[Federal Register Volume 68, Number 159 (Monday, August 18, 2003)]
[Proposed Rules]
[Pages 49548-49681]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-18149]



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Part II





Environmental Protection Agency





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40 CFR Parts 141, 142, and 143



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National Primary Drinking Water Regulations: Stage 2 Disinfectants and 
Disinfection Byproducts Rule; National Primary and Secondary Drinking 
Water Regulations: Approval of Analytical Methods for Chemical 
Contaminants; Proposed Rule

  Federal Register / Vol. 68, No. 159 / Monday, August 18, 2003 / 
Proposed Rules  

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 141, 142 and 143

[FRL-7530-3]
RIN 2040-AD38


National Primary Drinking Water Regulations: Stage 2 
Disinfectants and Disinfection Byproducts Rule; National Primary and 
Secondary Drinking Water Regulations: Approval of Analytical Methods 
for Chemical Contaminants

AGENCY: Environmental Protection Agency.

ACTION: Proposed rule.

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SUMMARY: In this document, the Environmental Protection Agency (EPA) is 
proposing maximum contaminant level goals (MCLGs) for chloroform, 
monochloroacetic acid (MCAA) and trichloroacetic acid (TCAA); National 
Primary Drinking Water Regulations (NPDWRs) which consist of maximum 
contaminant levels (MCLs) and monitoring, reporting, and public 
notification requirements for total trihalomethanes (TTHM--a sum of 
chloroform, bromodichloromethane, dibromochloromethane, and bromoform) 
and haloacetic acids (HAA5--a sum of mono-, di-, and trichloroacetic 
acids and mono- and dibromoacetic acids); and revisions to the reduced 
monitoring requirements for bromate. This document also specifies the 
best available technologies (BATs) for the proposed MCLs. EPA is also 
proposing additional analytical methods for the determination of 
disinfectants and disinfection byproducts (DBPs) in drinking water and 
proposing to extend approval of DBP methods for the determination of 
additional chemical contaminants. This set of regulations proposed 
today is known as the Stage 2 Disinfectants and Disinfection Byproducts 
Rule (Stage 2 DBPR). EPA's objective for the Stage 2 DBPR is to reduce 
the potential risks of reproductive and developmental health effects 
and cancer associated with disinfection byproducts (DBPs) by reducing 
peak and average levels of DBPs in drinking water supplies.
    The Stage 2 DBPR applies to public water systems (PWS) that are 
community water systems (CWSs) or nontransient noncommunity water 
systems (NTNCWs) that add a primary or residual disinfectant other than 
ultraviolet light or deliver water that has been treated with a primary 
or residual disinfectant other than ultraviolet light.

DATES: The Agency requests comments on today's proposal. Comments must 
be received or post-marked by midnight November 17, 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-2002-0043. 
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 Tom 
Grubbs, Office of Ground Water and Drinking Water (MC 4607M), U.S. 
Environmental Protection Agency, 1200 Pennsylvania Ave., NW., 
Washington, DC 20460; telephone (202) 564-5262. 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 Stage 2 DBPR are community 
and nontransient noncommunity water systems that add a primary or 
residual disinfectant other than ultraviolet light or deliver water 
that has been treated with a primary or residual disinfectant other 
than ultraviolet light. Regulated categories and entities are 
identified in the following chart.

------------------------------------------------------------------------
           Category                  Examples of regulated entities
------------------------------------------------------------------------
Industry.....................  Community and nontransient noncommunity
                                water systems that add a primary or
                                residual disinfectant other than
                                ultraviolet light or deliver water that
                                has been treated with a primary or
                                residual disinfectant other than
                                ultraviolet light.
State, Local, Tribal, or       Community and nontransient noncommunity
 Federal Governments.           water systems that add a primary or
                                residual disinfectant other than
                                ultraviolet light or deliver water that
                                has been treated with a primary or
                                residual disinfectant other than
                                ultraviolet light.
------------------------------------------------------------------------

    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 of which EPA is now 
aware that 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.  
141.2 and the section entitled ``coverage'' (Sec.  141.3) in Title 40 
of the Code of Federal Regulations and applicability criteria in Sec.  
141.600 and 141.620 of today's proposal. If you have questions 
regarding the applicability of the Stage 2 DBPR to a particular entity, 
contact 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-2002-0043. 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/.

[[Page 49549]]

    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 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-2002-0043. 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-2002-0043. 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-2002-0043.
    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-2002-0043. 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 
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
ALT Alanine aminotransferase
AST Aspartate aminotransferase
ASTM American Society for Testing and Materials
AWWA American Water Works Association
AwwaRF American Water Works Association Research Foundation
BAT Best available technology
BCAA Bromochloroacetic acid

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BDCM Bromodichloromethane
CWS Community water system
DBAA Dibromoacetic acid
DBCM Dibromochloromethane
DBP Disinfection byproduct
DBPR Disinfectants and Disinfection Byproducts Rule
DCAA Dichloroacetic acid
DOC Dissolved organic carbon
EA Economic analysis
EC Enhanced coagulation
EDA Ethylenediamine
ED10 Maximum likelihood estimate of a dose producing effects 
in 10 percent of animals
EPA United States Environmental Protection Agency
FACA Federal Advisory Committee Act
FBRR Filter Backwash Recycling Rule
GAC Granular activated carbon
GC/ECD Gas chromatography using electron capture detection
GWUDI Ground water under the direct influence of surface water
HAA5 Haloacetic acids (five) (sum of monochloroacetic acid, 
dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and 
dibromoacetic acid)
IC Ion chromatography
ICR Information Collection Request
IC/ICP-MS Ion chromatograph--coupled to an inductively coupled plasma 
mass spectrometer
IDSE Initial distribution system evaluation
ILSI International Life Sciences Institute
IESWTR Interim Enhanced Surface Water Treatment Rule
IPCS International Programme on Chemical Safety
IRIS Integrated Risk Information System (EPA)
kWh/yr Kilowatt hours per year
LED10 Lower 95 percent confidence bound of the maximum 
likelihood estimate of the dose producing effects in 10 percent of 
animals
LH Luteinizing hormone
LOAEL Lowest observed adverse effect level
LRAA Locational running annual average
LT1ESWTR Long Term 1 Enhanced Surface Water Treatment Rule
LT2ESWTR Long Term 2 Enhanced Surface Water Treatment Rule
MBAA Monobromoacetic acid
MCAA Monochloroacetic acid
MCL Maximum contaminant level
MCLG Maximum contaminant level goal
M-DBP Microbial and disinfection byproducts
mg/L Milligram per liter
MRL Minimum reporting level
MRDL Maximum residual disinfectant level
MRDLG Maximum residual disinfectant level goal
MTBE Methyl tertiary butyl ether
mWh Megawatt-hours
NATICH National Air Toxics Information Clearinghouse
NDIR Nondispersive infrared detection
NDMA N-nitrosodimethylamine
NDWAC National Drinking Water Advisory Council
NF Nanofiltration
NOAEL No Observed Adverse Effect Level
NODA Notice of data availability
NPDWR National primary drinking water regulation
NRWA National Rural Water Association
NTNCWS Nontransient noncommunity water system
NTP National Toxicology Program
NTTAA National Technology Transfer and Advancement Act
ODA o-dianisidine dihydrochloride
OMB Office of Management and Budget
OSTP Office of Science and Technology Policy
PAR Population attributable risk
PE Performance evaluation
PWS Public water system
QC Quality control
RAA Running annual average
RFA Regulatory Flexibility Act
RfD Reference dose
RSC Relative source contribution
RSD Relative standard deviation
SAB Science Advisory Board
SAC Selective anion concentration
SBAR Small Business Advisory Review
SBREFA Small Business Regulatory Enforcement Fairness Act
SDWA Safe Drinking Water Act, or the ``Act,'' as amended in 1996
SER Small Entity Representative
SGA Small for gestational age
SUVA Specific ultraviolet absorbance
SWAT Surface Water Analytical Tool
SWTR Surface Water Treatment Rule
TAME Tertiary amyl methyl ether
TCAA Trichloroacetic acid
TCR Total Coliform Rule
THM Trihalomethane
TOC Total organic carbon
TTHM Total trihalomethanes (sum of four THMs: chloroform, 
bromodichloromethane, dibromochloromethane, and bromoform)
TWG Technical work group
UMRA Unfunded Mandates Reform Act
USDOE EIA U.S. Department of Energy, Energy Information Administration
UV 254 Ultraviolet absorption at 254 nm
WTP Willingness To Pay

Table of Contents

I. Summary
    A. Why is EPA Proposing the Stage 2 DBPR?
    B. What Does the Stage 2 DBPR Require?
    C. What are the Economic Impacts of the Stage 2 DBPR?
II. Background
    A. What is the Statutory Authority for the Stage 2 DBPR?
    B. What is the Regulatory History of the Stage 2 DBPR?
    C. How were Stakeholders Involved in Developing the Stage 2 
DBPR?
    1. Federal Advisory Committee process
    2. Other outreach processes
III. Public Health Risk
    A. Reproductive and Developmental Epidemiology
    1. Reif et al. 2000
    a. Fetal growth
    b. Fetal viability
    c. Fetal malformations and other developmental anomalies
    2. Bove et al. 2002
    a. Fetal growth
    b. Fetal viability
    c. Fetal malformations
    3. Nieuwenhuijsen et al. 2000
    4. Additional epidemiology studies
    B. Reproductive and Developmental Toxicology
    1. EPA analysis and research
    2. Tyl, 2000
    a. Developmental defects
    b. Whole litter resorption
    c. Fetal toxicity
    d. Male reproductive effects
    3. World Health Organization review of the reproductive and 
developmental toxicology literature (2000)
    4. New Studies
    C. Conclusions Drawn from the Reproductive and Developmental 
Health Effects Data
    D. Cancer Epidemiology
    1. Population Attributable Risk analysis
    2. New epidemiological cancer studies
    a. New bladder cancer studies
    b. New colon cancer studies
    c. New rectal cancer studies
    d. Other cancers
    3. Review of the cancer epidemiology literature (WHO 2000)
    E. Cancer and Other Toxicology
    1. EPA criteria documents
    2. Other byproducts with carcinogenic potential
    a. 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) (MX)--
multisite cancer
    b. N-nitrosodimethylamine (NDMA)--multisite cancer
    3. Other toxicological effects
    4. WHO review of the cancer toxicology literature (2000)
    F. Conclusions Drawn from the Cancer Epidemiology and Toxicology
    G. Request for Comment
IV. DBP Occurrence within Distribution Systems
    A. Data Sources
    1. Information Collection Rule Data
    2. Other Data Sources Used to Support the Proposal
    B. DBPs in Distribution Systems

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    1. DBPs above the MCL occur at some locations in a substantial 
number of plants
    2. Specific locations in distribution systems are not protected 
to MCL levels
    3. Stage 1 DBPR maximum residence time location may not reflect 
the highest DBP occurrence levels
    C. Request for Comment
V. Discussion of Proposed Stage 2 DBPR Requirements
    A. MCLG for Chloroform
    1. What is EPA proposing today?
    2. How was this proposal developed?
    a. Background
    b. Basis of the new chloroform MCLG
    i. Mode of action
    ii. Metabolism
    c. How the MCLG is derived
    i. Reference dose
    ii. Relative source contribution
    iii. Water ingestion and body weight assumptions
    iv. MCLG calculation
    v. Other considerations
    d. Feasibility of other options
    3. Request for comment
    B. MCLGs for THMs and HAAs
    1. What is EPA proposing today?
    2. How was this proposal developed?
    a. Trichloroacetic acid
    b. Monochloroacetic acid
    3. Request for comment
    C. Consecutive Systems
    1. What is EPA proposing today?
    a. Definitions
    b. Monitoring
    c. Compliance schedules
    d. Treatment
    e. Violations
    f. Public notice and consumer confidence reports
    g. Recordkeeping and reporting
    h. State special primacy conditions
    2. How was this proposal developed?
    3. Request for comment
    D. MCLs for TTHM and HAA5
    1. What is EPA proposing today?
    2. How was this proposal developed?
    a. Definition of an LRAA
    b. Consideration of regulatory alternatives
    c. Basis for the LRAA
    d. Basis for phasing LRAA compliance
    e. TTHM and HAA5 as Indicators
    3. Request for comment
    E. Requirements for Peak TTHM and HAA5 Levels
    1. What is EPA proposing today?
    2. How was this proposal developed?
    3. Request for comment
    F. BAT for TTHM and HAA5
    1. What is EPA proposing today?
    2. How was this proposal developed?
    a. Basis for the BAT
    i. BAT analysis using the Information Collection Rule treatment 
studies
    ii. BAT analysis using the SWAT
    b. Basis for the Consecutive System BAT
    3. Request for comment
    G. MCL, BAT, and Monitoring for Bromate
    1. What is EPA proposing today?
    2. How was this proposal developed?
    a. Bromate MCL
    b. Bromate in hypochlorite solutions
    c. Criterion for reduced bromate monitoring
    3. Request for comment
    H. Initial Distribution System Evaluation (IDSE)
    1. What is EPA proposing today?
    a. Applicability
    b. Data collection
    i. Standard monitoring program
    ii. System specific study
    iii. 40/30 certification
    c. Implementation
    2. How was this proposal developed?
    a. Applicability
    b. Data collection
    c. Implementation
    3. Request for comment
    a. Applicability
    b. Data collection
    c. Implementation
    I. Monitoring Requirements and Compliance Determination for 
Stage 2A and Stage 2B TTHM and HAA5 MCLs
    1. What is EPA proposing today?
    a. Stage 2A
    b. IDSE
    c. Stage 2B
    i. Subpart H systems serving 10,000 or more people
    ii. Subpart H systems serving 500 to 9,999 people
    iii. Subpart H systems serving fewer than 500 people
    iv. Ground water systems serving 10,000 or more people
    v. Ground water systems serving fewer than 10,000 people
    vi. Consecutive systems
    2. How was this proposal developed?
    a. Sampling intervals for quarterly monitoring
    b. Reduced monitoring frequency
    c. Different IDSE sampling locations by disinfectant type
    d. Population-based monitoring requirements for certain 
consecutive systems
    3. Request for comment
    a. Proposed IDSE and Stage 2B monitoring requirements
    b. Plant-based vs. population-based monitoring requirements
    i. Issues with plant-based monitoring requirements
    ii. Approaches to addressing issues with plant-based monitoring
    J. Compliance Schedules
    1. What is EPA proposing?
    2. How did EPA develop this proposal?
    3. Request for comments
    K. Public Notice Requirements
    1. What is EPA proposing?
    2. Request for comments
    L. Variances and Exemptions
    1. Variances
    2. What are the affordable treatment technologies for small 
systems?
    M. Requirements for Systems to Use Qualified Operators
    N. System Reporting and Recordkeeping Requirements
    1. Confirmation of applicable existing requirements
    2. Summary of additional reporting requirements
    3. Request for comment
    O. Analytical Method Requirements
    1. What is EPA proposing today?
    2. How was this proposal developed?
    3. Which new methods are proposed for approval?
    a. EPA Method 327.0 for chlorine dioxide and chlorite.
    b. EPA Method 552.3 for HAA5 and dalapon
    c. ASTM D 6581-00 for bromate, chlorite, and bromide
    d. EPA Method 317.0 revision 2 for bromate, chlorite, and 
bromide
    e. EPA Method 326.0 for bromate, chlorite, and bromide
    f. EPA Method 321.8 for bromate
    g. EPA 415.3 for TOC and SUVA (DOC and UV254)
    4. What additional regulated contaminants can be monitored by 
extending approval of EPA Method 300.1?
    5. Which methods in the 20th edition and 2003 On-Line Version of 
Standard Methods are proposed for approval?
    6. What is the updated citation for EPA Method 300.1?
    7. How is the HAA5 sample holding time being standardized?
    8. How is EPA clarifying which methods are approved for 
magnesium determinations?
    9. Which methods can be used to demonstrate eligibility for 
reduced bromate monitoring?
    10. Request for comments
    P. Laboratory Certification and Approval
    1. What is EPA proposing today?
    2. What changes are proposed for the PE acceptance criteria?
    3. What minimum reporting limits are being proposed?
    4. What are the requirements for analyzing IDSE samples?
    5. Request for comments
VI. State Implementation
    A. State Primacy Requirements for Implementation Flexibility
    B. State Recordkeeping Requirements
    C. State Reporting Requirements
    D. Interim Primacy
    E. IDSE Implementation
    F. State Burden
VII. Economic Analysis
    A. Regulatory Alternatives Considered by the Agency
    B. Rationale for the Proposed Rule Option
    1. Reducing peak exposure
    2. Reducing average exposure
    C. Benefits of the Proposed Stage 2 DBPR
    1. Non-quantifiable health and non-health related benefits
    2. Quantifiable health benefits
    3. Benefit sensitivity analyses
    D. Costs of the Proposed Stage 2 DBPR
    1. National cost estimates
    2. Water system costs
    3. State costs
    4. Non-quantifiable
    E. Expected System Treatment Changes
    1. Pre-Stage 2 DBPR baseline conditions
    2. Predicted technology distributions post-Stage 2 DBPR
    F. Estimated Household Costs of the Proposed Rule
    G. Incremental Costs and Benefits of the Proposed Stage 2 DBPR
    H. Benefits From the Reduction of Co-Occurring Contaminants

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    I. Are there Increased Risks From Other Contaminants?
    J. Effects on General Population and Subpopulation Groups
    K. Uncertainties in Baseline, Risk, Benefit, and Cost Estimates
    L. Benefit/Cost Determination for the Proposed Stage 2 DBPR
    M. Request for Comment
VIII. 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
    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
    K. Consultations with the Science Advisory Board, National 
Drinking Water Advisory Council, and the Secretary of Health and 
Human Services
    L. Plain Language
IX. References

I. Summary

A. Why Is EPA Proposing the Stage 2 DBPR?

    The Environmental Protection Agency is committed to ensuring that 
all public water systems provide clean and safe drinking water. 
Disinfectants are often an essential element of drinking water 
treatment because of the barrier they provide against harmful 
waterborne microbial pathogens. However, disinfectants react with 
naturally occurring organic and inorganic matter in source water and 
distribution systems to form disinfection byproducts (DBPs) that may 
pose health risks. The Agency is proposing the Stage 2 Disinfectants 
and Disinfection Byproduct Rule (DBPR) to reduce potential cancer, 
reproductive, and developmental risks from DBPs.
    The Stage 2 DBPR augments the Stage 1 DBPR that was finalized in 
1998. The proposed Stage 2 DBPR focuses on monitoring and reducing 
concentrations of two classes of DBPs: total trihalomethanes (TTHM) and 
haloacetic acids (HAA5). In part, these two groups of DBPs are used as 
indicators of the various byproducts that are present in disinfected 
water. This means that concentrations of TTHM and HAA5 are monitored 
for compliance, but their presence in drinking water is representative 
of many other DBPs that may also be present in the water; likewise, a 
reduction in TTHM and HAA5 indicates a reduction of total DBPs.
    The Stage 2 DBPR is designed to reduce the level of exposure from 
disinfectants and DBPs without undermining the control of microbial 
pathogens. The Long Term 2 Enhanced Surface Water Treatment Rule 
(LT2ESWTR) will be finalized and implemented simultaneously with the 
Stage 2 DBPR to ensure that drinking water is microbiologically safe at 
the limits set for disinfectants and DBPs.
    New information on health effects, occurrence, and treatment has 
become available since the Stage 1 DBPR, which supports the need for 
the Stage 2 DBPR. Several reproductive and developmental studies have 
recently become available, and EPA has completed a more extensive 
analysis of reproductive and developmental effects associated with DBPs 
since the Stage 1 DBPR. Both human epidemiology studies and animal 
toxicology studies have shown associations between chlorinated drinking 
water and reproductive and developmental endpoints such as spontaneous 
abortion, stillbirth, neural tube defects, pre-term delivery, 
intrauterine growth retardation, and low birth weight. New epidemiology 
and toxicology studies evaluating bladder and rectal cancers have also 
increased the weight of evidence linking these health effects to DBP 
exposure. The large number of people (254 million Americans) exposed to 
DBPs and the identified potential cancer, reproductive, and 
developmental risks played a significant role in EPA's decision to move 
forward with regulatory changes that target lowering DBP exposures 
beyond the requirements of the Stage 1 DBPR.
    While the Stage 1 DBPR provided a major reduction in DBP exposure, 
new national survey data suggest that some customers are receiving 
drinking water with elevated, or peak DBP concentrations even when 
their distribution systems are in compliance with the Stage 1 DBPR. 
Some of these peak concentrations can be substantially greater than the 
Stage 1 DBPR maximum contaminant levels (MCLs). The new survey results 
also showed that Stage 1 DBPR monitoring sites may not be 
representative of peak DBP concentrations that occur in distribution 
systems. In addition, the new information indicates that cost-effective 
technologies including ultraviolet light (UV) and granular activated 
carbon (GAC) may be very effective at lowering DBP levels. EPA's 
analysis of this new information concludes that significant public 
health benefits may be achieved through further cost-effective 
reduction of DBPs in distribution systems.
    Congress required EPA to promulgate the Stage 2 DBPR as part of the 
1996 Safe Drinking Water Act (SDWA) Amendments (section 1412(b)(2)(C)). 
Today's proposal reflects consensus recommendations from the Stage 2 
Microbial/Disinfection Byproducts (M-DBP) Federal Advisory Committee 
(the Advisory Committee). These recommendations are set forth in the M-
DBP Agreement in Principle (USEPA 2000g), which can be accessed on the 
edocket Web site (www.epa.gov/edocket).
    After considering the new occurrence and health effects data and 
analyses, EPA has determined that there is an opportunity to further 
reduce potential risks from DBPs. The Stage 2 DBPR being proposed today 
presents a cost-effective, risk targeting approach to reduce risks from 
DBPs. The new requirements provide for more consistent protection from 
DBPs across the entire distribution system and the reduction of DBP 
peaks. New risk targeting provisions require only those systems with 
the greatest risk to make capital improvements. The Stage 2 DBPR, in 
conjunction with the LT2ESWTR, will help public water systems deliver 
safer water to Americans with the benefits of disinfection to control 
pathogens but with fewer risks from DBPs.

B. What Does the Stage 2 DBPR Require?

    The Stage 2 DBPR applies to community or nontransient noncommunity 
water systems that add a primary or residual disinfectant other than 
ultraviolet light or deliver water that has been treated with a primary 
or residual disinfectant other than ultraviolet light. The TTHM and 
HAA5 MCL values will remain the same as in the Stage 1 DBPR, although 
compliance calculations will be different. The proposed Stage 2 DBPR 
includes new MCLGs for chloroform, monochloroacetic acid, and 
trichloroacetic acid, but these new MCLGs do not affect the MCLs for 
TTHM or HAA5.
    The risk targeting components of the Stage 2 DBPR will focus the 
greatest amount of change where the greatest amount of risk may exist. 
The provisions of the Stage 2 DBPR focus on identifying and reducing 
exposure by reducing DBP peaks in distribution systems. The first 
provision, designed to address significant variations in exposure, is 
the Initial Distribution System Evaluation (IDSE). The purpose

[[Page 49553]]

of the IDSE is to identify Stage 2 DBPR compliance monitoring sites for 
capturing peaks. Because Stage 2 DBPR compliance will be determined at 
these new monitoring sites, distribution systems that identify elevated 
concentrations of TTHM and HAA5 will need to make treatment or process 
changes to bring the system into compliance with the Stage 2 DBPR. By 
identifying compliance monitoring sites with elevated concentrations of 
TTHM and HAA5, the IDSE will offer increased assurance that MCLs are 
being met across the distribution system. Both treatment changes and 
awareness of TTHM and HAA5 levels resulting from the IDSE will allow 
systems to better control for distribution system peaks.
    The IDSE is designed to offer flexibility to public water systems. 
The IDSE requires TTHM and HAA5 monitoring for one year on a regular 
schedule that is determined by source water type and system size. 
Systems have the option of performing a site-specific study based on 
historical data, water distribution system models, or other data; and 
waivers are available under certain circumstances. The proposed IDSE 
requirements are discussed in sections V.H., V.I., and V.J. of this 
preamble and in subpart U of the proposed rule.
    The second provision of the Stage 2 DBPR, which is designed to 
address variations in temporal and spatial exposure, is the new 
compliance calculation of the MCLs. The Stage 1 DBPR running annual 
average (RAA) calculation allows some locations within a distribution 
system to have higher DBP annual averages than others as long as the 
system-wide average is below the MCL. The Stage 2 DBPR will base 
compliance on a locational running annual average (LRAA) calculation 
where the annual average at each sampling location in the distribution 
system will be used to determine compliance with the MCLs. The LRAA 
will reduce exposures to peak DBP concentrations by ensuring that each 
monitoring site is in compliance with the MCLs as an annual average, 
and it will provide all customers drinking water that more consistently 
meets the MCLs.
    EPA is proposing that systems comply with the Stage 2 DBPR MCLs in 
two phases, designated as Stage 2A and Stage 2B. In Stage 2A, beginning 
three years after the rule is final, all systems must comply with MCLs 
of 0.120 mg/L for TTHM and 0.100 mg/L for HAA5 as LRAAs at Stage 1 DBPR 
sampling sites, in addition to continuing to comply with the Stage 1 
DBPR MCLs of 0.080 mg/L and 0.060 mg/L as RAAs for TTHM and HAA5, 
respectively. In Stage 2B, systems must comply with MCLs of 0.080 mg/L 
and 0.060 mg/L as LRAAs for TTHM and HAA5, respectively, based on 
sampling sites identified through the IDSE. A more detailed discussion 
of the proposed Stage 2 DBPR MCL requirements can be found in sections 
V.D., V.I., and V.J. of this preamble and in Sec.  141.64(b)(2) and 
(3), and Sec.  141.136, and subpart V of the rule language.
    The IDSE and LRAA calculation will lead to overall reductions in 
DBP concentrations and reduce short term exposures to high DBP 
concentrations, but even with this strengthened approach to regulating 
DBPs it will be possible for individual DBP samples to exceed the MCLs 
when systems are in compliance with the Stage 2 DBPR. The Stage 2 DBPR 
requires systems that experience significant excursions to evaluate 
distribution system operational practices and identify opportunities to 
reduce DBP concentrations in the distribution system. This provision 
will curtail peaks and reduce exposure to high DBP levels. Significant 
excursions are discussed in greater detail in section V.E.
    The Stage 2 DBPR also contains provisions for regulating 
consecutive systems, defined in the Stage 2 DBPR as public water 
systems that buy or otherwise receive some or all of their finished 
water from another public water system on a regular basis. Uniform 
regulation of consecutive systems provided by the Stage 2 DBPR will 
ensure that consecutive systems deliver drinking water that meets 
applicable DBP standards. More information on regulation of consecutive 
systems can be found in sections V.C., V.H., V.I. and V.J.
    Today's document proposes plant-based monitoring requirements for 
non-consecutive systems and certain consecutive systems. Plant-based 
monitoring means that the number of compliance monitoring locations 
within a distribution system is based on the number of plants, 
population served, and type of source water used by the distribution 
system. EPA is proposing population-based monitoring for consecutive 
systems that buy all their finished water from other public water 
systems. EPA is also requesting comment on whether this approach should 
be extended to all systems covered by today's rule. Under a population-
based monitoring structure, the number of compliance monitoring 
locations is based only on the population served and source water type. 
Section V.I. describes population-based monitoring and how it might 
affect systems complying with this rule.

C. What Are the Economic Impacts of the Stage 2 DBPR?

    EPA quantified the potential benefits of the Stage 2 DBPR by 
estimating the reduction in bladder cancer cases that may result from 
the decrease in average DBP concentrations in disinfected water. 
Estimated reductions in DBP-related bladder cancers (including both 
fatal and non-fatal cases) result in annualized benefits ranging from 
$0 to $986 million (using a three percent discount rate), depending on 
the risk level assumed.
    There may also be a number of important nonquantifiable benefits 
associated with reducing DBPs in drinking water, the primary ones being 
reduced potential risk of adverse reproductive and developmental 
effects including miscarriage, stillbirth, neural tube defects, heart 
defects, and cleft palate. Although a number of studies have found an 
association between reproductive and developmental endpoints and short-
term exposure to elevated DBP levels, a causal link has not yet been 
established and information is not yet available to quantify potential 
effects. As a result, the Agency has not included an estimate of the 
potential benefits from reducing reproductive and developmental risks 
in its primary economic impact analysis of the Stage 2 DBPR. However, 
an illustrative calculation of potential fetal loss risk is discussed 
in Section VII and presented in more detail in the Economic Analysis 
(USEPA 2003i) to illustrate the benefits that could be associated with 
this rule. Reduction in other cancers potentially associated with DBP 
exposure represent additional unquantified health benefits.
    EPA estimates the total annualized costs of the Stage 2 DBPR to be 
$54 to $64 million. This estimate includes costs associated with 
treatment changes, the Initial Distribution System Evaluation, changes 
in compliance monitoring, and rule implementation activities for both 
public water systems and States. EPA estimates that approximately 2.8 
percent of all plants will need to convert to chloramines or add 
advanced treatment to comply with the Stage 2 DBPR.
    Table I-1 presents the estimated quantified and unquantified 
benefits of the Stage 2 DBPR and the estimated costs. Analyses of 
unquantified benefits suggest that the total benefits associated with 
the Stage 2 DBPR might be much greater than these estimates. By 
targeting risks and building on the solid foundation of the Stage 1 
DBPR, the

[[Page 49554]]

Stage 2 DBPR will deliver cost-effective reductions in DBP levels and 
associated potential public health risks.

          Table I-1.--Costs and Benefits of the Stage 2 DBPR Based on Annualization Discount Rate of 3%
----------------------------------------------------------------------------------------------------------------
                  Costs                       Benefits                     Unquantified benefits
----------------------------------------------------------------------------------------------------------------
$54-64 M.................................        $0-986 M  Reduction in potential reproductive and developmental
                                                            health effects, potential reduction in colon and
                                                            rectal cancer, improved taste and odor of drinking
                                                            water, control of contaminants that may be regulated
                                                            in the future.
----------------------------------------------------------------------------------------------------------------

II. Background

    A combination of factors have influenced the development of the 
proposed Stage 2 DBPR. These include the initial 1992-1994 Microbial 
and Disinfection Byproduct (M-DBP) stakeholder deliberations and EPA's 
Stage 1 DBPR proposal; the 1996 Safe Drinking Water Act (SDWA) 
Amendments; the 1996 Information Collection Rule; the 1998 Stage 1 
DBPR; other new data, research, and analysis on disinfection byproduct 
(DBP) occurrence, treatment, and health effects since the Stage 1 DBPR; 
and the Stage 2 DBPR Microbial and Disinfection Byproducts Federal 
Advisory Committee. The following shows how EPA arrived at this 
proposal for regulating disinfection byproducts.

A. What Is the Statutory Authority for the Stage 2 DBPR?

    The SDWA, as amended in 1996, authorizes EPA to promulgate a 
national primary drinking water regulation (NPDWR) and publish a 
maximum contaminant level goal (MCLG) for contaminants 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 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 public water systems'' (SDWA section 1412(b)(1)(A)). MCLGs 
are non-enforceable health goals set at a level at which ``no known or 
anticipated adverse effects on the health of persons occur and which 
allows an adequate margin of safety''. These health goals are published 
at the same time as the NPDWR (sections 1412(b)(4) and 1412(a)(3)).
    The Agency may also consider additional health risks from other 
contaminants and establish an MCL ``at a level other than the feasible 
level, if the technology, treatment techniques, and other means used to 
determine the feasible level would result in an increase in the health 
risk from drinking water by--(i) increasing the concentration of other 
contaminants in drinking water; or (ii) interfering with the efficacy 
of drinking water treatment techniques or processes that are used to 
comply with other national primary drinking water regulations'' 
(section 1412(b)(5)(A)). When establishing an MCL or treatment 
technique under this authority, ``the level or levels of treatment 
techniques shall minimize the overall risk of adverse health effects by 
balancing the risk from the contaminant and the risk from other 
contaminants the concentrations of which may be affected by the use of 
a treatment technique or process that would be employed to attain the 
MCL or levels'' (section 1412(b)(5)(B)).
    Finally, section 1412(b)(2)(C) of the Act requires EPA to 
promulgate a Stage 2 DBPR 18 months after promulgation of the Long Term 
1 Enhanced Surface Water Treatment Rule (LT1ESWTR). Consistent with 
statutory requirements for risk balancing (section 1412(b)(5)(B)), EPA 
will finalize the LT2ESWTR concurrently with the Stage 2 DBPR to ensure 
simultaneous protection from microbial and DBP risks.

B. What Is the Regulatory History of the Stage 2 DBPR?

    The first rule to regulate DBPs was promulgated on November 29, 
1979. The Total Trihalomethanes Rule (44 FR 68624) (USEPA 1979) set an 
MCL of 0.10 mg/L for total trihalomethanes (TTHMs). Compliance was 
based on the running annual average (RAA) of quarterly averages of all 
samples collected throughout the distribution system. This TTHM 
standard applied only to community water systems using surface water 
and/or ground water that served at least 10,000 people and added a 
disinfectant to the drinking water during any part of the treatment 
process.
    Under the Surface Water Treatment Rule (SWTR) (54 FR 27486, June 
29, 1989) (USEPA 1989a), EPA set MCLGs of zero for Giardia lamblia, 
viruses, and Legionella; and promulgated NPDWRs for all public water 
systems using surface water sources or ground water sources under the 
direct influence of surface water. The SWTR includes treatment 
technique requirements for filtered and unfiltered systems that are 
intended to protect against the adverse health effects of exposure to 
Giardia lamblia, viruses, and Legionella, as well as other pathogenic 
organisms.
    EPA also promulgated the Total Coliform Rule (TCR) on June 29, 1989 
(54 FR 27544)(USEPA 1989b) to provide protection from microbial 
contamination in distribution systems of all types of public water 
supplies. The TCR 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. Under the TCR, no more 
than 5 percent of distribution system samples collected in any month 
may contain coliform bacteria.
    Together, the SWTR and the TCR were intended to address risks 
associated with microbial pathogens that might be found in source 
waters or associated with distribution systems. However, while reducing 
exposure to pathogenic organisms, the SWTR also increased the use of 
disinfectants in some public water systems and, as a result, exposure 
to DBPs in those systems.
    In 1992, prompted by concerns about health risk tradeoffs between 
disinfection byproducts and microbial pathogens, EPA initiated a 
negotiated rulemaking with a wide range of stakeholders. The 
negotiators included representatives of State and local health and 
regulatory agencies, public water systems, elected officials, consumer 
groups, and environmental groups. The Regulatory Negotiating Committee 
met from November 1992 through June 1993. Following months of intensive 
discussions and technical analyses, the Regulatory Negotiating 
Committee recommended the development of three sets of rules: an 
Information Collection Rule, a two-staged approach for regulating DBPs, 
and an ``interim'' Enhanced Surface Water Treatment Rule (IESWTR) to be 
followed by a ``final'' Enhanced Surface Water Treatment Rule (USEPA 
1996a, USEPA 1998c, USEPA 1998d). EPA took the first step towards 
implementing this strategy by proposing

[[Page 49555]]

the Stage 1 DBPR and IESWTR in 1994. Congress affirmed the phased 
microbial and disinfection byproduct rulemaking strategy in the 1996 
SDWA Amendments by requiring that EPA develop these three sets of rules 
on a specific schedule that stipulates simultaneous promulgation of 
requirements governing microbial protection and DBPs.
    In March 1997, the Agency established the Microbial and 
Disinfection Byproduct (M-DBP) Advisory Committee under the Federal 
Advisory Committee Act (FACA) to collect, share, and analyze new 
information and data available since the 1994 proposals of the Stage 1 
DBPR and the IESWTR, as well as to build consensus on the regulatory 
implications of the new information. The Advisory Committee consisted 
of 17 members representing EPA, State and local public health and 
regulatory agencies, local elected officials, drinking water suppliers, 
chemical and equipment manufacturers, and public interest groups. The 
Advisory Committee met five times in March through July 1997 to discuss 
issues related to the IESWTR and the Stage 1 DBPR. The Advisory 
Committee reached consensus on a number of major issues that were 
incorporated into the Stage 1 DBPR and the IESWTR.
    The Stage 1 DBPR and IESWTR, finalized in December 1998, were the 
first rules to be promulgated under the 1996 SDWA Amendments (USEPA 
1998c and 1998d). The Stage 1 DBPR applies to all community and 
nontransient noncommunity water systems that add a chemical 
disinfectant to water. The rule established maximum residual 
disinfectant level goals (MRDLGs) and enforceable maximum residual 
disinfectant level (MRDL) standards for three chemical disinfectants--
chlorine, chloramine, and chlorine dioxide; maximum contaminant level 
goals (MCLGs) for three THMs, two haloacetic acids (HAAs), bromate, and 
chlorite; and enforceable maximum contaminant level (MCL) standards for 
TTHM, five haloacetic acids (HAA5), chlorite, and bromate calculated as 
running annual averages (RAAs). The Stage 1 DBPR uses TTHMs and HAA5 as 
indicators of the various DBPs that are present in disinfected water. 
Under the Stage 1 DBPR, water systems that use surface water or ground 
water under the direct influence of surface water and use conventional 
filtration treatment are required to remove specified percentages of 
organic materials, measured as total organic carbon (TOC), that may 
react with disinfectants to form DBPs. Removal is achieved through 
enhanced coagulation or enhanced softening, unless a system meets 
alternative compliance criteria.
    EPA finalized the IESWTR at the same time as the Stage 1 DBPR to 
ensure simultaneous compliance and address risk tradeoff issues. The 
IESWTR applies to all water systems that use surface water or ground 
water under the direct influence of surface water that serve at least 
10,000 people. The purpose of the IESWTR is to improve control of 
microbial pathogens in drinking water, specifically the protozoan 
Cryptosporidium.
    The Filter Backwash Recycle Rule (FBRR) and the Long Term 1 
Enhanced Surface Water Treatment Rule (LT1ESWTR) round out the first 
group of regulations balancing microbial and DBP risks. EPA promulgated 
the FBRR in 2001 (USEPA 2001c) and the LT1ESWTR in 2002 (USEPA 2002b) 
to increase protection of finished drinking water supplies from 
contamination by Cryptosporidium and other microbial pathogens. The 
LT1ESWTR extends protection against Cryptosporidium and other disease-
causing microbes to water systems that use surface water or ground 
water under the direct influence of surface water that serve fewer than 
10,000 people. While the Ground Water Rule, proposed in May 2000, 
(USEPA 2000h) will add significant protection from pathogens in 
vulnerable ground water systems, it does not pose as many risk-risk 
tradeoff considerations as the surface water rules because only a small 
percentage of ground water systems subject to the Stage 2 DBPR have 
high DBP levels.
    EPA reconvened the Advisory Committee in March 1999 to develop 
recommendations on issues pertaining to the Stage 2 DBPR and LT2ESWTR. 
The Advisory Committee collected, developed, and evaluated new 
information that became available after the Stage 1 DBPR was published. 
The Information Collection Rule provided new data on DBP exposure, and 
control; it also included new data on occurrence and treatment of 
pathogens. The unprecedented amount of information collected under the 
Information Collection Rule was supplemented by a survey conducted by 
the National Rural Water Association, data provided by various States, 
the Water Utility Database (which contains data collected by the 
American Water Works Association), and Information Collection Rule 
Supplemental Surveys. This large body of data allowed the Advisory 
Committee to reach new conclusions regarding DBP exposure and new 
treatment options.
    After analyzing the data, the Advisory Committee reached three 
significant conclusions that led the Advisory Committee to recommending 
further control of DBPs in public water systems. The data from the 
Information Collection Rule show that the RAA compliance calculation 
allows elevated DBP levels to regularly occur at some locations in the 
system when the overall average at all locations is below the MCL. 
Customers served at those sampling locations that regularly exceed the 
MCLs are experiencing higher exposure compared to customers served at 
locations that consistently meet the MCLs.
    Second, the new data demonstrated how single samples can be 
substantially above the MCLs. The new information showed that it is 
possible for customers to receive drinking water with concentrations of 
DBPs up to 75% above the MCLs even when their water system is in 
compliance with the Stage 1 DBPR. Studies have shown that DBP exposure 
during short, critical time windows may adversely impact reproductive 
and developmental health.
    Third, data from the Information Collection Rule revealed that the 
highest TTHM and HAA5 levels are not always located at the maximum 
residence time monitoring sites specified by the Stage 1 DBPR. These 
sites were required for monitoring by the Stage 1 DBPR because previous 
data suggested that water in the distribution system for the maximum 
residence time would have the highest TTHM levels. The fact that the 
locations with the highest DBP levels varied in different public water 
systems indicates that the Stage 1 DBPR monitoring sites may not be 
representative of the high DBP concentrations that actually exist in 
distribution systems, and additional monitoring is needed to identify 
distribution system locations with elevated DBP levels. This 
information encouraged the Advisory Committee to recommend additional 
measures to identify locations with high LRAAs. Section IV provides a 
complete discussion of the new occurrence data.
    The analysis of the new data also indicates that certain 
technologies are effective at reducing DBP concentrations. Bench- and 
pilot-scale studies for granular activated carbon (GAC) and membrane 
technologies required by the Information Collection Rule provided 
information on the effectiveness of the two technologies. Other studies 
found UV light to be highly effective for inactivating Cryptosporidium 
and Giardia at low doses without promoting the formation of DBPs 
(Malley et al. 1996; Zheng et al.

[[Page 49556]]

1999). This new treatment information added to the treatment options 
available to utilities for controlling DBPs beyond the requirements of 
the Stage 1 DBPR.
    New data on the health effects of DBPs also influenced the Advisory 
Committee's recommendation to further regulate DBPs. Although bladder 
cancer risks were the focus of the Stage 1 M-DBP negotiations, 
potential reproductive and developmental health effects were central to 
the Stage 2 M-DBP Advisory Committee discussions. Recent human 
epidemiology studies and animal toxicology studies have both shown 
associations between chlorinated drinking water and reproductive and 
developmental health effects such as spontaneous abortion, stillbirth, 
neural tube defects, pre-term delivery, intrauterine growth 
retardation, and low birth weight. A critical review of the 
epidemiology literature pertaining to reproductive and developmental 
effects of exposure to DBPs completed in 2000 (Reif et al. 2000) 
concluded that ``the weight of evidence from the epidemiological 
studies also suggests that they [DBPs] are likely to be reproductive 
toxicants in humans under appropriate exposure conditions * * * and 
that measures aimed at reducing the concentrations of byproducts could 
have a positive impact on public health.''
    While there has been substantial research to date, the Advisory 
Committee recognized that significant uncertainty remains regarding the 
risk associated with DBPs in drinking water. The Advisory Committee 
carefully considered the analyses described previously, as well as 
costs and potential impacts on public water systems, and concluded that 
a targeted protective public health approach should be taken to address 
exposure to DBPs beyond the requirements of the Stage 1 DBPR. After 
reaching this conclusion, the Advisory Committee developed an Agreement 
in Principle (USEPA 2000g) that laid out their recommendations on how 
to further control DBPs in public water systems.
    In the Agreement in Principle, the Advisory Committee recommended 
maintaining the MCLs for TTHM and HAA5 at 0.080 mg/L and 0.060 mg/L 
respectively, but changing the compliance calculation in two phases to 
facilitate systems moving from the running annual average (RAA) 
calculation to a locational running annual average (LRAA) calculation. 
In the first phase, systems would continue to comply with the Stage 1 
DBPR MCLs as RAAs and, at the same time, comply with MCLs of 0.120 mg/L 
for TTHM and 0.100 mg/L for HAA5 calculated as LRAAs. RAA calculations 
average all samples collected within a distribution system over a one-
year period, but LRAA calculations average all samples taken at each 
individual sampling location in a distribution system during a one-year 
period. Systems would also carry out an Initial Distribution System 
Evaluation (IDSE) to select new compliance monitoring sites that more 
accurately reflect higher TTHM and HAA5 levels occurring in the 
distribution system. The second phase of compliance would require MCLs 
of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 calculated as LRAAs at 
individual monitoring sites identified through the IDSE.
    The Agreement in Principle also provided recommendations for 
simultaneous compliance with the LT2ESWTR so that the reduction of 
potential health hazards of DBPs does not compromise microbial 
protection. The recommendations for the LT2ESWTR included treatment 
requirements for Cryptosporidium based on the results of source water 
monitoring, a toolbox of options for providing additional treatment at 
high risk facilities, use of microbial indicators to reduce 
Cryptosporidium monitoring burden on small systems, and future 
monitoring to determine if source water quality remains constant after 
completion of initial monitoring. The Agreement also encouraged EPA to 
develop guidance and criteria to facilitate the use of UV light for 
compliance with drinking water disinfection requirements. The complete 
text of the Agreement in Principle (USEPA 2000g) can be found at the 
edocket Web site (http://www.epa.gov/edocket).
    After extensive analysis and investigation of available data and 
rule options considered by the Advisory Committee, EPA is proposing a 
Stage 2 DBPR control strategy that is consistent with the key elements 
of the Agreement in Principle signed in September 2000 by the 
participants in the Stage 2 M-DBP Advisory Committee. EPA determined 
that the risk-targeting measures recommended in the Agreement in 
Principle will require only those systems with the greatest risk to 
make treatment and operational changes and will maintain simultaneous 
protection from the potential health hazards of DBPs and microbial 
contaminants. EPA has carefully evaluated and expanded upon the 
recommendations of the Advisory Committee to more fully develop today's 
proposal. EPA also made simplifications where possible to minimize 
complications for public water systems as they transition to compliance 
with the Stage 2 DBPR while expanding public health protection. The 
proposed requirements of the Stage 2 DBPR are described in detail in 
section V of this preamble.

C. How Were Stakeholders Involved in Developing the Stage 2 DBPR?

1. Federal Advisory Committee Process
    The Stage 2 M-DBP Advisory Committee consisted of 21 organizational 
members representing EPA, State and local public health and regulatory 
agencies, local elected officials, Native American Tribes, large and 
small drinking water suppliers, chemical and equipment manufacturers, 
environmental groups, and other stakeholders. Technical support for the 
Advisory Committee's discussions was provided by a technical working 
group established by the Advisory Committee. The Advisory Committee 
held ten meetings to discuss issues pertaining to the Stage 2 DBPR and 
LT2ESWTR from September 1999 to July 2000 which were open to the 
public. There was also an opportunity for public comment at each 
meeting.
    In September 2000, the Advisory Committee signed the Agreement in 
Principle, a full statement of the consensus recommendations of the 
group. The agreement was published by EPA in a December 29, 2000 
Federal Register notice (65 FR 83015), together with the list of 
committee members and their organizations. The Agreement is divided 
into Parts A and B. The recommendations in each part stand alone and 
are independent of one another. The entire Advisory Committee reached 
consensus on Part A, which contains provisions that directly apply to 
the proposed Stage 2 DBPR and LT2ESWTR. The full Advisory Committee, 
with the exception of the National Rural Water Association (NRWA), also 
agreed to Part B, which has recommendations for future activities by 
EPA in the areas of distribution systems and microbial water quality 
criteria.
2. Other Outreach Processes
    EPA received valuable input from small system operators as part of 
an Agency outreach initiative under the Regulatory Flexibility Act 
(RFA). EPA also conducted outreach conference calls to solicit feedback 
and information from Small Entity Representatives (SERs) on issues 
related to Stage 2 DBPR impacts on small systems. The Agency consulted 
with State, local, and Tribal governments on the proposed Stage 2 DBPR. 
Section VIII includes a complete

[[Page 49557]]

description of the many stakeholder activities which contributed to the 
development of the Stage 2 DBPR.
    The Agency held two meetings to discuss consecutive system issues 
relevant to the proposal (February 22-23, 2001 in Denver, CO and March 
28, 2001 in Washington, DC). Representatives from States, EPA Regions, 
and public water systems participated in the discussions. EPA also 
briefed the National Drinking Water Advisory Committee at their 
November 2001 meeting on consecutive system issues associated with the 
rule to receive input on the implementation strategy selected. This 
Advisory Committee generally supported EPA's approach. Section V 
describes EPA's analysis of consecutive system issues, comments and 
input received during these sessions, and how the proposed requirements 
will apply to consecutive systems. EPA also consulted with the Science 
Advisory Board in December 2001 on the requirements of the Stage 2 
DBPR.
    Finally, EPA posted a pre-proposal draft of the Stage 2 DBPR 
preamble and regulatory language on an EPA Internet site (http://www.epa.gov/safewater/mdbp/st2dis.html) on October 17, 2001. This 
public review period allowed readers to comment on the Stage 2 DBPR's 
consistency with the Agreement in Principle of the Stage 2 M-DBP 
Advisory Committee. EPA received important suggestions on this pre-
proposal draft from 14 commenters which included public water systems, 
State governments, laboratories, and other stakeholders. While EPA will 
not formally respond to these comments, EPA has carefully considered 
them in developing today's proposal.

III. Public Health Risk

    Chlorine has been widely used as a chemical disinfectant, serving 
as a principal barrier to microbial contaminants in drinking water. 
However, the microbial risk reduction attributes of chlorination have 
been increasingly scrutinized due to concerns about potential increased 
health risks from exposure to disinfection byproducts, which are formed 
when certain disinfectants interact with organic and inorganic material 
in source waters. Since the discovery of chlorination byproducts in 
drinking water in 1974, numerous toxicological studies have shown 
several DBPs (e.g., bromodichloromethane, bromoform, chloroform, 
dichloroacetic acid, trichloroacetic acid and bromate) to be 
carcinogenic in laboratory animals. These findings of carcinogenicity 
influenced EPA to promulgate the TTHM Rule in 1979 and the Stage 1 DBPR 
in 1998. The Stage 1 DBPR primarily addressed possible carcinogenic 
effects (e.g., bladder, colon and rectal cancers) reported in both 
human epidemiology and laboratory animal studies. Since the Stage 1 
DBPR, new health studies continue to support an association between 
bladder, colon and rectal cancers from long-term exposure to 
chlorinated surface water. In addition to cancer effects, recent 
studies have reported associations between use of chlorinated drinking 
water and a number of reproductive and developmental endpoints 
including spontaneous abortion, still birth, neural tube defect, pre-
term delivery, low birth weight and intrauterine growth retardation 
(small for gestational age). Short-term, high-dose animal screening 
studies on individual byproducts (e.g., bromodichloromethane (BDCM), 
and certain haloacetic acids) have also reported adverse reproductive 
and developmental effects (e.g., whole litter resorption, reduced fetal 
body weight) that are similar to those reported in the human 
epidemiology studies. This section discusses the new studies that have 
become available since promulgation of the Stage 1 DBPR and how they 
contribute to the weight of evidence for an association between health 
effects and exposure to chlorinated surface water.
    While the Stage 1 DBPR was targeted primarily at reducing long-term 
exposures to elevated levels of DBPs to address chronic health risks 
from cancer, the Stage 2 DBPR targets reducing short-term exposures to 
address potential reproductive and developmental health risks and 
cancer risks.
    Based on the weight of evidence from both the human epidemiology 
and animal toxicology data on cancer and reproductive and developmental 
health effects and consideration of the large number of people exposed 
to chlorinated byproducts in drinking water (approximately 254 
million), EPA concludes that: (1) Current reproductive and 
developmental health effects data support a hazard concern, (2) new 
cancer data strengthens the evidence of an association of chlorinated 
water with bladder cancer and suggests an association for colon and 
rectal cancers, and (3) the combined health data warrant regulatory 
action beyond the Stage 1 DBPR.

A. Reproductive and Developmental Epidemiology

    The following section briefly discusses reproductive and 
developmental epidemiology information EPA analyzed, some conclusions 
of these studies and reports, and implications for the Stage 2 DBPR. 
Further discussion of the implications and EPA's conclusions can be 
found in the Stage 2 Economic Analysis (USEPA 2003i).
    EPA has evaluated recently published epidemiological studies 
examining the relationship between exposure to contaminants in 
chlorinated surface water and adverse reproductive and developmental 
outcomes. EPA also considered critical reviews of the epidemiological 
literature by Reif et al. (2000), Bove et al. (2002), and 
Nieuwenhuijsen et al. (2000). Based on these evaluations, EPA believes 
that the reproductive and developmental epidemiology data contribute to 
the weight of evidence on the potential health risks from exposure to 
chlorinated drinking water. Although the data are not suitable for a 
quantitative risk assessment at this time, due in part to 
inconsistencies in the findings, they do suggest that exposure to DBPs 
is a potential reproductive and developmental health hazard.
1. Reif et al. 2000
    Reif et al. (2000) completed a critical review of the epidemiology 
literature pertaining to reproductive and developmental effects of 
exposure to disinfection byproducts in drinking water as a report to 
Health Canada. The review focused on 16 peer-reviewed scientific 
manuscripts and published reports and evaluated associations between 
DBP exposure and outcomes grouped as effects on: (1) Fetal growth--low 
birth weight (<2500g); very low birth weight (<1500g); preterm delivery 
(<37 weeks of gestation) and intrauterine growth retardation (or small 
for gestational age); (2) fetal viability (spontaneous abortion and 
stillbirth) and (3) fetal malformations (all malformations, oral cleft 
defects, major cardiac defects, neural tube defects, and chromosomal 
abnormalities).
    a. Fetal growth. Reif et al. (2000) found inconsistent 
epidemiological evidence for an association between DBPs and fetal 
growth. Some studies found weak but statistically significant 
associations (Gallagher et al. 1998; Bove et al. 1992 and 1995), while 
two studies found no association (Dodds et al. 1999; and Savitz et al. 
1995) with fetal growth.
    b. Fetal viability. Reif et al. 2000's review of the literature 
found inconsistencies in the epidemiological evidence for the 
association between DBP exposure and fetal viability. For instance, the 
study by Waller et al. 1998 found an apparent dose-dependent increase 
in rates of spontaneous

[[Page 49558]]

abortions associated with TTHMs in California. On the other hand, 
Savitz et al. (1995) found little evidence of an association using 
either the concentration of TTHM =81 [mu]g/L or a dose 
estimate based on the amount of tap water consumed. An increased risk 
of stillbirth was reported for women in Nova Scotia by Dodds et al. 
1999, but in New Jersey, Bove et al. (1992, 1995) found little evidence 
of an association with TTHM at 80 [mu]g/L, but did report a weak 
association between stillbirth and use of surface water systems. 
Aschengrau et al. (1993) found an association between stillbirth and 
the use of a chlorinated vs. chloraminated surface water supply, but 
not for exposure to surface water.
    c. Fetal malformations and other developmental anomalies. Reif et 
al. (2000) considered the data for congenital anomalies to be 
inconsistent across the six studies that have explored these outcomes. 
For example, two of the four studies on neural tube defects (Bove et 
al. 1995; Magnus et al. 1999) reported significant excess risks, but 
the remaining two studies (Dodds et al. 1999; Klotz and Pyrch et al. 
1999) did not. These studies found lower risks or no evidence of an 
association with TTHM. However, those studies were conducted in 
locations with either very low or high concentrations of DBPs which may 
have limited the contrast in exposures, thereby reducing the ability to 
detect increased risks. An assessment of congenital anomalies is also 
difficult due to the relatively small number of cases available for 
evaluation.
    Overall, Reif et al. (2000) conclude that the weight of evidence 
from the epidemiological studies suggest that ``DBPs are likely to be 
reproductive toxicants in humans under appropriate exposure 
conditions.'' Reif et al. comment that data from animal studies of 
individual DBPs provide biological plausibility for the effects 
observed in epidemiological studies. Although the authors recognize 
that the ``data are primarily at the stage of hazard identification,'' 
they conclude that ``measures aimed at reducing the concentrations of 
byproducts could have a positive impact on public health.''
2. Bove et al. 2002
    Bove et al. (2002) conducted a qualitative review of 14 
epidemiological studies that evaluated possible developmental and 
reproductive endpoints associated with exposure to chlorination 
byproducts in drinking water. Similar to Reif et al., Bove et al. 
evaluated associations between DBP exposure and outcomes grouped as 
effects on (1) fetal growth--small for gestational age (SGA) as defined 
in each study (usually defined as the fifth or tenth percentile weight 
by gestational week of birth); (2) fetal viability--spontaneous 
abortion and stillbirth; and (3) fetal malformations (neural tube 
defects, oral clefts, and cardiac defects).
    a. Fetal growth. Bove et al. found that, although the studies that 
evaluated SGA had several limitations, three studies out of eight 
(Kramer et al. 1992, Bove et al. 1995, and Gallagher et al. 1998) 
``provided moderate evidence for a causal relationship between a narrow 
definition of SGA * * * and TTHM levels that could be found currently 
in some U.S. public water systems.'' They also concluded that the study 
with the best exposure assessment found the strongest association 
between SGA and TTHM exposure (Gallagher et al. 1998). One study found 
a very weak association (Dodds et al. 1999) and the other four did not 
observe an association (Yang et al. 2000, Kanitz et al. 1996, Kallen et 
al. 2000, and Jaakkola et al. 2001).
    b. Fetal viability. Bove et al. evaluated three studies on 
spontaneous abortion and three studies on stillbirth. Again, Bove et 
al. found that the study employing the best methods found the strongest 
association between TTHM exposure and spontaneous abortions (Waller et 
al. 1998). The other two studies (Savitz et al. 1995 and Aschengrau et 
al. 1989) found weak associations. Two of the studies investigating 
stillbirths found an association between stillbirths and chlorinated 
surface water (Dodds et al. 2001 and Aschengrau et al. 1993). The third 
study (Bove et al. 1995) found no association, however this study did 
not evaluate individual THM levels or cause of death information.
    c. Fetal malformations. Bove et al. evaluated seven studies that 
investigated the relationship between birth defects and DBP exposure. 
This evaluation found ``consistency among these studies in the findings 
for neural tube defects and oral cleft defects, but not for cardiac 
defects. Associations were found for neural tube defects in all three 
studies that examined neural tube defects. These studies also evaluated 
levels of THM exposure (Bove et al. 1995; Dodds et al. 1999; Klotz et 
al. 1999).'' Two studies evaluated oral cleft defects and levels of 
THMs; one found an association with TTHM (Bove et al. 1995) and the 
other found an association with chloroform (Dodds et al. 2001). A third 
study that did not evaluate THM levels did not identify an association 
with oral cleft defects (Jaakkola et al. 2001). Bove et al. 1995 found 
an association between cardiac defects and TTHM, but Dodds et al. 1999, 
2001 and Shaw et al. 1991 did not. An association between chlorination 
and urinary tract defects was found in the three studies that evaluated 
that endpoint (K[auml]ll[eacute]n et al. 2000; Magnus et al. 1999; 
Aschengrau et al. 1993).
    Bove et al. (2002) concluded that the current reproductive and 
developmental epidemiological database for exposure to chlorinated 
byproducts in drinking water presents moderate evidence for 
associations between DBP exposure and SGA, neural tube defects and 
spontaneous abortion. The authors acknowledged the difficulties in 
assessing exposure with any precision in the studies reviewed, but held 
the opinion that misclassification of exposure would tend to 
underestimate rather than overestimate the risk.
3. Nieuwenhuijsen et al. 2000
    Nieuwenhuijsen et al. (2000) reviewed the toxicological and 
epidemiological literature and evaluated the potential risk of 
chlorination DBPs on human reproductive health. The authors state that 
``some studies have shown associations for DBPs and other outcomes such 
as spontaneous abortions, stillbirths and birth defects, and although 
the evidence for these associations is weaker it is gaining weight.'' 
Nieuwenhuijsen et al. also concluded that, ``although studies report 
small risks that are difficult to interpret, the large number of people 
exposed to chlorinated water supplies constitutes a public health 
concern.''
4. Additional Epidemiology Studies
    Three new reproductive and developmental epidemiological studies 
were completed that were not included in the Reif et al. 2000, Bove et 
al. 2002, or Nieuwenhuijsen et al. 2000 literature reviews.
    Waller et al. 2001, recalculated the total trihalomethane exposures 
from their original publication (Waller et al. 1998) to evaluate two 
exposure assessment methods (closest site and utility-wide average). 
The new calculations were intended to reduce exposure misclassification 
by employing weighting factors and subset analyses. As in the 1998 
publication, the new methods found a relationship between spontaneous 
abortion and THM exposure, although the unweighted utility-wide point 
estimate was lower than reported in the original manuscript.
    Hwang et al. 2002, assessed the effect of water chlorination 
byproducts on specific birth defects in Norway by

[[Page 49559]]

classifying exposure on the basis of chlorination (yes/no) and amount 
of natural organic matter in the water. Statistically significant 
associations with exposure were found for risks of any birth defect, 
cardiac, respiratory, and urinary tract defects. For specific birth 
defects, a statistically significant association was found for a defect 
of the septum in the heart.
    Windham et al., 2003, assessed the relationship between exposure to 
THMs in drinking water and characteristics of the menstrual cycle among 
403 women who provided daily urine samples for an average of 5.6 
cycles. Women whose tap water had TTHM levels more than 0.060 mg/l had 
statistically significantly shorter menstrual cycles than women whose 
tap water had lower TTHMs. On average, the menstrual cycles of women 
with the higher levels of TTHMs were one day shorter than cycles of 
women with the lower levels (adjusted difference: -1.1 days, 95% 
confidence interval: -1.8 days to -0.4 days). This shortening occurred 
during the first half of the cycle, before ovulation (adjusted 
difference: -0.9 days; 95% confidence interval: -1.6 days to -0.2 
days). There were no changes in bleed length or in the regularity of 
the cycles. Based on their study, Windham et al., 2003, suggested that 
THM exposure may affect ovarian function, but since this is the first 
study to examine human menstrual cycle variation in relation to THM 
exposure, more research is needed to confirm the relationship. The 
public health implication of a small reduction in menstrual cycle 
length is not clear, but if THMs are related to disturbances in ovarian 
function, that might provide insight into the observed associations 
between THMs and a variety of adverse reproductive outcomes.
    EPA's epidemiology research program continues to examine the 
relationship between exposure to DBPs and adverse developmental and 
reproductive effects. The Agency is supporting several studies using 
improved study designs to provide better information for characterizing 
potential risks. Details on EPA's epidemiology research program can be 
found at http://cfint.rtpnc.epa.gov/dwportal/cfm/dwMDBP.cfm.

B. Reproductive and Developmental Toxicology

    Several new reproductive and developmental toxicology studies have 
become available since the December 1998 Stage 1 DBPR. This discussion 
presents some conclusions derived from these studies and reports, 
including hazard identification, as well as implications for the Stage 
2 DBPR.
    EPA conducted a literature search of animal toxicology studies on 
chronic and subchronic DBP exposures associated with reproductive and 
developmental health effects, evaluated the current reproductive and 
developmental toxicological database for several individual DBPs, and 
assessed two independent reviews (Tyl 2000 and WHO 2000). As a result 
of these analyses, EPA has concluded that although the database is not 
strong enough to quantify risk, it is sufficient to support a hazard 
concern. This hazard concern supports the need to address potential 
reproductive and developmental health effects in the Stage 2 DBPR. The 
following section describes how this conclusion was reached.
1. EPA Analysis and Research
    Since the Stage 1 DBPR, EPA has continued to support reproductive 
and developmental toxicological research on various disinfection 
byproducts through extramural and intramural research programs. 
Information on EPA's toxicology programs can be found at http://www.epa.gov/nheerl/. These studies, along with data on several DBPs 
published after the 1998 Stage 1 DBPR, are summarized in the updated 
children's health document, ``Health Risks to Fetuses, Infants, and 
Children: A Review'' (USEPA 2003a).
    In addition to this compilation of data, EPA has also prepared 
individual health criteria documents that provide detailed summaries of 
the relevant new information, as well as an overall characterization of 
the human health risks from exposure to certain DBPs (USEPA 2003b-USEPA 
2003h, USEPA 2003l). From these new evaluations, EPA has concluded that 
several new studies on individual byproducts contribute to the weight 
of evidence for an association between DBP exposure and adverse effects 
on the developing fetus and reproduction. These effects include fetal 
loss, cardiovascular effects, and male reproductive effects and are 
associated with bromodichloromethane (BDCM), dichloroacetic acid 
(DCAA), trichloroacetic acid (TCAA), bromochloroacetic acid (BCAA), and 
dibromoacetic acid (DBAA). The data from these new studies do not 
change the MCLGs that were established as a part of the Stage 1 DBPR.
2. Tyl 2000
    Tyl (2000) conducted a comprehensive review of the reproductive and 
developmental toxicology literature on DBPs representing over thirty-
five studies. Adverse effects reported by these studies include 
developmental effects, whole litter resorption, reduced fetal body 
weights, and male reproductive effects (e.g., inhibited spermiation, 
increased abnormal sperm). Many of these studies are categorized as 
high-dose, short-term screening studies that can be used to assess 
potential hazard (Table III-1), while the long term, two-generation 
reproduction studies could be an appropriate basis for quantitative 
risk assessment.

----------------------------------------------------------------------------------------------------------------
                                                            Developmental
            Disinfectant/DBP               Screening \1\         \2\           Two-generation \3\ reproductive
----------------------------------------------------------------------------------------------------------------
Chlorine................................  ...............        [bcheck]   ....................................
Chlorine Dioxide........................        [bcheck]         [bcheck]   ....................................
Chloramine..............................  ...............        [bcheck]   ....................................
Chloroform..............................        [bcheck]         [bcheck]   [bcheck]
Bromoform...............................        [bcheck]         [bcheck]   [bcheck]
Bromodichloromethane....................        [bcheck]         [bcheck]   in progress
Dibromochloromethane....................        [bcheck]         [bcheck]   ....................................
Monochloroacetic acid...................        [bcheck]         [bcheck]   ....................................
Dichloroacetic acid.....................        [bcheck]         [bcheck]   ....................................
Trichloroacetic acid....................        [bcheck]         [bcheck]   ....................................
Monobromoacetic acid....................        [bcheck]         [bcheck]   ....................................
Dibromoacetic acid......................        [bcheck]         [bcheck]   in progress
Tribromoacetic acid.....................        [bcheck]   ...............  ....................................
Bromochloroacetic acid..................        [bcheck]   ...............  in planning stage
Bromodichloroacetic acid................        [bcheck]   ...............  ....................................
Dibromochloroacetic acid................        [bcheck]   ...............  ....................................

[[Page 49560]]

 
Chloroacetonitrile......................        [bcheck]   ...............  ....................................
Dichloroacetonitrile....................        [bcheck]         [bcheck]   ....................................
Trichloroacetonitrile...................        [bcheck]         [bcheck]   ....................................
Bromoacetonitrile.......................        [bcheck]         [bcheck]   ....................................
Dibromoacetonitrile.....................        [bcheck]   ...............  ....................................
Tribromoacetonitrile....................  ...............  ...............  ....................................
Bromochloroacetonitrile.................        [bcheck]         [bcheck]   ....................................
Propanal................................        [bcheck]         [bcheck]   ....................................
1,1 Dichloropropanone...................        [bcheck]   ...............  ....................................
Hexachloropropanone.....................        [bcheck]   ...............  ....................................
Dichloromethane.........................        [bcheck]   ...............  ....................................
MX......................................        [bcheck]         [bcheck]   ....................................
Bromate.................................        [bcheck]   ...............  ....................................
Chlorite................................        [bcheck]         [bcheck]   [bcheck]
----------------------------------------------------------------------------------------------------------------
[bcheck] denotes the availability of at least one study in the following categories.
\1\ Screening studies are for hazard identification. These types of studies include the following: whole embryo
  culture, NTP 35-day screening studies, Chernoff-Kavlock and its modified version, and short-term male
  reproductive toxicity screen.
\2\ Developmental studies are used for dose-response determinations.
\3\ Two-generation reproductive studies are multi-generation reproductive toxicity studies used for dose-
  response determinations.

    Tyl concluded that, ``The screening studies, performed for a number 
of DBPs, are `adequate' and `sufficient' only to detect potent 
reproductive/developmental toxicants for hazard identification.'' Tyl 
further confirms that the database identifies certain DBPs with 
potential reproductive or developmental effects (Table III-2) and these 
are discussed further in the next section.

      Table III-2.--Potential Hazards of DBPs for Reproductive and
             Developmental Effects (Adapted From Tyl, 2000)
------------------------------------------------------------------------
             Type of hazard                  Disinfection byproducts
------------------------------------------------------------------------
Developmental defects..................  TCAA, DCAA, MCAA and chlorite.
Whole litter resorption................  Chloroform, bromoform, BDCM,
                                          DBCM, DCAA, TCAA, DCAN, and
                                          TCAN.
Fetotoxicity (reduced fetal body         Chloroform, BDCM, DBCM, DCAA,
 weights, increased variations).          TCAA, DCAN, TCAN, DBAN, BCAN,
                                          MCAN.
Male reproductive effects                DCAA, DBAA, BDCM.
 (spermatotoxic).
------------------------------------------------------------------------

    a. Developmental defects. Tyl noted that adverse developmental 
effects that were reported from whole embryo culture tests on the 
developing heart, neural tube, eye, pharyngeal arch, and somites tended 
to be associated with haloacetic acids tested at high doses (Hunter et 
al. 1996; Saillenfait et al. 1995, Smith et al. 1989). Cardiovascular 
effects were also observed in vivo for TCAA and DCAA from developmental 
segment II toxicity studies at high doses (Smith et al. 1988, 1990).
    b. Whole litter resorption. Whole litter resorption, likened to 
miscarriage or spontaneous abortion by Tyl 2000, was also observed at 
high doses in vivo for a range of DBPs as indicated in Table III-2 
(Murray et al. 1979, Balster and Borzellca, 1982, Narotsky et al. 1992; 
1997 a, b; Bielmeier et al. 2001; Smith et al. 1990; Smith et al. 
1988). Tyl noted that similar effects were observed in several 
epidemiology studies.
    c. Fetal toxicity. Fetal toxic effects such as reduced fetal body 
weights and increased variation were observed at high doses in vivo for 
a range of DBPs (e.g., chloroform, BDCM, DBCM, DCAA, TCAA, DCAN, TCAN, 
DBAN, BCAN) (Thompson et al. 1974; Schwetz et al. 1974; Murray et al. 
1979; Ruddick et al. 1983; Narotsky et al. 1992, Balster and 
Borzelleca, 1982; Smith et al. 1990). Again, Tyl noted a similarity in 
effects observed in epidemiology studies.
    d. Male reproductive effects. Animal toxicology studies report 
increased risks of adverse effects on the male reproductive system from 
high doses of haloacetic acids and other DBPs that have not been 
studied in human epidemiology studies. Male reproductive effects (e.g., 
inhibited spermiation, reduced epididymus, sperm number and motility, 
increased abnormal sperm, testicular damage and inhibited in vitro 
fertilization) were reported for DCAA, DBAA, TCAA and BDCM (Toth et al. 
1992, Linder et al. 1997a, b; Linder et al. 1994a, b; Cosby and Dukelow 
1992). Dr. Tyl noted that the adverse effects observed in the male 
reproductive toxicity screening studies (Toth et al. 1992; Linder et 
al. 1994a, b; 1997a, b) are confounded by a short dosing regimen and 
administration of test doses to only adult males.
    From her review of the comprehensive animal toxicology database on 
reproductive and developmental health effects from DBP exposure, Dr. 
Tyl concludes that ``some DBPs have an intrinsic capacity to do harm, 
specifically to the developing conceptus and the male (and possibly the 
female) reproductive system''. She concludes that ``there is hazard to 
development from the haloacetic acids (TCAA, DCAA, MCAA) and acetate; 
to development from chloroform, bromoform, BDCM, DBCM, DCAA, TCAA, 
DCAN, and TCAN expressed as full litter resorption (which most likely 
indicates maternal endocrine/uterine effects); and fetotoxicity for 
chloroform, BDCM, DBCM, DCAA, TCAA, DCAN, TCAN, DBAN, BCAN, CAN, 
acetaldehyde, and possibly formaldehyde. Reproductive hazard exists for 
DCAA, DBAA, and possibly formaldehyde in males and for TCE and possibly 
formaldehyde in females.''

[[Page 49561]]

3. World Health Organization Review of the Reproductive and 
Developmental Toxicology Literature (2000)
    The International Programme on Chemical Safety (IPCS) published an 
evaluation of Disinfectants and DBPs in its Environmental Health 
Criteria monograph series (WHO 2000). In this review of the toxicology 
data on reproductive and developmental effects from DBP exposure, the 
World Health Organization (WHO) concludes that although the data on 
these effects are not as robust as the cancer database, these effects 
are of potential health concern. The WHO concludes that reproductive 
effects in females have been principally embryolethality and fetal 
resorptions associated with the haloacetonitriles 
(trichloroacetonitrile, dichloroacetonitrile, bromochloroacetonitrile, 
and dibromoacetonitrile) and the dihaloacetates, while DCAA and DBAA 
have both been associated with adverse effects on male reproduction.
4. New Studies
    Christian et al. (2001) conducted a developmental toxicity study 
with pregnant New Zealand White rabbits exposed to BDCM in drinking 
water at concentrations of 0, 15, 150, 450, and 900 ppm in drinking 
water on gestation days 6-29. The no observed adverse effect level 
(NOAEL) and lowest observed adverse effect level (LOAEL) identified for 
maternal toxicity in this study were 13.4 mg/kg-day (150 ppm) and 35.6 
mg/kg-day (450 ppm), respectively, based on decreased body weight gain. 
The developmental NOAEL was 55.3 mg/kg-day (900 ppm) based on absence 
of statistically significant, dose-related effects at any tested 
concentration. Christian et al. (2001) also conducted a developmental 
study of BDCM in a second species, Sprague-Dawley rats. Rats were 
exposed to BDCM in the drinking water at concentrations of 0, 50, 150, 
450, and 900 ppm on gestation days 6 to 21. The concentration-based 
maternal NOAEL and LOAEL for this study were 150 ppm and 450 ppm, 
respectively, based on statistically significant, persistent reductions 
in maternal body weight and body weight gains. Based on the mean 
consumed dosage of bromodichloromethane, these concentrations 
correspond to doses of 18.4 mg/kg-day and 45.0 mg/kg-day, respectively. 
The concentration-based developmental NOAEL and LOAEL were 450 ppm and 
900 ppm, respectively, based on a significantly decreased number of 
ossification sites per fetus for the forelimb phalanges (bones of the 
hand or the foot) and the hindlimb metatarsals and phalanges. These 
concentrations correspond to mean consumed doses of 45.0 mg/kg-day and 
82.0 mg/kg-day, respectively.
    Christian et al. (2002b) summarized the results of a two-generation 
reproductive toxicity study on bromodichloromethane conducted in 
Sprague-Dawley rats. Bromodichloromethane was continuously provided to 
test animals in the drinking water at concentrations of 0, 50, 150, or 
450 ppm. Average daily doses estimated for the 50, 150, and 450 ppm 
concentrations were reportedly 4.1 to 12.6, 11.6 to 40.2, and 29.5 to 
109 mg/kg-day, respectively. The parental NOAEL and LOAEL were 50 and 
150 ppm, respectively, based on statistically significant reduced body 
weight and body weight gain; F1 and F2 generation pup body weights were 
reduced in the 150 and 450 ppm groups during the lactation period after 
the pups began to drink the water provided to the dams. Body weight and 
body weight gain were also reduced in the 150 and 450 ppm F1 generation 
males and females. A marginal effect on estrous cyclicity was observed 
in F1 females in the 450 ppm exposure group. Small (<=6%), but 
statistically significant, delays in F1 generation sexual maturation 
occurred at 150 (males) and 450 ppm (males and females) as determined 
by timing of vaginal patency or preputial separation. The study's 
authors considered these effects to be a secondary response associated 
with reduced body weight, which appears to be dehydration brought about 
by taste aversion to the compound. The results of this study identify 
NOAEL and LOAEL values for reproductive effects of 50 ppm (4.1 to 12.6 
mg/kg-day) and 150 ppm (11.6 to 40.2 mg/kg-day), respectively, based on 
delayed sexual maturation.
    Bielmeier et al. (2001) conducted a series of experiments to 
investigate the mode of action in bromodichloromethane-induced full 
litter resorption (FLR). The study included a strain comparison of F344 
and Sprague-Dawley (SD) rats. In the strain comparison experiment, 
female SD rats (13 to 14/dose group) were dosed with 0, 75, or 100 mg/
kg-day by aqueous gavage in 10% Emulphor[reg] on GD 6 to 10. F344 rats 
(12 to 14/dose group) were dosed with 0 or 75 mg/kg-day administered in 
the same vehicle. The incidence of FLR in the bromodichloromethane-
treated F344 rats was 62%, while the incidence of FLR in SD rats 
treated with 75 or 100 mg/kg-day of bromodichloromethane was 0%. Both 
strains of rats showed similar signs of maternal toxicity, and the 
percent body weight loss after the first day of dosing was comparable 
for SD rats and the F344 rats that resorbed their litters. The rats 
were allowed to deliver and pups were examined on postnatal days 1 and 
6. Surviving litters appeared normal and no effect on post-natal 
survival, litter size, or pup weight was observed. The series of 
experiments conducted by Bielmeier et al. (2001) identified a LOAEL of 
75 mg/kg-day (the lowest dose tested) based on FLR in F344 rats. A 
NOAEL was not identified. Mechanistic studies indicate that BDCM-
induced pregnancy loss is likely to be luteinizing hormone (LH)-
mediated (Bielmeier et al., 2001). It is possible that BDCM alters LH 
levels by disrupting the hypothalamic-pituitary-gonadal axis or by 
altering the responsiveness of the corpora lutea to LH. Since these 
possible mechanisms are potentially relevant to pregnancy maintenance 
in humans, EPA believes the finding of BDCM-induced pregnancy loss in 
F344 rats is relevant to risk assessment, and may provide insight into 
the epidemiological finding of increased risk of spontaneous abortion 
associated with consumption of BDCM (Waller et al. 1998, 2001).
    Christian et al. (2002a) recently completed a two-generation 
drinking water study of DBA in rats. Male and female Sprague-Dawley 
rats (30/sex/exposure group) were administered DBA in drinking water at 
concentrations of 0, 50, 250, or 650 ppm continuously from initiation 
of exposure of the parental (P) generation male and female rats through 
weaning of the F2 offspring. Based on testicular 
histomorphology indicative of abnormal spermatogenesis in P and 
F1 males, the parental and reproductive/developmental 
toxicity LOAEL and NOAEL are 250 and 50 ppm, respectively.
    Previous studies by EPA have reported adverse effects of DBA, 
administered via oral gavage, on spermatogenesis that impacted male 
fertility (Linder et al. 1994a, 1995, 1997a) at doses-comparable to 
those achieved in the Christian et al. (2002a) study. Based on these 
studies collectively, it is clear that DBA is spermatotoxic. Moreover, 
Veeramachaneni et al. (2000) reported in an abstract that sperm from 
male rabbits exposed to DBA in utero from gestation days 15 and 
throughout life reduced the fertility of artificially inseminated 
females as evidenced by reduced conceptions. When published, this study 
may support the evidence that DBA is a male reproductive system 
toxicant .
    In addition, research on DBA by Klinefelter et al. (2001) has

[[Page 49562]]

demonstrated statistically significant delays in both vaginal opening 
and preputial separation using the body weight on the day of 
acquisition (postnatal day 45) as the co-variant. This was not found by 
Christian et al (2002a) using the body weight at weaning as the 
statistical covariant. However, the authors analyzed the data for 
preputial separation and vaginal opening with body weight on the day of 
weaning as a co-variant rather than body weight on the day of 
acquisition, i.e., the day that the prepuce separates or the day the 
vagina opens. It is likely that there was an increase in body weight 
from postnatal day 21 (weaning) until preputial separation (day 45) 
that was independent of the delay in sexual maturation.
    Although the Christian et al. (2002a) study was conducted in 
accordance with EPA's 1998 testing guidelines, EPA has incorporated 
newer, more sophisticated measures into recent intramural and 
extramural studies that have not yet been incorporated into the testing 
guidelines. Such measures include measuring changes in specific 
proteins in the sperm membrane proteome and fertility assessments via 
in utero insemination. EPA believes that additional research is needed, 
utilizing these newer toxicological measures, to clarify the extent to 
which DBA poses human reproductive or developmental risk. The database 
on male reproductive effects from exposure to DBA is incomplete and is 
not suitable for quantitative risk assessment at this time. It does, 
however, identify reproductive effects as an area of concern.

C. Conclusions Drawn From the Reproductive and Developmental Health 
Effects Data

    EPA believes that the weight of evidence of the best available 
science, in conjunction with the widespread exposure, supports 
regulatory changes that target peak DBP exposures specifically through 
the Stage 2 DBPR. Several epidemiology studies found statistically 
significant associations between exposure to chlorinated drinking water 
and fetal growth, spontaneous abortion, stillbirth, and neural tube 
defects. Although uncertainties remain and the current database does 
not support a quantitative reproductive and developmental risk 
assessment for most of the DBPs, the weight of evidence provides an 
indication of a hazard concern that warrants additional regulatory 
action beyond the Stage 1 DBPR.
    Biological plausibility for the effects observed in epidemiological 
studies has been demonstrated through various toxicological studies. 
Tyl 2000 states that ``effects observed in animal studies included 
embryonic heart and neural tube defects from haloacetic acids in vitro 
and in vivo, and full litter resorption, reduced numbers of implants 
per litter, and reduced fetal body weight per litter were also observed 
from exposure to specific trihalomethanes. Comparable effects were also 
observed in children in some (but not all) epidemiological studies, 
with exposure to trihalomethanes (THMs) usually used as a surrogate for 
specific DBP classes or individual DBPs, as follows: increased 
incidences of cardiac defects (Bove et al. 1995) and of neural tube 
defects in children (Bove et al. 1995; Dodds et al. 1999; Klotz and 
Pyrch 1998) were reported. Intrauterine growth retardation (IUGR, 
approximately equivalent to reduced fetal body weights per litter) was 
reported to be associated with waterborne chloroform (Kramer et al. 
1992; Bove et al. 1995; Gallagher et al. 1998). Miscarriage or 
spontaneous abortion, or stillbirth (approximately equivalent to whole 
litter resorption, reduced numbers of total and/or live implants per 
litter, and increased resorptions per litter) were observed by Waller 
et al., 1998; Dodds et al., 1999; and Bove et al., 1995.''
    Similarity of effects between animals and humans lends credence to 
and strengthens the weight of evidence for an association between 
adverse reproductive and developmental health effects and exposure to 
chlorinated surface water. EPA believes that the weight of evidence of 
both the reproductive and developmental toxicological and 
epidemiological databases suggests that exposure to DBPs may induce 
potential adverse health effects on reproduction and fetal development 
at some DBP exposures. However, additional toxicological work is 
necessary to identify the mode of action for the effects observed.

D. Cancer Epidemiology

    Epidemiological studies on cancer provide valuable information that 
contributes to the overall evidence on the potential human health 
hazards from exposure to chlorinated drinking water. In the area of 
epidemiology, a number of studies have been conducted to investigate 
the relationship between exposure to chlorinated surface water and 
cancer. While EPA cannot conclude there is a causal link between 
exposure to chlorinated surface water and cancer, some studies have 
found an association between bladder, rectal and colon cancer and 
exposure to chlorinated surface water.
1. Population Attributable Risk Analysis
    Some epidemiological studies have linked the consumption of 
chlorinated surface waters to an increased risk of two major causes of 
human mortality in the United States, colorectal and bladder cancers 
(Cantor 1998). Bladder cancer was chosen as the primary endpoint of 
concern in the Stage 1 DBPR (USEPA 1998f) economic analysis because it 
had the most consistent database for a possible association to 
chlorinated surface water exposure. More studies have considered 
bladder cancer than any other cancer. EPA used the published mean risk 
estimates from five studies to quantify the potential range of risk for 
bladder cancer from DBP exposure. These risks were expressed as a range 
of population attributable risks (PAR) of 2-17% (USEPA 1998f). This 
means that if the associations reported in the studies turn out to 
reflect a causal link, between 2 and 17% of new bladder cancer cases 
could be attributable to DBPs. This PAR range also represents that 
portion of the bladder cancer cases that would not have occurred if the 
exposure to chlorinated drinking water were absent. A complete 
discussion of the Stage 1 DBPR bladder cancer PAR evaluation, including 
uncertainties and assumptions, can be found in the Stage 2 DBPR 
Economic Analysis (USEPA 2003i).
    While EPA recognized the limitations of the epidemiological 
database for making risk estimates, the Agency believed that it was 
useful for developing an estimate of bladder cancer risk. The PARs were 
derived from measured risks (Odds Ratios and Relative Risk) based on 
the number of years exposed to chlorinated surface water. The 
uncertainties associated with these PAR estimates are largely due to 
the common prevalence of both the disease (bladder cancer) and exposure 
(chlorinated drinking water). EPA recognizes that risks from 
chlorinated drinking water may be lower or higher than those estimated 
from the epidemiological literature, and that the PAR range could 
include zero or be higher than 17%.
    Using the PARs of 2% and 17%, EPA estimated that the number of 
possible bladder cancer cases per year potentially associated with 
exposures to DBPs in chlorinated drinking water could range from 1,100 
to 9,300 cases. This was based on the estimate of 54,500 new bladder 
cancer cases per year nationally, as projected by the National Cancer 
Institute for 1997. A thorough discussion of cancer studies published 
prior to 1998 and possible

[[Page 49563]]

associations with DBP exposure can be found in the Stage 1 DBPR (USEPA 
1998c).
2. New Epidemiological Cancer Studies
    New studies published since the Stage 1 DBPR continue to support an 
association between bladder, colon and rectal cancers and exposure to 
chlorinated surface water (Yang et al. 1998; Koivusalo et al. 1998; 
King et al. 2000b). Based on the weight of evidence provided by the 
cancer epidemiology database, EPA has chosen to use the same PAR 
analysis to estimate the primary benefits from bladder cancer cases 
potentially avoided as a consequence of reducing the DBP levels from 
the Stage 2 DBPR (see section VII). For the Stage 2 DBPR analysis, EPA 
updated the 1997 estimate of new bladder cancer cases per year 
nationally from 54,500 to 56,500 (projected by the American Cancer 
Society, 2002) and accounted for the reductions in DBP exposure that 
were projected for the Stage 1 DBPR.
    a. New bladder cancer studies. Bladder cancer and chlorinated DBP 
exposure has historically been the most strongly supported association 
of all the possible cancers, based on human evidence. Two new studies 
(Yang et al. 1998 and Koivusalo et al. 1998) also suggest an 
association of DBP exposure with bladder cancer. Yang et al. 1998 found 
a positive association between consumption of chlorinated drinking 
water and bladder cancer. Koivusalo et al. (1998) found evidence of 
increased risk as a function of increasing DBP exposure duration. Long 
exposure durations (=45 years for Koivusalo et al. 1998) 
were associated with about a two-fold increase in risk. The new bladder 
cancer studies continue to support an association and potential for a 
causal relationship between exposure to chlorination byproducts and 
risk for bladder cancer.
    A new publication by C.M. Villanueva et al. (Villanueva et al. 
2003) reports on their meta-analysis of case-control and cohort 
studies. This meta-analysis may be useful for improving the estimate of 
national population attributable risk (fraction of bladder cancer cases 
in the U.S. that may be attributed to chlorinated drinking water). 
Compared to EPA's current approach (i.e., providing a range of 
population attributable risks (PAR)), use of the meta-estimate would 
provide a more stable result because:
    [sbull] It provides a single (meta) estimate of the odds ratio from 
which to calculate the PAR, thereby summarizing the results across 
studies, thus reducing the influence of geographic and temporal 
differences.
    [sbull] It uses three additional high-quality studies not included 
in the PAR range analysis conducted by EPA (i.e., studies by Koivusalo 
et al. 1998, Doyle et al. 1997, and Vena et al. 1993).
    [sbull] It weights the individual studies according to their 
precision, so more precise estimates (due principally to greater 
numbers of cases) carry greater statistical weight and therefore have 
greater influence on the meta-estimate.
    [sbull] In addition to the primary analysis, the authors conducted 
an evaluation of the robustness of their conclusions. They examined the 
sensitivity of estimates to decisions made with respect to exposure 
definitions, cut points defining exposure groups, inclusion/exclusion 
of individual studies, and potential publication bias.
    The meta-analysis provided at least two meta-estimates that may be 
useful for estimating national population attributable risk:
    [sbull] A combined odds ratio for ever-exposure, with confidence 
intervals and
    [sbull] A combined dose-response regression slope coefficient, 
relating increasing odds ratios to additional years of chlorinated 
drinking water consumption.
    EPA conducted an estimate of the impact of using the meta-analysis 
to provide a perspective on the national population attributable risk. 
This estimate is based on the author's correction of a minor 
transcription error in their published manuscript (the appropriate 
estimate for the King study yields corrected over-all odds ratio for 
ever-consumers of 1.2 with 95% confidence interval of 1.091 to 1.320, 
personal communication from M. Kogevinas to M. Messner, 5/19/2003). 
Assuming 70% of the U.S. population is in the ever-consumed category 
(based on the chlorinated surface water exposed population), a point 
estimate of the population attributable risk using the odds ratio from 
the meta-analysis is 12% (95% interval 6% to 18%). Although EPA's 
population attributable risk range (2% to 17%) was not intended to 
convey a quantified level of confidence, it is not vastly different 
from the meta-analysis' 95% confidence range of 6% to 18%. EPA regards 
the meta-range as additional support for EPA's population attributable 
risk range. The meta-analysis provides continued support for an 
association between exposure to chlorinated surface water and bladder 
cancer.
    EPA requests comment on the use of a meta-estimated odds ratios to 
estimate national population attributable risk for the purpose of 
supporting the benefit analysis for this rule, either based 
specifically on the Villanueva et al. publication or on the application 
of a similar approach. EPA also solicits comments and suggestions for 
use of the combined dose-response regression slope coefficient 
associated with the increased risk of bladder cancer for each 
additional year's exposure to DBPs in drinking water for estimating the 
drop in risk associated with a reduction in DBPs as part of the benefit 
analysis of this rule. EPA provides further discussion and solicitation 
of comment on how the slope factor might further be considered in 
estimating the benefits of this rule in the economic section of this 
preamble.
    b. New colon cancer studies. Colorectal cancer is the third most 
common type of new cancer cases and deaths in both men and women in the 
U.S. It is estimated that 148,300 new colorectal cancer cases will be 
diagnosed in 2002, with 56,600 resulting in deaths (American Cancer 
Society, 2002). Human epidemiology studies on chlorinated surface water 
have reported associations with colorectal cancer. Since the Stage 1 
DBPR, two new human epidemiology studies (Yang et al. 1998 and King et 
al. 2000b) have been conducted to investigate the relationship between 
colon cancer and exposure to chlorinated surface water. Yang et al. 
1998 did not identify an association between consumption of chlorinated 
drinking water and colon cancer. The King et al. (2000b) study found 
evidence of a DBP association with colon cancer among males, but no 
association was observed among females.
    Similarity of effects reported in animal toxicity and human 
epidemiology studies strengthen the weight of evidence for an 
association between DBP exposure and colon cancer. Effects observed in 
animal studies which included tumors in BDCM exposed rats and mice at 
several sites (NTP 1987); colon tumors in bromoform exposed rats (NTP 
1989); and development of aberrant crypt foci, a preneoplastic lesion 
of colon cancer in animals exposed to DBP mixtures (DeAngelo et al. 
2002), are comparable to observations in some cancer epidemiological 
studies showing an association with colorectal cancer and consumption 
of chlorinated water (King et al. 2000b).
    Even with the additional study showing an association, the 
epidemiological database on colon cancer as a whole is not as strong as 
that for bladder cancer. However, this new study increases the weight 
of evidence of an association between DBP exposure

[[Page 49564]]

and colon cancer. The Stage 1 DBPR (USEPA 1998c) includes additional 
discussion of colon cancer risks associated with DBP exposure.
    c. New rectal cancer studies. The evidence for an association 
between DBPs and rectal cancer is stronger than for colon cancer. Yang 
et al. (1998) and Hildesheim et al. (1998) both found associations 
between chlorinated drinking water exposure and rectal cancer, and the 
associations had a similar magnitude in both sexes. Hildesheim et al. 
also found an association in both sexes with lifetime average THM 
concentration. The consistency of the dose-response trends, the 
consistency between sexes, and the apparent control of important 
potential confounders in this study all support the observed 
associations.
    d. Other cancers. Two new human epidemiology studies support the 
possibility of an association between DBPs and kidney cancer. Yang et 
al. (1998) found a positive association for both males and females 
between consumption of chlorinated drinking water and kidney cancer. 
Koivusalo et al. (1998) found a small, statistically significant, 
exposure-related excess risk for kidney cancer for males. The 
association for females was not significant in the Koivusalo et al. 
1998 study. The current database for this endpoint of cancer, however, 
is insufficient to conclude an association.
    Cantor et al. (1999) studied brain cancer, focusing on gliomas. 
None of the exposure variables were related to brain cancer among 
females, but males showed a statistically significant, monotonically 
increasing risk associated with duration of exposure to chlorinated 
surface water. This study suggests a possible association between 
chlorination byproducts and gliomas; however, the evidence from this 
study is not strong enough to support a conclusion of a causal 
association.
    Infante-Rivard et al. (2001) conducted a population-based case-
control study in Quebec Province, Canada, to examine possible 
associations between childhood acute lymphoblastic leukemia and THMs. 
There were no associations with leukemia for any of the exposure 
indices for total THM, or specific THMs. Therefore, the study does not 
provide evidence of an association between any of the exposure 
variables and childhood leukemia.
3. Review of the Cancer Epidemiology Literature (WHO 2000)
    The International Programme on Chemical Safety (IPCS) report on 
disinfectants and disinfection byproducts (WHO 2000) concludes that 
results of analytical epidemiological cancer studies are insufficient 
to support a causal relationship for bladder, colon, rectal, or any 
other cancer and chlorinated drinking water or THMs. The report notes 
that there is better evidence for an association between exposure to 
chlorinated surface water and bladder cancer than for other types of 
cancer. The WHO also concludes that based on the large number of people 
exposed to chlorinated drinking water, there is a need to address this 
potential health concern.

E. Cancer and Other Toxicology

    Few new cancer toxicology studies have been completed since the 
Stage 1 DBPR was finalized in December 1998. The information provided 
in the following sections adds to the toxicology database and provides 
additional support for the Stage 2 DBPR to control DBP peaks (e.g, high 
TTHM and HAA5 levels) throughout distribution systems, but does not 
change the quantitative assessment of the MCLGs.
1. EPA Criteria Documents
    To date, EPA has established lifetime cancer risk levels for four 
DBPs (bromoform, bromodichloromethane, bromate, and dichloroacetic 
acid) classified as ``probable'' carcinogens, as promulgated in the 
Stage 1 DBPR and reported in the Integrated Risk Information System 
(IRIS). Although researchers have continued to assess the cancer risks 
of DBPs, there has been little change in the overall DBP 
carcinogenicity database since the Stage 1 DBPR.
    The most significant new publication since the Stage 1 DBPR was a 
study of DCAA tumorigenicity in mice by DeAngelo et al. (1999). The 
Agency has used the data from this study to revise the slope factor for 
DCAA and a drinking water 10-6 lifetime cancer risk 
concentration. The slope factor is a measure of the potency of a 
carcinogen while the 10-6 lifetime cancer risk concentration 
provides an estimate of the concentration of a contaminant in drinking 
water that is associated with an estimated excess lifetime cancer risk 
of one in a million (Table III-3).
    Another significant advancement beyond the Stage 1 DBPR was the 
evaluation of the chloroform tumorigenicity data on the basis of its 
nonlinear mode of action following the draft 1999 proposed Guidelines 
for Carcinogen Risk Assessment (USEPA 1999a). The new chloroform 
assessment became available on IRIS (2001) in October, 2001 (see 
section V for a more detailed discussion).
    The Criteria Documents for bromoform, bromodichloromethane, 
dibromochloromethane, and dichloroacetic acid that support the Stage 2 
proposal include cancer slope factors and 10-6 lifetime 
cancer risk concentrations that have been modified from their Stage 1 
values in order to reflect the methodology proposed in the 1996/1999 
draft cancer guidelines (USEPA 1999a) (Table III-3). These include the 
values based on the Maximum Likelihood Estimate of the dose producing 
effects in 10 percent of the animals (ED10) and from the 
lower 95 percent confidence bound on that value (LED10). 
Except for dibromochloromethane, which is classified as a possible 
human carcinogen, the DBPs in Table III-3 (and bromate as noted 
previously) are classified as probable human carcinogens.

                                  Table III--3.--Quantification of Cancer Risk
----------------------------------------------------------------------------------------------------------------
                                                      Risk factors from LED10         Risk factors from ED10
----------------------------------------------------------------------------------------------------------------
                                                                     10-6 Risk                       10-6 Risk
             Disinfection byproduct                Slope factor    concentration   Slope factor    concentration
                                                   (mg/kg/day)-1      (mg/L)       (mg/kg/day)-1      (mg/L)
----------------------------------------------------------------------------------------------------------------
Bromodichloromethane............................          0.034           0.001           0.022            0.002
Bromoform.......................................          0.0045          0.008           0.0034           0.01
Dibromochloromethane............................          0.04            0.0009          0.017            0.002
Dichloroacetic Acid.............................          0.048           0.0007          0.014            0.003
----------------------------------------------------------------------------------------------------------------


[[Page 49565]]

    EPA believes that it is important to pursue additional research on 
cancer from DBPs. EPA has several ongoing studies in addition to a 
collaboration with the National Toxicology Program of the National 
Institute of Environmental Health Sciences. More information on EPA's 
toxicology research program can be found at http://www.epa.gov/nheerl.
2. Other Byproducts with Carcinogenic Potential
    a. 3-chloro-4- (dichloromethyl)-5-hydroxy-2(5H) -furanone) (MX)--
multisite cancer. MX is a byproduct of chlorination that is typically 
found at very low concentrations (approximately <0.000067 mg/L) in 
drinking water. The information available on MX was recently compiled 
in the Quantitative Cancer Assessment for MX and chlorohydroxyfuranones 
(USEPA 2000i). Overall, the weight of evidence indicates that MX is a 
direct-acting genotoxicant in mammals, with the ability to induce 
tumors in multiple sites. The primary sites for tumor formation are the 
thyroid and liver.
    b. N-nitrosodimethylamine (NDMA)--multisite cancer. Health effects 
data indicate that NDMA is a probable human carcinogen, as described on 
IRIS (1991). Risk assessments have estimated that the 10-6 
lifetime cancer risk level is 0.000007 mg/L based on induction of 
tumors at multiple sites. Recent studies have produced new information 
on the occurrence and mechanism of formation of NDMA but there is not 
enough information at this time to draw conclusions. More research is 
underway to determine the mechanism by which NDMA is formed in drinking 
water, and the extent of its occurrence in chloraminated systems.
3. Other Toxicological Effects
    The Agency has modified the reference dose (RfD) values for 2 of 
the chlorinated acetic acids since the Stage 1 DBPR. Under the Stage 1 
DBPR there was no established RfD for monochloroacetic acid (MCAA). 
Data from a drinking water exposure study of MCAA in rats by DeAngelo 
et al. (1997) were used to establish an RfD of 0.004 mg/kg/day based on 
observed increases in spleen weight. Data from DeAngelo (1997) were 
also used to calculate a new RfD of 0.03 mg/kg/day for trichloroacetic 
acid (TCAA) based on observed effects on body weight and liver effects. 
Detailed discussions of the new reference doses are located in section 
V of this preamble.
4. WHO Review of the Cancer Toxicology Literature (2000)
    The IPCS report on Disinfectants and Disinfection Byproducts (WHO 
2000) emphasizes that the bulk of the toxicology data focuses primarily 
on carcinogenesis. The Task Group found BDCM to be of particular 
interest because it produces tumors in both rats and mice at several 
sites. Although the HAAs appear to be without significant genotoxic 
activity, the brominated HAAs appear to induce oxidative damage to DNA, 
leading to tumor formation.

F. Conclusions Drawn From the Cancer Epidemiology and Toxicology

    EPA believes that the cancer epidemiology and toxicology databases 
provide important information that contributes to the weight of 
evidence evaluation of the potential health risks from exposure to 
chlorinated drinking water. At this time the cancer epidemiology 
studies are insufficient to establish a causal relationship between 
exposure to chlorinated drinking water and cancer, but EPA does believe 
there is a potential association. The current database is sufficient 
for quantitative analysis on the endpoint of bladder cancer, as 
presented previously in the PAR analysis.
    The association between DBP exposure and colon cancer remains more 
tenuous than the link to bladder cancer, although similarity of effects 
reported in animal toxicity and human epidemiology studies strengthens 
the weight of evidence for an association between DBP exposure and 
colon cancer. Studies finding potential relationships between exposure 
to chlorinated drinking water and rectal, kidney, and brain cancer also 
add to the weight of evidence for a public health concern. EPA believes 
that the overall cancer epidemiology and toxicology data support the 
decision to pursue additional DBP control measures as reflected in the 
Stage 2 DBPR.

G. Request for Comment

    EPA requests comment on the conclusions drawn from the new health 
information summarized in this section. EPA requests comment on the 
weight of evidence evaluation of the potential reproductive and 
developmental hazards from DBPs and its potential implications for the 
regulatory provisions for the final Stage 2 DBPR. EPA solicits any 
additional data on the reproductive or developmental effects from DBPs 
that need to be considered for the final Stage 2 DBPR.
    EPA requests comment on EPA's conclusions regarding cancer 
epidemiology and toxicology, and the new studies discussed in today's 
proposal. EPA solicits any additional cancer epidemiology and 
toxicology data that need to be considered for the final Stage 2 DBPR.
    EPA also solicits any health information available to further 
assess risk to sensitive subpopulations, especially children and the 
elderly.

IV. DBP Occurrence Within Distribution Systems

    New information on the occurrence of DBPs in distribution systems 
raises issues about the protection provided by the Stage 1 DBPR. This 
section presents the new information used to identify key issues and to 
support the development of the Stage 2 DBPR. For a more detailed 
discussion see the Stage 2 Occurrence Assessment for Disinfectants and 
Disinfection Byproducts (USEPA 2003o).
    Under the Stage 1 DBPR, compliance with the DBP MCLs is determined 
by averaging, annually and system-wide, all DBP measurements. The 
following discussion shows that compliance based on system averages of 
DBP concentrations allows a significant number of sampling locations 
within distribution systems to have DBP levels above the MCLs. These 
peak DBP occurrences are masked by averaging with lower distribution 
system occurrence levels. The populations served by portions of the 
distribution system with higher DBP concentrations are not receiving 
the same level of health protection.
    The new information also shows that the highest DBP levels often do 
not occur at distribution system sites identified as representing 
maximum residence time. The information further shows that the highest 
TTHM and HAA5 levels often do not occur at the same site within the 
distribution system. These two findings suggest that it is appropriate 
to reevaluate the Stage 1 DBPR compliance monitoring sites in order to 
target those sites with high DBP levels. EPA believes that distribution 
system compliance monitoring sites need to be reevaluated to ensure 
identification of sites that reflect both high TTHM and HAA5 
occurrence.

A. Data Sources

1. Information Collection Rule Data
    The Information Collection Rule (USEPA 1996a) established 
monitoring and data reporting requirements for large public water 
systems. Under the Information Collection Rule, systems serving at 
least 100,000 people were required to conduct DBP and DBP-

[[Page 49566]]

related monitoring. The 18 months of required monitoring, which began 
in July 1997 and ended in December 1998, applied to 296 public water 
systems (500 treatment plants).
    The Information Collection Rule data show the national occurrence 
of: (1) Influent water quality parameters; (2) primary and secondary 
disinfectant use by the large plants; (3) occurrence of DBPs and DBP 
precursors in treatment plants, finished waters, and distributions 
systems; (4) microbial occurrence (in subpart H systems only); and (5) 
treatment plant monthly operation, and initial as well as final 
treatment plant design. The data were gathered after the Stage 1 DBPR 
was finalized (USEPA 1998c) but well before systems were required to 
meet Stage 1 DBPR requirements.
    The Information Collection Rule required a significant investment 
for the water treatment industry, as well as for the EPA to analyze the 
data. Overall, the occurrence and treatment data collected under the 
Information Collection Rule, excluding microbial data, was estimated to 
cost systems $54 million (USEPA 1996a). In addition, systems using 
source waters with high DBP precursor levels were required to conduct 
bench and pilot studies to evaluate the effectiveness of granular 
activated carbon (GAC) and membrane technology to control for DBPs. The 
estimated cost for these studies totaled approximately $57 million 
(USEPA 1996a).
    In addition to the analysis of DBPs in distribution systems, EPA 
used occurrence data from the Information Collection Rule to confirm 
selection of TTHM and HAA5 as appropriate contaminants for monitoring 
DBPs. EPA also used occurrence data from the Information Collection 
Rule to confirm differences in monitoring requirements for systems 
using surface water versus those using ground water, as stipulated 
under the Stage 1 DBR. Analysis of the Information Collection Rule data 
indicates that TTHM and HAA5 comprise on average, across all systems, 
about 50% of the total mixture of chlorinated DBPs and that TTHM and 
HAA5 concentrations are much lower and less variable in ground water 
systems than in surface water systems. These results support the basis 
for continuing the use of TTHM and HAA5 as indicators for controlling 
chlorinated DBPs. The data also reconfirmed that ground water systems 
require less monitoring than surface water systems based on lower and 
less variable DBP occurrence. For detailed analysis, see Stage 2 
Occurrence Assessment for Disinfectants and Disinfection Byproducts 
(USEPA 2003o).
2. Other Data Sources Used To Support the Proposal
    Table IV-1 summarizes the data sources other than the Information 
Collection Rule used to support the Stage 2 DBPR. The data from the 
Information Collection Rule is from large systems. To validate the 
conclusions drawn from analysis of the Information Collection Rule for 
small and medium systems, EPA compared these other data sources with 
the Information Collection Rule data. EPA found that there are 
significant similarities between large systems and medium and small 
systems with regard to source water quality (affecting DBP formation) 
and use of treatment technologies. Because of these similarities, EPA 
expects that small and medium systems would find DBP distribution 
system levels similar to those found in large systems following 
compliance with the Stage 1 DBPR requirements. For detailed discussion 
of this analysis, see Stage 2 Occurrence Assessment for Disinfectants 
and Disinfection Byproducts (USEPA 2003o) and Economic Analysis for the 
Stage 2 Disinfection Byproducts Rule (USEPA 2003i).

                                     Table IV-1.--Summary of Non-Information Collection Rule Occurrence Survey Data
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                           Geographic
              Data source                             Data collected                     representation        Number of plants  (By population served)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Information Collection Rule             Raw source water-(Large Systems) TOC        Random national           47 serving 100,000 or more.
 Supplemental Survey.                   Raw source water-(Small & Medium Survey      distribution by SW       40 serving 10,000-99,999.
                                         Systems) TOC, UV 254, bromide, turbidity,   source type \1\.         40 serving fewer than 10,000.
                                         pH, & temperature.
WaterStats............................  Population served and flows                 Random national           219 serving 100,000 or more.
                                        Raw source water--Water                      distribution.            623 serving 10,000-99,999.
                                        Quality Parameters (WQPs),                                            30 serving fewer than 10,000.
                                        Source water type.
                                        Finished water-WQPs, TTHM, HAAs
                                        Treatment-unit processes, disinfectant
                                         used.
National Rural Water Association        Population served and flows                 Random national           117 serving fewer than 10,000.
 Survey (NRWAS).                        Raw source water-temperatures, turbidity,    distribution.
                                         pH, and source water type, bromide, TOC,
                                         UV 254, alkalinity, calcium, and total
                                         hardness.
                                        Finished water-residence time estimate,
                                         total and individual THMs, individual
                                         HAAs and HAA5, HAA6, HAA9,TOC, UV 254,
                                         Bromide, Temperature, pH, free and total
                                         chlorine residual levels.
                                        Treatment-unit processes, disinfectant
                                         used.
State Data-Surface Water..............  Distribution system TTHM occurrence data.   AK, CA, IL, MN, MS, NC,   562 serving fewer than 10,000.
                                                                                     TX, WA \2\.
State Data-Ground Water...............  Distribution system TTHM occurrence data.   AK, CA, FL, IL, NC, TX,   2336 serving fewer than 10,000.
                                                                                     WA \2\.
Ground Water Supply Survey............  TOC and TTHM (one sample for each           Random national           979 total.
                                         parameter at the entry point to             distribution.
                                         distribution system.)
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Source type designations include flowing stream and lake/reservoir (Except for 7 large plants pre-selected).
\2\ Over 50 percent of each State's systems are represented. EPA believes that the data reasonably represent a full range of source water quality in
  small systems at the national level.


[[Page 49567]]

B. DBPs in Distribution Systems

    EPA wanted to understand DBP occurrence in distribution systems 
likely to exist after implementation of the Stage 1 DBPR. Such an 
understanding would enable EPA to recognize options on how to improve 
protection under the Stage 2 DBPR. The analysis of occurrence data to 
support the Stage 2 DBPR is complicated because available national 
occurrence data do not reflect the changes in occurrence resulting from 
the implementation of the Stage 1 DBPR. Many utilities have only 
recently changed their treatment to comply with the Stage 1 DBPR 
(subpart H systems serving 10,000 people or more were required to 
comply beginning January 2002) or are about to make changes in 
treatment to comply with this rule (subpart H systems serving fewer 
than 10,000 people and ground water systems are required to comply 
beginning January 2004).
    To address the above issue, EPA evaluated Stage 1 DBPR implications 
by using Information Collection Rule data from plants that would not 
exceed the Stage 1 DBPR TTHM and HAA5 MCLs as an annual average. The 
TTHM and HAA5 data consist of quarterly measurements in four locations 
in distribution systems associated with each Information Collection 
Rule treatment plant. Two samples were collected at sites representing 
average residence time (AVG1 and AVG2), one sample at a site intended 
to represent the maximum residence time (MAX), and one sample was 
reported as a distribution system equivalent (DSE). The DSE sample was 
generally representative of average residence times. EPA believes that 
the monitoring locations of the Information Collection Rule, while not 
necessarily being the same as the Stage 1 DBPR compliance monitoring 
sites, provide a close approximation of monitoring under the Stage 1 
DBPR. EPA recognizes, however, that data for plants that are in 
compliance with Stage 1 MCLs even without installing additional 
treatment (perhaps because of low source water TOC) are not necessarily 
reflective of plants that make treatment changes to comply with the 
Stage 1 DBPR.
1. DBPs Above the MCL Occur at Some Locations in a Substantial Number 
of Plants
    Figure IV-1 compares the TTHM running annual average (RAA) levels 
with the single highest TTHM concentration in the distribution system. 
Twenty one percent (60 of 290) of the Information Collection Rule 
plants had single TTHM concentrations higher than the 0.080 mg/L MCL. 
Figure IV-2 makes the same comparison for HAA5. Fourteen percent (40 of 
290) of the plants meeting the Stage 1 DBPR MCL had single HAA5 
concentrations higher than the 0.060 mg/L MCL. In systems with a low 
RAA for TTHM and HAA5, the highest single TTHM and HAA5 values are 
generally not much higher than the respective Stage 1 DBPR MCLs. 
However, as the RAAs increase, there is a greater likelihood of having 
peak levels above the MCLs. As the RAAs approach the Stage 1 DBPR MCLs, 
some of the distribution system single highest concentrations approach 
levels that are double the Stage 1 DBPR MCLs.
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2. Specific Locations in Distribution Systems Are Not Protected to MCL 
Levels
    Data from the Information Collection Rule show that the RAA 
compliance calculation may allow specific locations in a distribution 
system to regularly receive water with DBP levels that exceed the MCL. 
Figure IV-3 shows that five percent of plants (15 out of 290) had one 
or more locations that, on average, exceeded 0.080 mg/L as a TTHM LRAA 
for that same year. One of the 15 plants that exceeded a TTHM LRAA of 
0.080 mg/L did so at two locations. Of the 15 plants, the highest LRAA 
was between 0.080 and 0.090 mg/L at 10 plants, and between 0.090 and 
0.100 mg/L at 5 plants. Customers served at these locations regularly 
received water with TTHM concentrations somewhat higher than the MCL.
    Figure IV-4 shows similar results based on Information Collection 
Rule HAA5 data. Three percent of plants (eight of 290) exceeded 0.060 
mg/L as an LRAA, and three of these eight plants did so at two or three 
locations. Of the 8 plants, the highest LRAA was between 0.060 and 
0.070 mg/L at 5 plants, and between 0.070 and 0.075 mg/L at 3 plants. 
Among the 290 plants in the Information Collection Rule database 
meeting the Stage 1 MCLs, 19 plants have a maximum TTHM LRAA of 0.080 
mg/l or greater or a maximum HAA5 LRAA of 0.060 mg/l or greater (four 
plants exceeded both MCLs), though in no case did DBP levels at a given 
location consistently exceed the MCL by more than 20%.

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3. Stage 1 DBPR Maximum Residence Time Location May Not Reflect the 
Highest DBP Occurrence Levels
    The 1979 TTHM rule and Stage 1 DBPR monitoring locations must 
include a site reflection maximum residence time in the distribution 
system with the intent of capturing the highest DBP levels in the 
distribution system. The Information Collection rule referred to this 
specific location as MAX. The Information Collection rule data indicate 
two important results: (1) that monitoring locations identified as the 
maximum residence time locations often did not represent those 
locations with the highest DBP levels and (2) the highest TTHM and HAA5 
level often occurred at different points in the distribution system.
    Figure IV-5 illustrates that the highest TTHM and HAA5 LRAAs could 
be at any of the four Information Collection Rule sample locations in 
the distribution system or, in some cases, at the finished water 
location. Fifty percent of the plants evaluated have the highest TTHM 
LRAA concentration occurring at a site other than the maximum residence 
time monitoring site. over 60% of plants evaluated had the highest HAA5 
LRAA at a location other than the maximum residence time monitoring 
site.
    Figure IV-6, based on data from the National Rural Water Survey 
(NRWS), indicates that systems serving fewer than 10,000 people also 
frequently have their highest TTHM and HAAS levels at locations other 
than those intended to represent maximum residence time. The occurrence 
patterns indicated in Figures IV-5 and IV-6 may be due to several 
factors, such as HHA5 degrading over time in the distribution system, 
maximum residence time monitoring sites not actually representing the 
maximum residence time, or that using a simple estimation of maximum 
residence time cannot characterize a complex distribution system.
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    EPA also analyzed whether the highest LRAA for TTHM and HAA5 
occurred at the same location. If TTHM and HAA5 occur at the same 
location rather than different locations, fewer monitoring sites would 
be needed to represent TTHM and HAA5 occurrence. However, this is not 
the case. The Information Collection Rule and NRWA data sets, 
respectively, indicate that 49% and 44% of plants experienced their 
highest LRAA TTHM and HAA5 concentrations at different locations in the 
distribution system.
    For plants that did have their highest LRAA TTHM and HAA5 
concentrations at the same location, it was not necessarily the maximum 
residence time monitoring location. Figure IV-7 illustrates that for 
the Information Collection Rule plants with the highest TTHM and HAA5 
levels occurring at the same location, the highest TTHM and HAA5 LRAA 
simultaneously occurred at the maximum residence time monitoring 
location in 50% of the cases. Figure IV-8 illustrates that for the NRWA 
plants with the highest TTHM and HAA5 levels occurring at the same 
location, the highest TTHM and HAA5 LRAA simultaneously occurred at the 
maximum residence time (MAX) monitoring location in 64% of the cases.

C. Request for Comment

    EPA requests comment on the analysis presented in this section. Is 
EPA's approach for representing post Stage 1 DBPR occurrence 
appropriate? What other approaches might be used? Are the conclusions 
that EPA derives from the analysis appropriate?

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V. Discussion of Proposed Stage 2 DBPR Requirements

A. MCLG for Chloroform

1. What Is EPA Proposing Today?
    EPA is proposing an MCLG for chloroform of 0.07 mg/L based on a 
cancer reference dose (RfD), an assumption that a person drinks 2 
liters of water per day (the 90th percentile of intake rate for the 
U.S. population), and a relative source contribution (RSC) of 20 
percent. The MCLG is proposed at a level at which no adverse effects on 
the health of persons is anticipated with an adequate margin of safety. 
This conclusion is based on toxicological evidence that the 
carcinogenic effects of chloroform are an ultimate consequence of 
sustained tissue toxicity. The MCLG is set at a daily dose for a 
lifetime at which no adverse effects will occur because the sustained 
tissue toxicity, which is a key event in the cancer mode of action of 
chloroform, will not occur (USEPA 2001b).
    EPA believes that the RfD used for chloroform is protective of 
sensitive groups, including children. This RfD was developed by the EPA 
current method for developing RfDs based on animal data. The method is 
designed to be protective by taking human variability into account and 
assuming that the average human will be as sensitive as the most 
responsive animal species. EPA's understanding of the mode of action 
for chloroform does not indicate a uniquely sensitive subgroup or an 
increased sensitivity in children.
2. How Was This Proposal Developed?
    a. Background. EPA proposed a zero MCLG for chloroform in the 1994 
Stage 1 DBPR proposal (USEPA 1994b). Following the proposal, numerous 
toxicological studies on chloroform were published and were discussed 
in two Notices of Data Availability (NODAs) (USEPA 1997a; USEPA 1998e). 
The 1998 NODA presented substantial scientific data related to the mode 
of action as part of the chloroform risk assessment and requested 
comment on a chloroform MCLG of 0.3 mg/L that reflected a nonlinear 
mode of action. After considering comments on the NODAs, EPA determined 
that further deliberations with the Science Advisory Board (SAB) and 
stakeholders were needed before changing the MCLG for chloroform. Thus, 
EPA promulgated a chloroform MCLG of zero in the final Stage 1 DBPR 
(USEPA 1998c) and committed to conducting additional deliberations with 
the SAB and factoring the SAB's review into the Agency's Stage 2 DBPR 
rulemaking

[[Page 49577]]

process. The Agency consulted with the SAB in October 1999 (USEPA 
2000f).
    The Stage 1 DBPR MCLG of zero for chloroform was challenged, and 
the U.S. Court of Appeals for the District of Columbia Circuit issued 
an order vacating the zero MCLG (Chlorine Chemistry Council and 
Chemical Manufacturers Association v. EPA, 206 f.3d 1286 (D.C. Circuit 
2000)). EPA committed to the Court to propose a non-zero MCLG for 
chloroform in the upcoming proposed Stage 2 Disinfectants and 
Disinfection Byproducts Rule. EPA removed the MCLG for chloroform from 
its Stage 1 DBP NPDWR (USEPA 2000e). No other provision of the Stage 1 
DBPR was affected.
    b. Basis of the new chloroform MCLG. Based on an analysis of all 
the available scientific data on chloroform discussed in more detail 
below, EPA believes that chloroform dose-response is nonlinear and that 
chloroform is likely to be carcinogenic only under high exposure 
conditions. EPA's assessment of the cancer risk associated with 
chloroform exposure (USEPA 2001b) uses the principles of the 1999 EPA 
Proposed Guidelines for Carcinogen Risk Assessment (USEPA 1999a).
    The Proposed Guidelines for Carcinogen Risk Assessment, as reviewed 
by the public and the EPA SAB, reflect new science and are consistent 
with, and an extension of, the existing 1986 Guidelines for Carcinogen 
Risk Assessment (USEPA 1986). The 1986 guidelines provide for 
departures from default assumptions such as low dose linear 
extrapolation. For example, the 1986 EPA guidelines reflect the 
position of the Office of Science and Technology Policy (OSTP) that 
(OSTP 1985; Principle 26) ``[N]o single mathematical procedure is 
recognized as the most appropriate for low-dose extrapolation in 
carcinogenesis. When relevant biological evidence on mechanisms of 
action exists (e.g, pharmacokinetics, target organ dose), the models or 
procedure employed should be consistent with the evidence.'' The 1985 
guidelines go on to state ``The Agency will review each assessment as 
to the evidence on carcinogenesis mechanisms and other biological or 
statistical evidence that indicates the suitability of a particular 
extrapolation model.''
    i. Mode of action. EPA has fully evaluated the science on 
chloroform and concludes that chloroform is likely to be carcinogenic 
to humans under high exposure conditions that lead to cytotoxicity and 
regenerative hyperplasia in susceptible tissue; chloroform is not 
likely to be carcinogenic to humans at a dose level that does not cause 
cytotoxicity and cell regeneration (USEPA 1998e, USEPA 1998b, USEPA 
2001b).
    Chloroform's carcinogenic potential is indicated by animal tumor 
evidence (liver tumors in mice and renal tumors in both mice and rats) 
from inhalation and oral exposure. Data on metabolism, toxicity, 
mutagenicity and cellular proliferation contribute to an understanding 
of the mode of carcinogenic action. For chloroform, sustained or 
repeated cytotoxicity with secondary regenerative hyperplasia precedes, 
and is a key event for, hepatic and renal neoplasia.
    EPA believes that a DNA reactive mutagenic mode of action is not 
likely to be the predominant influence of chloroform on the 
carcinogenic process. EPA has concluded that the predominant mode of 
action involves cytotoxicity produced by the oxidative generation of 
highly reactive metabolites, followed by regenerative cell 
proliferation (USEPA 2001b). EPA further believes that the chloroform 
dose-response is nonlinear. The SAB final report states ``(t)he 
Subcommittee agrees with EPA that sustained or repeated cytotoxicity 
with secondary regenerative hyperplasia in the liver and/or kidney of 
rats and mice precedes, and is probably a causal factor for, hepatic 
and renal neoplasia'' (USEPA 2000f).
    ii. Metabolism. The cytochrome P450 isoenzyme CYP 2E1 is the 
primary enzyme catalyzing chloroform metabolism at low concentrations. 
Chloroform's carcinogenic effects involve oxidative generation of 
reactive and toxic metabolites (phosgene and hydrochloric acid [HCl]) 
and thus are related to its noncancer toxicities (e.g., liver or kidney 
toxicities). The electrophilic metabolite phosgene could react with 
macromolecules such as phosphotidyl inositols or tyrosine kinases which 
in turn could potentially lead to interference with signal transduction 
pathways (i.e., chemical messages controlling cell division), thus 
leading to carcinogenesis. Likewise, it is also plausible that phosgene 
reacts with cellular phospholipids, peptides and proteins resulting in 
generalized tissue injury. Glutathione, free cysteine, histidine, 
methionine and tyrosine are all potential reactants for electrophilic 
agents.
    At high concentrations, chloroform may undergo reductive metabolism 
which forms reactive dichloromethyl free radicals. These free radicals 
can contribute to lipid peroxidation and cause cytotoxicity.
    c. How the MCLG is derived. EPA continues to recognize the strength 
of the science in support of a nonlinear approach for estimating the 
carcinogenicity of chloroform. This science was affirmed by the 
Chloroform Risk Assessment Review Subcommittee of the EPA SAB Executive 
Committee which met on October 27-28, 1999 (USEPA 2000f). The SAB 
Subcommittee agreed that the nonlinear approach is most appropriate for 
the risk assessment of chloroform.
    Nonzero MCLGs are scientifically and statutorily supported. The 
statute requires that the MCLG be set where no known or anticipated 
adverse effects occur, allowing for an adequate margin of safety (56 FR 
3533; USEPA 1991b). Historically, EPA established MCLGs of zero for 
known or probable human carcinogens based on the principle that any 
exposure to carcinogens might represent some finite level of risk. If 
there is substantial scientific evidence, however, that indicates there 
is a ``safe threshold'', then a nonzero MCLG can be established with an 
adequate margin of safety (56 FR 3533; USEPA 1991a)).
    EPA would ideally like to use the delivered dose (i.e., the amount 
of key chloroform metabolites that actually reach the liver and cause 
cell toxicity) for calculating an RfD to support the MCLG. However, the 
required toxicokinetic data are not currently available. Thus, the RfD 
is calculated using the applied dose (i.e., the amount of chloroform 
ingested). The RfD is based on both the benchmark dose and the 
traditional no observed adverse effect level/lowest observed adverse 
effect level (NOAEL/LOAEL) approaches for hepatotoxicity in the most 
sensitive species, the dog. The MCLG is based on the RfD and calculated 
as follows:
[GRAPHIC] [TIFF OMITTED] TP18AU03.026

    i. Reference dose. The RfD for chloroform was estimated based on 
noncancer effects using both the benchmark dose and the traditional 
NOAEL/LOAEL approaches. For benchmark analysis, five relevant data sets 
including target organ toxicity, labeling index, histopathology in 
rodents, and liver toxicity in dogs (Heywood 1979) were evaluated. The 
effects seen in dogs are considered to be early signs of liver 
toxicity, preceding cytotoxicity, cytolethality and regenerative 
hyperplasia. Thus, the Heywood (1979) study, provides the most 
sensitive end point in the most sensitive species and is the most 
appropriate basis for the RfD.

[[Page 49578]]

    The 95% confidence lower bound on the dose associated with a 10% 
extra risk (LED10) is based on the prevalence of animals demonstrating 
liver toxicity. After an exposure adjustment to the LED10 (1.2 mg/kg/
day), an RfD of 0.01 mg/kg/day was calculated using an overall 
uncertainty factor of 100 (10 for interspecies extrapolation and 10 for 
protection of sensitive individuals) (USEPA 2001b).
    Coincidentally, the benchmark dose and the traditional NOAEL/LOAEL 
approaches yield the same RfD number (USEPA 2001b). The NOAEL/LOAEL 
approach is also based on the Heywood study (1979) which had a LOAEL of 
15 mg/kg/day for evidence of liver toxicity. After an exposure 
adjustment to the LOAEL (yielding 12.9 mg/kg/day), an RfD of 0.01 mg/
kg/day was calculated using an overall uncertainty factor of 1000 (10 
for interspecies extrapolation, 10 for protection of sensitive 
individuals, and 10 for using a LOAEL instead of a NOAEL) (USEPA 
2001b).
    ii. Relative source contribution. Another factor in determining the 
MCLG is the relative source contribution (RSC). The RSC is used when 
the MCLG is set at a level above zero. Its purpose is to ensure that 
the contribution to exposure from drinking tap water does not cause the 
lifetime daily exposure of persons to a contaminant to exceed RfD. The 
RSC is thus a factor used to make sure that the MCLG is protective even 
if persons are exposed to the contaminant by other routes (inhalation, 
dermal absorption) or other sources (e.g., food). If sufficient 
quantitative data are not available on exposure by other routes and 
sources, EPA has historically assumed that the RSC from drinking water 
is 20 percent of the total exposure, a value considered protective. If 
data indicate that contributions from other routes and sources are not 
significant, EPA has historically assumed a less conservative RSC of 80 
percent (54 FR 22,062, 22,069 (May 22, 1989)(USEPA 1989a), 56 FR at 
3535 (Jan 30, 1990)(USEPA 1991a), 59 FR 38,668, 38,678 (July 29, 
1994)(USEPA 1994b)).
    Today, EPA is proposing an assumption of a 20 percent RSC. This is 
in consideration of data which indicate that exposure to chloroform by 
other routes and sources of exposure may potentially contribute a 
substantial percentage of the overall exposure to chloroform.
    In the 1998 Stage 1 DBPR NODA, EPA considered an MCLG of 0.3 mg/L 
that was calculated using an RSC of 80 percent, based on the assumption 
that most exposure to chloroform is likely to come from ingestion of 
drinking water. In the final Stage 1 DBPR, EPA reconsidered this 
assumption in response to comments and in the light of data which 
indicate that exposure to chloroform by inhalation and dermal exposure 
may potentially contribute a substantial percentage of the overall 
exposure to chloroform depending on the activity patterns of 
individuals (USEPA 1998e) e.g., during showering, bathing, swimming, 
boiling water, clothes washing, and dishwashing. There is also 
potential exposure to chloroform by the dietary route. There are 
uncertainties regarding other possible highly exposed sub-populations, 
e.g., swimmers, those who use humidifiers, hot-tubs, and outdoor 
misters, persons living near industrial sources, people working in 
laundromats, and persons working with pesticides employing chloroform 
as a solvent (USEPA 1998b).
    A 1998 International Life Sciences Institute (ILSI) report 
evaluated the uptake of drinking water contaminants through the skin 
and by inhalation. The report noted that ``(i)n the case of chloroform, 
its high volatility leads to its rapid movement from liquid to air. 
Large water-use sources, such as showers, become dominant sources with 
respect to exposure'' and ``(t)he inhalation route is demonstrated to 
be the primary route for higher-volatility compounds (e.g., 
chloroform)'' (ILSI 1998). Weisel and Jo (1996) found that 
``approximately equivalent amounts of chloroform from water can enter 
the body by three different exposure routes, inhalation, dermal 
absorption, and ingestion, for typical daily activities of drinking and 
bathing.''
    Chloroform has been found in beverages, especially soft drinks, and 
food, particularly dairy products (Wallace, 1997). Wallace states that 
``ingestion (drinking tap water and soft drinks and eating certain 
dairy foods), inhalation (breathing peak amounts of chloroform emitted 
during showers or baths, and lower levels in indoor air from other 
indoor sources), and dermal absorption (during showers, baths, and 
swimming)'' each ``appear to be potentially substantial contributors to 
total exposure''.
    EPA estimates that for the median individual, ingestion of total 
tap water (assuming certain activity patterns, habits, and home 
characteristics) can contribute roughly 28 percent of the total dose of 
chloroform (USEPA 2001a). With assumptions as described, tap water 
ingestion is a portion of exposure through fluid intake which 
contributes about 34 percent of the total dose, inhalation accounts for 
about 31 percent of the total dose, ingestion of foods contributes 
another 27 percent of the overall dose, and dermal absorption 
(primarily during showering) adds slightly less than 8 percent of the 
total dose. These exposure percentages are based on average daily doses 
(mean chloroform intake for adults) for each source and route of 
exposure under specific conditions. They do not take into account the 
considerable variability in several factors across the population. For 
instance, intake of drinking water or particular foods and length of 
shower varies from day-to-day, as do home air turnover rates and 
ventilation. Different areas in the United States vary with respect to 
these factors and chloroform concentrations in food. Thus, although the 
28 percent for the median individual is based on reasonable 
assumptions, uncertainty remains.
    Given the uncertainties of estimation, EPA believes available 
analyses point to the RSC of 20 percent as the appropriate default 
(i.e., 20 percent of exposure to chloroform comes from drinking tap 
water alone). EPA also believes that this default is protective of 
public health and is a more reasonable choice than choosing any 
particular estimate because of the assumptions and uncertainties 
involved with each estimation. Hence, EPA is proposing the MCLG based 
on the RSC default of 20 percent which supports the adequacy of the 
margin of safety associated with the MCLG.
    iii. Water ingestion and body weight assumptions. In MCLG 
calculations, EPA assumes the 90th percentile water ingestion of 2 
liters (roughly equivalent to a half gallon) per day (USEPA 2000a). The 
use of a conservative consumption estimate is consistent with the 
objective of setting an MCLG that is protective. EPA also uses a 
default adult body weight of 70 kg (equal to 154 pounds) for the RfD 
since dose is calculated from lifetime studies of animals and compared 
to lifetime exposure for humans.
    iv. MCLG calculation. The MCLG is calculated to be 0.07 mg/L using 
the following assumptions: an adult tap water consumption of 2 L per 
day for a 70 kg adult, and a relative source contribution of 20%:

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    EPA concludes that an MCLG of 0.07 mg/L based on protection against 
liver toxicity will be protective against carcinogenicity given that 
the mode of action for chloroform involves cytotoxicity as a key event 
preceding tumor development. Therefore, the recommended MCLG for 
chloroform is 0.07 mg/L.
    v. Other considerations. The evidence supports similarity of 
potential response in children and adults. The basic biology of 
toxicity caused by cell damage due to oxidative damage is expected to 
be the same. There is nothing about the incidence and etiology of liver 
and kidney cancer in children to indicate that they would be inherently 
more sensitive to this mode of action. Most importantly in this case, 
children appear to be no different quantitatively in ability to carry 
out the oxidative metabolism step for the induction of toxicity and 
cancer and may, as fetuses, be less susceptible (USEPA 1999c).
    Some commenters on the March 1998 NODA were concerned that EPA did 
not take drinking water epidemiology studies into account in its 
evaluation of chloroform risk. EPA believes that while the 
epidemiologic evidence suggests that chlorinated drinking water may be 
associated with certain cancers and reproductive, developmental effects 
pertinent to the risk of disinfectant byproduct mixtures, it does not 
provide insight into the risk from chloroform specifically. The SAB 
noted that ``(t)he goal of the draft risk assessment (the isolation of 
the effect of chloroform in drinking water) makes the extensive 
epidemiologic evidence on drinking water disinfection byproducts 
largely irrelevant'' to the specific question of chloroform health 
risks because, in the available studies, chloroform cannot be isolated 
from other disinfection byproducts that may be in the drinking water 
(USEPA 2000f). The SAB noted that ``the epidemiologic evidence is quite 
pertinent to the broader question of most direct regulatory concern, 
namely disinfection byproducts in the aggregate''.
    d. Feasibility of other options. During the development of the MCLG 
for chloroform, EPA considered a number of options for both the 
chloroform MCLG and the TTHM MCL. Today, EPA is proposing the preferred 
option of a 0.07 mg/L MCLG for chloroform. EPA primarily considered two 
other options which are discussed in more detail later: a 0.07 mg/L 
MCLG for chloroform in conjunction with developing MCLs for each of the 
individual TTHMs (i.e., 4 MCLs and 4 MCLGs for the THMs); and 
developing a single combined MCLG for TTHM rather than developing a 
separate MCLG for each of the THMs.
    EPA considered developing separate MCLGs and MCLs for each THM. 
Under this strategy, EPA would determine an MCL as close to the 
individual MCLGs as is technically feasible, taking cost into 
consideration, for each THM. EPA would propose an MCLG of 0.07 mg/L for 
chloroform and maintain the Stage 1 DBPR MCLGs for BDCM, DBCM, and 
bromoform (USEPA 1998c). EPA analyzed the impact such an MCL strategy 
would have and ultimately rejected this option. This approach 
represents a fundamental shift from the TTHM strategy agreed to by 
stakeholders and EPA as part of the M-DBP negotiation process and 
reflected in the 1998 Stage 1 DBPR. In addition, one important 
component of the existing single MCL is that TTHMs are an indicator for 
other DBPs. Developing a separate MCL for each THM would move away from 
this indicator approach. Because precursor and DBP occurrence 
measurements are highly variable, both temporally and geographically, 
determining technical feasibility for best available technology (BAT) 
would be difficult. Compliance with individual THM standards would be 
very different from compliance based on a sum of the four THMs and it 
is not clear what treatment technology shifts would be needed. This 
problem would be particularly exacerbated in areas with high bromide, 
such as California. EPA also projected that States would have a 
difficult time overseeing (e.g., variances, exemptions, etc.) the more 
complicated rule that would result from this option.
    EPA considered establishing a single combined MCLG for TTHM. There 
is precedent for using a toxicity equivalency quotient (analogous to a 
combined MCLG) for dioxin and coplanar PCBs (USEPA 2000o, Draft Dioxin 
Reassessment). From a scientific standpoint, a combined MCLG approach 
requires that the chemicals have a similar mode of action and health 
endpoint. Chemicals within each of the dioxin and coplanar PCB classes 
have the same mode of action and endpoint (target tissue). Within the 
PCB class, noncoplanar PCBs have a different mode of action than the 
coplanar PCBs. Noncoplanar PCBs are, therefore, not included in the 
toxicity equivalency quotient for coplanar PCBs. In the case of the 
disinfection byproducts, EPA believes that the THMs have different 
modes of action and health endpoints. One of the THMs is a liver 
carcinogen (chloroform) with a mode of action dependent on 
cytolethality; two are DNA-reactive carcinogens (bromodichloromethane--
large intestine and kidney tumors, and bromoform--large intestine 
tumors); and one is a nonlinear non-carcinogen (dibromochloromethane) 
which is a liver toxicant. EPA therefore, chose not to develop a 
combined MCLG for TTHM. Consequently, after considering this 
alternative option in some detail, EPA is today proposing an MCLG of 
0.07 mg/L for chloroform.
3. Request for Comment
    Based on the information presented previously, EPA is proposing an 
MCLG for chloroform of 0.07 mg/L. EPA requests comments on the MCLG and 
on EPA's cancer assessment for chloroform. EPA also requests comments 
on the RfD, the default RSC of 20 percent, and the tap water 
consumption and body weight assumptions used in the MCLG calculation. 
EPA solicits additional data on chloroform exposure via other sources 
and routes. EPA requests comment on the other options for developing 
the chloroform MCLG that the Agency considered.

B. MCLGs for THMs and HAAs

1. What Is EPA Proposing Today?
    Today EPA is proposing new MCLGs of 0.02 mg/L for TCAA and 0.03 mg/
L for MCAA based on new toxicological data. As a part of the Stage 1 
DBPR, EPA finalized an MCLG of 0.3 mg/L for TCAA. The Stage 1 DBPR did 
not include an MCLG for MCAA (although it was included as one of the 
five haloacetic acids in the HAA5 MCL). With the exception of 
chloroform, discussed above, and these two HAAs, EPA is not revising 
any of the other MCLGs that were finalized in the Stage 1 DBPR. No 
significant new studies that would change EPA's MCLG estimates for 
BDCM, DBCM, bromoform, or DCAA have been published since the Stage 1 
DBPR. See section III for a summary of new health effects data.
2. How Was This Proposal Developed?
    EPA reviewed the available literature on BDCM, DBCM, bromoform, 
DCAA and determined that there was no new

[[Page 49580]]

information that would cause EPA to revise its MCLG estimates. New 
toxicology studies on reproductive and developmental effects and cancer 
are summarized in sections III.B. and III.D. of today's proposal.
    EPA is proposing new MCLGs for TCAA and MCAA. The health effects 
information and studies described in the following two sections that 
support the proposed MCLGs are summarized from the Addendum to the 
Criteria Document for Monochloroacetic Acid and Trichloroacetic Acid 
(USEPA 2003b). The occurrence of MCAA and TCAA are discussed in the 
Stage 2 Occurrence Assessment for Disinfectants and Disinfection 
Byproducts (USEPA 2003o). a. Trichloroacetic acid. In the final Stage 1 
DBPR, EPA based its health effects assessment of TCAA on developmental 
toxicity and limited evidence of carcinogenicity (USEPA 1998c). Since 
then, the Agency has decided that the RfD based on a developmental 
LOAEL yields a less conservative RfD than that based on liver toxicity 
derived from the study by DeAngelo et al. (1997). Thus, the Agency has 
reassessed the health effects of TCAA based on liver toxicity and 
revised the RfD and MCLG.
    TCAA induces systemic, noncancer effects in animals and humans that 
can be grouped into three categories: metabolic alterations, liver 
toxicity; and developmental toxicity. The primary site of TCAA toxicity 
is the liver (USEPA1994a; Dees and Travis, 1994; Acharya et al. 1995; 
Acharya et al. 1997; DeAngelo et al.1997).
    The liver has consistently been identified as a target organ for 
TCAA toxicity in short-term (Goldsworthy and Popp, 1987; DeAngelo et 
al. 1989; Sanchez and Bull, 1990) and longer-term (Bull et al. 1990; 
Mather et al. 1990; Bhat et al. 1991) studies. Peroxisome proliferation 
has been a primary endpoint evaluated, with mice reported to be more 
sensitive to this effect than rats. More recent studies have confirmed 
these earlier findings. TCAA-induced peroxisome proliferation was 
observed in B6C3F1 mice exposed for 10 weeks to doses as low as 25 mg/
kg/day (Parrish et al. 1996), while in rats exposed to TCAA for up to 
104 weeks (DeAngelo et al. 1997), peroxisome proliferation was observed 
at 364 mg/kg/day, but not at 32.5 mg/kg/day. Increased liver weight and 
significant increases in hepatocyte proliferation have been observed in 
short-term studies in mice at doses as low as 100 mg/kg/day (Dees and 
Travis, 1994), but no increase in hepatocyte proliferation was noted in 
rats given TCAA at similar doses (DeAngelo et al. 1997). More clearly 
adverse liver toxicity endpoints, including increased serum levels of 
liver enzymes (indicating leakage from cells) or histopathological 
evidence of necrosis, have been reported in rats, but generally only at 
high doses. For example, in a rat chronic drinking water study, 
increased hepatocyte necrosis was observed at a dose of 364 mg/kg/day 
(DeAngelo et al. 1997).
    In the DeAngelo et al.(1997) study, groups of 50 male F344 rats 
were administered TCAA in drinking water, at 0, 50, 500, or 5000 mg/L, 
resulting in time-weighted mean daily doses of 0, 3.6, 32.5, or 364 mg/
kg for 104 weeks. There were no significant differences in water 
consumption or survival between the control and treatment groups. 
Exposure to the high dose of TCAA resulted in a significant decrease in 
body weight of 11% at the end of the study. The absolute but not 
relative liver weight was decreased at the high dose. Complete necropsy 
and histopathology examination showed mild hepatic cytoplasmic 
vacuolization in the two low-dose groups, but not in the high-dose 
group. The severity of hepatic necrosis was increased mildly in the 
high-dose animals. Analyses of serum aspartate aminotransferase (AST) 
and alanine aminotransferase (ALT) activities at the end of exposure 
showed a significant decrease in AST activity in the mid-dose group and 
a significant increase in ALT level in the high-dose group. Since 
increased serum ALT or AST levels reflect hepatocellular necrosis, the 
increased ALT at the high dose is considered an adverse effect, while a 
non-dose related decrease of AST is not. Peroxisome proliferation was 
increased significantly in the high-dose animals. There was no evidence 
of any exposure-related increase in hepatocyte proliferation. Based on 
the significant decrease in body weight (=10%), minimal 
histopathology changes, and increased serum ALT level, the high dose of 
364 mg/kg/day is considered the LOAEL and the mid dose of 32.5 mg/kg/
day is considered the NOAEL.
    There are no reproductive toxicity studies of TCAA. The results of 
an in vitro fertilization assay indicated that TCAA might decrease 
fertilization (Cosby and Dukelow, 1992). The available data suggest 
that TCAA is a developmental toxicant. TCAA increased resorptions, 
decreased implantations, and increased fetal cardiovascular 
malformations when administered to pregnant rats at 291 mg/kg/day 
(Johnson et al. 1998) on gestation days 1-22. In another study, 
decreased fetal weight and length, and increased cardiovascular 
malformations were observed when pregnant rats were administered 330 
mg/kg/day TCAA by gavage during gestation days 6 to 15 (Smith et al. 
1989). Neither of these studies identified a NOAEL. The results of in 
vitro developmental toxicity assays, including mouse and rat whole-
embryo culture (Saillenfait et al. 1995; Hunter et al. 1996) and frog 
embryo teratogenesis assay--Xenopus (FETAX) (Fort et al. 1993) yielded 
positive results. The Hydra test system (Fu et al. 1990) produced 
negative results.
    TCAA has been reported to induce liver tumors in mice but not in 
rats (USEPA 1994a). This observation has also been made in more recent 
drinking water studies. Pereira (1996) observed an increased incidence 
of hepatocellular adenomas and carcinomas in female B6C3F1 mice at 
doses of 262 mg/kg/day and higher after 82 weeks. In contrast, no 
increase in neoplastic liver lesions were found in F344 rats given 
doses up to 364 mg/kg/day for 104 weeks (DeAngelo et al. 1997). In 
addition, a variety of recent mechanistic studies have observed that 
TCAA either induced or promoted liver tumors in mice (Ferreira-Gonzalez 
et al. 1995; Pereira and Phelps, 1996; Tao et al. 1996; Latendresse and 
Pereira, 1997; Stauber and Bull, 1997; Tao et al. 1998).
    Recent mutagenicity data have provided mixed results (Giller et al. 
1997; DeMarini et al. 1994; Harrington-Brock et al. 1998). TCAA did not 
induce oxidative DNA damage in mice following dosing for either 3 or 10 
weeks (Parrish et al. 1996). Studies on DNA strand breaks and 
chromosome damage produced mixed results (Nelson and Bull, 1988; Chang 
et al. 1991; Mackay et al. 1995; Harrington-Brock et al. 1998).
    According to the 1999 Draft Guidelines for Carcinogen Risk 
Assessment (USEPA 1999a), a compound is appropriately classified as 
``Suggestive Evidence of Carcinogenicity, but Not Sufficient to Assess 
Human Carcinogenic Potential'' when ``the evidence from human or animal 
data is suggestive of carcinogenicity, which raises a concern for 
carcinogenic effects but is judged not sufficient for a conclusion as 
to human carcinogenic potential''. Based on uncertainty surrounding the 
relevance of the liver tumor data in B6C3F1 mice, TCAA can best be 
described as ``Suggestive Evidence of Carcinogenicity, but Not 
Sufficient to Assess Human Carcinogenic Potential'' under the 1999 
Draft Guidelines for Carcinogen Risk Assessment. Thus a quantitative 
estimate of cancer potency is not supported.

[[Page 49581]]

    The RfD for TCAA of 0.03 mg/kg/day is based on the NOAEL of 32.5 
mg/kg/day for liver histopathological changes identified by DeAngelo et 
al. (1997). The RfD includes an uncertainty factor of 1000 (composite 
uncertainty factor consisting of three factors of 10 chosen to account 
for extrapolation from a NOAEL in animals, inter-individual variability 
in humans, and insufficiencies in the database, including the lack of 
full histopathological data in a second species, the lack of a 
developmental toxicity study in second species, and the lack of a 
multi-generation reproductive study).
    The MCLG is calculated to be 0.02 mg/L using the following 
assumptions: an adult tap water consumption of 2 L of tap water per day 
for a 70 kg adult, a relative source contribution (RSC) of 20%, and an 
additional safety factor to account for possible carcinogenicity. EPA 
has traditionally applied an additional safety factor of 1-10 beyond 
the uncertainty factors included in the RfD to the MCLG to account for 
possible carcinogenicity in cases where there is limited evidence of 
carcinogenicity from drinking water, considering weight of evidence, 
pharmacokinetics, potency and exposure (USEPA 1994b, p.38678). EPA is 
proposing this additional safety factor of 10 for TCAA for the 
following reasons: TCAA causes liver tumors in mice but does not do so 
in rats. In addition, although peroxisome proliferation (a mode of 
action of limited relevance to humans) may play a role in the 
development of the mouse tumors, rats also exhibit a peroxisomal 
proliferative response after exposure to TCA, yet do not develop 
tumors. Other data suggest that promotion of initiated cells and/or 
disrupted cell signaling may be involved in the mode of action for the 
mouse tumors. Together these factors argue against quantification of 
the mouse liver tumors using linear extrapolation from the dose-
response curve, but are not sufficient to rule out concern for a 
tumorigenic response. Accordingly, EPA has employed the ten-fold 
additional safety factor in determination of the Lifetime Health 
Advisory for TCAA. EPA requests comment on the use of 10 as the 
additional safety factor for possible carcinogenicity.
[GRAPHIC] [TIFF OMITTED] TP18AU03.024

    An RSC factor of 20% is used to account for exposure to TCAA in 
sources other than tap water, such as ambient air and food. Although 
TCAA is nonvolatile and inhalation while showering is not expected to 
be a major contribution to total dose, rain waters contain 0.01-1.0 
[mu]g/L of TCAA (Reimann et al. 1996) and it can be assumed to be 
detected in the atmosphere. Limited data on concentrations of TCAA in 
air (NATICH 1993) indicate inhalation of TCAA in ambient air may 
contribute to overall exposure. Concentrations of TCAA that have been 
measured in a limited selection of foods including vegetables, fruits, 
grain and bread (Reimann et al. 1996) are comparable to that in water. 
About 3 to 33% of TCAA in cooking water have been reported to be taken 
up by the food during cooking in a recent research summary (Raymer et 
al. 2001). In addition, there are uses of chlorine in food production 
and processing, and TCAA may occur in food as a byproduct of 
chlorination (USEPA 1994a). Therefore, ingestion of TCAA in food may 
also contribute to the overall exposure. A recent dermal absorption 
study of DCAA and TCAA from chlorinated water suggested that the dermal 
contribution to the total doses of DCAA and TCAA from routine household 
uses of drinking water is less than 1% (Kim and Weisel, 1998).
    b. Monochloroacetic acid. Subchronic and chronic oral dosing 
studies suggest that the primary targets for MCAA-induced toxicity 
include the heart and nasal epithelium. In a 13-week oral gavage study, 
decreased heart weight was observed at 30 mg/kg/day and cardiac lesions 
progressed in severity with increasing dose. Liver and kidney toxicity 
were only observed at higher doses (NTP 1992). In a two-year study, 
decreased survival and nasal and forestomach hyperplasia were observed 
in mice at 50 mg/kg/day (NTP 1992). A more recent study confirms the 
heart and nasal cavities as target sites for MCAA. DeAngelo et al. 
(1997) noted decreased body weight at 26.1 mg/kg/day and myocardial 
degeneration and inflammation of the nasal cavities in rats exposed to 
doses of 59.9 mg/kg/day for up to 104 weeks.
    No studies were located on the reproductive toxicity of MCAA and 
the potential developmental toxicity of MCAA has not been adequately 
tested. Two developmental toxicity studies were identified. Johnson et 
al. (1998) reported markedly decreased maternal weight gain, but no 
developmental effects, in rats exposed to 193 mg/kg/day MCAA through 
gestation days 1-22, only fetal heart was examined. In contrast, in a 
published abstract, Smith et al. (1990) reported an increase in 
cardiovascular malformations when pregnant rats were exposed to 140 mg/
kg/day; this was also the LOAEL for maternal toxicity, based on marked 
decreases in weight gain. MCAA was noted as a potential developmental 
toxicant in in vitro screening assays using Hydra (Fu et al. 1990; Ji 
et al. 1998).
    MCAA has yielded mixed results in genotoxicity assays (USEPA 1994a; 
Giller et al. 1997), but has not induced a carcinogenic response in 
chronic rodent bioassays (NTP 1992; DeAngelo et al. 1997). In chronic 
oral gavage studies, a LOAEL of 15 mg/kg/day (the lowest dose tested) 
for decreased survival was identified in rats. In mice the NOAEL was 50 
mg/kg/day and the LOAEL was 100 mg/kg/day for nasal and forestomach 
epithelium hyperplasia (NTP 1992). In a more recent chronic study, 
DeAngelo et al. (1997) reported a LOAEL of 3.5 mg/kg/day in rats given 
MCAA in their drinking water, based on increased absolute and relative 
spleen weight. Although spleen weight was decreased at the mid and high 
doses, this might reflect the masking effect of overt toxicity. As 
evidence for this, decreased body weight (10%), liver, 
kidney, and testes weight changes were reported beginning at the next 
higher dose of 26.1 mg/kg/day. No increased spleen weight was reported 
in the NTP (1992) bioassays, but the lowest dose in rats caused severe 
toxicity, and the lowest dose in mice was more than an order of 
magnitude higher than the LOAEL in the DeAngelo et al. (1997) study.
    According to the 1999 Draft Guidelines for Carcinogen Risk 
Assessment (USEPA 1999a), a compound is appropriately classified as 
``Not Likely to be Carcinogenic to Humans'' when it has ``been 
evaluated in at least two well-conducted studies in two appropriate 
animal species without demonstrating carcinogenic effects.'' MCAA can 
best be described as ``Not Likely to be Carcinogenic to Humans'' under 
the 1999 Draft Guidelines for Carcinogen Risk Assessment.

[[Page 49582]]

    The RfD for MCAA of 0.004 mg/kg/day is based on a LOAEL of 3.5 mg/
kg/day for increased spleen weight in rats (DeAngelo et al. 1997) and 
application of an uncertainty factor of 1000 (composite uncertainty 
factor consisting of two factors of 10 chosen to account for 
extrapolation from an animal study, and inter-individual variability in 
humans; as well as two factors of 3 for extrapolation from a minimal 
effect LOAEL, and insufficiencies in the database, including the lack 
of adequate developmental toxicity studies in two species, and the lack 
of a multi-generation reproductive study). Two developmental toxicity 
studies have been reported (Johnson et al. 1998; Smith et al. 1990), 
but the NOAELs yielded less conservative RfDs. The study by DeAngelo et 
al (1997) is the most appropriate for derivation of the RfD because it 
identifies the lowest LOAEL, and dosing was in drinking water, which is 
more appropriate for human health risk assessment.
    The MCLG is calculated to be 0.03 mg/L using the following 
assumptions: an adult tap water consumption of 2 L of tap water per day 
for a 70 kg adult, and a relative source contribution of 20 %.
[GRAPHIC] [TIFF OMITTED] TP18AU03.025

    An RSC factor of 20% is used to account for exposure to MCAA in 
other sources in addition to tap water. Although MCAA is nonvolatile 
and inhalation while showering is not expected to be a major 
contribution to total dose, rain waters contain 0.05-9 [mu]g/L of MCAA 
(Reimann et al. 1996) and it can be assumed to be detected in the 
atmosphere. Presence of MCAA has also been reported in rain waters; 
thus, inhalation of MCAA in ambient air may contribute to overall 
exposure. Concentrations of MCAA that have been measured in a limited 
selection of foods including vegetables, fruits, grain and bread 
(Reimann et al. 1996) are comparable to that in water. About 2.5 to 62% 
of MCAA in cooking water has been reported to be taken up by food 
during cooking in a recent research summary (Raymer et al. 2001). In 
addition, there are uses of chlorine in food production and processing, 
and MCAA may occur in food as a byproduct of chlorination (USEPA 
1994a). Therefore, ingestion of MCAA in food may also contribute to the 
overall exposure. Assuming dermal absorption rate of MCAA is similar to 
DCAA, dermal contribution to the total doses of MCAA from routine 
household uses of drinking water should be minor (see V.B.2.a.).
3. Request for Comment
    EPA requests comment on the new MCLGs for TCAA (0.02 mg/L) and MCAA 
(0.03 mg/L) and all the factors incorporated in the derivation of the 
MCLGs, including the RfDs and RSCs. EPA also solicits health effect 
information on DBAA and monobromoacetic acid (MBAA), for which MCLGs 
have not yet been established.

C. Consecutive Systems

    Today's proposal includes provisions for consecutive systems, which 
are public water systems that purchase or otherwise receive finished 
water from another water system (a wholesale system). As described in 
this section, consecutive systems face particular challenges in 
providing water that meets regulatory standards for DBPs and other 
contaminants whose concentration can increase in the distribution 
system. Moreover, current regulation of DBP levels in consecutive 
systems varies widely among States. In consideration of these factors, 
EPA is proposing monitoring, compliance schedule, and other 
requirements specifically for consecutive systems. These requirements 
are intended to facilitate compliance by consecutive systems with MCLs 
for TTHM and HAA5 under the Stage 2 DBPR. Further, this approach will 
help to ensure that consumers in consecutive systems receive equivalent 
public health protection. This section begins with a summary of how EPA 
proposes to regulate consecutive systems under the Stage 2 DBPR. The 
intent of this section is to provide an overview of all consecutive 
system requirements in today's proposal. Detailed explanations of these 
requirements are provided in later sections of this preamble. The 
overview of consecutive system requirements is followed by an 
explanation of why EPA has taken this approach to consecutive systems 
in today's proposal, including recommendations from the Stage 2 M-DBP 
Federal Advisory Committee.
1. What Is EPA Proposing Today?
    As public water systems, consecutive systems must provide water 
that meets the MCLs for TTHM and HAA5 under the proposed Stage 2 DBPR, 
and must carry out associated monitoring, reporting, recordkeeping, 
public notification, and other requirements. The following discussion 
summarizes how the Stage 2 DBPR requirements apply to consecutive 
systems, beginning with a series of definitions. Later sections of this 
preamble provide further details as noted.
    a. Definitions. To address consecutive systems in the Stage 2 DBPR, 
the Agency must define them, along with a number of related terms.
    EPA is proposing to define a consecutive system in the Stage 2 DBPR 
as a public water system that buys or otherwise receives some or all of 
its finished water from one or more wholesale systems for at least 60 
days per year. In addition to buying finished water, some consecutive 
systems also operate a treatment plant (meaning a plant that treats 
source water to produce finished water). As described in section V.I., 
monitoring requirements under the Stage 2 DBPR proposal differ 
depending on whether a consecutive system buys all of its finished 
water year-round or, alternatively, produces some of its finished water 
through treating source water.
    EPA proposes to define finished water as water that has been 
introduced into the distribution system of a public water system and is 
intended for distribution without further treatment, except that 
necessary to maintain water quality (such as booster disinfection). 
With this definition, water entering the distribution system is 
finished water even if a system subsequently applies additional 
treatment like booster disinfection to maintain a disinfectant residual 
throughout the distribution system.
    In today's proposal, EPA defines a wholesale system as a public 
water system that treats source water and then sells or otherwise 
delivers finished water to another public water system for at least 60 
days per year. Delivery may be through a direct connection or through 
the distribution system of another consecutive system. Under this 
definition, a consecutive system that passes water from a wholesaler to 
another consecutive system, and that does not also treat source water, 
is not

[[Page 49583]]

a wholesale system. Rather, the system that actually produces the 
finished water is responsible for wholesale system requirements under 
the proposed Stage 2 DBPR.
    A consecutive system entry point is defined as a location at which 
finished water is delivered at least 60 days per year from a wholesale 
system to a consecutive system. Section V.I. presents the relationship 
between consecutive system entry points and proposed Stage 2 DBPR 
monitoring requirements. The combined distribution system is the 
interconnected distribution system consisting of the distribution 
systems of wholesale systems and of the consecutive systems that 
receive finished water from those wholesale system(s).
    b. Monitoring. For consecutive systems that both purchase finished 
water and treat source water to produce finished water for at least 
part of the year, EPA is proposing monitoring requirements under a 
treatment plant-based approach, described in section V.I. This is the 
approach proposed for non-consecutive systems under the Stage 2 DBPR as 
well. Under this approach, the sampling requirements for consecutive 
systems will be influenced by both the number of treatment plants 
operated by the system and the number of consecutive system entry 
points, as well as population served and source water type.
    For consecutive systems that purchase all of their finished water 
year-round, EPA is proposing monitoring requirements under a 
population-based approach, also described in section V.I. Under the 
population-based approach, the population of the consecutive system 
will determine the sampling requirements. EPA believes this approach is 
more appropriate than plant-based monitoring because these consecutive 
systems do not have treatment plants. As noted in section V.I., EPA is 
requesting comment on extending population-based monitoring to all 
systems, including non-consecutive systems. EPA has prepared draft 
guidance for implementing the IDSE monitoring requirements (described 
in section V.H.) using the population-based approach (USEPA 2003j).
    EPA is also proposing that States have the opportunity to specify 
alternative monitoring requirements for multiple consecutive systems in 
a combined distribution system. This option allows States to consider 
complex consecutive system configurations for which alternative 
monitoring strategies might be more appropriate. As a minimum under 
such an approach, each consecutive system must collect at least one 
sample among the total number of samples required for the combined 
distribution system and will base compliance on samples collected 
within its distribution system. The consecutive system is responsible 
for ensuring that required monitoring is completed and the system is in 
compliance. The consecutive system may conduct the monitoring itself or 
arrange for the monitoring to be done by the wholesale system or 
another outside party. Whatever approach it chooses, the consecutive 
system must document its monitoring strategy as part of its DBP 
monitoring plan.
    Finally, EPA is proposing that consecutive systems not conducting 
disinfectant residual monitoring comply with the monitoring 
requirements and MRDLs for chlorine and chloramines.
    c. Compliance schedules. EPA is proposing that consecutive systems 
of any size comply with the requirements of the Stage 2 DBPR on the 
same schedule as required for the largest system in the combined 
distribution system. This includes the schedule for carrying out the 
IDSE, described in section V.H, and for meeting the Stage 2B MCLs for 
TTHM and HAA5, described in section V.D. As discussed later in this 
section, EPA is proposing simultaneous compliance schedules under the 
Stage 2 DBPR for all systems (both wholesalers and consecutive systems) 
in a combined distribution system because this may allow for more cost-
effective compliance with TTHM and HAA5 MCLs. This is also consistent 
with the recommendations of the Stage 2 M-DBP Advisory Committee. See 
section V.J for details of compliance schedule requirements.
    d. Treatment. While consecutive systems often do not need to treat 
finished water received from a wholesale system, they may need to 
implement procedures to control the formation of DBPs in the 
distribution system. For consecutive systems, EPA is proposing that the 
BAT for meeting TTHM and HAA5 MCLs is chloramination with management of 
hydraulic flow and storage to minimize residence time in the 
distribution system. This BAT stems from the recognition that treatment 
to remove already-formed DBPs or minimize further formation is 
different from treatment to prevent or reduce their formation. See 
section V.F for additional information on BATs and their role in 
compliance with MCLs.
    e. Violations. Under this proposal, monitoring and MCL violations 
are assigned to the PWS where the violation occurred. Several examples 
are as follows:

--If a consecutive system has hired its wholesale system under contract 
to monitor in the consecutive system and the wholesale system fails to 
monitor, the consecutive system is in violation because it has the 
legal responsibility for monitoring under State/EPA regulations.
--If monitoring results in a consecutive system indicate an MCL 
violation, the consecutive systems is in violation because it has the 
legal responsibility for complying with the MCL under State/EPA 
regulations. The consecutive system may set up a contract with its 
wholesale system that details water quality delivery specifications.
--If a wholesale system has a violation and provides that water to a 
consecutive system, the wholesale system is in violation. Whether the 
consecutive system is in violation will depend on the situation. The 
consecutive system will also be in violation unless it conducted 
monitoring that showed that the violation was not present in the 
consecutive system.
    f. Public notice and consumer confidence reports. The 
responsibilities for public notification and consumer confidence 
reports rest with the individual system. Under the Public Notice Rule 
and Consumer Confidence Report Rule, the wholesale system is 
responsible for notifying the consecutive system of analytical results 
and violations related to monitoring conducted by the wholesale system. 
Consecutive systems are required to conduct appropriate public 
notification after a violation (whether in the wholesale system or the 
consecutive system). In their consumer confidence report, consecutive 
systems must include results of the testing conducted by the wholesale 
system unless the consecutive system conducted equivalent testing that 
indicated the consecutive system was in compliance, in which case the 
consecutive system reports its own compliance monitoring results.
    g. Recordkeeping and reporting. Consecutive systems are required to 
keep all records required of PWSs regulated under this rule. They are 
also required to report to the State monitoring results, violations, 
and other actions, and are required to consult with the State after a 
significant excursion.
    h. State special primacy conditions. EPA is aware that due to the 
complicated wholesale system-consecutive system relationships that

[[Page 49584]]

exist nationally, there will be cases where the standard monitoring 
framework proposed today will be difficult to implement. Therefore, the 
Agency is proposing to allow States to develop, as a special primacy 
condition, a program under which the State can modify monitoring 
requirements for consecutive systems. These modifications must not 
undermine public health protection and all systems, including 
consecutive systems, must comply with the TTHM and HAA5 MCLs based on 
the LRAA. However, such a program would allow the State to establish 
monitoring requirements that account for complicated distribution 
system relationships, such as where neighboring systems buy from and 
sell to each other regularly throughout the year, water passes through 
multiple consecutive systems before it reaches a user, or a large group 
of interconnected systems have a complicated combined distribution 
system. EPA intends to develop a guidance manual to address development 
of a State program and other consecutive system issues.
2. How Was This Proposal Developed?
    The practice of public water systems buying and selling water to 
each other has been commonplace for many years. Reasons include saving 
money on pumping, treatment, equipment, and personnel; assuring an 
adequate supply during peak demand periods; acquiring emergency 
supplies; selling surplus supplies; delivering a better product to 
consumers; and meeting Federal and State water quality standards. EPA 
estimates that there are at least 8500 consecutive systems nationally, 
based on the definitions being proposed today.
    Consecutive systems face particular challenges in providing water 
that meets regulatory standards for contaminants that can increase in 
the distribution system. Examples of such contaminants include 
coliforms, which can grow if favorable conditions exist, and some DBPs, 
including THMs and HAAs, which can increase when a disinfectant and DBP 
precursors continue to react in the distribution system.
    EPA is proposing requirements specifically for consecutive systems 
because States have taken widely varying approaches to regulating DBPs 
in consecutive systems. For example, some States do not regulate DBP 
levels in consecutive systems that deliver disinfected water but do not 
add a disinfectant. Other States determine compliance with DBP 
standards based on the combined distribution system that includes both 
the wholesaler and consecutive systems. In this case, sites in 
consecutive systems are treated as monitoring sites within the combined 
distribution system. Once fully implemented, this proposed rule will 
ensure similar protection for consumers in consecutive systems.
    EPA is proposing that consecutive systems and wholesale systems be 
on the same compliance schedule because generally the most cost-
effective way to achieve compliance with TTHM and HAA5 MCLs is to treat 
at the source, typically through precursor removal or alternative 
disinfectants. For a wholesale system to make the best decisions 
concerning the treatment steps necessary to meet TTHM and HAA5 LRAAs 
under the Stage 2 DBPR, both in its own distribution system and in the 
distribution systems of consecutive systems it serves, the wholesale 
system must know the DBP levels throughout the combined distribution 
system. Without this information, the wholesale system may design 
treatment changes that allow the wholesale system to achieve 
compliance, but leave the consecutive system out of compliance. EPA 
also recognizes that there may be cases where a consecutive system 
needs to add treatment even after a wholesale system has optimized its 
own treatment train.
    In consideration of these issues, the Stage 2 M-DBP Advisory 
Committee recognized two principles related to consecutive systems: (1) 
Consumers in consecutive systems should be just as well protected as 
customers of all systems, and (2) monitoring provisions should be 
tailored to meet the first principle. Accordingly, the Advisory 
Committee recommended that all wholesale and consecutive systems comply 
with provisions of the Stage 2 DBPR on the same schedule required of 
the wholesale or consecutive system serving the largest population in 
the combined distribution system. In addition, the Advisory Committee 
recommended that EPA solicit comments on issues related to consecutive 
systems that the Advisory Committee had not fully explored (USEPA 
2000g). EPA agrees with these recommendations and they are reflected in 
today's proposal.
3. Request for Comment
    EPA requests comment on all consecutive system issues related to 
this rule. Specifically, EPA requests comment on the following:

--Whether the proposed definitions adequately address various wholesale 
system-consecutive system relationships and issues.
--Whether any additional terms need to be defined and, if so, what the 
definition should be.
--Whether the criteria for States' use of the special primacy criteria 
and other State responsibilities are appropriate and adequate.
--Whether it is necessary to require that consecutive system treatment 
be installed on the same compliance schedule as the wholesale system in 
cases where the size of the consecutive system might otherwise allow it 
a longer compliance time frame and the consecutive system treatment 
does not affect water quality in any other system.

D. MCLs for TTHM and HAA5

1. What Is EPA Proposing Today?
    Today, EPA is proposing use of locational running annual averages 
(LRAAs) to determine compliance with the MCLs for TTHM and HAA5. 
Consistent with the Stage 2 M-DBP Advisory Committee recommendation, 
EPA is proposing a phased approach for LRAA implementation to allow 
systems to identify compliance monitoring locations for Stage 2B while 
facilitating transition to the new compliance strategy and maintaining 
simultaneous compliance schedules for the Stage 2 DBPR and the 
LT2ESWTR.
    In Stage 2A, all systems must comply with MCLs of 0.120 mg/L for 
TTHM and 0.100 mg/L for HAA5 as LRAAs using Stage 1 DBPR compliance 
monitoring sites. In addition, during this time period, all systems 
must continue to comply with the Stage 1 DBPR MCLs of 0.080 mg/L TTHM 
and 0.060 mg/L HAA5 as RAAs.
    In Stage 2B, all systems, including consecutive systems, must 
comply with MCLs of 0.080 mg/L TTHM and 0.060 mg/L HAA5 as LRAAs using 
sampling sites identified under the Initial Distribution System 
Evaluation (IDSE) (discussed in section V.H.).
    Details of proposed monitoring requirements and compliance 
schedules are discussed in preamble sections V.I. and V.J., 
respectively, and may be found in Sec.  141.136 and subpart V of 
today's rule.
2. How Was This Proposal Developed?
    a. Definition of an LRAA. The primary objective of the LRAA is to 
reduce exposure to high DBP levels. For an LRAA, an annual average must 
be computed at each monitoring site. The RAA compliance basis of the 
1979 TTHM rule and the Stage 1 DBPR allows a system-wide annual average 
under which high DBP concentrations in one or more locations are 
averaged with, and

[[Page 49585]]

dampened by, lower concentrations elsewhere in the distribution system. 
Figure V-1 illustrates the difference in calculating compliance with 
the MCLs for TTHM between a Stage 1 DBPR RAA, and the proposed Stage 2 
DBPR LRAA.
BILLING CODE 6560-50-P
[GRAPHIC] [TIFF OMITTED] TP18AU03.008

BILLING CODE 6560-50-P

[[Page 49586]]

    b. Consideration of regulatory alternatives. This section will 
discuss EPA's and the Stage 2 M-DBP Advisory Committee's decision-
making process as an array of alternative MCL strategies were 
considered. EPA believes that the MCL alternative proposed today (MCLs 
of 0.080 mg/L TTHM, 0.060 mg/L HAA5 as LRAAs) is supported by the best 
available research, data, and analysis. The science related to cancer 
and reproductive and developmental health effects that may be 
associated with DBPs, in conjunction with occurrence data that show 
that a significant number of high DBP levels occur under current 
regulatory scenarios, justify a change in regulation. EPA believes that 
this proposal achieves an appropriate balance between the available 
science and the uncertainties. EPA believes that regulatory action is 
necessary and prudent in the interest of further public health 
protection and that the LRAA alternative in combination with the IDSE 
is a balanced and reasonable approach. Although it will not remove all 
DBP peaks (individual samples with values greater than the MCL), this 
proposed regulation will ensure that DBP exposures across a system's 
distribution system are further reduced, are more equitable, and may 
reduce cancer and reproductive and developmental risk.
    The Advisory Committee discussions primarily focused on the 
relative magnitude of exposure reduction versus the expected impact on 
the water industry and its customers. Initially, this analysis compared 
expected reductions in DBP levels and predictions of treatment 
technology changes associated with a wide variety of Stage 2 DBPR MCL 
alternatives.
    After initial discussions, EPA and the Advisory Committee primarily 
focused on four types of alternative rule scenarios.

Preferred Alternative.--MCLs of 0.080 mg/L TTHM and 0.060 mg/L HAA5 as 
LRAAs. Bromate MCL of 0.010 mg/L.
Alternative 1.--MCLs of 0.080 mg/L TTHM and 0.060 mg/L HAA5 as LRAAs. 
Bromate MCL of 0.005 mg/L.
Alternative 2.--MCLs of 0.080 mg/L TTHM and 0.060 mg/L HAA5 as 
individual sample maximums (i.e., no single sample could exceed the 
MCL). Bromate MCL of 0.010 mg/L.
Alternative 3.--MCLs of 0.040 mg/L TTHM and 0.030 mg/L HAA5 as RAAs. 
Bromate MCL of 0.010 mg/L.

    EPA and the Advisory Committee, with assistance from the Technical 
Workgroup, conducted an in-depth analysis of these regulatory 
alternatives. In the process of evaluating alternatives, EPA and the 
Advisory Committee reviewed vast quantities of data and many analyses 
that addressed health effects, DBP occurrence, predicted reductions in 
DBP levels, predicted technology changes, and capital, annual, and 
household costs. Details of the compliance, occurrence, and cost 
forecasts for the four alternative rule scenarios are described in the 
Stage 2 DBPR Economic Analysis (EA) (USEPA 2003i) and the Stage 2 DBPR 
Occurrence Document (USEPA 2003o).
    In the end, the Advisory Committee recommended the Preferred 
Alternative in combination with the IDSE which they believed would 
reduce exposure to high levels of DBPs. Today, EPA is proposing the 
Preferred Alternative in combination with the IDSE.
    The only difference between the Preferred Alternative and 
Alternative 1 is the bromate MCL. The Advisory Committee's 
recommendation to maintain the Stage 1 DBPR bromate MCL of 0.010 mg/L 
is discussed in section V.G. of today's proposal.
    Alternatives 2 and 3 are significantly more stringent than the 
Stage 1 DBPR with respect to the TTHM and HAA5 requirements. 
Alternative 2 would require that all samples be below the MCL. Because 
DBP occurrence is variable across the distribution system and over time 
(as discussed in section IV), systems would have to base their 
disinfectant and treatment strategies on controlling their highest DBP 
occurrence levels. Alternative 3 maintains the Stage 1 DBPR RAA 
compliance calculation, but reduces the Stage 1 DBPR MCLs by 50 
percent. Both alternatives 2 and 3 would cause significant changes in 
treatment for a large number of systems. The estimated costs for 
Alternatives 2 and 3 are approximately an order of magnitude above the 
costs for the Preferred Alternative (see section VII.B.).
    Consistent with this greater stringency of alternatives 2 and 3, 
the predicted DBP reductions and the resulting health benefits for them 
are greater than those predicted for the Preferred Alternative. 
Although all members of the Advisory Committee believed that the 
science showing reproductive and developmental health effects that have 
been associated with DBPs was sufficient to cause concern and warrant 
regulatory action, the Advisory Committee did not believe that the 
association was certain enough to justify the substantial change in 
treatment technologies that would be required to meet these 
alternatives. Thus, the Advisory Committee rejected Alternatives 2 and 
3.
    c. Basis for the LRAA. This section discusses the data and 
information EPA used to determine that the LRAA is an appropriate 
compliance strategy for today's proposed rule. EPA has chosen 
compliance based on an LRAA due to concerns about levels of DBPs above 
the MCL in some portions of the distribution system. The LRAA standard 
will eliminate system-wide averaging. The individuals served in areas 
of the distribution system with above average DBP occurrence levels 
masked by averaging under an RAA are not receiving the same level of 
health protection. Although an LRAA standard still allows averaging at 
a single location over an annual period, EPA believes that changing the 
basis of compliance from an RAA to an LRAA will result in decreased 
exposure to above average DBP levels (see section VII.A. for 
predictions of DBP reductions under the LRAA MCLs). This conclusion is 
based on three considerations:
    (1) There is considerable evidence that under the current RAA MCL 
compliance monitoring requirements a small but significant proportion 
of monitoring locations experience high DBP levels. As summarized in 
section IV of this preamble, 14 and 21% of Information Collection Rule 
systems currently meeting the Stage 1 DBPR RAA MCLs had TTHM and HAA5 
single sample concentrations greater than the Stage 1 MCLs and ranged 
up to 140 [mu]g/L and 130 [mu]g/L respectively (Figures IV-1 and IV-2), 
though most of these exceedences were below 100 [mu]g/L.
    (2) In some situations, the populations served by certain portions 
of the distribution system consistently receive water that exceeds the 
MCL even though the system is in compliance. As discussed in section IV 
of this preamble, some Information Collection Rule systems meeting the 
Stage 1 DBPR RAA MCLs had monitoring locations that exceeded 0.080 mg/L 
TTHM and/or 0.060 mg/L HAA5 as an annual average (i.e., as LRAAs) by up 
to 25% (Figures IV-3 and IV-4). Five percent of plants that achieved 
compliance with the Stage 1 TTHM MCL of 0.080 mg/L based on an RAA had 
a particular sampling location that exceeded 0.080 mg/L as an LRAA 
(Figure IV-3). Figure IV-4 shows similar results based on Information 
Collection Rule HAA5 data. Three percent of plants that met the Stage 1 
HAA5 MCL of 0.060 mg/L as an RAA had a sampling location that exceeded 
0.060 mg/L as an LRAA. Customers served at these locations consistently 
received water with TTHM and/or HAA5 concentrations higher than the 
system-wide MCL.

[[Page 49587]]

    (3) Compliance based on an LRAA will remove the opportunity for 
systems to average out samples from high and low quality water sources. 
Some systems are able to comply with an RAA MCL even if they have a 
plant with a poor quality water source (that thus produces high 
concentrations of DBPs) because they have another plant that has a 
better quality water source (and thus lower concentrations of DBPs). 
Individuals served by the plant with the poor quality source will 
usually have higher DBP exposure than individuals served by the other 
plant.
    d. Basis for phasing LRAA compliance. EPA believes that a phased 
approach for LRAA implementation will facilitate transition to the new 
compliance requirements. Stage 2A of this proposed rule does not 
require systems to conduct any additional monitoring. They will 
continue to monitor at Stage 1 DBPR locations. Because the LRAA 
calculation is the same as the RAA calculation if there is only one 
site, Stage 2A compliance only applies to systems that monitor at more 
than one site and will only affect medium and large surface water 
systems (serving at least 10,000 people) or systems with multiple 
plants. Thus, the majority of ground water systems, small surface water 
systems, and some consecutive systems are not affected by the proposed 
Stage 2A requirements.
    e. TTHM and HAA5 as Indicators. In part, both the TTHM and HAA5 
classes are regulated because they occur at high levels and represent 
chlorination byproducts that are produced from source waters with a 
wide range of water quality. The combination of TTHM and HAA5 represent 
a wide variety of compounds resulting from bromine substitution and 
chlorine substitution reactions (i.e., bromoform has 3 bromines, TCAA 
has 3 chlorines, BDCM has one bromine and two chlorines, etc). EPA 
believes that the TTHM and HAA5 classes serve as an indicator for 
unidentified and unregulated DBPs. EPA believes that controlling the 
occurrence levels of TTHM and HAA5 will control the levels of all 
chlorination DBPs to some extent.
3. Request for Comment
    EPA requests comment on the alternative MCL strategies that were 
considered by the Advisory Committee and the determination to propose 
the Preferred Alternative in combination with the IDSE as the preferred 
regulatory strategy. EPA also requests comment on whether the proposed 
approach will reduce peak DBP levels.
    EPA requests comment on the phased MCL strategy and whether or not 
it will facilitate compliance with the LRAA. EPA also requests comment 
on the Stage 2A MCLs of 0.120 mg/L TTHM and 0.100 mg/L HAA5 as LRAAs 
and on the long-term MCLs of 0.080 mg/L TTHM and 0.060 mg/L HAA5 as 
LRAAs.

E. Requirements for Peak TTHM and HAA5 Levels

1. What Is EPA Proposing Today?
    Today, EPA is proposing that, concurrent with Stage 2B, systems 
must specifically document occurrences of peak DBP levels, termed 
significant excursions. In support of this provision, EPA is proposing 
that States, as a special primacy condition, develop criteria for 
determining whether a system has a significant excursion. EPA has 
developed draft guidance for systems and States on how systems may 
determine whether they have significant excursions. EPA is also 
proposing that a system that has a significant excursion must: (1) 
Evaluate distribution system operational practices to identify 
opportunities to reduce DBP levels (such as tank management to reduce 
residence time and flushing programs to reduce disinfectant demand), 
(2) prepare a written report of the evaluation, and (3) no later than 
the next sanitary survey, review the evaluation with their State. This 
review will take place under the sanitary survey components calling for 
the State to review monitoring, reporting, and data verification and 
system management and operation.
2. How Was This Proposal Developed?
    Because individual measurements from a location are averaged over a 
four-quarter period to determine compliance, there may be occurrence 
levels that exceed the MCL even when a system is in compliance with an 
LRAA MCL. EPA and the Advisory Committee were concerned about these 
exposures to peak levels of DBPs and the possible risk they might pose. 
This concern was clearly reflected in the Agreement in Principle, which 
states,
    ``Recognizing that significant excursions of DBP levels will 
sometimes occur, even when systems are in full compliance with the 
enforceable MCL, public water systems that have significant excursions 
during peak periods are to refer to EPA guidance on how to conduct peak 
excursion evaluations, and how to reduce such peaks. Such excursions 
will be reviewed as part of the sanitary survey process. EPA guidance 
on DBP level excursions will be issued prior to promulgation of the 
final rule and will be developed in consultation with stakeholders.''
    In evaluating this recommendation, EPA believes that the Advisory 
Committee's intent was clear with regard to the need for guidance on 
how to evaluate and reduce significant excursions. However, the 
Agreement is less clear on how, and where, to define what constitutes a 
significant excursion, and how to define the scope of the evaluation. 
EPA draft guidance recommends several approaches for determining 
whether significant excursions have occurred. While today's proposal 
requires an evaluation only of distribution system operational 
practices, EPA believes that many systems would benefit from a broader 
evaluation that includes treatment plant and other system operations.
    EPA recognizes that different stakeholders have different points of 
view on whether specific criteria that initiate the evaluation of 
significant excursions should be included in the rule or in guidance. 
EPA also recognizes that different stakeholders may have different 
perspectives on how to identify a significant excursion. For this 
proposal, EPA has prepared draft guidance for systems and States on how 
to (1) determine whether a significant excursion has occurred, using 
several different options, (2) conduct significant excursion 
evaluations, and (3) reduce significant excursion occurrence.
3. Request for Comment
    EPA requests comment on the proposed approach for addressing 
significant excursions and on the draft guidance. Is a special primacy 
condition the appropriate means for allowing flexibility in identifying 
significant excursions while ensuring that such evaluations occur? Is 
the sanitary survey the appropriate mechanism for reviewing significant 
excursion data with the State? Should a system be required to take 
corrective action when significant excursions occur? Should the 
required scope of the evaluation be expanded beyond distribution system 
operations?
    EPA also requests comment on whether specific criteria that 
initiate the evaluation of significant excursions should be included in 
the rule or in guidance. EPA requests comment on how to identify 
significant excursions (regardless of whether the criteria are in the 
rule or in guidance). For example, should the significant excursion be 
based on an individual measurement, e.g., any measurement being 25 or 
50% over either the TTHM or HAA5 MCLs? Alternatively, should the 
determination of a significant excursion be based on a certain level of 
variability among multiple measurements? For example,

[[Page 49588]]

should the significant excursion be based on the standard deviation of 
the LRAA exceeding specific numerical values for either TTHM (e.g., 
0.020 mg/l) or HAA5 (e.g., 0.015 mg/L)? Or should the excursion be 
based on a relative measure of variability (e.g., a relative standard 
deviation exceeding 25% or 50%) with the condition of a threshold 
average concentration also being exceeded (e.g., an LRAA needing to be 
at least 0.040 mg/l for TTHM or 0.030 mg/l for HAA5)? EPA requests 
comment on the above approaches or alternative approaches for 
determining whether a significant excursion has occurred. EPA also 
requests comment on whether different approaches may be appropriate for 
large and small systems.

F. BAT for TTHM and HAA5

1. What Is EPA Proposing Today?
    Today, EPA is proposing that the best available technology (BAT) 
for the TTHM and HAA5 LRAA MCLs (0.080 mg/L and 0.060 mg/L 
respectively) be one of the three following technologies:
    (1) GAC adsorbers with at least 10 minutes of empty bed contact 
time and an annual average reactivation/replacement frequency no 
greater than 120 days, plus enhanced coagulation or enhanced softening.
    (2) GAC adsorbers with at least 20 minutes of empty bed contact 
time and an annual average reactivation/replacement frequency no 
greater than 240 days.
    (3) Nanofiltration (NF) using a membrane with a molecular weight 
cut off of 1000 Daltons or less (or demonstrated to reject at least 80% 
of the influent TOC concentration under typical operating conditions).
    EPA is proposing a different BAT for consecutive systems than for 
wholesale systems to meet the TTHM and HAA5 LRAA MCLs. The proposed 
consecutive system BAT is chloramination with management of hydraulic 
flow and storage to minimize residence time in the distribution system.
2. How Was This Proposal Developed?
    a. Basis for the BAT. The Safe Drinking Water Act directs EPA to 
specify BAT for use in achieving compliance with the MCL. Systems 
unable to meet the MCL after application of BAT can get a variance (see 
section V.L. for a discussion of variances). Systems are not required 
to use BAT in order to comply with the MCL. They can use other 
technologies as long as they meet all drinking water standards and are 
approved by the State.
    EPA examined BAT using two different methods: (1) EPA analyzed data 
from the Information Collection Rule treatment studies and (2) EPA used 
the Surface Water Analytical Tool (SWAT), a model developed to compare 
alternative regulatory strategies. Both analyses support the BAT 
options proposed today. The results of each analyses are presented in 
the following two sections.
    i. BAT analysis using the Information Collection Rule treatment 
studies. EPA analyzed data from the Information Collection Rule 
treatment studies (Information Collection Rule Treatment Study Database 
CD-ROM, Version 1.0, USEPA 2000m; Hooper and Allgeier 2002). The 
treatment studies were designed to evaluate the technical feasibility 
of using GAC and NF to remove DBP precursors prior to the addition of 
chlorine-based disinfectants. Systems were required to conduct an 
Information Collection Rule treatment study based on TOC levels in the 
source or finished water. Specifically, surface water plants with 
annual average source water TOC concentrations greater than 4 mg/L and 
ground water plants with annual average finished water TOC 
concentrations greater than 2 mg/L were required to conduct treatment 
studies. Thus, the plants required to conduct treatment studies 
generally had waters with organic DBP precursor levels that were 
significantly higher than the Information Collection Rule national 
plant medians of 2.7 mg/L for source water at surface water plants and 
0.2 mg/L for finished water at ground water plants (USEPA 2003o).
    Plants that conducted GAC studies typically evaluated performance 
at two empty bed contact times, 10 and 20 minutes, over a wide range of 
operational run times to evaluate the variable nature of TOC removal by 
GAC. This allowed GAC performance to be assessed with respect to empty 
bed contact time as well as reactivation/replacement frequency. Plants 
that conducted membrane treatment studies evaluated one or two 
nanofiltration membranes with molecular weight cutoffs less than 1000 
Daltons. Regardless of the technology evaluated, all treatment studies 
evaluated DBP formation in the effluent from the advanced process under 
simulated distribution system conditions representative of the average 
residence time and using free chlorine as the primary and residual 
disinfectant. (For more information on the Information Collection Rule 
treatment study requirements and testing protocols, see USEPA 1996 a 
and b.)
    Based on the treatment study results, GAC is effective for 
controlling DBP formation for waters with influent TOC concentrations 
below approximately 6 mg/L (based on the Information Collection Rule 
and NRWA data, over 90 percent of plants have average influent TOC 
levels below 6 mg/L (USEPA 2003o)). Of the plants that conducted an 
Information Collection Rule GAC treatment study, approximately 70% of 
the surface water plants studies could meet the 0.080 mg/L TTHM and 
0.060 mg/L HAA5 MCLs, with a 20% safety factor (i.e., 0.064 mg/L and 
0.048 mg/L, respectively) using GAC with 10 minutes of empty bed 
contact time and a 120 day reactivation frequency, and 78% of the 
plants could meet the MCLs with a 20% safety factor using GAC with 20 
minutes of empty bed contact time and a 240 day reactivation frequency. 
As discussed previously, the treatment studies were conducted at plants 
with poorer water quality than the national average. Therefore, EPA 
believes that much higher percentages of plants nationwide could meet 
the MCLs with the proposed GAC BATs.
    Among plants using GAC, larger systems would likely realize an 
economic benefit from on-site reactivation, which could allow them to 
use smaller, 10-minute empty bed contact time contactors with more 
frequent reactivation (i.e., 120 days or less). Most small systems 
would not find it economically advantageous to install on-site carbon 
reactivation facilities, and thus would opt for larger, 20-minute empty 
bed contact time contactors, with less frequent carbon replacement 
(i.e., 240 days or less).
    The proposed reactivation/replacement interval for the 20 minute 
contactor (i.e., 240 days) is double the reactivation/replacement 
interval for 10 minute contactor (i.e., 120 days). This is based on the 
assumption of a linear relationship between empty bed contact time and 
the reactivation interval (e.g., a doubling of the empty bed contact 
time will result in a doubling of the reactivation interval). The data 
from the Information Collection Rule treatment studies indicates that 
this linear relationship may not always hold and that doubling the 
empty bed contact time generally results in more than a doubling of the 
reactivation interval. While there may be some operational advantage in 
using larger empty bed contact times, the larger contactors will result 
in additional capital expenditures. Furthermore, the economic 
optimization of a GAC process must also consider the number of smaller 
contactors in parallel, since it may be advantageous to operate a 
larger number of smaller contactors in parallel, allowing each 
individual contactor to be

[[Page 49589]]

operated for a longer period of time. Based on these considerations, 
and the analysis of subject matter experts, it was concluded that the 
proposed combination of GAC empty bed contact times and reactivation/
replacement intervals were reasonable for BAT.
    The Information Collection Rule treatment study results also 
demonstrated that nanofiltration was the better DBP control technology 
for ground water sources with high TOC concentrations (i.e., above 
approximately 6 mg/L). The results of the membrane treatment studies 
showed that all ground water plants could meet the 0.080 mg/L TTHM and 
0.060 mg/L HAA5 MCLs, with a 20% safety factor (i.e., 0.064 mg/L and 
0.048 mg/L, respectively) at the average distribution system residence 
time using nanofiltration. Nanofiltration would be less expensive than 
GAC for high TOC ground waters, which generally require minimal 
pretreatment prior to the membrane process. Also, nanofiltration is an 
accepted technology for treatment of high TOC ground waters in Florida 
and parts of the Southwest, areas of the country with elevated TOC 
levels in ground waters.
    ii. BAT analysis using the SWAT. The second method that EPA used to 
examine alternatives for BAT was the SWAT model that was developed to 
compare alternative regulatory strategies. EPA modeled the following 
BAT options: enhanced coagulation/softening with chlorine (the Stage 1 
DBPR BAT); enhanced coagulation/softening with chlorine and no 
predisinfection; enhanced coagulation and GAC10; enhanced coagulation 
and GAC20; and enhanced coagulation and chloramines. Enhanced 
coagulation/softening is required under the Stage 1 DBPR at subpart H 
conventional filtration plants. In the model, GAC10 was defined as 
granular activated carbon with an empty bed contact time of 10 minutes 
and a reactivation or replacement interval of 90 days or longer. GAC20 
was defined as granular activated carbon with an empty bed contact time 
of 20 minutes and a reactivation or replacement interval of 90 days or 
longer. EPA assumed that systems would be operating to achieve both the 
Stage 2B MCLs of 0.080 mg/L TTHM and 0.060 mg/L HAA5 as an LRAA and the 
SWTR removal and inactivation requirements of 3-log for Giardia and 4-
log for viruses. EPA also evaluated the BAT options under the 
assumption that plants operate to achieve DBP levels 20% below the MCL 
(safety factor). These assumptions along with other inputs for the SWAT 
runs are consistent with those used in the Economic Analysis of today's 
proposed rule (USEPA 2003i).
    The compliance percentages forecasted by the SWAT model are 
indicated in Table V-1. EPA estimates that more than 97% of large 
systems will be able to achieve the Stage 2B MCLs regardless of post-
disinfection choice if they were to apply one of the proposed GAC BATs, 
i.e., enhanced coagulation (EC) and GAC10 (Seidel Memo, 2001). As shown 
in the Stage 2 DBPR Occurrence document (USEPA 2003o), the source water 
quality (e.g., DBP precursor levels) in medium and small systems is 
expected to be comparable to or better than that for the large systems. 
Based on the large system estimate, EPA believes it is conservative to 
assume that at least 90% of medium and small systems will be able to 
achieve the Stage 2B MCLs if they were to apply one of the proposed GAC 
BATs. EPA assumes that small systems may adopt GAC20 in a replacement 
mode (with replacement every 240 days) over GAC10 because it may not be 
economically feasible for some small systems to install and operate an 
on-site GAC reactivation facility. Moreover, some small systems may 
find nanofiltration cheaper than the GAC20 in a replacement mode if 
their specific geographic locations cause a relatively high cost for 
routine GAC shipment.

  Table V-1.--SWAT Model Predictions of Percent of Large Plants in Compliance With TTHM and HAA5 Stage 2B MCLs After Application of Specified Treatment
                                                                      Technologies
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Compliance with 0.080 mg/L (TTHM)/0.060 mg/L       Compliance with 0.064 mg/L (TTHM)/0.048 mg/L
                                                                       (HAA5) LRAAs                        (HAA5) LRAAs (MCLs with 20% safety factor)
                                                   -----------------------------------------------------------------------------------------------------
                   Technology *                           Residual disinfectant                              Residual disinfectant
                                                   ----------------------------------   All systems   ----------------------------------   All systems
                                                        Chlorine        Chloramine                         Chlorine        Chloramine
--------------------------------------------------------------------------------------------------------------------------------------------------------
Enhanced Coagulation (EC).........................             73.5             76.9             74.8             57.2             65.4             60.4
EC (no predisinfection)...........................             73.4             88.0             78.4             44.1             62.7             50.5
EC & GAC10........................................            100               97.1             99.1            100               95.7             98.6
EC & GAC20........................................            100              100              100              100              100              100
EC & All Chloramines..............................             NA               83.9             NA               NA               73.6            NA
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Enhanced coagulation/softening is required under the Stage 1 DBPR for conventional plants.

    b. Basis for the Consecutive System BAT. EPA believes that the best 
compliance strategy for consecutive systems is to collaborate with 
wholesalers on the water quality they need. For consecutive systems 
that are having difficulty meeting the MCLs, EPA is proposing a BAT of 
chloramination with management of hydraulic flow and storage to 
minimize residence time in the distribution system. EPA is proposing a 
different BAT than for wholesale systems because a consecutive system's 
source water has already been disinfected and contains DBPs that cannot 
be effectively removed or controlled with the BATs proposed for 
wholesale systems. EPA believes the proposed consecutive system BAT is 
an effective means for consecutive systems to meet the MCLs.
    Chloramination has been used for residual disinfection for many 
years to minimize the formation of chlorination DBPs, including TTHM 
and HAA5 (Stage 2 Technology and Cost Document, USEPA 2003k). The BAT 
provision to manage hydraulic flow and minimize residence time in the 
distribution system is to facilitate the maintenance of the chloramine 
residual and minimize the likelihood for nitrification. Nitrification, 
the process by which microbes convert free ammonia to nitrate and 
nitrite, is a concern for systems using chloramines. Nitrification, 
however, can be controlled with appropriate chlorine to ammonia ratios, 
increasing flow in low demand areas, and increasing storage tank 
turnover. EPA proposes that systems implementing the consecutive system 
BAT must do the following: (1) Maintain a chloramine residual 
throughout the distribution system, (2) develop and submit a plan that 
indicates actions that will be taken to minimize the residence time of 
water

[[Page 49590]]

within the distribution system, (3) have the plan approved by the 
Primacy Agency, and (4) implement the plan as approved by the Primacy 
Agency. Minimum components of the management plan would include 
periodic scheduled flushing of all dead end pipes and storage vessels 
through which water is delivered to customers, and hydraulic flow 
control procedures that routinely circulate water in all storage 
vessels within the distribution system.
    EPA believes that the BATs proposed for wholesale systems are not 
appropriate for consecutive systems because each of these BATs, when 
applied to water with DBPs, raises other concerns. GAC is not cost-
effective for removing DBPs. In addition, dioxin, a carcinogen, may be 
formed during GAC regeneration if GAC has been used to adsorb 
chlorinated DBPs. Nanofiltration is only moderately effective at 
removing THMs or HAAs if membranes that have a very low molecular 
weight cutoff and very high cost of operation are employed. Therefore, 
GAC and nanofiltration are not appropriate BATs for consecutive 
systems.
3. Request for Comment
    EPA requests comment on the proposed BATs including the BAT for 
consecutive systems.

G. MCL, BAT, and Monitoring for Bromate

1. What Is EPA Proposing Today?
    EPA is proposing today that the MCL for bromate for systems using 
ozone remain at 0.010 mg/L as an RAA for samples taken at the entrance 
to the distribution system as established by the Stage 1 DBPR and as 
provided for under the risk-balancing provisions of section 1412(b)(5) 
of the SDWA. EPA's proposal is consistent with the recommendation of 
the Stage 2 M-DBP Advisory Committee, which considered the potential 
that reducing the bromate MCL could both increase the concentration of 
other DBPs in the drinking water and interfere with the efficacy of 
microbial pathogen inactivation. In addition, as required by the SDWA 
and as recommended by the Advisory Committee, EPA will review the 
bromate MCL as part of the 6-year review process and determine whether 
the MCL should remain at 0.010 mg/L or be reduced to a lower level. As 
a part of that review, EPA will consider the increased utilization of 
alternative technologies, such as UV, and whether the risk/risk 
concerns reflected in today's proposal remain valid.
    Because EPA is not revising the Stage 1 DBPR bromate MCL, EPA is 
not proposing a revised BAT for bromate. The Stage 1 DBPR BAT for 
bromate is defined as control of ozone treatment processes to reduce 
production of bromate. EPA also determined that it was not necessary to 
regulate bromate in non-ozone systems that use hypochlorite.
    Finally, EPA is proposing to modify the criterion for a system that 
uses ozone (and therefore must monitor for bromate) to qualify for 
reduced bromate monitoring from one sample per ozone plant per month to 
one sample per plant per quarter.
2. How Was This Proposal Developed?
    a. Bromate MCL. Bromate is a principal byproduct from ozonation of 
bromide-containing source waters. As described in more detail later, 
making the bromate MCL more stringent has the potential to decrease 
current levels of microbial protection, impair the ability of systems 
to control resistant pathogens like Cryptosporidium, and increase 
levels of DBPs from other disinfectants that may be used instead of 
ozone.
    EPA estimates that the 1 in 10,000 excess lifetime cancer risk 
level for bromate is 0.005 mg/L. EPA proposed and ultimately finalized 
an MCL of 0.010 mg/L in the Stage 1 DBPR, primarily because available 
analytical detection methods for bromate could only reliably measure to 
0.01 mg/L (USEPA 1994b). Analytical methods for bromate are now 
available to quantify bromate concentrations as low as 0.001 mg/L. Due 
to the availability of lower detection methods for bromate, as part of 
the Stage 2 M-DBP Advisory Committee deliberations, EPA considered 
revising the MCL to 0.005 mg/L or lower.
    As a disinfectant, ozone is highly effective against a broad range 
of microbial pathogens including bacteria, viruses, and protozoa. 
Moreover, ozone is one of the few disinfectants available in water 
treatment that is capable of inactivating Cryptosporidium, a protozoan 
which can cause severe intestinal disorders and can be deadly to those 
with compromised immune systems. The oxidizing properties of ozone are 
also valuable for treatment objectives like control of tastes and odors 
and removal of iron and manganese. In contrast, chlorine, the most 
common disinfectant and oxidant in water treatment, is substantially 
less effective for controlling Cryptosporidium. Chlorine dioxide, while 
capable of providing low levels of inactivation for Cryptosporidium, 
typically cannot be used at high doses without violating the MCL for 
chlorite, a byproduct of chlorine dioxide. UV light is highly effective 
against Cryptosporidium and Giardia and most viruses, but has not been 
used extensively to treat drinking water in the United States.
    As of early 2000, there were 332 plants of various sizes using 
ozone (Overbeck 2000) and 58 plants that were planning to install 
ozonation (Rice 2000--personal communication: email 7/14/2000). A 
significant percent of current ozone plants use ozone for some portion 
of their disinfection objective (Rice, 2000--personal communication: 
email 7/14/2000). An ozone system that could not meet a 0.005 mg/L 
bromate MCL would have three primary options: decrease the ozone dose; 
switch to a different disinfectant; or install an advanced filtration 
process such as membranes, sometimes in combination with the first two 
options. Of these three options, the third is likely effective but very 
expensive, while the first two create the risk either of reducing 
microbial protection for a wide range of microbial pathogens, or of 
increasing formation of DBPs other than bromate.
    In an attempt to achieve a lower level of bromate, some systems 
might be driven to reduce the applied ozone dose to the minimum 
necessary for regulatory compliance or switch to other treatment 
processes. Many systems currently achieve more disinfection than is 
required by the SWTR and if a system were to simply lower the ozone 
dose, protection from pathogens may be compromised. In addition, since 
inactivation of Cryptosporidium requires much higher ozone doses than 
Giardia inactivation, systems cannot achieve Cryptosporidium 
inactivation with low ozone doses.
    If a system were to lower the ozone dose and supplement with an 
additional disinfectant, or switch entirely to a different 
disinfectant, the system may not achieve the same level of microbial 
protection as is afforded by ozonation. Also, other potentially harmful 
byproducts from the different disinfectant would be produced.
    During the Stage 2 M-DBP Advisory Committee discussions, the TWG 
evaluated the impact of reducing the bromate MCL from 0.010 mg/L to 
0.005 mg/L as an annual average. The TWG concluded that many systems 
currently using ozone or predicted to install ozone to inactivate 
microbial pathogens would have significant difficulty maintaining 
bromate levels at or below 0.005 mg/L. In the Information Collection 
Rule survey of systems serving greater than 100,000 people, all of the 
ozone plants had annual average

[[Page 49591]]

bromate concentrations below the 0.010 mg/L level (USEPA 2003o). 
However, approximately 20% of these ozone plants did not meet the 0.005 
mg/L level. Using the assumption that systems operate their plants 
using a safety margin of 20% below the MCL, about 30% of ozone plants 
did not reliably attain this level (0.004 mg/L). During the Information 
Collection Rule, for the first half of 1998, much of the U.S. was 
wetter than normal (NOAA 1998). This hydrogeological condition often 
leads to lower than normal bromide concentrations due to dilution by 
higher water flows. In the second half of 1998, California continued to 
experience El Nino rains (40% of Information Collection Rule ozone 
plants were located in California) but many other areas of the country 
such as Texas and Florida experienced a drought. The percentage of 
ozone systems unable to achieve 0.005 mg/L bromate would likely 
increase during years in which bromide concentrations in California 
were elevated as consequence of drought.
    The ability of systems to use ozone to meet Cryptosporidium 
treatment requirements proposed under the LT2ESWTR would be diminished 
if the bromate MCL was decreased from 0.010 to 0.005 mg/L. The proposed 
LT2ESWTR will require a subset of systems, based on source water 
pathogen levels, to provide from 1.0 to 2.5 logs of additional 
treatment for Cryptosporidium. Ozone doses required to inactivate 
Cryptosporidium are substantially greater than those required for 
Giardia and viruses. To assess the potential impact of a lower bromate 
MCL on the ability of systems to treat for Cryptosporidium, the TWG 
estimated the percentage of treatment plants that could use ozone to 
inactivate from 0.5 to 2.5 log of Cryptosporidium without exceeding a 
bromate MCL of either 0.005 or 0.010 mg/L (USEPA 2003i). These 
estimations were based on analyses of Information Collection Rule 
source water quality data, coupled with projected ozone dose 
requirements for Cryptosporidium. This analysis suggests that 88% of 
systems could use ozone to achieve 1 log of Cryptosporidium 
inactivation and 47% could inactivate 2 log while complying with a 
bromate MCL of 0.010 mg/L. With the bromate MCL reduced to 0.005 mg/L, 
though, these estimates drop to 67% of systems able to inactivate 1 log 
of Cryptosporidium with ozone and only 14% able to inactivate 2 log. 
The number of plants predicted to be able to treat for Cryptosporidium 
with ozone and meet a 0.005 mg/L standard was further reduced when 
periods of higher bromide levels, similar to drought conditions, were 
modeled. This trend is further exacerbated since the proposed LT2ESWTR 
would require more stringent ozone operating conditions (such as higher 
ozone doses and longer contact times) than under current surface water 
treatment requirements for the subset of plants with higher 
Cryptosporidium concentrations in their source water and would thus 
result in higher bromate formation than assumed by the TWG. Thus, as 
systems are required to meet more stringent inactivation requirements, 
a large number of systems would be forced to select treatment processes 
other than ozone if the bromate standard were lowered to 0.005 mg/L.
    The Stage 2 M-DBP Advisory Committee considered that reducing the 
bromate MCL to 0.005 mg/L could both increase the concentration of 
other DBPs in the drinking water and interfere with the efficacy of 
microbial pathogen inactivation. Therefore, the Advisory Committee 
recommended, for purposes of the Stage 2 DBPR, that the bromate MCL 
remain at 0.010 mg/L. EPA will review the bromate MCL as part of the 
ongoing 6-year review process and determine whether the MCL should 
remain at 0.010 mg/L or be reduced to a lower concentration based on 
new information.
    Today, EPA is proposing to leave the bromate MCL at 0.010 mg/L, 
consistent with the Advisory Committee's recommendation. EPA believes 
that this is a prudent step at this time, in order to preserve 
microbial protection. EPA will continue to analyze any new bromate 
health effects data as they become available. It is possible that EPA 
may determine that the bromate MCL should be decreased to 0.005 mg/L or 
lower in a future rulemaking.
    b. Bromate in hypochlorite solutions. The Stage 2 M-DBP Advisory 
Committee also discussed the issue of hypochlorite solutions 
contaminated with bromate. This contamination can occur during the 
production of hypochlorite solutions from natural salt deposits. The 
range of bromate concentrations in hypochlorite stock solutions varies 
widely (Bolyard et al. 1992; Chlorine Institute 1999, 2000). Moreover, 
the bromate contained in the stock solution is diluted upon addition to 
the drinking water. From data on Information Collection Rule ozone 
systems that used hypochlorite versus those that used gaseous chlorine, 
the TWG estimated that hypochlorite solutions contributed an average of 
0.001 mg/L bromate.
    The Advisory Committee discussed these results and, since the 
bromate level resulting from hypochlorite solutions was small compared 
to the MCL, did not recommend regulating bromate at systems not using 
ozone (non-ozone systems). The Advisory Committee recognized that ozone 
systems also using hypochlorite will have to be careful about the 
quality of their stock solution.
    c. Criterion for reduced bromate monitoring. Because more sensitive 
bromate methods are now available, EPA is proposing a new criterion for 
reduced bromate monitoring. In the Stage 1 DBPR, EPA required ozone 
systems to demonstrate that source water bromide levels, as a running 
annual average, did not exceed 0.05 mg/L. EPA elected to use bromide as 
a surrogate for bromate in determining eligibility for reduced 
monitoring because the available analytical method for bromate was not 
sensitive enough to quantify levels well below the bromate MCL of 0.010 
mg/L.
    In section V.O., EPA is proposing several new analytical methods 
for bromate that are far more sensitive than the existing method. Since 
these methods can measure bromate to levels of 0.001 mg/L or lower, EPA 
is proposing to replace the criterion for reduced bromate monitoring 
(source water bromide running annual average not to exceed 0.05 mg/L) 
with a bromate running annual average not to exceed 0.0025 mg/L.
    In the past, EPA has often set the criterion for reduced monitoring 
eligibility at 50% of the MCL, which would be 0.005 mg/L. However, as 
discussed before, EPA is proposing that the MCL for bromate remain at 
0.010 mg/L, a level that is higher than EPA's usual excess cancer risk 
range of 10(-4) to 10(-6) at 2x10(-4) because of risk tradeoff 
considerations. EPA believes that the decision for reduced monitoring 
is separate from these risk tradeoff considerations. Risk tradeoff 
considerations influence the selection of the MCL, while reduced 
monitoring requirements are designed to ensure that the MCL, once 
established, is reliably and consistently achieved. Requiring a running 
annual average of 0.0025 mg/L for the reduced monitoring criterion 
allows greater confidence that the system is achieving the MCL and thus 
ensuring public health protection.
3. Request for Comment
    EPA requests comment on the decision to maintain the Stage 1 DBPR 
bromate BAT and MCL of 0.010 mg/L. EPA also requests comment on the 
decision not to require bromate

[[Page 49592]]

monitoring at non-ozone systems that use hypochlorite.
    EPA requests comment on whether the criterion for reduced bromate 
monitoring should be set at a level other than 0.0025 mg/L, and a 
rationale for setting it at that level.

H. Initial Distribution System Evaluation (IDSE)

    The IDSE is an important part of today's proposed regulation that 
is intended to identify sample locations for Stage 2B compliance 
monitoring that represent distribution system sites with high DBP 
concentrations.
1. What is EPA Proposing Today?
    EPA is proposing a requirement for systems to perform an Initial 
Distribution System Evaluation (IDSE). Systems will collect data on DBP 
levels throughout their distribution system, evaluate these data to 
determine which sampling locations are most representative of high DBP 
levels and compile this information into a report for submission to the 
primacy agency.
    a. Applicability. All community water systems, and large 
nontransient noncommunity water systems (those serving at least 10,000 
people) that add a primary or residual disinfectant other than 
ultraviolet light, or that deliver water that has been treated with a 
primary or residual disinfectant other than ultraviolet light (i.e., 
consecutive systems) are required to conduct an IDSE under the proposed 
rule. The IDSE requirement for systems serving fewer than 500 people 
may be waived if the State determines that the monitoring site approved 
for Stage 1 DBPR compliance is sufficient to represent both high HAA5 
and high TTHM concentrations. The State must submit criteria for this 
waiver determination to EPA as part of their primacy application. 
States may decide to waive the IDSE requirement for all systems serving 
fewer than 500 or some subset of all systems serving fewer than 500 if 
the State determines that it is appropriate. EPA is developing an IDSE 
Guidance Manual that will include guidance to States on situations for 
which a waiver would be appropriate (USEPA 2003j).
    b. Data collection. IDSEs are intended to help identify and select 
Stage 2B compliance monitoring sites that represent high concentrations 
of TTHMs and HAA5. To be able to identify these sites, systems and 
States must have monitoring data collected from throughout their 
distribution systems. Therefore, under today's proposed rule, systems 
are required to collect monitoring data on the concentrations of these 
DBPs. There are three possible approaches by which a system can meet 
the IDSE requirement.
    i. Standard monitoring program. The standard monitoring program 
requires one year of monitoring on a specified schedule throughout the 
distribution system. The frequency and number of samples required under 
the standard monitoring program is determined by source water type, 
number of treatment plants, and system size (see section V.J. for a 
more detailed discussion of the specific monitoring requirements). 
Prior to commencing the standard monitoring program, systems must 
prepare a monitoring plan. EPA's IDSE Guidance Manual will provide 
guidance on selecting monitoring sites and conducting the standard 
monitoring program (USEPA 2003j). As recommended by the Advisory 
Committee, EPA is proposing that the standard monitoring program 
results are not to be used for determining compliance with MCLs and 
that systems will not be required to report IDSE results in the 
Consumer Confidence Report.
    ii. System specific study. Under this approach, systems may choose 
to perform a system-specific study based on earlier monitoring studies 
or other data analysis in lieu of the standard monitoring program. 
These studies must provide equivalent or better information than the 
standard monitoring program for selecting sites that represent high 
TTHM and HAA5 levels. Examples of alternative studies are: (1) Recent 
TTHM and HAA5 monitoring data that encompass a wide range of sample 
sites representative of the distribution system, including those judged 
to represent high TTHM and HAA5 concentrations and (2) hydraulic 
modeling studies that simulate water movement in the distribution 
system. Historical TTHM and HAA5 results submitted by systems must have 
been generated by certified laboratories and must include the system's 
most recent data. Treatment plant and distribution system 
characteristics at the time of historical data collection must reflect 
the current plant operations and distribution system. EPA's IDSE 
Guidance Manual will include a guidance for system-specific studies and 
how to determine whether site-specific data could be sufficient to meet 
the IDSE requirements (USEPA 2003j).
    iii. 40/30 certification. Under this approach, systems certify to 
their primacy agency that all required Stage 1 DBPR compliance samples 
were properly collected and analyzed during the two years prior to the 
start of the IDSE, and all individual compliance samples were <= 0.040 
mg/L for TTHM and <=0.030 mg/L for HAA5. Properly collected and 
analyzed compliance samples are those taken at required locations at 
times specified in the system's Stage 1 DBPR monitoring plan and 
analyzed by certified laboratories. Systems not required to collect 
Stage 1 DBPR compliance samples can not utilize the 40/30 certification 
approach because they do not have data to determine sampling locations 
that represent high concentrations of TTHMs and HAA5. Systems that 
qualify for reduced monitoring for the Stage 1 DBPR during the two 
years prior to the start of the IDSE, may use results of both routine 
and reduced Stage 1 DBPR monitoring to prepare the 40/30 certification. 
Large ground water systems may not have two years of HAA5 data to 
evaluate due to the timing of the Stage 1 DBPR and the IDSE 
requirements. EPA is proposing that, if two years worth of HAA5 data 
are not available, large ground water systems evaluate the most recent 
two years of TTHM data including data collected in accordance with the 
1979 TTHM rule and all available HAA5 compliance data collected up to 
nine months following promulgation of this rule when making the 40/30 
certification. Similarly, small wholesale and consecutive systems 
required to submit their IDSE report no later than two years after 
publication of the final rule will evaluate all available Stage 1 DBPR 
compliance data collected up to nine months following promulgation.
    c. Implementation. All systems subject to the IDSE requirement 
under the proposed rule (except those receiving a very small system 
waiver from the State) must submit a report to the primacy agency. The 
requirements for the report depend upon the IDSE data collection 
alternative that the system selects and are listed in Table V-2.

[[Page 49593]]



                  Table V-2.--IDSE Report Requirements
------------------------------------------------------------------------
     IDSE data collection
         alternative                    IDSE report requirements
------------------------------------------------------------------------
Standard Monitoring Program..  [sbull] All standard monitoring program
                                TTHM and HAA5 analytical results, the
                                original monitoring plan, and an
                                explanation of any deviations from that
                                plan.
                               [sbull] A schematic of the distribution
                                system.
                               [sbull] Recommendations and justification
                                for where and during what month(s) Stage
                                2B monitoring should be conducted.
System Specific Study........  [sbull] All studies, reports, analytical
                                results and modeling.
                               [sbull] A schematic of the distribution
                                system.
                               [sbull] Recommendations and justification
                                for where and during what month(s) Stage
                                2B monitoring should be conducted
40/30 Certification..........  [sbull] A certification that all required
                                compliance samples were properly
                                collected and analyzed during the two
                                years prior to the start of the IDSE and
                                all individual compliance samples were
                                <= 0.040 mg/L for TTHM and <=0.030 mg/L
                                for HAA5.
                               [sbull] Results of compliance samples
                                taken after the IDSE was scheduled to
                                begin and before the IDSE report was
                                submitted.
                               [sbull] Recommendations for where and
                                during what month(s) Stage 2B monitoring
                                should be conducted.
------------------------------------------------------------------------

    All IDSE reports must include recommendations for the location and 
schedule for the Stage 2B monitoring. The number of sampling locations 
and the criteria for their selection are described in Sec.  141.605 of 
today's proposed rule, and in section V.I. Generally, a system must 
recommend locations with the highest LRAAs unless it provides a 
rationale (such as ensuring geographical coverage of the distribution 
system instead of clustering all sites in a particular section of the 
distribution system) for selecting other locations. Systems must 
consider both their compliance data and IDSE data in making this 
determination. In addition to specifying a protocol for identifying 
recommended monitoring sites in the rule language, EPA will provide 
guidance for recommending compliance monitoring sites (including 
rationales for systems to recommend sites that do not have the highest 
LRAA concentrations) and preparing the IDSE report. EPA will also 
provide a process to address IDSE implementation issues during the 
period prior to State primacy. At the time that systems serving fewer 
than 10,000 people conduct their monitoring or analyze their site-
specific data, many States may have primacy.
    The compliance schedules for the IDSE and other requirements of the 
proposed rule are described in detail in section V.J. Systems serving 
at least 10,000 people (and those smaller wholesale and consecutive 
systems associated with larger systems) will be collecting data for 
their IDSE prior to State primacy. EPA intends to have an IDSE Guidance 
Manual available to assist systems in performing the IDSE (USEPA 
2003j). Primacy agencies will specify requirements for systems that do 
not submit an IDSE report, or that have not, in the determination of 
the primacy agency, conducted an adequate IDSE, in addition to giving 
the system a monitoring and reporting violation. These requirements may 
include repeating the IDSE while conducting compliance monitoring at 
Stage 1 monitoring sites or conducting Stage 2 compliance monitoring at 
sites selected by the State.
    Consecutive systems are subject to the IDSE requirements of today's 
proposed rule. IDSE requirements for consecutive systems are largely 
the same as for other systems, but with two differences. First, the 
schedule for completion of the IDSE by a consecutive system is 
dependent upon the population of the wholesale system. If a consecutive 
system serving fewer than 10,000 buys water from a system that serves 
10,000 or more people, then this consecutive system must comply within 
the same schedule as that for systems = 10,000. Conversely, 
if a wholesale system serves < 10,000 but sells water to a consecutive 
system serving = 10,000, then both the wholesale system and 
the consecutive system must complete the IDSE within the same schedule 
as that for systems = 10,000. The second difference for 
consecutive systems is that the procedure for recommending Stage 2B 
compliance monitoring locations is modified for consecutive systems 
purchasing or receiving all of their finished water from a wholesale 
system. These modified procedures are described in Sec.  141.605 of 
today's proposed rule, and in section V.I.
2. How Was This Pr oposal Developed?
    The IDSE was recommended by the Stage 2 M-DBP Advisory Committee. 
The Advisory Committee believed that maintaining Stage 1 DBPR sampling 
sites for the Stage 2 DBPR would not accomplish the objective of 
providing consistent and equitable protection across the distribution 
system.
    a. Applicability. The M-DBP Advisory Committee recommended that an 
IDSE be performed on all community systems to help to identify the 
locations in the distribution system that represent high DBP 
concentrations. EPA believes that large nontransient noncommunity water 
systems (those serving at least 10,000 people) also have distribution 
systems that require further evaluation to determine the most 
representative locations of high DBP levels. Therefore, large 
nontransient noncommunity systems and all community systems are 
required to perform an IDSE under today's proposal.
    States may waive the IDSE requirement for those very small systems 
(systems that serve fewer than 500 people) that monitor for Stage 1 
DBPR compliance at the maximum residence time site if the State 
determines their maximum residence time Stage 1 compliance monitoring 
site is likely to capture both the high TTHM and high HAA5 levels 
within the distribution system. The Advisory Committee recommended this 
waiver be included because many very small systems have small 
distribution systems and the high TTHM and high HAA5 site is at the 
same location. The Advisory Committee also recognized that not all very 
small systems have a single monitoring site that would represent both 
high TTHM and high HAA5 levels (e.g., some rural systems with large 
distribution systems) and thus did not recommend a blanket IDSE waiver 
for all very small systems.
    b. Data collection. The data collection requirements of the IDSE 
are designed to find both high TTHM and high HAA5 sites (see section 
V.I. for IDSE monitoring site locations). The IDSE is intended as a 
one-time requirement. High TTHM and HAA5 concentrations often occur at 
different locations in the

[[Page 49594]]

distribution system. The Stage 1 DBPR monitoring sites identified as 
the maximum location are selected according to residence time. Because 
HAAs can degrade in the distribution system in the absence of 
sufficient disinfectant residual (Baribeau et al. 2000), residence time 
alone is not an ideal criterion for identifying high HAA5 sites. The 
Information Collection Rule data show that of the four monitoring 
locations sampled per system, the one identified as the maximum 
residence time location was often not the location where the highest 
DBP levels were found. In fact, over 60 percent of the highest HAA5 
LRAAs and 50 percent of the highest TTHM LRAAs were found at sampling 
locations in the system other than the maximum residence time location 
(see section IV). Thus the method and assumptions used to select the 
Information Collection Rule monitoring sites, and the Stage 1 DBPR 
compliance monitoring sites, are not sufficiently reliable to select 
Stage 2 DBPR compliance monitoring sites that will capture high DBP 
levels.
    This data analysis reveals that a reevaluation of monitoring sites 
is necessary at many systems to capture sites with high DBP levels. The 
Advisory Committee recommended sample locations (based on distribution 
disinfectant type) at widely distributed sites (see section V.I. for 
details on IDSE monitoring requirements). Monitoring at additional 
sites across the distribution system increases the chance of finding 
sites with high DBP levels and targets both DBPs that degrade, and DBPs 
that form, as residence time increases in the distribution system. EPA 
believes that the required number of monitoring locations plus Stage 1 
monitoring results provides an adequate recharacterization of DBP 
levels throughout the distribution system, at a reasonable cost. With a 
recharacterization of distribution systems that focuses on both high 
TTHM and HAA5 occurrence, EPA believes that high occurrence sites will 
be better represented in this standard monitoring program. Systems will 
be required to take steps to address high DBP levels at points that 
might otherwise have gone undetected. EPA believes that the decrease in 
DBP exposure anticipated to result from the transition from an RAA to 
an LRAA will be augmented by the IDSE.
    The frequency and number of samples required for the standard 
monitoring program decrease as system size (population served) 
decreases and depend on source water type. The Advisory Committee 
believed that the number of samples required for large and medium 
surface water systems was not necessary for small surface water systems 
and ground water systems. The majority of small systems have 
distribution systems with simpler designs than large systems. DBP 
occurrence in ground water systems is generally lower and less variable 
than in surface water systems due to lower and less variable precursor 
levels and much less temperature variation (see section IV).
    Committee members recognized that some systems have detailed 
knowledge of their distribution systems by way of hydraulic modeling 
and/or ongoing widespread monitoring plans (well beyond that required 
for compliance monitoring) that would provide equivalent or superior 
monitoring site selection compared to IDSE monitoring. Therefore, the 
Advisory Committee recommended that such systems be allowed to 
determine new monitoring sites using system-specific data such as 
historical monitoring data.
    Systems that certify to their State that all compliance samples 
taken in the two years prior to the start of the IDSE were <= 0.040 mg/
L TTHM and <= 0.030 mg/L HAA5 are not required to collect additional 
DBP monitoring data because the Advisory Committee determined that 
these systems most likely would not have high peak DBP levels. EPA 
determined that this provision needed to be more specific for three 
groups of systems: (1) Those performing Stage 1 DBPR reduced 
monitoring, (2) large ground water systems, and (3) small systems 
required to conduct an early IDSE. Today's proposal clarifies that 
these systems may use a 40/30 certification. EPA recognizes that these 
systems may have less compliance data on which to base their 40/30 
certifications. However, EPA believes that the data that will be 
available are sufficient to make a determination on the most 
appropriate Stage 2B monitoring locations.
    c. Implementation. Systems are required to submit an IDSE report so 
that primacy agencies may review the system's IDSE data collection 
efforts and the Stage 2B monitoring locations recommended by the 
system. Systems serving at least 10,000 must submit their IDSE report 
two years after rule promulgation (which may be prior to primacy for 
some States). The M-DBP Advisory Committee recommended an 
implementation schedule that would allow systems sufficient time to 
make site-specific risk determinations and decisions regarding the 
simultaneous implementation of the Stage 2 DBPR and LT2ESWTR but not 
stretch out the compliance time frame too far into the future. This 
provision requires that medium and large systems conduct and complete 
site-specific risk determinations (i.e., the IDSE and LT2ESWTR 
Cryptosporidium monitoring) as soon as possible after rule 
promulgation. Since small systems cannot begin their microbial 
monitoring until after the results from the large system microbial 
monitoring have been analyzed, small systems have a longer compliance 
time frame.
    Systems that submit a 40/30 certification are required to submit 
that certification as part of the IDSE report and to include a 
recommended Stage 2B monitoring plan. The monitoring plan is required 
for these systems because the Stage 2B MCL compliance monitoring sites 
proposed today have fundamentally different objectives than the Stage 1 
DBPR monitoring sites. Additionally, many systems are required to have 
more Stage 2 compliance monitoring sites than Stage 1 sites because 
high HAA5 site may be different than high TTHM sites.
3. Request for Comment
    EPA requests comments on the IDSE requirement and whether it is a 
good tool to identify sites representative of high TTHM and high HAA5 
levels.
    a. Applicability. EPA requests comment on requiring large (serving 
10,000 or more people) nontransient noncommunity water systems to 
perform an IDSE. Should NTNCWSs serving fewer than 10,000 people be 
required to conduct an IDSE? EPA also requests comment upon whether 
States should be able to waive IDSE requirements for very small systems 
(serving fewer than 500 people). Are there objective criteria that the 
State should use in waiving the requirement? Should the State be 
allowed to grant very small system waivers based on some other 
criterion other than serving a population <500? For example, should the 
State be allowed to choose a higher population cutoff? Should the State 
be allowed to use a non-population criterion such as simplicity of 
distribution system to grant a very small system waiver? If so, what 
should this criterion be and how should qualification be demonstrated?
    b. Data collection. EPA requests comment on the requirements for 
each of the alternatives for data collection under the proposed IDSE 
including: the standard monitoring program, the system-specific study, 
and the 40/30 certification. EPA requests comment on whether systems 
with less than two years of routine monitoring data should be 
considered to have sufficient data to utilize the 40/30 certification.

[[Page 49595]]

Specifically EPA requests comment on whether systems on reduced 
monitoring, large ground water systems, and small systems required to 
conduct an IDSE within the first two years after promulgation should be 
prohibited from submitting a 40/30 certification.
    c. Implementation. EPA requests comment on the requirement that 
large and medium systems must collect data and prepare their IDSE 
report prior to State primacy. EPA requests comment from the States 
regarding whether they intend to be involved in the consultations with 
systems collecting data for IDSE or in the review of IDSE reports that 
are submitted prior to State primacy. EPA is developing a plan to 
implement the IDSE during the period prior to State primacy. EPA 
requests comment on any issues that should be addressed during this 
period to facilitate the IDSE.

I. Monitoring Requirements and Compliance Determination for Stage 2A 
and Stage 2B TTHM and HAA5 MCLs

1. What Is EPA Proposing Today?
    Today's proposal includes new requirements for how systems must 
monitor TTHM and HAA5 levels in their distribution systems and how 
systems must assess their monitoring results to determine compliance 
with TTHM and HAA5 MCLs. The new monitoring requirements are associated 
with the IDSE (described in section V.H) and Stage 2B of the proposed 
rule. The new compliance determination requirements relate to use of 
the locational running annual average (LRAA) for meeting proposed Stage 
2A and Stage 2B MCLs for TTHM and HAA5 (described in section V.D). This 
section presents these proposed monitoring and compliance determination 
requirements for Stage 2A, the IDSE, and Stage 2B.
    An important aspect of the proposed TTHM and HAA5 monitoring 
requirements is the use of two different approaches for determining the 
number of samples a system is required to collect. One approach is 
plant-based. Under the plant-based approach, a system's TTHM and HAA5 
sampling requirements are determined by the number of treatment plants 
in the system and, in the case of consecutive systems, the number of 
consecutive system entry points. The second approach is population-
based. Under the population-based approach, a system's sampling 
requirements are influenced by the number of people served, but not by 
the number of treatment plants. EPA is proposing population-based 
sampling requirements only for IDSE and Stage 2B monitoring by 
consecutive systems that purchase all of their finished water year-
round. However, EPA is requesting comment on applying a population-
based approach to all systems for the IDSE and Stage 2B compliance. The 
discussion of monitoring requirements in this section provides details 
on these two approaches.
    A number of factors affect DBP formation, including the type and 
amount of disinfectant used, water temperature, pH, amount and type of 
precursor material in the water, and the length of time that water 
remains in the treatment and distribution systems. For this reason, and 
because DBP levels can be highly variable throughout the distribution 
system (as discussed in section IV), today's proposal requires systems 
to collect IDSE and Stage 2B samples at specific locations in the 
distribution system and in accordance with a sampling schedule. For 
purposes of determining the number of required samples, EPA intends to 
maintain the provision in the Stage 1 DBPR (Sec.  141.132(a)(2)) that 
multiple wells drawing raw water from a single aquifer may, with State 
approval, be considered one plant, and prior approvals will remain in 
force unless withdrawn.
    a. Stage 2A. For Stage 2A of the proposed rule, compliance will be 
based on the compliance sampling sites and frequency established under 
the existing Stage 1 DBPR. Systems must continue to monitor for TTHM 
and HAA5 using a plant-based approach, as required under 40 CFR 
141.132. Using these monitoring results, systems must continue to 
demonstrate compliance with Stage 1 MCLs of 0.080 mg/L for TTHM and 
0.060 mg/L for HAA5, based on a running annual average (see 40 CFR 
141.133). In addition, systems must comply with the Stage 2A MCLs of 
0.120 mg/L for TTHM and 0.100 mg/L for HAA5, based on the LRAA at each 
Stage 1 DBPR monitoring location. Stage 1 DBPR provisions for systems 
to reduce the frequency of TTHM and HAA5 monitoring will still apply.
    Stage 2A will primarily affect surface water systems serving at 
least 10,000 people or systems with multiple plants, because these 
systems are required to monitor at more than one location in the 
distribution system. Most other systems take compliance samples at only 
one location under Stage 1 and in these cases, the calculated LRAA will 
be equal to the calculated RAA.
    b. IDSE. IDSE monitoring requirements are designed to identify 
locations within the distribution system with high TTHM and HAA5 
levels, which will serve as Stage 2B monitoring sites. The following 
discussion provides details on the IDSE standard monitoring program. 
Section V.H identifies other approaches by which systems can meet IDSE 
requirements of the rule.
    For IDSE monitoring, subpart H systems serving at least 10,000 
people must collect samples approximately every 60 days at eight 
distribution system sites per plant (these are in addition to Stage 1 
DBPR compliance monitoring sites). The distribution system residual 
disinfectant type determines the location of the eight sites, as shown 
in Table V-3.
    Subpart H systems serving fewer than 10,000 people and all ground 
water systems must collect IDSE samples at two distribution system 
sites per plant (at sites that are in addition to the Stage 1 DBPR 
compliance monitoring sites) as shown in Table V-3. Subpart H systems 
serving 500-9,999 people and ground water systems serving at least 
10,000 people must sample quarterly (approximately every 90 days); 
subpart H systems serving fewer than 500 people and ground water 
systems serving fewer than 10,000 people must sample semi-annually 
(approximately every 180 days).
    EPA is also proposing IDSE monitoring requirements for consecutive 
systems. For consecutive systems that both purchase finished water and 
treat source water to produce finished water, IDSE requirements are the 
same as for non-consecutive systems with the same population and source 
water type (see Table V-3). For these consecutive systems, each 
consecutive system entry point (defined in section V.C) is counted as 
one treatment plant for purposes of determining sampling requirements. 
However, the State may allow a system to consider multiple consecutive 
system entry points to be considered a single point.
    As noted previously, for consecutive systems that purchase all of 
their finished water year-round, EPA is proposing a population-based 
monitoring approach (see Table V-4) instead of a plant-based approach. 
Under the population-based approach, monitoring requirements are not 
influenced by the number of consecutive system entry points, but are 
based solely on the population served and the type of source water 
used. EPA believes the population-based approach is equitable and will 
provide representative DBP concentrations throughout distribution 
systems.

[[Page 49596]]



                                Table V-3.--Proposed IDSE Monitoring Requirements
----------------------------------------------------------------------------------------------------------------
                                                             Distribution system sample locations per plant per
                                Distribution                               monitoring period \1\
 System type and population        system       Number of ------------------------------------------------------
           served               disinfectant   monitoring                Near     Average
                                    type         periods     Total      entry    residence  High TTHM  High HAA5
                                                                        point       time    locations  locations
----------------------------------------------------------------------------------------------------------------
Subpart H =10,000  Chloramines....        \2\6          8          2          2          2          2
                              Chlorine.......        \2\6          8          1          2          3          2
Subpart H 500-9,999 or        Any............       \3\ 4          2          0          0          1          1
 Ground Water =10,000.
Subpart Any H <500 or Ground  Any............       \2\ 4          2          0          0          1          1
 Water <10,000.
                                              -------------
Consecutive Systems.........  Any............  --Consecutive systems that purchase 100% of their finished water
                                               year-round--see Table V.4.
                                               --Consecutive systems that also treat source water to produce
                                               finished water--plant-based monitoring at same location and
                                               frequency as a non-consecutive system with the same population
                                               and source water.
----------------------------------------------------------------------------------------------------------------
\1\ Samples must be taken at locations other than the existing Stage 1 DBPR monitoring locations. Dual sample
  sets (i.e., a TTHM and an HAA5 sample) must be taken at each site. Sampling locations should be distributed
  throughout the distribution system.
\2\ Approximately every 60 days.
\3\ Approximately every 90 days.
\4\ Approximately every 180 days.


   Table V-4. Population-Based Monitoring Frequencies and Locations Under IDSE for Consecutive Systems That Purchase 100% of Finished Water Year-Round
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                          Distribution system sample locations \1\
                                                                                                  ------------------------------------------------------
                                                                         Monitoring periods and                  Near
            Source water type               Population size category            frequency                       entry     Average   High TTHM  High HAA5
                                                                                                     Total      points   residence  locations  locations
                                                                                                                 \2\        time
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H...............................  0-499......................  Two 2 every 180 days).....          2  .........  .........          1          1
                                          500-4,999..................  Four (every 90 days)......          2  .........  .........          1          1
                                          5,000-9,999................                                      4  .........          1          2          1
                                          10,000-24,999..............  Six (every 60 days).......          8          1          2          3          2
                                          25,000-49,999..............                                     12          2          3          4          3
                                          50,000-99,999..............                                     16          3          4          5          4
                                          100,000-499,999............                                     24          4          6          8          6
                                          500,000-1,499,000..........                                     32          6          8         10          8
                                          1,500,000-4,999,999........                                     40          8         10         12         10
                                          =5,000,000......                                     48         10         12         14         12
Ground Water............................  0-499......................  Two (every 180 days)......          2  .........  .........          1          1
                                          500-9,999..................                                      2  .........  .........          1          1
                                          10,000-99,999..............  Four (every 90 days)......          6          1          1          2          2
                                          100,000-499,999............                                      8          1          1          3          3
                                          =500,000........                                     12          2          2          4         4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Samples must be taken at locations other than the existing Stage 1 DBPR monitoring locations. Dual sample sets (i.e., a TTHM and an HAA5 sample)
  must be taken at each site. Sampling locations should be distributed throughout the distribution system.
\2\ If the number of entry points to the distribution system is less than the specified number of sampling locations, additional samples must be taken
  equally at high TTHM and HAA5 locations. If there is an odd extra location number, a sample at a high TTHM location must be taken. If the number of
  entry points to the distribution system is more than the specified number of sampling locations, samples must be taken at entry points to the
  distribution system having the highest water flows.

    As a part of the monitoring schedule, all systems conducting IDSE 
monitoring must collect samples during the peak historical month for 
TTHM levels or water temperature. EPA will provide guidance to assist 
systems in choosing IDSE monitoring locations, including criteria for 
selecting high TTHM and HAA5 monitoring locations.
    c. Stage 2B. For those systems required to conduct an IDSE, Stage 
2B monitoring sites are based on the system's IDSE results and Stage 1 
DBPR compliance monitoring results. For those systems not required to 
conduct an IDSE, Stage 2B monitoring locations are based on the 
system's Stage 1 DBPR compliance monitoring results and an evaluation 
of the distribution system characteristics to identify additional 
monitoring locations, if required.
    Consistent with the Advisory Committee recommendations, the 
monitoring frequency for Stage 2B is structured so that systems that 
monitor quarterly under the Stage 1 DBPR will continue to monitor 
quarterly. In addition, the monitoring schedule must include the month 
with the highest historical DBP concentrations.
    Many systems on reduced monitoring under the Stage 1 DBPR will 
conduct Stage 2B compliance monitoring at different or additional 
locations than those used for Stage 1 compliance monitoring. Such 
systems must conduct routine monitoring for at least one year before 
being eligible for reduced monitoring under Stage 2B. Those systems 
that monitor at the same locations under both the Stage 1 DBPR and 
Stage 2B DBPR and have qualified for reduced monitoring under Stage 1 
may remain on reduced monitoring at the beginning of Stage 2B.

[[Page 49597]]

    EPA is proposing to require all systems to develop and maintain a 
DBP monitoring plan that must include the following information: 
monitoring locations, monitoring dates, compliance calculation 
procedures, and copies of any permits, contracts, or other agreements 
with third parties to sample, analyze, report, or perform any other 
monitoring requirement. Each system in a combined distribution system 
(as discussed in section V.C) must develop and maintain its own 
monitoring plan.
    To comply with the requirement for a monitoring plan, systems may 
develop a new plan or update the monitoring plan required under the 
Stage 1 DBPR (see Sec.  141.132(f)). In either case, the system must 
follow the monitoring plan, which will be based on the IDSE report 
submitted to the State, modified by any changes required by the State.
    Table V-5 summarizes proposed routine and reduced monitoring 
requirements for Stage 2B of today's rule for non-consecutive systems 
and for consecutive systems that also treat source water. Tables V-6 
and V-7 summarize proposed routine and reduced Stage 2B monitoring 
requirements for consecutive systems that purchase all of their 
finished water year-round. The proposed reduced monitoring requirements 
are consistent with the approach taken in the Stage 1 DBPR.

  Table V-5.--Proposed Stage 2B Routine and Reduced Monitoring Requirements for Non-Consecutive Systems and for
                 Consecutive Systems That Also Treat Source Water To Produce Finished Water \1\
----------------------------------------------------------------------------------------------------------------
                                                        Requirements to                           Trigger for
  System size and source water    Routine monitoring      qualify for     Reduced monitoring     returning to
              type                  (per plant) \2\   reduced monitoring      (per plant)     routine monitoring
----------------------------------------------------------------------------------------------------------------
Subpart H systems serving 4.0
 thn-eq>=10,000 people.            sets per quarter.   completed routine   sets per quarter.   mg/L as an RAA,
                                                       monitoring and                          or TTHM LRAA 0.040 mg/L
                                                       LRAAs are no more                       or HAA5 LRAA 0.030 mg/
                                                       and 0.030 mg/L,                         L.
                                                       respectively, and
                                                       TOC running
                                                       annual average
                                                       <=4.0 mg/L.
Subpart H systems serving 500 to  Two dual sample     One year of         Two dual sample     TOC 4.0
 9,999 people.                     sets per quarter    completed routine   sets per year \4\.  mg/L as an RAA,
                                   \3\.                monitoring and                          or Single Sample
                                                       all TTHM and HAA5                       of TTHM 0.060 mg/L or
                                                       than 0.040 mg/L                         HAA5 0.045 mg/L.\5\
                                                       respectively, and
                                                       TOC running
                                                       annual average
                                                       <=4.0 mg/L.
Subpart H systems serving <500    One dual sample     Monitoring may not  NA................  NA.
 people.                           set per year \5\    be reduced.
                                   \6\.
Ground water systems serving =10,000 people \7\.        sets per quarter    completed routine   sets per year \4\.  TTHM 0.060 mg/L or
                                                       all TTHM and HAA5                       HAA5 0.045 mg/L.\5\
                                                       than 0.040 mg/L
                                                       and 0.030 mg/L,
                                                       respectively.
Ground water systems serving 500  Two dual sample     One year of         Two dual samples    Single sample of
 to 9,999 people \7\.              sets per year \3\   completed routine   every third year    TTHM 0.040 mg/L or
                                                       all TTHM and HAA5                       HAA5 0.030 mg/L.\5\
                                                       than 0.040 mg/L
                                                       and 0.030 mg/L,
                                                       respectively.
Ground water systems serving      One dual sample     One year of         Two dual samples    Single sample of
 <500 people \7\.                  set per year \5\    completed routine   every third year    TTHM 0.040 mg/L or
                                                       all TTHM and HAA5                       HAA5 0.030 mg/L \5\
                                                       than 0.040 mg/L
                                                       and 0.030 mg/L,
                                                       respectively.
                                 ---------------------
Consecutive systems that also     System must meet the routine and reduced monitoring requirements of a non-
 treat source water.               consecutive system with the same population and source water. Monitoring may
                                   be reduced to the level required of that non-consecutive system.
----------------------------------------------------------------------------------------------------------------
\1\ Samples must be taken during representative operating conditions. Quarterly samples must be taken
  approximately every 90 days.
\2\ Systems will use the results of their IDSEs and Stage 1 DBPR compliance monitoring to recommend Stage 2B
  monitoring locations representative of high TTHM and HAA5 concentrations to the State in their IDSE reports.
  Systems must monitor at the recommended locations unless the State requires other locations.
\3\ If site and quarter of highest individual TTHM and HAA5 measurement are the same, monitoring is only
  required at one location if State approves.
\4\ If site and quarter of highest individual TTHM and HAA5 measurement are the same, monitoring is only
  required at one location.
\5\ If any single sample of TTHM 0.080 mg/L or HAA5 0.060 mg/L, system must go to
  increased monitoring of quarterly dual samples at each routine monitoring location and can return to routine
  monitoring when TTHM <=0.060 mg/L and HAA5 <=0.045 mg/L as LRAAs.
\6\ If the site or month of highest TTHM is not the same as the site or month of highest HAA5, the system must
  monitor for TTHM at the location of the highest TTHM LRAA during the month of highest TTHM single measurement
  and for HAA5 at the location of the highest HAA5 LRAA during the month of highest HAA5 single measurement.
\7\ Ground water systems are those not under the direct influence of surface water. For the purpose of
  determining the required number of samples, multiple wells drawing water from a single aquifer may, with State
  approval, be considered one treatment plant.

    i. Subpart H systems serving 10,000 or more people.
    Routine monitoring: Systems must take four dual sample sets (i.e., 
a TTHM and an HAA5 sample must be taken at each sampling site) per 
treatment plant per quarter. Systems must monitor at locations 
recommended in the IDSE report, unless the State has required other 
locations. Most systems must take samples at each plant in the system 
as follows: One dual sample set at the existing Stage 1 DBPR average 
residence time monitoring location with the highest TTHM or HAA5 LRAA, 
one dual sample set at a point representative of the highest HAA5 
levels, and two dual sample sets at points representative of the 
highest TTHM levels.
    Systems must schedule monitoring so that one quarter's monitoring 
is conducted during the peak historical month for high TTHM 
concentration and the other quarterly monitoring is

[[Page 49598]]

conducted approximately every 90 days on a predetermined schedule 
included in the system's monitoring plan.
    Reduced monitoring: Only systems with source water TOC <=4.0 mg/L 
as an RAA that have completed at least one year of routine monitoring 
may qualify for reduced monitoring (see Table V-5). Systems that have a 
TTHM LRAA <=0.040 mg/L and an HAA5 LRAA <=0.030 mg/L at all sites, in 
addition to a source water TOC RAA <= 4.0 mg/L, may reduce the 
monitoring frequency for TTHM and HAA5 to two dual sample sets (one 
each at sites representative of the highest HAA5 and TTHM LRAAs) per 
treatment plant per quarter. Systems on a reduced monitoring schedule 
may remain on that reduced schedule as long as the LRAA of all samples 
taken in the year is no more than 0.040 mg/L for TTHM and 0.030 mg/L 
for HAA5 or if source water TOC exceeds 4.0 mg/L as an RAA. Systems 
must revert to routine monitoring in the quarter immediately following 
any quarter in which the LRAA for any monitoring location exceeds 0.040 
mg/L for TTHM or 0.030 mg/L for HAA5. Additionally, the State may 
return a system to routine monitoring at the State's discretion.
    Compliance determination: A PWS is in compliance with Stage 2B when 
the TTHM and HAA5 LRAAs for each sample location, computed quarterly, 
are less than or equal to the Stage 2B MCLs of 0.080 mg/L and 0.060 mg/
L, respectively. Otherwise, the system is out of compliance.
    ii. Subpart H systems serving 500 to 9,999 people. Routine 
monitoring: Systems must monitor quarterly for each treatment plant by 
taking two dual sample sets, one each at sites representative of high 
HAA5 levels and high TTHM levels (as recommended in the IDSE report). 
However, if the State determines that the sites representative of the 
high TTHM and HAA5 levels are at the same location, the State may 
determine that the system is only required to monitor at one site per 
treatment plant.
    Systems must conduct quarterly monitoring during the peak 
historical month for TTHM with quarterly samples taken approximately 
every 90 days on a predetermined schedule specified in the system's 
monitoring plan. All samples must be taken as dual sample sets (i.e., a 
TTHM and an HAA5 sample must be taken at each site).
    Reduced monitoring: To qualify for reduced monitoring, systems must 
meet certain prerequisites (see Table V-5). Systems eligible for 
reduced monitoring may reduce the monitoring frequency from quarterly 
to annually. Samples must be taken during the month(s) of peak 
historical TTHM and HAA5 levels at the same locations specified under 
routine monitoring. Systems that have their highest TTHM and HAA5 
levels in the same month must take dual sample sets at both the high 
TTHM and high HAA5 sites. If the high months for TTHM and HAA5 are not 
the same, the system must take dual sample sets in both the high TTHM 
and high HAA5 months. Systems on a reduced monitoring schedule may 
remain on that reduced schedule as long as the annual sample taken at 
each location is no more than 0.060 mg/L for TTHM and 0.045 mg/L for 
HAA5 or if source water TOC exceeds 4.0 mg/L as an RAA. Systems that do 
not meet these levels must revert to routine monitoring in the quarter 
immediately following the quarter in which the system exceeded 0.060 
mg/L for TTHM or 0.045 mg/L for HAA5. Additionally, the State may 
return a system to routine monitoring at the State's discretion.
    Compliance determination: A PWS is in compliance with Stage 2B when 
the LRAAs of each sample location, computed quarterly, are less than or 
equal to the MCLs. Otherwise, the system is out of compliance. If the 
annual sample taken under reduced monitoring exceeds the MCL, the 
system must resume quarterly monitoring but is not immediately in 
violation of the MCL. The system is out of compliance if the LRAA of 
the quarterly sample for the past four quarter exceeds the MCL.
    iii. Subpart H systems serving fewer than 500 people. Routine 
monitoring: Systems are required to sample annually for each treatment 
plant at the location with high TTHM and HAA5 values during the month 
of peak historical TTHM levels. The system must take one dual sample 
set at the site representative of the high HAA5 and TTHM levels (at the 
Stage 1 DBPR monitoring site or as recommended in the IDSE report), 
unless the State determines that the highest TTHM site and the highest 
HAA5 site are not at the same location or are not during the same 
quarter. If the State determines that the highest TTHM and highest HAA5 
do not occur in the same location, the system is required to take two 
samples, an HAA5 sample at the site representative of the high HAA5 
levels and a TTHM sample at the site representative the high TTHM 
levels. If the State determines that the highest TTHM and highest HAA5 
do not occur in the same quarter, the systems is required to take one 
sample in the high TTHM quarter and one sample in the high HAA5 
quarter. If the annual sample exceeds the MCL for either TTHM or HAA5, 
the system must monitor quarterly at the previously determined 
monitoring locations.
    Reduced monitoring: These systems may not reduce monitoring to less 
frequently than annually. Systems on increased (quarterly) monitoring 
may return to routine monitoring if the LRAAs of quarterly samples are 
no more than 0.060 mg/L for TTHM and 0.045 mg/L for HAA5.
    Compliance determination: A PWS is in compliance when the annual 
sample (or LRAA of quarterly samples, if increased or additional 
monitoring is conducted) is less than or equal to the MCL. If the 
annual sample exceeds the MCL, the system must conduct increased 
(quarterly) monitoring but is not immediately in violation of the MCL. 
The system is out of compliance if the LRAA of the quarterly samples 
for the past four quarters exceeds the MCL.
    iv. Ground water systems serving 10,000 or more people. Routine 
monitoring: Systems are required to monitor quarterly for each 
treatment plant in the system by taking two dual sample sets, one each 
at sites representative of high HAA5 levels and high TTHM levels (as 
recommended in the IDSE report). However, if the State determines that 
the sites representative of the high TTHM and HAA5 levels are the same, 
the State may determine that the system only has to monitor at one site 
per treatment plant. One quarterly sample must be taken during the peak 
historical month for TTHM, with subsequent quarterly samples taken 
approximately every 90 days.
    Reduced monitoring: To qualify for reduced monitoring, systems must 
meet certain requirements (see Table V-5). Systems eligible for reduced 
monitoring may reduce the monitoring frequency from quarterly to 
annually. Samples must be taken during the month(s) of peak historical 
TTHM and HAA5 levels at the same locations specified under routine 
monitoring. Systems that have their highest TTHM and HAA5 levels in the 
same quarter must take dual sample sets at both the high TTHM and high 
HAA5 sites. If the quarter for high TTHM and high HAA5 are not the 
same, the system must take dual sample sets in both the high TTHM and 
high HAA5 quarters. Systems on a reduced monitoring schedule may remain 
on that reduced schedule as long as the annual sample taken at each 
location is no more than 0.060 mg/L for TTHM and 0.045 mg/L for HAA5. 
Systems that do not meet these levels must revert to routine monitoring 
in the quarter immediately following the quarter in which the system 
exceeded 0.060 mg/L for TTHM or 0.045 mg/L for HAA5. Additionally, the 
State may return a

[[Page 49599]]

system to routine monitoring at the State's discretion.
    Compliance determination: A PWS is in compliance with Stage 2B when 
the locational running annual average of each sample location, computed 
quarterly, is less than or equal to the MCL. Otherwise, the system is 
out of compliance. If the annual sample exceeds the MCL, the system 
must conduct increased (quarterly) monitoring but is not immediately in 
violation of the MCL. The system is out of compliance if the LRAA of 
the quarterly sample for the past four quarter exceeds the MCL.
    v. Ground water systems serving fewer than 10,000 people. Routine 
monitoring: Systems serving 500 to 9,999 people are required to take 
two dual sample sets annually, one each at sites representative of high 
HAA5 levels and high TTHM levels (as recommended in the IDSE report). 
However, if the State determines that the sites representative of the 
high TTHM and HAA5 levels are the same, the State may allow the system 
to monitor at only one site per treatment plant. If the State makes a 
determination that high TTHM and high HAA5 occur in different quarters, 
the system must monitor accordingly. If the annual sample exceeds the 
MCL for either TTHM or HAA5, the system must monitor quarterly at the 
previously determined monitoring locations.
    Systems serving fewer than 500 people are required to take one dual 
sample set at the site representative of both high HAA5 and TTHM 
levels, unless the State determines that the high TTHM site and the 
high HAA5 site are not at the same location. If the State makes this 
determination, the system is required to take samples at two locations, 
an HAA5 sample at the site representative of the high HAA5 levels and a 
TTHM sample at the site representative of the high TTHM levels. If the 
State makes a determination that high TTHM and high HAA5 occur in 
different quarters, the system must monitor accordingly. If the annual 
sample exceeds the MCL for either TTHM or HAA5, the system must monitor 
quarterly at the previously determined monitoring locations.
    Reduced monitoring: To qualify for reduced monitoring, systems must 
meet certain prerequisites (see Table V-5). Systems eligible for 
reduced monitoring may reduce the monitoring frequency for TTHM and 
HAA5 to every third year. Systems are required to take two water 
samples, at sites representative of high HAA5 and TTHM levels (as 
discussed under routine monitoring) during the month of peak TTHM 
levels. Systems on a reduced monitoring schedule may remain on that 
reduced schedule as long as the sample taken every third year is no 
more than 0.040 mg/L for TTHM and 0.030 mg/L for HAA5. Systems that do 
not meet these levels must resume routine annual monitoring until their 
annual average is no more than 0.040 mg/L for TTHM and 0.030 mg/L for 
HAA5.
    Compliance determination: A PWS is in compliance when the annual 
sample (or LRAA of quarterly samples, if increased or additional 
monitoring is conducted) is less than or equal to the MCL. If the 
annual sample exceeds the MCL, the system must conduct increased 
(quarterly) monitoring but is not immediately in violation of the MCL. 
The system is out of compliance if the LRAA of the quarterly samples 
for the past four quarters exceeds the MCL.
    vi. Consecutive systems. Routine monitoring: Monitoring 
requirements are determined by whether the consecutive system purchases 
all of its finished water year-round or also treats source water, along 
with the population served and source water type of the wholesale 
system (unless the consecutive system also has a surface water or 
ground water under the direct influence of surface water (GWUDI) source 
and the wholesale system is only ground water, in which case the 
consecutive system is classified as a subpart H system). Section V.C. 
of today's document provides a more detailed discussion of consecutive 
system issues.
    As noted earlier, for consecutive systems that purchase all their 
finished water year-round, EPA is proposing population-based 
monitoring. The proposed number of monitoring locations is based on the 
source water type of the wholesale system and consecutive system 
population. Proposed Stage 2B compliance monitoring requirements for 
consecutive systems that purchase all their finished water are 
contained in Table V-6. Consecutive systems that also treat source 
water to produce finished water must monitor at the same locations and 
same frequency as a non-consecutive system with the wholesale system's 
source water type and the consecutive system's population.

   Table V-6.--Proposed Population-Based Routine Monitoring Routine Frequencies and Locations Under Stage 2B for Consecutive Systems That Purchase All
                                                             Their Finished Water Year-Round
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                              Distribution system sample location \2\
                                                                                                         -----------------------------------------------
                                                                                                                                               Existing
         Source water type                  Population size category          Monitoring frequency \1\               Highest      Highest      stage 1
                                                                                                           Total       TTHM         HAA5      compliance
                                                                                                                    locations    locations    locations
                                                                                                                                                 \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H..........................  0-499................................  per year....................    2 \4\            1            1  ...........
                                     500-4,999............................  per quarter.................    2 \4\            1            1  ...........
                                     5,000-9,999..........................  per quarter.................        2            1            1  ...........
                                     10,000-24,999........................  per quarter.................        4            2            1            1
                                     25,000-49,999........................  per quarter.................        6            3            2            1
                                     50,000-99,999........................  per quarter.................        8            4            2            2
                                     100,000-499,999......................  per quarter.................       12            6            3            3
                                     500,000-1,499,000....................  per quarter.................       16            8            4            4
                                     1,500,000-4,999,999..................  per quarter.................       20           10            5            5
                                     =5,000,000................  per quarter.................       24           12            6            6
                                     0-499................................  per year....................    2 \4\            1            1  ...........
                                     500-9,999............................  per year....................        2            1            1  ...........
Ground Water.......................  10,000-99,999........................  per quarter.................        4            2            1            1
                                     100,000-499,999......................  per quarter.................        6            3            2            1
                                     =500,000..................  per quarter.................        8            4            2           2
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ All systems must take at least one dual sample set during month of highest DBP concentrations. Systems on quarterly monitoring must take dual sample
  sets approximately every 90 days.

[[Page 49600]]

 
\2\ Locations based on system recommendations for Stage 2B monitoring locations in IDSE report to the State, unless State requires different or
  additional locations. Locations should be distributed through distribution system to the extent possible.
\3\ Alternate between highest HAA5 LRAA and highest TTHM LRAA locations among the existing Stage 1 compliance locations. If the number of existing Stage
  1 compliance locations is fewer than the specified number for Stage 2B, alternate between highest HAA5 LRAA locations and highest TTHM LRAA locations
  from the IDSE.
\4\ System is required to take individual TTHM and HAA5 samples at the locations with the highest TTHM and HAA5 concentrations, respectively. Only one
  location with a dual sample set per monitoring period is needed if highest TTHM and HAA5 concentrations occur at the same location.

    Reduced monitoring: Consecutive systems can qualify for reduced 
monitoring if the LRAA at each location is <=0.040 mg/L for TTHM and 
<=0.030 mg/L for HAA5 based on at least one year of monitoring at Stage 
2B locations. Consecutive systems that purchase all of their finished 
water year-round may reduce their monitoring as specified in Table V-7. 
Consecutive systems that also treat source water to produce finished 
must conduct reduced monitoring at the same locations and same 
frequency as a non-consecutive system with the wholesale system's 
source water type and the consecutive system's population.

  Table V-7.--Reduced Monitoring Frequency for Consecutive Systems That
                           Buy All Their Water
------------------------------------------------------------------------
      Population served        Reduced monitoring frequency and location
------------------------------------------------------------------------
                            Subpart H systems
------------------------------------------------------------------------
<500.........................  Monitoring may not be reduced.
500 to 4,999.................  1 TTHM and 1 HAA5 sample per year at
                                different locations or during different
                                quarters if the highest TTHM and HAA5
                                occurred at different locations or
                                different quarters or 1 dual sample per
                                year if the highest TTHM and HAA5
                                occurred at the same location and
                                quarter.
5,000 to 9,999...............  2 dual sample sets per year; one at the
                                location with the highest TTHM single
                                measurement during the quarter that the
                                highest single TTHM measurement
                                occurred, one at the location with the
                                highest HAA5 single measurement during
                                the quarter that the highest single HAA5
                                measurement occurred.
10,000 to 24,999.............  2 dual sample sets per quarter at the
                                locations with the highest TTHM and
                                highest HAA5 LRAAs.
25,000 to 49,999.............  2 dual sample sets per quarter at the
                                locations with the highest TTHM and
                                highest HAA5 LRAAs.
50,000 to 99,000.............  4 dual sample sets per quarter at the
                                locations with the two highest TTHM and
                                two highest HAA5 LRAAs.
100,000 to 499,999...........  4 dual sample sets per quarter at the
                                locations with the two highest TTHM and
                                two highest HAA5 LRAAs.
500,000 to 1,499,999.........  6 dual sample sets per quarter at the
                                locations with the three highest TTHM
                                and three highest HAA5 LRAAs.
1,500,000 to 4,999,999.......  6 dual sample sets per quarter at the
                                locations with the three highest TTHM
                                and three highest HAA5 LRAAs.
=5,000,000........  8 dual sample sets per quarter at the
                                locations with the four highest TTHM and
                                four highest HAA5 LRAAs.
------------------------------
                          Ground water systems
------------------------------------------------------------------------
<500.........................  1 TTHM and 1 HAA5 sample every third year
                                at different locations or during
                                different quarters if the highest TTHM
                                and HAA5 occurred at different locations
                                or different quarters or 1 dual sample
                                every third year if the highest TTHM and
                                HAA5 occurred at the same location and
                                quarter.
500 to 9,999.................  1 TTHM and 1 HAA5 sample every year at
                                different locations or during different
                                quarters if the highest TTHM and HAA5
                                occurred at different locations or
                                different quarters or 1 dual sample
                                every year if the highest TTHM and HAA5
                                occurred at the same location and
                                quarter.
10,000 to 99,000.............  2 dual sample sets per year; one at the
                                location with the highest TTHM single
                                measurement during the quarter that the
                                highest single TTHM measurement occurred
                                and one at the location with the highest
                                HAA5 single measurement during the
                                quarter that the highest single HAA5
                                measurement occurred.
100,000 to 1,499,999.........  2 dual sample sets per quarter; at the
                                locations with the highest TTHM and
                                highest HAA5 LRAAs.
=1,500,000........  4 dual sample sets per quarter; at the
                                locations with the two highest TTHM and
                                two highest HAA5 LRAAs.
------------------------------------------------------------------------

    Systems may remain on reduced monitoring as long as the TTHM LRAA 
<=0.040 mg/L and the HAA5 LRAA <=0.030 mg/L at each monitoring location 
for systems with quarterly reduced monitoring. If the LRAA at any 
location exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 or 
if the source water annual average TOC level, before any treatment, 
exceeds 4.0 mg/L at any of the system's treatment plants treating 
surface water or ground water under the direct influence of surface 
water, the system must resume routine monitoring. For systems with 
annual or less frequent reduced monitoring, systems may remain on 
reduced monitoring as long as each TTHM sample <=0.060 mg/L and each 
HAA5 sample <=0.045 mg/L. If the annual sample at any location exceeds 
either 0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or if the source 
water annual average TOC level, before any treatment, exceeds 4.0 mg/L 
at any treatment plant treating surface water or ground water under the 
direct influence of surface water, the system must resume routine 
monitoring.
    Compliance determination: A PWS is in compliance when the annual 
sample or LRAA of quarterly samples is less than or equal to the MCLs. 
If an annual sample exceeds the MCL, the system must conduct increased 
(quarterly) monitoring but is not immediately in violation of the MCL. 
The system is out of compliance if the LRAA of the quarterly samples 
for the past four quarters exceeds the MCL.
2. How Was This Proposal Developed?
    The proposed monitoring requirements for the IDSE and Stage 2B 
primarily follow a plant-based approach that was adopted from the 1979 
TTHM Rule and the Stage 1 DBPR. This approach includes differences in 
monitoring frequency between surface water and ground water sources, 
and between large and small systems. However, the proposed monitoring 
requirements differ from Stage 1 DBPR requirements in certain areas, 
including (a) sampling intervals for quarterly monitoring, (b) reduced 
monitoring frequency, (c) different sampling locations by disinfectant 
type (for the IDSE), and (d) population-based monitoring requirements 
for certain consecutive systems. This subsection

[[Page 49601]]

presents the basis for these requirements.
    a. Sampling intervals for quarterly monitoring. Today's proposal 
requires systems conducting routine quarterly monitoring to sample 
approximately every 90 days. This provision modifies the approach used 
in the 1979 TTHM rule and the Stage 1 DBPR, which requires certain 
systems to conduct monitoring based on calendar quarters.
    When systems are required to monitor based on calendar quarters, 
systems can choose to cluster samples during times of the year when DBP 
levels are lower (DBPs tend to form more slowly in colder water 
temperatures). For example, a system could sample in December (at the 
end of the fourth quarter) and again in January (at the beginning of 
the first quarter) when the water is the coldest and sample in April 
(at the beginning of the second quarter) and September (at the end of 
the third quarter) at either end of the hot summer months.
    To address the concern with systems not sampling during months with 
the highest DBP levels, EPA is proposing to require systems to monitor 
during the month of highest historical DBP concentrations and require 
that systems monitor approximately every 90 days. EPA believes that 
this new monitoring strategy will improve public health protection 
because systems will be required to monitor when high DBP levels are 
expected, and the LRAA will better reflect actual exposure during the 
year.
    b. Reduced monitoring frequency. Today's proposal contains 
provisions allowing reduced routine monitoring when certain criteria 
are fulfilled (shown in Table V-5 and V-7). EPA believes that more 
stringent standards are necessary to ensure public health protection 
when systems reduce the frequency of their DBP monitoring. Under the 
reduced monitoring provisions, systems must collect samples during the 
months of highest DBP occurrence. For systems sampling annually under 
the reduced monitoring provisions, EPA believes that public health 
protection would likely be ensured throughout the year if the high 
values are known to be below 0.060 mg/L for TTHM and 0.045 mg/L for 
HAA5. Systems monitoring every three years must maintain single samples 
under 0.040 mg/L for TTHM and 0.030 mg/L for HAA5 to ensure adequate 
public health protection over the course of the three years.
    c. Different IDSE sampling locations by disinfectant type. Today's 
proposal contains different requirements for IDSE monitoring locations 
based on the disinfectant residual used in the distribution system. 
Systems that use chloramines are required to select more near-entry 
point monitoring sites for the IDSE than chlorinated systems of similar 
size and source water type. This is due to differences in DBP formation 
under chloraminated and chlorinated conditions. Chloramine residuals 
are more stable than chlorine residuals and do not react as readily 
with organic compounds in the water. Based on evaluation of Information 
Collection Rule data, DBP concentrations in chloraminated systems vary 
less throughout the distribution system than in chlorinated systems. 
HAA5, in particular, can peak at or near the entry point to the 
distribution system in a chloraminated system (USEPA 2003o).
    d. Population-based monitoring requirements for certain consecutive 
systems. While the Advisory Committee recommended basic principles for 
how consecutive systems should be regulated, it did not recommend how 
EPA should explicitly address some of the unique situations that 
pertain to consecutive systems. In this regard, consecutive systems 
that purchase all of their finished water year-round are different than 
other systems in that they do not have a treatment plant. Rather, these 
systems often receive water from multiple wholesale systems or through 
multiple consecutive system entry points on a seasonal or intermittent 
basis. Because a plant-based monitoring approach (which counts treated 
water distribution system entry points from different entities as 
plants) would be very difficult to implement for consecutive systems 
that purchase all of their finished water year-round, EPA is proposing 
a population-based approach for such systems.
    Under a population-based approach, the frequency of monitoring is 
based on the population served and remains the same regardless of how 
many entities are providing water to the consecutive system at 
different times of the year. The population categories and associated 
monitoring frequencies in Tables V-4 and V-6 for IDSE and Stage 2B 
routine monitoring reflect EPA's consideration that distribution system 
complexity generally increases as the population served grows. 
Increasing distribution system complexity warrants more monitoring to 
represent DBP occurrence.
    EPA developed the proposed population-based monitoring requirements 
in accordance with certain guidelines. These are stated as follows:

--The sampling frequency for surface water systems should be greater 
than for ground water systems. The basis for this is that, in general, 
systems using surface water or mixed source water supplies are likely 
to experience higher and more variable DBP occurrence over time than 
systems using ground water exclusively.
--Smaller systems should be allowed to monitor less frequently per 
location than larger systems because their distribution systems are 
generally less complex and monitoring costs on a per capita basis are 
much higher.
--For systems using surface water, the ratio of IDSE sample locations 
to the number of routine sample locations required for Stage 2B should 
be approximately 2:1 (consistent with Advisory Committee 
recommendations for plant-based monitoring). IDSE sampling is intended 
to identify distribution system locations with high DBP levels and 
should, therefore, be more thorough than routine monitoring.
--Because ground water systems have much less variable DBP levels 
within the distribution system than surface water systems (see section 
IV), a smaller number of additional IDSE monitoring locations is 
warranted.
--Distribution system sampling locations should be approximately 
consistent with the proposed plant-based approach as recommended by the 
Advisory Committee. This will capture the locations with the high TTHM 
and HAA5 LRAAs identified in the IDSE, but also include Stage 1 
compliance locations with high TTHM and HAA5 for historical tracking.

    Consistent with the first two guidelines, the proposed population-
based monitoring requirements maintain the same monitoring frequency 
per sample location as proposed under the plant-based approach. The 
following subsection provides further discussion of the population-
based approach as it might apply to all systems.
3. Request For Comment
    EPA is requesting comments on the proposed monitoring requirements. 
This subsection begins with a list of specific questions related to the 
proposed requirements for IDSE and Stage 2B monitoring. This is 
followed by a discussion of issues associated with plant-based 
monitoring requirements and a request for comment on potential 
approaches to address these issues, including the extension of 
population-based monitoring requirements to all systems under the Stage 
2 DBPR.
    a. Proposed IDSE and Stage 2B monitoring requirements. EPA is

[[Page 49602]]

requesting comment on a number of specific aspects of the proposed 
monitoring requirements.

--Should EPA require all systems that are on reduced monitoring to 
revert to routine monitoring during the IDSE monitoring period to allow 
for more data to be evaluated in the IDSE report to better select Stage 
2B monitoring locations? Or should EPA require a system to be on 
routine monitoring during the IDSE monitoring period in order to be 
eligible for an IDSE waiver? What limitations, if any, should EPA put 
on system eligibility for an IDSE waiver?
--Should EPA require different IDSE monitoring locations for subpart H 
systems based on the residual disinfectant (chlorine or chloramines) in 
light of the possible difficulties for implementation and data 
management? Should EPA specify monitoring locations in the rule 
language for samples intended to represent exposure for people in high-
rise buildings? Should monitoring location selection be addressed in 
guidance? Where should these locations be so that they are truly 
representative of the levels of DBPs in water actually being consumed 
in these kinds of structures?
--Is a population-based monitoring approach (instead of a plant-based 
monitoring approach) for consecutive systems that purchase all of their 
finished water year-round appropriate and, if so, is the population-
based approach proposed today adequate?

    EPA solicits comment on the significance of monitoring and 
implementation issues such as common aquifer determinations, 
consecutive system entry point determinations, seasonal plants, and 
monitoring inequities, and whether the proposed monitoring requirements 
should be modified. EPA also solicits comment on modifying the proposed 
monitoring requirements to address these issues, in part, with 
provisions such as the following:

--Should EPA set a limit on the maximum number of IDSE and routine 
monitoring samples that could be required? Should this limit be 
different for systems using ground water or surface water or mixed 
systems? For different system size categories? What rationale should be 
used to specify maximum sample numbers?
--Should a provision be included that would allow States to reduce the 
sampling frequency, beyond those currently proposed (i.e., common 
aquifer determinations and low DBP levels)? If so, should specific 
criteria for systems to qualify for State approval of reduced 
monitoring be specified in the rule?
--What, if any, criteria should be set by which systems with very large 
distribution systems but few plants would be required to conduct 
additional IDSE or routine monitoring, beyond that currently proposed?
--For subpart H mixed systems, should States be given discretion to 
reduce routine compliance monitoring samples intended to represent 
ground water sources, since such sources typically have lower precursor 
levels and produce lower DBP concentrations?
--Should EPA allow or require systems to reallocate plant-based IDSE 
monitoring locations from small plants to large plants? From plants 
with better water quality (based on expected lower DBP formation) to 
poorer water quality? What criteria should be used?

    b. Plant-based vs. population-based monitoring requirements. The 
proposed monitoring requirements incorporate a plant-based approach for 
all systems other than consecutive systems that purchase all of their 
finished water year-round. The plant-based approach was adopted from 
the 1979 TTHM Rule and the Stage 1 DBPR and derives from the assumption 
that as systems increase in size, they will tend to have more plants 
(with different sources and treatment) and increased complexity. This 
warrants increased monitoring to represent DBP occurrence in the 
distribution system.
    EPA has identified a number of issues related to the use of a 
plant-based monitoring approach under the Stage 2 DBPR. The following 
discussion presents these issues and solicits comment on approaches to 
address them, including the use of population-based monitoring 
requirements.
    i. Issues with plant-based monitoring requirements. One issue with 
a plant-based monitoring approach is that it can result in 
disproportionate monitoring requirements for systems serving the same 
number of people. This occurs because the required number of sampling 
sites increases with the number of plants that feed disinfected water 
into a distribution system. Consequently, some systems, depending upon 
their size, the number of treatment plants, and the nature of their 
distribution system, will be required to collect relatively large or 
small numbers of TTHM and HAA5 samples relative to their population 
served.
    Table V-8 reflects EPA estimates of the number of plants per system 
by system size category for systems using ground water and subpart H 
systems. Subpart H systems include systems that use ground water as a 
source because under the proposal, ground water plants in subpart H 
systems are treated as surface water plants for purposes of determining 
monitoring requirements. While the proposed plant-based requirements 
distinguish sampling requirements by three systems sizes (<500 people, 
500-9999 people, and 10,000 or more people), Table V-8 includes 
additional size categories to reflect the potential inequities in 
sampling requirements among different-sized systems.

                                  Table V-8.--Number of Treatment Plants per System (Based on Data From 1995 CWSS (1))
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                     No. of treatment plants per system
                                                                          No. of   ---------------------------------------------------------------------
          Source water type                  Population served          systems in      10th                           90th         95th
                                                                         database    percentile   Median    Mean    percentile   percentile    Maximum
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H...........................  0-499..........................          124            1        1      1.4            2            3            5
                                      500-4,999......................          146            1        1      1.3            2            3            6
                                      5,000-9,999....................           64            1        1      1.7            3            4            6
                                      10,000-24,999..................           59            1        1      2.0            3            4           18
                                      25,000-49,999..................           46            1        1      2.2            4            6            9
                                      50,000-99,999..................           76            1        2      3.4            6           12           34
                                      100,000-499,999................           51            1        2      3.0            5           10           21
                                      =500,000............           23            2        4      5.8           10           13           56
Ground Water........................  0-499..........................          181            1        1      1.4            3            4           11
                                      500-9,999......................          332            1        1      1.8            3            4           13

[[Page 49603]]

 
                                      10,000-99,999..................          128            1        4      4.2            9           11           18
                                      =100,000............           21            1        3      9.9           31           32          33
--------------------------------------------------------------------------------------------------------------------------------------------------------
(1) Results from analysis of 1995 CWSS data (Question Q18). The analysis uses a statistical bootstrapping approach to generate the number of plants per
  system. Details of this analysis are described in the 2002 revisions to the Model Systems Report [to be published]. The maximums reflect the maximum
  number of plants per system among the respondents to the 1995 CWSS. Since the 1995 CWSS database only reflects a fraction of all the systems in the
  respective size categories, some systems are likely to have a higher number of plants per system than the maximums listed in this table.

    Noteworthy in Table V-8 are the wide ranges of number of plants per 
system in the various size categories for both ground water and surface 
water systems and, consequently, the wide range of potential monitoring 
implications. Since the number of treatment plants directly influences 
the number of samples required, systems serving the same number of 
people may have more than a 10-fold difference in required sampling, 
depending on the numbers of plants in their systems. For example, Table 
V-8 indicates that for ground water systems serving at least 10,000 
people, at least 10% of the systems had only one treatment plant, while 
10% (90th percentile) had 10 or more treatment plants.
    While Table V-8 does not take into account factors that may reduce 
monitoring requirements, such as common aquifer determinations, EPA 
believes these data indicate that DBP sampling requirements based on 
the number of water treatment plants per system may be excessive for 
many systems. This is particularly the case for those systems with many 
ground water plants, since their DBP levels are often low and 
relatively stable.
    Conversely, for other systems, such as large surface water systems 
with one plant, plant-based monitoring requirements may not require 
enough samples to fairly represent DBP occurrence in the distribution 
system. For example, under the plant-based approach, a system with only 
one plant serving 100,000--499,000 people would have the same sampling 
requirements as a system with one plant serving 11,000 people. The 
larger of these two systems is likely to have much more pipe length and 
other complex factors influencing DBP formation (such as number of 
storage tanks or booster chlorination points in the distribution 
system). Also, systems with multiple plants must take the same number 
of samples per plant, even if one plant provides a much higher 
percentage of the water than another.
    Another issue with plant-based monitoring requirements is when 
plants or consecutive system entry points are operated seasonally or 
intermittently. A monitoring location that represents a plant or entry 
point during a monitoring period when it is in operation will not be 
representative when that plant or entry point it is not in operation.
    A third issue is requirements for consecutive systems. For 
consecutive systems that also treat source water to produce finished 
water, each consecutive system entry point is considered a treatment 
plant for the purpose of determining monitoring requirements, except 
when the State allows multiple entry points to be treated as a single 
plant (see section V.C. for further discussion). Each entry point is 
treated as a separate plant to recognize different source waters and 
treatment (resulting in different DBP levels) from the wholesale 
system(s) and the treatment plants(s) operated by the consecutive 
system. However, under this plant-based approach, State determinations 
of monitoring requirements for consecutive systems will be complicated, 
especially in large combined distribution systems with many connections 
between systems.
    ii. Approaches to addressing issues with plant-based monitoring. 
EPA is requesting comment on two approaches to address the issues with 
plant-based monitoring requirements described in this subsection. One 
approach is to keep the proposed plant-based monitoring approach and 
add new provisions to address specific concerns. Another approach is to 
base monitoring requirements on population served in lieu of the number 
of water treatment plants per system. The following paragraphs describe 
each approach.
    EPA could maintain a plant-based monitoring approach and try to 
address the related issues described in this subsection through 
modifying the proposed monitoring requirements with provisions like the 
following:

--Set a limit on the maximum number of IDSE and routine monitoring 
samples that could be required. EPA believes that this limit should be 
different for systems using ground water or surface water or mixed 
systems and for different system size categories. However, the Agency 
has not developed a rationale to specify maximum sample numbers for 
specific system categories.
--Include a provision that would allow States to reduce the required 
number of samples for reasons other than those currently proposed 
(i.e., common aquifer determinations and low DBP levels). EPA would 
have to develop specific criteria in the rule for systems to qualify 
for State approval of reduced monitoring. For example, in subpart H 
mixed systems, States could be given discretion to reduce routine 
compliance monitoring for ground water sources, since such sources 
typically have lower DBP concentrations.
--Develop criteria by which systems with very large distribution 
systems but with few plants would be required to conduct additional 
IDSE or routine monitoring in order to better characterize DBP exposure 
throughout the distribution system.

    These provisions would allow for some issues to be addressed, but 
would make implementation complex and could add a significant burden to 
States.
    An alternative approach to addressing the issues with plant-based 
monitoring requirements is to apply population-based monitoring 
requirements to all systems. Under a population-based monitoring 
approach, the total system population served and the source water type 
would determine the number of IDSE and routine monitoring samples 
taken. Monitoring requirements would not be based on the number of 
plants per system or consecutive system entry points. States would not 
be required to make common aquifer determinations or address whether 
plants are combined into a single pipe prior to entering the 
distribution system.
    Proposed population-based monitoring requirements for

[[Page 49604]]

consecutive systems that purchase all their finished water year-round 
are shown in Tables V-4, V-6, and V-7. Also, the proposed rule language 
in subparts U and V contains requirements for population-based 
monitoring similar to what might be required for all systems. EPA 
believes that through using a broader array of system size categories 
than under the plant-based approach, population-based monitoring could 
result in an equitable proportioning of DBP sampling requirements. 
Tables V-9 and V-10 compare the proposed numbers of sampling locations 
per system under a population-based approach with a plant-based 
approach, using the median and mean number of plants per system given 
in Table V-8 for each of the size categories. For surface water 
systems, the median provides a better indicator of the typical number 
of required sampling locations under the plant-based approach because 
it is much less sensitive to systems with a very large number of 
plants.

                  Table V-9.--Comparison of Monitoring Locations per System Under IDSE for Plant-Based and Population-Based Approaches
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                        Plant-based                     Population-based
                                                                                   ---------------------------------------------------------------------
                                                                                                    Number of monitoring locations per
                                                                         Number of     Number of                  system                    Number of
         Source water type                Population size category        sampling    monitoring   ------------------------------------    monitoring
                                                                          periods    locations per   Based on median    Based on mean     locations per
                                                                                       plant \1\    number of plants  number of plants     system \3\
                                                                                                     per system \2\    per system \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H.........................  0-499..............................          2               2                 2                 3                 2
                                    500-4,999..........................          4               2                 2                 3                 2
                                    5,000-9,999........................          4               2                 2                 3                 4
                                    10,000-24,999......................          6               8                 8                16                 8
                                    25,000-49,999......................          6               8                 8                18                12
                                    50,000-99,999......................          6               8                16                27                16
                                    100,000-499,999....................          6               8                16                24                24
                                    500,000-1,499,000..................  .........  ..............  ................  ................                32
                                    1,500,000-4,999,999................          6               8                32                46                40
                                    =5,000,000..............  .........  ..............  ................  ................                48
Ground Water......................  0-499..............................          2               2                 2                 2                 2
                                    500-9,999..........................          2               2                 2                 4                 2
                                    10,000-99,999......................          4               2                 8                 9                 6
                                    100,000-499,999....................          4               2                 6                20                 8
                                    =500,000................  .........  ..............  ................  ................               12
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ From Table V-5.
\2\ Calculated from the number of locations per plant multiplied by number of plants per system (Table V-8).
\3\ From Table V-4.


            Table V-10.--Comparison of Routine Monitoring Locations per System Under Stage 2B for Plant-Based and Population-Based Approaches
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                       Plant-based                      Population-based
                                                                                  ----------------------------------------------------------------------
                                                                                                    Number of monitoring locations per
                                                                        Frequency     Number of                   system                    Number of
        Source water type               Population size category           of         monitoring   ------------------------------------    monitoring
                                                                       monitoring   locations per    Based on median    Based on mean     locations per
                                                                                      plant \1\     number of plants  number of plants     system \3\
                                                                                                     per system \2\    per system \2\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Subpart H........................  0-499.............................          1                1                  1                 1                 2
                                   500-4,999.........................          4                2                  2                 3                 2
                                   5,000-9,999.......................          4                2                  2                 3                 2
                                   10,000-24,999.....................          4                4                  4                 8                 4
                                   25,000-49,999.....................          4                4                  4                 9                 6
                                   50,000-99,999.....................          4                4                  8                14                 8
                                   100,000-499,999...................          4                4                  8                12                12
                                   500,000-1,499,000.................  ..........  ...............  ................  ................                16
                                   1,500,000-4,999,999...............          4                4                 16                23                20
                                   =5,000,000.............  ..........  ...............  ................  ................                24
Ground Water.....................  0-499.............................          1                1                  1                 1                 2
                                   500-9,999.........................          1                2                  2                 4                 2
                                   10,000-99,999.....................          4                2                  8                 9                 4
                                   100,000-499,999...................          4                2                  6                20                 6
                                   =500,000...............  ..........  ...............  ................  ................                8
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ From Table V-5.
\2\ Calculated from the number of locations per plant multiplied by number of plants per system (Table V-8).
\3\ From Table V-6.


[[Page 49605]]

    Under the population-based approach, the number of required 
sampling locations for systems of different size and source water type 
approximates the number of sampling locations that would be required 
for the majority of systems under the plant-based approach. However, 
systems in the tail ends of the distribution of number of plants per 
system would be required to take more or fewer samples than under the 
plant-based approach. EPA used the median number of plants in a given 
size category as the primary basis for establishing the number of 
monitoring locations for the population-based approach.
    EPA adjusted the number of sampling locations for systems in 
population sizes 25,000 to 49,999, 100,000-499,999, and greater than 
1,500,000 to provide a more even upward trend in proportion to 
population increase. Consistent with the plant-based approach, ground 
water systems serving 10,000 people or greater would be required to 
sample at approximately \1/3\ to \1/2\ the frequency required for 
surface water systems under the population-based approach.
    EPA suggests that the monitoring frequencies for the IDSE and Stage 
2B compliance proposed for consecutive systems that purchase all of 
their finished water year-round (as presented in Tables V-4 and V-6) 
are appropriate for all systems if a population-based approach were 
used in lieu of a plant-based approach in the final rule. EPA believes 
that the population-based approach would ensure more equal and rational 
monitoring requirements among systems serving similar populations than 
the plant-based approach does, while providing generally improved 
representation of DBP occurrence throughout the distribution system. 
Such an approach would simplify implementation and reduce transactional 
costs to States by facilitating determination of the number of sampling 
locations.
    To further evaluate the potential implications of monitoring under 
the population-based approach, EPA has prepared an economic analysis 
addressing monitoring impacts using the population-based approach 
(Economic Analysis for the Stage 2 DBPR, EPA 2003i) and guidance on how 
plant-based monitoring requirements would be affected if a population-
based approach were used instead (Draft IDSE Guidance Manual, EPA 
2003j).
    EPA requests comments on alternative DBP monitoring requirements 
that are population-based versus plant-based; specifically on the 
merits of a population-based monitoring approach for all systems for 
the purpose of addressing the issues raised in this section. 
Specifically:

--Should alternative system size categories be specified under the 
suggested population-based approach?
--What potential issues might be unique for a population-based 
monitoring approach and how might they be addressed?
--Should alternative numbers of monitoring locations or frequencies be 
required in the IDSE or for Stage 2B monitoring?
--Are reduced monitoring requirements adequate to ensure continued 
protection relative to the MCL?
--What are the transition costs and issues associated with moving from 
a plant-based to a population based approach and how might they be 
addressed?

J. Compliance Schedules

1. What is EPA Proposing?
    Today's proposed rule establishes compliance deadlines for public 
water systems to implement the requirements in this rulemaking. EPA is 
proposing a phased strategy for MCLs and simultaneous compliance with 
the LT2ESWTR consistent with the recommendation of the M-DBP Advisory 
Committee and to comply with SDWA requirements for risk balancing. 
Central to the determination of these deadlines is the principle of 
simultaneous compliance between the Stage 2 DBPR and the LT2ESWTR, 
which will ensure continued microbial protection as systems implement 
changes to decrease DBP levels and minimize risk-risk tradeoffs.
    IDSE schedule. Subpart H and ground water systems covered by 
today's proposed rule that serve a population of 10,000 or more must 
submit the results of their IDSE to the primacy agency two years after 
rule promulgation. In addition, wholesale or consecutive systems 
serving fewer than 10,000 that are part of a combined distribution 
system with at least one system serving =10,000 must meet 
this same schedule. These systems must begin IDSE monitoring early 
enough to collect and analyze 12 months of data and prepare an IDSE 
report, which includes recommendations for Stage 2B monitoring 
locations (see section V.H). Subpart H and ground water systems covered 
by today's proposed rule that serve a population of fewer than 10,000 
(except those noted before) must submit the results of their IDSE to 
the primacy agency four years after rule promulgation. These systems 
must begin IDSE monitoring early enough to collect and analyze the data 
and prepare the IDSE report.
    Stage 2A schedule. All systems must comply with the Stage 2A MCLs 
for TTHM and HAA5 three years after rule promulgation.
    Stage 2B schedule. Systems required to submit an IDSE report due 
two years after the rule is promulgated must comply with Stage 2B six 
years after rule promulgation. Subpart H systems required to submit 
IDSE reports four years after rule promulgation and required to do 
Cryptosporidium monitoring under the LT2ESWTR must comply with Stage 2B 
8.5 years after rule promulgation. Small systems not required to 
Cryptosporidium monitoring must be in compliance with Stage 2B 7.5 
years after rule promulgation. Figure V-2 contains several examples of 
how to determine IDSE and Stage 2B compliance dates.

                      Figure V-2. Schedule Examples
------------------------------------------------------------------------
 
-------------------------------------------------------------------------
--Wholesale system (pop. 64,000) with three consecutive systems (pops.
 21,000; 15,000; 5,000):
    --IDSE report due for all systems two years after promulgation since
     wholesale system serves at least 10,000
    --Stage 2B compliance beginning six years after promulgation for all
     systems
--Wholesale system (pop. 4,000) with three consecutive systems (pops.
 21,000; 5,000; 5,000):
    --IDSE report due for all systems two years after promulgation since
     one consecutive system in combined distribution system serves at
     least 10,000
    --Stage 2B compliance beginning six years after promulgation for all
     systems
--Wholesale system (pop. 4,000) with three consecutive systems (pops.
 8,000; 5,000; 5,000):
    --IDSE report due for all systems four years after promulgation
     since no system in combined distribution system exceeds 10,000
     (even though total population exceeds 10,000)
    --Stage 2B compliance beginning 7.5 years after promulgation if no
     Cryptosporidium monitoring under the LT2ESWTR is required or
     beginning 8.5 years after promulgation if Cryptosporidium
     monitoring under the LT2ESWTR is required
------------------------------------------------------------------------


[[Page 49606]]

2. How Did EPA Develop This Proposal?
    EPA is proposing provisions for simultaneous rule compliance with 
the LT2ESWTR to maintain a balance between DBP and microbial risks. 
Simultaneous compliance was mandated by the 1996 SDWA Amendments which 
require that EPA ``minimize the overall risk of adverse health effects 
by balancing the risk from the contaminant and the risk from other 
contaminants, the concentrations of which may be affected by the use of 
a treatment technique or process that would be employed to attain the 
maximum contaminant level'' (Sec. 1412(b)(5)(B)(i)).
    If systems were required to comply with the Stage 2 DBPR prior to 
the LT2ESWTR, systems could lower their disinfectant dose or switch to 
a less effective disinfectant in an attempt to decrease DBP levels. 
This practice could leave segments of the population exposed to greater 
microbial risks. Therefore, simultaneous compliance was a consensus 
recommendation of the Stage 2 M-DBP Advisory Committee to ensure that 
systems would not compromise microbial protection while attempting to 
meet more stringent DBP requirements.
    The Advisory Committee supported the Initial Distribution System 
Evaluation, as discussed in section V.H, and EPA is proposing an IDSE 
schedule consistent with the Advisory Committee's recommendations, in 
which systems are required to submit their IDSE reports to the State 
either two or to four years following rule promulgation. The Advisory 
Committee recommended this to allow enough time for the State to review 
(and revise, if necessary) systems' recommendations for Stage 2B 
monitoring locations and to allow systems three years after completion 
of the State review to comply with Stage 2B MCLs as LRAAs at Stage 2B 
monitoring locations.
    This schedule requires systems serving =10,000 people 
and smaller wholesale and consecutive systems that are part of a 
combined distribution system that includes at least one system serving 
=10,000 to complete IDSE monitoring and prepare and submit 
the IDSE report two years after the rule is finalized. This requirement 
for wholesale systems and consecutive systems serving fewer than 10,000 
that are part of a combined distribution system with at least one 
system serving at least 10,000 to conduct an ``early IDSE'' allows the 
wholesale system to be aware of compliance challenges facing the 
consecutive system and to implement treatment plant capital and 
operational improvements as necessary to ensure compliance. The 
Advisory Committee and EPA both recognized that DBPs, once formed, are 
difficult to remove and are generally best addressed by treatment plant 
improvements.
    While this schedule allows for systems to have the three years to 
comply with Stage 2B following State review of the IDSE report, it 
begins prior to States being required to obtain primacy to implement 
the IDSE. States have two years from promulgation to adopt and 
implement new regulations and may request a two year extension. While 
EPA is preparing to support implementation of those IDSE requirements 
that must be completed prior to States achieving primacy, several 
States have expressed concern about EPA providing guidance and 
reviewing reports from systems that the State has permitted, inspected, 
and worked with for a long time. These States believe that their 
familiarity with the systems enables them to make the best decisions to 
implement the rule and protect public health.
    As specific rule requirements were developed and implementation 
schedules and resource burdens determined, States also expressed 
concerns about the challenges that early implementation posed. In 
response to these concerns, EPA has developed several alternatives to 
the IDSE schedule and provisions that may meet the goals of the IDSE, 
but allow for greater State involvement, lower implementation burden, 
and no delay of the public health protection assured by compliance with 
Stage 2B.
    The first, the ``Alternative IDSE'' option, would delay the 
schedule for each IDSE requirement for two years. Since the compliance 
date for Stage 2B would not be delayed, systems would need to implement 
changes necessary for compliance on a much shorter schedule.
    The second, the ``Concurrent Compliance Monitoring'' option, would 
eliminate the IDSE but require compliance monitoring at an increased 
number of sites during the first year of compliance monitoring as a way 
to identify sites with high DBP levels. This option would reduce 
government oversight and management and, as with other rules, leave 
compliance determinations and preparations to individual systems (with 
guidance available from States). In addition to compliance monitoring 
at Stage 1 DBPR compliance monitoring sites during the first year under 
Stage 2B, systems would also monitor at additional compliance 
monitoring sites equal in number to the IDSE requirement and selected 
using the same criteria that systems use to select IDSE monitoring 
sites. Following one year of concurrent compliance monitoring, the 
system would select routine Stage 2B compliance monitoring locations 
using a protocol similar to the one used to recommend Stage 2B 
compliance monitoring locations in the IDSE report.
    Neither alternative would extend the compliance dates for either 
Stage 2A or Stage 2B. As with the proposed IDSE, systems would be 
eligible for the 40/30 certification approach if all TTHM and HAA5 
compliance monitoring results in the two years prior to the effective 
date were below 0.040 mg/L and 0.030 mg/L, respectively. States would 
be able to grant very small system waivers to systems serving <500 with 
a State finding that Stage 1 DBPR compliance monitoring locations sites 
are adequate to represent both high TTHM and high HAA5 concentrations. 
Table V-11 contains a comparison of the proposed IDSE schedule and the 
schedules for the alternatives.

[[Page 49607]]



                         Table V-11.--Comparison of IDSE and IDSE Alternative Schedules
       [Dates in italics are not in today's proposed rule, but reflect EPA's recommendation and guidance]
----------------------------------------------------------------------------------------------------------------
                                                               ``Alternative IDSE''     ``Concurrent compliance
          Requirement \1\               Today's proposal              option              monitoring'' option
----------------------------------------------------------------------------------------------------------------
IDSE start date for systems =10,000.                          publication.            publication              to conduct concurrent
IDSE start date for systems <10,000  2.5 years after         4.5 years after           compliance monitoring
IDSE report due for systems =10,000.                         2 years after           4 years after             number of samples
IDSE report due for systems <10,000   publication.            publication              required under Stage 1
State review of IDSE report          4 years after           6 years after             plus number under IDSE)
 complete for systems =10,000.                         3 years after           5 years after             compliance monitoring.
State review of IDSE report           publication.            publication              Based on results in first
 complete for systems <10,000.       4.5 years after         6.5 years after           year, system would
                                      publication.            publication              identify routine
                                                                                       compliance monitoring
                                                                                       locations using a
                                                                                       procedure similar to that
                                                                                       in IDSE report and begin
                                                                                       routine monitoring.
Stage 2B compliance for systems =10,000.
Stage 2B compliance for systems            7.5 years after publication if system is not required to conduct
 <10,000.                             Cryptosporidium monitoring; 8.5 years after publication if system required
                                                       to conduct Cryptosporidium monitoring \2\
----------------------------------------------------------------------------------------------------------------
\1\ Systems serving =10,000 also include wholesale systems and consecutive systems serving <10,000
  that are part of a combined distribution system in which at least one system serves =10,000.
\2\ State may grant up to two additional years for capital improvements necessary to comply.

3. Request for Comments
    EPA requests comments on today's proposed compliance schedules. 
Specifically:

--Should EPA promulgate an alternative approach to the IDSE recommended 
in section V.H. that achieves the same goal of identifying Stage 2B 
compliance monitoring locations and does not delay compliance with 
Stage 2B MCLs, but allows for the States to receive primacy and be more 
involved in IDSE implementation? Do either the ``Alternative IDSE'' 
option or the ``Concurrent Compliance Monitoring'' option achieve this 
goal? Does one achieve the goal better than the other? Why? Are there 
either changes to these alternatives or other alternatives not 
presented that achieve this goal?
--Should EPA allow small consecutive systems to meet Stage 2B 
compliance deadlines corresponding to their size (and later than the 
deadlines for their wholesale system) provided they complete their IDSE 
on the same schedule as the wholesale system and provided their water 
quality does not affect the water quality of any other system?

K. Public Notice Requirements

1. What is EPA Proposing?
    SDWA section 1414(c) requires PWSs to provide notice to their 
customers for certain violations or in other circumstances. EPA's 
public notification rule was published on May 4, 2000 (65 FR 25982), 
and is codified at 40 CFR 141.201-141.210 (Subpart Q). Today's proposal 
does not alter the existing TTHM and HAA5 health effects language that 
is required in most public notices under Subpart Q. Because of the 
uncertainties in the health data discussed in section III of today's 
document, EPA is not proposing to include information about 
reproductive and developmental health effects in public notices at this 
time.
2. Request for Comments
    EPA requests comment on the proposed public notification 
requirements, including whether information about the possible 
reproductive or fetal development effects that may be associated with 
high levels of DBPs should be provided.

L. Variances and Exemptions

    States may grant variances in accordance with sections 1415(a) and 
1415(e) of the SDWA and EPA's regulations. States may grant exemptions 
in accordance with section 1416 of the SDWA and EPA's regulations.
1. Variances
    The SDWA provides for two types of variances--general variances and 
small system variances. Under section 1415(a)(1)(A) of the SDWA, a 
State that has primary enforcement responsibility (primacy), or EPA as 
the primacy agency, may grant general variances from MCLs to those 
public water systems of any size that cannot comply with the MCLs 
because of characteristics of the water sources. A variance may be 
issued to a system on condition that the system install the best 
technology, treatment techniques, or other means that EPA finds 
available and based upon an evaluation satisfactory to the State that 
indicates that alternative sources of water are not reasonably 
available to the system. At the time this type of variance is granted, 
the State must prescribe a compliance schedule and may require the 
system to implement additional control measures. Furthermore, before 
EPA or the State may grant a general variance, it must find that the 
variance will not result in an unreasonable risk to health to the 
public served by the public water system. In this proposed rule, EPA is 
specifying BATs for general variances under section 1415(a) (see 
section V.F).
    Section 1415(e) authorizes the primacy agency to issue variances to 
small public water systems (those serving fewer than 10,000 people) 
where the primacy agent determines (1) that the system cannot afford to 
comply with an MCL or treatment technique and (2) that the terms of the 
variances will ensure adequate protection of human health (63 FR 1943-
57; USEPA 1998d). These variances may only be granted where EPA has 
determined that there is no affordable compliance technology and has 
identified a small system variance technology under section 1412(b)(15) 
for the contaminant, system size and source water quality in question. 
As discussed below, small system variances under section 1415(e) are 
not available because EPA has determined that affordable compliance 
technologies are available.
    The 1996 Amendments to the SDWA identify three categories of small 
public water systems that need to be addressed: (1) Those serving a 
population of 3301-10,000; (2) those serving a population of 500-3300; 
and (3) those serving a population of 25-499. The SDWA requires EPA to 
make determinations of available compliance technologies and,

[[Page 49608]]

if needed, variance technologies for each size category. A compliance 
technology is a technology that is affordable and that achieves 
compliance with the MCL and/or treatment technique. Compliance 
technologies can include point-of-entry or point-of-use treatment 
units. Variance technologies are only specified for those system size/
source water quality combinations for which there are no listed 
compliance technologies.
    EPA has completed an analysis of the affordability of DBP control 
technologies for each of the three size categories. Based on this 
analysis, multiple affordable compliance technologies were found for 
each of the three system sizes (USEPA 2003i) and therefore variance 
technologies were not identified for any of the three size categories. 
The analysis was consistent with the methodology used in the document 
``National-Level Affordability Criteria Under the 1996 Amendments to 
the Safe Drinking Water Act'' (USEPA 1998g) and the ``Variance 
Technology Findings for Contaminants Regulated Before 1996'' (USEPA 
1998h).
2. What Are the Affordable Treatment Technologies for Small Systems?
    The treatment trains considered and predicted to be used in EPA's 
compliance forecast for systems serving under 10,000 people, are listed 
in Table V-12.

    Table V-12.--Technologies Considered and Predicted To Be Used in
          Compliance Technology Forecast for Small Systems \1\
------------------------------------------------------------------------
            SW water plants                      GW water plants
------------------------------------------------------------------------
[sbull] Switching to chloramines as a    [sbull] Switching to
 residual disinfectant.                   chloramines as a residual
[sbull] Chlorine dioxide (Not for         disinfectant
 systems serving fewer than 100 people). [sbull] UV
[sbull] UV.............................  [sbull] Ozone (not for systems
[sbull] Ozone (not for systems serving    serving fewer than 100 people)
 fewer than 100 people).                  \2\
[sbull] Micro-filtration/Ultra-          [sbull] GAC20 \2\
 Filtration \2\.                         [sbull] Nanofiltration \2\
[sbull] GAC20 \2\......................
[sbull] GAC20 + Advanced disinfectants.
[sbull] Membranes (Micro-Filtration/
 Ultra-Filtration + Nanofiltration).
------------------------------------------------------------------------
\1\ Based on exhibits 6.8a and 6.8b in Economic Analysis for the
  proposed Stage 2 DBPR (USEPA 2003i)
\2\ Italicized technologies are those predicted to be used in the
  compliance forecast.

    The household costs for these technologies were compared against 
the national-level affordability criteria to determine the affordable 
treatment technologies. The Agency's national-level affordability 
criteria were published in the August 6, 1998 Federal Register (USEPA 
1998g). In this document, EPA discussed the procedure for affordable 
treatment technology determinations for the contaminants regulated 
before 1996.
    The following section provides a description of how EPA derived the 
national-level affordability criteria pertinent to this rule. First, 
EPA calculated an ``affordability threshold'' (i.e., the total annual 
household water bill that would be considered affordable). The total 
annual water bill includes costs associated with water treatment, water 
distribution, and operation of the water system. In developing the 
threshold of 2.5% median household income, EPA considered the 
percentage of median household income spent by an average household on 
comparable goods and services and on cost comparisons with other risk 
reduction activities for drinking water such as households purchasing 
bottled water or a home treatment device. The complete rationale for 
EPA's selection of 2.5% as the affordability threshold is described in 
``Variance Technology Findings for Contaminants Regulated Before 1996'' 
(USEPA 1998h).
    The Variance Technology Findings document also describes the 
derivation of the baselines for median household income, annual water 
bills, and annual household consumption. Data from the Community Water 
System Survey (CWSS) were used to derive the annual water bills and 
annual water usage values for each of the three small system size 
categories. The data on zip codes were used with the 1990 Census data 
on median household income to develop the median household income 
values for each of the three small-system size categories. The median 
household-income values used for the affordable technology 
determinations are not based on the national median income. The value 
for each size category is a national median income for communities 
served by small water systems within that range. Table V-13 presents 
the baseline values for each of the three small-system size categories. 
Annual water bills are based on 1995 estimates (USEPA 1998h) and 
adjusted upward for anticipated costs attributed to new drinking water 
regulations since 1995, i.e., the IESWTR, Stage 1 DBPR, Filter Backwash 
Recycling Rule, Arsenic Rule, LT1ESWTR, Public Notification Rule, and 
Consumer Confidence Rule.\1\ Median household income estimates are 
based on estimates made in 1995 (USEPA 1998h) and adjusted upward for 
inflation to represent 2000 incomes (USEPA 2003i).
---------------------------------------------------------------------------

    \1\ EPA is currently receiving input from a National Drinking 
Water Advisory Council (NDWAC). This process is expected to conclude 
in the fall of 2003 with a report that will be sent by the NDWAC. 
EPA has also received a report from the Science Advisory Board's 
Environmental Economics Advisory Committee on its review of the 
national-level affordability criteria (USEPA 2002c). One of the 
charges given to both groups was to evaluate the process used by EPA 
to adjust the baseline water bills to account for costs attributable 
to regulations promulgated after 1996. Because the Stage 2 DBPR 
affordability analysis is being conducted before EPA can complete a 
comprehensive reassessment of affordability, today's estimate for 
the increase to the average water bill to account for regulations 
after 1996 reflects existing Agency affordability criteria and 
methodology. This estimate may change in the future.

[[Page 49609]]



    Table V-13.--Baseline Values for Small Systems Categories and Available Expenditure Margin for Affordable
                                            Technology Determinations
----------------------------------------------------------------------------------------------------------------
                                         Annual HH                                                  Available
                                        consumption    Median HH   2.5% median   Current annual    expenditure
 System size category (pop. served)    (1000 gallons/    income   HH income(s)  water bills  ($/  margin ($/hh/
                                            yr)           ($)                         yr)             year)
----------------------------------------------------------------------------------------------------------------
25-500..............................              72      35,148          878              290              588
501-3,300...........................              74      30,893          772              230              542
3,301-10,000........................              77      31,559          789              219              570
----------------------------------------------------------------------------------------------------------------

    For each size category, the threshold value was determined by 
multiplying the median household income by 2.5 percent. The annual 
household water bills were subtracted from this value to obtain the 
available expenditure margin. Projected treatment costs were compared 
against the available expenditure margin to determine if there were 
affordable compliance technologies for each size category. The 
available expenditure margin for the three size categories is presented 
in Table V-13.
    The size categories specified in SDWA for affordable technology 
determinations are different from the size categories typically used by 
EPA in the Economic Analysis. A weighted average procedure was used to 
derive design and average flows for the 25-500 category using design 
and average flows from the 25-100 and 101-500 categories. A similar 
approach was used to derive design and average flows from the 501-1000 
and 1001-3300 categories for the 501-3300 category. The Variance 
Technology Findings document (USEPA 1998h) describes this procedure in 
more detail. Table V-14a lists the design and average flows for the 
three size categories.

    Table V-14a.--Design and Average Daily Flows Used for Affordable
                        Technology Determinations
------------------------------------------------------------------------
                                            Design flow    Average flow
System size category (population served)       (mgd)           (mgd)
------------------------------------------------------------------------
25-500..................................           0.058           0.015
501-3,300...............................           0.50            0.17
3,301-10,000............................           1.8             0.70
------------------------------------------------------------------------

    Capital and operating and maintenance costs were derived for each 
treatment technology used in the compliance forecast for small systems 
using the flows listed previously and the cost equations in the 
Technology and Cost Document (USEPA 2003k). Capital costs were 
amortized using the 7 percent interest rate preferred by Office of 
Management and Budget (OMB) for benefit-cost analyses of government 
programs and regulations rather than a 3 percent interest rate.
    The annual system treatment cost in dollars per year was converted 
into a rate increase using the average daily flow. The annual water 
consumption values listed in Table V-13 were multiplied by 1.15 to 
account for water lost due to leaks. Since the water lost to leaks is 
not billed, the water bills for the actual water used were adjusted to 
cover this lost water by increasing the household consumption. The rate 
increase in dollars per thousand gallons used was multiplied by the 
adjusted annual consumption to determine the annual cost increase for 
the household for each treatment technology.
    With very few exceptions, the household costs for all predicted 
compliance technologies in Table V-12 are below the available 
expenditure margin. The only technology that was predicted to be used 
in the compliance forecast for the Stage 2 DBPR and that costs slightly 
more than the available expenditure margin is GAC20 (240 day carbon 
replacement) with advanced disinfectants for systems serving 500 people 
or fewer. As shown in the Economic Analysis (USEPA 2003i), 13 systems 
(less than 1 percent) among systems serving fewer than 500 people are 
predicted to use GAC20 with advanced disinfection to comply with the 
proposed Stage 2 DBPR. However, alternate affordable technologies are 
available. Thus, EPA believes that compliance by these systems will be 
affordable. In some cases, the compliance data for these systems under 
the Stage 2 DBPR is the same as under the Stage 1 DBPR (because many 
systems serving fewer than 500 people will have the same single 
sampling site under both rules); these systems will have already 
installed the necessary compliance technology to comply with the Stage 
1 DBPR. It is also possible that less costly technologies such as those 
for which percentage use caps were set in the decision tree may 
actually be used to achieve compliance (e.g., chloramines, UV).
    As shown in Table V-14b, the cost model (USEPA 2003i) predicts that 
households served by very small systems will experience household cost 
increases greater than the available expenditure margins as a result of 
adding advanced technology for the Stage 2 DBPR. This prediction is 
probably overestimated because small systems have other compliance 
alternatives available to them besides adding treatment. For example, 
some of these systems currently may be operated on a part-time basis; 
therefore, they may be able to modify the current operational schedule 
or use excessive capacity to avoid installing a costly technology to 
comply with the Stage 2 DBPR. The system also may identify another 
water source that has lower TTHM and HAA5 precursor levels. Systems 
that can identify such an alternate water source may not have to treat 
that new source water as intensely as their current source, resulting 
in lower treatment costs. Systems may elect to connect to a neighboring 
water system. While connecting to another system may not be feasible 
for some remote systems, EPA estimates that more than 22 percent of all 
small water systems are located within metropolitan regions (USEPA 
2000c) where distances between neighboring systems will not present a 
prohibitive barrier. More discussion of household cost increases is 
presented in a later section (Section VII) and the Economic Analysis 
(USEPA 2003i).

[[Page 49610]]

[GRAPHIC] [TIFF OMITTED] TP18AU03.009

    EPA is currently reviewing its national-level affordability 
criteria, and has solicited recommendations from both the NDWAC and the 
SAB as part of this review. If the national-level affordability 
criteria are revised prior to promulgation of the final Stage 2 DBPR, 
EPA may reevaluate the affordability of the identified small system 
compliance technologies based on the revised criteria and may revise 
its determination of whether to list any variance technologies as a 
result. EPA requests comment on the application of its affordability 
criteria in this rulemaking and on its determination that there are 
affordable small system compliance technologies for all three statutory 
small system size categories.

M. Requirements for Systems To Use Qualified Operators

    EPA believes that systems that must make treatment changes to 
comply with requirements to reduce microbiological risks and risks from 
disinfectants and disinfection byproducts should be operated by 
personnel who are qualified to recognize and respond to problems. 
Subpart H systems were required to be operated by qualified operators 
under the SWTR (40 CFR 141.70). The Stage 1 DBPR added requirements for 
all disinfected systems to be operated by qualified personnel who meet 
the requirements specified by the State, which may differ based on 
system size and type. The rule also required that States maintain a 
register of qualified operators (40 CFR 141.130(c)). While the proposed 
Stage 2 DBPR requirements do not supercede or modify the requirement 
that disinfected systems be operated by qualified personnel, the Stage 
2 DBPR re-emphasizes the important role that qualified operators play 
in delivering safe drinking water to the public. States should also 
review and modify, as required, their qualification standards to take 
into account new technologies (e.g., ultraviolet (UV) disinfection) and 
new compliance requirements (including simultaneous compliance and 
consecutive system requirements).

N. System Reporting and Recordkeeping Requirements

1. Confirmation of Applicable Existing Requirements
    Today's proposed Stage 2 DBPR, consistent with the current system 
reporting regulations under 40 CFR 141.131, requires public water 
systems to report monitoring data to States within ten days after the 
end of the compliance period. In addition, systems are required to 
submit the data required in Sec.  141.134. These data are required to 
be submitted quarterly for any monitoring conducted quarterly or more 
frequently, and within ten days of the end of the monitoring period for 
less frequent monitoring.
2. Summary of Additional Reporting Requirements
    EPA proposes that two years after rule promulgation, systems 
serving 10,000 or more people (plus consecutive systems that are part 
of a combined distribution system with a system serving at least 
10,000) be required to report the results of their IDSE to their State, 
unless the State has waived this requirement for systems serving fewer 
than 500. Systems are also required to report to the State recommended 
long-term (Stage 2B) compliance monitoring sites as part of the IDSE 
report. While the IDSE options discussed in section V.J. would delay 
the timing of this requirement, EPA believes that the burden would not 
change.
    Beginning three years after rule promulgation, systems must report 
compliance with Stage 2A MCLs based on LRAAs (0.120 mg/L TTHM and 0.100 
mg/HAA5), as well as continue to report compliance with 0.080 mg/L TTHM 
and 0.060 mg/L HAA5 as RAAs. Systems must report compliance with the 
Stage 2B TTHM and HAA5 MCLs (0.080 mg/L TTHM and 0.060 mg/L HAA5 as 
LRAAs) according to the compliance schedules outlined in section V.J. 
of today's proposal. Reporting for DBP monitoring, as described 
previously, will remain generally consistent with current public water 
system reporting requirements (Sec.  141.31 and Sec.  141.134); systems 
will be required to calculate and report each LRAA (instead of the 
system's RAA) and each individual monitoring result (as required under 
the Stage 1 DBPR). Systems will also be required to consult with the 
State about each peak excursion event no later than the next sanitary 
survey for the system, as discussed in section V.E.
3. Request for Comment
    EPA requests comment on all system reporting and recordkeeping 
requirements.

O. Analytical Method Requirements

1. What Is EPA Proposing Today?
    The Stage 2 DBPR proposed today does not add any new disinfectants 
or disinfection byproducts to the list of contaminants currently 
covered by MRDLs or MCLs. However, additional methods have become 
available since the analytical methods in the Stage 1 DBPR were 
promulgated (USEPA 1998c). EPA is proposing to add to 40 CFR 141.131 
one method for chlorine dioxide and chlorite, one method for HAA5 which 
can also be used to analyze for the regulated contaminant dalapon, 
three methods for bromate, chlorite, and bromide, one method for 
bromate only, and one method for total

[[Page 49611]]

organic carbon (TOC) and specific ultraviolet absorbance (SUVA). One of 
the methods that is currently approved for bromate, chlorite, and 
bromide can be used to determine chloride, fluoride, nitrate, nitrite, 
orthophosphate, and sulfate, so EPA is proposing to add it as an 
approved method for those contaminants in 40 CFR 141.23 and 40 CFR 
143.4. EPA is also proposing to add the HAA5 method that includes 
dalapon to 40 CFR 141.24 for dalapon compliance monitoring.
    Several of the methods that were promulgated with the Stage 1 DBPR 
have been included in publications that were issued after December 
1998. EPA is proposing to approve the use of the recently published 
versions of three methods for determining free, combined, and total 
chlorine residuals, two methods for total chlorine only, one method for 
free chlorine only, one method for chlorite and chlorine dioxide, one 
method for chlorine dioxide only, one method for HAA5, three methods 
for TOC and dissolved organic carbon (DOC), and one method for 
ultraviolet absorption at 254nm (UV 254). EPA is proposing 
to update the citation for one method for bromate, chlorite, and 
bromide.
    EPA is also proposing to standardize the HAA5 sample holding times 
and the bromate sample preservation procedure and holding time. EPA is 
clarifying which methods are approved for magnesium hardness 
determinations in 40 CFR 141.131 and 40 CFR 141.135.
    Analytical methods that are proposed for approval or for which 
changes are proposed in today's rule are summarized in Table V-15 and 
are described in more detail later in this section.

                       Table V-15.--Analytical Methods Addressed in Today's Proposed Rule
----------------------------------------------------------------------------------------------------------------
            Analyte                      EPA method               Standard method 1               Other
----------------------------------------------------------------------------------------------------------------
         Sec.   141.23
Fluoride.......................  300.1                       ..........................  .......................
Nitrate........................  300.1                       ..........................  .......................
Nitrite........................  300.1                       ..........................  .......................
Orthophosphate.................  300.1                       ..........................  .......................
         Sec.   141.24
Dalapon........................  552.3                       ..........................  .......................
 Sec.   141.131--Disinfectants
Chlorine (free, combined,        ..........................  4500-Cl D
 total).
                                 ..........................  4500-Cl F
                                 ..........................  4500-Cl G
(total)                          ..........................  4500-Cl E
                                 ..........................  4500-Cl I
(free)                           ..........................  4500-Cl H
Chlorine Dioxide...............  327.0                       4500-ClO 2 D
                                                             4500-ClO 2 E
  Sec.   141.131--Disinfection
           Byproducts
HAA5...........................  552.1 2                     6251 B 2                    .......................
                                 552.3
Bromate........................  300.1 3                     ..........................  ASTM D 6581-00
                                 317.0 Revision 2
                                 321,8 4
                                 326.0
Chlorite (monthly or daily)....  300.1 3                     ..........................  ASTM D 6581-00
                                 317.0 Revision 2
                                 326.0
(daily)........................  327.0                       4500-ClO 2 E                .......................
     Sec.   141.131--Other
           parameters
Bromide........................  300.1 3                     ..........................  ASTM D 6581-00
                                 317.0 Revision 2
                                 326.0
TOC/DOC........................  415.3                       5310 B
                                                             5310 C
                                                             5310 D
UV 254.........................  415.3                       5910 B                      .......................
SUVA...........................  415.3                       ..........................  .......................
          Sec.   143.4
Chloride.......................  300.1                       ..........................  .......................
Sulfate........................  300.1                       ..........................  .......................
----------------------------------------------------------------------------------------------------------------
1 EPA is proposing to cite both the 20th edition and the 2003 On-Line Version of Standard Methods for the
  Examination of Water and Waste Water in addition to the currently cited 19th editions for all methods listed
  in this column with the exception of 4500-ClO2 D for chlorine dioxide which is not available in the 2003 On-
  Line Version.
2 EPA is proposing to change the sample holding time to 14 days.
3 EPA is proposing to update the citation.
4 EPA is proposing that samples be preserved with 50 mg ethylenediamine/L and analyzed within 28 days.

2. How Was This Proposal Developed?
    EPA evaluated the performance of the new methods for their 
applicability to compliance monitoring. The primary purpose of this 
evaluation was to determine if the new methods provide data of 
comparable or better quality than the methods that are currently 
approved. Methods currently approved for DBPs were also examined to 
determine applicability to other regulated contaminants.
    EPA reviewed the new publications of methods from consensus 
organizations such as Standard Methods and American Society for Testing 
and Materials (ASTM). As a result, EPA identified one new method from 
ASTM

[[Page 49612]]

which is suitable for compliance monitoring. EPA also determined that 
the newer editions of Standard Methods did not change the individual 
methods approved under the Stage 1 DBPR.
3. Which New Methods Are Proposed for Approval?
    a. EPA Method 327.0 for chlorine dioxide and chlorite. EPA is 
proposing to add a new method for the measurement of chlorine dioxide 
residuals and daily chlorite concentrations. EPA Method 327.0 (USEPA 
2003q) is an enzymatic/spectrophotometric method in which a total 
chlorine dioxide plus chlorite concentration is determined in an 
unsparged sample and the chlorite concentration is determined in a 
sparged sample. The chlorine dioxide concentration is then calculated 
by subtracting the chlorite concentration from the total.
    The pH of the samples (sparged and unsparged) and blank are 
adjusted to 6.0 with a citric acid/glycine buffer. The chromophore 
Lissamine Green B (LGB) and the enzyme horseradish peroxidase are 
added. The enzyme reacts with the chlorite in the sample to form 
chlorine dioxide which then reacts with the chromophore LGB to reduce 
the absorbance at 633nm of the sample. The absorbance of the samples 
and blank are determined spectrophotometrically. The difference in 
absorbance between the samples and the blank is proportional to the 
chlorite and total chlorine dioxide/chlorite concentrations in the 
samples.
    EPA Method 327.0 offers advantages over the currently approved 
methods in that it is not subject to positive interferences from other 
chlorine species and it is easier to use.
    The single laboratory detection limits presented in the method are 
0.08-0.11 mg/L for chlorite and 0.04-0.16 mg/L for chlorine dioxide. 
The detection limits are based on the analyses of sets of seven 
replicates of reagent water that were fortified with low concentrations 
of chlorite with and without the presence of chlorine dioxide and low 
concentrations of chlorine dioxide with and without the presence of 
chlorite. The standard deviation of the mean concentration for each set 
of samples was calculated and multiplied by the student's t-value at 
99% confidence and n-1 degrees of freedom (3.143 for 7 replicates) to 
determine the detection limit. The accuracy reported in the method for 
laboratory fortified blanks at concentrations of 0.2-1.0 mg/L is 103-
118 % for chlorite and 102-124 % for chlorine dioxide with relative 
standard deviations between 2.9 and 16 %. Replicate analyses of 
drinking water samples from surface and ground water sources fortified 
at concentrations of approximately 1 and 2 mg/L chlorite and chlorine 
dioxide showed average recoveries of 91-110 % with relative standard 
deviations of 1-9 %.
    EPA is proposing to approve EPA Method 327.0 as an additional 
method for monitoring chlorine dioxide and for making the daily 
determination of chlorite at the entry point to the distribution 
system. It will provide water systems with additional flexibility in 
monitoring the application of chlorine dioxide. EPA believes that many 
water plant operators will prefer the new method over the currently 
approved methods due to its ease of use.
    b. EPA Method 552.3 for HAA5 and dalapon. EPA is proposing to add a 
new method (EPA Method 552.3) for HAA5 that provides comparable 
sensitivity, accuracy, and precision to the previously approved 
methods. EPA Method 552.3 (USEPA 2003p) has the added benefit of 
allowing laboratories to more easily measure four additional haloacetic 
acids (bromochloroacetic acid, bromodichloroacetic acid, 
chlorodibromoacetic acid, and tribromoacetic acid) at the same time the 
HAA5 compounds are being measured, without compromising the quality of 
data for the HAA5 compounds. Of the currently approved methods for 
HAA5, only EPA Method 552.2 (USEPA 1995) provides method performance 
data for all of these additional compounds, but the reaction conditions 
must be carefully controlled. EPA believes that analyses for these 
additional HAAs can be accomplished more easily without compromising 
the quality of data for the HAA5 compounds by using EPA Method 552.3.
    EPA Method 552.3 for HAA5, other haloacetic acids, and the 
regulated contaminant dalapon allows two extraction options. The first 
option involves an acidic extraction with methyl tertiary butyl ether 
(MTBE) which is the same solvent used in the currently approved HAA5 
methods. The analytes (HAA5, other HAAs, and dalapon) are then 
converted to their methyl esters by the addition of acidic methanol to 
the extract followed by heating. The amount of acidic methanol that is 
added to the extract is increased in the new method resulting in 
increased methylation efficiency for some of the analytes. The 
increased methylation efficiency is significant for the additional HAAs 
and thus provides greater sensitivity, precision, and accuracy for them 
when compared to EPA Method 552.2. The acidic extract is neutralized 
with a saturated solution of sodium bicarbonate and the target analytes 
are identified and measured by gas chromatography using electron 
capture detection (GC/ECD).
    The second option in the new EPA Method 552.3 involves an acidic 
extraction with tertiary amyl methyl ether (TAME). The HAAs are then 
converted to their methyl esters by the addition of acidic methanol to 
the extract followed by heating. The use of TAME instead of MTBE as the 
extraction solvent allows the use of a higher temperature during the 
methylation process. This increases the methylation efficiency and thus 
provides significant increases in sensitivity, precision, and accuracy 
for the additional HAAs. The acidic extract is neutralized with a 
saturated solution of sodium bicarbonate and the target analytes are 
identified and measured by gas chromatography using electron capture 
detection (GC/ECD).
    The performance of EPA Method 552.3 is comparable to the currently 
approved methods for determining the HAA5 analytes. A comparison of the 
performance of EPA Method 552.3 to the currently approved HAA5 methods 
is shown in Table V-16. The data are taken from the individual methods, 
so the precision, accuracy, and detection data were not generated using 
the same samples or by the same laboratory.

                               Table V-16.--Performance of Haloacetic Acid Methods
----------------------------------------------------------------------------------------------------------------
                  QC Parameter                       MCAA         DCAA         TCAA         MBAA         DBAA
----------------------------------------------------------------------------------------------------------------
Precision (Max %RSD in fortified drinking water
                  samples) \1\
EPA 552.1......................................           15           14           28           11            7
EPA 552.2......................................           13            6           15            6            5
EPA 552.3 (MTBE option)........................            6            4            1            4            5
EPA 552.3 (TAME option)........................           10            4            2            4            5
SM 6251 B......................................            8            7            6            8            7

[[Page 49613]]

 
  Accuracy (Range of % Recoveries in fortified
          drinking water samples) \2\
EPA 552.1......................................       76-100       75-126       56-106        86-97       94-103
EPA 552.2......................................        84-97       96-105        62-82       86-100       72-112
EPA 552.3 (MTBE option)........................       98-126       96-103       89-100       99-113      101-111
EPA 552.3 (TAME option)........................       97-131       97-107       89-103           99      101-105
SM 6251 B......................................       99-103       96-103      100-103       97-101          102
         Detection Limit ([mu]g/L) \3\
EPA 552.1......................................         0.21         0.45         0.07         0.24         0.09
EPA 552.2......................................         0.27         0.24         0.08         0.20         0.07
EPA 552.3 (MTBE option)........................         0.17         0.02         0.02         0.03         0.01
EPA 552.3 (TAME option)........................         0.20         0.08         0.02         0.13         0.02
SM 6251 B......................................         0.08         0.05         0.05         0.09        0.06
----------------------------------------------------------------------------------------------------------------
\1\ The highest relative standard deviation (%RSD) for replicate analyses of fortified drinking water samples as
  shown in each method.
\2\ The range of recoveries reported for replicate analyses of fortified drinking water samples as shown in each
  method.
\3\ The detection limit as determined by analyzing seven or more replicates of reagent water that is fortified
  with low concentrations of the haloacetic acids. The standard deviation of the mean concentration for each
  analyte is calculated and multiplied by the student's t-value at 99% confidence and n-1 degrees of freedom
  (3.143 for 7 replicates).

    Two of the currently approved HAA5 methods (EPA Methods 552.1 
(USEPA 1992) and 552.2 (USEPA 1995)) are also approved for analyses of 
water samples for the regulated contaminant dalapon, a synthetic 
organic chemical. The new HAA5 method can also be used to determine 
dalapon in drinking water. As shown in Table V-17, both solvent options 
in EPA Method 552.3 provide comparable or better method performance 
than the approved methods.

                                   Table V-17.--Performance of Dalapon Methods
----------------------------------------------------------------------------------------------------------------
                                                                                                 EPA 552.3
          Dalapon performance characteristic               EPA 552.1        EPA 552.2    -----------------------
                                                                                             MTBE        TAME
----------------------------------------------------------------------------------------------------------------
Precision\1\ (% RSD)..................................              14               11           2           4
Accuracy\2\ (% Recovery)..............................          88-102           86-100      98-112      87-103
Detection Limit\3\ ([mu]g/L)..........................            0.32             0.12        0.02       0.14
----------------------------------------------------------------------------------------------------------------
\1\ The highest relative standard deviation (%RSD) for replicate analyses of fortified drinking water samples as
  shown in each method.
\2\ The range of recoveries reported for replicate analyses of fortified drinking water samples as shown in each
  method.
\3\ The detection limit as determined by analyzing seven or more replicates of reagent water that is fortified
  with low concentrations of dalapon. The standard deviation of the mean dalapon concentration is calculated and
  multiplied by the student's t-value at 99% confidence and n-1 degrees of freedom (3.143 for 7 replicates).

    EPA is proposing to approve EPA Method 552.3 for dalapon (Sec.  
141.24(e)(1)) in addition to HAA5 even though dalapon is not a 
contaminant that is addressed in this proposed rule. EPA believes that 
extending approval to all the regulated contaminants covered by the 
method provides more flexibility to laboratories. It allows the 
laboratories the option of reducing the number of methods that they 
need to keep in operation for their clients, because the new method can 
be used for dalapon and HAA5 compliance monitoring samples and for 
determining the additional HAAs for non-regulatory purposes. EPA 
recognizes that laboratories will probably not be determining dalapon 
concentrations for compliance purposes in the same samples as used for 
HAA5 compliance monitoring. However, EPA believes allowing the same 
method to be used even if the samples are not the same is more cost 
effective for laboratories, because switching between methods results 
in increased analyst and instrument time. EPA is not proposing to 
withdraw the other dalapon methods, because that would reduce 
flexibility for the laboratories and place an unnecessary burden on 
laboratories that do not need to use EPA Method 552.3.
    c. ASTM D 6581-00 for bromate, chlorite, and bromide. ASTM Method D 
6581-00 (ASTM 2002) for the determination of bromate, chlorite, and 
bromide was adopted by ASTM in 2000. This method uses the same 
procedures as EPA Method 300.1 (USEPA 2000l) (the method promulgated in 
the Stage 1 DBPR) and thus is considered equivalent to the approved 
method (Hautman et al. 2001). The ASTM method includes interlaboratory 
study data that were not available when EPA Method 300.1 was published. 
The study data demonstrate good precision and low bias for all 
analytes.
    Under section 12(d) of the National Technology Transfer and 
Advancement Act, the Agency is directed to consider whether to use 
voluntary consensus standards in its regulatory activities. ASTM Method 
D 6581-00 is an acceptable consensus standard and it is published in 
the 2001, 2002, and 2003 editions of The ASTM Annual Book of Standards. 
EPA is proposing to approve ASTM Method D 6581-00 in order to provide 
additional flexibility to laboratories. Any edition containing the 
cited version may be used.
    d. EPA Method 317.0 revision 2 for bromate, chlorite, and bromide. 
EPA Method 317.0 Revision 2 (USEPA 2001d) is an extension of the 
currently approved EPA Method 300.1 for bromate, chlorite, and bromide. 
It uses the EPA Method 300.1 technology, but it adds a postcolumn 
reactor that provides a more sensitive and specific analysis for 
bromate than is obtained using EPA Method 300.1. As with EPA Method 
300.1, the anions are separated by ion chromatography and detected 
using a conductivity detector. (Bromate, chlorite, and bromide 
concentrations determined by the conductivity detector are equivalent 
to those measured using EPA Method 300.1.) After the sample

[[Page 49614]]

passes through the conductivity detector, it enters a postcolumn 
reactor chamber in which o-dianisidine dihydrochloride (ODA) is added 
to the sample. This compound forms a chromophore with the bromate that 
is present in the sample and the chromophore concentration is 
determined using a ultraviolet/visible (UV/Vis) absorbance detector. 
There are several advantages of this method:
    (1) Very few ions react with ODA to form compounds that are 
detected by the UV/Vis detector. This makes the method less susceptible 
to interferences for bromate.
    (2) The UV/Vis detector is very sensitive to the chromophore, so 
lower concentrations of bromate can be detected and quantitated. 
(Bromate concentrations can be reliably quantitated as low as 1 [mu]g/L 
using this detector versus 5 [mu]g/L for EPA Method 300.1.)
    (3) Since the front part of the analysis is the same as EPA Method 
300.1, bromate, chlorite, and bromide can be determined in the same 
analysis.
    The first version of this method, EPA Method 317.0 has been 
evaluated in a multiple laboratory study (Wagner et al. 2001; Hautman 
et al. 2001). The results from the study indicate high precision and 
very low bias in data generated using this method. The interlaboratory 
precision for bromate, chlorite, and bromide using the conductivity 
detector and bromate using the UV/Vis detector are 12%, 4.2%, 6.9%, and 
9.6% relative standard deviation (RSD), respectively. The 
interlaboratory bias for bromate, chlorite, and bromide using the 
conductivity detector and bromate using the UV/Vis detector are 0.35%, 
-0.98%, -0.87%, and 4.8%, respectively. The average detection levels 
for bromate, chlorite, and bromide using the conductivity detector and 
bromate using the UV/Vis detector are 2.2, 1.6, 2.8, and 0.24 [mu]g/L, 
respectively.
    Subsequent to the interlaboratory study of EPA Method 317.0, a 
problem with ODA was discovered. The purity of the reagent can vary 
from lot to lot and this affects the performance of the method. EPA has 
evaluated the method performance using ODA obtained from several 
commercial sources and from different lots from the same supplier. 
Based on that new information, EPA revised Method 317.0 to document how 
to detect and correct problems that can result from a contaminated ODA 
supply. The revised method is designated EPA Method 317.0 Revision 2.0 
and this is the version that is being proposed today. The performance 
of the revised method is identical to the original version.
    EPA believes EPA Method 317.0 Revision 2.0 should be approved as an 
additional method for bromate, chlorite, and bromide compliance 
monitoring. EPA anticipates that water systems will prefer to have 
their bromate samples analyzed by this new method, because it provides 
higher quality data than the currently approved method when bromate 
concentrations are below the MCL of 0.010 mg/L (10 [mu]g/L). Only a few 
laboratories are currently performing analyses using the postcolumn 
reactor technology included in the method, but the number is increasing 
as more laboratories become aware of the advantages.
    e. EPA Method 326.0 for bromate, chlorite, and bromide. EPA Method 
326.0 (USEPA 2002a) is based on the procedure reported by Salhi and von 
Gunten (1999) and uses an approach that is similar to EPA Method 317.0 
Revision 2.0. The method involves the separation of the anions 
(bromate, chlorite, and bromide) following the scheme outlined in EPA 
Methods 300.1 and 317.0 Revision 2.0. (Bromate, chlorite, and bromide 
data from the conductivity detector are equivalent to data generated 
using EPA Method 300.1.) The eluent stream exiting the conductivity 
detector is mixed with a postcolumn reagent consisting of an acidic 
solution of potassium iodide with a catalytic concentration of 
molybdenum (VI). Bromate reacts with the iodide to form triiodide which 
is measured by its UV absorption at 352 nm.
    EPA Method 326.0 has similar accuracy, precision, and sensitivity 
for bromate compared to EPA Method 317.0 Revision 2.0. Thirty drinking 
water samples fortified with 1-7 [mu]g bromate/L were analyzed using 
both methods. Accuracy, expressed as % recovery, ranged from 78.0 to 
129% for both methods and precision, expressed as % RSD ranged from 3.7 
to 13.5% (Wagner et al. 2002). The detection limit of EPA Method 326.0 
is 0.17 [mu]g/L as determined by analyzing seven or more replicates of 
reagent water that is fortified with low concentrations of bromate. The 
standard deviation of the mean bromate concentration is calculated and 
multiplied by the student's t-value at 99% confidence and n-1 degrees 
of freedom (3.143 for 7 replicates).
    EPA is proposing EPA Method 326.0 as an additional method for 
bromate, chlorite, and bromide compliance monitoring. It provides 
higher quality bromate data than the currently approved EPA Method 
300.1 when bromate concentrations are below 10 [mu]g/L. EPA anticipates 
the number of laboratories using this method will increase as utilities 
become aware of the method's sensitivity and begin to request it be 
used for their samples.
    f. EPA Method 321.8 for bromate. EPA is proposing to add EPA Method 
321.8 (USEPA 2000d) specifically for bromate compliance monitoring. It 
involves an ion chromatograph coupled to an inductively coupled plasma 
mass spectrometer (IC/ICP-MS). The ion chromatograph separates bromate 
from other ions present in the sample and then bromate is detected and 
quantitated by the ICP-MS. Mass 79 is used for quantitation while mass 
81 provides isotope ratio information that can be used to screen for 
potential polyatomic interferences. The advantage of this method is 
that it is very specific and sensitive to bromate. The single 
laboratory detection limit presented in the method is 0.3 [mu]g/L. The 
average accuracy reported in the method for laboratory fortified blanks 
is 99.8% recovery with a three sigma control limit of 10.2%. Average 
accuracy and precision in fortified drinking water samples are reported 
as 97.8% recovery and 2.9% relative standard deviation, respectively.
    During the Information Collection Rule, thirty-three samples were 
analyzed by this method in addition to the selective anion 
concentration (SAC) method used by EPA for the low-level bromate 
analyses. EPA Method 321.8 provided comparable data to that generated 
by the SAC method (Fair 2002).
    EPA Method 321.8 has undergone second laboratory validation (Day et 
al. 2001) and the results indicate the method can be successfully 
performed in non-EPA laboratories. The calculated detection limit 
determined by the second laboratory is 0.4 [mu]g/L. The average 
accuracy achieved for laboratory fortified blanks at 5 [mu]g/L is 93% 
recovery with a relative standard deviation of 8.9%. Average accuracy 
and precision in fortified drinking water samples are reported as 101% 
recovery and 9% relative standard deviation, respectively.
    The IC/ICP-MS instrumentation used in EPA Method 321.8 is a new 
technology in the drinking water laboratory community. Even though the 
technology is not yet widely used, EPA believes that approving this new 
method will provide laboratories with the flexibility to adopt the new 
technology if they have additional applications for it. The 
instrumentation is especially promising in the area of trace metal 
speciation. Laboratories that are performing that type of analysis 
would find it very useful to also be able

[[Page 49615]]

to perform bromate compliance monitoring analyses by EPA Method 321.8. 
EPA believes that advances in analytical technology should be 
encouraged when they provide additional options for obtaining accurate 
and precise data for compliance monitoring. Approval of this method 
would not require laboratories to adopt the new technology; it strictly 
offers the choice for laboratories that would like to use the latest 
technology.
    EPA is proposing to add sample collection and holding time 
requirement to EPA Method 321.8. The current method does not address 
the potential for changes in bromate concentrations after the sample is 
collected as a result of reactions with hypobromous acid/hypobromite 
ion. Hypobromous acid/hypobromite ion are intermediates formed as 
byproducts of the reaction of either ozone or hypochlorous acid/
hypochlorite ion with bromide ion. If not removed from the sample 
matrix, further reactions may form bromate ion. The reactions can be 
prevented by adding 50 mg of ethylenediamine (EDA)/L of sample. This is 
the preservation technique specified in the other methods both approved 
and proposed for bromate compliance analyses. The fortified drinking 
water samples analyzed in the second laboratory validation study of EPA 
Method 321.8 (Day et al. 2001) and the Information Collection Rule 
samples that were analyzed using the SAC method and EPA Method 321.8 
were preserved with EDA, thus demonstrating that EDA can be used in 
samples analyzed by IC/ICP-MS. EPA believes that adding this sample 
preservation requirement to EPA Method 321.8 will help ensure sample 
integrity. It will also simplify the sampling protocols that water 
systems must follow, because all sampling for bromate, regardless of 
the method employed to analyze the sample, will require the same sample 
preservation technique.
    EPA Method 321.8 does not include information concerning how long a 
sample may be stored prior to analysis. EPA is proposing to specify a 
maximum of 28 days for the sample holding time. This would make the 
method consistent with the other bromate methods proposed today and the 
method that is currently approved.
    g. EPA 415.3 for TOC and SUVA (DOC and UV254). Today's 
rule proposes to add EPA Method 415.3 (USEPA 2003r) as an approved 
method for TOC and SUVA. The Stage 1 DBPR included three Standard 
Methods for TOC and one method for UV254. Additional quality 
control (QC) requirements were included for these measurements, because 
the methods did not contain the necessary criteria. The rule included 
instructions for calculating SUVA based on UV254 and DOC 
analyses. The new EPA Method 415.3 includes the additional QC necessary 
to achieve reliable determinations for TOC, DOC, and UV254. 
It describes a procedure for removing inorganic carbon from the sample 
prior to the organic carbon analysis. The method uses the same 
technologies as already approved. The advantage of this new method is 
that it documents the precision and accuracy that can be expected when 
proper QC procedures are implemented and it places all the necessary 
information for SUVA in one place.
    EPA Method 415.3 provides sensitivity, precision and accuracy data 
for TOC and DOC measured using five different technologies:
    (1) Catalyzed 680[deg]C combustion oxidation of organic carbon to 
carbon dioxide (CO2) followed by nondispersive infrared 
detection (NDIR).
    (2) High temperature (700 to 1100[deg]C) combustion oxidation 
followed by NDIR.
    (3) Elevated temperature (95-100[deg]C) catalyzed persulfate 
digestion of organic carbon to CO2 followed by NDIR.
    (4) UV catalyzed persulfate digestion followed by NDIR.
    (5) UV catalyzed persulfate digestion followed by membrane 
permeation into a conductivity detector.

These technologies are included in the currently approved Standard 
Methods 5310 B and 5310 C (APHA, 1996). The new method indicates these 
technologies can provide detection limits between 0.02 mg/L and 0.12 
mg/L. Accuracy and precision data from analyses of fortified reagent 
water and natural waters indicate the technologies can produce 
acceptable data for determining compliance with the treatment technique 
for control of disinfection byproduct precursors specified in Sec.  
141.135. Seven natural waters were fortified with organic carbon from 
potassium hydrogen phthalate and analyzed by each of the five 
technologies. The average recoveries ranged from 97% to 103% for TOC 
and 98% to 106% for DOC.
    The method presents data from the analyses of seven different 
waters and demonstrates that comparable analytical results are obtained 
regardless of the technology used as long as all inorganic carbon is 
removed from the sample prior to the analysis. The samples ranged in 
concentration from 0.4 to 3.6 mg/L and the relative standard deviations 
across the analyses ranged from 35% RSD (for the lowest concentration 
sample) to <=13% RSD for the remainder of the samples.
    EPA Method 415.3 includes a procedure to ensure that inorganic 
carbon does not interfere with the organic carbon analyses. Since this 
is critical to obtaining accurate organic carbon determinations, EPA is 
proposing to add a requirement at Sec. Sec.  141.131(d)(3) and (4)(i) 
to remove inorganic carbon prior to performing TOC or DOC analyses. 
Laboratories will have the option of using the procedure described in 
EPA Method 415.3 or verifying that the process used by their TOC 
instrument adequately removes the inorganic carbon prior to the organic 
carbon measurement. Determination of organic carbon by subtracting the 
inorganic carbon from the total carbon is not acceptable for compliance 
purposes, because the percentage of inorganic carbon is usually large 
in relation to the organic carbon of the sample and the subtraction 
process introduces a large potential for error.
    The manufacturer of one of the instruments that was used during the 
development of EPA Method 415.3 recommends that hydrochloric acid be 
used to acidify TOC and DOC samples prior to analysis. EPA confirmed 
that use of this acid is critical for proper operation of the 
instrument. However, use of hydrochloric acid is in conflict with the 
current regulation at Sec. Sec.  141.131(d)(3) and (4)(i) which specify 
phosphoric or sulfuric acid. The type of acid used to preserve samples 
and to treat the samples to remove inorganic carbon prior to the 
organic carbon analysis should be based on the analytical method or the 
instrument manufacturer's specification. Therefore, EPA is proposing to 
remove the specification of acid type from Sec. Sec.  141.131(d)(3) and 
(4)(i).
    EPA Method 415.3 specifies that TOC samples be acid preserved at 
the time of collection in order to prevent microbial degradation of the 
organic carbon. This is consistent with the sampling instructions in 
the currently approved methods (Standard Methods 5310 B, 5310 C, and 
5310 D). EPA proposes to amend Sec.  141.131(d)(3) by removing the 
phrase ``not to exceed 24 hours'' in the description of when samples 
must be preserved, so that the rule is consistent with the method 
specifications.
    Analyses for both DOC and UV254 are required for a SUVA 
determination. The DOC measurement is identical to the TOC measurement 
after the sample is filtered through a 0.45 [mu]m pore size filter. The 
filtration step must be

[[Page 49616]]

performed using a prewashed filter in order to eliminate positive 
interferences from material that can leach from improperly cleaned 
filters. EPA Method 415.3 contains a description of how to properly 
rinse the filters and how to verify that the filter blank is 
acceptable. The method demonstrates that it is feasible to have a 
filter blank with a DOC concentration <0.2 mg/L. The method also 
provides performance data for DOC.
    The UV254 analysis that is part of the SUVA 
determination is also described in EPA Method 415.3. As with the DOC 
measurement, the UV254 analysis is performed on a sample 
that has been filtered through a prewashed 0.45 [mu]m pore size filter. 
In addition to verifying that the filter blank is low enough, the 
method also includes a spectrophotometer check procedure to ensure that 
the spectrophotometer is operating properly.
4. What Additional Regulated Contaminants Can Be Monitored by Extending 
Approval of EPA Method 300.1?
    In addition to bromate, chlorite, and bromide, EPA Method 300.1 
(USEPA 2000l) can also be used to determine chloride, fluoride, 
nitrate, nitrite, orthophosphate, and sulfate in drinking water. A 
comparison of the performance of EPA Method 300.1 to the currently 
approved EPA Method 300.0 (USEPA 1993) is shown in Table V-18 and 
demonstrates that EPA Method 300.1 provides comparable or better 
precision, accuracy, and sensitivity for these contaminants based on 
the single laboratory data presented in each method.

                             Table V-18.--Comparison of EPA Methods 300.0 and 300.1
----------------------------------------------------------------------------------------------------------------
           QC parameter               Chloride     Fluoride     Nitrate      Nitrite    Phosphate-P    Sulfate
----------------------------------------------------------------------------------------------------------------
                              Precision (Max % RSD in fortified water samples) \1\
----------------------------------------------------------------------------------------------------------------
EPA 300.0.........................          5.7           18          4.8          3.6          3.5          7.1
EPA 300.1.........................         0.22         0.85         0.41         0.77          4.7         0.39
-----------------------------------
                         Accuracy (Range of % Recoveries in fortified water samples) \2\
----------------------------------------------------------------------------------------------------------------
EPA 300.0.........................       86-114        73-95       93-104       92-121        95-99       95-112
EPA 300.1.........................        93-98        80-89        88-96        72-87        61-92           89
-----------------------------------
                                           Detection Limit (mg/L) \3\
----------------------------------------------------------------------------------------------------------------
EPA 300.0.........................         0.02         0.01        0.002        0.004        0.003         0.02
EPA 300.1.........................        0.004        0.009        0.008        0.001        0.019       0.019
----------------------------------------------------------------------------------------------------------------
\1\ The highest relative standard deviation (%RSD) reported in the method for replicate analyses of fortified
  water samples in a single laboratory.
\2\ The range of recoveries reported for replicate analyses of fortified water samples in a single laboratory as
  shown in the method.
\3\ The detection limit as determined by analyzing seven or more replicates of reagent water that is fortified
  with low concentrations of the anions. The standard deviation of the mean concentration for each analyte is
  calculated and multiplied by the student's t-value at 99% confidence and n-1 degrees of freedom (3.143 for 7
  replicates).

    EPA is proposing to extend approval of EPA Method 300.1 for 
fluoride, nitrate, nitrite, and orthophosphate (Sec.  141.23(k)(1)) and 
for chloride and sulfate (Sec.  143.4(b)) even though these 
contaminants are not addressed in today's proposed rule. As discussed 
before for dalapon, EPA believes that extending approval to all the 
regulated contaminants covered in a method provides greater flexibility 
to laboratories and allows them to reduce analytical costs. EPA 
recognizes that laboratories will probably not be determining 
concentrations of these non-DBP anions for compliance purposes in the 
same samples as used for chlorite or bromate compliance monitoring. 
However, EPA believes allowing the same method to be used even if the 
samples are not the same is more cost effective for laboratories. EPA 
is not proposing to withdraw any methods for the non-DBP anions, 
because that would place an unnecessary burden on laboratories that do 
not need to use EPA Method 300.1.
5. Which Methods in the 20th Edition and 2003 On-Line Version of 
Standard Methods Are Proposed for Approval?
    The Stage 1 DBPR approved eight methods (4500-Cl D, 4500-Cl F, 
4500-Cl G, 4500-Cl E, 4500-Cl I, 4500-Cl H, 4500-ClO2 D, and 
4500-ClO2 E) for determining disinfection residuals from the 
19th edition of Standard Methods (APHA, 1995). Standard Methods 6251 B 
and 4500-CIO2 E in the 19th edition of Standard Methods 
(APHA, 1995) were approved for HAA5 and daily chlorite analyses, 
respectively. Three TOC methods (5310 B, 5310 C, and 5310 D) from the 
Supplement to the 19th edition of Standard Methods (APHA, 1996) and one 
UV254 method (5910 B) from the 19th edition of Standard 
Methods (APHA, 1995) were also approved in the Stage 1 DBPR.
    These thirteen methods are unchanged in the 20th edition of 
Standard Methods (APHA, 1998), so EPA proposes to cite the 20th edition 
for these analyses in addition to the 19th editions.
    The On-Line Version of Standard Methods is an effort to provide the 
consensus methods to the public prior to the release of the next full 
publication. Standard Methods is making sections of the next version 
available for purchase in both electronic or printed format. EPA has 
reviewed the applicable sections and determined that ten of the methods 
are identical to the currently approved versions from the 19th 
editions. Section 4500-Cl contains the methods for determining chlorine 
residuals and it includes the 4500-Cl D, 4500-Cl F, 4500-Cl G, 4500-Cl 
E, 4500-Cl I, and 4500-Cl H. Section 4500-ClO2 contains the 
methods for determining chlorine dioxide residuals and chlorite and it 
includes method 4500-ClO2 E. Section 5310 contains the 
methods for determining TOC and it includes methods 5310 B, 5310 C, and 
5310 D. Because the ten listed methods in these sections are unchanged 
from the versions that were published in the 19th editions, EPA is 
proposing to cite the On-Line Version for these analyses in

[[Page 49617]]

addition to the currently approved 19th editions and the proposed 20th 
edition.
    Section 6251 includes method 6251 B for HAA5. The method has been 
updated for the On-Line Version to include precision and accuracy data 
from the Information Collection Rule and the sample holding time has 
been extended from 9 days to 14 days. The additional quality control 
data does not technically change the method from the previously 
approved version in the 19th edition; it simply demonstrates the 
performance that can be expected when the method is used. The change in 
sample holding time is consistent with EPA's proposal to standardize 
the HAA5 sample holding time at 14 days (See discussion in section 
V.O.7). Thus EPA is proposing to cite the On-Line Version for this 
analysis in addition to the currently approved 19th edition and the 
proposed 20th edition.
    Section 5910 includes method 5910 B for determining 
UV254. The method has been updated for the On-Line Version 
to include precision data from the Information Collection Rule. Because 
the additional quality control data does not technically change the 
method from the previously approved version in the 19th edition, EPA is 
proposing to cite the On-Line Version for this analysis in addition to 
the currently approved 19th edition and the proposed 20th edition.
    The On-Line Version of Standard Methods will not include method 
4500-ClO2 D, so it is not being proposed with the other 
twelve methods cited in the On-Line Version.
    EPA is proposing to add a citation to the 20th edition and the On-
Line Version of Standard Methods for thirteen and twelve methods, 
respectively. EPA believes these should be cited in addition to the 
19th editions in order to allow flexibility for the water systems 
performing the analyses. Withdrawal of the older editions would require 
all systems to purchase one of the newer editions, which could impose 
an unnecessary burden on systems that use the reference for only a few 
methods.
6. What Is the Updated Citation for EPA Method 300.1?
    EPA Method 300.1 (USEPA 2000l) for bromate, chlorite and bromide is 
now included in an EPA methods manual that was published August 2000. 
The manual titled ``Methods for the Determination of Organic and 
Inorganic Compounds in Drinking Water'' is a compilation of methods 
developed by EPA for drinking water analyses. EPA Method 300.1 was 
previously only available as an individual method. EPA proposes to 
update the bromate, chlorite, and bromide citation for this method to 
the August 2000 methods manual in today's rule so that the users are 
directed to the correct source of the method.
7. How Is the HAA5 Sample Holding Time Being Standardized?
    The analytical methods approved for HAA5 compliance monitoring (EPA 
552.1, EPA 552.2, and Standard Method 6251 B) all specify the use of 
ammonium chloride to eliminate the free chlorine residual in samples 
and they require samples be iced/refrigerated after collection. Even 
though the sampling parameters agree in the three methods, the methods 
specify different sample holding times (time between sample collection 
and extraction). EPA Methods 552.1 (USEPA 1992) and 552.2 (USEPA 1995) 
allow at least 14 days while Standard Method 6251 B (APHA 1995 and 
1998) specifies that samples must be extracted within nine days of 
sample collection. The holding time for the Standard Method is based on 
data which indicated an increase in DCAA concentration to slightly 
greater than 120% of the initial concentration after the sample was 
stored for 14 days (Krasner et al. 1989). All other HAA5 compounds were 
well within the 80-120% criteria set by the researchers. The decision 
was made to use a conservative approach to be sure that the 
concentrations of all HAAs were stable, and nine days was the closest 
data point to the 14 day-data point in question. Subsequent to 
Krasner's study, EPA conducted additional sample holding time studies 
as part of the EPA methods development process. EPA has published data 
to support the 14-day sample holding time for the HAA5 compounds 
(Pawlecki-Vonderheide et al. 1997; USEPA 2003p). Since there is no 
technical reason for the holding times to be different between the HAA5 
methods addressed in this rule, EPA proposes to allow a 14-day sample 
holding time for samples being analyzed by Standard Method 6251 B. This 
would provide consistency across methods and it would simplify sampling 
considerations for water systems. EPA is only proposing to standardize 
the holding time allowed for the samples. Due to differences in the 
sample preparation (i.e., extraction) procedures in the various 
methods, the extract holding times cannot be standardized. Laboratories 
must follow the individual method requirements when determining storage 
conditions and holding times for the extracts.
    EPA Method 552.1 specifies a 28-day holding time for HAA samples. 
This was based on studies conducted on fortified reagent water samples 
rather than drinking water samples. Because HAAs have been shown to 
biodegrade in some distribution systems (Williams et al. 1995), EPA 
believes that some samples may not be stable for 28 days. Today's rule 
proposes reducing the holding time to 14 days when EPA Method 552.1 is 
used in order to better ensure sample stability. During the Information 
Collection Rule, EPA only allowed the 14-day sample holding time for 
all HAA samples (regardless of the method used to analyze the samples), 
so laboratories and water systems have demonstrated their capability to 
implement this method change.
    EPA believes that by standardizing the sample holding times allowed 
in the various HAA5 methods, the burden for laboratories and water 
systems will be reduced. Sampling considerations will be simplified, 
because all HAA5 samples will be collected and stored the same way.
8. How Is EPA Clarifying Which Methods Are Approved for Magnesium 
Determinations?
    The Stage 1 DBPR allows systems practicing enhanced softening that 
cannot achieve the specified level of TOC removal, to meet instead one 
of several alternative performance criteria, including the removal of 
10 mg/L magnesium hardness (as CaCO3) from the source water. Analytical 
methods for measuring magnesium hardness were not included in the rule, 
but they were later promulgated in a Methods Update Rule (USEPA 1999b). 
The December 1999 Methods Rule cited the magnesium methods at Sec.  
141.23(k)(1), but it did not identify that these methods were to be 
used to demonstrate compliance with the alternative performance 
criteria specified in Sec.  141.135(a)(3)(ii). EPA is proposing to 
clarify this today by referencing the approved magnesium methods at 
Sec.  141.131(d)(6) and Sec.  141.135(a)(3)(ii).
9. Which Methods Can Be Used To Demonstrate Eligibility for Reduced 
Bromate Monitoring?
    Today's rule proposes to change the monitoring requirements for 
demonstrating eligibility to reduce bromate monitoring from monthly to 
quarterly. The Stage 1 DBPR allows the monitoring to be reduced if the 
system demonstrates that the average source water bromide concentration 
is less than 0.05 mg/L based upon monthly bromide measurements for one 
year. Today's rule proposes to change that requirement to a 
demonstration that the finished water

[[Page 49618]]

bromate concentration is <0.0025 mg/L as a running annual average. If 
this change is implemented, there will no longer be a need for bromide 
compliance monitoring methods. EPA is proposing additional bromide 
methods today in order to provide flexibility to the laboratories and 
water systems in the interim period before the Stage 2 DBPR compliance 
monitoring requirements becomes effective.
    In order to qualify for reduced bromate monitoring, EPA is 
proposing that the samples must be analyzed for bromate using either 
EPA Method 317.0 Revision 2.0 (UV/Vis detector), EPA Method 326.0 (UV/
Vis detector), or EPA Method 321.8. These three methods can provide 
quantitative data for bromate concentrations as low as 0.001 mg/L, thus 
ensuring that a bromate running annual average of <0.0025 mg/L can be 
reliably demonstrated. Laboratories that analyze samples by these three 
methods must report quantitative data for bromate concentrations as low 
as 0.001 mg/L.
    Since EPA Methods 317.0 Revision 2.0, 326.0, and 321.8 offer 
significantly greater sensitivity for bromate analyses, EPA considered 
whether these should be the only methods approved for bromate 
compliance monitoring. However, the new methods using postcolumn 
reactions with UV/Vis detection (EPA Methods 317.0 Revision 2.0 and 
326.0) or IC/ICP-MS (EPA Method 321.8) require greater analyst skill 
than is necessary for the standard ion chromatographic (IC) methodology 
(EPA Method 300.1 and ASTM Method D 6581-00). They also require 
instrumentation that may not be currently owned by many laboratories 
that perform bromate analyses. As a result of these factors and because 
the standard IC methods are adequate for determining compliance with 
the bromate MCL that was promulgated as part of the Stage 1 DBPR, EPA 
decided not to propose withdrawal of the currently approved method (EPA 
Method 300.1). In addition, EPA decided to propose ASTM Method D 6581-
00, because it is equivalent to EPA Method 300.1. EPA strongly 
encourages laboratories to expand their services by adding the 
capability to perform analyses using one of the more sensitive methods 
for bromate. EPA believes that there will be a shift to the more 
sensitive methods as water systems realize that the analytical 
capabilities are available for a slightly increased analytical cost. 
(The ability to determine bromate concentrations as low as 1 [mu]g/L 
will provide water systems more information concerning the optimization 
of ozone application to control for bromate formation.)
10. Request for Comments
    EPA requests comments on whether the methods proposed today should 
be approved for compliance monitoring.
    EPA solicits comments as to whether standardizing the sample 
holding times for the HAA5 methods is appropriate. Specifically, should 
the sample holding time for Standard Method 6251 B be extended from 9 
days to 14 days and should the sample holding time for EPA Method 552.1 
be shortened from 28 days to 14 days?
    EPA requests comments as to whether laboratories should be required 
to switch to one of the more sensitive bromate methods for compliance 
monitoring sample analyses. Should EPA Method 300.1 be withdrawn as a 
compliance monitoring method for bromate and be replaced by EPA Methods 
317.0 Revision 2.0, 326.0, and 321.8 which provide reliable data for 
bromate concentrations as low as 1[mu]g/L?

P. Laboratory Certification and Approval

1. What Is EPA Proposing Today?
    EPA recognizes that the effectiveness of today's proposed 
regulation depends on the ability of laboratories to reliably analyze 
the regulated disinfection byproducts at the proposed MCLs. EPA has 
established a drinking water laboratory certification program that 
States must adopt as part of primacy. Laboratories must be certified in 
order to analyze samples for compliance with the MCLs. EPA has also 
specified laboratory requirements for analyses, such as alkalinity, 
bromide, disinfectant residuals, magnesium, TOC, and SUVA, that must be 
conducted by parties approved by EPA or the State. EPA's ``Manual for 
the Certification of Laboratories Analyzing Drinking Water'' (USEPA 
1997b) specifies the criteria that EPA uses to implement the drinking 
water laboratory certification program. Today's proposed rule maintains 
the requirements of laboratory certification for laboratories 
performing analyses to demonstrate compliance with MCLs and all other 
analyses to be conducted by approved parties. It revises the acceptance 
criteria for performance evaluation (PE) studies and proposes reporting 
limits for the DBPs as part of the certification program. Today's rule 
also proposes that TTHM and HAA5 analyses that are performed for the 
IDSE or system-specific study be conducted by laboratories certified 
for those analyses.
2. What Changes Are Proposed for the PE Acceptance Criteria?
    The Stage 1 DBPR specified that in order to be certified the 
laboratory must pass an annual performance evaluation (PE) sample 
approved by EPA or the State using each method for which the laboratory 
wishes to maintain certification. The acceptance criteria for the DBP 
PE samples were set as statistical limits based on the performance of 
the laboratories in each study. This was done because EPA did not have 
enough data to specify fixed acceptance limits.
    Subsequent to the 1998 promulgation, EPA evaluated the results for 
the EPA Water Supply (WS) PE studies and the Information Collection 
Rule PE studies to determine if fixed acceptance limits could now be 
applied. (Fixed limits were used during the Information Collection 
Rule).
    Four different fixed limits (+/-20%, +/-30%, +/-40%, and +/-50% of 
the true value) were applied to each analyte in the WS PE study TTHM, 
HAA5, bromate, and chlorite samples. Successful analysis of the sample 
was defined as passing all four THMs individually in the TTHM PE 
sample; passing four of the five HAAs in the HAA5 PE sample; and 
passing bromate and chlorite individually. The number and percentage of 
laboratories that successfully passed each study sample were determined 
for the four fixed limits. These results were then evaluated to 
determine how narrow the criteria could be set in order to achieve 
accurate data and also provide enough certified laboratories to meet 
the capacity needs. Only the last six WS PE Studies administered by EPA 
(WS36-WS41 conducted between 1996-1998) were used in the final 
recommendation, because they provided a better estimate of current 
laboratory capabilities. Table V-19 summarizes the results of this WS 
PE Study evaluation.
    The number of laboratories that analyzed WS TTHM PE samples was 
significantly larger than for the other DBPs, because a laboratory 
certification program for TTHM has been in effect since the 
promulgation of the THM rule in 1979 (USEPA 1979). Most of the 
analytical methods for TTHM have been in use for many years, and the 
laboratories are experienced in their use. The Stage 1 DBPR established 
the first requirements to monitor for the other DBPs and certification 
was not required until December 2001. Therefore, the WS PE results for 
HAA5, chlorite, and bromate were from laboratories that were not part 
of a certification process and the laboratories

[[Page 49619]]

were using methods that were relatively new. In addition, the method 
used for bromate during the WS studies was EPA Method 300.0 which was 
replaced by EPA Method 300.1 in the Stage 1 DBPR, because Method 300.1 
is more sensitive. Laboratories would be expected to have greater 
success in passing the bromate PE samples using Method 300.1 and the 
bromate methods that are being proposed in today's rule.

                                               Table V-19.--Fixed Limit Evaluation of WS PE Studies 36--41
                                            [Average  and % of labs successfully completing studies]
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                        +/-20% of TV              +/-30% of TV              +/-40% of TV              +/-50% of TV
                   DBP Sample                    -------------------------------------------------------------------------------------------------------
                                                  Labs    %Labs    Labs    %Labs    Labs    %Labs    Labs    %Labs
--------------------------------------------------------------------------------------------------------------------------------------------------------
TTHM............................................          609           73          731           88          773           93          788           94
HAA5 \1\........................................           50           37           83           61          103           75          115           84
chlorite........................................           55           63           68           78           72           82           74           85
bromate.........................................           45           50           52           57           57           64           60          68
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Study 38 was excluded from this analysis, because a valid DCAA true value was not available for the HAA sample.

    Based on the results from the analyses described previously, EPA 
believes it is reasonable to set the TTHM acceptance criteria at +/-20% 
around the study true values. The number of laboratories capable of 
performing TTHM analyses is large and the results described previously 
show that in the time frame of 1996-1998, over 70% of the laboratories 
could successfully meet the +/-20% criteria. The PE studies conducted 
during the Information Collection Rule used the same acceptance 
criteria (USEPA 1996b).
    The data indicate that +/-40% are probably the tightest criteria 
that could be used to evaluate HAA5 PE samples. Setting this criteria 
balances the need for approval of enough labs to meet monitoring 
capacity and the need to provide data of acceptable accuracy. The +/-
40% criteria is consistent with the Information Collection Rule PE 
study acceptance criteria and it is tighter than the criteria 
established in the Stage 1 DBPR. During the Information Collection 
Rule, laboratories that were approved using the +/-40% criteria were 
able to provide accurate and precise data as evidenced by the quality 
control data collected when the Information Collection Rule samples 
were analyzed (Fair et al. 2002). Of the 1,250 Information Collection 
Rule samples that were fortified with known amounts of HAAs, the median 
recovery was 103% and the recoveries ranged between 89% and 120% in 80% 
of the fortified samples. There were 1,211 Information Collection Rule 
samples that were analyzed in duplicate and the median relative percent 
difference for those HAA5 analyses was 4%. Ninety percent of the 
analyses had RPDs less than 21%. EPA believes laboratories that are 
certified using the +/-40% criteria in PE studies should be capable of 
performing at a level comparable to the Information Collection Rule 
laboratories.
    EPA believes chlorite PE samples should be evaluated using a +/-30% 
criteria. Over 70% of the laboratories could meet this requirement for 
chlorite in the WS studies.
    The percentage of passing labs for bromate is almost 60% when a +/-
30% criteria is applied to the WS study data. Since the data do not 
accurately reflect the bromate methods that are now being used by 
laboratories, EPA believes a greater percentage of laboratories would 
pass the bromate PE study using today's technology. Unfortunately, EPA 
does not have the data to verify this assumption, because EPA no longer 
conducts PE studies. Even if the assumption is flawed, a 57% acceptance 
rate would still provide enough certified laboratories to handle the 
number of bromate samples required for compliance monitoring under the 
Stage 1 DBPR.
    The proposed acceptance criteria are listed in Table V-20.

                      Table V-20.--Proposed Performance Evaluation (PE) Acceptance Criteria
----------------------------------------------------------------------------------------------------------------
                                                   Acceptance
                       DBP                           limits                         Comments
                                                    (percent)
----------------------------------------------------------------------------------------------------------------
TTHM
    Chloroform                                          +/-20   Laboratory must meet all 4 individual THM
    Bromodichloromethane                                +/-20    acceptance limits in order to successfully pass
    Dibromochloromethane                                +/-20    a PE sample for THMs.
    Bromoform                                           +/-20
HAA5
    Monochloroacetic Acid                               +/-40   Laboratory must meet the acceptance limits for 4
    Dichloroacetic Acid                                 +/-40    out of 5 of the HAA5 compounds in order to
    Trichloroacetic Acid                                +/-40    successfully pass a PE sample for HAA5.
    Monobromoacetic Acid                                +/-40
    Dibromoacetic Acid                                  +/-40
Chlorite                                                +/-30
Bromate                                                 +/-30
----------------------------------------------------------------------------------------------------------------

    EPA is also proposing that the PE acceptance limits described 
previously become effective within 60 days of promulgation of the final 
rule. This will allow the laboratory certification program to implement 
the fixed limits as soon as possible. Laboratories that were certified 
under the Stage 1 PE acceptance criteria would be subject to the new 
criteria when it is time for them to analyze their annual DBP PE 
samples(s).

[[Page 49620]]

3. What minimum reporting limits are being proposed?
    The Consumer Confidence Reports Rule (USEPA 1998i) requires that 
all detected regulated contaminants be reported in the annual reports, 
but detection is not defined for the DBP contaminants. This rule 
addresses the deficiency by proposing reporting limits for the 
regulated DBPs.
    Laboratories that analyze compliance samples must be able to 
reliably measure the DBPs at concentrations below the MCL. Laboratories 
must also be able to measure the individual TTHM and HAA5 compounds at 
levels that are much lower than the MCLs for these compound classes, 
because the MCLs are based on the sum of the individual compound 
concentrations.
    Historically, EPA has used practical quantitation levels to 
estimate the lowest concentration at which laboratories can be expected 
to provide data within specified limits of precision and accuracy 
during routine operating conditions (USEPA 1985). The estimates are 
based on PE data, if available, or are set at five or ten times the 
method detection level.
    In today's rule, EPA is proposing an alternate approach for 
establishing the lowest concentration for which laboratories are 
expected to report quantitative data for DBPs. The approach is based on 
a unique data set from the Information Collection Rule. Laboratories 
were required to meet specific quality control criteria when they 
analyzed samples for the Information Collection Rule. The rule 
established a regulatory minimum reporting level (MRL) for each analyte 
and laboratories were required to demonstrate they could accurately 
measure at these concentrations each time a set of samples was 
analyzed. The regulatory MRLs were based on recommendations from 
experts who were experienced in DBP analyses and were set at 
concentrations for which most laboratories were expected to be able to 
meet the precision and accuracy criteria under normal operating 
conditions. Most samples were also expected to contain concentrations 
greater than the specified MRLs.
    EPA evaluated the data from the Information Collection Rule to 
determine if the laboratories were able to reliably measure down to the 
required MRL concentrations. Precision and accuracy data from the 
calibration check standards prepared at the MRL concentrations (listed 
in Table V-21) were examined. The data indicated most laboratories were 
able to provide quantitative data for samples with these 
concentrations.
    Because laboratories demonstrated the capability to meet the 
Information Collection Rule MRLs, EPA believes it is reasonable to 
expect similar performance during the analyses of DBP compliance 
monitoring samples. In today's rule, EPA is proposing to incorporate 
MRL requirements into the laboratory certification program for DBPs and 
to use regulatory MRLs as the minimum concentrations that must be 
reported as part of the Consumer Confidence Reports (Sec.  141.151(d)).

                        Table V-21.--Proposed Minimum Reporting Level (MRL) Requirements
----------------------------------------------------------------------------------------------------------------
                                                      MRL ([mu]g/L)
                                           ----------------------------------
                    DBP                       Information                                  Comments
                                               collection     Proposed stage
                                                  rule            2 DBPR
----------------------------------------------------------------------------------------------------------------
TTHM
    Chloroform............................              1.0              1.0
    Bromodichloromethane..................              1.0              1.0
    Dibromochloromethane..................              1.0              1.0
    Bromoform.............................              1.0              1.0
HAA5
    Monochloroacetic Acid.................              2.0              2.0
    Dichloroacetic Acid...................              1.0              1.0
    Trichloroacetic Acid..................              1.0              1.0
    Monobromoacetic Acid..................              1.0              1.0
    Dibromoacetic Acid....................              1.0              1.0
Chlorite..................................             20.0            200.0
Bromate...................................              5.0       5.0 or 1.0  Laboratories that use EPA Methods
                                                                               317.0 Revision 2.0, 326.0, or
                                                                               321.8 must meet a 1.0 [mu]g/L MRL
                                                                               for bromate.
----------------------------------------------------------------------------------------------------------------

    As part of the request for certification, EPA is proposing to 
require laboratories to demonstrate they can reliably measure 
concentrations at least as low as the ones listed in Table V-21 in 
order to be certified for those parameters. This would mean that the 
calibration curve must encompass the proposed regulatory MRL 
concentration and that the laboratory must verify the accuracy of the 
calibration curve at the lowest concentration for which quantitative 
data are reported by analyzing a calibration check standard at that 
concentration prior to analyzing each batch of samples. (Laboratories 
would analyze a check standard at the specified MRL concentration daily 
or each time samples are analyzed.) The measured concentration for this 
check standard must be within +/-50% of the expected value. 
Laboratories may choose to report quantitative data at concentrations 
lower than the proposed regulatory MRLs as long as the required 
accuracy criteria (+/-50% of the expected value) is met by daily 
analyzing standards at the lowest reporting limit chosen by the 
laboratory.
    Laboratories were not given the opportunity to report 
concentrations lower than the specified MRLs during the Information 
Collection Rule. Some laboratories indicated they have met the 
precision and accuracy criteria at lower concentrations, so EPA 
believes that each laboratory should have the flexibility to continue 
using its own reporting limits as long as the laboratory MRLs are not 
higher than the regulatory ones proposed in this rule. This flexibility 
would minimize the cost of implementing the regulatory MRL 
requirements, because the laboratory would not have to make changes in 
its established quality control procedures unless its procedures are 
less stringent than those being proposed today. Requiring a laboratory 
to adopt regulatory MRLs that are higher than the laboratory reporting 
limits currently in

[[Page 49621]]

use offers no advantage and could increase analytical costs. The 
capability to provide quantitative data at the laboratory's MRL or the 
regulatory MRL would need to be demonstrated on a daily basis by 
analyzing a check standard at that concentration and by achieving a 
recovery in the range of 50 to 150%.
    The proposed regulatory MRL for MCAA is 2.0 [mu]g/L based on the 
Information Collection Rule performance data. However, MCAA was not 
present at concentrations higher than this in more than half of the 
samples analyzed for HAAs during the Information Collection Rule (USEPA 
2003o). Some laboratories reported that they could have provided 
quantitative data for MCAA down to concentrations as low as 1.0 [mu]g/
L.
    EPA is proposing a regulatory MRL for chlorite that is much higher 
than can easily be achieved using the approved or proposed methods. The 
MRL specified during the Information Collection Rule was 20. [mu]g/L 
and laboratories were able to successfully obtain quantitative data at 
that level. However, in the context of this rule, EPA believes that 
requiring laboratories to verify their calibration curves down to 20. 
[mu]g/L each time samples are analyzed is unnecessary. This is because 
chlorite analyses are only performed on samples from water plants that 
use chlorine dioxide and most of the applied chlorine dioxide is 
converted to chlorite, so the concentrations that are expected in most 
compliance monitoring samples will be much higher than 20. [mu]g/L. 
(The Information Collection Rule data showed a median chlorite 
concentration of 380 [mu]g/L in the finished water and 333 [mu]g/L as 
the distribution system average in systems using chlorine dioxide 
(USEPA 2003o).) EPA is proposing a regulatory MRL of 200. [mu]g/L for 
chlorite, because most of the samples are expected to contain 
concentrations higher than 200. [mu]g/L. The MCL for chlorite is 1.0 
mg/L (1,000 [mu]g/L). EPA recognizes that setting the regulatory MRL 
for chlorite based on the concentrations expected to be found in the 
samples rather than the sensitivity of the analytical method is 
inconsistent with the approach taken for other compounds in this rule. 
Nevertheless, EPA believes setting the MRL based on occurrence 
information is appropriate because it will not compromise the 
compliance data. Water systems would have the option of requiring that 
laboratories establish a lower reporting limit when their samples are 
analyzed and EPA would encourage this in cases in which the samples 
consistently contain chlorite concentrations that are <200. [mu]g/L. If 
a lower reporting limit is used, then the laboratory will be required 
to meet the precision and accuracy requirements at that lower 
concentration by daily successfully analyzing a check standard at the 
laboratory reporting limit concentration prior to analyzing compliance 
samples. EPA believes very few water systems will request more 
sensitive chlorite analyses, because their samples won't have low 
enough concentrations to require it.
    EPA is proposing two regulatory MRLs for bromate analyses in 
today's rule. This is because the traditional ion chromatographic (IC) 
methods using conductivity detection (EPA Method 300.1 and ASTM Method 
6581-00) are only capable of quantitating down to 5.0 [mu]g/L while the 
new IC methods using either post column reactions with UV/Vis detection 
(EPA Methods 317.0 Revision 2.0 and 326.0) or IC followed by ICP-MS 
detection (EPA Method 321.8) can reliably quantitate bromate 
concentrations as low as 1.0 [mu]g/L. EPA believes it is appropriate to 
set the regulatory MRL based on the capability of the method. (EPA has 
published detection limits for inorganic contaminants based on method 
capability (Sec.  141.23(a)(4)(i)), so the approach proposed today is 
consistent with previous regulations.) If the regulatory MRL is based 
on the most sensitive method, then the routine IC methods could no 
longer be used even though they are adequate for demonstrating 
compliance with the bromate MCL. If the regulatory MRL is set using the 
least sensitive method, then the feasibility for reduced bromate 
monitoring based on a running annual average of <0.0025 [mu]g/L (<2.5 
[mu]g/L) would not be adequately demonstrated based on data reported 
with a reporting limit of 5.0 [mu]g/L.
    EPA is proposing MRLs as part of the certification process. 
Laboratories would be required to demonstrate they can reliably 
quantitate at the specified MRL concentration when their current DBP 
certification is subject to renewal or if they are applying for 
certification for DBP methods for the first time. (Demonstration would 
be accomplished by providing precision and accuracy data from the 
analyses of check standards at or below the regulatory MRL 
concentration over a several day period. The laboratory's standard 
operating procedure for HAA5 analyses would include a requirement to 
daily meet the MRL accuracy criteria for a check standard at or below 
the regulatory MRL concentration.) Although ensuring laboratories can 
meet the regulatory MRLs is a new certification requirement, EPA does 
not believe this significantly increases the time required to review a 
laboratory prior to certification. Each DBP method requires the 
laboratory to generate a similar set of data at a higher concentration 
and to meet specific accuracy and precision criteria as part of the 
initial demonstration of laboratory capability to perform the method; 
review of the MRL data set will be comparable to what is already being 
done. This new requirement will ensure that laboratories can reliably 
analyze samples that contain low concentrations of DBPs on an on-going 
basis.
    EPA is also proposing to require the regulatory MRLs be used for 
compliance reporting by the Public Water Systems. Finally, the 
regulatory MRLs would be used when Public Water Systems inform 
customers of their water quality relative to DBP concentrations in the 
annual Consumer Confidence Reports.
4. What Are the Requirements for Analyzing IDSE Samples?
    EPA is proposing that the TTHM and HAA5 samples collected for the 
Initial Distribution System Evaluations (IDSE) and the system specific 
studies conducted in lieu of IDSEs be analyzed by certified 
laboratories. EPA recognizes that this will require additional 
laboratory capacity during the time period in which these studies are 
conducted. The largest challenge will be in developing the capacity to 
analyze the samples for the water systems that must complete the 
studies, analyze the data, and recommend Stage 2 DBP sampling sites 
within two years of the promulgation date of the rule. However, EPA 
believes commercial laboratories, in particular, will be able to expand 
their capacity to meet the demand based in the information presented 
below.
    Assuming no waivers or system-specific studies, the number of IDSE 
samples is estimated to be between 14,000 and 21,000 per month in the 
first round of IDSE monitoring, depending on whether the monitoring 
requirements are based on population or number of treatment plants, 
respectively. Laboratories should easily be able to accommodate this 
increase in TTHM samples, because experience performing TTHM analyses 
is spread across a large number of laboratories. Hundreds of 
laboratories have been certified for TTHM analyses, since certification 
was first required in 1979. There were close to 600 laboratories 
certified to perform TTHM analyses in 1991. In the 1996-1998 period, 
there were over 800 laboratories participating in the PE studies for 
TTHMs and 600 of those laboratories were capable of meeting the

[[Page 49622]]

TTHM PE acceptance criteria proposed in today's rule. Many water system 
laboratories are certified to perform TTHM analyses and will be able to 
incorporate the IDSE TTHM samples from their systems into the 
laboratory schedule. It is reasonable to expect that commercial 
laboratories will be able to handle the remainder of the TTHM samples. 
(EPA does not have a current estimate of the number of laboratories 
certified to perform TTHM analyses. However, if the number of IDSE 
samples from large systems was evenly spread over the 600 laboratories 
that were certified in 1991, this would be less than 40 additional 
samples per month for each laboratory. Analysis of 40 TTHM samples 
would involve less than two days of analyst and instrument time which 
does not seem unreasonable for commercial laboratories to accommodate.)
    Analyses of the HAA5 samples will present a greater challenge, 
because certification is relatively new for this measurement. EPA 
anticipates that most of the HAA5 samples will be analyzed by 
commercial and State laboratories, because the methods are more complex 
than the TTHM analyses and monitoring was not widely required until 
January 2002. Laboratories were not required to be certified to perform 
HAA5 analyses until January 2002. However, the PE Study results from 
1996-1998 indicate that over 130 laboratories were performing HAA5 
analyses during that time frame and approximately 100 of those 
laboratories were capable of meeting the HAA5 PE acceptance criteria 
proposed in today's rule. Ninety-four laboratories were approved to 
perform HAA analyses during the Information Collection Rule; twenty-
seven of them were commercial laboratories and nine were State 
laboratories. EPA anticipates that large commercial laboratories 
already certified to perform HAA5 analyses will recognize this market 
potential and add staff and instrumentation to accommodate the 
increased demand.
    Most systems serving <10,000 people will not begin their IDSE 
studies until after the large systems have completed their studies. 
Even though the potential number of samples is greater, the small 
systems have two additional years in which to complete their studies, 
so there is more opportunity to schedule the sampling in such a manner 
that laboratory capacity is maintained. The laboratory capacity should 
be readily available by the time analyses of these samples are 
required.
5. Request for Comments
    EPA requests comments concerning the appropriateness of the 
proposed PE acceptance criteria.
    EPA solicits comments as to whether an MRL lower than 2 [mu]g/L is 
feasible for MCAA and if so, what should that MRL concentration be?
    EPA requests comments concerning whether the MRL for chlorite 
should be based on the sensitivity of the method (i.e., 20. [mu]g/L) or 
on the expected concentration range of the samples (i.e., 200. [mu]g/
L).
    EPA solicits comments concerning which MRL approach should be 
considered for bromate. Specifically, should EPA set the MRL based on 
the capability of the method which would mean that two different MRLs 
are defined or should one MRL be established based on either the least 
or most sensitive method?
    EPA requests comments concerning the appropriateness of the MRL 
certification requirements and whether additional certification 
requirements should be considered.
    EPA solicits comments on the availability of laboratory capacity to 
perform TTHM and HAA5 analyses for IDSE studies.

VI. State Implementation

    This section describes the regulations and other procedures and 
policies States would have to adopt to implement the Stage 2 DBPR, if 
finalized as proposed today. States must continue to meet all other 
conditions of primacy in 40 CFR part 142.
    The SDWA 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 SDWA 
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 SDWA, 
and (5) adopting and being capable of implementing an adequate plan for 
the provision of safe drinking water under emergency situations. 
General rule implementation activities include notifying systems of 
rule requirements, updating internal and external databases, providing 
training and technical assistance, and reviewing (and, if necessary, 
approving) monitoring and other reports and plans.
    To receive primacy for the Stage 2 DBPR, when final, States will be 
required to adopt the following new or revised requirements under their 
own regulations:

--Section 141.33(a) and (f), Record maintenance;
--Section 141.64, MCLs for disinfection byproducts;
--Subpart L, Disinfectant Residuals, Disinfection Byproducts, and 
Disinfection Byproduct Precursors;
--Subpart O, Consumer Confidence Reports;
--Subpart Q, Public Notification of Drinking Water Violations;
--Subpart U, Initial Distribution System Evaluation; and
--Subpart V, Stage 2B Disinfection Byproducts Requirements.

    In addition to adopting basic primacy requirements specified in 40 
CFR part 142, States are required to address applicable special primacy 
conditions. Special primacy conditions pertain to specific regulations 
where implementation of the rule involves activities beyond general 
primacy provisions. The purpose of these special primacy requirements 
in today's proposal is to ensure State flexibility in implementing a 
regulation that: (1) Applies to specific system configurations within 
the particular State and (2) can be integrated with a State's existing 
Public Water Supply Supervision Program. States must include these 
rule-distinct provisions in an application for approval or revision of 
their program. These primacy requirements for implementation 
flexibility are discussed in the following section.

A. State Primacy Requirements for Implementation Flexibility

    To ensure that a State program includes all the elements necessary 
for an effective and enforceable program within that State under 
today's rule, a State primacy application must include a description of 
how the State will review IDSE reports and approve new or revised 
monitoring sites for long-term DBP compliance monitoring. If a State 
will use the authority to grant blanket waivers for IDSE requirements 
to very small systems, it must comply with the special primacy 
provision for granting such waivers. A State that intends to use the 
authority for addressing consecutive system monitoring requirements 
must include a description of how it intends to implement that 
authority. A State primacy application must also include a description 
of how the State will require systems to identify significant 
excursions.

[[Page 49623]]

B. State Recordkeeping Requirements

    The current regulations in Sec.  142.14 require States with primacy 
to keep various records, including 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 Stage 2 DBPR 
requires that the State keep records related to any decisions made 
pursuant to the requirements in subparts U and V, plus copies of IDSE 
reports submitted by systems until those reports are reversed or 
revised in their entirety. Today's proposal also includes a revision to 
the State recordkeeping requirements that requires States to maintain 
records of DBP monitoring plans submitted by public water systems until 
superceded by a new system monitoring plan.

C. State Reporting Requirements

    EPA currently requires in Sec.  142.15 that States report 
information such as violations, variance and exemption status, and 
enforcement actions to EPA. The proposed Stage 2 DBPR will not add any 
additional reporting requirements.

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) (USEPA 1998j). The new process grants interim 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 complete 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 
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 
EPA, or the effective date of its revised regulations, whichever is 
later. In addition, a State which wishes to obtain interim primacy for 
future NPDWRs must obtain primacy for this rule.

E. IDSE Implementation

    As discussed in section V.J., many systems will be performing 
certain IDSE activities prior to their State receiving primacy. During 
that period, EPA will act as the primacy agency, but will consult and 
coordinate with individual States to the extent practicable and to the 
extent that States are willing and able to do so. In addition, prior to 
primacy, States may be asked to assist EPA in identifying and 
confirming systems that are required to comply with certain IDSE 
activities. Once the State has received primacy, it will become 
responsible for IDSE implementation activities.

F. State Burden

    Section VII of today's document contains an analysis of the burden 
that this rule will place on States in receiving primacy and 
implementing this rule.

G. Request for Comment

    EPA requests comment on the State implementation requirements 
including the special primacy requirements.

VII. Economic Analysis

    This section summarizes the Health Risk Reduction and Cost Analysis 
(HRRCA) in support of the Stage 2 DBPR as required by section 
1412(b)(3)(C) of the 1996 SDWA. In addition, under Executive Order 
12866, Regulatory Planning and Review, EPA must estimate the costs and 
benefits of the Stage 2 DBPR in an Economic Analysis (EA). EPA has 
prepared an EA to comply with the requirements of this order and the 
SDWA Health Risk Reduction and Cost Analysis (HRRCA) (USEPA 2003i). 
SDWA (Section 1412 (b)(4)(C)) also requires the Agency to determine 
that the benefits of the promulgated rule would justify the costs of 
compliance. The proposed EA is available in the docket and is also 
published on the Agency's web site: http://www.epa.gov/edocket.
    It is important to note that the regulatory options considered by 
the Agency are the direct result of an Advisory Committee process that 
involved various drinking water stakeholders. More information on this 
process is discussed in sections II and V of today's preamble.
    In order to analyze both benefits and costs of the proposed rule 
and other regulatory alternatives considered by the Agency, EPA relied 
on several data sources to understand DBP occurrence, an analytical 
model to predict treatment changes and changes in DBP occurrence, and 
input and analysis from expert technical review panels to assist with 
model validation and technology selection. A brief description of the 
process is outlined in section VII.E. but a more detailed explanation 
of the analytical process is in the EA for the proposed Stage 2 DBPR 
(USEPA 2003i).
    The Stage 2 DBPR economic impact analysis uses a model, (referred 
to as the Surface Water Analytical Tool or SWAT) and information 
collected under the Information Collection Rule to make predictions 
about finished water and delivered water DBP levels, as well as 
predicting technology changes necessary for systems to comply with rule 
alternatives. Specifically, SWAT estimates post-Stage 1 DBPR (pre-Stage 
2) and post-Stage 2 DBPR DBP levels and likely technology choices by 
the industry to achieve compliance. For smaller systems and for all 
ground water systems, expert panels considered occurrence data and 
current treatment technology specific to these systems and used this 
information to predict technology treatment changes that may result 
from this proposed rule.
    Both benefits and costs are presented as annualized 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. 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. 
The EA for the proposed rule (USEPA 2003i) also shows the undiscounted 
stream of both benefits and costs over the 25 year analysis period.

A. Regulatory Alternatives Considered by the Agency

    Today's proposed Stage 2 DBPR represents the second of a set of 
rules that address public health risks from DBPs. The Stage 1 DBPR was 
promulgated to decrease average exposure to DBPs and associated health 
risks by focusing compliance on MCLs based on average concentrations of 
TTHM and HAA5 within the distribution system. Today's proposed Stage 2 
DBPR further reduces exposure to chlorinated DBPs by basing compliance 
on the LRAA of TTHM and HAA5 concentrations at each sampling point 
within the distribution system. Section V illustrated the LRAA concept 
and differences in the two compliance calculation methodologies. In 
addition,

[[Page 49624]]

section V provided a comparison of the regulatory options considered. 
This subsection will summarize the comparison of options and subsection 
VII.B. will outline the exposure analyses that led EPA to propose the 
preferred option and will present the predicted national occurrence 
distributions that were used to quantify predicted exposure reductions 
from today's proposed rule. A detailed discussion of EPA's exposure 
analyses can be found in the Economic Analysis for the Stage 2 DBPR 
(USEPA 2003i).
    There are two components in the Agency's M-DBP regulatory 
development process that are particularly relevant to evaluation of 
options discussed in today's proposal: (1) the data synthesis and 
evaluation resulting from the Information Collection Rule; and (2) the 
analysis and recommendations of the M-DBP Advisory Committee. Data from 
the Information Collection Rule were used with the SWAT model to 
estimate the national distributions of DBP occurrence. The Advisory 
Committee considered several questions during the negotiation process, 
including:

--What are the remaining health risks after implementation of the Stage 
1 DBPR?
--What are approaches to addressing these risks?
--What are the risk tradeoffs that need to be considered in evaluating 
these approaches?
--How do the estimated costs of the approach compare to reductions in 
peak occurrences and overall exposure for that approach? How does this 
measure (ratio of costs to exposure reduction) compare among the 
approaches?

    The Advisory Committee considered the DBP occurrence estimates and 
characteristics of these distributions to be important in understanding 
the nature of public health risks. Although the Information Collection 
Rule data were collected prior to promulgation of the Stage 1 DBPR, the 
data support the concept that a system could be in compliance with the 
Stage 1 DBPR MCLs of 0.080 mg/L and 0.060 mg/L for TTHM and HAA5, 
respectively, and yet have points in the distribution system with 
either periodically or consistently higher DBP levels (see section IV).
    Based on these findings, and in order to address disproportionate 
risk within distribution systems, the Advisory Committee discussed an 
array of options that would base compliance on exposure at specific 
sampling locations rather than on average exposures for the entire 
distribution system. These included options for determining compliance 
as an LRAA (requiring systems to meet the MCL at individual sampling 
locations as a running annual average) or as absolute maximums 
(requiring that no samples taken exceed the MCL concentration), in 
addition to a combination of these approaches. For example, the 
Advisory Committee reviewed the exposure reductions for a number of 
approaches based on different LRAA and absolute maximum incremental MCL 
levels, and combinations of an LRAA approach with a companion absolute 
maximum for a variety of different concentration levels. The Advisory 
Committee also evaluated the associated technology changes and costs 
for these alternatives. In the process of narrowing down alternatives 
based on this vast amount of information, the Advisory Committee 
primarily focused on four types of alternative rule scenarios 
illustrated next.
Preferred Alternative
--Long-term MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as 
LRAAs.
--Bromate MCL remaining at 0.010 mg/L.
Alternative 1
--Long-term MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as 
LRAAs.
--Bromate MCL of 0.005 mg/L.
Alternative 2
--Long-term MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 as 
absolute maximums for individual measurements.
--Bromate MCL remaining at 0.010 mg/L.
Alternative 3
--Long-term MCLs of 0.040 mg/L for TTHM and 0.030 mg/L for HAA5 as an 
RAA.
--Bromate MCL remaining at 0.010 mg/L.

    Figure VII-1 shows how compliance would be determined under each of 
the TTHM/HAA5 alternatives described and the Stage 1 DBPR for a 
hypothetical large surface water system. This hypothetical system has 
one treatment plant and measures TTHM in the distribution system in 
four locations per quarter (the calculation methodology shown would be 
the same for HAA5). Ultimately, the Advisory Committee recommended the 
Preferred Alternative in combination with an IDSE requirement.
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    The Preferred Alternative, coupled with the IDSE's refocused 
sampling (see section V), was recommended by the Advisory Committee 
because this approach addresses the objective of reducing potential 
adverse reproductive and developmental health risks. It achieves this 
objective by controlling peak TTHM and HAA5 concentrations at sites 
throughout the distribution system without compromising microbial 
protection. At the same time, it will only require a few higher risk 
systems to face the cost of employing additional advanced technologies. 
While this alternative controls the occurrence of consistently high DBP 
levels, it is still possible that individual samples could exceed the 
MCL, and consumers could thus be exposed to higher DBP concentrations 
for some portion of the year. In addition, this alternative will 
further reduce average DBP levels as systems make changes to reduce 
these peak concentrations. Subsection VII.B. will show how today's 
proposed requirements are predicted to decrease exposure risks. The 
benefits and costs of each alternative are presented in subsections 
VII.C. through VII.E.

[[Page 49626]]

B. Rationale for the Proposed Rule Option

    DBP concentrations can be highly variable throughout a distribution 
system and over time at the same location in a distribution system 
(USEPA 2003o). The determination of compliance with an RAA under the 
Stage 1 DBPR requires a system to average all of their spatially-
distributed samples collected in one quarter of the year and to combine 
this average concentration with the three prior quarterly averages 
determined by the system. Thus, the RAA-based standard allows utilities 
to average spatial and temporal variability in TTHM and HAA5 samples to 
determine compliance, as shown in figure VII-1. This allows lower 
results found, perhaps, nearer a water treatment plant to offset higher 
results that might be found at the ends of the distribution system. In 
addition, systems with multiple plants of differing water quality 
(either multiple surface water plants or surface and ground water 
plants) may have particular plant distribution system sampling 
locations with high DBPs that are offset by lower measurements observed 
in the portion of the distribution network served by other plants.
    Under the Stage 2 DBPR proposed today, TTHM and HAA5 MCLs will 
remain the same, but compliance will be based on a locational running 
annual average (LRAA) for each of the sampling sites in the 
distribution system. In addition, the IDSE requirement will increase 
the probability that the compliance sampling sites will capture the 
highest DBP levels in the distribution system. Thus, the reduction in 
DBP exposure from the Stage 1 DBPR to the proposed Stage 2 DBPR results 
from the revised requirements for compliance calculations combined with 
new compliance monitoring sites.
    EPA expects the Stage 2 DBPR, as proposed, will result in health 
benefits by reducing the estimated health risks associated with the 
following exposures:

--Individual TTHM/HAA5 occurrences significantly exceeding 0.080 mg/L 
and 0.060 mg/L;
--Chronic exposures at individual distribution system locations that 
average more than 0.080 mg/L and 0.060 mg/L;
--Chronic exposures at all locations in the distribution system by 
reducing overall system average DBP concentrations; and
--Chronic and peak exposures in consecutive systems (systems that 
purchase treated water from another system).

    Under the Stage 1 DBPR, high DBP concentrations at specific 
locations in the distribution system could be masked by spatial and 
temporal averaging. As discussed in subsection VII.C, short term 
exposures resulting from these high concentrations may be of concern in 
regard to potential adverse reproductive and developmental health 
effects. Chronic exposures at locations having repeated high DBP 
concentrations may be of concern for cancer endpoints as well. The 
remainder of this subsection will illustrate how today's proposed rule 
is expected to reduce ``peak'' and average exposures to address these 
health concerns.
1. Reducing Peak Exposure
    EPA used Information Collection Rule data to estimate the reduction 
in exposure to DBP peaks resulting from the Stage 2 DBPR. Because the 
Information Collection Rule data represent pre-Stage 1 DBPR conditions, 
subsets of those plants already in compliance with the Stage 1 DBPR and 
Stage 2 DBPR were used to estimate pre-Stage 2 and post-Stage 2 
occurrence respectively. By comparing these subsets of data, EPA 
estimated that approximately 69% of plant locations having TTHM peaks 
greater than 0.080 mg/L remaining after the Stage 1 DBPR could be 
reduced through implementation of the Stage 2 DBPR. EPA conducted this 
additional peak reduction analysis only for TTHMs and not HAA5s because 
current epidemiological data only considers the association between 
TTHM exposure and adverse health impacts (see subsection VII.C). 
Additional information on reduction of peak exposures can be found in 
section 5.4.1 of the Economic Analysis (USEPA 2003i). EPA recognizes 
that temporal and spatial variability in systems that need to install 
treatment to comply with the Stage 1 DBPR may be different than in 
those that do not, perhaps due to low source water TOC concentrations. 
However, EPA does not have data representing DBP levels post-Stage 1. 
EPA requests comment on its approach of using data from plants in 
compliance with Stage 1 DBPR requirements without implementing 
additional treatment as a proxy for post-Stage 1 DBP levels.
2. Reducing Average Exposure
    To quantify the benefits of today's proposed rule, EPA compared 
predicted post-Stage 2 DBPR occurrence and compared this to the 
predicted baseline concentrations after the Stage 1 DBPR to determine 
reductions in exposure resulting from the Stage 2 DBPR. The SWAT model 
was the main tool used in this analysis. SWAT results were used 
directly for medium and large surface water systems. For small surface 
water systems and all ground water systems. Adjustments were made to 
the SWAT results to account for different percentages of plants 
changing technology to meet Stage 2 DBPR requirements. The Economic 
Analysis for today's proposed rule (USEPA 2003i) provides an in-depth 
discussion of this analysis.
    Table VII-2 shows the reduction in average plant-level TTHM and 
HAA5 concentrations estimated to result from the Stage 2 DBPR. EPA 
expects average DBP levels to decline by 4.7 percent for all surface 
water systems. DBP averages are expected to decline by 2.2 percent for 
all large ground water systems and 1.7 percent for all small ground 
water systems. These estimates include both systems already in 
compliance with the Stage 2 DBPR and systems making treatment changes 
to comply with the rule. The Agency uses these national average 
reductions to quantify the primary benefit of this rule which is the 
estimated range of reduction in bladder cancer cases nationally. 
Systems making treatment changes to comply with the rule will 
experience significantly greater estimated average reductions than the 
national average for all systems. Chapter 5 of the EA (USEPA 2003i) 
includes a more detailed discussion of this analysis.

                               Table VII-2.--Reduction in Average DBP Levels from Pre-Stage 2 to Post-Stage 2 (all plants)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                   Average plant-level TTHM               Average plant-level HAA5
                                                              System size          concentrations ([mu]g/L)               concentrations ([mu]g/L)
                       Source water                           (population  -----------------------------------------------------------------------------
                                                                served)                   Post-stage    Percent                  Post-stage    Percent
                                                                            Pre-stage 2       2        reduction   Pre-stage 2       2        reduction
--------------------------------------------------------------------------------------------------------------------------------------------------------
SW........................................................       <= 10,000         35.5         33.8          4.7         25.0         23.8          4.7

[[Page 49627]]

 
                                                                        35.5         33.8          4.7         25.0         23.8          4.7
                                                                    10,000
-----------------------------------------------------------
GW........................................................       <= 10,000         16.0         15.6          2.2          8.5          8.3          2.2
                                                                    10,000         16.2         16.0          1.7          8.6          8.5         1.7
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Due to rounding, percent reductions calculated from data in the tables may differ from the actual values presented here
Source: Economic Analysis (USEPA 2003i) Exhibit 5.22b

C. Benefits of the Proposed Stage 2 DBPR

    As described previously, the Stage 2 DBPR is expected to reduce 
both peak and long-term exposure to DBPs, thereby reducing the 
potential risk of both adverse reproductive and developmental health 
effects and bladder cancer. As discussed in section III of this 
preamble, both epidemiological and toxicological evidence suggest a 
possible increased risk for pregnant women and their fetuses who are 
exposed to DBPs in drinking water. The Agency believes and the Advisory 
Committee concluded that the weight of evidence is enough to take 
regulatory action to help address the potential reproductive and 
developmental endpoints in the Stage 2 DBPR. However, data are not 
available at this time to conduct a traditional quantitative risk 
assessment. Instead, the benefits from reducing most reproductive and 
developmental risks are discussed qualitatively in this preamble. For 
one endpoint, fetal loss, the Agency provides an illustrative 
calculation to explore the implications of some published results for 
potential benefits associated with reducing fetal losses that may be 
attributable to certain DBP exposures.
    In addition to achieving greater protection from possible adverse 
reproductive and developmental health effects, the rule may provide 
additional reduction in bladder cancer cases as the overall level of 
DBPs in distribution systems nation-wide decreases. The Agency 
estimated and monetized the potential benefits from reduction in 
bladder cancers resulting from this rule. Reductions in bladder cancer 
(including both fatal and non-fatal cases) provide a range of 
annualized present value benefits from $0 to $986 million using a three 
percent discount rate ($0 to $854 million using a seven percent 
discount rate) depending on the risk level assumed. These estimates are 
based on the assumption that the percent reductions in TTHM and HAAs 
will correspond to the percent reductions in bladder cancer risk 
attributed to populations receiving chlorinated drinking water as 
indicated by various epidemiology studies (USEPA 1998a). Zero is 
included in this range because of the inconsistent evidence regarding 
the association between exposure from DBPs and cancer.
    Other regulatory alternatives considered by the FACA committee and 
the Agency could provide greater benefits but with greater technology 
cost implications. Table VII-3 presents benefits estimates of the 
proposed Stage 2 DBPR using two population attributable risks derived 
from published studies (2% and 17%) and assuming there is a causal link 
between DBP exposure and bladder cancer. In subsection VII.G., Table 
VII-14 shows potential benefits of all regulatory alternatives 
considered by the Agency.
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    It is important to note that the monetized benefits only reflect 
estimated benefits from reductions in bladder cancer. As shown in 
subsection VII.C.1.and in Table VII-3, there may be significant 
nonquantifiable benefits associated with regulating DBPs in drinking 
water. Were EPA able to quantify some of the currently nonquantifiable 
health effects and other benefits potentially associated with DBP 
regulation, monetized benefits estimates could be significantly higher 
than what is shown in the table. A complete discussion of how EPA 
calculated the risks and the corresponding health benefits potentially 
associated with exposure to DBPs in drinking water can be found in the 
Stage 2 DBPR EA (USEPA 2003i).
    For additional perspective EPA used updated cancer risk factors for 
four DBPs for which we have toxicological data. Table III-3 (see 
section III of this preamble) shows the estimated pre-Stage 2 
concentrations of these four compounds and the estimated number

[[Page 49629]]

of people exposed to them. The Agency used these four DBPs to calculate 
an alternative baseline number of annual pre-Stage 2 cancer cases. The 
calculations use the linearized multistage model and predict 37 cases 
for the ED10 risk factors and 87 cases for the 
LED10 risk factors. The ED10 risk factors (also 
known as the maximum likelihood estimate) are based on the estimated 
dose that the model predicts will result in a carcinogenic response in 
10 percent of the subjects, while LED10 risk factors 
correspond to the lower 95% confidence bound on the dose that the model 
predicts will result in a carcinogenic response in 10% of the subjects 
(LED10 is EPA's more conservative and more commonly used 
expression of toxicologically based cancer risk). Assuming that DBP 
risk reductions for Stage 2 for the entire population average 4.2% 
(corresponding to the reduction in average TTHM levels), Stage 2 cancer 
cases avoided based on the toxicological data range from 1.7 to 4.0 
cases per year. Section 5.2.2.2 of the Economic Analysis (USEPA 2003i) 
presents a more detailed basis for the derivation of these estimates. 
It is important to note that these estimates do not include risks from 
dermal or inhalation exposure nor do they account for many other DBPs 
(or the mixture of DBPs seen in actual PWSs) for which occurrence or 
toxicological risk data do not exist.
1. Non-Quantifiable Health and Non-Health Related Benefits
    Although there are significant monetized benefits that may result 
from this rule from the reduction in bladder cancer, other important 
potential benefits of this rule are not quantified including potential 
reductions in adverse reproductive and developmental effects and other 
cancers.
    The primary purpose of the Stage 2 DBPR is to address potential 
adverse reproductive and developmental health effects that might be 
associated with DBP exposure. EPA concludes that, ``the epidemiologic 
data, although not conclusive, are suggestive of potential 
developmental, reproductive, or carcinogenic health effects in humans 
exposed to DBPs'' (Simmons et al 2002). EPA does not believe the 
available evidence provides an adequate basis for quantifying potential 
reproductive/developmental risks. Nevertheless, given the widespread 
nature of exposure to DBPs and the priority our society places on 
reproductive/developmental health, and the large number of fetal losses 
experienced each year in the U.S. (nearly 1 million (Ventura et al. 
2000)), we believe it is important to provide some quantitative 
indication of the potential risk suggested by some of the published 
results on reproductive/developmental endpoints, despite the absence of 
certainty regarding a causal link between disinfection byproducts and 
these risks. To do this, we have adapted illustrative PAR calculations 
from several studies on the relationship between chlorinated water 
exposure and fetal loss and applied these to national statistics on 
annual incidence of fetal loss.
    Specifically, we calculate the unadjusted population attributable 
risk associated with each of the three distinct population-based 
epidemiological studies of fetal loss published: Waller et al. 2001, 
King et al. 2000a, and Savitz et al. 1995. All three are high quality 
studies that have sufficient sample sizes and high response rates, 
adjust for known confounders \2\, and have exposure assessment 
information from water treatment data, residential histories, and THM 
measurements. Because the populations in these three studies appear to 
have TTHM exposures significantly greater than those of the general 
U.S. population, we have chosen to scale the results using Information 
Collection Rule data to allow us to derive population attributable 
risks that may be more relevant to the general U.S. population (USEPA 
2003i).
---------------------------------------------------------------------------

    \2\ Use of unadjusted PAR estimates has the effect of removing 
the adjustments for known confounders, however, EPA believes the 
unadjusted estimates are adequate for purposes of the illustrative 
calculations presented here.
---------------------------------------------------------------------------

    These three studies (using unadjusted data to allow for 
comparability, and scaled to the TTHM levels reported in the 
Information Collection Rule data base) yield median PARs of 0.4%, 1.7%, 
and 1.7% (with 95% confidence intervals for each of the studies of 0 to 
4%) \3\. Using the prevalence of fetal loss reported by CDC, the median 
PARs for these three studies suggest that the incidence of fetal loss 
attributable to exposure to chlorinated drinking water could range from 
3,900 to 16,700 annually. As part of the analysis to evaluate potential 
reduction in fetal loss for the Stage 2 DBPR, EPA assumed that 
reductions in risk are proportional to the 28 percent reductions in the 
number of locations having one or more quarterly TTHM measurements that 
exceed the study population cut-offs (75 to 81 
ug/l, depending on study). This analysis implies that a range of 1,100 
to 4,700 fetal losses could be avoided per year as a result of the 
Stage 2 rule.
---------------------------------------------------------------------------

    \3\ The negative lower 95% confidence intervals for all three 
studies was truncated at zero.
---------------------------------------------------------------------------

    Caution is required in interpreting the numbers because many 
experts recommend that population attributable risk analysis should not 
be conducted unless causality has been established. Causality has not 
been established between exposure to disinfection byproducts and fetal 
loss. The estimates presented here are not part of EPA's quantitative 
benefits analysis, and the ranges are not meant to suggest upper and 
lower bounds. Rather, they are intended to illustrate quantitatively 
the potential risk implications of some of the published results.
    EPA has not monetized the value of potential reductions in fetal 
loss, but recognizes that there is a significant value associated with 
improvements in reproductive and developmental health. In the absence 
of valuation studies specific to the health endpoints of concern, the 
Agency typically draws upon existing studies of similar health 
endpoints to estimate benefits. The ``transfer'' of the results of 
these studies to value similar health endpoints must be done carefully 
and methodically, controlling for differences in the health endpoints 
and in the relevant populations. Some researchers have attempted to 
transfer values using sophisticated analytical techniques such as 
preference calibration methods (e.g., Smith et al. 2002). Regardless of 
the approach used, ``benefit transfer'' requires systematic comparison 
of the differences in the health effects in the studies and those 
resulting from the regulation. Application of benefit transfer leads to 
a detailed qualitative examination of the implications of using those 
studies and potentially to empirical adjustments to the results of the 
existing studies.
    The Agency is investigating further work specific to the case of 
fetal loss valuation. One possible area of further research is the 
value that prospective parents attach to reducing risks during 
pregnancy. In this regard, the substantial lifestyle changes that 
prospective parents often undertake during pregnancy suggests that 
reducing these kinds of risks is of value. A second possible area of 
further investigation would be work on benefit transfer methodologies 
that address how existing studies can inform the estimation of the 
benefits of reduced fetal loss.
    EPA has not monetized the potential reductions in fetal loss. 
Without more information and discussion on these subjects the Agency 
cannot fully consider and describe the implications of relying upon 
existing studies.

[[Page 49630]]

However, research on valuation and benefit transfer continues to 
progress and the Agency anticipates new research and future efforts to 
value reproductive and developmental endpoints.
    EPA was also unable to quantify or monetize the benefit from 
potential reductions in other cancers, such as colon and rectal, that 
may result from this rule. Both toxicology and epidemiology studies 
indicate that other cancers may be associated with DBP exposure but 
currently there is not enough data to quantify or monetize these cancer 
risks.
    Other potential non-health related benefits not quantified or 
monetized in today's proposed rule include reduced uncertainty about 
becoming ill from consumption of DBPs in drinking water, the ability 
for some treatment technologies to eliminate or reduce multiple 
contaminants, and monitoring changes that will ensure that systems can 
effectively measure their DBP levels resulting in greater equity in 
protection from DBPs. First, the reduced uncertainty concept depends on 
several factors including consumer's degree of risk aversion, their 
perceptions about drinking water quality (degree to which they will be 
affected by the regulatory action), and the expected probability and 
severity of human health effects associated with DBPs in drinking 
water. This effect could be positive or negative depending on whether 
knowledge of the rule decreases or increases their concern about DBPs 
in drinking water and potentially associated health effects.
    Another nonquantified potential benefit is the impact of technology 
selection to address DBPs on a system's ability to address other 
contaminants. For example, membrane technology (depending on pore 
size), can be used to lower DBP formation but it can also remove other 
contaminants that EPA is in the process of regulating or considering 
regulating. Therefore, by installing membrane technology, a system may 
not have to make new capital improvement to comply with future 
regulations.
    Last, today's proposed rule makes changes to Stage 1 monitoring 
requirements. The IDSE monitoring provision of the proposed Stage 2 
DBPR will help systems identify locations to conduct their routine 
monitoring to capture high DBP occurrence levels. Also, the proposed 
Stage 2 DBPR will prevent a system from conducting sampling designed to 
avoid monitoring when DBP formation is generally higher. For example, 
the Stage 1 DBPR required systems to take quarterly samples but samples 
could conceivably be taken in December (4th quarter) and January (1st 
quarter) when the waters in the distribution system are colder and DBP 
formation generally lower. The proposed Stage 2 DBPR addresses this 
issue by requiring that the samples must be taken about 90 days apart. 
The benefits of these provisions include the greater certainty that 
health protection is actually achieved because it is more likely that a 
system's high DBP levels will be identified. In addition, the rule will 
reduce variability in the DBP levels throughout the distribution 
system, ensuring greater equity in public health protection.
2. Quantifiable Health Benefits
    Although DBPs in drinking water have been associated with non-
cancerous health effects discussed previously, the quantified benefits 
that result from today's rule are associated only with estimated 
reductions in DBP-related bladder cancer. A complete discussion of risk 
assessment methodology and assumptions can be found in Chapter 5 of the 
Stage 2 DBPR Economic Analysis (USEPA 2003i). Section III of this 
preamble also discusses the health effects that have been associated 
with DBP exposure.
    The annualized present value benefits for reductions in bladder 
cancer that are the result of today's rule for both community water 
system (CWS) and non-transient non-community water systems (NTNCWSs) 
range from $0 to $986 million using a three percent discount rate ($0 
to $854 million using a seven percent discount rate). Overall, the 
Stage 2 DBPR may reduce on average 0 to 182 bladder cancer cases per 
year.
    The lower estimate of zero is included because of inconsistent 
evidence regarding the association between exposure to DBPs and cancer. 
The upper estimate of monetized benefits and cases avoided is based on 
a population attributable risk (PAR) of 17 percent. Table VII-3 also 
presents monetized benefits based on a PAR value of 2%. The PAR 
estimates are derived from an analysis of five epidemiological studies 
which indicate that perhaps 2 to 17 percent of bladder cancers may be 
attributable to DBP exposure. These PAR estimates are described in more 
detail in section III of today's document. These are the same PAR 
values that EPA used in the Stage 1 DBPR benefits analysis, as 
discussed in the Regulatory Impact Analysis for the Stage 1 DBPR (USEPA 
1998f). Table VII-3 shows the estimated benefits associated with 
bladder cancer reduction as a result of the proposed rule. Table VII-4 
summarizes the mean, median and confidence intervals used to value 
reductions in bladder cancer.
    To calculate the total value of benefits derived from reductions in 
bladder cancer cases as a result of the Stage 2 DBPR, a stream of 
estimated monetary benefits is calculated by combining the annual cases 
avoided with valuation inputs using Monte Carlo simulation. Use of a 
Monte Carlo simulation allows the characterization of uncertainty 
around final modeling outputs based on the uncertainty underlying the 
various valuation inputs. The Stage 2 DBPR benefits model uses 
distributions of value of statistical life (VSL), willingness-to-pay 
(WTP), and income elasticity values to attribute monetary values (with 
uncertainty bounds) to the number of bladder cancer cases avoided.
    Several of the inputs needed in the benefit analysis, such as the 
VSL and WTP estimates, are based on older studies that were updated to 
current dollar values. In addition, both the VSL and WTP values are 
dependent on income levels. Therefore, these values also have to be 
adjusted for increases in real income growth from when the studies were 
conducted. The valuation inputs and an explanation of the update 
factors used to bring these values to current price levels and 
discussed in the following two sections.
    Valuation inputs. In order to monetize the benefit from the bladder 
cancer fatalities, EPA applied a VSL estimate to the cancer cases that 
result in mortality. EPA assumed a 26 percent mortality rate for 
bladder cancer (USEPA 1999d). The Agency uses a distribution of VSL 
values which are based on 26 wage-risk studies. The mean VSL value from 
these studies is $4.8 million in 1990 dollars. The mean value reflects 
the best estimate in the range of plausible values reflected by the 26 
studies. A more detailed discussion of these studies and the VSL 
estimate can be found in EPA's Guidelines for Preparing Economic 
Analyses (USEPA 2000b).
    The VSL represents the value of reducing the risk of a premature 
death. This valuation, however, does not take into account the medical 
costs associated with the period of illness (morbidity increment) 
leading up to a death. In its review of the Arsenic Rule, the Science 
Advisory Board (SAB) suggested that the appropriate measure to use in 
valuing the avoidance of the morbidity increment is the medical cost 
attributable to a cancer case (USEPA 2001e). Based on available medical 
data, EPA estimates the medical costs for a fatal bladder cancer case 
to be $93,927 at a 1996 price level (USEPA 1999d). This medical cost 
value (updated to 2000 price levels) is applied as a point

[[Page 49631]]

estimate to each fatal case of bladder cancer in the benefits model.
    A review of the available literature did not reveal any studies 
that specifically measured the WTP to avoid risks of contracting 
nonfatal cases of bladder cancer. Instead, two alternates were used, 
the WTP to avoid the risk of contracting a case of curable lymph cancer 
(lymphoma) and the WTP to avoid a case of chronic bronchitis. The SAB 
suggested this approach in their review of the Arsenic Rule (USEPA 
2001e). The median risk-risk trade-off for a curable case of lymphoma 
was equivalent to 58.3 percent of the risk attributed to reducing the 
chances of facing a sudden death and are derived from the Magat et al. 
study (1996). Therefore, the Agency applies the 58.3 percent to the VSL 
distribution to derive a range of value for non-fatal cancers with a 
mean WTP value of $2.8 million ($4.8 million * 58.3 percent) at a 1990 
price level. The WTP for avoiding a case of chronic bronchitis is based 
on the same methodology used for the Stage 1 DBPR (see Stage 2 DBPR EA 
(USEPA 2003i) for a complete discussion). The estimate is based on a 
lognormal distribution that uses the risk-dollar tradeoff estimate and 
has a mean of $587,500, standard deviation of $264,826, and a maximum 
value of $1.5 million at 1998 price values.
    Update factors. All valuation parameters must be updated to the 
same price level so comparisons can be made in real terms. Values for 
VSL, WTP, and the morbidity increment used in the model are updated 
based on adjustment factors derived from Bureau of Labor Statistics 
(BLS) consumer price index (CPI) data so that each represents a year 
2000 price level. Table VII-4 summarizes these updates.
[GRAPHIC] [TIFF OMITTED] TP18AU03.011

    Although the price level (year 2000) is held constant throughout 
the benefits model, projections of benefits in future years are subject 
to income elasticity adjustments. Income elasticity adjustments 
represent changes in valuation in relation to changes in real income. 
For fatal cancers, the Agency used a triangular distribution with a 
central estimate of 0.40 (low end: 0.08; high end:1.00) to represent 
the uncertainty of the income elasticity value. For non-fatal cancers, 
the Agency uses a triangular distribution with a central estimate of 
0.45 (low end: 0.25; high end: 0.60). These distributions are used as 
assumptions in the Monte Carlo simulation to further characterize 
uncertainty in benefits estimates.
    In order to apply the income elasticity values in the model, they 
are combined with projections of real income growth over the time frame 
for analysis. Population and real gross domestic product (GDP) 
projections are combined to calculate per-capita real GDP values. A 
more detailed discussion of these adjustments is in Chapter 5 of the EA 
(USEPA 2003i).
    The development of cancer due to exposure to environmental 
carcinogens involves a complex set of processes that are not well-
understood for most specific substances. In general, however, the 
development of cancer involves some time period, usually referred to as 
the latency period, between the initial exposure and the manifestation 
of disease. Defining a latency period is highly uncertain because the 
mode of action for most chemical contaminants are poorly understood. 
Latency periods in humans often involve many years, even decades.
    EPA recognizes that despite uncertainties in the latency period 
associated with different types of carcinogens, it is unlikely that all 
cancer reduction benefits would be realized immediately upon exposure 
reduction. If it is assumed that lower risk is attained immediately 
upon reduction in exposure, this would tend to overestimate the 
benefits. On the other hand, assuming that no risk reduction occurs for 
some period of time following exposure reduction may lead to an 
underestimation of the benefits. There will likely be some transition 
period as individual risks become more reflective of the new lower 
exposures than the past higher exposures.
    Recently, the Arsenic Rule Benefits Review Panel of the EPA Science 
Advisory Board (SAB) addressed this issue in detail and provided some 
guidance for computing benefits to account for this transition period 
between higher and lower steady-state risks (USEPA 2003s). The Arsenic 
Rule Benefits Review Panel coined the term ``cessation-lag'' to 
emphasize the focus on the timing of the attenuation of risk after 
reduction in exposures to avoid confusion with the more traditional 
term of ``latency'' that reflects the increased risk \4\ from the time 
of initial exposure.
---------------------------------------------------------------------------

    \4\ SAB included the following in its report on arsenic to 
emphasize this difference: ``An important point is that the time to 
benefits from reducing arsenic in drinking water may not equal the 
estimated time since first exposure to an adverse effect. A good 
example is cigarette smoking: the latency between initiation of 
exposure and an increase in lung cancer risk is approximately 20 
years. However, after cessation of exposure, risk for lung cancer 
begins to decline rather quickly. A benefits analysis of smoking 
cessation programs based on the observed latency would greatly 
underestimate the actual benefits.''

---------------------------------------------------------------------------

[[Page 49632]]

    Although the focus of the cessation lag discussion in the SAB 
review was on reducing levels of arsenic in drinking water, much of 
their consideration of this issue has more general applications beyond 
just the arsenic issue at hand. In particular, SAB noted the following:
    [sbull] The same model should be used to estimate the time pattern 
of exposure and response as is used to estimate the potency of the 
carcinogen.
    [sbull] If possible, information about the mechanism by which 
cancer occurs should be used in estimating the cessation lag (noting 
that late-stage mechanisms in cancer formation imply a shorter 
cessation lag than early stage mechanisms).
    [sbull] If specific data are not available for characterizing the 
cessation lag, an upper bound for benefits can be provided based on the 
assumption of immediately attaining steady-state results.
    [sbull] In the absence of specific cessation lag data, other models 
should be considered to examine the influence of the lag.
    Following the release of the SAB report on arsenic, EPA initiated 
an effort to explore approaches to including the cessation lag in 
modeling risk reduction and calculating benefits for the arsenic 
regulation. EPA recognized, however, that the concept of cessation lag 
is not only applicable to arsenic but to other drinking water 
contaminants having a cancer end-point as well.
    In response to the SAB cessation lag recommendations, EPA has:
    [sbull] Conducted a study using data on lung cancer risk reductions 
following cessation of smoking that resulted in the January 2003 report 
Arsenic in Drinking Water: Cessation Lag Model (USEPA 2003s).
    [sbull] Conducted an expert scientific peer review of that draft 
report.
    [sbull] Initiated development of general criteria for incorporating 
cessation lag modeling in benefits analyses for other drinking water 
regulations.
    In the effort to develop a cessation lag model specific to DBPs, 
EPA reviewed the available epidemiological literature for information 
relating to the timing of exposure and response, but could not identify 
any studies that were adequate, alone or in combination, to support a 
specific cessation lag model for DBPs in drinking water. Thus, in 
keeping with the SAB recommendation to consider other models in the 
absence of specific cessation lag information, EPA explored the use of 
information on other carcinogens that could be used as a indicator to 
characterize the influence of cessation lag in calculating benefits. 
The carcinogen for which the most extensive database was available for 
characterizing cessation lag was for cigarette smoking. EPA examined 
several extensive epidemiological studies on the comparison of the 
risks of adverse health effects, including lung cancer, for smokers and 
former smokers. EPA selected the Hrubek and McLaughlin (1997) study as 
the most appropriate study for development of a statistical model of 
disease response to smoking cessation. This was a comprehensive study 
involving a 26-year follow-up of almost 300,000 U.S. male military 
veterans. More detail about this study and how it is applied to 
estimate the cessation lag can be found in Chapter 5 of the EA (USEPA 
2003i) and the cessation lag document (USEPA 2003s).
    The smoking cessation lag data imply that the majority of the 
potential steady state cases avoided occur within the first several 
years, but with diminishing incremental increases in later years. For 
example, the cessation lag model indicates that approximately 40 
percent of the steady-state cases avoided are achieved by the end of 
the second year, with 70 percent achieved by the end of the fifth year, 
and approximately 80 percent by the tenth year. By the twentieth year, 
90 percent of the steady state cases are avoided.
    EPA recognizes that there are several factors that contribute to 
the uncertainty in the application of the specific cessation lag model 
used in the estimation of the benefits of the proposed Stage 2 
regulation. A key factor to consider in assessing this impact is the 
likely mode of action of DBPs in eliciting bladder cancer versus the 
mode of action of tobacco smoke in producing lung cancer, and in 
particular whether they behave as initiators or promoters of the 
carcinogenic process. As discussed in the SAB report and the EPA 
Cessation Lag report (USEPA 2001e, USEPA 2003s), carcinogens that act 
solely or primarily as initiators would tend to show a longer cessation 
lag (lower rate of risk reduction following reductions in exposure) 
than carcinogens that act solely or primarily as promoters. The 
available information on tobacco smoke and lung cancer suggests that it 
involves a mixture of both initiators and promoters, and therefore the 
cessation lag derived from smoking data is expected to reflect the 
combined influence of these divergent mechanisms. There are no data 
available on the mechanism of action for DBPs and bladder cancer; 
indeed the specific carcinogenic agent(s) present in disinfected water 
responsible for the observed effect have not been identified. The use 
of the tobacco smoke cessation lag model reflecting a mixture of 
initiators and promoters would be expected to attenuate a possible bias 
in either direction if the DBPs responsible for bladder cancer are 
acting predominately as either initiators or promoters.
    Another factor to consider is that the cessation lag model used is 
based upon exposure to tobacco smoke where lung cancer is the end-point 
but is being applied to exposure to disinfection by-products where the 
end-point is bladder cancer. Of concern here is that there is a more 
direct correlation between inhalation and the site of cancer for 
smoking than there is for ingestion and inhalation of drinking water 
and the sites of cancer for DBP exposure. Unfortunately, EPA does not 
have data on which to develop a cessation lag model using data specific 
to how changes in DBP exposures affect the risks of developing bladder 
cancer.
    Another divergence, and perhaps the most important, between the 
smoking model and the DBP application is that the smoking model is 
based on complete cessation of exposure, whereas in the case of DBP 
exposure is only being reduced. In some water systems the reduction is 
only 10 percent, whereas in others it may be as high as 60 percent, 
with an average of approximately 30%. This moderate reduction in 
exposure may prevent full DNA repair, which some scientists interpret 
as the basis for the short cessation lag associated with smoking.
    Currently, smoking is the only contaminant for which enough data 
exist to estimate a cessation lag. In the absence of a reliable 
cessation lag model based specifically on DBPs and bladder cancer, EPA 
used the cessation lag model based on smoking to provide a means of 
estimating the rate at which bladder cancer risk in the exposed 
population falls from the pre-Stage 2 levels to the post-Stage 2 
levels. However, this model is derived from data involving notable 
differences from DBPs in drinking water, including different cancer 
sites (lung versus bladder), different exposure pathways (inhalation 
versus a combination of ingestion, inhalation and dermal), different 
risk levels, and, perhaps most importantly, complete cessation for 
smoking versus small exposure decreases for DBPs. For these reasons, 
the extent to which the smoking / lung cancer model is directly 
transferable to DBP / bladder cancer is uncertain. It is not possible 
to know, however, whether and to what degree the tobacco smoke

[[Page 49633]]

cessation lag model either over-states or under-states the rate at 
which population risk reduction for bladder cancer occurs following DBP 
exposure reductions.
    EPA is currently examining the recently published meta-analysis by 
Villanueva et al. (2003) to determine if the information provided on 
increases in risk as a function of duration of exposure can provide any 
insight on how reductions in risk over time might occur following 
reductions in exposure. Villanueva et al. (2003) demonstrated that the 
risk associated with chlorinated drinking water and bladder cancer are 
related to exposure duration. Specifically, they estimated a unit 
increase in the odds ratio of 1.006 per year (95% CI of 1.004 to 
1.009). The model suggests a cumulative odds ratio of 1.13 after 20 
years of exposure (95% CI of 1.08 to 1.20), and 1.27 (95% CI of 1.17 to 
1.43) after 40 years. This result is consistent with most of the 
individual studies which do not show statistically significant risk 
increases until at least 30-40 years of exposure. However, these 
studies provide indirect evidence only about the latency of potential 
effects. For perspective, it is important to note that the latency 
between initiation of exposure and an increase in lung cancer risk is 
approximately 20 years. As noted above, latency is not the same as the 
cessation lag. EPA is requesting comment on (a) the potential 
application of the Villanueva et al. (2003) model to estimate 
reductions in bladder cancer risk that might accompany decreased 
exposure to DBPs as a result of the Stage 2 Rule; (b) the advantages 
and disadvantages of using the current approach--i.e., application of 
the smoking cessation lag model; and (c) suggestions for alternative 
data sets or approaches to characterize cessation lag.
    In addition to the delay in reaching a new steady-state level of 
risk reduction as a result of cessation lag effects, there is a delay 
in exposure reduction resulting from the Stage 2 DBPR implementation. 
In general, EPA assumes that a fairly uniform increment of systems will 
complete installation of new treatment technologies each year, with the 
last systems installing treatment by 2013. EPA recognizes that more 
systems may start in early or later years, but believes that a uniform 
schedule is a reasonable assumption. Appendix D of the EA presents 
detailed information regarding the rule activity schedule assumptions 
(USEPA 2003i).
    The delay in exposure reduction resulting from the rule 
implementation schedule is incorporated into the benefits model by 
adjusting the cessation lag weighting factor. For example, if ten 
percent of systems install treatment equipment (and start realizing 
reductions in cancer cases) in year one, only that portion of the cases 
are modeled to begin the cessation lag equilibrium process in that 
year. Thus, the resulting ``weighted weighting factor'' is higher 
relative to the base factor. Appendix E in the EA (USEPA 2003i) 
presents detailed breakdowns of all weighting factor adjustments and 
resulting cancer cases avoided, by year, for each rule alternative 
based on the application of the cessation lag methodology.
3. Benefit Sensitivity Analyses
    The Agency performed one other benefit sensitivity analysis which 
is included in the EA to allow for comparison with the benefit 
estimates calculated for the Stage 1 DBPR. This analysis assumes that 
there is not a cessation lag or latency adjustment associated with 
bladder cancer reductions that result from the rule. In this case, the 
analysis assumes that the steady state reduction in bladder cancer 
occurs immediately with rule implementation. This is the same 
methodology used to estimate the quantified benefits of the Stage 1 
DBPR.

D. Costs of the Proposed Stage 2 DBPR

    In estimating the costs of today's proposed rule, the Agency 
considered impacts on water systems (CWSs and NTNCWSs) and on States 
(including territories and EPA implementation in non-primacy States). 
EPA assumed that systems would be in compliance with the Stage 1 DBPR, 
which has a compliance date of January 2004 for ground water systems 
and small surface water systems and January 2002 for large surface 
water systems. Therefore, the cost estimate only considers the 
additional requirements that are a direct result of the Stage 2 DBPR. 
More detailed information on cost estimates are described later and a 
complete discussion can be found in Chapter 6 of the Stage 2 DBPR EA 
(USEPA 2003i)
1. National cost estimates
    EPA estimates that the mean annualized cost of the proposed rule 
ranges from approximately $59.1 million using a three percent discount 
rate to $64.6 million using a seven percent discount rate. Drinking 
water utilities will incur approximately 98 percent of the rule's 
costs. States will incur the remaining rule cost. Tables VII-5 a and b 
summarize the total annualized cost estimates for the proposed Stage 2 
DBPR. In addition to mean estimates of costs, the Agency calculated 90 
percent confidence bounds by considering the uncertainty around the 
mean unit technology costs. Table VII-6 shows the undiscounted capital 
cost and all one-time costs broken out by rule component. A table 
comparing total annualized costs among the regulatory alternatives 
considered by the Agency is located in subsection VII.G.
BILLING CODE 6560-50-P

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[GRAPHIC] [TIFF OMITTED] TP18AU03.014


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[GRAPHIC] [TIFF OMITTED] TP18AU03.013


[[Page 49637]]


2. Water system costs
    The proposed Stage 2 DBPR applies to all community or nontransient 
noncommunity water systems that add a chemical disinfectant other than 
UV or distribute water that has been treated with a disinfectant other 
than UV. EPA has estimated the cost impacts for both types of public 
water systems. As shown in Tables VII-5 a and b, the total annualized 
present value costs for CWSs is approximately $55.8 million and for 
NTNCWSs, $2.2 million, using a three percent discount rate ($60.8 
million and $2.2 million using a seven percent discount rate).
    Although the number of systems adding treatment is small, treatment 
costs make up a significant portion of the total costs of the rule 
(more than 75 percent of total rule costs). Table VII-7 shows the 
baseline number of plants and the estimated percent of those plants 
adding treatment. The estimated percent of plants adding advanced 
treatment or converting to chloramines is 2.8 percent of all systems. A 
higher percentage of surface water plants are predicted to add 
treatment compared to ground water plants. However, the baseline number 
of ground water plants is larger than that of surface water plants, so 
there is a larger number of ground water plants adding treatment. 
Subsection VII.F. provides a more detailed explanation of treatment 
changes that may occur as a result of the proposed rule.
    All systems will incur costs for rule implementation. Some will 
need to conduct a one-time Initial Distribution System Evaluation 
(IDSE) and others (a different subgroup depending on the system size) 
may incur additional costs for routine DBP monitoring. Some systems may 
also have to conduct a peak excursion evaluation if single samples 
indicate high DBP levels.
    Sixty-nine percent of surface water and 7 percent of ground water 
CWSs are predicted to conduct the IDSE monitoring. EPA estimates that a 
very small portion of systems (approximately 16 percent overall) will 
conduct additional routine monitoring beyond the Stage 1 DBPR 
requirements. However, fewer samples overall would be required if a 
population-based approach is implemented instead of the plant-based 
approach that is currently being used to estimate monitoring costs. 
Section V describes the population-based approach in more detail and a 
discussion of how this approach may influence costs is provided in 
Appendix H of the EA (USEPA 2003i). A small percentage of systems 
(approximately 3.0 percent of surface water CWSs and 0 percent of 
ground water systems) are expected to experience significant 
excursions.
    A complete discussion of the rule provisions is located in section 
V of this preamble; the Stage 2 DBPR Economic Analysis includes a 
complete analysis of rule impacts (USEPA 2003i). Table VII-8 summarizes 
the number of systems subject to non-treatment related rule activities. 
Column D indicates the number of systems expected to use the standard 
monitoring program to implement the IDSE. Column F indicates the number 
of systems expected to increase monitoring sites beyond that required 
by Stage 1. The last two columns show the number and percent of plants 
estimated to experience significant excursions each year.

[[Page 49638]]

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[[Page 49639]]


[GRAPHIC] [TIFF OMITTED] TP18AU03.016


[[Page 49640]]


    In addition to using distributions to develop unit cost estimates, 
the Agency conducted sensitivity analyses to further explore 
uncertainty regarding system compliance estimates. The first two 
sensitivity analyses were prepared to evaluate the possibility that the 
IDSE monitoring requirement will result in more systems needing to 
install treatment beyond what is predicted in the current cost model 
(see chapter 7 of the EA, USEPA 2003i, for details of this analysis). 
Table VII-9 lists the high-end estimates of the number of systems 
adding treatment in IDSE sensitivity analyses No. 1 and No. 2. For both 
IDSE sensitivity analyses, only small additional impacts were assumed 
possible for systems serving 10,000 people or fewer because such 
systems generally have much less complicated distribution systems than 
larger systems. EPA estimated that the mean annualized costs at the 3% 
discount rate could be as high as $77.5 million (IDSE Sensitivity 
Analysis No. 1) or $108.8 million (IDSE Sensitivity Analysis No. 2) 
versus the Preferred Alternative analysis estimate of $57.4 million. At 
the 7% discount rate these estimates would respectively correspond to 
$86.1 million, $120.7 million, and $63.3 million.
[GRAPHIC] [TIFF OMITTED] TP18AU03.017

    EPA believes that the percentage of systems estimated to add 
treatment under IDSE sensitivity analyses No. 1 and No. 2 are 
overestimates and that the estimate for the Preferred Alternative is 
likely to already capture the influence of the IDSE because of the 
conservative assumptions used in the analysis. For example, the 
compliance forecast analysis assumes that systems will try to meet the 
LRAA MCLs with a 20% margin of safety. Systems complying by switching 
to chloramines may choose to meet the new MCLs with a much smaller 
margin of safety since chloramines dampen the variability of DBP 
concentrations within the distribution system. Furthermore, EPA 
believes that the number of ground water and small surface water 
systems adding chloramines or changing technology in the baseline 
analysis may be overestimated because their monitoring requirements are 
expected to be very similar from Stage 1 to Stage 2. The Stage 1 DBPR 
required only one compliance monitoring location (at the point of 
maximum residence time) for producing surface water systems serving 
between 500 and 10,000 people and for all ground water systems. The 
Stage 2 DBPR requires that these systems add an additional site if they 
determine that their high TTHM and high HAA5 concentrations do not 
occur at the same location. If systems maintain a single monitoring 
location for the Stage 2 DBPR, as many are expected to do, calculation 
of compliance will produce the same results for the running annual 
average (RAA) and locational running annual average (LRAA) measure, 
implying that they are not likely to add treatment for the Stage 2 DBPR 
if they comply with the Stage 1 DBPR.
    EPA conducted a third sensitivity analysis to evaluate the 
possibility that small systems will continue to monitor at one point in 
their distribution system. In this sensitivity analysis, EPA assumed 
that no surface water plants serving fewer than 10,000 people and no 
ground water plants would add treatment to meet Stage 2 DBPR 
requirements (i.e., only costs are associated for large surface water 
systems). Under this analysis, the average cost figures are reduced 
dramatically from $57.4 million or $63.3 million to $22.9 million or 
$25.7 million using a 3 percent or 7 percent discount rate, 
respectively, for the Preferred Regulatory Alternative. Chapter 7 of 
the Economic Analysis (USEPA 2003i) contains a detailed explanation of 
the aforementioned sensitivity analysis.
3. State Costs
    The Agency estimates that the States and primacy agencies will 
incur an annualized present value cost of $1.1 million to $1.5 million 
(using a three percent and seven percent discount rate, respectively). 
In order to estimate the cost impact to States, EPA considered initial 
implementation costs, costs for assisting systems in evaluating IDSE 
information, and for annual rule implementation activities. EPA 
considered the incremental change in activities that result from the 
Stage 2 DBPR. For example, States may have to update their databases to 
track the new Stage 2 DBPR monitoring strategy but could modify the 
system they developed for the Stage 1 DBPR. EPA accounted for the cost 
of a Stage 1 DBPR database in the Stage 1 Regulatory Impact Analysis 
(USEPA 1998f). State costs are not expected to change dramatically 
between alternatives.
4. Non-quantifiable
    EPA has identified and quantified costs that it believes are likely 
to be significant. In some instances, EPA did not include a potential 
cost element because it believes the effects are relatively minor and 
difficult to estimate. For example, the Stage 2 DBPR may be the 
determining factor in the decision by some small water systems to merge 
with neighboring systems. Such changes have both costs (legal fees and 
connecting infrastructure) and benefits (economies of scale). Likewise, 
costs for procuring a new source of water would have costs for new 
infrastructure but could result in lower treatment costs.
    Also, EPA was unable to quantify several distribution system-
related

[[Page 49641]]

changes that can reduce TTHM and HAA5 levels. Activities such as 
looping distribution systems and optimizing storage can minimize 
retention times and help to control DBP formation. Costs for these 
activities range from almost zero (modifying retention time) to more 
substantial costs for modifying distribution systems. In the absence of 
detailed information needed to make cost evaluations for situations 
such as these, EPA has included a discussion of possible effects where 
appropriate.

E. Expected System Treatment Changes

    In order to quantify the effects of the Stage 2 DBPR, it is 
necessary to predict how plants will modify their treatment processes 
to meet the proposed requirements. To estimate the incremental impacts 
of the Stage 2 DBPR, relative to the Stage 1 DBPR, EPA compared 
predicted ``ending technologies'' (types of treatment in use after 
implementation of the Stage 2 DBPR) to the distribution of baseline 
technologies predicted to be in place after the implementation of the 
Stage 1 DBPR. This subsection outlines the process for deriving 
baseline and ending Stage 2 technology distributions that are the basis 
for the national cost estimates of today's proposed rule.
1. Pre-Stage 2 DBPR Baseline Conditions
    Development of the Pre-Stage 2 baseline (i.e., conditions following 
the Stage 1 DBPR) consists of the following processes:
    [sbull] Compiling an industry profile--identifying and collecting 
information on the segment(s) of the water supply industry subject to 
the Stage 2 DBPR;
    [sbull] Characterizing influent water quality--summarizing the 
relevant characteristics of the raw water treated by the industry; and
    [sbull] Characterizing treatment for the Stage 1 DBPR--predicting 
what the industry will do to comply with the provisions of the Stage 1 
DBPR.
    Section IV of this document details the data sources EPA used to 
characterize water quality and treatment practices for the nation's 
public water systems. EPA also used information in the Water Industry 
Baseline Handbook (USEPA 2000j) to develop the industry profile. The 
Baseline Handbook uses data derived from the 1995 Community Water 
Systems Survey and the Safe Drinking Water Information System to 
characterize the U.S. drinking water systems. Another EPA study, 
Geometries and Characteristics of Water Systems Report (USEPA 2000k), 
also provided information for the industry profile.
    EPA developed and used a model (SWAT) to characterize treatment 
following the Stage 1 DBPR and Stage 2 DBPR options considered. SWAT 
served as the primary tool to predict changes in treatment and DBP 
occurrence. The model used a series of algorithms and decision rules to 
predict the type of treatment a large surface water plant will use 
given a specific regulatory alternative and source water quality. Other 
tools were used to estimate practices at large ground water systems or 
any medium or small systems. A Delphi process (a detailed technical 
treatment characterization and DBP occurrence review by drinking water 
experts) was used to predict treatment changes for large ground water 
systems (those serving 10,000 or more people). The results of the SWAT 
analyses and the Delphi process were extrapolated to the medium surface 
water and ground water systems based on analysis of source water 
treatment characteristics and treatment decision trees. For the small 
surface and ground water systems analyses, a group of experts provided 
predictions for a pre-Stage 2 baseline and resulting treatment and 
water quality conditions under the Stage 2 DBPR regulatory 
alternatives. A detailed description of these analyses can be found in 
the Economic Analysis for the Stage 2 DBPR (USEPA 2003i).
2. Predicted Technology Distributions Post-Stage 2 DBPR
    The treatment compliance forecast for the Stage 2 DBPR has two 
components--1) the percent of plants that must add treatment to comply 
with Stage 2 DBPR requirements, and 2) the treatment technologies these 
plants are predicted to select. This information, coupled with the 
baseline data discussed before, provides an estimate of the total 
number of plants using specific technologies to meet the requirements 
of the proposed Stage 2 DBPR. National costs are then generated using 
technology unit cost information.
    The four step process EPA used to develop a Stage 2 DBPR compliance 
forecast is summarized in table VII-10. The difference between the 
Stage 1 DBPR Technology Selections and Stage 2 DBPR Technology 
Selections (Step 4--Incremental Technology Selections) was used to 
develop national cost estimates for today's proposed rule. Tables VII-
11 a and b (surface water) and VII-12 a and b (ground water) show the 
incremental technology selections shown as the percent change between 
Stage 1 and Stage 2 DBP rules.

         Table VII-10.--Stage 2 DBPR Compliance Forecast Summary
------------------------------------------------------------------------
              Step                          Description of Step
------------------------------------------------------------------------
1...............................  Model a pre-Stage 1 baseline scenario
                                   using Information Collection Rule
                                   data to allow consistent comparison
                                   between different rule alternatives.
2...............................  Model technology selection to meet
                                   Stage 1 DBPR requirements (Stage 1
                                   DBPR Technology Selection).
3...............................  Model technology selection to meet
                                   Stage 2 DBPR requirements (Stage 2
                                   DBPR Technology Selection).
4...............................  Subtract the results in Step 2 from
                                   Step 3 and adjust to obtain the
                                   incremental impact of an alternative
                                   (Stage 2 DBPR incremental technology
                                   selection).
------------------------------------------------------------------------


[[Page 49642]]

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[[Page 49643]]

[GRAPHIC] [TIFF OMITTED] TP18AU03.019

F. Estimated Household Costs of the Proposed Rule

    This analysis considers the potential increase in a household's 
water bill if a system passed the entire cost increase resulting from 
this rule on to their customers. It is a tool to gauge potential 
impacts and should not be construed as precise estimates of potential 
changes to individual water bills.
    Overall, the potential increase in mean annual water bill per 
household is estimated to be $8.38 for those systems that need to 
install technology to comply with this rule. Table VII-13 shows the 
range of household costs for all surface and ground water systems 
subject to the rule and also only for those systems installing 
technology to comply with this rule. For all systems, including those 
that may not have to take any additional action to comply with this 
rule but are still subject to its provisions, the mean annual household 
cost is $0.51. The last two columns of Table VII-13 show the potential 
impact as the percent of households that will incur either less than a 
$1 or less than a $10 increase in their monthly water bills (shown in 
the table as annual values). For systems adding treatment, 84% of 
households will face less than a $1 increase in their monthly bill, 
while 99% are expected to face less than a $10 increase.

[[Page 49644]]

[GRAPHIC] [TIFF OMITTED] TP18AU03.020

    Both household cost estimates reflect costs for rule implementation 
(e.g., reading and understanding the rule), IDSE, additional routine 
monitoring, and treatment changes. Although implementation and the IDSE 
represent relatively small, one-time costs, they have been annualized 
and included in the analysis to provide a complete picture of household 
costs.
    Overall, EPA estimates that 99 percent of the 98 million households 
that are provided disinfected drinking water would face less than $1 
increase in their monthly water bill. Approximately 86 percent of the 
households impacted by 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. Households served by small 
systems that install advanced technologies will face the greatest 
increases in annual costs. The cumulative distributions of household 
costs for all systems are presented in the Economic Analysis (USEPA 
2003i).
    When interpreting the results of the household cost analysis, it is 
important to remember that systems, especially small systems, may have 
other options that were not included in the compliance forecast. For 
example, the system may identify another water source that may form 
lower levels of TTHM and HAA5. Systems that can identify such an 
alternate water source may not have to treat that water as much as 
their current source, resulting in lower treatment costs that may 
offset the costs of obtaining water from the alternate source. Systems 
may also be able to connect to a neighboring water system. While 
connecting to another system may not be feasible for some remote 
systems, EPA estimates that more than 22 percent of all small water 
systems are located within metropolitan regions (USEPA 2000c) where 
distances between potential connecting water systems may not present a 
prohibitive barrier. Consolidation was not an element used in 
developing the compliance forecasts for small systems. Costs for 
consolidation may be either greater or less than the costs for changing 
technologies, and consolidation may have other benefits (e.g., lower 
costs for compliance with future regulations). In addition, potentially 
lower cost alternatives such as controlling water residence time in the 
distribution systems were not included in the compliance forecast.
    Also, more small systems than projected in the primary analysis may 
already be in compliance with Stage 2 DBPR. A sensitivity analysis 
discussed in the subsection VII.D.2 describes this issue in more 
detail. Also, certain technologies installed to treat DBPs may treat 
many other contaminants thus eliminating the need to install additional 
equipment to comply with future drinking water regulations.

G. Incremental Costs and Benefits of the Proposed Stage 2 DBPR

    Incremental costs and benefits are those that are incurred or 
realized in reducing DBP exposures from one alternative to the next 
more stringent alternative. Estimates of incremental costs and benefits 
are useful in considering the economic efficiency of different 
regulatory options considered by the Agency. However, as pointed out by 
the Environmental Economics Advisory Committee of the Science Advisory 
Board, efficiency is not the only appropriate criterion for social 
decision making (USEPA 2000n).
    Generally, the goal of an incremental analysis is to identify the 
regulatory option where net social benefits are maximized. If net 
incremental benefits

[[Page 49645]]

are positive, society is incurring greater costs as a result of the 
health damages compared to the costs society could pay to reduce those 
health damages (i.e. society would be better off to invest more in 
controlling the health damage). If net incremental benefits are 
negative, than the cost of the additional control is higher than the 
value of the additional health damages avoided. Therefore, the 
``efficient'' regulatory level is where the next additional incremental 
reduction in health damages equals the incremental cost of achieving 
that reduction. However, the usefulness of this analysis is constrained 
when major benefits and/or costs are unquantified or not monetized.
    For the proposed Stage 2 DBPR, presentation of incremental 
quantitative benefit and cost comparisons may be unrepresentative of 
the true net benefits of the rule because a significant portion of the 
rule's potential benefits are non-quantifiable (see section C.1). 
Tables VII-14 and VII-15 show the total estimated costs and benefits 
for each alternative. Evaluation of the incremental changes between 
different rows in the tables shows that incremental costs generally 
fall within the range of incremental benefits for each more stringent 
alternative. Equally important, the addition of any benefits 
attributable to the non-quantified categories would add to the benefits 
without any increase in costs.

                                         Table VII-14.--Total Annualized Present Value Costs by Rule Alternative
                                                                   ($millions, 2000$)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                         Total annualized cost ($millions)
                                                         -----------------------------------------------------------------------------------------------
                                                                      3 Percent discount rate                         7 Percent discount rate
                                                         -----------------------------------------------------------------------------------------------
                    Rule alternative                                        90 Percent confidence bound                     90 Percent confidence bound
                                                                         --------------------------------                -------------------------------
                                                           Mean estimate   Lower (5th %    Upper (95th %   Mean estimate   Lower (5th %    Upper (95th %
                                                                               tile)           tile)                           tile)           tile)
--------------------------------------------------------------------------------------------------------------------------------------------------------
Preferred...............................................           $59.1           $54.3           $63.9           $64.6           $59.2           $70.0
Alt. 1..................................................           182.2           165.1           199.6           195.1           175.9           214.3
Alt. 2..................................................           409.6           383.6           435.7           442.7           413.4           472.2
Alt. 3..................................................           594.3           556.3           631.9           644.2           601.1          686.9
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: Costs represent values in millions of 2000 dollars. Estimates are discounted to 2003--90 percent Confidence Intervals reflect uncertainty in
  technology unit cost estimates
Source: Economic Analysis (USEPA 2003i) exhibit 6.24


[[Page 49646]]

[GRAPHIC] [TIFF OMITTED] TP18AU03.029

    The range of quantified benefits increases significantly with 
Alternatives 2 and 3. However, the associated costs also increase 
significantly--cost figures presented in Table VII-14 show values 
approaching or exceeding $500 million

[[Page 49647]]

per year. Although the estimated benefits for Alternatives 2 and 3 are 
potentially significant, EPA rejected these alternatives because the 
Agency believes that the uncertainty about the health effects data does 
not warrant the additional expense associated with these regulatory 
alternatives.
    Given the uncertainty in the health effects, and the resulting 
rejection of Alternatives 2 and 3, a comparison of Alternative 1 with 
the Preferred Alternative shows that Alternative 1 would have 
approximately the same benefits as the Preferred Alternative but with 
greater costs. This results from the inability of the Agency to 
estimate the additional benefits of reducing the bromate MCL. 
Alternative 1 was also determined to be unacceptable due to the 
potential for increased risk of microbial exposure. See section VII.A 
of today's action for a description of regulatory alternatives.

H. Benefits From the Reduction of Co-Occurring Contaminants

    Installing certain technologies to control DBPs also has the added 
benefit of controlling other drinking water contaminants. For example, 
some membrane technologies (depending on pore size) installed to reduce 
DBP precursors can also reduce or eliminate many other drinking water 
contaminants, including arsenic and microbial pathogens. EPA has 
finalized a rule to further control arsenic level in drinking water and 
has proposed the Ground Water Rule to address microbial contamination. 
The Stage 2 DBPR is also being concurrently proposed with the Long Term 
2 Enhanced Surface Water Treatment Rule. 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.

I. Are There Increased Risks From Other Contaminants?

    Today's proposed rule may slightly shift the distribution of TTHM 
and HAAs to brominated species. Some systems, depending on bromide and 
organic precursor levels in the source water and technology selection, 
may experience a shift to higher ratios or concentrations of brominated 
DBPs while the overall TTHM or HAA5 concentration decreases. However, 
EPA anticipates that this phenomenon may only occur in a small 
percentage of systems affected. For most systems, overall levels of 
DBPs, as well as brominated DBP species, should decrease as a result of 
this rule.
    EPA's analysis shows that a large portion of systems that do not 
currently meet Stage 2 requirements will do so by switching from 
chlorination to chloramination; approximately 5% of surface water 
plants and 1.3% of ground water plants in systems serving greater than 
10,000 are estimated to convert to chloramination in order to comply 
with the Stage 2 DBPR from the Stage 1 DBPR (USEPA 2003i). A potential 
chloramination byproduct is N-nitrosodimethylamine (NDMA), a probable 
human carcinogen. The concern over the formation of NDMA in the 
treatment process is based on the compound's ability to persist for a 
long period of time in the distribution system. The mechanism of 
formation of NDMA, however, is still under examination. A number of 
ongoing studies will also evaluate occurrence, factors that affect NDMA 
formation, mechanisms, treatment effectiveness and improved analytical 
methods for measuring NDMA.
    Another contaminant of concern to the Agency is chlorite. Levels 
may increase slightly because of technology shifts to chlorine dioxide 
resulting from this rule but very few systems (<0.1 percent) are 
predicted to install this technology. However, individual systems will 
not shift to chlorine dioxide unless they can meet the chlorite MCL 
(established under the Stage 1 DBPR) which is considered protective of 
public health.
    EPA also considered the impact this rule may have on microbial 
contamination that may result from altering disinfection practices. To 
address this concern, the Agency developed this rule jointly with the 
Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR). EPA 
expects that the LT2ESWTR provisions will prevent significant increases 
in microbial risk resulting from the Stage 2 DBPR. EPA also expects the 
Ground Water Rule, scheduled for promulgation in 2003, to prevent any 
increases in microbial risk in ground water systems deemed vulnerable 
to source water contamination.

J. Effects on General Population and Subpopulation Groups

    Section III of today's proposed rule discusses the health effects 
associated with DBPs on the general population as well as the effects 
on pregnant women and fetuses. In addition, health effects associated 
with children and pregnant women are discussed in greater detail in 
subsection VIII.G of this preamble.

K. Uncertainties in Baseline, Risk, Benefit, and Cost Estimates

    Today's proposal models the current baseline risk from DBP exposure 
as well as the reduction in risk and the cost for various rule options. 
There is uncertainty regarding many aspects of this analysis including 
the risk calculation, the benefit estimate, and the cost estimates. EPA 
has tried to capture much of the uncertainty and also the variability 
associated with many of the inputs used in the economic analysis by 
using distributions or ranges as model inputs instead of point 
estimates whenever possible. The Stage 2 DBPR EA contains a more 
extensive discussion of the modeling techniques used to address 
uncertainty and variability (USEPA 2003i).
    In addition, the Agency conducted sensitivity analyses to address 
uncertainty. The sensitivity analyses focus on various benefit and cost 
factors that may have a significant influence on the outcome of the 
rule. All of these sensitivity analyses are explained in more detail in 
the EA for the Stage 2 DBPR (USEPA 2003i).
    The major source of benefit uncertainty is the scientific 
uncertainty regarding the impact of DBP exposure on reproductive and 
developmental outcomes. However, the Agency believes that the monetized 
value of these outcomes could be significant. As discussed in 
subsection VII.C.1, EPA performed an illustrative calculation that 
explored the potential implications for the proposed rule using some of 
the published results on fetal loss, but did not attempt to quantify 
benefits associated with reducing other reproductive and developmental 
endpoints potentially associated with DBP exposure.
    Another possible underestimation of today's monetized benefits 
results from the inability of the Agency to quantify or monetize the 
potential benefit from avoiding other cancers associated with DBP 
exposure such as colon and rectal cancers. Furthermore, while the 
Agency estimated the range of bladder cancer risks avoided to be 0 to 
182 cases per year, the true risk of bladder cancer avoided from 
decreased DBP exposure may be higher than this range.
    While EPA believes it has accounted for the significant costs of 
today's proposed rule, there are uncertainties about some of the cost 
inputs. As discussed in subsection VII.D.4, cost estimates do not 
include some alternatives to installing treatment (e.g., improving 
management of distribution system residence time) that may be a less 
costly means of complying with the

[[Page 49648]]

Stage 2 DBPR. The Agency also explored two additional uncertainties 
which might have the greatest impact on our current estimates by 
conducting sensitivity analyses. These include the impact of IDSE 
monitoring and the possibility that the primary analysis overestimates 
the compliance forecast for small surface water systems and all ground 
water systems. A detailed discussion of these analyses can be found in 
chapter 7 of the Economic Analysis (USEPA 2003i).
    Last, EPA has recently proposed or finalized new regulations for 
arsenic, radon, and microbials in ground water systems (Ground Water 
Rule); Cryptosporidium in small surface water systems and filter 
backwash in all system sizes (LT1ESWTR and Filter Backwash Rule); as 
well as concurrently proposing additional microbial control in surface 
water systems (Long Term 2 Enhanced Surface Water Treatment Rule). 
These rules may have overlapping impacts on some drinking water systems 
but it is not possible to estimate these 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, the total cost impact of these drinking water rules is 
uncertain; however, it may be less than the estimated total cost of all 
individual rules combined.

L. Benefit/Cost Determination for the Proposed Stage 2 DBPR

    The Agency has determined that the quantified and unquantified 
benefits of the proposed Stage 2 DBPR justify the costs. As discussed 
previously, the main concern for the Agency and the Advisory Committee 
involved in the Stage 2 rulemaking process was to address potential 
reproductive and developmental impacts associated with exposure to high 
DBP levels. The proposed rule achieves this objective using the least 
cost alternative by modifying how the annual average DBP level is 
calculated. This will reduce both average DBP levels associated with 
bladder cancer (and possibly other cancers) and peak DBP levels which 
are potentially associated with reproductive and developmental effects. 
In addition, this rule may reduce uncertainty about drinking water 
quality and may allow some systems to avoid installing additional 
technology to meet future drinking water regulations.
    Compared to other rule options consider by the Agency, the proposed 
rule option is also the most cost-effective. The cost-effectiveness 
analysis compares the annual dollar cost of the rule to the annual 
number of bladder cancer cases potentially avoided. For bladder cancer 
reduction, the cost per case avoided for the proposed rule would be 
$0.3 million if the PAR is 17%, and $3.1 million if the PAR is 2%, and 
also varies depending on the discount rate used.

M. Request for Comment

    The Agency requests comment on all aspects of the rule's economic 
impact analysis. Specifically, EPA seeks input into the following 
issues: (1) To what extent can systems install treatment to address 
multiple contaminants?; (2) Are there methods for monetizing potential 
reproductive and developmental endpoints associated with DBP exposure?; 
(3) To what extent will use of chloramination increase levels of NDMA 
and potentially associated health risks, and how should this be 
considered in this rule making; and (4) How should the Agency value 
nonfatal cancers? Specifically, EPA uses a range of severities to 
calculate the WTP estimate to avoid a case of chronic bronchitis. 
Should the Agency only consider the most severe case of chronic 
bronchitis as a better proxy for a non-fatal cancer? Also, should the 
Agency use the risk-risk trade-off estimate of WTP to avoid a case of 
chronic bronchitis instead of the risk-dollar trade-off estimate (see 
the EA (USEPA 2003i) for a complete discussion of these issues)?

VIII. 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 ICR No. 2068.01 (USEPA 2003m).
    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 Stage 2 DBPR promulgation, the major information 
requirements involve monitoring activities, which include conducting 
the IDSE and submission of the IDSE report, and tracking compliance. 
The information collection requirements are mandatory (Part 141), and 
the information collected is not confidential.
    The estimate of annual average burden hours for the Stage 2 DBPR 
for systems and States is 248,568 hours. This estimate covers the first 
three years of the Stage 2 DBPR and includes implementation of Stage 2A 
and most of the IDSE (small system reports are not due until the fourth 
year). The annual average aggregate cost estimate is $18.0 million for 
operation and maintenance as a purchase of service for lab work, and 
$6.8 million is associated with labor. The annual burden hour per 
response is 2.59 hours. The frequency of response (average responses 
per respondent) is 11.8 annually. The estimated number of likely 
respondents is 8,131 per year (the product of burden hours per 
response, frequency, and respondents does not total the annual average 
burden hours due to rounding). Because disinfecting systems have 
already purchased basic monitoring equipment to comply with the Stage 1 
DBPR, EPA assumes no capital start-up costs are associated with the 
Stage 2 DBPR ICR.
    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

[[Page 49649]]

needed to review instructions; develop, acquire, install, and utilize 
technology 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-2002-0043. 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 18, 2003, a comment to OMB is best assured of having its 
full effect if OMB receives it by September 17, 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 Analysis (RFA), as amended by the Small 
Business Regulatory Enforcement Fairness Act (SBREFA) of 1996, 5 U.S.C. 
601 et seq., generally requires an agency to prepare a regulatory 
flexibility analysis of any rule subject to notice and comment 
rulemaking requirements under the Administrative Procedure Act or any 
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. 601(3) through (5). In 
addition to the above, to establish an alternative small business 
definition, agencies must consult with SBA's Chief Counsel 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 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 75 small systems using surface water or ground water 
under the direct influence of surface water (GWUDI), which are 1.67% of 
all such systems affected by the Stage 2 DBPR, will experience an 
impact of greater than or equal to 1% of their revenues, and 49 small 
systems using surface water or GWUDI, which are 1.09% of all such 
systems affected by the Stage 2 DBPR, will experience an impact of 
greater than or equal to 3% of their revenues; further, 109 small 
ground water systems, which are 0.28% of all such systems affected by 
the Stage 2 DBPR, will experience an impact of greater than or equal to 
1% of their revenues, and 38 small ground water systems, which are 
0.10% of all such systems affected by the Stage 2 DBPR, will experience 
an impact of greater than or equal to 3% of their revenues (see Tables 
VIII-1 and VIII-2).
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BILLING CODE 6560-50-C
    As a result of the input received from stakeholders, the EPA 
workgroup, the Advisory Committee, and other interested parties, EPA 
has developed MCLs using locational running annual averages (LRAA) of 
0.080 and 0.060 mg/L for TTHM and HAA5 respectively, in combination 
with Initial Distribution Systems Evaluations (IDSE), as the preferred 
Stage 2 DBPR option. LRAAs are running annual averages calculated for 
each sample location in the distribution system. Since many small 
systems only monitor at one location, they will effectively base their 
compliance with the Stage 1 DBPR on an LRAA and therefore will not be 
significantly affected by the Stage 2 DBPR. In addition to meeting the 
MCLs for TTHM and HAA5, systems will be required to conduct IDSEs. The 
purpose of the IDSE is to identify compliance monitoring sites 
representing high TTHM and HAA5 levels in the distribution system. 
According to the Stage 2 DBPR Economic Analysis (USEPA 2003i), only 17% 
of all small water systems will conduct IDSE monitoring because small 
NTNCWSs are exempt from IDSE monitoring, systems serving fewer than 500 
people may receive a waiver from their States, and other systems are 
eligible for a 40/30 certification if all compliance monitoring samples 
have been <= 0.040 and <= 0.030 mg/L for TTHM and HAA5 respectively 
during the previous two years. A large number of small ground water 
systems will qualify for this certification. This provision is 
described in more detail in section V.H. of this preamble.
    Although not required by the RFA to convene a Small Business 
Advocacy

[[Page 49652]]

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 
SERs likely to be impacted by the Stage 2 M-DBP Rules. The SERs 
included small system operators, local government officials, and small 
nonprofit organizations. The SERs were provided with background 
information on the Safe Drinking Water Act, Stage 1 DBPR, IESWTR, and 
Stage 2 DBPR alternatives and unit cost analyses resulting from using 
different technologies to meet the required MCLs in preparation for the 
teleconferences on January 28, 2000, February 25, 2000, and April 7, 
2000. This information package included data on options and preliminary 
unit costs for treatment enhancements under consideration. It is 
important to note that, since EPA did not consider the IDSE 
requirements until after these consultations with SERs and the SBAR 
panel, no comments were received on the IDSE requirements from the SERs 
or the SBAR panel. However, small system representatives were included 
in the Advisory Committee that recommended the IDSE.
    During these conference calls, the information was discussed and 
EPA provided feedback and noted these initial SER comments. Following 
the calls, the SERs were asked to provide input on the potential 
impacts of the rule. Seven SERs provided written comments on these 
materials. These comments were provided to the SBAR Panel when the 
Panel convened in April 25, 2000. After a teleconference between the 
SERs and the Panel on May 25, 2000, the SERs were invited to provide 
additional comments on the information provided. Seven SERs provided 
additional comments on the rule components.
    In general, the SERs consulted on the Stage 2 M-DBP rules were 
concerned about the impact of these proposed rules on small water 
systems. They were particularly concerned with acquiring the technical 
and financial capability to implement requirements, maintaining 
flexibility to tailor requirements to their needs, and the limitations 
of small systems.
    The Small Business Advocacy Review (SBAR) Panel members for the 
Stage 2 DBPR were: the Small Business Advocacy Chair of the 
Environmental Protection Agency, the Chief of the Standards and Risk 
Reduction Branch of the Office of Ground Water and Drinking Water 
within EPA's Office of Water, the Administrator of the Office of 
Information and Regulatory Affairs within the Office of Management and 
Budget, and the Chief Counsel for Advocacy of the Small Business 
Administration. The Panel convened on April 25, 2000, and met five 
times before the end of the 60-day Panel period on June 23, 2000. 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)'', the Small Entity Representatives (SERs) comments on 
components of the Stage 2 MDBP Rules, and the background information 
provided to the SBAR Panel and the SERs are available for review in the 
Office of Water Docket.
    Today's proposal takes into consideration the recordkeeping and 
reporting concerns identified by the Panel and the SERs. The Panel 
recommended that EPA evaluate ways to minimize the rule recordkeeping 
and reporting burdens by ensuring that States have appropriate capacity 
for rule implementation and that EPA provide as much monitoring 
flexibility as possible to small systems. Continuity with the Stage 1 
DBPR was maintained to the extent possible to ease the transition to 
the Stage 2 DBPR, especially for small systems. EPA's decision to 
maintain the same MCLs for TTHM and HAA5 will also help to minimize the 
additional implementation burden. Generally, routine monitoring will be 
similar in frequency to monitoring for the Stage 1 DBPR, and systems 
with low DBP levels will still be eligible for reduced monitoring. Many 
small systems will conduct the same amount of monitoring for the Stage 
2 DBPR as for the Stage 1 DBPR. Surface and ground water community 
water systems (CWSs) serving 500 to 9,999 people and ground water 
systems serving at least 10,000 people may be required to add one 
sampling site and take an additional quarterly TTHM/HAA5 sample at that 
site. Also, EPA has specified consecutive system requirements; these 
will be new requirements in States where consecutive systems are not 
required to comply with some or all Stage 1 DBPR requirements. As noted 
before, since some small systems will be effectively complying with 
such requirements under the Stage 1 DBPR, the Stage 2 DBPR will not 
impose any additional burden on them.
    The Panel also noted the concern of several SERs that flexibility 
should be provided in the compliance schedule of the rule. SERs noted 
the technical and financial limitations that some small systems will 
have to address, 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 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 the SDWA. EPA 
believes that the proposed compliance schedules provides sufficient 
time for small systems to achieve compliance.
    Under the proposed LT2ESWTR, certain subpart H systems with low 
levels of indicators such as E. coli will not have to monitor for 
Cryptosporidium. The efficacy of E. coli as an indicator will be 
evaluated using the large system data. Thus, small systems E. coli 
monitoring cannot be initiated until large and medium system monitoring 
has been completed. The LT2ESWTR compliance time line for small systems 
thus lags 1.5 to 2.5 years behind the large and medium systems; 
timeline. Because the Stage 2 DBPR must be implemented on a 
simultaneous schedule, the compliance timeline is similarly delayed 1.5 
to 2.5 years behind large and medium systems. In addition, if capital 
improvements are necessary for a particular PWS to comply, a State may 
allow the system up to an additional two years to comply with the MCL. 
The Agency is developing guidance manuals to assist small entities with 
their compliance efforts.
    The Panel considered a wide range of options and regulatory 
alternatives for providing small businesses with flexibility in 
complying with the Stage 2 DBPR. The Panel recognized the concern 
shared by most stakeholders regarding the need to reduce DBP 
variability in the distribution system. This concern comes from recent 
studies that, while not conclusive, suggest that there may be adverse 
reproductive effects associated with relatively short-term exposure to 
high levels of DBPs. Many small systems will be monitoring at only a 
single point in the distribution system (designed to represent the 
point of maximum TTHM and HAA5 exposure), and many small systems will 
be monitoring only once during the year, at a time which corresponds to 
the season with the highest potential occurrence.

[[Page 49653]]

    Since there is a chance for this single sample to exceed an MCL, 
today's proposal requires systems that exceed an MCL on an annual or 
less frequent sample to begin increased (quarterly) monitoring rather 
than immediately being in violation of the MCL. The system must comply 
with the MCL as an LRAA once it has collected four quarterly samples. 
This allows small systems to generally monitor less frequently (to 
reduce their monitoring burden) during the period when the highest DBP 
levels are expected (to protect public health) without penalizing them 
(by requiring them to meet an MCL that would effectively be based on a 
single highest value if the systems were immediately in violation after 
a single sample exceeds an MCL). This compliance determination is 
consistent with requirements for systems that monitor quarterly for 
whom compliance is based on the compliance monitoring results of the 
previous four quarters.
    It is important to note that based on the IDSE results, some small 
systems will have a high TTHM site that is different from the high HAA5 
site. These systems will need to monitor at two sites under the Stage 2 
DBPR. EPA believes that an approach based on compliance with 0.080 mg/L 
TTHM and 0.060 mg/L HAA5 LRAAs is an effective way of addressing 
concerns regarding locational variability.
    In addressing seasonal variability, the Panel was concerned about a 
regulatory alternative requiring compliance with 0.080 mg/L TTHM and 
0.060 mg/L HAA5 single highest value MCL (Alternative 2), because it 
would impose significant additional cost on some small systems. The 
Panel recommended that EPA instead explore an approach under which 
individual high values might trigger additional assessment and/or 
notification requirements, rather than an MCL violation.
    EPA agrees with the panel recommendations on a single highest value 
MCL. Under today's proposal, public water systems are required to 
maintain a record of TTHM and HAA5 concentrations detected at each 
sample location. As part of the sanitary survey process, systems are 
required to conduct an evaluation and consult with their State 
regarding significant excursions in TTHM and HAA5 occurrence that have 
occurred. EPA is developing guidance for public water systems and 
States on how to identify significant excursions and conduct 
significant excursion evaluations, and how to reduce DBP levels through 
actions such as distribution system operational changes (USEPA 2003n) 
(Section V.E.).
    The Panel noted the strong concerns expressed by some SERs about 
the uncertainty in the current scientific evidence regarding health 
effects from exposure to DBPs, particularly regarding short term 
exposure. A Panel member recommended that EPA give further serious 
consideration to making a determination that the currently available 
scientific evidence does not warrant imposing additional regulatory 
requirements beyond those in the Stage 1 DBPR at this time. This Panel 
member recommended that EPA instead continue to vigorously fund ongoing 
research in health effects, occurrence, and appropriate treatment 
techniques for DBPs, and reconsider whether additional requirements are 
appropriate during its next SDWA required six-year review of the 
standard. This panel member also recommended that EPA separately 
explore whether adequate data exist to warrant regulation of NTNCWSs at 
a national level at this time.
    EPA has considered these recommendations and believes the Stage 2 
DBPR is needed at this time to protect public health. EPA's main 
mission is the protection of human health and the environment. When 
carrying out this mission, EPA must often make regulatory decisions 
with less than complete information and with uncertainties in the 
available information. EPA believes it is appropriate and prudent to 
err on the side of public health protection when there are indications 
that exposure to a contaminant may present risks to public health, 
rather than take no action until risks are unequivocally proven. 
Therefore, while recognizing the uncertainties in the available 
information, EPA believes that the weight of evidence represented by 
the available epidemiology and toxicology studies on chlorinated water 
and DBPs supports a hazard concern and a protective public health 
approach to regulation. In addition, EPA has an ongoing research 
program to study DBP health effects, occurrence, and treatment.
    EPA continues 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

    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 UMRA section 202, 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 by State, local, and Tribal governments, in 
the aggregate, or by 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.
    EPA has determined that this rule does not contain 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. Based on total estimated nominal costs incurred 
by year, costs for public or private systems are not expected to exceed 
$100 million in any one year. In addition, total estimated annualized 
costs of this rule are $59 to $65 million for all systems, including 
labor burdens that States would face, such as training employees on the 
requirements of the Stage 2 DBPR, responding to PWS reports, and record 
keeping. Thus, today's proposed rule is not subject to the requirements 
of sections 202 and 205 of the UMRA.
    EPA has determined that the Stage 2 DBPR contains no regulatory 
requirements that might significantly or uniquely affect small 
governments (see Tables VIII-1 and VIII-2). Since the Stage 2 DBPR 
affects all size systems

[[Page 49654]]

and the impact on small entities will be 0.00 to 0.11 percent of 
revenues, the Stage 2 DBPR is not subject to the requirements of 
section 203 of UMRA.
    Nevertheless, in developing this rule, EPA consulted with small 
governments (see sections VIII.B., VIII.C. and VIII.F.). In preparation 
for the proposed Stage 2 DBPR, EPA conducted an analysis of small 
government impacts and included small government officials or their 
designated representatives in the rulemaking process. As noted 
previously, a variety of stakeholders, including small governments, had 
the opportunity for timely and meaningful participation in the 
regulatory development process through the SBREFA process, public 
stakeholder meetings, and Tribal meetings. Representatives of small 
governments took part in the SBREFA process for this rulemaking and 
they attended public stakeholder meetings. Through such participation 
and exchange, EPA notified several potentially affected small 
governments of requirements under consideration and provided officials 
of affected small governments with an opportunity to have meaningful 
and timely input into the development of this regulatory proposal.
    The Agency has developed fact sheets that describe requirements of 
the proposed Stage 2 DBPR. These fact sheets are available by calling 
the Safe Drinking Water Hotline at 800-426-4791.

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.''
    This proposed rule will not have federalism implications. It will 
not impose 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, as specified in Executive Order 13132. The proposed rule 
has one-time costs for implementation of approximately $68.5 million. 
Thus, Executive Order 13132 does not apply to this rule.
    Although Executive Order 13132 does not apply to this rule, EPA did 
consult with State and local officials in developing this proposed 
regulation. On February 20, 2001, EPA held a dialogue on both the Stage 
2 DBPR and LT2ESWTR with representatives of State and local 
governmental organizations including those that represent elected 
officials. Representatives from the following organizations attended 
the consultation meeting: 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. 
At the consultation meeting, questions ranged from a basic inquiry into 
how Cryptosporidium gets into water to more detailed queries about 
anticipated implementation guidance, procedures, and schedules. No 
concerns were expressed. Some of the State and local organizations who 
attended the governmental dialogue on upcoming microbial and 
disinfection byproduct rulemakings were also participants in the 
Advisory Committee meetings and signed the Agreement in Principle. In 
addition, EPA consulted with a mayor in the SBREFA consultation 
described in section VIII B.
    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 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.
    Total Tribal costs are estimated to be approximately $199,372 per 
year (at a 3 percent discount rate) and this cost is distributed across 
559 Tribal systems. The cost for individual systems depend on system 
size and source water type. Of the 559 Tribes that may be affected in 
some form by the Stage 2 DBPR, 502 use ground water as a source and 57 
systems use surface water or GWUDI. Since the majority of Tribal 
systems are ground water systems serving fewer than 500 people, less 
than 10 percent of all Tribal systems will likely have to conduct an 
IDSE. As a result, the Stage 2 DBPR is most likely to have an impact on 
Tribes using surface water or GWUDI serving more than 500 people. 
Accordingly, EPA provides the following Tribal summary impact statement 
as required by section 5(b) of Executive Order 13175. EPA provides 
further detail on Tribal impact in the Economic Analysis for the Stage 
2 Disinfectants and Disinfection Byproduct Rule (USEPA 2003i).
    EPA consulted with Tribal officials early in the process of 
developing this regulation to permit them to have meaningful and timely 
input into its development. Consistent with Executive Order 13175, EPA 
engaged in outreach and consultation efforts with Tribal officials in 
the development of this proposed regulation. The most long-term 
participation of Tribes was on the Advisory Committee through a 
representative of the All Indian Pueblo Council (AIPC), which is 
associated with approximately 20 Tribes.
    In addition to obtaining Tribal input during the Advisory Committee 
negotiations, EPA presented the Stage 2 DBPR at the 16th Annual 
Consumer Conference of the National Indian Health Board, the 
Environmental Council's Annual Conference, and the EPA/Inter-Tribal 
Council of Arizona, Inc. Over 900 attendees representing Tribes from 
across the country attended the National Indian Health Board's Consumer 
Conference and over 100

[[Page 49655]]

Tribes were represented at the annual conference of the National Tribal 
Environmental Council. Representatives from 15 Tribes participated at 
the EPA/Inter-Tribal Council of Arizona meeting. At the first two 
conferences, an EPA representative conducted workshops on EPA's 
drinking water program and upcoming regulations, including the Stage 2 
DBPR. EPA sent the presentation materials and a meeting summary to over 
500 Tribes and Tribal organizations.
    Fact sheets describing the requirements of the proposed rule 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 fact sheets on the Stage 2 DBPR to all of the federally 
recognized Tribes in November 2000, as well as the Tribal Caucus of the 
National Tribal Operations Committee.
    A few Tribes responded by requesting more information and 
expressing concern about having to implement too many regulations. Some 
members of the Tribal Caucus noted that the rule would have a benefit. 
They also expressed a concern about infrastructure costs and the lack 
of funding attached to the rule. In response to one Tribal 
representative's comments on the November 2000 mailout, EPA explained 
the health protection benefit expected to be gained by this proposed 
rule. EPA also directed those who asked for more information to the 
Agreement in Principle on the EPA Web site.
    EPA also held a teleconference for Tribal representatives on 
January 24, 2002. Prior to the teleconference, invitations were sent to 
all of the Federally-recognized Tribes, along with fact sheets 
explaining the rule. Twelve Tribal representatives and four regional 
Tribal Program Coordinators attended. The Tribal representatives 
requested further explanation of the rule and expressed concerns about 
funding sources. EPA also received calls from Tribes after the 
teleconference which provided EPA with further feedback. In the spirit 
of Executive Order 13175, and consistent with EPA policy to promote 
consultation 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.
    While this proposed rule is not subject to the Executive Order 
because it is not economically significant as defined in Executive 
Order 12866, EPA nonetheless has reason to believe that the 
environmental health or safety risk (i.e., the risk associated with 
DBPs) addressed by this action may have a disproportionate effect on 
children. As a matter of EPA policy, we have therefore assessed the 
environmental health or safety effect of DBPs on children. EPA has 
consistently and explicitly considered risks to infants and children in 
all assessments developed for this rulemaking. The results of the 
assessments are contained in section III of this preamble, Health Risks 
to Fetuses, Infants, and Children: A Review (USEPA 2003a), and in the 
Economic Analysis (USEPA 2003i). A copy of all documents has been 
placed in the public docket for this action.
    EPA's Office of Water has historically considered risks to 
sensitive subpopulations (including fetuses, infants, and children) in 
establishing drinking water assessments, health advisories or other 
guidance, and standards (USEPA 1989c and USEPA 1991a). Waterborne 
disease from pathogens in drinking water is a major concern for 
children and other subgroups (elderly, immune compromised, pregnant 
women) because of their increased vulnerabilities (Gerba et al. 1996). 
There is a concern for potential reproductive and developmental risks 
posed by DBPs to children and pregnant women (USEPA 1994b; USEPA 1998c, 
Reif et al. 2000; Tyl, 2000). Specific to this action, human 
epidemiology and animal toxicology studies on DBPs have shown potential 
increased risks for spontaneous abortion, still birth, neural tube 
defects, cardiovascular effects and low birth weight. This rule is 
designed to lower those risks. EPA has provided an illustrative 
calculation of potential fetal losses avoided in section VII.C.1.
    Section V.D of this preamble presents the regulatory alternatives 
that EPA evaluated for the proposed Stage 2 DBPR, and the Economic 
Analysis (USEPA 2003i) provides a more detailed discussion. The Agency 
considered four alternatives involving different MCLs and different 
compliance calculations. The proposed alternative was recommended by 
the Advisory Committee and selected by EPA as the Preferred Regulatory 
Alternative because it provides significant public health benefits for 
an acceptable cost. EPA's analysis of benefits and costs indicates that 
the proposed alternative is superior among those evaluated with respect 
to maximizing net benefits, as shown in the Economic Analysis (USEPA 
2003i). The result of the Stage 2 DBPR may include a reduction in 
reproductive and developmental risk to children and pregnant women and 
a reduction in cancer risk.
    It should also be noted that the LT2ESWTR, which will be 
implemented at the same time as this proposed rule, provides better 
controls of pathogens and achieves the goal of increasing microbial 
drinking water protection for children. 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 DBPs.

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

    The proposed Stage 2 DBPR 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 Stage 2 DBPR would adversely 
affect the supply of energy. The Stage 2 DBPR does not regulate power 
generation, either directly or indirectly. The public and private 
utilities that the Stage 2 DBPR regulates do not, as a rule, generate 
power. Further, the cost increases borne by customers of water 
utilities as a result of the Stage 2 DBPR are a low percentage of the 
total cost of water, except for a very few small systems that might 
install advanced technologies that must spread that cost over a narrow 
customer base. Therefore,

[[Page 49656]]

the customers that are power generation utilities are unlikely to face 
any significant effects as a result of the Stage 2 DBPR. In sum, the 
Stage 2 DBPR does not regulate the supply of energy, does not generally 
regulate the utilities that supply energy, and is unlikely 
significantly to affect the customer base of energy suppliers. Thus, 
the Stage 2 DBPR would not translate into adverse effects on the supply 
of energy.
    The second consideration is whether the Stage 2 DBPR would 
adversely affect the distribution of energy. The Stage 2 DBPR does not 
regulate any aspect of energy distribution. The utilities that are 
regulated by the Stage 2 DBPR 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 0.007 
percent. Therefore, EPA estimates that the existing connections are 
adequate and that the Stage 2 DBPR has no discernable adverse effect on 
energy distribution.
    The third consideration is whether the Stage 2 DBPR 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 Stage 2 DBPR 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 
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 Stage 2 DBPR, 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 Stage 2 
DBPR. Energy use is not directly stated in Technologies and Costs for 
Control of Microbial Contaminants and Disinfection By-Products (USEPA 
2003k), but the annual cost of energy for each technology addition or 
upgrade necessitated by the Stage 2 DBPR 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/ kilowatt hours per year (kWh/yr) (U.S. Department of Energy, 
Energy Information Administration (USDOE EIA) 2002). These calculations 
are shown in detail in Chapter 8 of the Economic Analysis for the Stage 
2 DBPR (USEPA 2003i). 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. Table VIII-3 shows the estimated energy 
use for each Stage 2 DBPR compliance technology in kilowatt hours per 
year (kWh/yr). The incremental national annual energy usage is 0.08 
million megawatt-hours (mWh).
[GRAPHIC] [TIFF OMITTED] TP18AU03.023

    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 VIII-3 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 mWh of electricity in 2001 (USDOE EIA 2002). Therefore, 
even using the highest assumed energy use for the Stage 2 DBPR, the 
rule when fully implemented would result in only a 0.002 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

[[Page 49657]]

incremental power demand by water utilities.
    Both energy use and water use peak 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 
8.3 mW. A more detailed derivation of this value is shown in Chapter 8 
of the Economic Analysis for the Stage 2 DBPR (USEPA 2003i). 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 16.6 mW could be needed for treatment 
technologies installed to comply with the Stage 2 DBPR. This is only 
0.014 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, and use. While certain areas, notably California, 
have experienced shortfalls in generating capacity in the recent past, 
a peak incremental power requirement of 16.6 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 
Stage 2 DBPR will not have any significant effect on the use of energy, 
based on annual average use and on conditions of peak power demand.

I. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act (NTTAA) of 1995, Pub. L. No. 104-113, 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., materials 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.
    This proposed rulemaking involves technical standards. EPA proposes 
to use American Society for Testing and Materials (ASTM) Method D 6581-
00 for chlorite, bromide, and bromate compliance monitoring, which can 
be found in the Annual Book of ASTM Standards Volume 11.01. In the 
Stage 1 DBPR, EPA approved 13 methods from the Standard Methods 
Committee for measuring disinfectants, DBPs, and other parameters. 
Today's rule proposes to add the most recent versions of these 13 
methods as approved methods. These consist of Standard Methods 4500-Cl 
D, 4500-Cl F, 4500-Cl G, 4500-Cl E, 4500-Cl I, 4500-Cl H, 4500-
ClO2 D, 4500-ClO2 E, 6251 B, 5310 B, 5310 C, 5310 
D, and 5910 B for chlorine, chlorine dioxide, HAA5, chlorite, TOC/DOC, 
and UV254. These methods can be found in the 19th and 20th 
editions of Standard Methods for the Examination of Water and Waste 
Water (APHA 1995; APHA 1996; APHA 1998). Standard Methods 4500-Cl D, 
4500-Cl F, 4500-Cl G, 4500-Cl E, 4500-Cl I, 4500-Cl H, 4500-
ClO2 E, 6251 B, 5310 B, 5310 C, 5310 D, and 5910 B for 
chlorine, chlorine dioxide, HAA5, chlorite, TOC/DOC, and 
UV254 are also available in the On-Line Version of Standard 
Methods for the Examination of Water and Waste Water (APHA 2003).
    EPA welcomes comments on this aspect of the proposed rulemaking 
and, specifically, invites the public to identify 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 Stage 2 DBPR 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 Stage 1 DBPR has served as a template for the development of 
the Stage 2 DBPR. As such, the Agency built on the efforts conducted 
during the development of the Stage 1 DBPR 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 Stage 2 DBPR 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 Stage 2 DBPR serves to provide a similar level of 
drinking water protection to all groups. Where water systems have high 
DBP levels, they must reduce levels to meet the MCLs. Thus, the Stage 2 
DBPR meets the intent of Federal policy requiring incorporation of 
environmental justice into Federal agency missions.
    The Stage 2 DBPR applies uniformly to community water systems and 
nontransient noncommunity water systems that apply a chemical 
disinfectant or deliver water that has been chemically disinfected. 
Consequently, the health protection from DBP exposure that this rule 
provides is equal across all income and minority groups served by 
systems regulated by this rule.

[[Page 49658]]

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 Stage 2 
DBPR during the public comment period.
    EPA met with the SAB to discuss the Stage 2 DBPR 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 met with the NDWAC on 
November 8, 2001, in Washington, DC to discuss the Stage 2 DBPR 
proposal. The Advisory Committee generally supported the need for the 
Stage 2 DBPR based on health and occurrence data, but also stressed the 
importance of providing flexibility to the systems implementing the 
rule. The results of these discussions are included in the docket for 
this rule.

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?

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USEPA 1989c. Review of Environmental Contaminants and Toxicology. 
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225 pp.
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Organic Chemicals and Inorganic Chemicals; Monitoring for 
Unregulated Contaminants; National Primary Drinking Water 
Regulations Implementation; National Secondary Drinking Water 
Regulations. Final rule, January 31, 1991. FR 56:20: 3526.
USEPA 1991b. Guidelines for Developmental Toxicity Risk Assessment. 
FR 56:234:63798-63826.
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USEPA 1997a. National Primary Drinking Water Regulations; 
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Availability; Proposed Rule. FR 62:212:59388-59484. (November 3, 
1997).
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USEPA 1998c. National Primary Drinking Water Regulations: 
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63:241:69390-69476. (December 16, 1998). http://www.epa.gov/safewater/mdbp/dbpfr.pdf
USEPA 1998d. National Primary Drinking Water Regulations: Interim 
Enhanced Surface Water Treatment Rule; Final Rule. FR 63:241:38832-
38858. (December 16, 1998). http://www.epa.gov/safewater/mdbp/ieswtrfr.pdf
USEPA 1998e. National Primary Drinking Water Regulations; 
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Availability; Proposed Rule. FR 63:61:15606-15692. (March 31, 1998).
USEPA 1998f. Regulatory Impact Analysis of Final Disinfectant/
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815-B-98-002. PB 99-111304.
USEPA 1998g. National-Level Affordability Criteria Under the 1996 
Ammendments to the Safe Drinking Water Act (Final Draft Report). 
Contact 68-C6-0039. (August 19, 1998).
USEPA 1998h. Variance Technology Findings for Contaminants Regulated 
Before 1996. Office of Water. EPA 815-R-98-003.
USEPA 1998i. National Primary Drinking Water Regulations: Consumer 
Confidence Reports; Final Rule. FR 63:160:44512-44536.
USEPA 1998j. Revisions to State Primacy Requirements to Implement 
Safe Drinking Water Act Amendments; Final Rule. FR 63:81:23362-
23368.
USEPA 1999a. Guidelines for carcinogen risk assessment. July SAB 
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USEPA NCEA-F-0644. http://www.epa.gov/ncea/raf/crasab.htm
USEPA 1999b. National Primary and Secondary Drinking Water 
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Contaminants and Revisions to Laboratory Certification Requirements; 
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USEPA 1999c. Chloroform Mode of Action Analysis. Prepared for the 
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of Water. October 1999. http://www.epa.gov/sab/chloro00.htm
USEPA 1999d. Cost of Illness Handbook. Office of Pollution 
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USEPA 2000c. Information Collection Rule Auxiliary 1 Database, 
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USEPA 2000d. EPA Method 321.8. In Methods for the Determination of 
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USEPA 2000e. Removal of the Maximum Contaminant Level Goal for 
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USEPA 2000f. Review of the EPA's Draft Chloroform Risk Assessment by 
a Subcommittee of the Science Advisory Board. Science Advisory 
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USEPA 2000g. Stage 2 Microbial and Disinfection Byproducts Federal 
Advisory Committee Agreement in Principle. FR 65:251:83015-83024. 
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USEPA 2000h. National Primary Drinking Water Regulations: Ground 
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Office of Water, Office of Science and Technology, Health and 
Ecological Criteria Division, Washington, DC.

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USEPA 2000j. Drinking Water Baseline Handbook, Second Edition. 
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USEPA 2000k. Geometries and Characteristics of Public Water Systems. 
Final Report. EPA 815-R-00-024. December 2000.
USEPA 20001. EPA Method 300.1. In Methods for the Determination of 
Organic and Inorganic Compounds in Drinking Water, Volume 1. OW-
OGWDW-TSC, Cincinnati, OH. EPA 815-R-00-014. Available on the OGWDW 
Web site at http://www.epa.gov/safewater/methods/sourcalt.html.
USEPA 2000m. Information Collection Rule Treatment Study Database 
CD-ROM, Version 1.0.
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EEAC-00-013.
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USEPA 2001b. Toxicological Review of Chloroform. In support of 
Integrated Risk Information System (IRIS). Washington, DC. Draft. 
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USEPA 2001c. National Primary Drinking Water Regulations: Filter 
Backwash Recycling Rule. Final Rule. FR 66:111:31086-31105. (June 8, 
2001).
USEPA 2001d. Method 317.0, Revision 2.0. Determination of Inorganic 
Oxyhalide Disinfection By-Products in Drinking Water Using Ion 
Chromatography with the Addition of a Postcolumn Reagent for Trace 
Bromate Analysis. Revision 2.0. EPA 815-B-01-001. (Available on the 
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USEPA 2001e. Arsenic Rule Benefits Analysis: an SAB Review. August 
30, 2001. EPA-SAB-EC-01-008.
USEPA 2002a. Method 326.0. Determination of Inorganic Oxyhalide 
Disinfection By-Products in Drinking Water Using Ion Chromatography 
Incorporating the Addition of a Suppressor Acidified Postcolumn 
Reagent for Trace Bromate Analysis. Revision 1.0. EPA 815-R-03-007. 
(Available on the OGWDW Web site at http://www.epa.gov/safewater/methods/sourcalt.html.)
USEPA 2002b. Long Term 1 Enhanced Surface Water Treatment Rule. 
January 14, 2002. 67 FR 1812.
USEPA 2002c. Affordability Criteria for Small Drinking Water 
Systems: an EPA Science Advisory Board Report. December 2002. EPA-
SAB-EEAC-03-004.
USEPA 2003a. Health Risks to Fetuses, Infants, and Children: A 
Review. Office of Water, Office of Science and Technology, Health 
and Ecological Criteria Division.
USEPA 2003b. Addendum to the Criteria Document for Monochloroacetic 
Acid and Trichleoeacetic Acid: External Review Draft.
USEPA 2003c. Addendum to the Criteria Document for Dichloroacetic 
Acid: External Review Draft.
USEPA 2003d. Drinking Water Criteria Document for Brominated 
Trihalomethanes: External Review Draft.
USEPA 2003e. Drinking Water Criteria Document for Brominated 
Haloacetic Acids: External Review Draft.
USEPA 2003f. Drinking Water Criteria Document for Cyanogen Chloride, 
External Review Draft.
USEPA 2003g. Drinking Water Criteria Document for Glyoxal and 
Methylglyoxal: External Review Draft.
USEPA 2003h. Drinking Water Criteria Document for Haloacetonitriles: 
External Review Draft.
USEPA 2003i. Economic Analysis for the Proposed Stage 2 DBPR. 
Washington, DC. EPA 815-D-03-001.
USEPA 2003j. Draft Initial Distribution System Evaluation Guidance 
Manual. Washington, DC. EPA 815-D-03-002.
USEPA 2003k. Technologies and Costs for Control of Microbial 
Pathogens and Disinfection Byproducts. Prepared by the Cadmus Group 
and Malcolm Pirnie.
USEPA 2003l. Toxicologcal Review for Dichloroacetic Acid: Consensus 
Review Draft. http://www.epa.gov/iris/subst/0654.htm
USEPA 2003m. Information Collection Request. Washington, DC. EPA 
815-D-03-003.
USEPA 2003n. Draft Significant Excursion Guidance Manual. 
Washington, DC. EPA 815-D-03-004.
USEPA 2003o. Stage 2 Occurrence Assessment for Disinfectants and 
Disinfection Byproducts (D/DBPs). EPA 68-C-99-206.
USEPA 2003p. Method 552.3. Determination of Haloacetic Acids and 
Dalapon in Drinking Water by Liquid-liquid Extraction, 
Derivatization, and Gas Chromatography with Electron Capture 
Detection. Revision 1.0. (Available on the OGWDW Web site at http://www.epa.gov/safewater/methods/sourcalt.html.)
USEPA 2003q. Method 327.0. Determination of Chlorine Dioxide and 
Chlorite Ion in Drinking water Using Lissamine Green B and 
Horseradish Peroxidase with Detection by Visible Spectrophotometry. 
Revision 1.0. (Available on the OGWDW Web site at http://www.epa.gov/safewater/methods/sourcalt.html.)
USEPA 2003r. Method 415.3. Determination of Total Organic Carbon, 
and Specific UV Absorbance at 254 nm in Source Water and Drinking 
Water. Revision 1.0. NERL, Cincinnati, OH 45268.
USEPA 2003s. Arsenic in Drinking Water: Cessation Lag Model. 
Prepared by Sciences International. Contract No. 68-c-98-195. 
January, 2003.
Veeramachaneni, D.N.R., T.T. Higuchi, J.S. Palmer, and C.M. Kane. 
2000. Dibromoacetic Acid, a Disinfection By-product in Drinking 
Water, Impairs Sexual Function and Fertility in Male Rabbits. Paper 
presented at the annual meeting for the Society for the Study of 
Reproduction, Madison, Wisconsin.
Vena, JE, Graham, S, Freudenheim, J, Marshall, J, Zielezny, M, 
Swanson, M, Sufrin, G. 1993. Drinking water, fluid intake, and 
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and Jackson, P.E. 2001. A Collaborative Study of EPA Method 317.0 
for the Determination of Inorganic Oxyhalide Disinfection By-
Products in Drinking Water using Ion Chromatography with the 
Addition of a Postcolumn Reagent for Trace Bromate Analysis. Journal 
of Chromatographic Science. Vol 39 (255-259), June 2001.
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D.J. 2002. U.S. Environmental Protection Agency Method 326.0, a new 
method for monitoring inorganic oxyhalides and optimization of the 
postcolumn derivatization for the selective determination of trace 
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Exposure Assessment Methods on Risk Estimates in an Epidemiologic 
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Environmental Health Perspectives. 104 (1): 48-51.
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Yang, V., B. Cheng, S. Tsai, T. Wu, M. Lin M. and K. Lin. 2000. 
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American Water Works Association, Denver, CO.

List of Subjects

40 CFR Part 141

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

40 CFR Part 142

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

40 CFR Part 143

    Chemicals, Indians-lands, 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 ``Combined distribution system'', ``Consecutive 
system'', ``Consecutive system entry point'', ``Dual sample sets'', 
``Finished water'', ``Locational running annual average'', and 
``Wholesale system'' to read as follows:


Sec.  141.2  Definitions.

* * * * *
    Combined distribution system is the interconnected distribution 
system consisting of the distribution systems of wholesale systems and 
of the consecutive systems that receive finished water from those 
wholesale system(s).
* * * * *
    Consecutive system is a public water system that buys or otherwise 
receives some or all of its finished water from one or more wholesale 
systems, for at least 60 days per year.
    Consecutive system entry point is a location at which finished 
water is delivered at least 60 days per year from a wholesale system to 
a consecutive system.
* * * * *
    Dual sample set is a set of two samples collected at the same time 
and same location, with one sample analyzed for TTHM and the other 
sample analyzed for HAA5. Dual sample sets are collected for the 
purposes of conducting an IDSE under subpart U of this part and 
determining compliance with the TTHM and HAA5 MCLs under subpart V of 
this part.
* * * * *
    Finished water is water that is introduced into the distribution 
system of a public water system and is intended for distribution 
without further treatment, except that necessary to maintain water 
quality.
* * * * *
    Locational running annual average (LRAA) is the average of sample 
analytical results for samples taken at a particular monitoring site 
during the previous four calendar quarters.
* * * * *
    Stage 2A is the period beginning [date three years following 
publication of the final rule] until the dates specified in subpart V 
of this part for compliance with Stage 2B, during which systems must 
comply with Stage 2A MCLs in Sec.  141.64(b)(2).
* * * * *
    Wholesale system is a public water system that treats source water 
and then sells or otherwise delivers finished water to another public 
water system for at least 60 days per year. Delivery may be through a 
direct connection or through the distribution system of one or more 
consecutive systems.
    3. In Sec.  141.23, the table in paragraph (k)(1) is amended by 
revising entries 13, 18, 19, and 20; revising the undesignated text 
after the table; and adding a new footnote 19 to read as follows:


Sec.  141.23  Inorganic chemical sampling and analytical requirements.

* * * * *
    (k) Inorganic analysis:
* * * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
 Contaminant and methodology \13\      EPA              ASTM \3\           SM \4\ (18th, 19th ed.)       SM \4\ (20th ed.)                Other
--------------------------------------------------------------------------------------------------------------------------------------------------------
 
                                                                      * * * * * * *
13. Fluoride:
    Ion Chromatography...........   \6\ 300.0  D4327-97                   4110 B                     4110 B
                                   \19\ 300.1
    Manual Distill.; Color.        ..........  .                          4500-F B, D                4500-F B, D
     SPADNS..
    Manual Electrode.............  ..........  D1179-93B                  4500-F C                   4500-F C
    Automated Electrode..........  ..........  .                          .                          .                          380-75WE \11\
    Automated Alizarin...........  ..........  .                          4500-F E                   4500-F E                   129-71W \11\
 
                                                                      * * * * * * *
18. Nitrate:
    Ion Chromatography...........   \6\ 300.0  D4327-97                   4110 B                     4110 B                     B1011 \8\
                                   \19\ 300.1  .........................  .........................  .........................  ........................
    Automated Cadmium Reduction..   \6\ 353.2  D3867-90A                  4500-NO3 F                 4500-NO3 F                 ........................
    Ion Selective Electrode......  ..........  .                          4500-NO3 D                 4500-NO3 D                 601 \7\
    Manual Cadmium Reduction.....  ..........  D3867-90B                  4500-NO3 E                 4500-NO3 E                 ........................
19. Nitrite:
    Ion Chromatography...........   \6\ 300.0  D4327-97                   4110 B                     4110 B                     B-1011\8\
                                   \19\ 300.1  .........................  .........................  .........................  ........................
    Automated Cadmium Reduction..   \6\ 353.2  D3867-90A                  4500-NO3 F                 4500-NO3 F                 ........................
    Manual Cadmium Reduction.....  ..........  D3867-90B                  4500-NO3 E                 4500-NO3 E                 ........................
    Spectrophotometric...........  ..........  .........................  4500-NO2 B                 4500-NO2 B                 ........................
20. Orthophosphate: \12\

[[Page 49664]]

 
    Colorimetric, automated,         \6\365.1  .                          4500-P F                   4500-P F                   ........................
     ascorbic acid.
    Colorimetric, ascorbic acid,   ..........  D515-88A                   4500-P E                   4500-P E                   ........................
     single reagent.
    Colorimetric,                  ..........  .                          .                          .                          I-1601-85\5\
     phosphomolybdate.
    Automated-segmented flow.....  ..........  .                          .                          .                          I-2601-90\5\
    Automated discrete...........  ..........  .                          .                          .                          I-2598-85\5\
    Ion Chromatography...........   \6\ 300.0  D4327-97                   4110 B                     4110 B                     ........................
                                   \19\ 300.1  .........................  .........................  .........................  ........................
 
                                                                     * * * * * * *
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: The procedures shall be done in accordance with the documents listed below. The incorporation by reference of the following documents listed in
  footnotes 1-11 and 16-19 was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of the
  documents may be obtained from the sources listed below. Information regarding obtaining these documents can be obtained from the Safe Drinking Water
  Hotline at 800-426-4791. Documents may be inspected at EPA's Drinking Water Docket, EPA West, 1301 Constitution Avenue NW., Room B102, Washington, DC
  20460 (Telephone: 202-566-2426); or at the Office of the Federal Register, 800 North Capitol Street, NW., Suite 700, Washington, DC.
* * * * * * *
\3\ Annual Book of ASTM Standards, 1994, 1996, or 1999, Vols. 11.01 and 11.02, ASTM International; any year containing the cited version of the method
  may be used. The previous versions of D1688-95A, D1688-95C (copper), D3559-95D (lead), D1293-95 (pH), D1125-91A (conductivity) and D859-94 (silica)
  are also approved. These previous versions D1688-90A, C; D3559-90D, D1293-84, D1125-91A and D859-88, respectively are located in the Annual Book of
  ASTM Standards, 1994, Vol. 11.01. Copies may be obtained from ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428.
\4\ Standard Methods for the Examination of Water and Wastewater, 18th edition (1992), 19th edition (1995), or 20th edition (1998). American Public
  Health Association, 1015 Fifteenth Street, NW, Washington, DC 20005. The cited methods published in any of these three editions may be used, except
  that the versions of 3111 B, 3111 D, 3113 B and 3114 B in the 20th edition may not be used.
\5\ Method I-2601-90, Methods for Analysis by the U.S. Geological Survey National Water Quality Laboratory--Determination of Inorganic and Organic
  Constituents in Water and Fluvial Sediment, Open File Report 93-125, 1993; For Methods I-1030-85; I-1601-85; I-1700-85; I-2598-85; I-2700-85; and I-
  3300-85 See Techniques of Water Resources Investigation of the U.S. Geological Survey, Book 5, Chapter A-1, 3rd ed., 1989; Available from Information
  Services, U.S. Geological Survey, Federal Center, Box 25286, Denver, CO 80225-0425.
\6\ ``Methods for the Determination of Inorganic Substances in Environmental Samples'', EPA/600/R-93/100, August 1993. Available at NTIS, PB94-120821.
\7\ The procedure shall be done in accordance with the Technical Bulletin 601 ``Standard Method of Test for Nitrate in Drinking Water'', July 1994, PN
  221890-001, Analytical Technology, Inc. Copies may be obtained from ATI Orion, 529 Main Street, Boston, MA 02129.
\8\ Method B-1011, ``Waters Test Method for Determination of Nitrite/Nitrate in Water Using Single Column Ion Chromatography,'' August 1987. Copies may
  be obtained from Waters Corporation, Technical Services Division, 34 Maple Street, Milford, MA 01757.
* * * * * * *
\11\ Industrial Method No. 129-71W, ``Fluoride in Water and Wastewater'', December 1972, and Method No. 380-75WE, ``Fluoride in Water and Wastewater'',
  February 1976, Technicon Industrial Systems. Copies may be obtained from Bran & Luebbe, 1025 Busch Parkway, Buffalo Grove, IL 60089.
\12\ Unfiltered, no digestion or hydrolysis.
\13\ Because MDLs reported in EPA Methods 200.7 and 200.9 were determined using a 2X preconcentration step during sample digestion, MDLs determined when
  samples are analyzed by direct analysis (i.e., no sample digestion) will be higher. For direct analysis of cadmium and arsenic by Method 200.7, and
  arsenic by Method 3120 B sample preconcentration using pneumatic nebulization may be required to achieve lower detection limits. Preconcentration may
  also be required for direct analysis of antimony, lead, and thallium by Method 200.9; antimony and lead by Method 3113 B; and lead by Method D3559-90D
  unless multiple in-furnace depositions are made.
* * * * * * *
\19\ ``Methods for the Determination of Organic and Inorganic Compounds in Drinking Water'', Vol. 1, EPA 815-R-00-014, August 2000. Available at NTIS,
  PB2000-106981.

* * * * *
    4. Section 141.24 is amended by revising paragraph (e)(1) and by 
revising entry 30 in the table in paragraph (e)(1) to read as follows:


Sec.  141.24  Organic chemicals, sampling and analytical requirements.

* * * * *
    (e) * * *
    (1) The following documents are incorporated by reference. This 
incorporation by reference was approved by the Director of the Federal 
Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies 
may be inspected at EPA's Drinking Water Docket, 1301 Constitution 
Avenue, NW., EPA West, Room B102, Washington, DC 20460 (Telephone: 202-
566-2426); or at the Office of the Federal Register, 800 North Capitol 
Street, NW., Suite 700, Washington, DC. Method 508A and 515.1 are in 
Methods for the Determination of Organic Compounds in Drinking Water, 
EPA/600/4-88-039, December 1988, Revised, July 1991. Methods 547, 550 
and 550.1 are in Methods for the Determination of Organic Compounds in 
Drinking Water--Supplement I, EPA/600-4-90-020, July 1990. Methods 
548.1, 549.1, 552.1 and 555 are in Methods for the Determination of 
Organic Compounds in Drinking Water--Supplement II, EPA/600/R-92-129, 
August 1992. Methods 502.2, 504.1, 505, 506, 507, 508, 508.1, 515.2, 
524.2 525.2, 531.1, 551.1 and 552.2 are in Methods for the 
Determination of Organic Compounds in Drinking Water--Supplement III, 
EPA/600/R-95-131, August 1995. Method 1613 is titled ``Tetra-through 
Octa-Chlorinated Dioxins and Furans by Isotope-Dilution HRGC/HRMS'', 
EPA/821-B-94-005, October 1994. These documents are available from the 
National Technical Information Service, NTIS PB91-231480, PB91-146027, 
PB92-207703, PB95-261616 and PB95-104774, U.S. Department of Commerce, 
5285 Port Royal Road, Springfield, Virginia 22161. The toll-free number 
is 800-553-6847. Method 6651 shall be followed in accordance with 
Standard Methods for the Examination of Water and Wastewater, 18th 
edition (1992), 19th edition (1995), or 20th edition (1998), American 
Public Health Association (APHA); any of these three editions may be 
used. Method 6610 shall be followed in accordance with Standard Methods 
for the Examination of Water and Wastewater, (18th Edition Supplement) 
(1994), or with the 19th edition (1995) or 20th edition (1998) of 
Standard Methods for the Examination of Water and Wastewater; any of 
these publications may be used. The APHA documents are available from 
APHA, 1015 Fifteenth Street NW., Washington, D.C. 20005. Other required 
analytical test procedures germane to the conduct

[[Page 49665]]

of these analyses are contained in Technical Notes on Drinking Water 
Methods, EPA/600/R-94-173, October 1994, NTIS PB95-104766. EPA Methods 
515.3 and 549.2 are available from U.S. Environmental Protection 
Agency, National Exposure Research Laboratory (NERL)--Cincinnati, 26 
West Martin Luther King Drive, Cincinnati, OH 45268. ASTM Method D 
5317-93 is available in the Annual Book of ASTM Standards, (1999), Vol. 
11.02, ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 
19428, or in any edition published after 1993. EPA Method 515.4, 
``Determination of Chlorinated Acids in Drinking Water by Liquid-Liquid 
Microextraction, Derivatization and Fast Gas Chromatography with 
Electron Capture Detection,'' Revision 1.0, April 2000, EPA/815/B-00/
001 and EPA Method 552.3, ``Determination of Haloacetic Acids and 
Dalapon in Drinking Water by Liquid-Liquid Microextraction, 
Derivatization, and Gas Chromatography with Electron Capture 
Detection,'' Revision 1.0, July 2003 can be accessed and downloaded 
directly on-line at http://www.epa.gov/safewater/methods/sourcalt.html. The Syngenta AG-625, ``Atrazine in Drinking Water by 
Immunoassay'', February 2001 is available from Syngenta Crop 
Protection, Inc., 410 Swing Road, Post Office Box 18300, Greensboro, NC 
27419, Phone number (336) 632-6000. Method 531.2 ``Measurement of N-
methylcarbamoyloximes and N-methylcarbamates in Water by Direct Aqueous 
Injection HPLC with Postcolumn Derivatization,'' Revision 1.0, 
September 2001, EPA 815/B/01/002 can be accessed and downloaded 
directly on-line at http://www.epa.gov/safewater/methods/sourcalt.html.

----------------------------------------------------------------------------------------------------------------
             Contaminant                EPA method \1\    Standard methods         ASTM              Other
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
30. Dalapon.........................      552.1, 515.1,  .................  .................  .................
                                          552.2, 515.3,
                                           515.4, 552.3
 
                                                 * * * * * * *
----------------------------------------------------------------------------------------------------------------
\1\ For previously approved EPA methods which remain available for compliance monitoring until June 1, 2001, see
  paragraph (e)(2) of this section.

* * * * *
    5. Section 141.33 is amended by revising the first sentence of 
paragraph (a) introductory text, and adding paragraph (f) to read as 
follows:


Sec.  141.33  Record maintenance.

* * * * *
    (a) Records of microbiological analyses and turbidity analyses made 
pursuant to this part shall be kept for not less than 5 years. * * *
* * * * *
    (f) Copies of monitoring plans developed pursuant to this part 
shall be kept for the same period of time as the records of analyses 
are required to be kept under paragraph (a) of this section or for 
three years after modification, whichever is longer.
    6. Section 141.53 is amended by revising the table to read as 
follows:


Sec.  141.53  Maximum contaminant level goals for disinfection 
byproducts.

* * * * *

 
------------------------------------------------------------------------
           Disinfection byproduct                    MCLG (mg/L)
------------------------------------------------------------------------
Bromodichloromethane.......................  zero.
Bromoform..................................  zero.
Bromate....................................  zero.
Chlorite...................................  0.8
Chloroform.................................  0.07
Dibromochloromethane.......................  0.06
Dichloroacetic acid........................  zero.
Monochloroacetic acid......................  0.03
Trichloroacetic acid.......................  0.02
------------------------------------------------------------------------

    7. Section 141.64 is revised to read as follows:


Sec.  141.64  Maximum contaminant levels for disinfection byproducts.

    (a) Bromate and chlorite. The maximum contaminant levels (MCLs) for 
bromate and chlorite are as follows:

------------------------------------------------------------------------
                   Disinfection byproduct                     MCL (mg/L)
------------------------------------------------------------------------
Bromate....................................................        0.010
Chlorite...................................................        1.0
------------------------------------------------------------------------

    (1) Compliance dates for CWSs and NTNCWSs. Subpart H systems 
serving 10,000 or more persons must comply with this paragraph (a) 
beginning January 1, 2002. Subpart H systems serving fewer than 10,000 
persons and systems using only ground water not under the direct 
influence of surface water must comply with this paragraph (a) 
beginning January 1, 2004.
    (2) Best available technology. The Administrator, pursuant to 
section 1412 of the Act, hereby identifies the following as the best 
technology, treatment techniques, or other means available for 
achieving compliance with the maximum contaminant levels for bromate 
and chlorite identified in this paragraph (a):

------------------------------------------------------------------------
          Disinfection byproduct              Best available technology
------------------------------------------------------------------------
Bromate...................................  Control of ozone treatment
                                             process to reduce
                                             production bromate.
Chlorite..................................  Control of treatment
                                             processes to reduce
                                             disinfectant demand and
                                             control of disinfection
                                             treatment processes to
                                             reduce disinfectant levels.
------------------------------------------------------------------------

    (b) TTHM and HAA5.
    (1) Subpart L--RAA compliance. (i) Compliance dates. Subpart H 
systems serving 10,000 or more persons must comply with this paragraph 
(b)(1) beginning January 1, 2002 until the date specified for subpart V 
of this part compliance in Sec.  141.620(c). Subpart H systems serving 
fewer than 10,000 persons and systems using only ground water not under 
the direct influence of surface water must comply with this paragraph 
(b)(1) beginning January 1, 2004 until the date specified for subpart V 
of this part compliance in Sec.  141.620(c).

------------------------------------------------------------------------
                                                                MCL (mg/
                    Disinfection byproduct                         L)
------------------------------------------------------------------------
Total trihalomethanes (TTHM)..................................     0.080
Haloacetic acids (five) (HAA5)................................     0.060
------------------------------------------------------------------------

    (ii) Best available technology. The Administrator, pursuant to 
section 1412 of the Act, hereby identifies the following as the best 
technology, treatment techniques, or other means

[[Page 49666]]

available for achieving compliance with the maximum contaminant levels 
for TTHM and HAA5 identified in this paragraph (b)(1):

------------------------------------------------------------------------
          Disinfection byproduct              Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and            Enhanced coagulation or
 Halaocetic acids (five) (HAA5).             enhanced softening or
                                             GAC10, with chlorine as the
                                             primary and residual
                                             disinfectant.
------------------------------------------------------------------------

    (2) Stage 2A--LRAA compliance. (i) Compliance dates. The Stage 2A 
MCLs for TTHM and HAA5 must be complied with as a locational running 
annual average at each subpart L of this part compliance monitoring 
location under Sec.  141.136 beginning [date three years after 
publication of the final rule] until the date specified for subpart V 
of this part compliance in Sec.  141.620(c).

------------------------------------------------------------------------
                                                                MCL (mg/
                    Disinfection byproduct                         L)
------------------------------------------------------------------------
Total trihalomethanes (TTHM)..................................     0.120
Haloacetic acids (five) (HAA5)................................     0.100
------------------------------------------------------------------------

    (ii) Best available technology. The Administrator, pursuant to 
section 1412 of the Act, hereby identifies the following as the best 
technology, treatment techniques, or other means available for 
achieving compliance with the maximum contaminant levels for TTHM and 
HAA5 identified in this paragraph (b)(2):

------------------------------------------------------------------------
          Disinfection byproduct              Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and            Enhanced coagulation or
 Haloacetic acids (five) (HAA5).             enhanced softening or
                                             GAC10, with chlorine as the
                                             primary and residual
                                             disinfectant.
------------------------------------------------------------------------

    (3) Subpart V LRAA compliance. (i) Compliance dates. The subpart V 
of this part MCLs for TTHM and HAA5 must be complied with as a 
locational running annual average at each monitoring location beginning 
the date specified for Subpart V of this part compliance in Sec.  
141.620(c).

------------------------------------------------------------------------
                                                                MCL (mg/
                    Disinfection byproduct                         L)
------------------------------------------------------------------------
Total trihalomethanes (TTHM)..................................     0.080
Haloacetic acids (five) (HAA5)................................     0.060
------------------------------------------------------------------------

    (ii) Best technology for systems that disinfect their source water. 
The Administrator, pursuant to section 1412 of the Act, hereby 
identifies the following as the best technology, treatment techniques, 
or other means available for achieving compliance with the maximum 
contaminant levels for TTHM and HAA5 identified in this paragraph 
(b)(3) for all systems that disinfect their source water:

------------------------------------------------------------------------
          Disinfection byproduct              Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and            Enhanced coagulation or
 Haloacetic acids (five) (HAA5).             enhanced softening, plus
                                             GAC10; or nanofiltration
                                             with a molecular weight and
                                             cutoff <=1000 Daltons; or
                                             GAC20.
------------------------------------------------------------------------

    (iii) Best available technology for systems that buy disinfected 
water. The Administrator, pursuant to section 1412 of the Act, hereby 
identifies the following as the best technology, treatment techniques, 
or other means available for achieving compliance with the maximum 
contaminant levels for TTHM and HAA5 identified in this paragraph 
(b)(3) for systems that buy disinfected water:

------------------------------------------------------------------------
          Disinfection byproduct              Best available technology
------------------------------------------------------------------------
Total trihalomethanes (TTHM) and            Improved distribution system
 Haloacetic acids (five) (HAA5).             and storage tank management
                                             to reduce detention time
                                             plus the use of chloramines
                                             for disinfectant residual
                                             maintenance.
------------------------------------------------------------------------

    (c) Extensions. A system that is installing GAC or membrane 
technology to comply with the MCLs in paragraphs (a) or (b)(1) of this 
section may apply to the State for an extension of up to 24 months past 
January 1, 2002, but not beyond January 1, 2004. In granting the 
extension, States must set a schedule for compliance and may specify 
any interim measures that the system must take. Failure to meet the 
schedule or any interim treatment requirements constitutes a violation 
of a National Primary Drinking Water Regulation.

Subpart L--[Amended]

    8. Section 141.131 is amended by revising paragraphs (a), (b), 
(d)(2), (d)(3), (d)(4)(i), (d)(4)(ii), and the table in paragraph 
(c)(1), and adding paragraph (d)(6) to read as follows:


Sec.  141.131  Analytical requirements.

    (a) General. (1) Systems must use only the analytical methods 
specified in this section, or their equivalent as approved by EPA, to 
demonstrate compliance with the requirements of this subpart and with 
the requirements of subparts U and V. These methods are effective for 
compliance monitoring February 16, 1999, unless a different effective 
date is specified in this section or by the State.
    (2) The following documents are incorporated by reference. The 
Director of the Federal Register approves this incorporation by 
reference in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies 
may be inspected at EPA's Drinking Water Docket, 1301 Constitution 
Avenue, NW., EPA West, Room B102, Washington, DC 20460, or at the 
Office of the Federal Register, 800 North Capitol Street, NW., Suite 
700, Washington, DC. EPA Method 552.1 is in Methods for the 
Determination of Organic Compounds in Drinking Water-Supplement II, 
USEPA, August 1992, EPA/600/R-92/129 (available through National 
Information Technical Service (NTIS), PB92-207703). EPA Methods 502.2, 
524.2, 551.1, and 552.2 are in Methods for the Determination of Organic 
Compounds in Drinking Water-Supplement III, USEPA, August 1995, EPA/
600/R-95/131. (Available through NTIS, PB95-261616). EPA Method 300.0 
for chlorite and bromide is in Methods for the Determination of 
Inorganic Substances in Environmental Samples, USEPA, August 1993, EPA/
600/R-93/100 (available through NTIS, PB94-121811). EPA Methods 300.1 
for chlorite, bromate, and bromide and 321.8 for bromate are in Methods 
for the Determination of Organic and Inorganic Compounds in Drinking 
Water, Volume 1, USEPA, August 2000, EPA 815-R-00-014 (available 
through NTIS, PB2000-106981). EPA Method 317.0, Revision 2.0, 
``Determination of Inorganic Oxyhalide Disinfection By-Products in 
Drinking Water Using Ion Chromotography with the Addition of a 
Postcolumn Reagent for Trace Bromate Analysis,'' USEPA, July 2001, EPA 
815-B-01-001, EPA Method 326.0, Revision 1.0, ``Determination of 
Inorganic Oxyhalide Disinfection By-Products in Drinking Water Using 
Ion Chromatography Incorporating the Addition of a Suppressor Acidified 
Postcolumn Reagent for Trace Bromate Analysis,'' USEPA, June 2002, EPA 
815-R-03-007, EPA Method 327.0, Revision 1.0, ``Determination of 
Chlorine Dioxide and Chlorite Ion in Drinking Water Using Lissamine 
Green B and Horseradish Peroxidase with Detection by Visible 
Spectrophotometry,'' USEPA, July 2003, and EPA Method 552.3, Revision 
1.0, ``Determination of Haloacetic Acids and Dalapon in Drinking Water 
by Liquid-liquid Extraction, Derivatization, and Gas Chromatography 
with Electron Capture Detection,'' USEPA, July 2003, can be

[[Page 49667]]

accessed and downloaded directly on-line at www.epa.gov/safewater/methods/sourcalt.html. EPA Method 415.3, Revision 1.0, ``Determination 
of Total Organic Carbon and Specific UV Absorbance at 254 nm in Source 
Water and Drinking Water,'' USEPA, June 2003, is available from: 
Chemical Exposure Research Branch, Microbiological & Chemical Exposure 
Assessment Research Division, National Exposure Research Laboratory, 
U.S. Environmental Protection Agency, Cincinnati, OH 45268, Fax Number 
513-569-7757, Phone number: 513-569-7586. Standard Methods 4500-Cl D, 
4500-Cl E, 4500-Cl F, 4500-Cl G, 4500-Cl H, 4500-Cl I, 4500-
ClO2 E, 6251 B, and 5910 B shall be followed in accordance 
with Standard Methods for the Examination of Water and Wastewater, 19th 
or 20th Editions or the On-Line Version, American Public Health 
Association, 1995, 1998, and 2003, respectively. The cited methods 
published in any of these three editions may be used. Standard Method 
4500-ClO2 D shall be followed in accordance with Standard 
Methods for the Examination of Water and Wastewater, 19th or 20th 
Editions, American Public Health Association, 1995 and 1998, 
respectively. Standard Methods 5310 B, 5310 C, and 5310 D shall be 
followed in accordance with the Supplement to the 19th Edition of 
Standard Methods for the Examination of Water and Wastewater, or the 
Standard Methods for the Examination of Water and Wastewater, 20th 
Edition, or the On-Line Version, American Public Health Association, 
1995, 1998, and 2003, respectively. The cited methods published in any 
of these editions may be used. Copies may be obtained from the American 
Public Health Association, 1015 Fifteenth Street, NW., Washington, DC 
20005. ASTM Method D 1253-86 shall be followed in accordance with the 
Annual Book of ASTM Standards, Volume 11.01, American Society for 
Testing and Materials, 1996 or any year containing the cited version of 
the method may be used. ASTM D 6581-00 shall be followed in accordance 
with the Annual Book of ASTM Standards, Volume 11.01, American Society 
for Testing and Materials, 2001 or any year containing the cited 
version of the method may be used; copies may be obtained from the 
American Society for Testing and Materials, 100 Barr Harbor Drive, West 
Conshohoken, PA 19428-2959.
    (b) Disinfection byproducts. (1) Systems must measure disinfection 
byproducts by the methods (as modified by the footnotes) listed in the 
following table:

                        Approved Methods for Disinfection Byproduct Compliance Monitoring
----------------------------------------------------------------------------------------------------------------
   Contaminant and methodology \1\            EPA method            Standard Method \2\        ASTM Method \3\
----------------------------------------------------------------------------------------------------------------
TTHM:
    P&T/GC/ElCD & PID................  502.2 \4\
    P&T/GC/MS........................  524.2
    LLE/GC/ECD.......................  551.1
HAA5:
    LLE (diazomethane)/GC/ECD........                            6251 B \5\...............
    SPE (acidic methanol)/GC/ECD.....  552.1 \5\
    LLE (acidic methanol)/GC/ECD.....  552.2, 552.3.
Bromate:
    Ion chromatography...............  300.1                     .........................  D 6581-00
    Ion chromatography & post column   317.0 Rev 2.0 \6\, 326.0
     reaction.                          \6\
    IC/ICP-MS........................  321.8 \6, 7\
Chlorite:
    Amperometric titration...........                            4500-C1O2 E \8\..........
    Spectrophotometry................  327.0 \8\.                .........................
    Ion chromatography...............  300.0, 300.1, 317.0 Rev.  .........................  D 6581-00
                                        2.0, 326.0
----------------------------------------------------------------------------------------------------------------
\1\ P&T = purge and trap; GC = gas chromatography; ElCD = electrolytic conductivity detector; PID =
  photoionization detector; MS = mass spectrometer; LLE = liquid/liquid extraction; ECD = electron capture
  detector; SPE = solid phase extraction; IC = ion chromatography; ICP-MS = inductively coupled plasma/mass
  spectrometer
\2\ 219th or 20th editions or the On-Line Version of Standard Methods for the Examination of Water and
  Wastewater, 1995, 1998, and 2003, respectively, American Public Health Association; any of these editions may
  be used.
\3\ Annual Book of ASTM Standards, 2001 or any year containing the cited version of the method, Vol 11.01.
\4\ If TTHMs are the only analytes being measured in the sample, then a PID is not required.
\5\ The samples must be extracted within 14 days of sample collection.
\6\ Ion chromatography & post column reaction or IC/ICP-MS must be used for monitoring of bromate for purposes
  of demonstrating eligibility of reduced monitoring, as prescribed in Sec.   141.132(b)(3)(ii).
\7\ Samples must be preserved at the time of sampling with 50 mg ethylenediamine (EDA)/L of sample and must be
  analyzed within 28 days.
\8\ Amperometric titration or spectrophotometry may be used for routine daily monitoring of chlorite at the
  entrance to the distribution system, as prescribed in Sec.   141.132(b)(2)(i)(A). Ion chromatography must be
  used for routine monthly monitoring of chlorite and additional monitoring of chlorite in the distribution
  system, as prescribed in Sec.   141.132(b)(2)(i)(B) and (b)(2)(ii).

    (2) Analysis under this section for disinfection byproducts must be 
conducted by laboratories that have received certification by EPA or 
the State, except as specified under paragraph (b)(3)of this section. 
To receive certification to conduct analyses for the DBP contaminants 
in Sec. Sec.  141.64, 141.135, and subparts U and V of this part, the 
laboratory must:
    (i) Analyze Performance Evaluation (PE) samples that are acceptable 
to EPA or the State at least once during each consecutive 12 month 
period by each method for which the laboratory desires certification.
    (ii) Achieve quantitative results on the PE sample analyses that 
are within the following acceptance limits which become effective [date 
60 days after date of final rule publication] for purposes of 
certification:

[[Page 49668]]



------------------------------------------------------------------------
                                    Acceptance
               DBP                    limits            Comments
                                    (percent)
------------------------------------------------------------------------
TTHM:
    Chloroform...................        +/-20  Laboratory must meet all
    Bromodichloromethane.........        +/-20   4 individual THM
    Dibromochloromethane.........        +/-20   acceptance limits in
    Bromoform....................        +/-20   order to successfully
                                                 pass a PE sample for
                                                 TTHM.
HAA5:
    Monochloroacetic Acid........        +/-40  Laboratory must meet the
    Dichloroacetic Acid..........        +/-40   acceptance limits for 4
    Trichloroacetic Acid.........        +/-40   out of 5 of the HAAS
    Monobromacetic Acid..........        +/-40   compounds in order to
    Dibromoacetic Acid...........        +/-40   successfully pass a PE
                                                 sample for HAA5.
Chlorite.........................        +/-30
Bromate..........................        +/-30
------------------------------------------------------------------------

    (iii) Report quantitative data for concentrations at least as low 
as the ones listed in the following table for all DBP samples analyzed 
for compliance with Sec. Sec.  141.64, 141.135, 141.136, and subparts U 
and V of this part:

------------------------------------------------------------------------
                                        Minimum
                                       reporting
                DBP                  level (ug/L)         Comments
                                          \7\
------------------------------------------------------------------------
TTHM \2\:
    Chloroform....................             1.0
    Bromodichloromethane..........             1.0
    Dibromochloromethane..........             1.0
    Bromoform.....................             1.0
HAA5: \2\
    Monochloroacetic Acid.........             2.0
    Dichloroacetic Acid...........             1.0
    Trichloroacetic Acid..........             1.0
    Monobromoacetic Acid..........             1.0
    Dibromoacetic Acid............             1.0
Chlorite..........................            200.
Bromate...........................      5.0 or 1.0  Laboratories that
                                                     use EPA Methods
                                                     317.0 Revision 2.0,
                                                     326.0 or 321.8 must
                                                     meet a 1.0 [mu]g/L
                                                     MRL for bromate.
------------------------------------------------------------------------
\1\ The calibration curve must encompass the minimum reporting level
  (MRL) concentration and the laboratory must verify the accuracy of the
  calibration curve at the lowest concentration for which quantitative
  data are reported by analyzing a calibration check standard at that
  concentration at the beginning of each batch of samples. The measured
  concentration for the check standard must be within +/-50% of the
  expected value. Data may be reported for concentrations lower than the
  MRL as long as the precision and accuracy criteria are met by
  analyzing a standard at the lowest reporting limit chosen by the
  laboratory.
\2\ When adding the individual trihalomethane or haloacetic acid
  concentrations to calculate the TTHM or HAA5 concentrations,
  respectively, a zero is used for any analytical result that is less
  than the MRL concentration for that DBP.

    (3) A party approved by EPA or the State must measure daily 
chlorite samples at the entrance to the distribution system.
    (c) * * *
    (1) * * *

----------------------------------------------------------------------------------------------------------------
                                                                               Residual Measured \1\
                                   Standard     ASTM       EPA   -----------------------------------------------
          Methodology               method     method    method      Free      Combined      Total     Chlorine
                                                                   chlorine    chlorine    chlorine     dioxide
----------------------------------------------------------------------------------------------------------------
Amperometric Titration.........  4500-Cl D    D 1253-   ........  X           X           X           ..........
                                               86
Low Level Amperometric           4500-Cl E    ........  ........  ..........  ..........  X           ..........
 Titration.
DPD Ferrous Titrimetric........  4500-Cl F    ........  ........  X           X           X
DPD Colorimetric...............  4500-Cl G    ........  ........  X           X           X
Syringaldazine (FACTS).........  4500-Cl      ........  ........  X           ..........  ..........  ..........
Iodometric Electrode...........  4500-Cl      ........  ........  ..........  ..........  X           ..........
DPD............................  4500-ClO2    ........  ........  ..........  ..........  ..........  X
Amperometric Method II.........  4500-ClO2 E  ........  ........  ..........  ..........  ..........  X
Lissamine Green                  ...........  ........  327.0     ..........  ..........  ..........  X
 Spectrophotometric.
----------------------------------------------------------------------------------------------------------------
\1\ X indicates method is approved for measuring specified disinfectant residual. Free chlorine or total
  chlorine may be measured for demonstrating compliance with the chlorine MRDL and combined chlorine or total
  chlorine may be measured for demonstrating compliance with the chloramine MRDL.


[[Page 49669]]

* * * * *
    (d) * * *
    (2) Bromide. EPA Methods 300.0, 300.1, 317.0 Revision 2.0, 326.0, 
or ASTM D 6581-00.
    (3) Total Organic Carbon (TOC). Standard Method 5310 B (High-
Temperature Combustion Method) or Standard Method 5310 C (Persulfate-
Ultraviolet or Heated-Persulfate Oxidation Method) or Standard Method 
5310 D (Wet-Oxidation Method) or EPA Method 415.3. Inorganic carbon 
must be removed from the samples prior to analysis. TOC samples may not 
be filtered prior to analysis. TOC samples must be acidified at the 
time of sample collection to achieve pH less than or equal to 2 with 
minimal addition of the acid specified in the method or by the 
instrument manufacturer. Acidified TOC samples must be analyzed within 
28 days.
    (4) * * *
    (i) Dissolved Organic Carbon (DOC). Standard Method 5310 B (High-
Temperature Combustion Method) or Standard Method 5310 C (Persulfate-
Ultraviolet or Heated-Persulfate Oxidation Method) or Standard Method 
5310 D (Wet-Oxidation Method) or EPA Method 415.3. DOC samples must be 
filtered through the 0.45 [mu]m pore-diameter filter as soon as 
practical after sampling, not to exceed 48 hours. After filtration, DOC 
samples must be acidified to achieve pH less than or equal to 2 with 
minimal addition of the acid specified in the method or by the 
instrument manufacturer. Acidified DOC samples must be analyzed within 
28 days. Inorganic carbon must be removed from the samples prior to 
analysis. Water passed through the filter prior to filtration of the 
sample must serve as the filtered blank. This filtered blank must be 
analyzed using procedures identical to those used for analysis of the 
samples and must meet the following criteria: DOC < 0.5 mg/L.
    (ii) Ultraviolet Absorption at 254 nm (UV254). Standard 
Method 5910 B (Ultraviolet Absorption Method) or EPA Method 415.3. UV 
absorption must be measured at 253.7 nm (may be rounded off to 254 nm). 
Prior to analysis, UV254 samples must be filtered through a 
0.45 [mu]m pore-diameter filter. The pH of UV254 samples may 
not be adjusted. Samples must be analyzed as soon as practical after 
sampling, not to exceed 48 hours.
* * * * *
    (6) Magnesium. All methods allowed in Sec.  141.23(k)(1) for 
measuring magnesium.
    9. Section 141.132 is amended by revising paragraphs (b)(3)(ii) and 
(e) to read as follows:


Sec.  141.132  Monitoring requirements.

* * * * *
    (b) * * *
    (i) * * *
    (ii) Reduced monitoring.
    (A) Until [date three years from final rule publication], systems 
required to analyze for bromate may reduce monitoring from monthly to 
quarterly, if the system's average source water bromide concentration 
is less than 0.05 mg/L based on representative monthly bromide 
measurements for one year. The system may remain on reduced bromate 
monitoring until the running annual average source water bromide 
concentration, computed quarterly, is equal to or greater than 0.05 mg/
L based on representative monthly measurements. If the running annual 
average source water bromide concentration is =0.05 mg/L, 
the system must resume routine monitoring required by paragraph 
(b)(3)(i) of this section.
    (B) Beginning [date three years from final rule publication], 
systems may no longer use the provisions of paragraph (b)(3)(ii)(A) of 
this section to qualify for reduced monitoring. A system required to 
analyze for bromate may reduce monitoring from monthly to quarterly, if 
the system's running annual average bromate concentration is less than 
0.0025 mg/L based on monthly bromate measurements under paragraph 
(b)(3)(i) of this section for the most recent four quarters, with 
samples analyzed using Method 317.0 Revision 2.0, 325.0 or 321.8. If a 
system has qualified for reduced bromate monitoring under paragraph 
(b)(3)(ii)(A) of this section, that system may remain on reduced 
monitoring as long as the running annual average of quarterly bromate 
samples does not exceed 0.0025 mg/L based on samples analyzed using 
Method 317.0 Revision 2.0, 325.0, or 321.8. If the running annual 
average bromate concentration is 0.0025 mg/L, the system 
must resume routine monitoring required by paragraph (b)(3)(i) of this 
section.
* * * * *
    (e) Monitoring requirements for source water TOC. In order to 
qualify for reduced monitoring for TTHM and HAA5 under paragraph 
(b)(1)(ii) of this section, subpart H systems not monitoring under the 
provisions of paragraph (d) of this section must take monthly TOC 
samples approximately every 30 days at a location prior to any 
treatment. In addition to meeting other criteria for reduced monitoring 
in paragraph (b)(1)(ii) of this section, the source water TOC running 
annual average must be <=4.0 mg/L (based on the most recent four 
quarters of monitoring) on a continuing basis at each treatment plant 
to reduce or remain on reduced monitoring for TTHM and HAA5.
* * * * *
    10. Section 141.134 is amended by revising paragraph (b) 
introductory text to read as follows:


Sec.  141.134  Reporting and recordkeeping requirements.

* * * * *
    (b) Disinfection byproducts. In addition to reporting required 
under Sec.  141.136(e), systems must report the information specified 
in the following table:
* * * * *
    11. Section 141.135 is amended by revising paragraph (a)(3)(ii) to 
read as follows:


Sec.  141.135  Treatment technique for control of disinfection 
byproduct (DBP) precursors.

    (a) * * *
    (3) * * *
    (ii) Softening that results in removing at least 10 mg/L of 
magnesium hardness (as CaCO3), measured monthly according to 
Sec.  141.131(d)(6) and calculated quarterly as a running annual 
average.
* * * * *
    12. Section 141.136 is added to subpart L to read as follows:


Sec.  141.136  Additional compliance requirements for Stage 2A.

    (a) Applicability. Any system that takes TTHM and HAA5 compliance 
samples under this subpart at more than one location in its 
distribution system is subject to additional MCL requirements beginning 
[date 3 years after publication of final rule] until the dates 
identified for compliance with subpart V in Sec.  141.620(c). Any 
system that takes samples at more than one location must calculate a 
locational running annual average (LRAA) for each sampling point and 
comply with the MCLs of 0.120 mg/L for TTHM and 0.100 mg/L for HAA5 
listed in Sec.  141.64(b)(2), except as provided for under paragraph 
(c) of this section.
    (b) Compliance. (1) Systems must calculate a locational running 
annual average each quarter for each monitoring location at which they 
took TTHM and HAA5 samples under their monitoring plan developed under 
Sec.  141.132(f) by averaging the results of TTHM or HAA5 monitoring at 
that sample location during the four most recent quarters.
    (2) Systems required to conduct quarterly monitoring under this 
subpart must begin to make compliance calculations under paragraph (b) 
of this

[[Page 49670]]

section at the end of the fourth calendar quarter that follows the 
compliance date in paragraph (a) of this section and at the end of each 
subsequent quarter. Systems required to conduct monitoring at a 
frequency that is less than quarterly under this subpart must make 
compliance calculations under paragraph (b) of this section beginning 
with the first compliance sample taken after the compliance date in 
paragraph (a) of this section.
    (3) Failure to monitor will be treated as a monitoring violation 
for each quarter that a monitoring result would be used in a locational 
running annual average compliance calculation.
    (c) Consecutive systems. A consecutive system must comply with the 
TTHM and HAA5 MCLs in Sec.  141.64(b)(2) at each monitoring location in 
its distribution system identified in its monitoring plan developed 
under Sec.  141.132(f).
    (d) Reporting. Systems must submit the compliance calculations and 
locational running annual averages under this section as part of the 
reports required under Sec.  141.134.

Subpart O--[Amended]

    13. Section 141.151 is amended by revising paragraph (d) to read as 
follows:


Sec.  141.151  Purpose and applicability of this subpart.

* * * * *
    (d) For the purpose of this subpart, detected means: At or above 
the levels prescribed by Sec.  141.23(a)(4) for inorganic contaminants, 
at or above the levels prescribed by Sec.  141.24(f)(7) for the 
contaminants listed in Sec.  141.61(a), at or above the levels 
prescribed by Sec.  141.24(h)(18) for the contaminants listed in Sec.  
141.61(c), at or above the levels prescribed by Sec.  
141.131(b)(2)(iii) for the contaminants or contaminant groups listed in 
Sec.  141.64 and Sec.  141.153(d)(iv), and at or above the levels 
prescribed by Sec.  141.25(c) for radioactive contaminants.
* * * * *
    14. Section 141.153 is amended by revising paragraphs (d)(4)(iv)(B) 
and (d)(4)(iv)(C) to read as follows:


Sec.  141.153  Content of the reports.

* * * * *
    (d) * * *
    (4) * * *
    (iv) * * *
    (B) When compliance with the MCL is determined by calculating a 
running annual average of all samples taken at a sampling point: the 
highest average of any of the sampling points and the range of all 
sampling points expressed in the same units as the MCL. For the MCLs 
for TTHM and HAA5 in Sec.  141.64(b)(2) and (3), systems must include 
the highest locational running annual average for TTHM and HAA5 and the 
range of individual sample results for all sampling points expressed in 
the same units as the MCL. If more than one site exceeds the MCL, the 
system must include the locational running annual averages for all 
sites that exceed the MCL.
    (C) When compliance with the MCL is determined on a system-wide 
basis by calculating a running annual average of all samples at all 
sampling points: the average and range of detection expressed in the 
same units as the MCL. The system is not required to include the range 
of individual sample results for the IDSE conducted under subpart U of 
this part.
* * * * *

Subpart Q--[Amended]

    15. In Appendix A, the table is amended by revising entries 1.G.1 
and 1.G.2, and endnotes 12 and 20, to read as follows:

     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                          Tier of
                                         public         Citation          public
                                         notice                           notice              Citation
                                        required                         required
----------------------------------------------------------------------------------------------------------------
I. Violations of National Primary
 Drinking Water Regulations
 (NPDWR):\3\
 
                                                  * * * * * * *
G. Disinfection Byproducts, * * *
1. Total trihalomethanes (TTHM).....            2  141.12\12\,                   3  141.30\12\,
                                                   141.64(b)\20\                    141.132(a)-(b)\20\,
                                                                                    141.620-.630
2. Haloacetic acids (HAA5)..........            2  141.64(b)\20\                 3  141.132(a)-(b)\20\,
                                                                                    141.620-.630
----------------------------------------------------------------------------------------------------------------

* * * * *

Appendix A--Endnotes

    12. Sec. Sec.  141.12 and 141.30 will no longer apply after 
December 31, 2003.
* * * * *
    20. Sec. Sec.  141.64(b)(1) and 141.132(a)-(b) apply until 
Sec. Sec.  141.64(b)(3) and 141.620-.630 take effect under the 
schedule in Sec.  141.620(c). Sec.  141.64(b)(2) takes effect on 
[date three years following final rule publication] and remains in 
effect until the effective dates for subpart V of this part 
compliance in the table in Sec.  141.620(c).
* * * * *
    16. In Appendix B the table is amended by revising entries H.79, 
H.80, and endnote 17, and adding endnote 23, to read as follows:

[[Page 49671]]



  Appendix B to Subpart Q of Part 141--Standard Health Effects Language
                         for Public Notification
------------------------------------------------------------------------
                                                              Standard
                                                               health
                                 MCLG\1\                      effects
          Contaminant              mg/L      MCL\2\ mg/L    language for
                                                               public
                                                            notification
------------------------------------------------------------------------
 
                              * * * * * * *
H. Disinfection Byproducts
 (DBPs), * * * \17\:
79. Total trihalomethanes       N/A        0.10/0.120/     * * *
 (TTHLM).                                   0.080 18, 19,
                                            23
80. Haloacetic acids (HAA5)...  N/A        0.060/0.10020,  * * *
                                            23
------------------------------------------------------------------------

* * * * *

Appendix B--Endnotes

* * * * *
    17. Surface water systems and ground water systems under the 
direct influence of surface water are regulated under subpart H of 
40 CFR 141. Subpart H community and non-transient non-community 
systems serving =10,000 must comply with subpart L DBP 
MCLs and disinfectant maximum residual disinfectant levels (MRDLs) 
beginning January 1, 2002. All other community and non-transient 
non-community systems must comply with subpart L DBP MCLs and 
disinfectant MRDLs beginning January 1, 2004. Subpart H transient 
non-community systems serving =10,000 that use chlorine 
dioxide as a disinfectant or oxidant must comply with the chlorine 
dioxide MRDL beginning January 1, 2002. All other transient non-
community systems that use chlorine dioxide as a disinfectant or 
oxidant must comply with the chlorine dioxide MRDL beginning January 
1, 2004.
* * * * *
    23. Community and non-transient non-community systems must 
comply with TTHM and HAA5 MCLs of 0.120 mg/L and 0.100 mg/L, 
respectively (with compliance calculated as a locational running 
annual average) beginning [date three years following publication of 
final rule] until they are required to comply with subpart V TTHM 
and HAA5 MCLs of 0.080 mg/L and 0.060 mg/L, respectively (with 
compliance calculated as a locational running annual average). 
Community and non-transient non-community systems serving 
=10,000 must comply with subpart V TTHM and HAA5 MCLs 
(with compliance calculated as a locational running annual average) 
beginning [date six years following publication of final rule]. 
Community and non-transient non-community systems serving <10,000 
must comply with subpart V TTHM and HAA5 MCLs (with compliance 
calculated as a locational running annual average) beginning [date 
90 months following publication of final rule].
* * * * *
    17. Part 141 is amended by adding new subpart U to read as follows:
Subpart U--Initial Distribution System Evaluations
Sec.
141.600 General requirements.
141.601 Initial Distribution System Evaluation (IDSE) requirements.
141.602 IDSE monitoring.
141.603 Alternatives other than IDSE monitoring.
141.604 IDSE reports.
141.605 Subpart V monitoring location recommendations to the State.

Subpart U--Initial Distribution System Evaluations


Sec.  141.600  General requirements.

    (a) The requirements of subpart U constitute national primary 
drinking water regulations. The regulations in this subpart establish 
monitoring and other requirements for identifying compliance monitoring 
locations to be used for determining compliance with maximum 
contaminant levels for total trihalomethanes (TTHM) and haloacetic 
acids (five)(HAA5) in subpart V through the use of an Initial 
Distribution System Evaluation (IDSE). IDSEs are studies, used in 
conjunction with subpart L compliance monitoring, to identify and 
select subpart V compliance monitoring sites that represent high TTHM 
and HAA5 levels throughout the distribution system. The studies will be 
based on system-specific monitoring as provided in Sec.  141.602. As an 
alternative, you may use other system-specific data that provide 
equivalent or better information on site selection for monitoring under 
subpart V as provided for in Sec.  141.603(a).
    (b) Applicability. You are subject to these requirements if your 
system is a community water system that adds a primary or residual 
disinfectant other than ultraviolet light or delivers water that has 
been treated with a primary or residual disinfectant other than 
ultraviolet light or if your system is a nontransient noncommunity 
water system that serves at least 10,000 people and adds a primary or 
residual disinfectant other than ultraviolet light or delivers water 
that has been treated with a primary or residual disinfectant other 
than ultraviolet light. You must conduct an Initial Distribution System 
Evaluation (IDSE), unless you meet the 40/30 certification criteria in 
Sec.  141.603(b) or the State has granted a very small system waiver 
for the IDSE or you meet the criteria defined by the State for a very 
small system waiver under Sec.  141.603(c). If you have a very small 
system waiver for the IDSE under Sec.  141.603(c), you are not required 
to submit an IDSE report. All other systems must submit an IDSE report, 
even if you meet the 40/30 certification criteria in Sec.  141.603(c).
    (c) Schedule. You must comply with the Initial Distribution System 
Evaluation (IDSE) on the schedule in the following table, based on your 
system type.

------------------------------------------------------------------------
                                            You must submit your IDSE
     If you are this type of system         report to the state by \1\
------------------------------------------------------------------------
(1) Subpart H serving =10,000.                              publication of final rule]
(2) Subpart H serving <10,000..........  [date 24 mos. following
                                          publication of final rule] \2\
(3) Ground water serving =10,000.                              publication of final rule]
(4) Ground water serving <10,000.......  [date 24 mos. following
                                          publication of final rule] \2\
(5) Consecutive system.................  at the same time as the system
                                          with the earliest compliance
                                          date in the combined
                                          distribution system \3\
------------------------------------------------------------------------
\1\ Systems that meet the 40/30 certification criteria in Sec.
  141.603(b) are encouraged to submit their IDSE report as soon as the
  certification criteria are met.
\2\ You must comply by [date 24 mos. following publication of final
  rule] if you are a wholesale system and any system in the combined
  distribution system serves at least 10,000 people. You must comply by
  [date 48 mos. following publication of final rule] if no system in the
  combined distribution system serves at least 10,000 people.

[[Page 49672]]

 
\3\ You must comply by [date 24 mos. following publication of final
  rule] if any system in the combined distribution system serves at
  least 10,000 people. You must comply by [date 48 mos. following
  publication of final rule] if no system in the combined distribution
  system serves at least 10,000 people.

    (d) Violations. You must comply with specific monitoring and 
reporting requirements. You must prepare for, conduct, analyze, and 
submit your IDSE report no later than the date specified in Sec.  
141.600(c). Failure to conduct a required IDSE or to submit a required 
IDSE report by the date specified in paragraph (c) of this section is a 
monitoring violation. If you do not submit your IDSE report to your 
State, or if you submit the report after the specified date, you must 
comply with any additional State-specified requirements, which may 
include conducting another IDSE.


Sec.  141.601  Initial Distribution System Evaluation (IDSE) 
requirements.

    (a) You must conduct an IDSE that meets the requirements in Sec.  
141.602 or Sec.  141.603(a) or meet the 40/30 certification criteria in 
Sec.  141.603(b) or have received a very small system waiver for the 
IDSE from the State under Sec.  141.603(c). If you do not take the full 
complement of TTHM and HAA5 compliance samples required of a system 
with your population and source water under subpart L, but are required 
to conduct an IDSE under this subpart, you are not eligible for either 
the 40/30 certification in Sec.  141.603(b) or the very small system 
waiver in Sec.  141.603(c) and must conduct an IDSE that meets the 
requirements in Sec.  141.602 or Sec.  141.603(a).
    (b) You may use any alternative listed in the table below for which 
you qualify.

                                                IDSE Alternatives
----------------------------------------------------------------------------------------------------------------
               Alternatives                        Eligibility                    Regulatory reference
----------------------------------------------------------------------------------------------------------------
(1) Monitoring...........................  All systems required to      Sec.   141.602
                                            conduct an IDSE.
(2) System-specific study................  All systems required to      Sec.   141.603(a)
                                            conduct an IDSE.
(3) 40/30 certification..................  Any system with all TTHM     Sec.   141.603(b)
                                            compliance samples <=0.040
                                            mg/L and all HAA5
                                            compliance samples <=0.030
                                            mg/L during the period
                                            specified in Sec.
                                            141.603(b).
(4) Very small system waiver.............  Any system serving <500 for  Sec.   141.603(c)
                                            which the State has
                                            granted a waiver.
----------------------------------------------------------------------------------------------------------------

    (c) IDSE results will not be used for the purpose of determining 
compliance with MCLs in Sec.  141.64.
    (d) Additional provisions:
    (1) You may consider multiple wells drawing water from a single 
aquifer as one treatment plant for determining the minimum number of 
TTHM and HAA5 samples required, with State approval in accordance with 
criteria developed under Sec.  142.16(h)(5) of this chapter. State 
approvals made under Sec.  141.132(a)(2) to treat multiple wells 
drawing water from a single aquifer as one treatment plant remain in 
effect unless withdrawn by the State.
    (2) If you are a consecutive system, you must comply with the IDSE 
requirements in this subpart based on whether you buy some or all of 
your water from another PWS during 2004 for systems with an IDSE report 
due [date 24 months after publication of final rule] or during 2006 for 
systems with an IDSE report due [date 48 months after publication of 
final rule]. A consecutive system that buys some, but not all, of its 
finished water during the period identified in this paragraph must 
treat each consecutive system entry point from a wholesale system as a 
treatment plant for the consecutive system for the purpose of 
determining monitoring requirements of this subpart if water is 
delivered from the wholesale system to the consecutive system for at 
least 60 consecutive days through any of the consecutive system entry 
points. A consecutive system that buys all its finished water during 
the period identified in this paragraph must monitor based on 
population and source water for the purpose of determining monitoring 
requirements of this subpart.
    (i) You may request that the State allow multiple consecutive 
system entry points from a single wholesale system to a single 
consecutive system to be considered one treatment plant.
    (ii) In the request to the State for approval of multiple 
consecutive system entry points to be considered one treatment plant, 
you must demonstrate that factors such as relative locations of entry 
points, detention times, sources, and the presence of treatment (such 
as corrosion control or booster disinfection) will have a minimal 
differential effect on TTHM and HAA5 formation associated with 
individual entry points.


Sec.  141.602  IDSE monitoring.

    (a) You must conduct IDSE monitoring for each treatment plant as 
indicated in the table in this paragraph. You must collect dual sample 
sets at each monitoring location. One sample in the set must be 
analyzed for TTHM. The other sample in the set must be analyzed for 
HAA5. If approved by the State under the provisions of Sec.  
141.601(d)(1), you may consider multiple wells drawing water from the 
same aquifer to be one treatment plant for the purpose of determining 
monitoring requirements. You must conduct one monitoring period during 
the peak historical month for TTHM levels or HAA5 levels or the month 
of warmest water temperature. You must review available compliance, 
study, or operational data to determine the peak historical month for 
TTHM or HAA5 levels or warmest water temperature.

[[Page 49673]]



------------------------------------------------------------------------
                                                     At these locations
If you are this type of system    Then you must      for each treatment
                                     monitor           plant \1\,\2\
------------------------------------------------------------------------
(1) Subpart H serving =10,000.                     every 60 days      sets per monitoring
                                 for one year       period at locations
                                 (six monitoring    other than subpart L
                                 periods).          TTHM/HAA5 monitoring
                                                    locations based on
                                                    conditions:
                                                   If CHLORINE is used
                                                    as residual
                                                    disinfectant: one
                                                    near distribution
                                                    system entry point,
                                                    two at average
                                                    residence time, five
                                                    at points
                                                    representative of
                                                    highest expected
                                                    TTHM (three sites)
                                                    and HAA5
                                                    concentration (two
                                                    sites).
                                                   If CHLORAMINE is used
                                                    as residual
                                                    disinfectant for any
                                                    part of the year:
                                                    two near
                                                    distribution system
                                                    entry point, two at
                                                    average residence
                                                    time, four at points
                                                    representative of
                                                    highest expected
                                                    TTHM (two sites) and
                                                    HAA5 concentration
                                                    (two sites).
(2) Subpart H serving 500-      Approximately      Two dual sample sets
 9,999.                          every 90 days      per monitoring
                                 for one year       period at locations
                                 (four monitoring   other than the for
                                 periods).          one year subpart L
                                                    TTHM/HAA5 monitoring
                                                    location; one each
                                                    representative of
                                                    expected high
                                                    periods) TTHM level
                                                    and HAA5 level.
(3) Subpart H serving <500....  Approximately      Two dual sample sets
                                 every 180 days     per monitoring
                                 for one year       period at locations
                                 (two monitoring    other than the
                                 periods).          subpart L TTHM/HAA5
                                                    monitoring location;
                                                    one each
                                                    representative of
                                                    expected high
                                                    periods) TTHM level
                                                    and HAA5 level.
(4) Ground water serving =10,000.                 every 90 days      per monitoring
                                 for one year       period at locations
                                 (four monitoring   other than the
                                 periods).          subpart L TTHM/HAA5
                                                    monitoring location;
                                                    one each
                                                    representative of
                                                    expected high
                                                    periods) TTHM level
                                                    and HAA5 level.
(5) Ground water serving <      Approximately      Two dual sample sets
 10,000.                         every 180 days     per monitoring
                                 for one year       period at locations
                                 (two monitoring    other than the
                                 periods).          subpart L TTHM/HAA5
                                                    monitoring location;
                                                    one each
                                                    representative of
                                                    expected high
                                                    periods) TTHM level
                                                    and HAA5 level.
(6) Consecutive system........  At a frequency     --For a consecutive
                                 based on source    system that buys all
                                 water and your     its finished water,
                                 population \3\.    number of samples
                                                    and locations as
                                                    specified in
                                                    paragraph (b) of
                                                    this section.
                                                   --For a consecutive
                                                    system that buys
                                                    some, but not all,
                                                    of its finished
                                                    water, serves =10,000, and
                                                    receives water from
                                                    a subpart H system:
                                                    at IDSE locations
                                                    required of a
                                                    subpart H system
                                                    serving =10,000.
                                                   --For a consecutive
                                                    system that does not
                                                    meet any other
                                                    criteria in this
                                                    paragraph: two dual
                                                    sample sets per
                                                    monitoring period at
                                                    locations other than
                                                    the subpart L TTHM/
                                                    HAA5 compliance
                                                    monitoring location;
                                                    one each
                                                    representative of
                                                    expected high TTHM
                                                    levels and HAA5
                                                    levels.
------------------------------------------------------------------------
\1\ Including treatment plants for consecutive system entry points that
  operate for at least 60 consecutive days.
\2\ The State may require additional monitoring.
\3\ You must monitor at the frequency required of a subpart H system
  with your population if you deliver any water required to be treated
  under subpart H. You must monitor at the frequency required of a
  ground water system with your population if you deliver no water
  required to be treated under subpart H.

    (b) IDSE monitoring for consecutive systems that buy all their 
water.

                   IDSE Monitoring Locations for Consecutive Systems that Buy All Their Water
----------------------------------------------------------------------------------------------------------------
                                                    Number of     Distribution system dual sample set locations
                                                   dual sample                         \1\
                                                       set     -------------------------------------------------
               Population category                  locations
                                                       per       Near entry    Average     Highest     Highest
                                                    monitoring   points \2\   residence      TTHM        HAA5
                                                      period                     time     locations   locations
----------------------------------------------------------------------------------------------------------------
                             Subpart H Consecutive Systems that buy all their water
----------------------------------------------------------------------------------------------------------------
<500 \3\.........................................            2                                1                1
500 to 4,999 \4\.................................            2                                1                1
5,000 to 9,999 \4\...............................            4                         1      2                1
10,000 to 24,999 \5\.............................            8            1            2      3                2
25,000 to 49,999 \5\.............................           12            2            3      4                3
50,000 to 99,999 \5\.............................           16            3            4      5                4
100,000 to 499,999 \5\...........................           24            4            6      8                6
500,000 to 1,499,999 \5\.........................           32            6            8     10                8
1,500,000 to 4,999,999 \5\.......................           40            8           10     12               10
=5,000,000 \5\........................           48           10           12     14               12
--------------------------------------------------

[[Page 49674]]

 
                            Ground Water Consecutive Systems that buy all their water
----------------------------------------------------------------------------------------------------------------
<500 \3\.........................................            2  ...........  ...........      1                1
500 to 9,999 \4\.................................            2  ...........  ...........      1                1
10,000 to 99,999 \4\.............................            6            1            1      2                2
100,000 to 499,999 \4\...........................            8            1            1      3                3
=500,000 \4\..........................           12            2            2      4               4
----------------------------------------------------------------------------------------------------------------
\1\ Sampling locations to be distributed through distribution system. You may not use subpart L compliance
  monitoring locations as IDSE sample sites. You must collect a dual sample set at each sample location.
\2\ If the actual number of entry points to the distribution system is fewer than the specified number of ``near
  entry point'' sampling sites, take additional samples equally at highest TTHM and HAA5 locations. If there is
  an odd extra location number, take the odd sample at highest TTHM location. If the actual number of entry
  points to the distribution system is more than the specified number of sampling locations, take samples first
  at subpart H entry points to the distribution system having the highest water flows and then at ground water
  entry points to the distribution system having the highest water flows.
\3\ You must conduct monitoring during two monitoring periods approximately 180 days apart.
\4\ You must conduct monitoring during four monitoring periods approximately 90 days apart.
\5\ You must conduct monitoring during six monitoring periods approximately 60 days apart.

    (c) You must prepare an IDSE monitoring plan prior to starting IDSE 
monitoring and implement that plan. In the plan, you must identify 
specific monitoring locations and dates that meet the criteria in 
paragraphs (a) and (b) of this section, as applicable.


Sec.  141.603  Alternatives other than IDSE monitoring.

    In lieu of IDSE monitoring under Sec.  141.602, you may use one of 
the alternatives identified in paragraphs (a) through (c) of this 
section for which you qualify to comply with this subpart.
    (a) System-specific study. You may perform an IDSE study based on 
system-specific monitoring or system-specific data if such a study 
identifies equivalent or superior monitoring sites representing high 
TTHM and HAA5 levels as would be identified by IDSE monitoring under 
Sec.  141.602. You must submit an IDSE report that complies with Sec.  
141.604.
    (b) 40/30 certification. In order to qualify for the 40/30 
certification, you must not have had any TTHM or HAA5 monitoring 
violations during the periods specified in paragraphs (b)(1) through 
(b)(3) of this section.
    (1) You are not required to comply with Sec.  141.602 or paragraph 
(a) of this section if you certify to your State that all compliance 
samples under subpart L in 2002 and 2003 (for subpart H systems serving 
=10,000 people) or in 2004 and 2005 (for systems serving 
<10,000 people that are not required to submit an IDSE report by [date 
24 months following publication of final rule]) were <=0.040 mg/L for 
TTHM and <=0.030 mg/L for HAA5.
    (2) If you are a ground water system serving =10,000 
people, you are not required to comply with Sec.  141.602 or paragraph 
(a) of this section if you certify to your State that all TTHM samples 
taken under Sec.  141.30 in 2003 are <=0.040 mg/L and that all TTHM and 
HAA5 compliance samples taken under subpart L during 2004 are <=0.040 
mg/L and <=0.030 mg/L, respectively.
    (3) If you are a consecutive system serving <10,000 required to 
submit an IDSE report by [date 24 months following publication of final 
rule], you are not required to comply with Sec.  141.602 or paragraph 
(a) of this section if you certify to your State that all TTHM and HAA5 
compliance samples taken under subpart L during 2004 are <=0.040 mg/L 
and <=0.030 mg/L, respectively.
    (4) You must submit an IDSE report that complies with Sec.  141.604 
and contains the required certification.
    (c) Very small system waiver. If you serve fewer than 500 people, 
the State may waive IDSE monitoring if the State determines that the 
TTHM and HAA5 monitoring site for each plant under Sec.  141.132 is 
sufficient to represent both the highest TTHM and the highest HAA5 
concentration in your distribution system. If your IDSE monitoring is 
waived, you are not required to submit an IDSE report. You must monitor 
under subpart V during the same month and at the same location as used 
for compliance sampling in subpart L.


Sec.  141.604  IDSE reports.

    You must submit your IDSE report to the State according to the 
schedule in Sec.  141.600(c).
    (a) If you complied by meeting the provisions of Sec. Sec.  141.602 
or 141.603(a), your IDSE report must include the elements required in 
paragraphs (a)(1) through (a)(3) of this section.
    (1) Your report must include all TTHM and HAA5 analytical results 
from subpart L compliance monitoring conducted during the period of the 
IDSE presented in a tabular or spreadsheet format acceptable to the 
State. Your report must also include a schematic of your distribution 
system, with results, location, and date of all IDSE monitoring, 
system-specific study monitoring, and subpart L compliance samples 
noted.
    (2) If you conducted IDSE monitoring under Sec.  141.602, your 
report must include all IDSE TTHM and HAA5 analytical results presented 
in a tabular or spreadsheet format acceptable to the State. Your report 
must also include all additional data you relied on to justify IDSE 
monitoring site selection, plus your original monitoring plan developed 
under Sec.  141.602(c) and an explanation of any deviations from that 
plan.
    (3) If you used the system-specific study alternative in Sec.  
141.603(a), your report must include the basis (studies, reports, data, 
analytical results, modeling) by which you determined that the 
recommended subpart V monitoring sites representing high TTHM and HAA5 
levels are comparable or superior to those that would otherwise have 
been identified by IDSE

[[Page 49675]]

monitoring under Sec.  141.602. Your report must also include an 
analysis that demonstrates that your system-specific study 
characterized expected TTHM and HAA5 levels throughout your entire 
distribution system.
    (b) If you meet the 40/30 certification criteria in Sec.  
141.603(b), your IDSE report must include all TTHM and HAA5 analytical 
results from compliance monitoring used to qualify for the 40/30 
certification and a schematic of your distribution system (with 
results, location, and date of all compliance samples noted). You must 
also include results of those compliance samples taken after the period 
used to qualify for the 40/30 certification for State review.
    (c) Your IDSE report must include your recommendations and 
justification for where and during what month(s) TTHM and HAA5 
monitoring for Subpart V should be conducted. You must base your 
recommendations on the criteria in Sec.  141.605. Your IDSE report must 
also include the population served; system type (subpart H or ground 
water); whether your system is a consecutive system; and, if you 
conducted plant-based monitoring, the number of treatment plants and 
consecutive system entry points.
    (d) Recordkeeping. You must retain a complete copy of your IDSE 
report submitted under Sec.  141.604 for 10 years after the date that 
you submitted your IDSE report. If the State modifies the monitoring 
requirements that you recommended in your IDSE report or if the State 
approves alternative monitoring sites, you must keep a copy of the 
State's notification on file for 10 years after the date of the State's 
notification. You must make the IDSE report and any State notification 
available for review by the State or the public.


Sec.  141.605  Subpart V monitoring location recommendations to the 
State.

    (a) Subpart H systems serving at least 10,000 people. If you are a 
system required to take four dual sample sets per treatment plant per 
quarter under routine monitoring under Sec.  141.621, you must base 
your recommendations on the locations in the distribution system where 
you expect to find the highest TTHM and HAA5 LRAAs. In determining the 
highest LRAA, you must evaluate both subpart L compliance data and IDSE 
data. For each plant, you must recommend locations with:
    (1) The two highest TTHM locational running annual averages;
    (2) The highest HAA5 locational running annual average; and
    (3) An existing subpart L compliance monitoring location identified 
in the Sec.  141.132(f) monitoring plan that is the location of either 
the highest TTHM or HAA5 LRAA among the three compliance monitoring 
locations representative of average residence time (by calculating an 
LRAA for each compliance monitoring location using the compliance 
monitoring results collected during the period of the IDSE).
    (4) You may recommend locations other than those in paragraphs 
(a)(1) through (3) of this section if you include a rationale for 
selecting other locations. If the State approves, you must monitor at 
these locations to determine compliance under subpart V.
    (5) If any of the criteria in this paragraph (a) of this section 
would cause fewer than four locations per treatment plant to be 
recommended, you must identify an additional location(s) with the next 
highest HAA5 LRAA.
    (b) All groundwater systems and subpart H systems serving fewer 
than 10,000 people. If you are a system required to take two dual 
sample sets per treatment plant per quarter or per year or one TTHM and 
one HAA5 sample per plant per year for routine monitoring under Sec.  
141.621, you must select the locations with the highest TTHM locational 
running annual average and highest HAA5 locational running annual 
average, unless you include a rationale for selecting other locations. 
If the State approves, you must monitor at these other locations to 
determine compliance under subpart V. If any of the criteria in this 
paragraph would cause only one location per treatment plant to be 
recommended, you must identify an additional location with the next 
highest HAA5 LRAA or request that you be allowed to monitor only at 
that location.
    (c) Systems that qualify for the 40/30 certification. If you use 
the 40/30 certification in Sec.  141.603(b), you may use either subpart 
L compliance monitoring locations or you may identify monitoring 
locations for Subpart V that are different from those for subpart L. 
You must include a rationale for changing existing subpart L locations, 
choosing locations with a long residence time and a detectable 
residual. If you choose monitoring locations other than those in 
subpart L as subpart V compliance monitoring locations, you must retain 
the subpart L locations with the highest TTHM and HAA5 LRAAs. If any of 
the criteria in this paragraph would cause only one location per 
treatment plant to be recommended, you must identify an additional 
location with the next highest HAA5 LRAA or request that you be allowed 
to monitor only at that location. If you are required to monitor at 
more locations under subpart V of this part than under subpart L of 
this part, you must identify additional locations with a long residence 
time and a detectable residual.
    (d) Consecutive systems that buy some, but not all, of their 
finished water. Your recommendations must comply with Sec. Sec.  
141.601(d) and 141.605 (a) through (c).
    (e) Consecutive systems that buy all their finished water.
    (1) You must select the number of monitoring locations specified in 
the following tables.

   Subpart V.--Sample Frequency for TTHM/HAA5 (as Dual Sample Sets) for Consecutive Systems That Buy All Their
                                                      Water
----------------------------------------------------------------------------------------------------------------
                     Population                                            Number of samples
----------------------------------------------------------------------------------------------------------------
                             Subpart H Consecutive Systems That Buy All Their Water
----------------------------------------------------------------------------------------------------------------
<500................................................  1 TTHM and 1 HAA5 sample per year at different locations
                                                       and time if the highest TTHM and HAA5 occurred at
                                                       different locations and/or time or 1 dual sample set per
                                                       year if the highest TTHM and HAA5 occurred at the same
                                                       location and time of year, taken during the peak
                                                       historical month for DBP concentrations or (if unknown)
                                                       month of warmest water temperature.
500 to 4,999........................................  1 TTHM and 1 HAA5 sample per quarter at different
                                                       locations if the highest TTHM and HAA5 occurred at
                                                       different locations or 1 dual sample set per quarter if
                                                       the highest TTHM and HAA5 occurred at the same location.
5,000 to 9,999......................................  2 dual sample sets per quarter.
10,000 to 24,999....................................  4 dual sample sets per quarter.
25,000 to 49,999....................................  6 dual sample sets per quarter.
50,000 to 99,999....................................  8 dual sample sets per quarter.

[[Page 49676]]

 
100,000 to 499,999..................................  12 dual sample sets per quarter.
500,000 to 1,499,999................................  16 dual sample sets per quarter.
1,500,000 to 4,999,999..............................  20 dual sample sets per quarter.
=5,000,000...............................  24 dual sample sets per quarter.
-----------------------------------------------------
                            Ground Water Consecutive Systems That Buy All Their Water
----------------------------------------------------------------------------------------------------------------
<500................................................  1 TTHM and 1 HAA5 sample per year at different locations
                                                       and time if the highest TTHM and HAA5 occurred at
                                                       different locations and/or time or 1 dual sample set per
                                                       year if the highest TTHM and HAA5 occurred at the same
                                                       location and time of year, taken during the peak
                                                       historical month for DBP concentrations, or, if unknown,
                                                       during month of warmest water temperature.
500 to 9,999........................................  2 dual sample sets per year. Must be taken during the peak
                                                       historical month for DBP concentrations.
10,000 to 99,999....................................  4 dual sample sets per quarter.
100,000 to 499,999..................................  6 dual sample sets per quarter.
=500,000.................................  8 dual sample sets per quarter.
----------------------------------------------------------------------------------------------------------------

    (2) You must select Subpart V monitoring locations based on subpart 
L compliance monitoring results collected during the period of the IDSE 
and IDSE monitoring results. You must follow the protocol in paragraphs 
(e)(2)(i) through (iv) of this section, unless you provide a rationale 
for recommending different locations. If required to monitor at more 
than four locations, you must repeat the protocol as necessary, 
alternating between sites with the highest HAA5 LRAA and the highest 
TTHM LRAA not previously selected as a subpart V monitoring location 
for choosing locations under paragraph (e)(2)(iii) of this section.
    (i) Location with the highest TTHM LRAA not previously selected as 
a subpart V monitoring location.
    (ii) Location with the highest HAA5 LRAA not previously selected as 
a subpart V monitoring location.
    (iii) Existing subpart L average residence time compliance 
monitoring location.
    (iv) Location with the highest TTHM LRAA not previously selected as 
a subpart V monitoring location.
    (3) You may recommend locations other than those in paragraph 
(e)(2) of this section if you include a rationale for selecting other 
locations. If the State approves, you must monitor at these locations 
to determine compliance under subpart V.
    (4) If you used the 40/30 certification in Sec.  141.603(b) and do 
not have sufficient subpart L monitoring locations to identify the 
required number of Subpart V compliance monitoring locations, you must 
identify additional locations by selecting a site representative of 
maximum residence time and then a site representative of average 
residence time and repeating until the required number of compliance 
monitoring locations have been identified.
    (f) You must schedule samples during the peak historical month for 
TTHM and HAA5 concentration, unless the State approves another month. 
Once you have identified the peak historical month, and if you are 
required to conduct routine monitoring at least quarterly, you must 
schedule subpart V compliance monitoring at a regular frequency of 
approximately every 90 days or fewer.
    18. Part 141 is amended by adding new subpart V to read as follows:
Subpart V--Stage 2B Disinfection Byproducts Requirements
Sec.
141.620 General requirements.
141.621 Routine monitoring.
141.622 Subpart V monitoring plan.
141.623 Reduced monitoring.
141.624 Additional requirements for consecutive systems.
141.625 Conditions requiring increased monitoring.
141.626 Significant excursions.
141.627 Requirements for remaining on reduced TTHM and HAA5 
monitoring based on subpart L results.
141.628 Requirements for remaining on increased TTHM and HAA5 
monitoring based on subpart L results.
141.629 [Reserved]
141.630 Reporting and recordkeeping requirements.

Subpart V--Stage 2B Disinfection Byproducts Requirements


Sec.  141.620  General requirements.

    (a) The requirements of subpart V constitute national primary 
drinking water regulations. These regulations establish requirements 
for control of certain disinfection byproducts that supercede some 
requirements in subpart L and that are in addition to other 
requirements that are currently required under subpart L of this part. 
The regulations in this subpart establish monitoring and other 
requirements for achieving compliance with maximum contaminant levels 
for total trihalomethanes (TTHM) and haloacetic acids (five)(HAA5).
    (b) Applicability. You are subject to these requirements if your 
system is a community water system or nontransient noncommunity water 
system that adds a primary or residual disinfectant other than 
ultraviolet light or delivers water that has been treated with a 
primary or residual disinfectant other than ultraviolet light.
    (c) Schedule. You must comply with the requirements in this subpart 
on the schedule in the following table, based on your system type.

------------------------------------------------------------------------
   If you are this type of       You must comply with subpart V by: \1\
            system                              \2\ \3\
------------------------------------------------------------------------
(1) Subpart H serving =10,000.                    final rule].
(2) Subpart H serving <10,000  [date 90 mos following publication of
                                final rule] if no Cryptosporidium
                                monitoring is required under Sec.
                                141.706(c) OR
                               [date 102 mos following publication of
                                final rule] if Cryptosporidium
                                monitoring is required under Sec.
                                141.706(c).
(3) Ground water serving =10,000.                final rule].
(4) Ground water serving       [date 90 mos following publication of
 <10,000.                       final rule].

[[Page 49677]]

 
(5) Consecutive system.......  --at the same time as the system with the
                                earliest compliance date in the combined
                                distribution system.
------------------------------------------------------------------------
\1\ The State may grant up to an additional 24 months for compliance if
  you require capital improvements.
\2\ If you are required to conduct quarterly monitoring, you must begin
  monitoring in the first full calendar quarter that follows the
  compliance date in this table. If you are required to conduct
  monitoring at a frequency that is less than quarterly, you must begin
  monitoring in the calendar month recommended in the IDSE report
  prepared under Sec.   141.604 no later than 12 months after the
  compliance date in this table. If you are not required to submit an
  IDSE report, you must begin monitoring during the calendar month
  identified in the monitoring plan developed under Sec.   141.622 no
  later than 12 months after the compliance date.
\3\ If you are required to conduct quarterly monitoring, you must make
  compliance calculations at the end of the fourth calendar quarter that
  follows the compliance date and at the end of each subsequent quarter
  (or earlier if the LRAA calculated based on fewer than four quarters
  of data would cause the MCL to be exceeded regardless of the
  monitoring results of subsequent quarters). If you are required to
  conduct monitoring at a frequency that is less than quarterly, you
  must make compliance calculations beginning with the first compliance
  sample taken after the compliance date.

    (d) Monitoring and compliance. You must monitor at sampling 
locations identified in your monitoring plan developed under Sec.  
141.622. To determine compliance with subpart V MCLs, you must 
calculate locational running annual averages for TTHM and HAA5 using 
monitoring results collected under this subpart. If you fail to 
complete four consecutive quarters of monitoring, you must calculate 
compliance with the MCL based on an average of the available data from 
the most recent four quarters.
    (e) Violations. You must comply with specific monitoring and 
reporting requirements. Failure to monitor in accordance with the 
monitoring plan required under Sec.  141.622 is a monitoring violation. 
Failure to monitor will also be treated as a monitoring violation for 
the entire period covered by a locational running annual average 
compliance calculation for the subpart V MCLs in Sec.  141.64(b)(3).
    (f) Additional provisions.
    (1) You may consider multiple wells drawing water from a single 
aquifer as one treatment plant for determining the minimum number of 
TTHM and HAA5 samples required, with State approval in accordance with 
criteria developed under Sec.  142.16(h)(5) of this chapter. Approvals 
made under Sec. Sec.  141.132(a)(2) and 141.601(d) remain in effect 
unless withdrawn by the State.
    (2) Consecutive systems. For the purposes of this subpart, you must 
determine whether you buy all or some of your water based on your 
categorization for the IDSE under subpart U, unless otherwise directed 
by the State. If you were not categorized under subpart U, you must 
determine whether you buy all or some of your water based on your 
categorization during 2005, unless otherwise directed by the State.
    (3) For the purposes of determining monitoring requirements of this 
subpart, each consecutive system entry point from a wholesale system to 
a consecutive system that buys some, but not all, of its finished water 
is considered a treatment plant for that consecutive system.
    (i) You may request that the State allow multiple consecutive 
system entry points from a single wholesale system to a single 
consecutive system to be considered one treatment plant.
    (ii) In the request to the State for approval of multiple 
consecutive system entry points to be considered one treatment plant, 
you must demonstrate that factors such as relative locations of entry 
points, detention times, sources, and the presence of treatment (such 
as corrosion control or booster disinfection) will have a minimal 
differential effect on TTHM and HAA5 formation associated with 
individual entry points.


Sec.  141.621  Routine monitoring.

    (a) You must monitor at the locations and frequencies listed in the 
following table.

----------------------------------------------------------------------------------------------------------------
                                                                                 At these locations for each
   If you are this type of system            Then you must monitor                   treatment plant \1\
----------------------------------------------------------------------------------------------------------------
(1) Subpart H serving =10,000.                          treatment plant, taken approximately   in the IDSE report submitted under
                                      every 90 days. One quarterly set       subpart U.
                                      must be taken during the peak
                                      historical month for DBP
                                      concentrations \2\.
(2) Subpart H serving 500-9,999....  two dual sample sets per quarter per   --locations recommended to the State
                                      treatment plant, taken approximately   in the IDSE report submitted under
                                      every 90 days. One quarterly set       subpart U.\3\
                                      must be taken during the peak
                                      historical month for DBP
                                      concentrations \2\.
(3) Subpart H serving <500.........  one TTHM and one HAA5 sample per year  --locations recommended to the State
                                      per treatment plant, taken during      in the IDSE report submitted under
                                      the peak historical month for DBP      subpart U.\4\
                                      concentrations.
(4) Ground water serving =10,000.                          treatment plant, taken approximately   in the IDSE report submitted under
                                      every 90 days. One quarterly set       subpart U.\3\
                                      must be taken during the peak
                                      historical month for DBP
                                      concentrations \2\.
(5) Ground water serving 500-9,999.  two dual sample sets per year per      --locations recommended to the State
                                      treatment plant, taken during the      in the IDSE report submitted under
                                      peak historical month for DBP          subpart U.\3\
                                      concentrations \2\.
(6) Ground water serving <500......  one TTHM and one HAA5 sample per year  --locations recommended to the State
                                      per treatment plant, taken during      in the IDSE report submitted under
                                      the peak historical month for DBP      subpart U.\4\
                                      concentrations.
(7) Consecutive system that buys     based on your own population and       --locations recommended to the State
 some, but not all, of its finished   source water, except that              in the IDSE report submitted under
 water.                               consecutive systems that receive       subpart U.
                                      water from a subpart H system must
                                      monitor as a subpart H system.

[[Page 49678]]

 
(8) Consecutive system that buys     as specified in Sec.   141.605(e)....  --locations recommended to the State
 all its finished water.                                                     in the IDSE report submitted under
                                                                             subpart U.
----------------------------------------------------------------------------------------------------------------
\1\ Unless the State has approved or required other locations or additional locations based on the IDSE report
  or other information, or you have updated the monitoring plan under Sec.   141.622.
\2\ A dual sample set is a set of two samples collected at the same time and same location, with one sample
  analyzed for TTHM and the other sample analyzed for HAA5.
\3\ If you have a single location that has both the highest TTHM LRAA and highest HAA5 LRAA, you may take a dual
  sample set only at that location after approval by the State.
\4\ You are required to sample for both TTHM and HAA5 at one location if that location is the highest for both
  TTHM and HAA5. If different locations have high TTHM and HAA5 LRAAs, you may sample for TTHM only at the high
  TTHM location and for HAA5 only at the high HAA5 location. If you have received a very small system waiver for
  IDSE monitoring from the State under Sec.   141.603(c), you must monitor for TTHM and HAA5 as a dual sample
  set at the subpart L monitoring location (a point representative of maximum residence time) during the month
  of warmest water temperature.

    (b) You must begin monitoring at the locations you have recommended 
in your IDSE report submitted under Sec.  141.604 following the 
schedule in Sec.  141.620(c), unless the State requires other locations 
or additional locations after its review. If you have received a very 
small system waiver under Sec.  141.603(c), you must monitor at the 
location(s) identified in your monitoring plan in Sec.  141.132(f), 
updated as required by Sec.  141.622.
    (c) You must use an approved method listed in Sec.  141.131 for 
TTHM and HAA5 analyses in this subpart. Analyses must be conducted by 
laboratories that have received certification by EPA or the State as 
specified in Sec.  141.131.


Sec.  141.622  Subpart V monitoring plan.

    (a) You must develop and implement a monitoring plan to be kept on 
file for State and public review. You may comply by updating the 
monitoring plan developed under Sec.  141.132(f) no later than the date 
identified in Sec.  141.620(c) for subpart V compliance. If you have 
received a very small system waiver under Sec.  141.603(c), you must 
comply by updating the monitoring plan developed under Sec.  141.132(f) 
no later than the date identified in Sec.  141.620(c) for subpart V 
compliance. The monitoring plan must contain the elements in paragraphs 
(a)(1) through (a)(5) of this section:
    (1) Monitoring locations;
    (2) Monitoring dates;
    (3) Compliance calculation procedures;
    (4) Monitoring plans for any other systems in the combined 
distribution system if monitoring requirements have been modified based 
on data from other systems; and
    (5) Any permits, contracts, or agreements with third parties 
(including other PWSs, laboratories, and State agencies) to sample, 
analyze, report, or perform any other system requirement in this 
subpart.
    (b) The monitoring plan will reflect the recommendations of the 
IDSE report required under subpart U, along with any State-mandated 
modifications. The State must approve any monitoring sites for which 
you are required to provide a rationale in your IDSE report by Sec.  
141.605(a)(4).
    (c) If you are a subpart H system serving more than 3,300 people, 
you must submit a copy of your monitoring plan to the State prior to 
the date you are required to comply with the monitoring plan.
    (d) You may modify your monitoring plan to reflect changes in 
treatment, distribution system operations and layout (including new 
service areas), or other factors that may affect TTHM or HAA5 
formation. If you change monitoring locations, you must replace 
locations with the lowest LRAA and notify the State how new sites were 
selected as part of the next report due under Sec.  141.630. The State 
may also require modifications in your monitoring plan.


Sec.  141.623  Reduced monitoring.

    (a) Systems other than consecutive systems that buy all their 
water. You may reduce monitoring by meeting the criteria in the table 
in this paragraph at all treatment plants in the system. You may only 
use data collected under the provisions of this subpart or subpart L of 
this part to qualify for reduced monitoring.

----------------------------------------------------------------------------------------------------------------
                                      Then you may reduce     To reduce monitoring per plant at these locations/
                                     monitoring if you have                        frequency
  If you are this type of system    monitoring results under ---------------------------------------------------
                                       Sec.   141.621 and               TTHM                      HAA5
----------------------------------------------------------------------------------------------------------------
(1) Subpart H serving =10,000.                        L for TTHM and <=0.030     quarter by taking a       quarter by taking a
                                    for HAA5 at ALL            dual sample set at the    dual sample set at the
                                    monitoring locations,      location with the         location with the
                                    AND                        highest TTHM LRAA or      highest HAA5 LRAA or
                                                               single measurement.       single measurement.
                                   --the source water annual
                                    average TOC level,
                                    before any treatment, is
                                    <=4.0 mg/L at each
                                    subpart H treatment
                                    plant \1\.
(2) Subpart H serving 500-9,999..  --the LRAA is <=0.040 mg/  --monitor once per year   --monitor once per year
                                    L for TTHM and <=0.030     by taking a dual sample   by taking a dual sample
                                    for HAA5 at ALL            set at the location       set at the location
                                    monitoring locations,      with the highest TTHM     with the highest HHA5
                                    AND                        single measurement        single measurement
                                                               during the quarter that   during the quarter that
                                                               the highest single TTHM   the highest single HHA5
                                                               measurement occurred      measurement
                                                               \2\.                      occurred.\2\
                                   --the source water annual
                                    average TOC level,
                                    before any treatment, is
                                    <=4.0 mg/L at each
                                    subpart H treatment
                                    plant \1\.
(3) Subpart H serving <500.......  --monitoring may not be    not applicable..........  not applicable.
                                    reduced to fewer than
                                    one TTHM sample and one
                                    HAA5 sample per year.
(4) Ground water serving =10,000.                        L for TTHM and <=0.030     by taking a dual sample   by taking a dual sample
                                    for HAA5 at ALL            set at the location       set at the location
                                    monitoring locations.      with the highest TTHM     with the highest HHA5
                                                               single measurement        single measurement
                                                               during the quarter that   during the quarter that
                                                               the highest single TTHM   the highest single HHA5
                                                               measurement occurred      measurement
                                                               \2\.                      occurred.\2\

[[Page 49679]]

 
(5) Ground water serving 500-      --the LRAA is <=0.040 mg/  --monitor once every      --monitor once every
 9,999.                             L for TTHM and <=0.030     third year by taking a    third year by taking a
                                    for HAA5 at ALL            dual sample set at the    dual sample set at the
                                    monitoring locations.      location with the         location with the
                                                               highest TTHM single       highest HHA5 single
                                                               measurement during the    measurement during the
                                                               quarter that the          quarter that the
                                                               highest single TTHM       highest single HHA5
                                                               measurement occurred      measurement
                                                               \2\.                      occurred.\2\
(6) Ground water serving <500....  --the LRAA is <=0.040 mg/  --monitor once every      --monitor once every
                                    L for TTHM and <=0.030     third year for TTHM at    third year for HAA5 at
                                    for HAA5 at ALL            the location with the     the location with the
                                    monitoring locations.      highest TTHM single       highest HAA5 single
                                                               measurement during the    measurement during the
                                                               quarter that the          quarter that the
                                                               highest single TTHM       highest single HAA5
                                                               measurement occurred      measurement
                                                               \2\.                      occurred.\2\
(7) Consecutive system that buys   --the LRAA is <=0.040 mg/  --monitor at the          --monitor at the
 some, but not all, of its          L for TTHM and <=0.030     location(s) and           location(s) and
 finished water \3\.                for HAA5 at ALL            frequency associated      frequency associated
                                    monitoring locations.      with a non-consecutive    with a non-consecutive
                                                               system with the same      system with the same
                                                               population and source     population and source
                                                               water type.               water type.\2\
----------------------------------------------------------------------------------------------------------------
\1\ TOC monitoring must comply with the provisions of either Sec.   141.132(d) or Sec.   141.132(e).
\2\ If your location for reduced monitoring for TTHM and HAA5 is the same location and if your quarter for the
  highest TTHM and HAA5 single measurement is the same, you may take one dual sample set at that location during
  that quarter.
\3\ Consecutive systems that buy some, but not all, of their finished water may reduce monitoring based on their
  own population and their wholesale system(s)'s source water type to the frequency and location(s) required in
  this section, unless the consecutive system treats surface water or ground water under the direct influence of
  surface water. If the consecutive system treats surface water or ground water under the direct influence of
  surface water, it must base reduced monitoring on its population and classification as a subpart H system.

    (b) Consecutive systems that buy all their water. You may reduce 
monitoring to the level specified in the table in this paragraph if the 
LRAA is <=0.040 mg/L for TTHM and <=0.030 mg/L for HAA5 at all 
monitoring locations. You may only use data collected under the 
provisions of this subpart or subpart L of this part to qualify for 
reduced monitoring.

 Reduced Monitoring Frequency for Consecutive Systems That Buy All Their
                                 Water.
------------------------------------------------------------------------
                                                  Reduced monitoring
                 Population                     frequency and location
------------------------------------------------------------------------
                            Subpart H systems
------------------------------------------------------------------------
<500.......................................  Monitoring may not be
                                              reduced.
500 to 4,999...............................  1 TTHM and 1 HAA5 sample
                                              per year at different
                                              locations or during
                                              different quarters if the
                                              highest TTHM and HAA5
                                              measurements occurred at
                                              different locations or
                                              different quarters or 1
                                              dual sample set per year
                                              if the highest TTHM and
                                              HAA5 measurements occurred
                                              at the same location and
                                              quarter.
5,000 to 9,999.............................  2 dual sample sets per
                                              year; one at the location
                                              with the highest TTHM
                                              single measurement during
                                              the quarter that the
                                              highest single TTHM
                                              measurement occurred, one
                                              at the location with the
                                              highest HAA5 single
                                              measurement during the
                                              quarter that the highest
                                              single HAA5 measurement
                                              occurred.
10,000 to 24,999...........................  2 dual sample sets per
                                              quarter at the locations
                                              with the highest TTHM and
                                              highest HAA5 LRAAs.
25,000 to 49,999...........................  2 dual sample sets per
                                              quarter at the locations
                                              with the highest TTHM and
                                              highest HAA5 LRAAs.
50,000 to 99,000...........................  4 dual sample sets per
                                              quarter--at the locations
                                              with the two highest TTHM
                                              and two highest HAA5
                                              LRAAs.
100,000 to 499,999.........................  4 dual sample sets per
                                              quarter--at the locations
                                              with the two highest TTHM
                                              and two highest HAA5
                                              LRAAs.
500,000 to 1,499,999.......................  6 dual sample sets per
                                              quarter--at the locations
                                              with the three highest
                                              TTHM and three highest
                                              HAA5 LRAAs.
1,500,000 to 4,999,999.....................  6 dual sample sets per
                                              quarter--at the locations
                                              with the three highest
                                              TTHM and three highest
                                              HAA5 LRAAs.
=5,000,000......................  8 dual sample sets per
                                              quarter at the locations
                                              with the four highest TTHM
                                              and four highest HAA5
                                              LRAAs.
--------------------------------------------
                          Ground water systems
------------------------------------------------------------------------
<500.......................................  1 TTHM and 1 HAA5 sample
                                              every third year at
                                              different locations and
                                              time if the highest TTHM
                                              and HAA5 measurements
                                              occurred at different
                                              locations and/or time or 1
                                              dual sample set every
                                              third year if the highest
                                              TTHM and HAA5 measurements
                                              occurred at the same
                                              location and time of year.
500 to 9,999...............................  1 TTHM and 1 HAA5 sample
                                              every year at different
                                              locations and time if the
                                              highest TTHM and HAA5
                                              measurements occurred at
                                              different locations and/or
                                              time or 1 dual sample set
                                              every year if the highest
                                              TTHM and HAA5 measurements
                                              occurred at the same
                                              location and time of year.
10,000 to 99,000...........................  2 dual sample sets per
                                              year; one at the location
                                              with the highest TTHM
                                              single measurement during
                                              the quarter that the
                                              highest single TTHM
                                              measurement occurred and
                                              one at the location with
                                              the highest HAA5 single
                                              measurement during the
                                              quarter that the highest
                                              single HAA5 measurement
                                              occurred.
100,000 to 499,999.........................  2 dual sample sets per
                                              quarter; at the locations
                                              with the highest TTHM and
                                              highest HAA5 LRAAs.
=500,000........................  4 dual sample sets per
                                              quarter; at the locations
                                              with the two highest TTHM
                                              and two highest HAA5
                                              LRAAs.
------------------------------------------------------------------------

    (c) You may remain on reduced monitoring as long as the TTHM LRAA 
<=0.040 mg/L and the HAA5 LRAA <=0.030 mg/L at each monitoring location 
(for systems with quarterly monitoring) or each TTHM sample <=0.060 mg/
L and each HAA5 sample <=0.045 mg/L (for systems with annual or less 
frequent monitoring). In addition, the source water annual average TOC 
level, before any treatment, must be <=4.0 mg/L at each treatment plant 
treating surface water or ground water under the direct influence of 
surface water, based on monitoring conducted under either Sec. Sec.  
141.132(d) or 141.132(e). If the LRAA at any location exceeds either 
0.040 mg/L for TTHM or 0.030 mg/L for HAA5 or if the annual (or less 
frequent) sample at any location exceeds either 0.060 mg/L for TTHM or 
0.045 mg/L for HAA5, or if the source water annual average TOC level, 
before any treatment, 4.0 mg/L at any treatment plant 
treating surface water or ground water under the direct influence of 
surface water, the system must resume routine monitoring

[[Page 49680]]

under Sec.  141.621 for all treatment plants or begin increased 
monitoring for all treatment plants if Sec.  141.625 applies.
    (d) The State may return your system to routine monitoring at the 
State's discretion.


Sec.  141.624  Additional requirements for consecutive systems.

    If you are a consecutive system that does not add a disinfectant 
but delivers water that has been disinfected with other than 
ultraviolet light, you must comply with monitoring requirements for 
chlorine and chloramines in Sec.  141.132(c)(1) and the compliance 
requirements in Sec.  141.133(c)(1) beginning [date three years after 
publication of final rule] and report monitoring results under Sec.  
141.134(c), unless required earlier by the State.


Sec.  141.625  Conditions requiring increased monitoring.

    (a) If you are required to monitor at a particular location yearly 
or less frequently than yearly under Sec. Sec.  141.621 or 141.623, you 
must increase monitoring to dual sample sets once per quarter (taken 
approximately every 90 days) at all locations if either the annual (or 
less frequent) TTHM sample 0.080 mg/L or the annual (or less 
frequent) HAA5 sample 0.060 mg/L at any location.
    (b) You are not in violation of the MCL until the LRAA calculated 
based on four consecutive quarters of monitoring (or the LRAA 
calculated based on fewer than four quarters of data if the MCL would 
be exceeded regardless of the monitoring results of subsequent 
quarters) exceeds the subpart V MCLs in Sec.  141.64(b)(3). You are in 
violation of the monitoring requirements for each quarter that a 
monitoring result would be used in calculating an LRAA if you fail to 
monitor.
    (c) You may return to routine monitoring once you have conducted 
increased monitoring for at least four consecutive quarters and the 
LRAA for every location is <=0.060 mg/L for TTHM and <=0.045 mg/L for 
HAA5.


Sec.  141.626  Significant excursions.

    If a significant excursion occurs, you must conduct a significant 
excursion evaluation and prepare a written report of the evaluation no 
later than 90 days after being notified of the analytical result that 
shows the significant excursion. You must discuss the evaluation with 
the State no later than the next sanitary survey for your system. Your 
evaluation must include an examination of distribution system 
operational practices that may contribute to TTHM and HAA5 formation 
(such as flushing programs and storage tank operations and excess 
capacity) and how these practices may be modified to reduce TTHM and 
HAA5 levels.


Sec.  141.627  Requirements for remaining on reduced TTHM and HAA5 
monitoring based on subpart L results.

    You may remain on reduced monitoring after the dates identified in 
Sec.  141.620(c) for compliance with this subpart only if you qualify 
for a 40/30 certification under Sec.  141.603(b) or have received a 
very small system waiver under Sec.  141.603(c), plus you meet the 
reduced monitoring criteria in Sec.  141.623(c), and you do not change 
or add monitoring locations from those used for compliance monitoring 
under subpart L. If your monitoring locations under this subpart differ 
from your monitoring locations under subpart L, you may not remain on 
reduced monitoring after the dates identified in Sec.  141.620(c) for 
compliance with this subpart.


Sec.  141.628  Requirements for remaining on increased TTHM and HAA5 
monitoring based on subpart L results.

    If you were on increased monitoring under subpart L, you must 
remain on increased monitoring until you qualify for a return to 
routine monitoring under Sec.  141.625(c). You must conduct increased 
monitoring under Sec.  141.625 at the monitoring locations in the 
monitoring plan developed under Sec.  141.622 beginning at the date 
identified in Sec.  141.620(c) for compliance with this subpart and 
remain on increased monitoring until you qualify for a return to 
routine monitoring under Sec.  141.625(c).


Sec.  141.629  [Reserved]


Sec.  141.630  Reporting and recordkeeping requirements.

    (a) Reporting. (1) You must report the following information for 
each monitoring location to the State within 10 days of the end of any 
quarter in which monitoring is required:
    (i) Number of samples taken during the last quarter.
    (ii) Date and results of each sample taken during the last quarter.
    (iii) Arithmetic average of quarterly results for the last four 
quarters (LRAAs).
    (iv) Whether the MCL was violated.
    (2) If you are a subpart H system seeking to qualify for or remain 
on reduced TTHM/HAA5 monitoring, you must report the following source 
water TOC information for each treatment plant that treats surface 
water or ground water under the direct influence of surface water to 
the State within 10 days of the end of any quarter in which monitoring 
is required:
    (i) The number of source water TOC samples taken each month during 
last quarter.
    (ii) The date and result of each sample taken during last quarter.
    (iii) The quarterly average of monthly samples taken during last 
quarter.
    (iv) The running annual average (RAA) of quarterly averages from 
the past four quarters.
    (v) Whether the RAA exceeded 4.0 mg/L.
    (b) Recordkeeping. You must retain any subpart V monitoring plans 
and your subpart V monitoring results as required by Sec.  141.33.

PART 142-- NATIONAL PRIMARY DRINKING WATER REGULATIONS 
IMPLEMENTATION

    1. 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.

    2. Section 142.14 is amended by adding paragraph (a)(8) to read as 
follows:


Sec.  142.14  Records kept by States.

    (a) * * *
    (8) Any decisions made pursuant to the provisions of 40 CFR part 
141, subparts U and V of this chapter.
    (i) Those systems for which the State has determined that the 40 
CFR part 141, subpart L approved monitoring site is representative of 
the highest TTHM and HAA5 and therefore have been granted a very small 
system waiver under Sec.  141.603(c) of this chapter. The State must 
provide a copy of the decision to the system. A copy of the decision 
must be kept until reversed or revised.
    (ii) System IDSE reports, plus any modifications required by the 
State. Reports must be kept until reversed or revised in their 
entirety.
* * * * *
    3. Section 142.16 is amended by adding paragraph (m) to read as 
follows:


Sec.  142.16  Special primacy conditions.

* * * * *
    (m) Requirements for States to adopt 40 CFR part 141, subparts U 
and V. 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, subparts U

[[Page 49681]]

and V, must contain a description of how the State will accomplish the 
following:
    (1) For PWSs serving fewer than 500 people, a very small system 
waiver procedure for subpart U IDSE requirements that will apply to all 
systems that serve fewer than 500 people without the State making a 
system-by-system waiver determination, if the State elects to use such 
an authority.
    (2) A procedure for evaluating system-specific studies under Sec.  
141.603(a) of this chapter, if system-specific studies are conducted in 
the State.
    (3) A procedure for determining that multiple consecutive system 
entry points from a single wholesale system to a single consecutive 
system should be treated as a single treatment plant for monitoring 
purposes.
    (4) A procedure for addressing consecutive systems outside the 
provisions of Sec.  141.29 of this chapter or part 141 subparts U and V 
of this chapter, if the State elects to use such an authority.
    (5) A procedure for systems to identify significant excursions.

PART 143--NATIONAL SECONDARY DRINKING WATER REGULATIONS

    1. The authority citation for part 143 continues to read as 
follows:

    Authority: 42 U.S.C. 300f et seq.

    2. In Sec.  143.4, the table in paragraph (b) is amended by 
revising entries 2 and 9 and footnotes 3 and 4, and by adding footnote 
6 to read as follows:


Sec.  143.4  Monitoring.

* * * * *
    (b) * * *

----------------------------------------------------------------------------------------------------------------
                                                                    SM 4 18th and
         Contaminant                 EPA             ASTM 3           19th ed.       SM 4 20th ed.      Other
----------------------------------------------------------------------------------------------------------------
 
                                                  * * * * * * *
2. Chloride..................         300.0 1  D4327-97.........  4110 B..........  4110 B.........
                                      300.1 6  .................  ................  ...............
                                               .................  4500-Cl -D......  4500-Cl -D.....  ...........
                                               D512-89B.........  4500-Cl-B.......  4500-Cl-B......  ...........
 
                                                  * * * * * * *
9. Sulfate...................         300.0 1  D4327-97.........  4110B...........  4110B..........
                                      300.1 6  .................  ................  ...............  ...........
                                      375.2 1  .................  4500-SO4 2-F....  4500-SO4 2-F...
                                                                  4500-SO4 2-C, D.  4500-SO 4 2-C,
                                                                                     D.
                                               D516-90..........  4500-SO4 2-E....  4500-SO4 2-E...
 
                                                 * * * * * * *
----------------------------------------------------------------------------------------------------------------
* * * * *
1 ``Methods for the Determination of Inorganic Substances in Environmental Samples'', EPA/600/R-93-100, August
  1993. Available at NTIS, PB94-120821.
* * * * *
3 Annual Book of ASTM Standards, 1994, 1996, or 1999, Vols. 11.01 and 11.02, ASTM International; any year
  containing the cited version of the method may be used. Copies may be obtained from ASTM International, 100
  Barr Harbor Drive, West Conshohocken, PA 19428.
4 Standard Methods for the Examination of Water and Wastewater, 18th edition (1992), 19th edition (1995), or
  20th edition (1998). American Public Health Association, 1015 Fifteenth Street, NW, Washington, DC 20005. The
  cited methods published in any of these three editions may be used, except that the versions of 3111 B, 3111
  D, and 3113 B in the 20th edition may not be used.
* * * * *
6 ``Methods for the Determination of Organic and Inorganic Compounds in Drinking Water'', Vol. 1, EPA 815-R-00-
  014, August 2000. Available at NTIS, PB2000-106981.

[FR Doc. 03-18149 Filed 8-15-03; 8:45 am]
BILLING CODE 6560-50-P