removal 
credit for a cartridge filter, the filter must demonstrate a removal 
efficiency of 3 log or greater for Cryptosporidium. Removal efficiency 
must be demonstrated through challenge testing conducted according to 
the criteria in paragraphs (a)(2) through (a)(9) of this section. The 
State may accept data from challenge testing conducted prior to [Date 
of Publication of Final Rule in the Federal Register] in lieu of 
additional testing if the prior testing was consistent with the 
criteria specified in paragraphs (a)(2) through (a)(9) of this section.
    (2) Challenge testing must be performed on full-scale bag or 
cartridge filters that are identical in material and construction to 
the filters proposed for use in full-scale treatment facilities for 
removal of Cryptosporidium.
    (3) Challenge testing must be conducted using Cryptosporidium 
oocysts or a surrogate that is removed no more efficiently than 
Cryptosporidium oocysts. The organism or surrogate used during 
challenge testing is referred to as the challenge particulate. The 
concentration of the challenge particulate must be determined using a 
method capable of discreetly quantifying the specific organism or 
surrogate used in the test; gross measurements such as turbidity may 
not be used.
    (4) The maximum feed water concentration that can be used during a 
challenge test must be based on the detection limit of the challenge 
particulate in the filtrate (i.e., filtrate detection limit) and must 
be calculated using the equation in either paragraph (a)(4)(i) or 
(a)(4)(ii) of this section as applicable.
    (i) For cartridge filters: Maximum Feed Concentration = 3.16x10\4\ 
x (Filtrate Detection Limit).
    (ii) For bag filters: Maximum Feed Concentration = 3.16x10\3\ x 
(Filtrate Detection Limit).
    (5) Challenge testing must be conducted at the maximum design flow 
rate for the filter as specified by the manufacturer.
    (6) Each filter evaluated must be tested for a duration sufficient 
to reach 100 percent of the terminal pressure drop, which establishes 
the maximum pressure drop under which the filter may be used to comply 
with the requirements of this subpart.
    (7) Each filter evaluated must be challenged with the challenge 
particulate during three periods over the filtration cycle: within two 
hours of start-up after a new bag or cartridge filter has been 
installed; when the pressure drop is between 45 and 55 percent of the 
terminal pressure drop; and at the end of the run after the pressure 
drop has reached 100 percent of the terminal pressure drop.
    (8) Removal efficiency of a bag or cartridge filter must be 
determined from the results of the challenge test and expressed in 
terms of log removal values using the following equation:

LRV = LOG10(Cf)-LOG10(Cp)


where LRV = log removal value demonstrated during challenge testing; 
Cf = the feed concentration used during the challenge test; 
and Cp = the filtrate concentration observed during the 
challenge test. In applying this equation, the same units must be used 
for the feed and filtrate concentrations. If the challenge particulate 
is not detected in the filtrate, then the term Cp must be 
set equal to the detection limit. An LRV must be calculated for each 
filter evaluated during the testing.
    (9) If fewer than 20 filters are tested, the removal efficiency for 
the filtration device must be set equal to the lowest of the 
representative LRVs among the filters tested. If 20 or more filters are 
tested, then removal efficiency of the filtration device must be set 
equal to the 10th percentile of the representative LRVs among the 
various filters tested. The percentile is defined by (i/(n+1)) where i 
is the rank of n individual data points ordered lowest to highest. If 
necessary, the system may calculate the 10th percentile using linear 
interpolation.
    (10) If a previously tested bag or cartidge filter is modified in a 
manner that could change the removal efficiency of the filter, addition 
challenge testing to demonstrate the removal efficiency of the modified 
filter must be conducted and submitted to the State.
    (b) Membrane filtration. (1) Systems using a membrane filtration 
process, including a membrane cartridge filter that meets the 
definition of membrane filtration and the integrity testing 
requirements of this subpart, are eligible for a Cryptosporidium 
removal credit equal to the lower value of paragraph (b)(1)(i) or 
(b)(1) (ii) of this section:
    (i) The removal efficiency demonstrated during challenge testing 
conducted under the conditions in paragraph (b)(2) of this section.
    (ii) The maximum removal efficiency that can be verified through 
direct integrity testing used with the

[[Page 47788]]

membrane filtration process under the conditions in paragraph (b)(3) of 
this section.
    (2) Challenge Testing. The membrane used by the system must undergo 
challenge testing to evaluate removal efficiency, and the system must 
submit the results of challenge testing to the State. Challenge testing 
must be conducted according to the criteria in paragraphs (b)(2)(i) 
through (b)(2)(vii) of this section. The State may accept data from 
challenge testing conducted prior to [Date of Publication of Final Rule 
in the Federal Register] in lieu of additional testing if the prior 
testing was consistent with the criteria in paragraphs (b)(2)(i) 
through (b)(2) (vii) of this section.
    (i) Challenge testing must be conducted on either a full-scale 
membrane module, identical in material and construction to the membrane 
modules used in the system's treatment facility, or a smaller-scale 
membrane module, identical in material and similar in construction to 
the full-scale module.
    (ii) Challenge testing must be conducted using Cryptosporidium 
oocysts or a surrogate that is removed no more efficiently than 
Cryptosporidium oocysts. The organism or surrogate used during 
challenge testing is referred to as the challenge particulate. The 
concentration of the challenge particulate must be determined using a 
method capable of discretely quantifying the specific challenge 
particulate used in the test; gross measurements such as turbidity may 
not be used.
    (iii) The maximum feed water concentration that can be used during 
a challenge test is based on the detection limit of the challenge 
particulate in the filtrate and must be determined according to the 
following equation:

Maximum Feed Concentration = 3.16x10\6\ x (Filtrate Detection Limit)

    (iv) Challenge testing must be conducted under representative 
hydraulic conditions at the maximum design flux and maximum design 
process recovery specified by the manufacture for the membrane module. 
Flux is defined as the rate of flow per unit of membrane area. Recovery 
is defined as the ratio of filtrate volume produced by a membrane to 
feed water volume applied to a membrane over the course of an 
uninterrupted operating cycle. An operating cycle is bounded by two 
consecutive backwash or cleaning events. For the purpose of challenge 
testing in this section, recovery does not consider losses that occur 
due to the use of filtrate in backwashing or cleaning operations.
    (v) Removal efficiency of a membrane module during challenge 
testing must be determined as a log removal using the following 
equation:

LRV = LOG10(Cf) - LOG10(Cp)


where LRV = log removal value demonstrated during challenge testing; 
Cf = the feed concentration used during the challenge test; 
and Cp = the filtrate concentration observed during the 
challenge test. Equivalent units must be used for the feed and filtrate 
concentrations. If the challenge particulate is not detected in the 
filtrate, the term Cp is set equal to the detection limit. 
An LRV must be calculated for each membrane module evaluated during the 
test.
    (vi) The removal efficiency of a membrane filtration process 
demonstrated during challenge testing must be expressed as a log 
removal value (LRVC-Test). If fewer than 20 modules are 
tested, then LRVC-Test is equal to the lowest of the 
representative LRVs among the applicable modules tested. If 20 or more 
modules are tested, then LRVC-Test is equal to the 10th 
percentile of the representative LRVs among the applicable modules 
tested. The percentile is defined by (i/(n+1)) where i is the rank of n 
individual data points ordered lowest to highest. If necessary, the 
10th percentile may be calculated using linear interpolation.
    (vii) The challenge test must establish a quality control release 
value (QCRV) for a non-destructive performance test that demonstrates 
the Cryptosporidium removal capability of the membrane filtration 
process. This performance test must be applied to each production 
membrane module used by the system that did not undergo a challenge 
test in order to verify Cryptosporidium removal capability. Production 
modules that do not meet the established QCRV are not eligible for the 
removal credit demonstrated during the challenge test.
    (viii) If a previously tested membrane is modified in a manner that 
could change the removal efficiency of the membrane or the 
applicability of the non-destructive performance test and associated 
QCRV, addition challenge testing to demonstrate the removal efficiency 
of, and determine a new QCRV for, the modified membrane must be 
conducted and submitted to the State.
    (3) Direct integrity testing. Systems must conduct direct integrity 
testing in a manner that demonstrates a removal efficiency equal to or 
greater than the removal credit awarded to the membrane filtration 
process and meets the requirements described in paragraphs (b)(3)(i) 
through (b)(3)(vi) of this section.
    (i) The direct integrity test must be independently applied to each 
membrane unit in service. A membrane unit is a group of membrane 
modules that share common valving that allows the unit to be isolated 
from the rest of the system for the purpose of integrity testing or 
maintenance.
    (ii) The direct integrity method must have a resolution of 3 [mu]m 
or less, where resolution is defined as the smallest leak size that 
contributes to a response from the direct integrity test.
    (iii) The system must demonstrate that the direct integrity test 
can verify the log removal credit awarded to the membrane filtration 
process by the State using the approach in either paragraph 
(b)(2)(iii)(A) or (b)(2)(iii)(B) of this section as applicable based on 
the type of direct integrity test.
    (A) For direct integrity tests that use an applied pressure or 
vacuum, the maximum log removal value that can be verified by the test 
must be calculated according to the following equation:

LRVDIT = LOG10(Qp /(VCF x 
Qbreach))


where LRVDIT = maximum log removal value that can be 
verified by a direct integrity test; Qp = total design 
filtrate flow from the membrane unit; Qbreach = flow of 
water from an integrity breach associated with the smallest integrity 
test response that can be reliably measured, and VCF = volumetric 
concentration factor. The volumetric concentration factor is the ratio 
of the suspended solids concentration on the high pressure side of the 
membrane relative to that in the feed water.
    (B) For direct integrity tests that use a particulate or molecular 
marker, the maximum log removal value that can be verified by the test 
must be calculated according to the following equation:

    LRVDIT = LOG10(Cf)-
LOG10(Cp)


where LRVDIT = maximum log removal value that can be 
verified by a direct integrity test; Cf = the typical feed 
concentration of the marker used in the test; and Cp = the 
filtrate concentration of the marker from an integral membrane unit.
    (iv) Systems must establish a control limit for the direct 
integrity test that is indicative of an integral membrane unit capable 
of meeting the removal credit awarded by the State.
    (v) If the result of a direct integrity test is outside the control 
limit established under paragraphs (b)(3)(i) through (b)(3)(iv) of this 
section, the membrane unit must be removed from service. A direct 
integrity test must be

[[Page 47789]]

conducted to verify any repairs, and the membrane unit may be returned 
to service only if the direct integrity test is within the established 
control limit.
    (vi) Direct integrity testing must be conducted on each membrane 
unit at a frequency of not less than once each day that the membrane 
unit is in operation.
    (4) Indirect integrity monitoring. Systems must conduct continuous 
indirect integrity monitoring on each membrane unit according to the 
criteria in paragraphs (b)(4)(i) through (b)(4)(v) of this section. A 
system that implements continuous direct integrity testing of membrane 
units in accordance with the criteria in paragraphs (b)(3)(i) through 
(b)(3)(v) of this section is not subject to the requirements for 
continuous indirect integrity monitoring.
    (i) Unless the State approves an alternative parameter, continuous 
indirect integrity monitoring must include continuous filtrate 
turbidity monitoring.
    (ii) Continuous monitoring must be conducted at a frequency of no 
less than once every 15 minutes.
    (iii) Continuous monitoring must be separately conducted on each 
membrane unit.
    (iv) If indirect integrity monitoring includes turbidity and if the 
filtrate turbidity readings are above 0.15 NTU for a period greater 
than 15 minutes (i.e., two consecutive 15-minute readings above 0.15 
NTU), direct integrity testing must be performed on the associated 
membrane units as specified in paragraphs (b)(3)(i) through (b)(3)(v) 
of this section.
    (v) If indirect integrity monitoring includes a State-approved 
alternative parameter and if the alternative parameter exceeds a State-
approved control limit for a period greater than 15 minutes, direct 
integrity testing must be performed on the associated membrane units as 
specified in paragraphs (b)(3)(i) through (b)(3)(v) of this section.
    (c) Second stage filtration. Systems are eligible for an additional 
0.5 log Cryptosporidium removal credit if they have a separate second 
stage filtration process consisting of rapid sand, dual media, GAC, or 
other fine grain media in a separate stage following rapid sand or dual 
media filtration. To be eligible for this credit, the first stage of 
filtration must be preceded by a coagulation step and both filtration 
stages must treat 100% of the flow. A cap, such as GAC, on a single 
stage of filtration is not eligible for this credit.
    (d) Slow sand filtration. Systems may claim a 2.5 log 
Cryptosporidium removal credit for a slow sand filtration process that 
follows another separate filtration process if all the flow is treated 
by both processes and no disinfectant residual is present in the 
influent water to the slow sand filtration process.


Sec.  141.729  Inactivation toolbox components.

    (a) Calculation of CT values. (1) CT is the product of the 
disinfectant contact time (T, in minutes) and disinfectant 
concentration (C, in milligrams per liter). Systems must calculate CT 
at least once each day, with both C and T measured during peak hourly 
flow as specified in Sec. Sec.  141.74(a) and 141.74(b).
    (2) Systems with several disinfection segments (a segment is 
defined as a treatment unit process with a measurable disinfectant 
residual level and a liquid volume) in sequence along the treatment 
train, may calculate the CT for each disinfection segment and use the 
sum of the Cryptosporidium log inactivation values achieved through the 
plant.
    (b) CT values for chlorine dioxide. (1) Systems using chlorine 
dioxide must calculate CT in accordance with Sec.  141.729(a).
    (2) Unless the State approves alternative CT values for a system 
under paragraph (b)(3) of this section, systems must use the following 
table to determine Cryptosporidium log inactivation credit:

                                             CT Values for Cryptosporidium Inactivation by Chlorine Dioxide
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   Water Temperature, [deg] C \1\
                Log credit                 -------------------------------------------------------------------------------------------------------------
                                              <=0.5        1          2          3          5          7          10         15         20         25
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.5.......................................        319        305        279        256        214        180        138         89         58         38
1.0.......................................        637        610        558        511        429        360        277        179        116         75
1.5.......................................        956        915        838        767        643        539        415        268        174        113
2.0.......................................       1275       1220       1117       1023        858        719        553        357        232        150
2.5.......................................       1594       1525       1396       1278       1072        899        691        447        289        188
3.0.......................................       1912       1830       1675       1534       1286       1079        830        536        347       226
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ CT values between the indicated temperatures may be determined by interpolation.

    (3) Systems may conduct a site-specific inactivation study to 
determine the CT values necessary to meet a specified Cryptosporidium 
log inactivation level, using a State-approved protocol. The 
alternative CT values determined from the site-specific study and the 
method of calculation must be approved by the State.
    (c) CT values for ozone. (1) Systems using ozone must calculate CT 
in accordance with Sec.  141.729(a).
    (2) Unless the State approves alternative CT values for a system 
under paragraph (c)(3) of this section, systems must use the following 
table to determine Cryptosporidium log inactivation credit:

                                                   CT Values for Cryptosporidium Inactivation by Ozone
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Water Temperature, [deg]C1 \1\
             Log credit              -------------------------------------------------------------------------------------------------------------------
                                        <=0.5        1          2           3           5           7          10          15          20          25
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.5.................................         12         12         10         9.5         7.9         6.5         4.9         3.1         2.0        1.2
1.0.................................         24         23         21        19          16          13           9.9         6.2         3.9        2.5
1.5.................................         36         35         31        29          24          20          15           9.3         5.9        3.7
2.0.................................         48         46         42        38          32          26          20          12           7.8        4.9
2.5.................................         60         58         52        48          40          33          25          16           9.8        6.2

[[Page 47790]]

 
3.0.................................         72         69         63        57          47          39          30          19          12         7.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ CT values between the indicated temperatures may be determined by interpolation

    (3) Systems may conduct a site-specific inactivation study to 
determine the CT values necessary to meet a specified Cryptosporidium 
log inactivation level, using a State-approved protocol. The 
alternative CT values determined from the site-specific study and the 
method of calculation must be approved by the State.
    (d) Ultraviolet light. (1) Systems may claim credit for ultraviolet 
(UV) processes for inactivation of Cryptosporidium, Giardia lamblia, 
and viruses. The allowable inactivation credit for each pathogen must 
be based on the UV dose delivered by the system's UV reactors in 
relation to the UV dose table in paragraph (d)(2) of this section.
    (2) UV dose table. The log credits given in this UV dose table are 
for UV light at a wavelength of 254 nm as produced by a low pressure 
mercury vapor lamp. Systems may apply this table to UV reactors with 
other lamp types through reactor validation testing (i.e., performance 
demonstration) as described in paragraph (d)(3) of this section. The UV 
dose values in this table are applicable only to post-filter 
application of UV in systems that filter under subpart H of this part 
and to unfiltered systems meeting the filtration avoidance criteria in 
subparts H, P, and T of this part:

                UV Dose Table for Cryptosporidium, Giardia Lamblia, and Virus Inactivation Credit
----------------------------------------------------------------------------------------------------------------
                                                                Cryptosporidium  Giardia lamblia
                          Log credit                             UV Dose (mJ/cm   UV dose (mJ/cm   Virus UV dose
                                                                      \2\)             \2\)         (mJ/cm \2\)
----------------------------------------------------------------------------------------------------------------
0.5...........................................................              1.6              1.5              39
1.0...........................................................              2.5              2.1              58
1.5...........................................................              3.9              3.0              79
2.0...........................................................              5.8              5.2             100
2.5...........................................................              8.5              7.7             121
3.0...........................................................             12               11               143
3.5...........................................................             NA               NA               163
4.0...........................................................             NA               NA               186
----------------------------------------------------------------------------------------------------------------

    (3) Reactor validation testing. For a system to receive 
inactivation credit for a UV reactor, the reactor must undergo the 
validation testing in paragraphs (d)(3)(i) and (d)(3)(ii) of this 
section, unless the State approves an alternative approach. The 
validation testing must demonstrate the operating conditions under 
which the reactor can deliver the UV dose required in paragraph (d)(2) 
of this section.
    (i) Validation testing of UV reactors must determine a range of 
operating conditions that can be monitored by the system and under 
which the reactor delivers the required UV dose. At a minimum, these 
operating conditions must include flow rate, UV intensity as measured 
by a UV sensor, and UV lamp status. The validated operating conditions 
determined by this testing must account for the following: UV 
absorbance of the water; lamp fouling and aging; measurement 
uncertainty of on-line sensors; UV dose distributions arising from the 
velocity profiles through the reactor; failure of UV lamps or other 
critical system components; and inlet and outlet piping or channel 
configurations of the UV reactor.
    (ii) Validation testing must include the following: full scale 
testing of a reactor that conforms uniformly to the UV reactors used by 
the system; and inactivation of a test microorganism whose dose 
response characteristics have been quantified with a low pressure 
mercury vapor lamp.
    (4) Reactor monitoring. Systems must monitor their UV reactors to 
demonstrate that they are operating within the range of conditions that 
were validated by the testing described in paragraphs (d)(3)(i) and 
(d)(3)(ii) of this section to achieve the required UV dose in paragraph 
(d)(2) of this section. Systems must monitor for UV intensity as 
measured by a UV sensor, flow rate, and lamp outage and for any other 
parameters required by the State. Systems must verify the calibration 
of UV sensors and must recalibrate sensors in accordance with a 
protocol approved by the State.

Reporting and Recordkeeping Requirements


Sec.  141.730  Reporting requirements.

    (a) Systems must follow the requirements for reporting sampling 
schedules under Sec.  141.703 and for reporting source water monitoring 
results under Sec.  141.707 unless they notify the State that they will 
not conduct source water monitoring due to meeting the criteria of 
Sec.  141.701(f) or (g).
    (b) Systems using uncovered finished water storage facilities must 
notify the State of the use of each facility no later than [Date 24 
Months After Date of Publication of Final Rule in the Federal 
Register].
    (c) Filtered systems and unfiltered systems that are required to 
install filtration must report their Cryptosporidium bin 
classification, as determined under using the procedures in Sec.  
141.709, to the State by the applicable dates in paragraph (c)(1) or 
(2) of this section.
    (1) Systems that serve at least 10,000 people must report their 
initial bin classification no later than [Date 36 Months After Date of 
Publication of Final Rule in the Federal Register] and must report 
their bin classification determined using results from the second round 
of source water monitoring no later than [Date 138 Months After Date of 
Publication of Final Rule in the Federal Register].

[[Page 47791]]

    (2) Systems that serve fewer than 10,000 people must report their 
initial bin classification no later than [Date 66 Months After Date of 
Publication of Final Rule in the Federal Register] and must report 
their bin classification determined using results from the second round 
of source water monitoring no later than [Date 174 Months After Date of 
Publication of Final Rule in the Federal Register].
    (d) Unfiltered systems that meet all filtration avoidance criteria 
of Sec.  141.71 must report their mean Cryptosporidium concentration, 
as determined under Sec.  141.721, to the State by the applicable dates 
in paragraph (d)(1) or (2) of this section.
    (1) Systems that serve at least 10,000 people must report their 
initial mean Cryptosporidium concentration no later than [Date 36 
Months After Date of Publication of Final Rule in the Federal Register] 
and must report their mean Cryptosporidium concentration determined 
using results from the second round of source water monitoring no later 
than [Date 138 Months After Date of Publication of Final Rule in the 
Federal Register].
    (2) Systems that serve fewer than 10,000 people must report their 
initial mean Cryptosporidium concentration no later than [Date 66 
Months After Date of Publication of Final Rule in the Federal Register] 
and must report their mean Cryptosporidium concentration determined 
using results from the second round of source water monitoring no later 
than [Date 174 Months After Date of Publication of Final Rule in the 
Federal Register].
    (e) Systems must report to the State in accordance with the 
following table in this paragraph for any toolbox options used to 
comply with the Cryptosporidium treatment technique requirements under 
Sec.  141.720 or Sec.  141.721. The State may place additional 
reporting requirements it determines to be necessary to verify 
operation in accordance with required criteria for all toolbox options:

                                    Microbial Toolbox Reporting Requirements
----------------------------------------------------------------------------------------------------------------
                                                                On the following
                                       Systems must submit    schedule\1\ --systems        On the following
           Toolbox option                 the following       serving =       schedule\1\--systems
                                           information            10,000 people        serving < 10,000 people
----------------------------------------------------------------------------------------------------------------
(1) Watershed control program (WCP)  (i) Notify State of     No later than [Date 48  No later than [Date 78
                                      intention to develop    Months After Date of    Months After Date of
                                      WCP.                    Publication of Final    Publication of Final Rule
                                                              Rule in the Federal     in the Federal Register].
                                                              Register].
                                     (ii) Submit initial     No later than [Date 60  No later than [Date 90
                                      WCP plan to State.      Months After Date of    Months After Date of
                                                              Publication of Final    Publication of Final Rule
                                                              Rule in the Federal     in the Federal Register].
                                                              Register].
                                     (iii) Annual report     By a date determined    By a date determined by the
                                      and State-approved      by the State, every     State, every 12 months,
                                      watershed survey        12 months, beginning    beginning on [Date 114
                                      report.                 on [Date 84 Months      Months After Date of
                                                              After Date of           Publication of Final Rule
                                                              Publication of Final    in the Federal Register].
                                                              Rule in the Federal
                                                              Register].
                                     (iv) Request for re-    Six months prior to     Six months prior to the end
                                      approval and report     the end of the          of the current approval
                                      on the previous         current approval        period or by a date
                                      approval period.        period or by a date     previously determined by
                                                              previously determined   the State.
                                                              by the State.
(2) Bank filtration................  (i) Initial             Initial demonstration   Initial demonstration no
                                      demonstration of the    no later than [Date     later than [Date 102
                                      following:              72 Months after Date    Months after Date of
                                      unconsolidated,         of Publication of       Publication of Final Rule
                                      predominantly sandy     Final Rule in the       in the Federal Register].
                                      aquifer and setback     Federal Register].
                                      distance of at least
                                      25 ft. (0.5 log
                                      credit) or 50 ft.
                                      (1.0 log credit).
                                     (ii) If monthly         Report within 30 days   Report within 30 days
                                      average of daily max    following the month     following the month in
                                      turbidity is greater    in which the            which the monitoring was
                                      than 1 NTU then         monitoring was          conducted, beginning on
                                      system must report      conducted, beginning    [Date 102 Months After
                                      result and submit an    on [Date 72 Months      Date of Publication of
                                      assessment of the       After Date of           Final Rule in the Federal
                                      cause.                  Publication of Final    Register].
                                                              Rule in the Federal
                                                              Register].
(3) Presedimentation...............  Monthly verification    Monthly reporting       Monthly reporting within 10
                                      of the following;       within 10 days          days following the month
                                      Continuous basin        following the month     in which the monitoring
                                      operation; treatment    in which the            was conducted, beginning
                                      of 100% of the flow;    monitoring was          on [Date 102 Months After
                                      continuous addition     conducted, beginning    Date of Publication of
                                      of a coagulant; and     on [Date 72 Months      Final Rule in the Federal
                                      at least 0.5 log        After Date of           Register].
                                      removal of influent     Publication of Final
                                      turbidity based on      Rule in the Federal
                                      the monthly mean of     Register].
                                      daily turbidity
                                      readings for 11 of
                                      the 12 previous
                                      months.
(4) Two-sage lime softening........  Monthly verification    Monthly reporting       Monthly reporting within 10
                                      of the following:       within 10 days          days following the month
                                      Continuous operation    following the month     in which the monitoring
                                      of a second             in which the            was conducted, beginning
                                      clarification step      monitoring was          on [Date 102 Months After
                                      between the primary     conducted, beginning    Date of Publication of
                                      clarifier and filter;   on [Date 72 Months      Final Rule in the Federal
                                      continuous presence     After Date of           Register].
                                      of a coagulant in       Publication of Final
                                      both primary and        Rule in the Federal
                                      secondary clarifiers;   Register].
                                      and both clarifiers
                                      treated 100% of the
                                      plant flow.

[[Page 47792]]

 
(5) Combined filter performance....  Monthly verification    Monthly reporting       Monthly reporting within 10
                                      of combined filter      within 10 days          days following the month
                                      effluent (CFE)          following the month     in which the monitoring
                                      turbidity levels less   in which the            was conducted, beginning
                                      than or equal to 0.15   monitoring was          on [Date 102 Months After
                                      NTU in at least 95      conducted, beginning    Date of Publication of
                                      percent of the 4 hour   on [Date 72 Months      Final Rule in the Federal
                                      CFE measurements        After Date of           Register].
                                      taken each month.       Publication of Final
                                                              Rule in the Federal
                                                              Register].
(6) Individual filter performance..  Monthly verification    Monthly reporting       Monthly reporting within 10
                                      of the following:       within 10 days          days following the month
                                      Individual filter       following the month     in which the monitoring
                                      effluent (IFE)          in which the            was conducted, beginning
                                      turbidity levels less   monitoring was          on [Date 102 Months After
                                      than or equal to 0.1    conducted, beginning    Date of Publication of
                                      NTU in at least 95      on [Date 72 Months      Final Rule in the Federal
                                      percent of all daily    After Date of           Register].
                                      maximum IFE             Publication of Final
                                      measurements taken      Rule in the Federal
                                      each month (excluding   Register].
                                      15 min period
                                      following start-up
                                      after backwash); and
                                      no individual filter
                                      greater than 0.3 NTU
                                      in two consecutive
                                      readings 15 minutes
                                      apart.
(7) Membrane filtration............  (i) Results of          No later than [Date 72  No later than [Date 102
                                      verification testing    Months After Date of    Months After Date of
                                      demonstrating the       Publication of Final    Publication of Final Rule
                                      following: Removal      Rule in the Federal     in the Federal Register].
                                      efficiency              Register].
                                      established through
                                      challenge testing
                                      that meets criteria
                                      in this subpart; and
                                      integrity testing and
                                      associated baseline.
                                     (ii) Monthly report     Within 10 days          Within 10 days following
                                      summarizing all         following the month     the month in which
                                      direct integrity        in which monitoring     monitoring was conducted,
                                      tests above the         was conducted,          beginning [Date 102 Months
                                      control limit and, if   beginning [Date 72      After Date of Publication
                                      applicable, any         Months After Date of    of Final Rule in the
                                      indirect integrity      Publication of Final    Federal Register].
                                      monitoring results      Rule in the Federal
                                      triggering direct       Register].
                                      integrity testing and
                                      the corrective action
                                      that was taken.
(8) Bag filters and cartridge        (i) Demonstration that  No later than [Date 72  No later than [Date 102
 filters.                             the following           Months After Date of    Months After Date of
                                      criteria are met:       Publication of Final    Publication of Final Rule
                                      process meets the       Rule in the Federal     in the Federal Register].
                                      definition of bag or    Register].
                                      cartridge filtration;
                                      removal efficiency
                                      established through
                                      challenge testing
                                      that meets criteria
                                      in this subpart; and
                                      challenge test shows
                                      at least 2 log
                                      removal for bag
                                      filters and 3 log
                                      removal for cartridge
                                      filters.
                                     (ii) Monthly            Within 10 days          Within 10 days following
                                      verification that       following the month     the month in which
                                      100% of flow was        in which monitoring     monitoring was conducted,
                                      filtered.               was conducted,          beginning [Date 102 Months
                                                              beginning [Date 72      After Date of Publication
                                                              Months After Date of    of Final Rule in the
                                                              Publication of Final    Federal Register].
                                                              Rule in the Federal
                                                              Register].
(9) Second stage filtration........  Monthly verification    Within 10 days          Within 10 days following
                                      that 100% of flow was   following the month     the month in which
                                      filtered through both   in which monitoring     monitoring was conducted,
                                      stages.                 was conducted,          beginning [Date 102 Months
                                                              beginning [Date 72      After Date of Publication
                                                              Months After Date of    of Final Rule in the
                                                              Publication of Final    Federal Register].
                                                              Rule in the Federal
                                                              Register].
(10) Slow and filtration...........  Monthly verification    Within 10 days          Within 10 days following
                                      that 100% of flow was   following the month     the month in which
                                      filtered.               in which monitoring     monitoring was conducted,
                                                              was conducted,          beginning [Date 102 Months
                                                              beginning [Date 72      After Date of Publication
                                                              Months After Date of    of Final Rule in the
                                                              Publication of Final    Federal Register].
                                                              Rule in the Federal
                                                              Register].
(11) Chlorine dioxide..............  Summary of CT values    Within 10 days          Within 10 days following
                                      for each day based on   following the month     the month in which
                                      Table in Sec.           in which monitoring     monitoring was conducted,
                                      141.729(b).             was conducted,          beginning [Date 102 Months
                                                              beginning [Date 72      After Date of Publication
                                                              Months After Date of    of Final Rule in the
                                                              Publication of Final    Federal Register].
                                                              Rule in the Federal
                                                              Register].

[[Page 47793]]

 
(12) Ozone.........................  Summary of CT values    Within 10 days          Within 10 days following
                                      for each day based on   following the month     the month in which
                                      Table in Sec.           in which monitoring     monitoring was conducted,
                                      141.729(c).             was conducted,          beginning [Date 102 Months
                                                              beginning [Date 72      After Date of Publication
                                                              Months After Date of    of Final Rule in the
                                                              Publication of Final    Federal Register].
                                                              Rule in the Federal
                                                              Register].
(13) UV............................  (i) Validation test     No later than [Date 72  No later than [Date 102
                                      results demonstrating   Months After Date of    Months After Date of
                                      operating conditions    Publication of Final    Publication of Final Rule
                                      that achieve required   Rule in the Federal     in the Federal Register].
                                      UV dose.                Register].
                                     (ii) Monthly report     Within 10 days          Within 10 days following
                                      summarizing the         following the month     the month in which
                                      percentage of water     in which monitoring     monitoring was conducted,
                                      entering the            was conducted,          beginning [Date 102 Months
                                      distribution system     beginning [Date 72      After Date of Publication
                                      that was not treated    Months After Date of    of Final Rule in the
                                      by UV reactors          Publication of Final    Federal Register].
                                      operating within        Rule in the Federal
                                      validated conditions    Register].
                                      for the required dose
                                      as specified in Sec.
                                       141.729(d).
(14) Demonstration of performance..  (i) Results from        No later than [Date 72  No later than [Date 102
                                      testing following a     Months After Date of    Months After Date of
                                      State approved          Publication of Final    Publication of Final Rule
                                      protocol.               Rule in the Federal     in the Federal Register].
                                                              Register].
                                     (ii) As required by     Within 10 days          Within 10 days following
                                      the State, monthly      following the month     the month in which
                                      verification of         in which monitoring     monitoring was conducted,
                                      operation within        was conducted,          beginning [Date 102 Months
                                      conditions of State     beginning [Date 72      After Date of Publication
                                      approval for            Months After Date of    of Final Rule in the
                                      demonstration of        Publication of Final    Federal Register].
                                      performance credit.     Rule in the Federal
                                                              Register].
----------------------------------------------------------------------------------------------------------------
\1\ States may allow up to an additional two years to the date when the first submittal must be completed for
  systems making capital improvements.

    (f) Systems must report to the State the information associated 
with disinfection profiling and benchmarking requirements of Sec. Sec.  
141.711 to 141.714 in accordance with the tables in this paragraph.

                    Table 1.--Disinfection Profiling Reporting Requirements for Large Systems
                                       [Serving =10,000 people]
----------------------------------------------------------------------------------------------------------------
                                                                  Submit the following       On the following
             System type                 Benchmark component             items                   schedule
----------------------------------------------------------------------------------------------------------------
(1) Systems required to conduct        (i) Characterization of  Giardia lamblia and      No later than [Date 36
 Cyrptosporidium monitoring.            disinfection             virus inactivation       Months After Date of
                                        practices. See Sec.      profiles must be on      Publication of Final
                                        141.713.                 file for State review    Rule in the Federal
                                                                 during sanitary survey.  Register].
                                       (ii) State review of     Inactivation profile     Prior to significant
                                        proposed significant     and benchmark            modification of
                                        changes to               determinations.          disinfection practice.
                                        disinfection practice.
                                        See Sec.   141.714.
(2) Systems not required to conduct    (i) Applicability......  None...................  None.
 Cryptosporidium monitoring \a\.
                                       (ii) Characterization    None...................  None.
                                        of Disinfection
                                        Practices.
                                       (iii) State Review of    None...................  None.
                                        Proposed Changes to
                                        Disinfection Practices.
----------------------------------------------------------------------------------------------------------------
\a\Systems that provide at least 5.5 log of Cryptosporidium treatment, consistent with a Bin 4 treatment
  requirement, are not required to conduct Cryptosporidium monitoring.


                    Table 2.--Disinfection Profiling Reporting Requirements for Small Systems
                                            [Serving < 10,000 people]
----------------------------------------------------------------------------------------------------------------
                                                                  Submit the following       On the following
             System type                 Benchmark component             items                   schedule
----------------------------------------------------------------------------------------------------------------
(1) Systems required to conduct        (i) Characterization of  Giardia lamblia and      No later than [Date 66
 Cryptosporidium monitoring.            disinfection             virus disinfection       Months After Date of
                                        practices. See Sec.      profiles must be on      Publication of Final
                                        141.713.                 file for State review    Rule in the Federal
                                                                 during sanitary survey.  Register].

[[Page 47794]]

 
                                       (ii) State review of     Disinfection profiles    Prior to significant
                                        proposed significant     and benchmark            modification of
                                        changes to               determinations.          disinfection practice.
                                        disinfection
                                        practices. See Sec.
                                        141.714.
(2) Systems not required to conduct    (i) Determination of     Report on TTHM and HAA5  No later than [Date 42
 Cryptosporidium monitoring and that    requirement to           LRAA values from         Months After Date of
 exceed DBP triggers a,b,c.             profile. See Sec.        monitoring under         Publication of Final
                                        141.711(b).              subpart L.               Rule in the Federal
                                                                                          Register].
                                       (ii) Characterization    Giardia lambia and       No later than [Date 54
                                        of disinfection          virus disinfection       Months after Date of
                                        practices. See Sec.      profiles must be on      Publication of Final
                                        141.713.                 file for State review    Rule in the Federal
                                                                 during sanitary survey.  Register].
                                       (iii) State review of    Disinfection profiles    Prior to significant
                                        proposed significant     and benchmark            modification of
                                        changes to               determinations.          disinfection practice.
                                        disinfection
                                        practices. See Sec.
                                        141.714.
(3) Systems not required to conduct    (i) Determination of no  Report on TTHM and HAA5  No later than [Date 42
 Cryptosporidium monitoring and that    requirement to           LRAA values from         Months After Date of
 do not exceed DBP triggers \b,c\.      profile. See Sec.        monitoring under         Publication of Final
                                        141.711(b).              subpart L.               Rule in the Federal
                                                                                          Register].
                                       (ii) Characterization    None...................  None.
                                        of disinfection
                                        practices. See Sec.
                                        141.713.
                                       (iii) State review of    None...................  None.
                                        proposed significant
                                        changes to
                                        disinfection practice.
                                        See Sec.   141.714.
----------------------------------------------------------------------------------------------------------------
\a\ Systems that provide at least 5.5 log of Cryptosporidium treatment, consistent with a Bin 4 treatment
  requirement, are not required to conduct Cryptosporidium monitoring.
\b\ See Sec.   141.702(b) to determine if Cryptosporidium monitoring is required.
\c\ See Sec.   141.711(b) to determine if disinfection profiling is required based on TTHM or HAA5 LRAA.

Sec.  141.731  Recordkeeping requirements.

    (a) Systems must keep results from monitoring required under Sec.  
141.702 until 36 months after all source water monitoring required 
under this section has been completed.
    (b) Systems must keep a record of any notification to the State 
that they will not conduct source water monitoring due to meeting the 
criteria of Sec.  141.701(f) or (g).
    (c) Systems required to develop disinfection profiles under Sec.  
141.711 must keep disinfection profiles on file for State review during 
sanitary surveys.

PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS 
IMPLEMENTATION

    5. The authority citation for part 142 continues to read as 
follows:

    Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9 and 300j-11.

    6. Section 142.14 is amended by adding paragraphs (a)(8) and (a)(9) 
to read as follows:


Sec.  142.14  Records kept by States.

* * * * *
    (a) * * *
    (8) [Reserved]
    (9) Any decisions made pursuant to the provisions of part 141, 
subpart W of this chapter.
    (i) Results of source water E. coli and Cryptosporidium monitoring.
    (ii) Initial bin classification for each system that currently 
provides filtration or that is unfiltered and required to install 
filtration, along with any change in bin classification due to 
watershed assessment during sanitary surveys or the second round of 
source water monitoring.
    (iii) A determination of whether each system that is unfiltered and 
meets all the filtration avoidance criteria of Sec.  141.71 of this 
chapter has a mean source water Cryptosporidium level above 0.01 
oocysts/L, along with any changes in this determination due to the 
second round of source water monitoring.
    (iv) The treatment or control measures that systems use to meet 
their Cryptosporidium treatment requirements under Sec.  141.720 or 
Sec.  141.721 of this section.
    (v) A list of systems required to cover or treat the effluent of an 
uncovered finished water reservoir.
    (vi) A list of systems for which the State has waived the 
requirement to cover or treat the effluent of uncovered finished water 
storage facilities and supporting documentation of the risk mitigation 
plan.
* * * * *
    7. Section 142.15 is amended by adding paragraph (c)(6) to read as 
follows:


Sec.  142.15  Reports by States.

    (c) * * *
    (6) Subpart W. (i) The initial bin classification for each system 
that currently provides filtration or that is unfiltered and required 
to install filtration, along with any change in bin classification due 
to watershed assessment during sanitary surveys or the second round of 
source water monitoring.
    (ii) A determination of whether each system that is unfiltered and 
meets all the filtration avoidance criteria of Sec.  141.71 of this 
chapter has a mean source water Cryptosporidium level above 0.01 
oocysts/L, along with any changes in this determination due to the 
second round of source water monitoring.
* * * * *
    8. Section 142.16 is amended by adding paragraphs (m) and (n) to 
read as follows:


Sec.  142.16  Special primacy conditions.

* * * * *
    (m) [Reserved]
    (n) Requirements for States to adopt 40 CFR part 141, subpart W. In 
addition to the general primacy requirements elsewhere in this part, 
including the requirements that State regulations be at least as 
stringent as federal requirements, an application for approval of a 
State program revision that adopts 40 CFR part 141, subpart W,

[[Page 47795]]

must contain a description of how the State will accomplish the 
following program requirements where allowed in State programs.
    (1) Assess significant changes in the watershed and source water as 
part of the sanitary survey process and determine appropriate follow-up 
action.
    (2) Approve watershed control programs for the 0.5 log watershed 
control program credit in the microbial toolbox.
    (3) Approval protocols for treatment credits under the 
Demonstration of Performance toolbox option and for alternative ozone 
and chlorine dioxide CT values.
    (4) Determine that a system with an uncovered finished water 
reservoir has a risk mitigation plan that is adequate for purposes of 
waiving the requirement to cover or treat the reservoir.
[FR Doc. 03-18295 Filed 8-8-03; 8:45 am]
BILLING CODE 6560-50-P