[Federal Register Volume 63, Number 241 (Wednesday, December 16, 1998)]
[Rules and Regulations]
[Pages 69390-69476]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-32887]



[[Page 69389]]

_______________________________________________________________________

Part IV





Environmental Protection Agency





_______________________________________________________________________



40 CFR Parts 9, 141, and 142



National Primary Drinking Water Regulations: Disinfectants and 
Disinfection Byproducts; Final Rule

  Federal Register / Vol. 63, No. 241 / Wednesday, December 16, 1998 / 
Rules and Regulations  

[[Page 69390]]



ENVIRONMENTAL PROTECTION AGENCY

40 CFR Parts 9, 141, and 142

[WH-FRL-6199-8]
RIN 2040-AB82


National Primary Drinking Water Regulations: Disinfectants and 
Disinfection Byproducts

AGENCY: Environmental Protection Agency (EPA).

ACTION: Final rule.

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

SUMMARY: In this document, EPA is finalizing maximum residual 
disinfectant level goals (MRDLGs) for chlorine, chloramines, and 
chlorine dioxide; maximum contaminant level goals (MCLGs) for four 
trihalomethanes (chloroform, bromodichloromethane, 
dibromochloromethane, and bromoform), two haloacetic acids 
(dichloroacetic acid and trichloroacetic acid), bromate, and chlorite; 
and National Primary Drinking Water Regulations (NPDWRs) for three 
disinfectants (chlorine, chloramines, and chlorine dioxide), two groups 
of organic disinfection byproducts (total trihalomethanes (TTHMs)--a 
sum of the four listed above, and haloacetic acids (HAA5)--a sum of the 
two listed above plus monochloroacetic acid and mono-and dibromoacetic 
acids), and two inorganic disinfection byproducts (chlorite and 
bromate). The NPDWRs consist of maximum residual disinfectant levels 
(MRDLs) or maximum contaminant levels (MCLs) or treatment techniques 
for these disinfectants and their byproducts. The NPDWRs also include 
monitoring, reporting, and public notification requirements for these 
compounds. This document includes the best available technologies 
(BATs) upon which the MRDLs and MCLs are based. The set of regulations 
promulgated today is also know as the Stage 1 Disinfection Byproducts 
Rule (DBPR). EPA believes the implementation of the Stage 1 DBPR will 
reduce the levels of disinfectants and disinfection byproducts in 
drinking water supplies. The Agency believes the rule will provide 
public health protection for an additional 20 million households that 
were not previously covered by drinking water rules for disinfection 
byproducts. In addition, the rule will for the first time provide 
public health protection from exposure to haloacetic acids, chlorite (a 
major chlorine dioxide byproduct) and bromate (a major ozone 
byproduct).
    The Stage 1 DBPR applies to public water systems that are community 
water systems (CWSs) and nontransient noncommunity water systems 
(NTNCWs) that treat their water with a chemical disinfectant for either 
primary or residual treatment. In addition, certain requirements for 
chlorine dioxide apply to transient noncommunity water systems 
(TNCWSs).

EFFECTIVE DATE: This regulation is effective February 16, 1999. 
Compliance dates for specific components of the rule are discussed in 
the Supplementary Information Section. The incorporation by reference 
of certain publications listed in today's rule is approved by the 
Director of the Federal Register as of February 16, 1999.

ADDRESSES: Public comments, the comment/response document, applicable 
Federal Register documents, other major supporting documents, and a 
copy of the index to the public docket for this rulemaking are 
available for review at EPA's Drinking Water Docket: 401 M Street, SW., 
Washington, DC 20460 from 9 a.m. to 4 p.m., Eastern Standard Time, 
Monday through Friday, excluding legal holidays. For access to docket 
materials, please call 202/260-3027 to schedule an appointment and 
obtain the room number.

FOR FURTHER INFORMATION CONTACT: For general information contact, the 
Safe Drinking Water Hotline, Telephone (800) 426-4791. The Safe 
Drinking Water Hotline is open Monday through Friday, excluding Federal 
holidays, from 9:00 am to 5:30 pm Eastern Time. For technical 
inquiries, contact Tom Grubbs, Office of Ground Water and Drinking 
Water (MC 4607), U.S. Environmental Protection Agency, 401 M Street SW, 
Washington, DC 20460; telephone (202) 260-7270. For Regional contacts 
see Supplementary Information.

SUPPLEMENTARY INFORMATION: This regulation is effective 60 days after 
publication of Federal Register document for purposes of the 
Administrative Procedures Act and the Congressional Review Act. 
Compliance dates for specific components of the rule are discussed 
below. Solely for judicial review purposes, this final rule is 
promulgated as of 1 p.m. Eastern Time December 30, 1998, as provided in 
40 CFR 23.7.
    Regulated entities. Entities regulated by the Stage 1 DBPR are 
community and nontransient noncommunity water systems that add a 
disinfectant during any part of the treatment process including a 
residual disinfectant. In addition, certain provisions apply to 
transient noncommunity systems that use chlorine dioxide. Regulated 
categories and entities include:

----------------------------------------------------------------------------------------------------------------
                Category                                      Examples of regulated entities
----------------------------------------------------------------------------------------------------------------
Industry...............................  Community and nontransient noncommunity water systems that treat their
                                          water with a chemical disinfectant for either primary of residual
                                          treatment. In addition, certain requirements for chlorine dioxide
                                          apply to transient noncommunity water systems.
State, Local, Tribal, or Federal         Same as above.
 Governments.
----------------------------------------------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in this table could also be regulated. To determine whether 
your facility is regulated by this action, you should carefully examine 
the applicability criteria in Sec. 141.130 of this rule. If you have 
questions regarding the applicability of this action to a particular 
entity, contact one of the persons listed in the preceding FOR FURTHER 
INFORMATION CONTACT section or the Regional contacts below.

Regional Contacts

I. Kevin Reilly, Water Supply Section, JFK Federal Bldg., Room 203, 
Boston, MA 02203, (617) 565-3616
II. Michael Lowy, Water Supply Section, 290 Broadway 24th Floor, New 
York, NY 10007-1866, (212) 637-3830
III. Jason Gambatese, Drinking Water Section (3WM41), 1650 Arch Street, 
Philadelphia, PA 19103-2029, (215) 814-5759

[[Page 69391]]

IV. David Parker, Water Supply Section, 345 Courtland Street, Atlanta, 
GA 30365, (404) 562-9460
V. Miguel Del Toral, Water Supply Section, 77 W. Jackson Blvd., 
Chicago, IL 60604, (312) 886-5253
VI. Blake L. Atkins, Drinking Water Section, 1445 Ross Avenue, Dallas, 
TX 75202, (214) 665-2297
VII. Ralph Flournoy, Drinking Water/Ground Water Management Branch, 726 
Minnesota Ave., Kansas City, KS 66101, (913) 551-7374
VIII. Bob Clement, Public Water Supply Section (8P2-W-MS), 999 18th 
Street, Suite 500, Denver, CO 80202-2466, (303) 312-6653
IX. Bruce Macler, Water Supply Section, 75 Hawthorne Street, San 
Francisco, CA 94105, (415) 744-1884
X. Wendy Marshall, Drinking Water Unit, 1200 Sixth Avenue (OW-136), 
Seattle, WA 98101, (206) 553-1890

Abbreviations Used in This Document

AWWA: American Water Works Association
AWWSCo: American Water Works Service Company
BAT: Best available technology
BDCM: Bromodichloromethane
CDC: Centers for Disease Control and Prevention
C.I.: Confidence Intervals
CMA: Chemicals Manufacturers Association
CPE: Comprehensive performance evaluation
CWS: Community water system
DBCM: Dibromochloromethane
DBP: Disinfection byproducts
D/DBP: Disinfectants and disinfection byproducts
DBPR: Disinfection Byproducts Rule
DBPRAM: Disinfection byproducts regulatory analysis model
DCA: Dichloroacetic acid
DOC: Dissolved organic carbon
DWSRF: Drinking Water State Revolving Fund
EC: Enhanced coagulation
EJ: Environmental justice
EPA: United States Environmental Protection Agency
ESWTR: Enhanced Surface Water Treatment Rule
FACA: Federal Advisory Committee Act
GAC10: Granular activated carbon with ten minute empty bed contact time 
and 180 day reactivation frequency
GAC20: Granular activated carbon with twenty minute empty bed contact 
time and 180 day reactivation frequency
GDP: Gross Domestic Product
GWR: Groundwater rule
HAA5: Haloacetic acids (five)(chloroacetic acid, dichloroacetic acid, 
trichloroacetic acid, bromoacetic acid, and dibromoacetic acid)
HAN: Haloacetonitriles
ICR: Information collection rule (issued under section 1412(b) of the 
SDWA)
ILSI: International Life Sciences Institute
IESTWR: Interim Enhanced Surface Water Treatment Rule
LOAEL: Lowest Observed Adverse Effect Level
LT1ESTWR: Long-Term 1Enhanced Surface Water Treatment Rule
MCL: Maximum contaminant level
MCLG: Maximum contaminant level goal
M-DBP: Microbial and Disinfectants/Disinfection Byproducts
mg/L: Milligrams per liter
MRDL: Maximum residual disinfectant level
MRDLG: Maximum residual disinfectant level goal
NDWAC: National Drinking Water Advisory Council
NIST: National Institute of Science and Technology
NOAEL: No Observed Adverse Effect Level
NODA: Notice of Data Availability
NOM: Natural organic matter
NPDWR: National Primary Drinking Water Regulation
NTNCWS: Nontransient noncommunity water system
NTP: National Toxicology Program
NTTAA: National Technology Transfer and Advancement Act
NTU: Nephelometric turbidity unit
OMB: Office of Management and Budget
PAR: Population attributable risk
PBMS: Performance based measurement system
PE: Performance evaluation
PODR: Point of diminishing return
PQL: Practical quantitation limit
PWS: Public water system
QC: Quality control
Reg. Neg.: Regulatory Negotiation
RFA: Regulatory Flexibility Act
RfD: Reference dose
RIA: Regulatory impact analysis
RSC: Relative source contribution
SAB: Science Advisory Board
SBREFA: Small Business Regulatory Enforcement Fairness Act
SDWIS: Safe Drinking Water Information System
SUVA: Specific ultraviolet absorbance
SDWA: Safe Drinking Water Act, or the ``Act,'' as amended 1996
SWTR: Surface Water Treatment Rule
TC: Total coliforms
TCA: Trichloroacetic acid
TCR: Total Coliform Rule
TOC: Total organic carbon
TOX: Total organic halides
TTHM: Total trihalomethanes (chloroform, bromdichloromethane, 
dibromochloromethane, and bromoform)
TNCWS: Transient noncommunity water systems
TWG: Technical work group
UMRA: Unfunded mandates reform act
URTH: Unreasonable risk to health
WIDB: Water Industry Data Base

Table of Contents

I. Background
    A. Statutory Requirements and Legal Authority
    B. Regulatory History
    1. Existing Regulations
    2. Public Health Concerns To Be Addressed
    3. Regulatory Negotiation Process
    4. Federal Advisory Committee Process
    5. 1997 and 1998 Notices of Data Availability (NODA)
II. Summary of Final Stage 1 Disinfection Byproduct Rule
    A. Applicability
    B. MRDLGs and MRDLs for Disinfectants
    C. MCLGs and MCLs for TTHMs, HAA5, Chlorite, and Bromate
    D. Treatment Technique for Disinfection Byproducts Precursors
    E. BAT for Disinfectants, TTHMs, HAA5, Chlorite, and Bromate
    F. Compliance Monitoring Requirements
    G. Analytical Methods
    H. Laboratory Certification Criteria
    I. Variances and Exemptions
    J. State Recordkeeping, Primacy, Reporting Requirements
    K. System Reporting Requirements
    L. Guidance Manuals
    M. Regulation Review
III. Explanation of Final Rule
    A. MCLGs/MRDLGs
    1. MCLG for Chloroform
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    2. MCLG for Bromodichloromethane (BDCM)
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    3. MCLG for Dibromochloromethane (DBCM)
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    4. MCLG for Bromoform
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    5. MCLG for Dichloroacetic Acid (DCA)
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    6. MCLG for Trichloroacetic Acid (TCA)
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    7. MCLG for Chlorite and MRDLG for Chlorine Dioxide
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    8. MCLG for Bromate
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments

[[Page 69392]]

    9. MCLG for Chloral Hydrate
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    10. MRDLG for Chlorine
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    11. MRDLG for Chloramine
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    B. Epidemiology
    1. Cancer Epidemiology
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    2. Reproductive and Developmental Epidemiology
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    C. MCLs and BAT for TTHM, HAA5, Chlorite, and Bromate; MRDLs and 
BAT for Chlorine, Chloramines, and Chlorine Dioxide
    1. MCLs for TTHMs and HAA5
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    2. MCL for Bromate
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    3. MCL for Chlorite
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    4. MRDL for Chlorine
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    5. MRDL for Chloramines
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    6. MRDL for Chlorine Dioxide
    a. Today's Rule
    b. Background Analysis
    c. Summary of Comments
    D. Treatment Technique Requirement
    1. Today's Rule
    2. Background and Analysis
    3. Summary of Comments
    E. Predisinfection Disinfection Credit
    1. Today's Rule
    2. Background and Analysis
    3. Summary of Comments
    F. Requirements for Systems to Use Qualified Operators
    G. Analytical Methods
    1. Today's Rule
    2. Background and Analysis
    3. Summary of Comments
    4. Performance Based Measurement Systems
    H. Monitoring Requirements
    1. Today's Rule
    2. Background and Analysis
    3. Summary of Comments
    I. Compliance Schedules
    1. Today's Rule
    2. Background and Analysis
    3. Summary of Comments
    J. Public Notice Requirements
    1. Today's Rule
    2. Background and Analysis
    3. Summary of Comments
    K. System Reporting and Record Keeping Requirements
    1. Today's Rule
    2. Summary of Comments
    L. State Recordkeeping, Primacy, and Reporting Requirements
    1. State Recordkeeping Requirements
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    2. Special Primacy Requirements
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    3. State Reporting Requirements
    a. Today's Rule
    b. Background and Analysis
    c. Summary of Comments
    M. Variances and Exemptions
    1. Today's Rule
    2. Background and Analysis
    3. Summary of Comments
    N. Laboratory Certification and Approval
    1. Today's Rule
    2. Background and Analysis
    3. Summary of Comments
IV. Economic Analysis
    A. Today's Rule
    B. Background
    1. Overview of RIA for the Proposed Rule
    2. Factors Affecting Changes to the 1994 RIA
    a. Changes in Rule Criteria
    b. New Information Affecting DBP Occurrence and Compliance 
Forecast
    c. New Epidemiology Information
    C. Cost Analysis
    1. Revised Compliance Forecast
    2. System Level Unit Costs
    3. National Costs
    D. Benefits Analysis
    1. Exposure Assessment
    2. Baseline Risk Assessment Based on TTHM Toxicological Data
    3. Baseline Analysis Based on Epidemiology Data
    4. Exposure Reduction Analysis
    5. Monetization of Health Endpoints
    E. Net Benefits Analysis
    F. Summary of Comments
V. Other Requirements
    A. Regulatory Flexibility Analysis
    1. Today's Rule
    2. Background and Analysis
    3. Summary of Comments
    B. Paperwork Reduction Act
    C. Unfunded Mandates Reform Act
    1. Summary of UMRA Requirements
    2. Written Statement for Rules with Federal Mandates of $100 
million or More
    a. Authorizing Legislation
    b. Cost Benefit Analysis
    c. Estimates of Future Compliance Costs and Disproportionate 
Budgetary Effects
    d. Macro-economic Effects
    e. Summary of State, Local, and Tribal Government and 
TheirConcerns
    f. Regulatory Alternative Considered
    3. Impacts on Small Governments
    D. National Technology Transfer and Advancement Act
    E. Executive Order 12866: Regulatory Planning and Review
    F. Executive Order 12898: Environmental Justice
    G. Executive Order 13045: Protection of Children from 
Environmental Health Risks and Safety Risks
    H. Consultation with the Science Advisory Board, National 
Drinking Water Advisory Council, and the Secretary of Health and 
Human Services
    I. Executive Order 12875: Enhancing the Intergovernmental 
Partnership
    J. Executive Order 13084: Consultation and Coordination with 
Indian Tribal Governments
    K. Submission to Congress and the General Accounting Office
    L. Likely Effect of Compliance with the Stage 1 DBPR on the 
Technical, Financial, and Managerial Capacity of Public Water 
Systems
VI. References

I. Background

A. Statutory Requirements and Legal Authority

    The Safe Drinking Water Act (SDWA or the Act), as amended in 1986, 
requires USEPA to publish a ``maximum contaminant level goal'' (MCLG) 
for each contaminant which, in the judgement of the USEPA 
Administrator, ``may have any adverse effect on the health of persons 
and which is known or anticipated to occur in public water systems'' 
(Section 1412(b)(3)(A)). MCLGs are to be set at a level at which ``no 
known or anticipated adverse effect on the health of persons occur and 
which allows an adequate margin of safety'' (Section 1412(b)(4)).
    The Act was amended in August 1996. As a result of these 
Amendments, several of these provisions were renumbered and augmented 
with additional language. Other sections were added establishing new 
drinking water requirements. These modifications are outlined below.
    The Act also requires that at the same time USEPA publishes an 
MCLG, which is a non-enforceable health goal, it also must publish a 
National Primary Drinking Water Regulation (NPDWR) that specifies 
either a maximum contaminant level (MCL) or treatment technique 
(Sections 1401(1) and 1412(a)(3)). USEPA is authorized to promulgate a 
NPDWR ``that requires the use of a treatment technique in lieu of 
establishing a MCL,'' if the Agency finds that ``it is not economically 
or technologically feasible to ascertain the level of the 
contaminant''.
    As amended, EPA's general authority to set a maximum contaminant 
level goal (MCLG) and National Primary Drinking Water Regulation 
(NPDWR) applies to contaminants that may ``have an adverse effect on 
the health of persons,'' that are ``known to occur or there is a 
substantial likelihood that the contaminant will occur in public water

[[Page 69393]]

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)).
    The amendments, also require EPA, when proposing a NPDWR that 
includes an MCL or treatment technique, to publish and seek public 
comment on an analysis of health risk reduction and cost impacts. In 
addition, EPA is required to take into consideration the effects of 
contaminants upon sensitive subpopulations (i.e. infants, children, 
pregnant women, the elderly, and individuals with a history of serious 
illness), and other relevant factors. (Section 1412 (b)(3)(C)).
    The amendments established a number of regulatory deadlines, 
including schedules for a Stage 1 Disinfection Byproduct Rule (DBPR), 
an Interim Enhanced Surface Water Treatment Rule (IESWTR), a Long-Term 
Final Enhanced Surface Water Treatment Rule (LTESWTR) affecting Public 
Water Systems (PWSs) that serve under 10,000 people, and a Stage 2 DBPR 
(Section 1412(b)(2)(C)). The Act as amended also requires EPA to 
promulgate regulations to address filter backwash (Section 
1412(b)(14)). Finally, the Act requires EPA to promulgate regulations 
specifying criteria for requiring disinfection ``as necessary'' for 
ground water systems (Section 1412 (b)(8)).
    Finally, as part of the 1996 SDWA Amendments, recordkeeping 
requirements were modified to apply to ``every person who is subject to 
a requirement of this title or who is a grantee'' (Section 1445 
(a)(1)(A)). Such persons are required to ``establish and maintain such 
records, make such reports, conduct such monitoring, and provide such 
information as the Administrator may reasonably require by regulation * 
* * ''.

B. Regulatory History

1. Existing Regulations
    Surface Water Treatment Rule. Under the Surface Water Treatment 
Rule (SWTR) (54 FR 27486, June 29, 1989) (EPA,1989a), EPA set maximum 
contaminant level goals of zero for Giardia lamblia, viruses, and 
Legionella; and promulgated NPDWR for all PWSs 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 many other pathogenic organisms. Briefly, those requirements 
include: (1) requirements for a maintenance of a disinfectant residual 
in the distribution system; (2) removal and/or inactivation of 3 logs 
(99.9%) for Giardia and 4 logs (99.99%) for viruses; (3) combined 
filter effluent performance of 5 nephelometric turbidity unit (NTU) as 
a maximum and 0.5 NTU at 95th percentile monthly, based on 4-hour 
monitoring for treatment plants using conventional treatment or direct 
filtration (with separate standards for other filtration technologies); 
and (4) watershed protection and other requirements for unfiltered 
systems.
    Total Coliform Rule. The Total Coliform Rule (TCR) (54 FR 27544; 
June 29, 1989) applies to all public water systems (EPA, 1989b). This 
regulation sets compliance with the MCL for total coliforms (TC) as 
follows. For systems that collect 40 or more samples per month, no more 
than 5.0% of the samples may be TC-positive; for those that collect 
fewer than 40 samples, no more than one sample may be TC-positive. In 
addition, if two consecutive samples in the system are TC-positive, and 
one is also fecal coliform or E. coli-positive, then this is defined as 
an acute violation of the MCL. If a system exceeds the MCL, it must 
notify the public using mandatory language developed by the EPA. The 
required monitoring frequency for a system depends on the number of 
people served and, ranges from 480 samples per month for the largest 
systems to once annually for certain of the smallest systems. All 
systems must have a written plan identifying where samples are to be 
collected.
    If a system has a TC-positive sample, it must test that sample for 
the presence of fecal coliforms or E. coli. The system must also 
collect a set of repeat samples, and analyze for TC (and fecal coliform 
or E. coli) within 24 hours of the first TC-positive sample.
    The TCR also requires an on-site inspection every 5 years (10 years 
for non-community systems using only protected and disinfected ground 
water) for each system that collects fewer than five samples per month. 
This on-site inspection (referred to as a sanitary survey) must be 
performed by the State or by an agent approved by the State.
    Total Trihalomethane Rule. In November 1979 (44 FR 68624) (EPA, 
1979) EPA set an interim MCL for total trihalomethanes (TTHM) of 0.10 
milligrams per liter (mg/L) as an annual average. Compliance is defined 
on the basis of a running annual average of quarterly averages of all 
samples. The value for each sample is the sum of the measured 
concentrations of chloroform, bromodichloromethane (BDCM), 
dibromochloromethane (DBCM) and bromoform.
    The interim TTHM standard only applies to community water systems 
using surface water and/or ground water serving at least 10,000 people 
that add a disinfectant to the drinking water during any part of the 
treatment process. At their discretion, States may extend coverage to 
smaller PWSs; however, most States have not exercised this option.
    Information Collection Rule. The Information Collection Rule (ICR) 
is a monitoring and data reporting rule that was promulgated on May 14, 
1996 (61 FR 24354) (EPA, 1996a). The purpose of the ICR is to collect 
occurrence and treatment information to help evaluate the need for 
possible changes to the current SWTR and existing microbial treatment 
practices, and to help evaluate the need for future regulation for 
disinfectants and disinfection byproducts (D/DBPs). The ICR will 
provide EPA with additional information on the national occurrence in 
drinking water of (1) chemical byproducts that form when disinfectants 
used for microbial control react with naturally occurring compounds 
already present in source water and (2) disease-causing microorganisms, 
including Cryptosporidium, Giardia, and viruses. The ICR will also 
provide engineering data on how PWSs currently control for such 
contaminants. This information is being collected because the 1992 
Regulatory Negotiating Committee (henceforth referred to as the Reg. 
Neg. Committee) on microbial pathogens and disinfectants and DBPs 
concluded that additional information was needed to assess the 
potential health problem created by the presence of DBPs and pathogens 
in drinking water and to assess the extent and severity of risk in 
order to make sound regulatory and public health decisions. The ICR 
will also provide information to support regulatory impact analyses for 
various regulatory options, and to help develop monitoring strategies 
for cost-effectively implementing regulations.
    The ICR pertains to large public water systems serving populations 
at least 100,000; a more limited set of ICR requirements pertain to 
ground water systems serving between 50,000 and 100,000 people. About 
300 PWSs operating 500 treatment plants are involved with the extensive 
ICR data collection. Under the ICR, these PWSs monitor for water 
quality factors affecting DBP formation and DBPs

[[Page 69394]]

within the treatment plant and in the distribution system monthly for 
18 months. In addition, PWSs must provide operating data and a 
description of their treatment plan design and surface water systems 
must monitor for bacteria, viruses, and protozoa. Finally, a subset of 
PWSs must perform treatment studies, using either granular activated 
carbon (GAC) or membrane processes, to evaluate DBP precursor removal 
and control of DBPs. Monitoring for treatment study applicability began 
in September 1996. The remaining occurrence monitoring began in July 
1997.
    One initial intent of the ICR was to collect pathogen occurrence 
data and other information for use in developing the IESWTR and to 
estimate national costs for various treatment options. However, because 
of delays in promulgating the ICR and technical difficulties associated 
with laboratory approval and review of facility sampling plans, ICR 
monitoring did not begin until July 1, 1997, which was later than 
originally anticipated. As a result of this delay and the new statutory 
deadlines for promulgating the Stage 1 DBPR and IESWTR in November of 
1998 (resulting from the 1996 SDWA amendments), ICR data were not 
available in time to support these rules. In place of the ICR data, the 
Agency worked with stakeholders to identify other sources of data 
developed since 1994 that could be used to support the development of 
the Stage 1 DBPR and IESWTR. EPA will continue to work with 
stakeholders in analyzing and using the comprehensive ICR data and 
research for developing future Enhanced Surface Water Treatment 
requirements and the Stage 2 DBPR.
2. Public Health Concerns to be Addressed
    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.
    In regard to the Stage 1 DBPR, EPA recognizes that the assessment 
of public health risks from disinfection of drinking water currently 
relies on inherently difficult and preliminary empirical analysis. On 
one hand, epidemiologic studies of the populations in various 
geographic areas are hampered by difficulties of study design, scope, 
and sensitivity. On the other hand, uncertainty is involved in the 
interpretation of results using high dose animal toxicological studies 
of a few of the numerous byproducts that occur in disinfected drinking 
water to estimate the risk to humans from chronic exposure to low doses 
of these and other byproducts. Such studies of individual DBPs is 
insufficient to characterize risks from exposure to the entire mixture 
of DBPs in disinfected drinking water. While recognizing these 
uncertainties, EPA continues to believe that the Stage 1 DBPR is 
necessary for the protection of public health from exposure to 
potentially harmful DBPs.
    A fundamental component in assessing the risk for a contaminant is 
the number of people that may be exposed to the parameter of concern. 
In this case, there is a very large population potentially exposed to 
DBPs through drinking water in the U.S. Over 200 million people are 
served by PWSs that apply a disinfectant (e.g., chlorine) to water in 
order to provide protection against microbial contaminants. While these 
disinfectants are effective in controlling many microorganisms, they 
react with natural organic and inorganic matter in the water to form 
DBPs, some of which may pose health risks. One of the most complex 
questions facing water supply professionals is how to minimize the 
risks from DBPs and still maintain adequate control over microbial 
contaminants. Because of the large number of people exposed to DBPs, 
there is a substantial concern for any risks associated with DBPs that 
may impact public health.
    Since the discovery of chlorination byproducts in drinking water in 
1974, numerous toxicological studies have been conducted. Results from 
these studies have shown several DBPs (e.g., bromodichloromethane, 
bromoform, chloroform, dichloroacetic acid, and bromate) to be 
carcinogenic in laboratory animals . Some DBPs (e.g., chlorite, BDCM, 
and certain haloacetic acids) have also been shown to cause adverse 
reproductive or developmental effects in laboratory animals. Although 
many of these studies have been conducted at high doses, EPA believes 
the studies provide evidence that DBPs present a potential public 
health risk that needs to be addressed.
    In the area of epidemiology, a number of epidemiology 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, these studies have suggested an association, albeit small, 
between bladder, rectal, and colon cancer and exposure to chlorinated 
surface water. While there are fewer published epidemiology studies 
that have been conducted to evaluate the possible relationship between 
exposure to chlorinated surface water and reproductive and 
developmental effects, a recent study has suggested an association 
between early term miscarriage and exposure to drinking water with 
elevated trihalomethane levels. In addition to this study, another new 
study reported a small increased risk of neural tube defects associated 
with consumption of drinking water containing high levels of TTHMs. 
However, no significant associations were observed with individual 
THMs, HAAs, and haloacetonitriles (HANs) and adverse outcomes in this 
study. As with cancer, EPA cannot conclude at this time there is a 
causal link between exposure to DBPs and reproductive and developmental 
effects.
    While EPA recognizes there are data deficiencies in the information 
on the health effects from the DBPs and the levels at which they occur, 
the Agency believes the weight-of-evidence presented by the available 
epidemiological studies on chlorinated drinking water and toxicological 
studies on individual DBPs support a potential hazard concern and 
warrant regulatory action at this time to reduce DBP levels in drinking 
water. Recognizing the deficiencies in the existing data, EPA believes 
the incremental two-stage approach for regulating DBPs, agreed upon by 
the regulatory negotiation process, is prudent and necessary to protect 
public health and meet the requirements of the SDWA.
    In conclusion, because of the large number of people exposed to 
DBPs and the different potential health risks (e.g., cancer and adverse 
reproductive and developmental effects) that may result from exposure 
to DBPs, EPA believes the Stage 1 DBPR is needed to further prevent 
potential health effects from DBPs, beyond that controlled for by the 
1979 total trihalomethane rule. Both the Reg. Neg. Committee for the 
1994 proposed rule and the Microbial and Disinfectants/Disinfection 
Byproducts Advisory Committee (henceforth cited as the M-DBP Advisory 
Committee) formed in March 1997 under the Federal Advisory Committee 
Act (FACA), agreed with the need for the Stage 1 DBPR to reduce 
potential risks from DBPs in the near term, while acknowledging 
additional information is still needed for the Stage 2 DBPR (especially 
on health effects),

[[Page 69395]]

3. Regulatory Negotiation Process
    In 1992 EPA initiated a negotiated rulemaking to address public 
health concerns associated with disinfectants, DBPs, and microbial 
pathogens. The negotiators included representatives of State and local 
health and regulatory agencies, public water systems, elected 
officials, consumer groups and environmental groups. The Reg. Neg. 
Committee met from November 1992 through June 1993.
    Early in the process, the negotiators agreed that large amounts of 
information necessary to understand how to optimize the use of 
disinfectants to concurrently minimize microbial and DBP risk on a 
plant-specific basis were unavailable. Nevertheless, the Reg. Neg. 
Committee agreed that EPA propose a Stage 1 DBPR to extend coverage to 
all community and nontransient noncommunity water systems that use 
disinfectants, reduce the current TTHM MCL, regulate additional DBPs, 
set limits for the use of disinfectants, and reduce the level of 
organic precursor compounds in the source water that may react with 
disinfectants to form DBPs.
    EPA's most significant concern in developing regulations for 
disinfectants and DBPs was the need to ensure that adequate treatment 
be maintained for controlling risks from microbial pathogens. One of 
the major goals addressed by the Reg. Neg. Committee was to develop an 
approach that would reduce the level of exposure from disinfectants and 
DBPs without undermining the control of microbial pathogens. The 
intention was to ensure that drinking water is microbiologically safe 
at the limits set for disinfectants and DBPs and that these chemicals 
do not pose an unacceptable health risk at these limits. Thus, the Reg. 
Neg. Committee also considered a range of microbial issues and agreed 
that EPA should also propose a companion microbial rule (IESWTR).
    Following months of intensive discussions and technical analysis, 
the Reg. Neg. Committee recommended the development of three sets of 
rules: a two-staged approach for the DBPs (proposal: 59 FR 38668, July 
29, 1994) (EPA, 1994a), an ``interim'' ESWTR (proposal: 59 FR 38832, 
July 29, 1994) (EPA, 1994b), and an information collection rule 
(proposal: 59 FR 6332, February 10, 1994) (EPA, 1994c) (promulgation: 
61FR24354, May 14, 1996) (EPA, 1996a). The approach used in developing 
these proposals considered the constraints of simultaneously treating 
water to control for both microbial contaminants and D/DBPs.
    The Reg. Neg. Committee agreed that the schedules for IESWTR and 
LTESWTR should be ``linked'' to the schedule for the Stage 1 DBPR to 
assure simultaneous compliance and a balanced risk-risk based 
implementation. The Reg. Neg. Committee agreed that additional 
information on health risk, occurrence, treatment technologies, and 
analytical methods needed to be developed in order to better understand 
the risk-risk tradeoff, and how to accomplish an overall reduction in 
health risks to both pathogens and D/DBPs.
    Finally the Reg. Neg. Committee agreed that to develop a reasonable 
set of rules and to understand more fully the limitations of the 
current SWTR, additional field data were critical. Thus, a key 
component of the regulation negotiation agreement was the promulgation 
of the ICR previously described.
4. Federal Advisory Committee Process
    In May 1996, the Agency initiated a series of public informational 
meetings to provide an update on the status of the 1994 proposal and to 
review new data related to microbial and DBP regulations that had been 
developed since July 1994. In August 1996, Congress enacted the 1996 
SDWA Amendments which contained a number of new requirements, as 
discussed above, as well as specifying deadlines for final promulgation 
of the IESWTR and Stage 1 DBPR. To meet these deadlines and to maximize 
stakeholder participation, the Agency established the M-DBP Advisory 
Committee under FACA in March 1997, to collect, share, and analyze new 
information and data, as well as to build consensus on the regulatory 
implications of this new information. The 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 M-DBP Advisory Committee met five times in March through July 
1997 to discuss issues related to the IESWTR and Stage 1 DBPR. 
Technical support for these discussions was provided by a Technical 
Work Group (TWG) established by the Committee at its first meeting in 
March 1997. The Committee's activities resulted in the collection, 
development, evaluation, and presentation of substantial new data and 
information related to key elements of both proposed rules. The 
Committee reached agreement on a number of major issues that were 
discussed in Notices of Data Availability (NODA) for the IESWTR (62 FR 
59486, November 3, 1997) (EPA, 1997a) and the Stage 1 DBPR (62 FR 
59388, November 3, 1997) (EPA, 1997b). The major recommendations 
addressed by the Committee and in the NODAs were to: (1) Maintain the 
proposed MCLs for TTHM, HAA5, and bromate; (2) modify the enhanced 
coagulation requirements as part of DBP control; (3) include a 
microbial benchmarking/profiling to provide a methodology and process 
by which a PWS and the State, working together, assure that there will 
be no significant reduction in microbial protection as the result of 
modifying disinfection practices in order to meet MCLs for TTHM and 
HAA5; (4) continue credit for compliance with applicable disinfection 
requirements for disinfection applied at any point prior to the first 
customer, consistent with the existing SWTR; (5) modify the turbidity 
performance requirements and add requirements for individual filters; 
(6) establish an MCLG for Cryptosporidium; (7) add requirements for 
removal of Cryptosporidium; (8) provide for mandatory sanitary surveys; 
and (9) make a commitment to additional analysis of the role of 
Cryptosporidium inactivation as part of a multiple barrier concept in 
the context of a subsequent Federal Register microbial proposal. The 
new data and analysis supporting the technical areas of agreement were 
summarized and explained at length in EPA's 1997 NODAs (EPA, 1997a and 
EPA, 1997b).
5. 1997 and 1998 Notices of Data Availability
    In November 1997 EPA published a NODA (USEPA, 1997b) that 
summarized the 1994 proposal; described new data and information that 
the Agency has obtained and analyses that have been developed since the 
proposal; provided information concerning the July 1997 recommendations 
of the M-DBP Advisory Committee on key issues related to the proposal 
(described above); and requested comment on these recommendations, as 
well as on other regulatory implications that flow from the new data 
and information. The Agency solicited additional data and information 
that were relevant to the issues discussed in the DBP NODA. EPA also 
requested that any information the Agency should consider as part of 
the final rule development process regarding data or views submitted to 
the Agency since the close of the comment period on the 1994 proposal, 
be formally resubmitted during the 90-day

[[Page 69396]]

comment period unless already in the underlying record in the docket 
for the NODA.
    In March 1998, EPA issued a second DBP NODA (EPA, 1998a) that 
summarized new health effects information received and analyzed since 
the November 1997 NODA and requested comments on several issues related 
to the simultaneous compliance with the Stage 1 DBPR and the Lead and 
Copper Rule. The 1998 NODA indicated EPA was considering increasing the 
MCLG for chloroform from zero to 0.3 mg/L and the proposed MCLG for 
chlorite from 0.08 mg/L to 0.8 mg/L. EPA also requested comment on 
increasing the Maximum Residual Disinfection Level Goal (MRDLG) for 
chlorine dioxide from 0.3 mg/L to 0.8 mg/L. Today's final rule was 
developed based on the outcome of the 1992 Reg. Neg., the 1994 proposed 
rule, the 1997 FACA process, and both the 1997 and 1998 DBP NODAs, as 
well as a wide range of technical comments from stakeholders and 
members of the public. A summary of today's rule follows.

II. Summary of Final Stage 1 Disinfection Byproduct Rule

A. Applicability

    The final Stage 1 DBPR applies to community water systems (CWSs) 
and nontransient noncommunity water systems (NTNCWs) that treat their 
water with a chemical disinfectant for either primary or residual 
treatment. In addition, certain requirements for chlorine dioxide apply 
to transient noncommunity water systems (TNCWSs).

B. MRDLGs and MRDLs for Disinfectants

    EPA is finalizing the following MRDLGs and maximum residual 
disinfectant levels (MRDLs) for chlorine, chloramines, and chlorine 
dioxide in Table II-1.

                                 Table II-1.--MRDLGs and MRDLs for Disinfectants
----------------------------------------------------------------------------------------------------------------
          Disinfectant residual                      MRDLG (mg/L)                         MRDL (mg/L)
----------------------------------------------------------------------------------------------------------------
Chlorine................................  4 (as Cl2)                          4.0 (as Cl2)
Chloramine..............................  4 (as Cl2)                          4.0 (as Cl2)
Chlorine Dioxide........................  0.8 (as ClO2)                       0.8 (as ClO2)
----------------------------------------------------------------------------------------------------------------

C. MCLGs and MCLs for TTHMs, HAA5, Chlorite, and Bromate

    EPA is finalizing the MCLGs and MCLs in Table II-2.

         Table II-2.--MCLGs and MCLs for Disinfection Byproducts
------------------------------------------------------------------------
           Disinfection byproducts             MCLG (mg/L)   MCL (mg/L)
------------------------------------------------------------------------
Total trihalomethanes (TTHM) \1\............        N/A            0.080
    --Chloroform............................          0     ............
    --Bromodichloromethane..................          0     ............
    --Dibromochloromethane..................          0.06  ............
    --Bromoform.............................          0     ............
Haloacetic acids (five) (HAA5) \2\..........        N/A            0.060
    --Dichloroacetic acid...................          0     ............
    --Trichloroacetic acid..................          0.3   ............
Chlorite....................................          0.8          1.0
Bromate.....................................          0            0.010
------------------------------------------------------------------------
N/A--Not applicable because there are no individual MCLGs for TTHMs or
  HAAs.
\1\ Total trihalomethanes is the sum of the concentrations of
  chloroform, bromodichloromethane, dibromochloromethane, and bromoform.
\2\ Haloacetic acids (five) is the sum of the concentrations of mono-,
  di-, and trichloroacetic acids and mono- and dibromoacetic acids.

D. Treatment Technique for Disinfection Byproduct Precursors

    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) that may react with 
disinfectants to form DBPs as indicated in Table II-3. Removal will be 
achieved through a treatment technique (enhanced coagulation or 
enhanced softening) unless a system meets alternative criteria 
discussed in Section III.D.

    Table II-3.--Required Removal of Total Organic Carbon by Enhanced
     Coagulation and Enhanced Softening for Subpart H Systems Using
                     Conventional Treatment a,\b,\c
------------------------------------------------------------------------
                                      Source Water Alkalinity (mg/L as
                                              CaCO3) (percent)
     Source Water TOC (mg/L)      --------------------------------------
                                       0-60       >60-120        >120
------------------------------------------------------------------------
>2.0-4.0.........................         35.0         25.0         15.0
>4.0-8.0.........................         45.0         35.0         25.0

[[Page 69397]]

 
>8.0.............................         50.0         40.0         30.0
------------------------------------------------------------------------
a Systems meeting at least one of the conditions in Section
  141.135(a)(2) (i)-(vi) of the rule are not required to operate the
  removals in this table.
b Softening systems meeting one of the two alternative compliance
  criteria in Section 141.135(a)(3) of the rule are not required to meet
  the removals in this table.
c Systems practicing softening must meet the TOC removal requirements in
  the last column to the right.

E. BAT for Disinfectants, TTHMs, HAA5, Chlorite, and Bromate

    Under the SDWA, EPA must specify the BAT for each MCL (or MRDL) 
that is set. PWS that are unable to achieve an MCL or MRDL may be 
granted a variance if they use the BAT and meet other requirements (see 
section III.M for a discussion of variances and exemptions). Table II.4 
includes the BATs for each of the MCLs or MRDLs that EPA is 
promulgating in today's Stage 1 DBPR.

     Table II-4.--BAT for Disinfectants and Disinfection Byproducts
------------------------------------------------------------------------
       Disinfectant/DBP                Best available technology
------------------------------------------------------------------------
                              Disinfectants
 
------------------------------------------------------------------------
Chlorine residual............  Control of treatment processes to reduce
                                disinfectant demand and control of
                                disinfection treatment processes to
                                reduce disinfectant levels.
Chloramine residual..........  Control of treatment processes to reduce
                                disinfectant demand and control of
                                disinfection treatment processes to
                                reduce disinfectant levels.
Chlorine dioxide residual....  Control of treatment processes to reduce
                                disinfectant demand and control of
                                disinfection treatment processes to
                                reduce disinfectant levels.
 
------------------------------------------------------------------------
                         Disinfection Byproducts
 
------------------------------------------------------------------------
Total trihalomethanes........  Enhanced coagulation or enhanced
                                softening or GAC10*, with chlorine as
                                the primary and residual disinfectant.
Total haloacetic acids.......  Enhanced coagulation or enhanced
                                softening or GAC10*, with chlorine as
                                the primary and residual disinfectant.
Chlorite.....................  Control of treatment processes to reduce
                                disinfectant demand and control of
                                disinfection treatment processes to
                                reduce disinfectant levels.
Bromate......................  Control of ozone treatment process to
                                reduce production of bromate.
------------------------------------------------------------------------
* GAC10 means granular activated carbon with an empty bed contact time
  of 10 minutes and reactivation frequency for GAC of no more than six
  months.

F. Compliance Monitoring Requirements

    Compliance monitoring requirements are explained in Section III.H 
of today's rule. EPA has developed routine and reduced compliance 
monitoring schemes for disinfectants and DBPs to be protective from 
different types of health concerns, including acute and long-term 
effects.

G. Analytical Methods

    EPA has approved five methods for measurement of free chlorine, 
four methods for combined chlorine, and six for total chlorine. EPA has 
also approved two methods for the measurement of chlorine dioxide 
residuals; three methods for the measurement of HAA5; three methods for 
the measurement of TTHMs; three methods for the measurement of TOC/
Dissolved Organic Carbon (DOC); two methods for the monthly measurement 
of chlorite and one method for the daily monitoring of chlorite; two 
methods for bromide; one method for the measurement of bromate; and one 
method for the measurement of UV254. Finally, EPA approved 
all methods allowed in Sec. 141.89(a) for measuring alkalinity. These 
issues are discussed in more detail in section III.G.

H. Laboratory Certification Criteria

    Consistent with other drinking water regulations, determinations of 
compliance with the MCLs may only be conducted by certified 
laboratories. EPA is requiring that analyses can be conducted by a 
party acceptable to EPA or the State in those situations where the 
parameter can adequately be measured by someone other than a certified 
laboratory and for which there is a good reason to allow analysis at 
other locations (e.g., for samples which normally deteriorate before 
reaching a certified laboratory, especially when taken at remote 
locations). For a detailed discussion of the lab certification 
requirements, see section III.N.

I. Variances and Exemptions

    Variances and exemptions will be permitted in accordance with 
existing statutory and regulatory authority. For a detailed discussion 
see section III.M.

J. State Recordkeeping, Primacy, and Reporting Requirements

    The Stage 1 DBPR requires States to adopt several regulatory 
requirements, including public notification requirements, MCLs for 
DBPs, MRDLs for disinfectants, and the requirements in Subpart L. In 
addition, States are required to adopt several special primacy 
requirements for the Stage 1 DPBR. States are also required to keep 
specific records in accordance with existing regulations and additional 
records specific to the Stage 1 DBPR. Finally, the rule does not 
require any

[[Page 69398]]

State additional reporting requirements beyond those required under 
existing regulations. These requirements are discussed in more detail 
in Section III.L.

K. System Reporting Requirements

    System are required to report monitoring data to the State as 
discussed in Section III.K.

L. Guidance Manuals

    EPA is developing guidance for both systems and States for the 
implementation of the Stage 1 DBPR and the IESWTR. The guidance manuals 
include: Guidance Manual for Enhanced Coagulation and Precipitative 
Softening; Disinfection Benchmark Guidance Manual; Turbidity Guidance 
Manual; Alternative Disinfectants and Oxidants Guidance Manual; M/DBP 
Simultaneous Compliance Manual; Sanitary Survey Guidance Manual; 
Unfiltered Systems Guidance Manual; and Uncovered Finished Water 
Reservoirs. Guidance manuals will be available after the publication of 
the Stage 1 DBPR.

M. Regulation Review

    Under the provisions of the SDWA (Section 1412(b)(9)), the Agency 
is required to review NPDWRs at least once every six years. As 
mentioned previously, today's final rule revises, updates, and 
supersedes the regulations for total trihalomethanes, initially 
published in 1979. Since that time, there have been significant changes 
in technology, treatment techniques, and other regulatory controls that 
provide for greater protection of human health. As such, for today's 
rule, EPA has analyzed innovations and changes in technology and 
treatment techniques that have occurred since promulgation of the 
interim TTHM regulations. That analysis, contained primarily in the 
cost and technology document supporting this rule, supports the changes 
in the Stage 1 DBPR from the 1979 TTHM rule. EPA believes that the 
innovations and changes in technology and treatment techniques that 
result in changes to the 1979 TTHM regulations are feasible within the 
meaning of SDWA Section 1412(b).

III. Explanation of Final Rule

A. MCLGs/MRDLGs

    MCLGs are set at levels at which no known or anticipated adverse 
health effects occur, allowing for an adequate margin of safety. 
Establishment of an MCLG for each specific contaminant is based on the 
available evidence of carcinogenicity or noncancer adverse health 
effects from drinking water exposure using EPA's guidelines for risk 
assessment (see the proposed rule at 59 FR 38677 for a detailed 
discussion of the process for establishing MCLGs).
    The final Stage 1 DBPR contains MCLGs for: four THMs (chloroform, 
bromodichloromethane, dibromochloromethane, and bromoform); two 
haloacetic acids (dichloroacetic acid and trichloroacetic acid); 
bromate; and chlorite (see table II-2 for final MCLG levels). These 
MCLGs are the same as those proposed in 1994 with the exception of 
chlorite, which increased from 0.08 mg/L to 0.8 mg/L. The MCLG for 
chloral hydrate has been dropped since EPA has concluded that it will 
be controlled by the MCLs for TTHM and HAA5 and the enhanced 
coagulation treatment technique.
    The final Stage 1 DBPR contains MRDLGs for chlorine, chloramines 
and chlorine dioxide (see table II-1 for final MRDLG levels). The 
MRDLGs are as the same as those proposed in 1994, with the exception of 
chlorine dioxide, which increased from 0.3 mg/L to 0.8 mg/L.
    The MRDLG concept was introduced in the proposed rule for 
disinfectants to reflect the fact that these substances have beneficial 
disinfection properties. As with MCLGs, MRDLGs are established at the 
level at which no known or anticipated adverse effects on the health of 
persons occur and which allows an adequate margin of safety. MRDLGs are 
nonenforceable health goals based only on health effects and exposure 
information and do not reflect the benefit of the addition of the 
chemical for control for waterborne microbial contaminants. By using 
the term ``residual disinfectant'' in lieu of ``contaminant'', EPA 
intends to avoid situations in which treatment plant operators are 
reluctant to apply disinfectant dosages above the MRDLG during short 
periods of time to control for microbial risk.
    EPA received numerous comments on the use of the term MRDLG. The 
majority of commenters agreed that the term MRDLG was appropriate to 
use in place of MCLG for disinfectants. Other commenters agreed, but 
felt that the language should more strongly reflect that disinfectants 
are necessary and that short-term exposure to elevated levels of the 
disinfectants is not a health concern. Some commenters suggested that 
MRDLGs be extended to ozone, potassium permanganate and iodine.
    In response, EPA agrees with the majority of commenters that the 
use of the term MRDLG is appropriate and therefore the final rule 
retains this term. EPA believes the language on the importance of 
disinfectants is adequate in the rule and thus has not changed this 
language. EPA does not agree that the potential health effects from 
short-term exposure to elevated levels of disinfectants can be 
dismissed. Ozone does not require an MRDLG because it reacts so 
completely that it does not occur in water delivered to consumers. 
Finally, EPA believes the use of the MRDLGs for other disinfectants or 
oxidants would not be appropriate since MRDLGs are developed for 
regulated compounds controlled by MRDLs or treatment techniques and EPA 
does not allow these compounds to be used to demonstrate compliance 
with disinfection requirements.
    The information EPA relied on to establish the MCLGs and MRDLGs was 
described in the 1994 proposal (EPA, 1994a), the 1997 DBP NODA (EPA, 
1997b), and the 1998 NODA (EPA, 1998a). Criteria and assessment 
documents to support the MCLGs and MRDLGs are included in the docket 
(EPA, 1993a; EPA, 1994 d-h; EPA, 1997c; EPA, 1998 b-f; and EPA, 1998p). 
A summary of the occurrence and exposure information for this rule are 
detailed in ``Occurrence Assessment for Disinfectants and Disinfection 
Byproducts in Public Drinking Water Supplies' (EPA, 1998u). The 
discussion of the data used to establish the MCLGs and MRDLGs and a 
summary of the major public comments for these chemicals are included 
below. A more detailed discussion is included below for chloroform, 
DCA, chlorite, chloride dioxide, and bromate than the other 
disinfectants and DBPs. This is the case because significant new data 
has become available since the 1994 proposal for these four DBPs and 
one disinfectant.
1. MCLG for Chloroform
    a. Today's Rule. After careful consideration of all public 
comments, EPA has concluded at this time to promulgate an MCLG for 
chloroform of zero as proposed. This conclusion reflects an interim 
risk-management decision on the part of the Agency. The Agency 
recognizes the strength of the science in support of a non-linear 
approach for estimating carcinogenicity of chloroform. EPA received 
public comments that questioned the underlying basis and approach used 
to reach the science judgment that the mode of chloroform's 
carcinogenic action supports a nonlinear approach. Equally important 
are the policy and regulatory issues raised by stakeholders that touch 
on this issue. EPA believes that it is essential to pursue a further 
dialogue with stakeholders on the issues raised in the public comments 
before applying the substantial new data and science on the mode of 
carcinogenic

[[Page 69399]]

action discussed in the 1998 NODA to the important decision of moving 
to a non-linear cancer extrapolation approach for drinking water 
contaminants under the SDWA. Moreover, EPA will complete additional 
deliberations with the Agency's Science Advisory Board (SAB) (open to 
stakeholder presentations to the SAB) on the analytical approach used 
to evaluate and reach conclusions on mode of action data, and the 
science basis for the mode of carcinogenic action for chloroform.
    In evaluating how to proceed in the development of an MCLG for 
chloroform, the Agency believes two additional factors must be taken 
into consideration. First, as part of the 1996 SDWA amendments, 
Congress mandated that the Stage 1 DBPR rule be promulgated by November 
1998. EPA has concluded that it would be impossible to complete the 
additional deliberations noted above in time to meet this statutory 
deadline. Second, as explained below, the Agency has also completed 
analysis indicating that regardless of whether the MCLG is based on a 
low-dose linear or non-linear extrapolation approach, the MCL 
enforceable standard for TTHMs of 0.08 mg/L will not be affected. In 
light of these issues, EPA believes it is appropriate and consistent 
with the public health goals of the SDWA to establish a zero MCLG for 
chloroform based on a linear default extrapolation approach until the 
Agency is able to complete additional deliberations with the Agency's 
SAB on the analytical approach used to evaluate and reach conclusions 
on mode of action data and the science basis for the mode of 
carcinogenic action for chloroform, and complete the process of further 
public dialogue on the important question of moving to a non-linear 
cancer extrapolation approach. EPA also notes that its approach is 
consistent with legislative history of the SDWA (see 56 FR 3533--EPA, 
1991) and the 1996 SDWA Amendments.
    b. Background and Analysis. As part of its 1994 Stage 1 DBP 
proposal (EPA, 1994a), EPA requested comment on a zero MCLG for 
chloroform. This was consistent with information provided to the 1992 
Reg. Neg. Committee and was based on data from a drinking water study 
by Jorgensen et al. (1985) indicating an increase of kidney tumors in 
male rats in a dose-related manner. However, at the time of the 
proposal there was insufficient data to determine the mode of 
carcinogenic action for chloroform. Therefore, EPA based its 1994 
proposal on a risk management decision that a presumptive or low-dose 
linear default (i.e, MCLG of zero) was appropriate until more research 
became available and there was an adequate opportunity to work with 
stakeholders and the scientific community to evaluate and assess the 
technical as well as policy and regulatory implications of such new 
information. The 1994 proposal also reflected the Agency's 1986 
Guidelines for Carcinogen Risk Assessment (EPA, 1986) which recommended 
reliance on the default assumption of low-dose linearity in the absence 
of substantial information on the mechanism of carcinogenicity.
    Since the 1994 proposal, over 30 toxicological studies have been 
published on chloroform. These studies were discussed in the November 
1997 Stage 1 DBP NODA (EPA, 1997b). In addition, EPA published a second 
DBP NODA in March 1998 (EPA, 1998a) which discussed recommendations and 
findings from a 1997 International Life Sciences Institute project 
(ILSI, 1997), co-sponsored by EPA, on the cancer assessment for 
chloroform. The ILSI project included the analysis and conclusions from 
an expert panel which was convened and charged with reviewing the 
available database relevant to the carcinogenicity of chloroform, and 
considering how end points related to mode of action can be applied in 
hazard and dose-response assessment by using guidance provided by the 
EPA's 1996 Proposed Guidelines for Carcinogen Assessment (EPA, 1996b). 
The panel was made up of 10 internationally recognized scientists from 
academia, industry, government, and the private sector. Based on a 
consideration of the ILSI panel findings and an assessment of new data 
on chloroform since 1994, EPA requested comment in the 1998 NODA on the 
Agency's science conclusion that chloroform is a likely human 
carcinogen and that available scientific analysis supports a non-linear 
mode of action for estimating the carcinogenic risk associated with 
lifetime exposure from ingesting drinking water.
    As part of the 1998 NODA, EPA also requested comment on a revised 
chloroform MCLG of 0.30 mg/L. The revised MCLG was premised on the 
substantial new science noted above that supports a non-linear mode of 
action. In calculating the specific MCLG, EPA relied upon data relating 
to hepatoxicity in dogs (EPA, 1994a). This hepatoxicity endpoint was 
deemed appropriate given that hepatic injury is the primary effect 
following chloroform exposure; and that an MCLG based on protection 
against liver toxicity should be protective against carcinogenicity 
given that the putative mode of action understanding for chloroform 
involves cytotoxicity as a key event preceding tumor development. The 
MCLG of 0.3 mg/L was calculated using a relative source contribution 
(RSC) of 80 percent. The RSC of 80 percent was based on the assumption 
that most exposure to chloroform is likely to come from ingestion of 
drinking water. The 80 percent assumption for the RSC was consistent 
with the calculations used to derive the MCLGs for D/DBPs in the 1994 
proposal. Based on information received during the public comment 
period for the 1998 NODA, EPA is considering revising its estimate of 
the RSC for chloroform as discussed below.
    Since the 1998 NODA, EPA has reevaluated elements of the analysis 
underlying a revised MCLG of 0.30 mg/L. Considering recent information 
not fully analyzed as part of the 1998 NODA, the Agency is considering 
revising the assumption of an 80% RSC from ingestion of drinking water 
in view of data which indicates that exposure to chloroform via 
inhalation and dermal exposure may potentially contribute a substantial 
percentage of the overall exposure to chloroform depending on the 
activity patterns of individuals. Also, EPA is in the process of 
developing a policy for incorporating inhalation and dermal exposure 
into the derivation of the RSC. Furthermore, there is considerable 
uncertainty regarding the potential exposure to chloroform via the 
dietary route and there is information which indicates individuals who 
are frequent swimmers may receive a large amount of chloroform during 
swimming. There are additional uncertainties regarding other possible 
highly exposed sub-populations, e.g., from use of humidifiers, hot-
tubs, and outdoor misters. In conclusion, because there may be a 
potential for exposure to chloroform from other routes of exposure than 
ingestion of drinking water, EPA is considering using the 20 percent 
default floor to ensure adequate public health protection. The 20 
percent has been used historically for drinking water contaminants 
other than D/DBPs when there is uncertainty in the available exposure 
data. The use of the 20 percent RSC for chloroform would produce a MCLG 
of 0.07 mg/L:

[[Page 69400]]

[GRAPHIC] [TIFF OMITTED] TR16DE98.000


    In addition to its reassessment of technical assumptions underlying 
the revised MCLG, the Agency has also reviewed and carefully considered 
in detail a number of significant comments on the 1998 NODA. These 
comments reflect both substantial scientific support as well as 
significant concerns with a possible MCLG of 0.30 mg/L. As outlined in 
more detail below, a number of nationally recognized scientific experts 
strongly affirmed the data and technical rationale for relying upon a 
non-linear mode of action for chloroform. Other commenters, however, 
highlighted several scientific issues they felt were not adequately 
considered. These commenters also emphasized their concern that the 
policy, regulatory, and enforcement implications related to a revised 
MCLG were not raised by EPA in either the 1992 or the 1997 regulatory 
negotiation processes leading up to today's final rule. Thus, these 
commenters felt that a number of stakeholders who recommended support 
for components of the Stage 1 DBPR rule did so under one set of 
conditions and assumptions that the Agency subsequently changed without 
providing a sufficient opportunity for further debate and discussion.
    EPA believes that an adequate opportunity for notice and comment 
was provided as a result of the 1997 and 1998 DBP NODAs on the 
underlying scientific data and technical issue of moving to a non-
linear extrapolation approach based on an understanding of the mode of 
carcinogenic action for chloroform and recalculating the chloroform 
MCLG to a nonzero number. However, the Agency recognizes that reliance 
on a non-linear mode of action under the SDWA does represent a 
significant and precedential, albeit sound, application of new science 
to the policy development and risk management decision making process 
of establishing appropriately protective MCLGs. The Agency also 
recognizes that although, as discussed below, a revised MCLG for 
chloroform would not affect the TTHM MCL under today's rule, the 
precedential decision to utilize a non-linear cancer extrapolation 
approach clearly has important implications for the development of 
future MCLGs where there is also adequate scientific research and data 
to support such a non-linear analysis.
    In reviewing the range of scientific, policy, and regulatory 
analyses and strongly held views associated with development of the 
chloroform MCLG, EPA notes that the one question not fundamentally at 
issue is the establishment of the 0.080 mg/L TTHM MCL. The majority of 
commenters who addressed the proposed TTHM MCL continue to support it. 
This is particularly important to EPA in light of congressional action 
with regard to the M-DBP process in the 1996 SDWA Amendments. In 
enacting the Amendments and particularly in expressing congressional 
intent in the conference Report, Congress was careful to emphasize 
``that the new provisions of this conference agreement not conflict 
with the parties' agreement nor disrupt the implementation of the 
regulatory actions,'' (such as the current agreement on an TTHM MCL of 
0.080 mg/L). Both of these important elements of the Congressional 
intent were reflected in the statutory text. Section 1412(b)(2)(C) 
requires EPA to maintain the M-DBP rule staggered promulgation strategy 
agreed to by the negotiated rulemaking; and Section 1412(b)(6)(C) 
exempted the future M-DBP rules from the new cost-benefit standard-
setting provision (1412(b)(6)(A)) but not from the new risk-risk 
provision (1412(b)(5)), because the latter was a part of the negotiated 
rulemaking agreement but the former was not.
    The Agency, itself, also believes that the underlying logic, data, 
and rationale supporting establishment of a TTHM of 0.080 mg/L MCL is 
compelling, and this is a critical factor in the Agency's chloroform 
MCLG decision under today's rule. Under either a low-dose linear or 
non-linear extrapolation to derive the MCLG, the final TTHM MCL remains 
unaffected.
    After thorough review of the data and comments, EPA believes the 
nonlinear cancer extrapolation approach is the most appropriate means 
to establish an MCLG for chloroform based on carcinogenic risk. 
However, in light of its own reconsideration of the appropriate RSC for 
chloroform under such an approach, considering the range of policy, 
regulatory, and enforcement issues raised as part of the public comment 
period, recognizing the importance of deliberations with SAB before 
proceeding further and, yet, recognizing that this cannot be 
accomplished within the constraints of meeting the statutory deadline 
for Stage 1 DBPR rule of November 1998, EPA has determined that on 
balance the more appropriate and prudent risk management decision at 
this time is to establish an MCLG for chloroform at the proposed 
presumptive default level of zero. As part of this decision, the Agency 
will complete additional deliberations with the Agency's SAB on the 
analytical approach used to evaluate and reach conclusions on mode of 
action data, and the science basis for the mode of carcinogenic action 
for chloroform. The SAB's review will be factored into the Agency's 
Stage 2 DBP rulemaking process. EPA will also include consideration of 
the regulatory, policy, and precedential issues involving chloroform in 
the Agency's Round 2 M-BP stakeholder process. EPA wishes to make clear 
that its interim decision in today's rule to set an MCLG of zero 
pending SAB review and further stakeholder involvement is not intended 
to prejudge the question of what the appropriate MCLG should be for 
purposes of regulatory decisions under the Stage 2 DBPR. EPA may decide 
to retain the zero MCLG for that rule, or to revise it, depending on 
the outcome of the SAB review, as well as any new scientific evidence 
that may become available. In regard to the appropriate RSC factor, in 
case a non-linear approach should ultimately be adopted, the Agency 
requests that stakeholders provide any data they man have bearing on 
this determination.
    The fundamental objective of the SDWA is to establish protective 
public health goals (MCLGs) together with enforceable standards (MCLs 
or treatment techniques) to move the water treatment systems as close 
to the public health goal as is technologically and economically 
feasible. In the case of the chloroform and TTHMs, this objective is 
met with whichever extrapolation approach (low dose linear versus 
nonlinear) is relied upon.
    c. Summary of Comments. EPA received numerous comments on both the 
1994 proposed rule regarding the MCLG of zero for chloroform and the 
MCLG of 0.3 mg/L contained in the 1998 NODA. Some commenters were 
supportive of the MCLG of zero, while others were supportive of the 0.3 
mg/L MCLG. The major reason raised by commenters for establishing a 
nonzero MCLG (e.g., 0.3 mg/L) was that there was convincing scientific 
evidence to conclude that a nonlinear margin of exposure approach for 
evaluating the carcinogenic risk from chloroform is warranted. 
Commenters who were

[[Page 69401]]

against establishing a nonzero MCLG for chloroform presented policy and 
scientific concerns. Scientific concerns raised by commenters opposed 
to the nonzero MCLG included their perceptions that: there is 
insufficient scientific evidence of a threshold for chloroform; the 
threshold assumption is also invalid because chloroform co-occurs with 
other mutagenic carcinogens; EPA ignored human data in establishing the 
MCLG for chloroform; the linkage between cytotoxicity and regenerative 
proliferation and kidney tumors is not supported by the data; and the 
evidence for genotoxicity is mixed and it would be difficult if not 
impossible to conclude that the evidence demonstrate chloroform has no 
direct effect on DNA. As detailed at greater length in the docket, EPA 
does not agree with these comments as a technical matter. The Agency 
does agree with the commenters view that further discussion of these 
issues with both the SAB and as part of additional public dialogue is 
appropriate.
    The policy issues raised by commenters included their belief that: 
a zero MCLG is required to comply with provisions of the SDWA; EPA is 
required to use the 1986 Cancer Guidelines (EPA, 1986) until the 1996 
Cancer Guidelines (EPA, 1996b) are formally finalized, and under the 
1986 guidelines the MCLG for chloroform must be set at zero; EPA did 
not provide sufficient opportunity for the members of the FACA, 
established to assist in the development of the Stage 1 DBP rule, to 
properly consider the potential implications of a nonzero MCLG; and 
setting a MCLG for chloroform (0.3 mg/L) above the MCL for the TTHMs 
(0.08 mg/L) is illogical.
    In response, EPA believes that the underlying science for using a 
nonlinear extrapolation approach to evaluate the carcinogenic risk from 
chloroform is well founded. As explained above, because of the issues 
raised during the public comment period, EPA believes additional review 
and dialogue with stakeholders is needed prior to departing from a 
long-held EPA policy of establishing zero MCLGs for known or probable 
carcinogens. EPA will also complete additional deliberations with the 
Agency's SAB on the analytical approach used to evaluate and reach 
conclusions on mode of action data, and the science basis for the mode 
of carcinogenic action for chloroform.
    In response to the policy issues raised by commenters, EPA, 
historically, has 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 and therefore an MCLG above 
zero did not meet the statutory requirement that the goal be set where 
no known anticipated adverse effects occur, allowing for an adequate 
margin of safety (56 FR 3533; EPA, 1991). However, if there is 
scientific evidence that indicates there is a ``safe threshold'' then a 
non-zero MCLG could be established with an adequate margin of safety 
(56 FR 3533; EPA, 1991)). Even though EPA, as an interim matter, is 
establishing an MCLG of zero for chloroform in today's rule, it 
believes it has the authority to establish nonzero MCLGs for 
carcinogens if the scientific evidence supports this finding.
    In response to commenter's concerns with EPA using the proposed 
1996 Guidelines for Carcinogen Risk Assessment (EPA, 1996b) instead of 
the Agency's 1986 guidelines, EPA believes it is important to point out 
that the 1986 guidelines provide for departures from default 
assumptions such as low dose linear assessment. For example, the 1986 
EPA guidelines reflect the position of the OSTP (1985; Principle 26) 
``No 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 1986 guideline goes on to 
further 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.'' The EPA's 1996 Proposed Guidelines for 
Carcinogen Risk Assessment allow EPA to use other default approaches to 
estimate cancer risk than the historic, linearized multistage default 
when there is an understanding of an agent's mode of carcinogenic 
action. EPA believes that reliance on the 1986 guidance allows EPA to 
reach the same conclusion on the carcinogenic risk from chloroform as 
if the 1996 guidelines were used. The use of the best available science 
is a core EPA principle and is statutorily mandated by the SDWA 
amendments of 1996. The 1996 Proposed Guidelines for Carcinogen Risk 
Assessment reflect new science and are consistent with the existing 
1986 Guidelines for Carcinogen Risk Assessment. EPA considered the 1996 
proposed guidelines in assessing the health effects data for chloroform 
and the other contaminants discussed in the 1998 March NODA.
    EPA agrees with commenters that additional review by the FACA of 
the regulatory implications of a nonlinear approach is appropriate for 
policy reasons, and will initiate these discussions in the context of 
the Stage 2 DBPR FACA deliberations. In light of the November 1998 
statutory deadline to promulgate the Stage 1 DBP rule and the steps 
necessary to complete a final rule, EPA has concluded that there is not 
enough time to meet with the SAB and FACA, provide ample opportunity 
for debate, resolve differing points of views, and complete additional 
analysis to meet stakeholders policy concerns in the context of the 
Stage 1 DBP rule. EPA notes, however, that regardless of the MCLG for 
chloroform, the MCL for the THMs remains at 0.08 mg/L. Since the MCL is 
the enforceable standard that water systems will be required to meet, a 
nonlinear or low dose linear extrapolation to derive the MCLG will not 
have a direct impact on the compliance obligations of public water 
systems or on the levels of chloroform allowed in public water systems, 
although it may be relevant to development of enforceable regulatory 
limits established under future rules.
2. MCLG for Bromodichloromethane (BDCM)
    a. Today's Rule. The final MCLG for BDCM is zero. The zero MCLG is 
based on the classification of BDCM as a probable human carcinogen. The 
MCLG was determined in a weight-of-evidence evaluation which considered 
all relevant health data including carcinogenicity and reproductive and 
developmental toxicity animal data. EPA believes the data are 
insufficient at this time to determine the mode of carcinogenic action 
for BDCM, and therefore a low dose linear extrapolation approach is 
used to estimate lifetime cancer risk as a default.
    b. Background and Analysis. In the 1994 Stage 1 DBPR proposal, the 
MCLG of zero for BDCM was based on large intestine and kidney tumor 
data from a National Toxicology Program (NTP) chronic animal study 
(NTP, 1987). Since the proposal, several new studies have been 
published on BDCM metabolism (EPA, 1997c). In addition, several new 
genotoxicity studies and short-term toxicity studies including 
reproductive evaluations were found for BDCM (EPA, 1997c). These new 
studies contribute to the weight-of-evidence conclusions reached in the 
1994 proposal. Based on this evidence, the final MCLG for BDCM is zero 
based on sufficient evidence of carcinogenicity in animals.
    c. Summary of Comments. Several commenters disagreed with the use 
of a

[[Page 69402]]

corn oil gavage animal cancer study to determine the MCLG for BDCM. 
Some commenters agreed with the EPA decision to use large intestine and 
kidney tumor data from the corn oil gavage study, but not liver tumor 
data in the quantitative estimation of carcinogenic risk. One commenter 
agreed that a low-dose linear extrapolation approach to dose-response 
assessment was appropriate at this time and consistent with EPA policy. 
However, this commenter suggested that EPA undertake chronic studies 
that include a drinking water study of BDCM and toxicokinetics. One 
commenter disagreed with the EPA conclusion that the evidence on the 
mutagenicity of BDCM is adequate.
    In response, EPA agrees with commenters that a drinking water study 
is preferable to a corn oil gavage study to assess risk from DBPs in 
drinking water. However, the NTP corn oil gavage study is the best data 
available on BDCM for a quantitative risk estimation at this time. BDCM 
is currently being tested for toxicokinetics and cancer in a chronic 
BDCM drinking water rodent study by the NTP. When these data are 
available, EPA will reassess the cancer risk of BDCM. EPA believes that 
the animal data currently available on BDCM are consistent with EPA 
cancer guidelines on classifying BDCM as a probable human carcinogen 
given the evidence on mutagenicity and given there was an increased 
incidence of tumors at several sites in the animals. Additionally, 
tumors were found in both sexes of two rodent species. Finally, there 
have been several new studies on the genotoxicity of BDCM that have 
supported a mutagenic potential for BDCM (EPA, 1997c)
3. MCLG for Dibromochloromethane (DBCM)
    a. Today's Rule. The final MCLG for DBCM is 0.06 mg/L. This MCLG is 
based on a weight of evidence evaluation of the cancer and noncancer 
data which resulted in the classification of DBCM as a possible human 
carcinogen.
    b. Background and Analysis. In the 1994 proposal, the MCLG of 0.06 
mg/L for DBCM was based on observed liver toxicity from a subchronic 
study and possible carcinogenicity (NTP, 1985). EPA is not aware of any 
new information that would change its evaluation of DBCM since the 
proposal. The final MCLG is therefore 0.06 mg/L.
    c. Summary of Comments. Several commenters disagreed with the 
additional safety factor of 10 to account for possible carcinogenicity 
that was used in the MCLG calculation. One commenter agreed with EPA's 
decision to base the MCLG on noncarcinogenic endpoints. Several 
commenters disagreed with the use of a corn oil gavage study to 
determine the MCLG for DBCM.
    In response, because the evidence of carcinogenicity was limited on 
DBCM (i.e., increased tumor response in only one of the two species 
tested), EPA classified DBCM as a possible human carcinogen. The 
additional factor of 10 to account for possible carcinogenicity follows 
EPA's science policy for establishing MCLGs (EPA, 1994a). EPA used 
liver effects from the NTP subchronic corn oil gavage study as the 
basis for the Reference Dose (RfD). EPA agrees with the comment that 
this is an appropriate basis for deriving the RfD for DBCM. EPA agrees 
with commenters that a drinking water study is preferable to a corn oil 
gavage study to assess risk from DBPs in drinking water. However, the 
NTP corn oil gavage study is the best data available on DBCM for 
derivation of the MCLG at this time. EPA does not plan to conduct 
additional chronic studies for DBCM but is conducting additional 
toxicokinetics and short term drinking water studies on DBCM to better 
understand the potential risk associated with exposure through drinking 
water.
4. MCLG for Bromoform
    a. Today's Rule. The final MCLG for bromoform is zero. The zero 
MCLG is based on a weight-of-evidence classification that bromoform is 
a probable human carcinogen based on a consideration of all relevant 
health data including cancer and noncancer effects. EPA believes the 
data are insufficient at this time to determine the mode of 
carcinogenic action for bromoform, and therefore a low dose linear 
extrapolation approach is used to estimate lifetime cancer risk as a 
default.
    b. Background and Analysis. The proposed MCLG for bromoform was 
zero. This MCLG was based on an NTP chronic animal carcinogenicity 
study (NTP, 1989). Since the proposal, new studies on the genotoxicity 
of bromoform were found. However, these new studies do not support 
changing the proposed MCLG of zero for bromoform. The final MCLG for 
bromoform is therefore zero.
    c. Summary of Comments. Several commenters agreed with EPA's 
classification for bromoform as a probable carcinogen. Other commenters 
disagreed with this classification stating that there was insufficient 
evidence available because tumors were found in only one species and 
the increased number of tumors was small. These commenters generally 
felt that EPA should use an RfD approach in quantifying the risk for 
bromoform. Some commenters encouraged EPA to conduct more experiments 
on bromoform toxicity. Some commenters were concerned with the use of a 
corn oil gavage study to determine carcinogenic risk.
    In response, although the increase in tumors was small, the 
increase was considered significant because large intestine tumors in 
both male and female rats are rare and thus provides sufficient 
evidence to classify bromoform as a probable human carcinogen. EPA does 
not plan on conducting additional chronic testing for bromoform at this 
time, but is conducting toxicokinetic studies and shorter term drinking 
water studies to better understand the potential risk associated with 
exposure to bromoform in drinking water. EPA agrees with commenters 
that drinking water studies are preferable to a corn oil gavage study 
to assess risk from DBPs in drinking water. However, the NTP corn oil 
gavage study is the best data available on bromoform for derivation of 
the MCLG.
5. MCLG for Dichloroacetic Acid (DCA)
    a. Today's Rule. The final MCLG for DCA is zero. EPA has developed 
a weight-of-evidence characterization for DCA in which it evaluated all 
relevant health data (both cancer and noncancer effects). The MCLG of 
zero is based on sufficient evidence of carcinogenicity in animals 
which indicates that DCA is a probable human carcinogen (likely under 
proposed cancer guidelines). EPA believes the data are insufficient at 
this time to determine the mode of carcinogenic action for DCA and that 
the data is insufficient to quantify the potential cancer risk from 
DCA.
    b. Background and Analysis. EPA proposed an MCLG of zero for DCA. 
This was based on classifying DCA as a probable human carcinogen in 
accordance with the 1986 EPA Guidelines for Carcinogen Risk Assessment 
(EPA, 1986). The DCA categorization was based primarily on findings of 
liver tumors in rats and mice, which was regarded as ``sufficient'' 
evidence in animals. No lifetime risk calculation was conducted at the 
time of the proposal because there was insufficient data to quantify 
the risk (EPA, 1994a).
    As pointed out in the 1997 and 1998 DBP NODAs, several 
toxicological studies have been identified for DCA since the 1994 
proposal (EPA, 1997c). In addition, EPA co-sponsored an ILSI project in 
which an expert panel was

[[Page 69403]]

convened to explore the application of the EPA's 1996 Proposed 
Guidelines for Carcinogen Risk Assessment (EPA, 1996b) to the available 
data on the potential carcinogenicity of chloroform and DCA. The panel 
considered data on DCA which included chronic rodent bioassay data and 
information on mutagenicity, tissue toxicity, toxicokinetics, and other 
mode of action information. The panel concluded that the potential 
human carcinogenicity of DCA ``cannot be determined'' primarily because 
of the lack of adequate rodent bioassay data (ILSI, 1997).
    EPA prepared a new hazard characterization regarding the potential 
carcinogenicity of DCA in humans (EPA, 1998b). One objective of this 
report was to develop a weight-of-evidence characterization using the 
principles of the EPA's 1996 Proposed Guidelines for Carcinogen Risk 
Assessment (EPA, 1996b) which are consistent with the 1986 Guidelines. 
Another objective of the report was to consider new data since the 1994 
proposal and to address the issues raised by the 1997 ILSI panel 
report.
    EPA agreed with the ILSI panel report that the mode of action 
through which DCA induces liver tumors in both rats and mice cannot be 
reasonably determined at this time. EPA disagrees with the ILSI panel 
that the potential human carcinogenicity cannot be determined. Based on 
the hepatocarcinogenic effects of DCA in both rats and mice in multiple 
studies, as well as other date, for example, showing that DCA alters 
cell replication and gene expression, EPA concludes that DCA should be 
considered as a ``likely'' (probable) cancer hazard to humans (EPA, 
1998b). Therefore, as in the 1994 proposed rule, EPA believes that the 
MCLG for DCA should remain zero to assure public health protection.
    c. Summary of Comments. Some commenters agreed with the zero MCLG 
for DCA based on positive carcinogenic findings in two animal species. 
Several commenters stated that a zero MCLG was inappropriate due to 
evidence which indicates a nongenotoxic mode of action for DCA. The 
comment was raised that the animal evidence was insufficient to 
consider DCA a likely (probable) human carcinogen, and that DCA should 
be considered at most suggestive of carcinogenicity.
    In response, EPA concludes that DCA should be considered as a 
probable (likely under the 1996 proposed guidelines) cancer hazard to 
humans (EPA, 1998b) based on the hepatocarcinogenic effects of DCA in 
both rats and mice in multiple studies, and mode of action related 
effects (e.g., mutational spectra in oncogenes, elevated serum 
glucocorticoid levels, alterations in cell replication and death). EPA 
considers the mode of action through which DCA induces liver tumors in 
both rats and mice to be unclear, and thus the likelihood of human 
hazard associated with low levels of DCA usually encountered in the 
environment or in drinking water is not sufficiently understood. EPA 
acknowledges that a mutagenic mechanism (i.e., direct DNA reactivity) 
may not be an important influence on the carcinogenic process at low 
doses. EPA believes that the lack of mutagenicity is not a sufficient 
basis to depart from a low dose linear default extrapolation approach 
for the cancer assessment. There must be other convincing evidence to 
explain how the tumors are caused by the chemical. The commenters have 
not presented such evidence. Although DCA tumor effects are associated 
with high doses used in the rodent bioassays, there is uncertainty 
regarding whether the mode of tumorgenesis is solely through mechanisms 
that are operative only at high doses. Therefore, as in the 1994 
proposed rule, EPA believes that the MCLG for DCA should remain as zero 
to assure public health protection. NTP is implementing a new two year 
rodent bioassay that will include full histopathology at lower doses 
than those previously studied. Additionally, studies on the mode of 
carcinogenic action are being done by various investigators including 
the EPA health research laboratory.
6. MCLG for Trichloroacetic Acid (TCA)
    a. Today's Rule. The final MCLG for TCA is 0.3 mg/L, as was 
proposed in 1994. This MCLG is based on developmental toxicity and 
limited evidence of carcinogenicity in animals.
    b. Background and Analysis. The 1994 proposed rule included a MCLG 
of 0.3 mg/L for TCA based on developmental toxicity and possible 
carcinogenicity based on limited evidence in animal studies (i.e., 
hepatocarcinogenicity in mice). Since the proposal, a 2-year 
carcinogenicity study on TCA (DeAngelo et al., 1997) found that TCA was 
not carcinogenic in male rats. As was discussed in the 1997 DBP NODA 
(EPA, 1997b), there have also been several recent studies examining the 
mode of carcinogenic action for TCA. These new studies suggest that TCA 
does not operate via mutagenic mechanisms. For a more in depth 
discussion of this new data refer to the 1997 DBP NODA (EPA, 1997b) and 
related support documents (EPA, 1997c). This new information does not 
alter the original assessment of the health effects of TCA based on 
developmental toxicity and limited evidence of carcinogenicity. 
Therefore, the MCLG will remain 0.3 mg/L.
    c. Summary of Comments. Several commenters agreed with the 
classification of TCA as a possible human carcinogen. One commenter 
felt that toxicity data on TCA indicated a threshold. Some commenters 
disagreed with the study selected for estimating the RfD (Smith et al. 
1989). Some commenters stated the uncertainty factors used to establish 
the RfD were too high.
    In response, EPA acknowledges that a DNA reactive mutagenic 
mechanism may not be involved in TCA's mode of carcinogenicity. Because 
an RfD was used in lieu of a quantitative cancer assessment for 
establishing the MCLG, however, there was no need to evaluate the mode 
of carcinogenic action for TCA at this time. EPA believes that the 
Smith et al. (1989) study is appropriate to use in quantifying risk 
from TCA since developmental toxicity was the most critical effect. EPA 
believes that an uncertainty factor of 3,000 is appropriate to account 
for inter and intraspecies differences (100), a lowest observed adverse 
effects level (LOAEL) (10), and lack of a two-generation reproductive 
study (3) (EPA, 1994a). These uncertainty factors are consistent with 
current Agency science policy on using uncertainty factors (EPA, 
1994a).
7. MCLG for Chlorite and MRDLG for Chlorine Dioxide
    a. Today's Rule. The final MCLG for chlorite is 0.8 mg/L and the 
final MRDLG for chlorine dioxide is 0.8 mg/L. The MCLG for chlorite was 
increased from the proposed value of 0.08 mg/L to 0.8 mg/L based on a 
weight-of-evidence evaluation of all health data on chlorite including 
a recent two-generation reproductive rat study sponsored by the 
Chemical Manufactures Association (CMA, 1996). The MRDLG for chlorine 
dioxide was increased from the proposed value of 0.3 mg/L to 0.8 mg/L 
based on a weight-of-evidence evaluation using all the health data on 
chlorine dioxide including the information on chlorite from the CMA 
study. EPA believes that data on chlorite are relevant to assessing the 
risks of chlorine dioxide because chlorine dioxide is rapidly reduced 
to chlorite. Therefore, the findings from the CMA study and previously 
described studies in the 1994 proposal were used to assess the risk for 
both chlorite and chlorine dioxide.
    b. Background and Analysis. The 1994 proposal included an MCLG of

[[Page 69404]]

0.08 mg/L for chlorite. The proposed MCLG was based on an RfD of 3 mg/
kg/d estimated from a lowest-observed-adverse-effect-level (LOAEL) for 
neurodevelopmental effects identified in a rat study by Mobley et al. 
(1990). This determination was based on a weight of evidence evaluation 
of all the available data at that time (EPA, 1994d). An uncertainty 
factor of 1000 was used to account for inter-and intra-species 
differences in response to toxicity (a factor of 100) and to account 
for use of a LOAEL (a factor of 10).
    The 1994 proposal included an MRDLG of 0.3 mg/L for chlorine 
dioxide. The proposed MRDLG was based on a RfD of 3 mg/kg/d estimated 
from a no-observed-adverse-effect-level (NOAEL) for developmental 
neurotoxicity identified from a rat study (Orme et al., 1985; EPA, 
1994d). This determination was based on a weight of evidence evaluation 
of all available health data at that time (EPA, 1994a). An uncertainty 
factor of 300 was applied that was composed of a factor of 100 to 
account for inter-and intra-species differences in response to toxicity 
and a factor of 3 for lack of a two-generation reproductive study 
necessary to evaluate potential toxicity associated with lifetime 
exposure. To fill this important data gap, the CMA sponsored a two-
generation reproductive study in rats (CMA, 1996).
    As described in more detail in the 1998 NODA (EPA, 1998a), EPA 
reviewed the CMA study and completed an external peer review of the 
study (EPA, 1997d). In addition, EPA reassessed the noncancer health 
risk for chlorite and chlorine dioxide considering the new CMA study 
(EPA, 1998d). This reassessment was also peer reviewed (EPA, 1998d). 
Based on this reassessment, EPA requested comment in the 1998 NODA 
(EPA, 1998a) on changing the proposed MCLG for chlorite from 0.08 mg/L 
to 0.8 mg/L based on the NOAEL identified from the new CMA study which 
reinforced the concern for neurodevelopmental effects associated with 
short-term exposures.
    EPA determined that the NOAEL for chlorite should be 35 ppm (3 mg/
kg/d chlorite ion, rounded) based on a weight-of-evidence approach. The 
data considered to support the NOAEL are summarized in EPA (1998d) and 
included the CMA study as well as previous reports on developmental 
neurotoxicity and other adverse health effects (EPA, 1998d). EPA 
continues to believe, as stated in the 1998 NODA (EPA, 1998a), that the 
RfD for chlorite should be 0.03 mg/kg/d (NOAEL of 3 mg/kg/d with an 
uncertainty factor of 100) and that a MCLG of 0.8 mg/L is appropriate. 
EPA has concluded that the RfD for chlorine dioxide should be 0.03 mg/L 
(NOAEL of 3 mg/kg/d with an uncertainty factor of 100) and that a MRDLG 
of 0.8 mg/L is appropriate.
    c. Summary of Comments. EPA received numerous comments on the 1994 
proposal (EPA, 1994a) and 1998 NODA (EPA, 1998a). The major comment 
from the 1994 proposal was that reliance on the Mobley et al. (1990) 
study for the MCLG for chlorite and the Orme et al. (1985) study for 
chlorine dioxide were inappropriate and that the results from the CMA 
study must be evaluated before any conclusions on the MCLG for chlorite 
or chlorine dioxide could be drawn. In relation to the 1998 NODA, 
several commenters supported changing the MCLG for chlorite and MRDLG 
for chlorine dioxide while others were concerned that the science did 
not warrant a change in these values. The major comments submitted 
against raising the MCLG and MRDLG focused on several issues. First, 
one commenter argued that the 1000-fold uncertainty factor used for 
chlorite in the proposal should remain in place because the CMA study 
used to reduce the uncertainty factor was flawed. Second, several 
commenters indicated that the LOAEL should be set at the lowest dose 
level (35 ppm) because certain effects at the lowest dose tested may 
have been missed. Finally, some commenters argued that an additional 
safety factor should be included to protect children and drinking water 
consumption relative to the body weight of children should be used 
instead of the default assumption of 2 L per day and 70 kg adult body 
weight.
    EPA agrees with commenters on the 1994 proposal that the results 
from the CMA should be factored into any final decision on the MCLG for 
chlorite and chlorine dioxide. As explained in more detail in the 1998 
DBP NODA (EPA, 1998a), EPA considered the findings from the CMA study 
along with other available data to reach its conclusions regarding the 
MCLG and MRDLG for chlorite and chlorine dioxide.
    EPA disagrees with the commenter who suggested that the 1000-fold 
uncertainty factor for chlorite should remain because the CMA study was 
flawed. The study design for the neurodevelopmental component of the 
CMA study was in accordance with EPA's testing guidelines at the time 
the study was initiated. EPA had previously reviewed the study protocol 
for the CMA neurotoxicity component and had approved the approach. 
While EPA initially had some questions regarding the design of the 
neurodevelopmental component of the study (Moser, 1997), subsequent 
information submitted by the CMA provided clarification on certain 
aspects of the study design (CMA, 1998). EPA agrees that even with the 
clarifications that there are some limitations with the 
neurodevelopmental component of the CMA study. EPA believes that the 
neuropathology components of the CMA study were adequate. The 
functional operation battery had some shortcomings in that forelimb and 
hindlimb grip strength and foot splay were not evaluated. EPA believes 
the results from the motor activity component of the CMA study were 
difficult to interpret because of the high variability in controls. 
However, in its evaluation of the MCLG for chlorite and chlorine 
dioxide, EPA did not rely solely on the CMA study, but used a weight-
of-evidence approach that included consideration of several studies. 
Thus, the shortcomings of one study are offset by the weight from other 
studies. EPA believes that the CMA study contributes to the weight-of 
the-evidence. The studies by Orme et al. (1985), Mobley et al. (1990), 
and CMA (1996) support a NOAEL of 3 mg/kg/d based on neurodevelopmental 
effects (e.g., decreased exploratory, locomotor behavior, decreased 
brain weight). Furthermore, the CMA study was reviewed by outside 
scientists as well as by EPA scientists. EPA's re-assessment for 
chlorite and chlorine dioxide presented in the 1998 March NODA was 
reviewed internally and externally in accordance with EPA peer-review 
policy. The three outside experts who reviewed the Agency's assessment 
agreed with the NOAEL of 3 mg/kg/day and the derived RfD.
    Finally, EPA disagrees that an additional safety factor should be 
applied to provide additional protection for children or that drinking 
water consumption relative to the body weight of children should be 
used in developing the MCLG. The MCLG and MRDLG presented for chlorite 
and chlorine dioxide are considered to be protective of susceptible 
groups, including children, given that the RfD is based on a NOAEL 
derived from developmental testing, which includes a two-generation 
reproductive study. A two-generation reproductive study evaluates the 
effects of chemicals on the entire developmental and reproductive life 
of the organism. Additionally, current methods for developing RfDs are 
designed to be protective for sensitive populations. In the case of 
chlorite and chlorine dioxide a factor of 10 was used to account for 
variability between the average human response and the

[[Page 69405]]

response of more sensitive individuals. In addition, the important 
exposure is that of the pregnant and lactating female and the nursing 
pup. The 2 liter per day water consumption and the 70 kg body weight 
assumptions are viewed as adequately protective of all groups.
    Based on a review of all the data and public comments, EPA believes 
that the MCLG for chlorite should be 0.8 mg/L and the MRDLG for 
chlorine dioxide should be 0.8 mg/L. EPA believes the MCLG and MRDLG 
are consistent with the discussions during the regulatory negotiations 
which recognized the need for an acceptable two-generation reproductive 
study prior to reducing the uncertainty factors for chlorite and 
chlorine dioxide. EPA believes the CMA provided an acceptable two-
generation study with which to reduce the uncertainty factors. In 
addition, EPA believes potential health concerns in the proposal with 
having a MCLG for chlorite significantly below the MCL are no longer 
relevant because the MCL for chlorite in today's rule will remain at 
1.0 mg/L while the MCLG has been revised to 0.8 mg/L. Given the margin 
of safety that is factored into the estimation of the MCLG of 0.8 mg/L, 
EPA believes that the MCL of 1.0 mg/L will be protective of public 
health of all groups, including fetuses and children.
    The MCLG for chlorite is based on an RfD of 0.03 mg/kg/d using a 
NOAEL of 3 mg/kg/d and an uncertainty factor of 100 to account for 
inter- and intra-species differences. The MCLG for chlorite is 
calculated to be 0.8 mg/L by assuming an adult tap water consumption of 
2 L per day for a 70 kg adult and using a relative source contribution 
of 80% (because most exposure to chlorite is likely to come from 
ingestion of drinking water--EPA,1998u). A more detailed discussion of 
this assessment is included in the public docket for this rule (EPA, 
1998d).
[GRAPHIC] [TIFF OMITTED] TR16DE98.001

    For chlorine dioxide the MCLG is based on a NOAEL of 3 mg/kg/d and 
applying an uncertainty factor of 100 to account for inter-and intra-
species differences in response to toxicity, the revised MRDLG for 
chlorine dioxide is calculated to be 0.8 mg/L. This MRDLG takes into 
account an adult tap water consumption of 2 L per day for a 70 kg adult 
and applies a relative source contribution of 80% (because most 
exposure to chlorine dioxide is likely to come from ingestion of 
drinking water--EPA, 1998u). A more detailed discussion of this 
assessment is included in the public docket for this rule (EPA, 1998d).
[GRAPHIC] [TIFF OMITTED] TR16DE98.002

8. MCLG for Bromate
    a. Today's Rule. The final MCLG for bromate is zero. The zero MCLG 
is based on a weight-of-evidence evaluation of both the cancer and 
noncancer effects which indicates there is sufficient laboratory animal 
data to conclude that bromate is a probable (likely under the 1996 
proposed cancer guidelines) human carcinogen. EPA believes the data are 
insufficient at this time to determine the mode of carcinogenic action 
for bromate, and therefore a low dose linear extrapolation approach is 
used to estimate lifetime cancer risk as a default.
    b. Background and Analysis. The 1994 proposed rule included a MCLG 
of zero for bromate based on a determination that bromate was a 
probable human carcinogen. This determination was based on results from 
a two species rodent bioassay by Kurokawa et al. (1986a and 1986b) that 
found kidney tumors in rats. Since the 1994 proposed rule, EPA has 
completed and analyzed a new chronic cancer study in male rats and mice 
for potassium bromate (DeAngelo et al., 1998). EPA reassessed the 
cancer risk associated with bromate exposure (EPA, 1998e), had this 
reassessment peer reviewed (EPA, 1998e), and presented its findings in 
the March 1998 NODA (EPA, 1998a). The new rodent cancer study by 
DeAngelo et al. (1998) contributes to the weight of the evidence for 
the potential human carcinogenicity of potassium bromate and confirms 
the study by Kurokawa et al. (1986 a,b).
    c. Summary of Comments. Several commenters supported the zero MCLG 
for bromate. Others believed the MCLG of zero was not justified because 
there is evidence of a carcinogenic threshold. This evidence indicates 
that bromate causes DNA damage indirectly via lipid peroxidation, which 
generates oxygen radicals which in turn induce DNA damage. Other 
commenters argued that even if there is no carcinogenic threshold, EPA 
has overstated the potency of bromate by using the linearized 
multistage model and should instead use the Gaylor-Kodell model.
    In response, EPA disagrees with commenters who believed that the 
zero MCLG was inappropriate. At this time, under the principles of both 
the 1986 EPA Guidelines for Carcinogen Risk Assessment (EPA, 1986) and 
the draft 1996 EPA Proposed Guidelines for Carcinogen Risk Assessment 
(EPA, 1996b) weight-of-evidence approach, bromate is considered to be a 
probable or likely human carcinogen. This weight of evidence conclusion 
of potential human carcinogenicity is based on sufficient experimental 
findings that include the following: tumors at multiple sites in rats; 
tumor responses in both sexes; and evidence for mutagenicity including 
point mutations and chromosomal aberrations in in vitro genotoxicity 
assays. Furthermore, EPA believes there is insufficient evidence at 
this time to draw conclusions regarding the mode of carcinogenic action 
for bromate. EPA acknowledges there are studies available showing that 
bromate may generate oxygen radicals which increase lipid peroxidation 
and damage DNA. However, no data are available that link this proposed 
mechanism to tumor induction. Thus, EPA believes that while there are 
studies which provide some evidence to support the commenters' claims, 
these studies are insufficient at this time to establish

[[Page 69406]]

lipid peroxidation and free radical production as key events 
responsible for the induction of the multiple tumor responses seen in 
the bromate rodent bioassays (EPA, 1998e). Given the uncertainty about 
the mode of carcinogenic action for bromate, EPA believes it is 
appropriate to use the default assumption of low dose linearity to 
estimate the cancer risk and establish the MCLG of zero for bromate. 
EPA is conducting additional studies investigating the mode of action 
for bromate.
    EPA also disagrees with commenters who suggested that the Gaylor-
Kodell model should be used for low-dose extrapolation of the bromate 
data. In the 1998 NODA, a low dose linear extrapolation of the DeAngelo 
et al. (1998) data was conducted using a one-stage Weibull time-to-
tumor model. The Weibull model was considered to be the preferred 
approach to account for the reduction in animals at risk that may be 
due to the decreased survival observed in the high dose group toward 
the end of the study. The estimate of cancer risk from the DeAngelo et 
al. (1998) study is similar with the risk estimate derived from the 
Kurokawa et al. (1986a) study presented in the 1994 proposed rule.
    Based on an evaluation of all the data and after review and 
consideration of the public comments, EPA believes the MCLG for bromate 
should be zero.
9. MCLG for Chloral Hydrate
    a. Today's Rule. EPA has decided to not include an MCLG for chloral 
hydrate in the Stage 1 DBPR. This decision is based on an analysis of 
the technical comments and on the fact that chloral hydrate will be 
controlled by the MCLs for TTHM and HAAs and by the treatment technique 
of enhanced coagulation.
    b. Background and Analysis. The 1994 proposed rule included an MCLG 
for chloral hydrate of 0.04 mg/L. This was based on a 90-day mice study 
by Sanders et al. (1982) which reported liver toxicity. A RfD of 0.0016 
mg/kg/d was used (LOAEL of 16 mg/kg/d with an uncertainty factor of 
10,000). In the 1997 DBP NODA (EPA,1997b) and supporting documents 
(EPA, 1997c), additional studies on chloral hydrate were discussed, 
however, these new studies did not indicate a change in the MCLG for 
chloral hydrate.
    c. Summary of Comments. The majority of commenters disagreed with 
the MCLG of 0.04 mg/L for chloral hydrate. Several commenters 
questioned the need for an MCLG for chloral hydrate. These commenters 
mentioned its low toxic potential and the fact that safe concentrations 
of chloral hydrate are substantially greater than those present in 
drinking water. Commenters also questioned the need for an MCLG for 
chloral hydrate because the MCLs for THMs and HAAs and the treatment 
technique of enhanced coagulation will adequately control for chloral 
hydrate and because there were no monitoring provisions proposed. Other 
commenters argued that the use of a 10,000 uncertainty factor and the 
selection of the Sanders et al. (1982) study as a basis for setting the 
MCLG were inappropriate.
    In response, EPA agrees with commenters that an MCLG for chloral 
hydrate is not needed. This is based on the fact that the TTHM and HAA 
MCLs and the treatment technique (i.e., enhanced coagulation/softening) 
will control for chloral hydrate, as well as other chlorination 
byproducts. In addition, chloral hydrate does not serve as an important 
indicator for other chlorination byproducts. The final rule, therefore, 
does not contain an MCLG for chloral hydrate. In light of this 
decision, EPA is not responding to comments on the uncertainty factor 
used as the basis for setting the MCLG.
10. MRDLG for Chlorine
    a. Today's Rule. EPA is promulgating an MRDLG of 4 mg/L for 
chlorine based on a NOAEL from a chronic study in animals.
    b. Background and Analysis. EPA proposed an MRDLG of 4 mg/L for 
chlorine. The MRDLG was based on a two-year rodent drinking water study 
in which chlorine was given to rats at doses ranging from 4 to 14 mg/
kg/day and mice at doses ranging from 8 to 24 mg/kg/day (NTP, 1990). 
Neither systemic toxicity, nor effects on body weight and survival were 
found. Thus, the MRDLG was based on a NOAEL of 14 mg/kg/day and 
application of a 100 fold uncertainty factor to account for inter- and 
intra-species differences (EPA, 1994a). New information on chlorine has 
become available since the 1994 proposal and was discussed in the 1997 
DBP NODA and is included in the public docket (EPA, 1997c). This new 
information did not contain data that would change the MRDLG. EPA has 
therefore decided to finalize the proposed MRDLG of 4 mg/L for 
chlorine.
    c. Summary of Comments. Several commenters agreed with EPA's 
conclusion that there is no animal evidence of carcinogenicity for 
chlorine. Some commenters also agreed with EPA that 4 mg/L was the 
appropriate MCLG. Several commenters agreed with the proposed relative 
source contribution of 80 percent for chlorine. Some commenters agreed 
with the uncertainty factor of 100 while others felt that it was too 
high. Some commenters encouraged EPA to consider children in estimating 
risk from chlorine.
    In response, EPA believes that an uncertainty factor of 100 is 
appropriate when a NOAEL from a chronic animal study is the basis for 
the RfD. Because current methods for developing RfDs are designed to be 
protective for sensitive subpopulations, the uncertainty factor of 100 
is considered protective of children. Furthermore, animal studies 
indicate that chlorine is not a developmental toxicant.
11. MRDLG for Chloramine
    a. Today's Rule. EPA is promulgating an MRDLG of 4 mg/L for 
chloramines based on a NOAEL from a chronic rodent study.
    b. Background and Analysis. The 1994 proposed Stage I DBPR included 
an MRDLG for chloramines at 4 mg/L based on a NOAEL of 9.5 mg/kg/d for 
lack of toxicity in chronic rodent drinking water study and on 
application of an uncertainty factor of 100 to account of inter- and 
intra-species differences (EPA, 1994h). New information on chloramines 
has become available since the 1994 proposal and was included in the 
1997 DBP NODA and is included in the public docket (EPA, 1997c). This 
new information did not contain data that would change the MRDLG. EPA 
has therefore decided to finalized the proposed MRDLG of 4 mg/L for 
chloramines.
    c. Summary of Comments. Several commenters agreed with the MRDLG of 
4 mg/L for chloramine (as chlorine). Some commenters felt that the 
MRDLG was too low due to conservative uncertainty factors. Many 
commenters agreed with EPA's conclusion that there is no animal 
evidence of carcinogenicity for chloramines. Many commenters agreed 
with the RSC of 80% for chloramine while other believed that the RSC 
should be higher.
    In response, EPA believes that the uncertainty factor of 100 in the 
MRDLG calculation is appropriate to protect public health including 
that of children and sensitive subpopulations. EPA believes that the 80 
percent is an appropriate ceiling for the RSC due to lack of exposure 
data on other sources of exposure.

B. Epidemiology

1. Cancer Epidemiology
    a. Today's Rule. EPA has evaluated all of the cancer epidemiology 
data and the corresponding public comments received on the 1994 
proposal (EPA,

[[Page 69407]]

1994a), 1997 NODA (EPA, 1997b), and 1998 NODA (EPA, 1998a). Based on 
this evaluation, EPA believes that the cancer epidemiology data 
provides important information that contributes to the weight-of-
evidence evaluation on the potential health risks from exposure to 
chlorinated drinking water. At this time, however, the cancer 
epidemiology studies are insufficient to establish a causal 
relationship between exposure to chlorinated drinking water and cancer; 
and are thus considered limited for use in quantitative risk 
assessment. EPA's weight-of-evidence evaluation of the potential risk 
posed by chlorinated drinking water is further discussed in section IV 
of this preamble.
    b. Background and Analysis. The preamble to the 1994 proposed rule 
discussed numerous cancer epidemiology studies that had been conducted 
over the past 20 years to examine the relationship between exposure to 
chlorinated water and cancer (EPA, 1994a). At the time of the 
regulatory negotiation, there was disagreement among the members of the 
Reg. Neg. Committee on the conclusions that could be drawn from these 
studies. Some members of the Committee felt that the cancer 
epidemiology data, taken in conjunction with the results from 
toxicological studies, provide ample and sufficient weight-of-evidence 
to conclude that exposure to DBPs in drinking water could result in 
increased cancer risk at levels encountered in some public water 
supplies. Other members of the Committee concluded that the cancer 
epidemiology studies on the consumption of chlorinated drinking water 
to date were insufficient to provide definitive information for the 
regulation.
    In the 1998 DBP NODA (EPA, 1998a), EPA discussed several new 
epidemiology studies that had been published since the 1994 proposal. 
EPA concluded in the 1998 NODA, based on a review of all the cancer 
epidemiology studies (including the more recent studies), that a causal 
relationship between exposure to chlorinated surface water and cancer 
has not yet been demonstrated. However, several studies have suggested 
a weak association in various subgroups. Results from recent 
epidemiology studies continue to support the decision to pursue 
regulations to provide additional DBP control measures as discussed in 
section IV.D of this preamble.
    c. Summary of Comments. Several commenters agreed with EPA's 
characterization that there was insufficient evidence to conclude that 
there was a causal relationship between exposure to chlorinated surface 
water and cancer. Other commenters disagreed with this characterization 
stating that they believed the evidence did indicate there was a strong 
association between exposure to chlorinated water and cancer. Other 
commenters stated that EPA had not clearly articulated the basis for 
its conclusions on the issue of causality.
    In response, EPA continues to believe that there is insufficient 
evidence, based on the epidemiology data, to conclude there is a causal 
association between exposure to chlorinated waters and cancer. EPA 
agrees, however, that the basis for its conclusion on causality was not 
clearly articulated. This judgement of causality was based on 
evaluating the existing cancer epidemiologic database for the following 
criteria: strength of association, consistency of the findings, 
specificity of the association, as well as other information concerning 
the temporal sequence and presence of a dose-response relationship, and 
biological plausibility (Federal Focus, 1996; EPA, 1986; EPA 1996b).
    EPA applied the criteria stated above to assess the possible 
causality of cancer using the best available cancer epidemiology 
studies (Cantor et al., 1985, McGeehin et al., 1993, King and Marrett, 
1996, Cantor et al., 1998, Freedman et al., 1997, Hildesheim et al., 
1998, Doyle et al., 1997). These studies found a weak association for 
bladder cancer, although the findings were not consistent within and 
among the studies. The specificity of the association, temporal 
association, and dose response relationship remain unknown. In 
addition, the biological mode of action has not been determined. Using 
the criteria for causality, the present epidemiologic data do not 
support a causal relationship between exposure to chlorinated drinking 
water and development of cancer at this time. This conclusion does not 
preclude the possibility that a causal link may be established at a 
later date by future epidemiology and toxicology studies.
    Some commenters argued that the epidemiological evidence indicated 
an increased risk for cancer by exposure to chlorinated drinking water, 
while others argued that the epidemiological evidence does not support 
a health effects concern. As stated above, EPA believes that, at this 
time, a causal link between exposure to chlorinated drinking water and 
development of cancer cannot be determined. However, EPA believes that 
the epidemiological evidence suggests a potential increased risk for 
bladder cancer. It is therefore prudent public health policy to protect 
against this potential public health concern in light of the 
uncertainties and given the large population (over 200 million people) 
potentially exposed.
2. Reproductive and Developmental Epidemiology
    a. Today's Rule. EPA has evaluated all of the reproductive and 
developmental epidemiology data and the public comments received on the 
1994 proposal, 1997 NODA, and the 1998 NODA. Based on this evaluation, 
EPA believes that the reproductive and developmental epidemiology data 
provides important information that contributes to the weight-of-
evidence evaluation on the potential risks from exposure to chlorinated 
drinking water. However, the reproductive epidemiology studies are 
insufficient to establish a causal relationship between exposure to 
chlorinated drinking water and reproductive and developmental effects 
and are limited for use in the quantification of risk.
    b. Background and Analysis. In the preamble to the 1994 proposed 
DBPR, EPA discussed several reproductive epidemiology studies (EPA, 
1994a). At the time of the proposal, EPA concluded that there was no 
compelling evidence to indicate a reproductive and developmental hazard 
due to exposure to chlorinated water because the epidemiologic evidence 
was inadequate and the toxicological data were limited. In 1993, an 
expert panel of scientists was convened by the International Life 
Sciences Institute to review the available human studies for 
developmental and reproductive outcomes and to provide research 
recommendations (EPA/ILSI, 1993). The expert panel concluded that the 
epidemiologic results should be considered preliminary given that the 
research was at a very early stage (EPA/ILSI, 1993; Reif et al., 1996). 
The 1997 NODA and the supporting documents (EPA, 1997c) presented 
several new studies (Savitz et al., 1995; Kanitz et al. 1996; and Bove 
et al., 1996) that had been published since the 1994 proposed rule and 
the 1993 ILSI panel review. Based on the new studies presented in the 
1997 NODA, EPA stated that the results were inconclusive with regard to 
the association between exposure to chlorinated waters and adverse 
reproductive and developmental effects (EPA, 1997b).
    In the 1998 DBP NODA (EPA, 1998a), EPA included the recommendations 
from an EPA convened expert panel in July 1997 to evaluate 
epidemiologic studies of adverse reproductive or developmental outcomes 
that may be associated with the consumption of disinfected drinking 
water published

[[Page 69408]]

since the 1993 ILSI panel review. A report was prepared entitled ``EPA 
Panel Report and Recommendations for Conducting Epidemiological 
Research on Possible Reproductive and Developmental Effects of Exposure 
to Disinfected Drinking Water'' (EPA, 1998f). The 1997 expert panel was 
also charged to develop an agenda for further epidemiological research. 
The 1997 panel concluded that the results of several studies suggest 
that an increased relative risk of certain adverse outcomes may be 
associated with the type of water source, disinfection practice, or THM 
levels. The panel emphasized, however, that most relative risks are 
moderate or small and were found in studies with limitations in design 
or conduct. The small magnitude of the relative risk found may be due 
to one or more sources of bias, as well as to residual confounding 
(factors not identified and controlled). Additional research is needed 
to assess whether the observed associations can be confirmed. In 
addition, the 1998 DBP NODA included a summary of a study by Waller et 
al. (1998) conducted in California and another study by Klotz and Pyrch 
(1998) conducted in New Jersey. EPA concluded that while the Waller et 
al. (1998) study does not prove that exposure to THMs in drinking water 
causes early term miscarriages, it does provide important new 
information that needs to be explored and that the study adds to the 
weight-of-evidence which suggests that exposure to DBPs may have an 
adverse health effect on humans. EPA indicated that the review of the 
Klotz and Pyrch study (1998) had not been completed in time for the 
1998 NODA.
    EPA has completed its review of the Klotz and Pyrch (1998) study 
and concluded that the results in the report provide limited evidence 
to substantiate the hypothesis that DBPs in drinking water cause 
adverse reproductive or developmental effects since the bulk of the 
findings are inconclusive. There is, however, a suggestion in the study 
that total THMs or some other component of surface water is associated 
with a small increased risk of neural tube defects; no significant 
associations, however, were observed with individual THMs, HAAs or 
other composite measures of exposure.
    c. Summary of Comments. Several commenters agreed with EPA's 
conclusions on the significance of the reproductive and developmental 
effects from the various studies. Others believed EPA had not 
accurately characterized the potential adverse reproductive and 
developmental effects from exposure to DBPs in drinking water.
    In response, EPA continues to believe that the available 
epidemiology data along with the toxicological findings suggest that 
exposure to DBPs may have adverse effects on humans. However, EPA 
believes the epidemiology evidence is insufficient at this time to 
conclude that there is a causal association between exposure to DBPs 
and adverse reproductive and developmental effects. As noted in the 
1998 NODA, EPA has an epidemiology and toxicology research program that 
is examining the relationship between exposure to DBPs and adverse 
reproductive and developmental effects. In addition, EPA is pursuing 
appropriate follow-up studies to see if the observed association in the 
Waller et al. (1998) study can be replicated elsewhere. EPA will also 
be working with the California Department of Health Services to improve 
estimates of exposure to DBPs in the existing Waller et al. study 
population. EPA will collaborate with the Centers for Disease Control 
and Prevention (CDC) in a series of studies to evaluate if there is an 
association between exposure to DBPs in drinking water and birth 
defects. EPA is also involved in a collaborative testing program with 
the NTP under which several individual DBPs have been selected for 
reproductive and developmental laboratory animal studies. This 
information will be used in developing the Stage 2 DBPR.

C. MCLs and BAT for TTHM, HAA5, Chlorite, and Bromate; MRDLs and BAT 
for Chlorine, Chloramines, and Chlorine Dioxide

    MCLs are enforceable standards which are established as close to 
the MCLG as feasible. Feasible means with the use of the best 
technology, treatment techniques, and other means which the 
Administrator finds available (taking costs into consideration) after 
examining for efficacy under field conditions and not solely under 
laboratory conditions.
    EPA is promulgating MCLs for two groups of DBPs and two inorganic 
byproducts. EPA is also promulgating MRDLs for three disinfectants. EPA 
is promulgating these MCLs and MRDLs at the levels proposed in 1994. 
Systems will determine compliance with the MCLs and MRDLs in the same 
manner as was proposed in 1994, except for chlorite. EPA determined 
that additional monitoring requirements for chlorite were necessary 
based on the findings from the CMA two-generation reproductive and 
developmental study.
    Along with introducing the concept of the MRDLG in the proposed 
rule, EPA also introduced the MRDL for the three disinfectants 
(chlorine, chloramines, and chlorine dioxide). The MRDLs are 
enforceable standards, analogous to MCLs, which recognize the benefits 
of adding a disinfectant to water on a continuous basis and to maintain 
a residual to control for pathogens in the distribution system. As with 
MCLs, EPA has set the MRDLs as close to the MRDLGs as feasible. The 
Agency has also identified the BAT which is feasible for meeting the 
MRDL for each disinfectant.
    EPA received similar comments on the use of the term MRDL as with 
MRDLG. The majority of commenters agreed with the use of the term MRDL 
for the disinfectants and therefore EPA is using the term MRDL in the 
final rule.
1. MCLs for TTHMs and HAA5
    a. Today's Rule. In today's rule, EPA is promulgating an MCL for 
TTHMs of 0.080 mg/L. TTHM is the sum of measured concentrations of 
chloroform, bromodichloromethane, dibromochloromethane, and bromoform. 
EPA is also promulgating an MCL for HAA5 of 0.060 mg/L. HAA5 is the sum 
of measured concentrations of mono-, di-, and trichloroacetic acids, 
and mono- and dibromoacetic acids. A system is in compliance with these 
MCLs when the running annual average of quarterly averages of all 
samples taken in the distribution system, computed quarterly, is less 
than or equal to the MCL. If the running annual average computed for 
any quarter exceeds the MCL, the system is out of compliance. EPA 
believes that by meeting MCLs for TTHMs and HAA5, water suppliers will 
also control the formation of other DBPs not currently regulated that 
may also adversely affect human health.
    EPA has identified the best available (BAT) technology for 
achieving compliance with the MCLs for both TTHMs and HAA5 as enhanced 
coagulation or treatment with granular activated carbon with a ten 
minute empty bed contact time and 180 day reactivation frequency 
(GAC10), with chlorine as the primary and residual disinfectant, as was 
proposed in 1994.
    b. Background and Analysis. The 1994 proposal for the Stage 1 DBPR 
included MCLs for TTHM and HAA5 at 0.080 and 0.060 mg/L, respectively 
(EPA, 1994a). In addition to the proposed MCLs, subpart H systems--
utilities treating either surface water or groundwater under the direct 
influence of surface water--that use conventional treatment (i.e., 
coagulation, sedimentation, and filtration) or precipitative softening 
would be

[[Page 69409]]

required to remove DBP precursors by enhanced coagulation or enhanced 
softening. The removal of TOC would be used as a performance indicator 
for DBP precursor control.
    As part of the proposed rule, EPA estimated that 17% of PWSs would 
need to change their treatment process to alternative disinfectants 
(ozone or chlorine dioxide) or advanced precursor removal (GAC or 
membranes) in order to comply with the Stage 1 requirements. This 
evaluation was important to assist in determining whether the proposed 
MCLs were achievable and at what cost. This evaluation required an 
understanding of the baseline occurrence for the DBPs and TOC being 
considered in the Stage 1 DBPR, an understanding of the baseline 
treatment in-place, and an estimation of what treatment technologies 
systems would use to comply with the Stage 1 DBPR requirements.
    In 1997, at the direction of the M-DBP Advisory Committee, the TWG 
reviewed MCL compliance predictions developed for the 1994 proposal 
because of concern by several Committee members that modifications to 
the rule would result in more PWSs not being able to meet the new TTHM 
and HAA5 MCLs without installation of higher cost technologies such as 
ozone or GAC. Some members were concerned that allowing disinfection 
inactivation credit prior to precursor removal (by enhanced coagulation 
or enhanced softening) in order to prevent significant reductions in 
microbial protection would result in higher DBP formation and force 
systems to install alternative disinfectants or advanced precursor 
removal to meet the 1994 proposed TTHM and HAA5 MCLs. As discussed 
later in today's document in Section III.E (Preoxidation CT Credit), 
most PWSs can achieve significant reduction in DBP formation through 
the combination of enhanced coagulation (or enhanced softening) while 
maintaining predisinfection. The TWG's analysis indicated that there 
would be a decrease in the percentage of PWSs that would need to 
install higher cost technologies. This decrease was attributed to 
changes in the proposed IESWTR which altered the constraints by which 
systems could comply with the MCLs. The requirements of the IESWTR 
would also prevent significant reduction in microbial protection as 
described in the 1997 NODA (EPA, 1997a) and elsewhere in today's 
Federal Register. EPA has included a discussion of the prediction of 
technology choices in Section IV (Economic Analysis) of today's rule 
and a more detailed discussion in the RIA for this rule (EPA, 1998g). 
EPA continues to believe the proposed MCLs are achievable without 
large-scale technology shifts.
    c. Summary of Comments. Several commenters questioned whether the 
TTHM MCL of 0.080 mg/L and the HAA5 MCL of 0.060 mg/L were set at a 
level that would preclude the use of chlorine as an effective 
disinfectant. EPA does not believe the MCLs will preclude the use of 
chlorine. While there are currently systems that are exceeding these 
MCLs, the Agency has concluded that most systems will be able to 
achieve compliance by relatively low cost alternatives such as: 
improved DBP precursor removal through enhanced coagulation or enhanced 
softening; moving the point of disinfection to reduce the reaction 
between chlorine and DBP precursors; the use of chloramines for 
residual disinfection instead of chlorine; or a combination of these 
alternatives.
    Many commenters also questioned the need for a modified TTHM MCL 
and a new MCL for HAA5. As discussed in section I.B.2. of today's rule, 
EPA believes the potential public health risks do justify a reduction 
in exposure to DBPs and hence a modification in the MCL for TTHMs and a 
new MCL for HAA5. Also as discussed in section IV of this rule, EPA 
continues to believe that the potential risks associated with both TTHM 
and HAA5 and unregulated DBPs will be reduced by the combination of 
these MCLs and DBP precursor removal through enhanced coagulation and 
enhanced softening.
    While most commenters agreed with EPA's definition of GAC10 and 
GAC20 (GAC with a 10 and a 20 minute empty bed contact time, 
respectively), several commenters thought that designating GAC as BAT 
meant that they would have to install GAC at their treatment plant. EPA 
is required to designate a BAT for any MCL that the Agency promulgates; 
however, a system may use any technology it wants to comply with the 
MCL. However, a system must install BAT prior to the State issuing a 
variance to one of these MCLs.
    Commenters also questioned the use of group MCLs for TTHM and HAA5, 
instead of MCLs for the individual DBPs, since a group MCL does not 
take into account differing health effects and potencies of individual 
DBPs. EPA continues to believe that regulating TTHMs and HAAs as group 
MCLs is appropriate at this time for several reasons. First, EPA does 
not have adequate occurrence data for individual trihalomethanes and 
haloacetic acids to develop national occurrence estimates which are 
needed for estimating the potential costs and benefits of the rule 
(although the Agency has an adequate database of group occurrence). 
Second, there is not an adequate understanding of how water quality 
parameters (such as pH, temperature, bromide, and alkalinity) affect 
individual THM and HAA formation. Third, EPA does not have an adequate 
understanding of how treatment technologies control the formation of 
individual THMs and HAAs to enable specifying appropriate MCLs for 
individual TTHMs or HAAs at this time. Finally, there are inadequate 
health data to characterize the potential health risks for several of 
the HAAs and to then determine the potential benefits from reduction in 
exposures. In conclusion, EPA continues to believe the most appropriate 
approach for reducing the health risk from all DBPs is by the 
combination of TTHM and HAA5 MCLs and DBP precursor removal.
    Some commenters stated that EPA may have underestimated HAA 
formation, especially in certain areas of the country. The Agency was 
aware that waters in particular regions of the country would be more 
difficult to treat in order to control for HAA5 than for TTHM. Based on 
additional data received since the proposal, EPA continues to believe 
that the HAA5 MCL can be met by most systems through the same general 
low-cost strategies as used for TTHM (e.g., improved DBP precursor 
removal, moving the point of disinfection, use of chloramines for 
residual disinfection) rather than higher cost alternatives (see 
section IV.C for cost estimates of technology treatment choices).
    Many commenters also requested that States be granted sufficient 
flexibility in implementing this rule. While the State must adopt rules 
that are at least as stringent as those published in today's rule, EPA 
has given the States and systems much latitude in monitoring plans 
(frequency and location), allowable disinfectants, and other rule 
elements. Much of this flexibility carries over from the 1979 TTHM Rule 
(EPA, 1979).
    Finally, some commenters stated that requirements in this rule are 
complicated. EPA acknowledges that this rule is complicated, but that 
this complexity is necessary in order to adequately and economically 
address the potential DBP risks. EPA was required to consider a host of 
complicating factors in developing regulatory requirements: different 
disinfectants, different health effects (acute and chronic), different 
DBP formation kinetics, different source water types and qualities, 
different treatment processes, and the need for

[[Page 69410]]

simultaneous compliance with other rules such as the Total Coliform 
Rule, Lead and Copper Rule, and Interim Enhanced Surface Water 
Treatment Rule. The Agency chose to evaluate all these factors by 
developing requirements that minimized impacts on various classes of 
systems while enabling States to implement the rule. In addition to the 
further description of the requirements in today's rule, EPA will 
publish a State implementation manual, a small system compliance 
manual, and a series of guidance manuals that will provide additional 
information to systems and States in implementing this rule.
    EPA has reviewed all comments and determined that the requirements 
promulgated today are necessary to control the occurrence of TTHM and 
HAA5 and are feasible to achieve. These requirements take into account 
the difficulties in simultaneously controlling risks from DBPs and 
pathogens, while appropriately addressing implementation and compliance 
issues.
2. MCL for Bromate
    a. Today's Rule. In today's rule, EPA is promulgating an MCL for 
bromate of 0.010 mg/L. Bromate is one of the principal byproducts of 
ozonation in bromide-containing source waters. The proposed MCL for 
bromate was 0.010 mg/l. A system is in compliance with the MCL when the 
running annual average of monthly samples, computed quarterly, is less 
than or equal to the MCL. If the running annual average computed for 
any quarter exceeds the MCL, the system is out of compliance. EPA has 
identified the BAT for achieving compliance with the MCL for bromate as 
control of ozone treatment process to reduce formation of bromate, as 
was proposed in 1994 (EPA, 1994a).
    b. Background and Analysis. For systems using ozone, a separate MCL 
was proposed for the primary inorganic DBP associated with ozone usage: 
bromate. Although the theoretical 10-4 risk level for 
bromate is 0.005 mg/l, an MCL of 0.010 mg/L was proposed because 
available analytical detection methods for bromate were reliable only 
to the projected practical quantification limit (PQL) of 0.01 mg/L 
(EPA, 1994a).
    In the preamble to the proposed rule, EPA requested comment on 
whether there were ways to set (or achieve) a lower MCL (i.e., 0.005 
mg/L [5 g/L]) and whether the PQL for bromate could be lowered 
to 5 g/L in order to allow compliance determinations for a 
lower MCL in Stage 1 of the proposed rule. The proposed MCL of 0.010 
mg/L for bromate was based on a projected PQL that would be achieved by 
improved methods. The PQL of the revised method is approximately 0.010 
mg/L for bromate, as discussed in Section III.G (Analytical Methods). 
At the time of the November 1997 NODA, EPA was not aware of any new 
information that would lower the PQL for bromate and thus allow 
lowering the MCL. As a result, EPA concluded that the proposed bromate 
MCL was appropriate.
    c. Summary of Comments. Several commenters were concerned that the 
bromate MCL may have been set at a level that would preclude the use of 
ozone. During the M-DBP Advisory Committee discussions, the TWG 
evaluated the feasibility of ozone for certain systems that were 
predicted to have problems in complying with the TTHM and HAA5 MCLs. 
While ozone was not feasible for all systems, it was feasible for many 
that did not have elevated source water bromide levels to react with 
ozone to form bromate. The TWG predicted that most of the systems not 
able to use ozone would be able to switch to chlorine dioxide for 
primary disinfection.
    EPA has reviewed all comments and determined that the requirements 
promulgated today are necessary to control the occurrence of bromate 
and are feasible to achieve. For additional discussion on the treatment 
technologies for controlling bromate formation and their costs see the 
Cost and Technology Document for Controlling Disinfectants and 
Disinfection Byproducts (EPA, 1998k). These requirements take into 
account the difficulties in simultaneously controlling risks from DBPs 
and pathogens, while appropriately addressing compliance and 
implementation issues. In addition, the Reg. Neg. Committee and the M-
DBP Advisory Committee supported these conclusions.
3. MCL for Chlorite
    a. Today's Rule. In today's rule, EPA is promulgating an MCL for 
chlorite of 1.0 mg/L. EPA has modified the monitoring requirements from 
the proposed rule for the reasons discussed in section III.A.7. The 
issue of monitoring and MCL compliance determinations as they relate to 
the health effect of concern for chlorite were discussed in the 
proposed rule (EPA, 1994a). CWSs and NTNCWSs using chlorine dioxide for 
disinfection or oxidation are required to conduct sampling for chlorite 
both daily at the entrance to the distribution system and monthly (3 
samples on the same day) within the distribution system. Additional 
distribution system monitoring is required when the chlorite 
concentration measured at the entrance to the distribution system 
exceeds a chlorite concentration of 1.0 mg/L. Distribution system 
monitoring may be reduced if certain conditions are met (described in 
section III.H of this rule).
    b. Background and Analysis. For systems using chlorine dioxide, EPA 
proposed a separate MCL for chlorite associated with its usage in 1994. 
The proposed chlorite MCL of 1.0 mg/L was supported by the Reg. Neg. 
Committee because 1.0 mg/L was the lowest level considered practicably 
achievable by typical systems using chlorine dioxide, from both 
treatment and monitoring perspectives. The MCLG was 0.08 mg/L, due (in 
part) to data gaps that required higher uncertainty factors in the MCLG 
determination. The CMA agreed to fund new health effects research on 
chlorine dioxide and chlorite--with EPA approval of the experimental 
design--to resolve these data gaps. EPA completed its review of the 
study and published its findings in a NODA in March 1998. Those 
findings led to a chlorite MCLG of 0.8 mg/L and support for an MCL of 
1.0 mg/L.
    c. Summary of Comments. Many commenters requested that EPA not 
modify the MCL for chlorite prior to receipt and evaluation of the CMA 
study, since lowering the MCL could preclude the use of chlorine 
dioxide for drinking water disinfection. EPA has evaluated the CMA 
study and concluded that the MCLG for chlorite should be 0.8 mg/L. EPA 
believes the proposed MCL of 1.0 mg/L, based on a three sample average 
to determine compliance, is appropriate because this is the lowest 
level achievable by typical systems using chlorine dioxide. In 
addition, considering the margin of safety that is factored into the 
estimate of the MCLG, EPA believes the MCL will be protective of public 
health. Once the final MCLG was established, EPA decided that the 
chlorite MCL should be finalized at the level proposed which was as 
close as economically and technically feasible to the MCLG, and 
modified the proposed requirements for monitoirng and compliance in 
response to the health concerns associated with chlorite.
    EPA has reviewed all comments and determined that the requirements 
promulgated today are necessary to control the occurrence of chlorite 
and are feasible to achieve. These requirements take into account the 
difficulties in simultaneously controlling risks from DBPs and 
pathogens, while appropriately addressing compliance and

[[Page 69411]]

implementation issues. In addition, the Reg. Neg. Committee and the M-
DBP Advisory Committee supported these conclusions.
4. MRDL for Chlorine
    a. Today's Rule. Chlorine is a widely used and highly effective 
water disinfectant. In today's rule, EPA is promulgating an MRDL for 
chlorine of 4.0 mg/L. As a minimum, CWSs and NTNCWSs must measure the 
residual disinfectant level at the same points in the distribution 
system and at the same time as total coliforms, as specified in 
Sec. 141.21. Subpart H systems may use the results of residual 
disinfectant concentration sampling done under the SWTR 
(Sec. 141.74(b)(6) for unfiltered systems, Sec. 141.74(c)(3) for 
systems that filter) in lieu of taking separate samples. Monitoring for 
chlorine may not be reduced.
    A system is in compliance with the MRDL when the running annual 
average of monthly averages of all samples, computed quarterly, is less 
than or equal to the MRDL. Notwithstanding the MRDL, operators may 
increase residual chlorine levels in the distribution system to a level 
and for a time necessary to protect public health to address specific 
microbiological contamination problems (e.g., including distribution 
line breaks, storm runoff events, source water contamination, or cross-
connections).
    EPA has identified the best means available for achieving 
compliance with the MRDL for chlorine as control of treatment processes 
to reduce disinfectant demand, and control of disinfection treatment 
processes to reduce disinfectant levels.
    b. Background and Analysis. The 1994 proposed Stage I DBPR included 
an MRDL for chlorine at 4.0 mg/L (EPA, 1994a). The MRDL for chlorine is 
equal to the MRDLG for chlorine. EPA requested comment on a number of 
issues relating to the calculation of the MRDLG for chlorine. New 
information on chlorine has become available since the 1994 proposal 
and was discussed in the 1997 NODA (EPA, 1997b). EPA believes that no 
new information has become available to warrant changing the proposed 
MRDL. EPA has therefore decided to promulgate the MRDL of 4.0 mg/L for 
chlorine.
    c. Summary of Comments. Some commenters expressed concern that the 
MRDL for chlorine is too high. These commenters were concerned that 4 
mg/L levels of chlorine would have a detrimental effect on piping 
materials and would cause taste and odor problems. One commenter 
supported the chlorine MRDL and the methods of calculating compliance 
with the MRDL. This commenter felt that 4.0 mg/L appropriately allows 
for disinfection under varying circumstances. One commenter requested 
that EPA increase the flexibility of utilities to meet the MRDL for 
chlorine during periods when chlorine levels in the distribution 
systems may need to be raised to protect public health.
    EPA believes that the MRDL of 4.0 mg/L for chlorine is appropriate 
to control for potential health effects (MRDLG is 4.0 mg/L) from 
chlorine while high enough to allow for control of pathogens under a 
variety of conditions. EPA also believes that compliance based on a 
running annual average of monthly averages of all samples, computed 
quarterly is sufficient to allow systems to increase residual chlorine 
levels in the distribution system to a level and for a time necessary 
to protect public health to address specific microbiological 
contamination problems and still maintain compliance. If a system has 
taste and odor problems associated with excess chlorine levels it can 
lower its level of chlorine. Since there may not be any health effects 
associated with taste and odor problems, EPA does not have a statutory 
requirement to address this concern.
5. MRDL for Chloramines
    a. Today's Rule. Chloramines are formed when ammonia is added 
during chlorination. In today's rule, EPA is promulgating an MRDL for 
chloramines of 4.0 mg/L (measured as combined total chlorine). As a 
minimum, CWSs and NTNCWSs must measure the residual disinfectant level 
at the same points in the distribution system and at the same time as 
total coliforms, as specified in Sec. 141.21. Subpart H systems may use 
the results of residual disinfectant concentration sampling done under 
the SWTR (Sec. 141.74(b)(6) for unfiltered systems, Sec. 141.74(c)(3) 
for systems that filter) in lieu of taking separate samples. Monitoring 
for chloramines may not be reduced.
    A PWS is in compliance with the MRDL when the running annual 
average of monthly averages of all samples, computed quarterly, is less 
than or equal to the MRDL. Notwithstanding the MRDL, operators may 
increase residual chloramine levels in the distribution system to a 
level and for a time necessary to protect public health to address 
specific microbiological contamination problems (e.g., including 
distribution line breaks, storm runoff events, source water 
contamination, or cross-connections).
    EPA has identified the best means available for achieving 
compliance with the MRDL for chloramines as control of treatment 
processes to reduce disinfectant demand, and control of disinfection 
treatment processes to reduce disinfectant levels.
    b. Background and Analysis. The 1994 proposed Stage 1 DBPR included 
an MRDL for chloramines at 4.0 mg/L (EPA, 1994a). The MRDL for 
chloramines is equal to the MRDLG for chloramines. EPA requested 
comment on a number of issues relating to the calculation of the MRDLG 
for chloramines. New information on chloramines has become available 
since the 1994 proposal and was cited in the 1997 NODA and is included 
in the public docket for this rule (EPA, 1997b). This new information 
did not contain data that would warrant changing the MRDL. EPA has 
therefore decided to promulgate the proposed MRDL of 4.0 mg/L for 
chloramines.
    c. Summary of Comments. Some commenters remarked that systems with 
high concentrations of ammonia would have difficulty meeting the MRDL 
for chloramine of 4.0 mg/L and still maintain adequate microbial 
protection. One commenter felt that there should not be a limit for 
chloramine residual due to variations in parameters such as 
distribution system configurations and temperature. One commenter felt 
that the MRDL for chloramines was too low and should not be set at the 
same level as the chlorine MRDL since chlorine is a stronger 
disinfectant than chloramines. This commenter felt that limiting the 
chloramine residual would reduce the capability to sustain high water 
quality in the distribution system. One commenter supported the 
chloramine MRDL and the methods of calculating compliance with the 
MRDL. This commenter felt that 4.0 mg/L adequately allows for 
disinfection under varying circumstances.
    EPA believes that compliance based on a running annual average of 
monthly averages of all samples, computed quarterly, is sufficient to 
allow systems to increase residual chloramine levels in the 
distribution system to a level and for a time necessary to protect 
public health to address specific microbiological contamination 
problems and still maintain compliance. The MRDL for chloramine does 
not limit disinfectant dosage but rather disinfectant residual in the 
distribution system. EPA therefore, believes that systems with high 
levels of ammonia should be able to comply with the MRDL. Systems that 
have difficulty sustaining high water quality in the distribution 
system should consider modifying their

[[Page 69412]]

treatment or maintenance procedures to reduce demand. Although chlorine 
is a stronger disinfectant than chloramine, EPA believes that an MRDL 
of 4.0 mg/L is sufficient to provide adequate microbial protection.
6. MRDL for Chlorine Dioxide
    a. Today's Rule. Chlorine dioxide is used primarily for the 
oxidation of taste and odor-causing organic compounds in water. It can 
also be used for the oxidation of reduced iron and manganese and color, 
and as a disinfectant and algicide. Chlorine dioxide reacts with 
impurities in water very rapidly, and is dissipated quickly. In today's 
rule, EPA is promulgating an MRDL of 0.8 mg/L for chlorine dioxide. 
Unlike chlorine and chloramines, the MRDL for chlorine dioxide may not 
be exceeded for short periods of time to address specific 
microbiological contamination problems because of potential health 
concerns with short-term exposure to chlorine dioxide above the MCL.
    CWSs and noncommunity systems must monitor for chlorine dioxide 
only if chlorine dioxide is used by the system for disinfection or 
oxidation. Monitoring for chlorine dioxide may not be reduced. If 
monitoring is required, systems must take daily samples at the entrance 
to the distribution system. If any daily sample taken at the entrance 
to the distribution system exceeds the MRDL, the system is required to 
take three additional samples in the distribution system on the next 
day. Systems using chlorine as a residual disinfectant and operating 
booster chlorination stations after the first customer must take three 
samples in the distribution system: one as close as possible to the 
first customer, one in a location representative of average residence 
time, and one as close as possible to the end of the distribution 
system (reflecting maximum residence time in the distribution system). 
Systems using chlorine dioxide or chloramines as a residual 
disinfectant or chlorine as a residual disinfectant and not operating 
booster chlorination stations after the first customer must take three 
samples in the distribution system as close as possible to the first 
customer at intervals of not less than six hours.
    If any daily sample taken at the entrance to the distribution 
system exceeds the MRDL and if, on the following day, any sample taken 
in the distribution system also exceeds the MRDL, the system will be in 
acute violation of the MRDL and must take immediate corrective action 
to lower the occurrence of chlorine dioxide below the MRDL and issue 
the required acute public notification. Failure to monitor in the 
distribution system on the day following an exceedance of the chlorine 
dioxide MRDL shall also be considered an acute MRDL violation.
    If any two consecutive daily samples taken at the entrance to the 
distribution system exceed the MRDL, but none of the samples taken in 
the distribution system exceed the MRDL, the system will be in nonacute 
violation of the MRDL and must take immediate corrective action to 
lower the occurrence of chlorine dioxide below the MRDL. Failure to 
monitor at the entrance to the distribution system on the day following 
an exceedance of the chlorine dioxide MRDL shall also be considered a 
nonacute MRDL violation.
    EPA has identified the best means available for achieving 
compliance with the MRDL for chlorine dioxide as control of treatment 
processes to reduce disinfectant demand, and control of disinfection 
treatment processes to reduce disinfectant levels.
    b. Background and Analysis. EPA proposed an MRDL for chlorine 
dioxide of 0.8 mg/L in 1994. The MRDL was determined considering the 
tradeoffs between chemical toxicity and the beneficial use of chlorine 
dioxide as a disinfectant. The Reg. Neg. Committee agreed to this MRDL 
with the reservation that it would be revisited, if necessary, after 
completion of a two-generation reproductive study by CMA.
    As discussed above for chlorite, a two-generation reproductive 
study on chlorite, which is relevant to health effects of chlorine 
dioxide, was completed by the CMA. EPA completed its review of this 
study and published its findings in a NODA in March 1998 (EPA, 1998a). 
Based on its assessment of the CMA study and a reassessment of the 
noncancer health risk for chlorite and chlorine dioxide, EPA concluded 
that the MRDLG for chlorine dioxide be changed from 0.3 mg/L to 0.8 mg/
L. Since this new MRDLG was equal to the proposed MRDL for chlorine 
dioxide, the MRDL will remain 0.8 mg/L.
    c. Summary of Comments. A number of commenters were concerned that 
the MRDL for chlorine dioxide not be lowered below the proposed level 
of 0.8 mg/L because this would preclude the use of chlorine dioxide as 
a water disinfectant. One commenter supported the MRDL for chlorine 
dioxide based on public health protection, adequate microbial 
protection, and technical feasibility. One commenter agreed that a 
running annual average of samples for compliance determination should 
not be allowed for chlorine dioxide. One commenter was concerned that 
the chlorine dioxide MRDL was too high and that EPA should consider 
children and vulnerable populations in establishing drinking water 
standards.
    EPA has reassessed the health effects data on chlorine dioxide, 
including the new CMA two-generation study and determined that the MRDL 
should remain at 0.8 mg/L as proposed. EPA believes that this MRDL is 
set at a technically feasible level for the majority of chlorine 
dioxide plants. This is the case because EPA considered children and 
susceptible populations in its MRDLG determination (EPA, 1998h). The 
MRDL is set as close to this MRDLG as is technically and economically 
feasible.

D. Treatment Technique Requirement

1. Today's Rule
    Today's rule establishes treatment technique requirements for 
removal of TOC to reduce the formation of DBPs by means of enhanced 
coagulation or enhanced softening. The treatment technique applies to 
Subpart H systems using conventional filtration treatment regardless of 
size. Subpart H systems are systems with conventional treatment trains 
that use surface water or ground water under the influence of surface 
water as their source. The treatment technique requirement has two 
steps of application. Step 1 specifies the percentage of influent TOC a 
plant must remove based on the raw water TOC and alkalinity levels. The 
matrix in Table III-1 specifies the removal percentages.

    Table III-1.--Required Removal of Total Organic Carbon by Enhanced Coagulation and Enhanced Softening for
                               Subpart H Systems Using Conventional Treatment a,\b
----------------------------------------------------------------------------------------------------------------
                                                                      Source water alkalinity (mg/L as CaCO3)
                                                                 -----------------------------------------------
                     Source water TOC (mg/L)                            0-60          >60-120          >120c
                                                                     (percent)       (percent)       (percent)
----------------------------------------------------------------------------------------------------------------
>2.0-4.0........................................................            35.0            25.0            15.0

[[Page 69413]]

 
>4.0-8.0........................................................            45.0            35.0            25.0
>8.0............................................................            50.0            40.0            30.0
----------------------------------------------------------------------------------------------------------------
a Systems meeting at least one of the conditions in Section 141.135(a)(2) (i)-(vi) of the rule are not required
  to meet the removals in this table.
b Softening systems meeting one of the two alternative compliance criteria in Section 141.135(a)(3) of the rule
  are not required to meet the removals in this table.
c Systems practicing softening must meet the TOC removal requirements in the last column to the right.

    Step 2 provides alternate performance criteria when it is 
technically infeasible for systems to meet the Step 1 TOC removal 
requirements. For systems practicing enhanced coagulation, Step 2 of 
the treatment technique requirement is used to set an alternative TOC 
removal requirement (i.e. alternative percent removal of raw water TOC) 
for those systems unable to meet the TOC removal percentages specified 
in the matrix. The alternative TOC removal percentage is determined by 
performing jar tests on at least a quarterly basis for one year. During 
the jar tests, alum or an equivalent dose of ferric coagulant is added 
in 10 mg/L increments until the pH is lowered to the target pH value. 
The target pH is the value the sample must be at or below before the 
incremental addition of coagulant can be discontinued. For the 
alkalinity ranges 0-60, >60-120, >120-240, and >240 mg/L (as 
CaCO3), the target pH values are 5.5, 6.3, 7.0, and 7.5, 
respectively. Once the Step 2 jar test is complete, the TOC removal 
(mg/L) is then plotted versus coagulant dose (mg/L). The alternative 
TOC removal percentage is set at the point of diminishing returns 
(PODR) identified on the plot.
    Today's rule defines the PODR as the point on the TOC versus 
coagulant dose plot where the slope changes from greater than 0.3/10 to 
less than 0.3/10 and remains less than 0.3/10. After identifying the 
PODR, the alternative TOC removal percentage can be set. If the TOC 
removal versus coagulant dose plot does not meet the PODR definition, 
the water is considered not amenable to enhanced coagulation and TOC 
removal is not required if the PWS requests, and is granted, a waiver 
from the enhanced coagulation requirements by the State. Systems are 
required to meet the alternative TOC removal requirements during full-
scale operation to maintain compliance with the treatment technique. 
For the technical reasons outlined in the 1997 DBP NODA (EPA 1997b), 
EPA has concluded that this definition of the PODR is a reliable 
indicator of the amount of TOC that is feasible to remove.
    Systems practicing enhanced softening are not required to perform 
jar testing under today's treatment technique as part of a Step 2 
procedure. Rather, they are required to meet one of three alternative 
performance criteria if they cannot meet the Step 1 TOC removal 
requirements. These criteria are: (1) Produce a finished water with a 
SUVA of less than or equal to 2.0 L/mg-m; (2) remove a minimum of 10 
mg/L magnesium hardness (as CaCO3); or (3) lower alkalinity 
to less then 60 mg/L (as CaCO3). All three of these 
alternative performance criteria are measured monthly and can be 
calculated quarterly as a running annual average to demonstrate 
compliance. As discussed in the 1997 DBP NODA (EPA 1997b) EPA has not 
been able, from a technical and engineering standpoint, to identify a 
Step 2 testing procedure at this time that allows softening systems to 
set an alternative TOC removal amount. Enhanced softening systems 
unable to meet the Step 1 TOC removal requirements or any of the three 
alternative performance criteria may apply to the State for a waiver 
from the treatment technique requirements. EPA believes the three 
alternative performance criteria listed above provide assurance that 
softening systems have maximized TOC removal to the extent feasible.
    Today's rule also provides alternative compliance criteria--which 
are separate and independent of the Step 2 enhanced coagulation 
procedure and the enhanced softening alternative performance criteria--
from the treatment technique requirements provided certain conditions 
are met. These criteria are:
    (1) the system's source water TOC is <2.0 mg/L;
    (2) the system's treated water TOC is <2.0 mg/L;
    (3) the system's source water TOC <4.0 mg/L, its source water 
alkalinity is >60 mg/L (as CaCO3), and the system is 
achieving TTHM <40g/L and HAA5 <30g/L (or the system 
has made a clear and irrevocable financial commitment to technologies 
that will meet the TTHM and HAA level);
    (4) the system's TTHM is <40g/L, HAA5 is <30g/L, 
and only chlorine is used for primary disinfection and maintenance of a 
distribution system residual;
    (5) the system's source water SUVA prior to any treatment is 
 2.0 L/mg-m; and
    (6) the system's treated water SUVA is  2.0 L/mg-m.
    Alternative compliance criteria 1, 2, 5, and 6 are determined based 
on monthly monitoring calculated quarterly as a running annual average 
of all measurements. Alternative compliance criteria 3 is based on 
monthly monitoring for TOC and alkalinity or quarterly monitoring for 
TTHMs and HAA5, calculated quarterly as a running annual average of all 
measurements. Alternative criteria 4 is determined based on monitoring 
for TTHMs and HAA5, calculated quarterly as a running annual average of 
all measurements. SUVA, an indicator of DBP precursor removal 
treatability, is defined as the UV-254 (measured in m-1) 
divided by the DOC concentration (measured as mg/L).
2. Background and Analysis
    The general structure of the 1994 proposed rule and today's final 
rule are similar. The 1994 proposal included an enhanced coagulation 
and enhanced softening treatment technique requirement for Subpart H 
systems. The 1994 proposed rule included a TOC removal matrix for Step 
1 TOC removal requirements and it also provided for a Step 2 jar test 
procedure for systems practicing enhanced coagulation. The PODR for the 
Step 2 procedure was defined as a slope of .3/10 on the TOC removal 
versus coagulant dose plot. The Step 2 procedure included a maximum pH 
value, now referred to as the ``target pH'' for conducting the jar 
tests and it also allowed systems to request a waiver from the State if 
the PODR was never

[[Page 69414]]

attained. The target pH values in the 1994 proposal were the same as 
those in today's final rule. A Step 2 procedure for enhanced softening 
systems was not specified in the proposal.
    The proposed rule also provided for a number of exceptions to the 
enhanced coagulation and enhanced softening requirements, but it did 
not include use of SUVA as an alternative compliance criteria.
    A major goal of the TOC removal treatment technique requirements 
was to minimize transactional costs to the States both in terms of 
limiting the number of systems seeking alternative performance criteria 
and in providing relatively simple methodologies for determining 
alternative performance criteria. In the 1997 DBP NODA (EPA 1997b), EPA 
presented new data and analysis and the basis for modifying the 
proposed criteria to those described in today's final rule. The 1997 
NODA also solicited public comment on EPA's intended changes to the 
proposal and the recommendations of the M-DBP Advisory Committee to 
EPA. An overview of the key points in the 1997 NODA most pertinent to 
modifying the treatment technique requirements are presented below.
    Data Supporting Changes in the TOC Removal Requirements. The 
proposed TOC removal percentages, which were set with the intent that 
90% of affected systems would be able to achieve them, were developed 
with limited data. Since the proposal, several jar studies and analyses 
of full-scale plant TOC removal performance have been performed. They 
were analyzed by EPA as part of the M-DBP Advisory Committee process. 
This data will not be thoroughly reviewed here; instead, the major 
points salient to development of the final regulation will be 
summarized. See the 1997 DBP NODA (EPA 1997b) to review EPA's detailed 
analysis of the new data.
    As discussed in greater detail in the 1997 DBP NODA, research by 
Singer et al. (1995) indicated that a significant number of waters, 
especially low-TOC, high-alkalinity waters in the first row of the 
proposed TOC removal matrix, would probably not be able to meet the TOC 
removal percentages and would therefore need to use the Step 2 protocol 
to establish alternative performance criteria. The Singer et al. (1995) 
study raised concern regarding the number of systems that might need to 
use the Step 2 procedure to set alternative performance criteria. A 
study by Malcolm Pirnie, Inc. and Colorado University addressed this 
issue by developing a nationally representative database of 127 source 
waters and used this data to develop a model to predict enhanced 
coagulation's ability to remove TOC from different source waters 
(Edwards, 1997; Tseng & Edwards, 1997; Chowdhury, 1997). The model was 
subsequently used to analyze the level or percentage of TOC removal 
that is operationally feasible to achieve for the boxes in the proposed 
TOC removal matrix. Nine predictive equations for TOC removal were 
developed, one for each box of the TOC removal matrix, to select TOC 
removal percentages that could be ``reasonably'' met by 90 percent of 
the systems implementing enhanced coagulation. The equations indicated 
that many systems having source waters within the low TOC boxes of the 
matrix (i.e. 2.0-4.0 mg/L, the first row of the matrix) would meet the 
Step 2 slope criterion before meeting the required TOC removal 
percentages. In other words, less than 90 percent of the systems in 
this row could achieve the proposed TOC removal with reasonable 
coagulant doses. The equations indicated that the TOC removal 
percentages in the medium and high TOC boxes (the bottom two rows of 
the matrix) could be met by approximately 90 percent of the systems in 
these boxes. The research team also examined 90th-percentile SUVA 
curves, in conjunction with the nine TOC removal curves, to predict 
what TOC removal percentage is appropriate for each of the nine boxes 
of the matrix.
    An analysis of full-scale TOC removal has also been performed since 
1994. Data was obtained from 76 treatment plants of the American Water 
Works Service Company (AWWSCo) system, plants studied by Randtke et al. 
(1994), and plants studied by Singer et al. (1995). These data 
represent a one-time sampling at each plant under current operating 
conditions when enhanced coagulation was not being practiced. This 
sampling is different from the proposed compliance requirements which 
would be based on an annual average of monthly samples. Based on 
current treatment at the plants in the study, 83 percent of the systems 
treating moderate-TOC, low-alkalinity water removed an amount of TOC 
greater than that required by the TOC removal matrix, whereas only 14 
percent of the systems treating water with low TOC and high alkalinity 
met the proposed TOC removal requirements. The results of the survey, 
coupled with the information discussed in the preceding paragraph, 
indicate that the proposed TOC removal percentages in the top row of 
the matrix might be too high for 90 percent of plants to avoid the Step 
2 procedure, while the removal percentages in the bottom two rows may 
be reasonable and allow 90 percent of plants to avoid the Step 2 
procedure. Therefore, the TOC removal percentages in the first row have 
been lowered 5.0 percentage points to enable 90 percent of plants to 
comply without unreasonable coagulant dosage or resorting to the Step 2 
procedure.
    Data Supporting the Use of SUVA as an Exemption from Treatment 
Technique Requirements. At the time of the proposal, insufficient data 
on SUVA was available to define precise criteria for when enhanced 
coagulation would not be effective for removing DBP precursors. The M-
DBP Advisory Committee examined the role of SUVA as an indicator of the 
amount of DBP precursor material enhanced coagulation is capable of 
removing. It has been well established that coagulation primarily 
removes the humic fraction of the natural organic matter (NOM) in water 
(Owen et al., 1993). Furthermore, Edzwald and Van Benschoten (1990) 
have found SUVA to be a good indicator of a water's humic content. The 
humic fraction of a water's organic content significantly affects DBP 
formation upon chlorination.
    A study by White et al. (1997) showed that waters with high initial 
SUVA values exhibited significant reductions in SUVA as a result of 
coagulation, demonstrating a substantial removal of the humic (and 
other UV-absorbing) components of the organic matter, whereas waters 
with low initial SUVA values exhibited relatively low reductions in 
SUVA. For all of the waters examined, the SUVA tended to plateau at 
high alum doses, reflecting that the residual organic matter was 
primarily non-humic and therefore unamenable to removal by enhanced 
coagulation. SUVA's ability to indicate the amount of humic matter 
present, and enhanced coagulation's ability to preferentially remove 
humic matter, logically establishes SUVA as an indicator of enhanced 
coagulation's ability to remove humic substances from a given water. 
The M-DBP Advisory Committee therefore recommended that a SUVA value 
 2.0 L/mg-m be an exemption from the treatment technique 
requirement and that this SUVA value also be added as a Step 2 
procedure.
    Effect of Coagulant Dose on TOC Removal for Enhanced Softening. At 
the time of proposal, limited data was available on the effectiveness 
of TOC removal by enhanced coagulation and enhanced softening and on 
conditions that define feasibility. Several studies examined the 
relationship between increased coagulant dose and TOC removal (Shorney 
et al., 1996; Clark et

[[Page 69415]]

al. 1994). These studies indicate some improvement in TOC removal with 
small doses of iron salts (5 mg/L ferric sulfate), but no additional 
TOC removal during softening occurred with increased coagulant addition 
(up to 25 mg/L dose). Pilot testing by the City of Austin's softening 
plant confirmed the study's jar test results by showing that increasing 
ferric sulfate doses beyond the level required for turbidity removal 
provided no additional TOC removal.
    Multiple jar tests on various waters performed by Singer et al. 
(1996) examined the relationship between use of lime and soda ash and 
TOC removal. Only lime and soda ash (no coagulants) were used in the 
tests. The study showed the removal of 10 mg/L of magnesium hardness 
would probably have less of an impact on plant residual generation than 
using a lime soda-ash process. However, the amount of residual material 
generated under both scenarios could be substantial.
    Step 2 Requirements for Softening Systems. As stated above, the 
proposed rule did not include a Step 2 procedure for softening plants 
because of a lack of data. The M-DBP Advisory Committee examined new 
data that had been collected since the proposal to determine if a Step 
2 procedure for softening plants could be identified. Data included the 
current TOC removals being achieved by softening plants covered by the 
ICR (49 plants). The data were analyzed to find the appropriate TOC 
removal levels for softening plants. The results of plotting the 
average TOC percent removals on a percentile basis indicated that the 
relative impact of meeting the TOC removal requirement in the proposed 
rule would be greatest in the low TOC group (>2-4 mg/L). However, 
forcing a plant to increase pH may require it to add soda ash (due to 
the decrease in alkalinity caused by high lime dose necessary to raise 
the pH). This would be a significant treatment change due to the 
additional solids generation and because significant amounts of 
magnesium hydroxide may precipitate at the higher pH. Most softening 
plants are normally operated without soda ash addition because of the 
high cost of soda ash, the additional sludge production, the increased 
chemical addition to stabilize the water, and the increased sodium 
levels in the finished water (Randtke et al., 1994 and Shorney et al., 
1996). Due to these difficulties, EPA does not currently believe that a 
lime and soda-ash softening process would be a viable Step 2 procedure 
for softening systems. The final rule instead specifies two alternative 
compliance criteria, mentioned earlier in this section, as a Step 2 
procedure for softening systems.
3. Summary of Comments
    A large number of comments on the 1994 proposal questioned whether 
the required TOC removal percentages could be obtained by 90 percent of 
affected systems. In response, since the time of proposal, a large body 
of additional data and analysis has been developed to help address this 
question. The analyses discussed above showed that the top row of the 
TOC removal matrix needed to be lowered by 5.0 percentage points to 
enable 90 percent of systems within the row to achieve the required TOC 
removal without unreasonable coagulant doses. Analysis also showed the 
TOC removal percentages contained in the two lower rows of the TOC 
removal matrix accurately reflected the TOC removal 90 percent of these 
systems could remove. EPA believes the final TOC removal matrix, which 
includes the adjustments to the top row mentioned above, accurately 
reflects the TOC removal that 90 percent of the systems affected by the 
rule could practically achieve.
    Commenters questioned why systems that meet the DBP Stage 1 MCLs 
for TTHM and HAA5 must still practice enhanced coagulation. The 
enhanced coagulation treatment technique is designed to remove DBP 
precursor material to help reduce the risks posed by DBPs. Also, EPA 
believes that enhanced coagulation would reduce the number of systems 
switching to alternative disinfectants, which was a goal of the Reg. 
Neg. Committee. EPA believes that even if systems are meeting the MCLs, 
an additional risk reduction benefit can be achieved through removal of 
DBP precursor material at a relatively low cost to the system. 
Therefore, systems that meet the MCLs must still practice enhanced 
coagulation to decrease the risks posed by DBPs in general.
    The Agency received numerous comments on the 1994 proposal that 
expressed doubt regarding the definition of the PODR. Specifically, the 
commenters stated that the accuracy of the slope criterion (0.3 mg/L 
TOC removed per 10 mg/L coagulant added) for determining the PODR was 
not supported with adequate data. The data developed since the proposal 
and the corresponding analysis demonstrate that the slope criterion 
accurately predicts the PODR. The analyses discussed above showed that 
there is a particular relationship between SUVA and the slope 
criterion, namely, that they both predict the PODR at the same point of 
the TOC removal versus coagulant dose curve. Since SUVA is a very good 
predictor of the humic fraction of TOC, which is the fraction 
preferentially removed by enhanced coagulation, and the PODR predicted 
by SUVA and the slope criterion agree, EPA believes the slope criterion 
of 0.3 mg/L TOC removal per 10 mg/L of coagulant addition accurately 
predicts the PODR.
    The majority of commenters did not support requiring the use of 
bench-scale filtration as part of the Step 2 enhanced coagulation 
procedure. The commenters generally believed that using filtration at 
bench scale is of limited value because the great majority of TOC is 
removed via sedimentation, not through filtration. Additionally, some 
commentors felt that attempting to replicate full-scale filtration at 
bench scale can contain inherent inaccuracy. EPA generally agrees that 
a Step 2 filtration procedure should not be required. The Agency 
believes that most of the TOC removed by conventional treatment plants 
is removed in the sedimentation basin rather than in the filters. 
Therefore, requiring a bench-scale filtration procedure as part of Step 
2 testing will not increase the accuracy of the procedure or its value 
to the treatment technique implementation. Accordingly, today's final 
rule does not require the use of a bench scale filtration procedure 
during Step 2 enhanced coagulation testing. Detailed guidance on 
conducting the Step 2 testing will be provided in the Guidance Manual 
for Enhanced Coagulation and Enhanced Precipatative Softening.
    Commenters expressed varied opinions regarding the frequency of 
Step 2 testing. Several commenters stated that the rule should not set 
a minimum testing frequency, but that it should be left to State 
discretion based on source water characteristics. Other commenters 
believed a minimum of quarterly monitoring should be required with a 
provision for more frequent testing to address source water quality 
events. EPA believes that Step 2 testing frequency should be related to 
seasonal and other variations in source water quality as these 
variations may influence the amount of TOC removal the treatment plant 
can achieve. Accordingly, EPA recommends that systems utilizing the 
Step 2 procedure for compliance perform Step 2 testing quarterly for 
one year after the effective data of the rule. The system may then 
apply to the State to reduce testing to a minimum of once per year. If 
the State does not approve the request for reduced testing frequency, 
the system must continue to test quarterly.

[[Page 69416]]

E. Predisinfection Disinfection Credit

1. Today's Rule
    Today's rule does not impose any constraints on the ability of 
systems to practice predisinfection and take microbial inactivation 
credit for predisinfection to meet the disinfection requirements of the 
SWTR. Utilities are free to take disinfection credit for 
predisinfection, regardless of the disinfectant used, for disinfection 
that occurs after the last point the source water is subject to surface 
water run-off and prior to the first customer.
2. Background and Analysis
    The 1994 proposed Stage 1 DBPR (EPA,1994a) discouraged the use of 
disinfectants prior to precursor (measured as TOC) removal by not 
allowing compliance credit for the SWTR's disinfection requirements to 
be taken prior to removal of a specified percentage of TOC. The 
proposed IESWTR options were intended to include microbial treatment 
requirements to prevent increases in microbial risk due to the loss of 
predisinfection credit. These options were to be implemented 
simultaneously with the Stage 1 DBPR. The purpose of not allowing 
predisinfection credit was to maximize removal of organic precursors 
(measured as TOC) prior to the addition of a disinfectant, thus 
lowering the formation of DBPs.
    Many drinking water systems use preoxidation to control a variety 
of water quality problems such as iron and manganese, sulfides, zebra 
mussels, Asiatic clams, and taste and odor. The 1994 proposed rule did 
not preclude the continuous addition of oxidants to control these 
problems. However, the proposed regulation, except under a few specific 
conditions, did not allow credit for compliance with disinfection 
requirements prior to TOC removal. Analysis supporting the proposed 
rule concluded that many plants would be able to comply with the Stage 
1 MCLs for THMs and HAA5 of 0.080 mg/L and 0.060 mg/L, respectively, by 
reductions in DBP levels as a result of reduced disinfection practice 
in the early stages of treatment. Also, enhanced coagulation and 
enhanced softening were thought to lower the formation of other 
unidentified DBPs as well. The 1994 proposal assumed that addition of 
disinfectant prior to TOC removal would initiate DBP formation through 
contact of the chlorine with the TOC, effectively eliminating the value 
of enhanced coagulation for DBP reduction. Finally, the analysis 
underlying the 1994 proposed elimination of the preoxidation credit 
assumed that the addition of disinfectant was essentially ``mutually 
exclusive'' to the goal of reducing DBP formation by the removal of 
TOC. As discussed below, new data developed since 1994 suggest this may 
not be the case.
    Reasons for Disinfectant Use. In order to obtain information on the 
impact that disallowing predisinfection would have on utilities' 
disinfection practices, a survey was sent out to ICR utilities to 
obtain information on their current predisinfection practices. The 
results of the survey of 329 surface water treatment plants indicated 
that 80 percent (263) of these plants use predisinfection for one or 
more reasons. The survey indicated that the majority of the plants 
using predisinfection were doing so for multiple reasons. However, the 
main reason reported for predisinfection was microbial inactivation. 
Algae control, taste and odor control, and inorganic oxidation, in that 
order, were the next most frequently cited reasons for practicing 
predisinfection. Seventy-seven percent of plants that predisinfected 
reported that their current levels of Giardia lamblia inactivation 
would be lowered if predisinfection was discontinued and no subsequent 
additional disinfection was added to compensate for change in practice. 
Eighty-one percent of plants that predisinfected would have to make 
major capital investments to make up for the lost logs of Giardia 
lamblia inactivation. For example, to maintain the same level of 
microbial protection currently afforded, construction to provide for 
additional contact time or use of a different disinfectant might be 
needed if predisinfection credit was eliminated.
    In addition to the ICR mail survey, results from EPA's 
Comprehensive Performance Evaluations (CPE) from 307 PWSs (4 to 750 
mgd) reported that 71% of the total number of plants used 
predisinfection and 93% of those that predisinfected used two or three 
disinfectant application points during treatment.
    Based on the above information, EPA believes that predisinfection 
is used by a majority of PWSs for microbial inactivation, as well as 
other drinking water treatment objectives. Therefore, disallowing 
predisinfection credit could influence systems to make changes in 
treatment to comply with the disinfection requirements of the SWTR or 
to maintain current levels of microbial inactivation.
    Impact of Point of Chlorination on DBP Formation. The results of a 
study by Summers et al. (1997) indicate that practicing enhanced 
coagulation, while simultaneously maintaining prechlorination, can 
still result in decreased DBP formation (especially for TOX and TTHM). 
Greater benefits are realized by moving the point of chlorination to 
post-rapid mixing or further downstream for HAA5 control, and to mid-
flocculation or post-sedimentation for TOX and TTHM control. These data 
show that the assumption made in the 1994 proposal, namely that 
application of any disinfectant prior to TOC removal would critically 
effect DBP formation, was not accurate. The data indicate that 
simultaneous employment of enhanced coagulation and predisinfection 
does not necessarily mean that DBP formation cannot be substantially 
controlled (see EPA 1997b for detailed analysis).
    Impact on Softening Plants. In order to obtain additional 
information on the current TOC removals being achieved by softening 
plants, a survey was sent to all the ICR softening utilities (49 
plants) requesting that they fill out a single page of information with 
yearly average, maximum and minimum values for multiple operating 
parameters for each softening plant. The survey showed that in spite of 
the fact that 78 percent of softening plants are using free chlorine 
for at least a portion of their disinfection, 90 percent of plants are 
currently meeting an 80 g/L MCL level for TTHMS. All the 
softening plants reported average HAA5 levels below 60 g/L. 
Without predisinfection credit, these plants may have to provide 
disinfection contact time after sedimentation, which could mean 
significantly increasing the free chlorine contact time to make up for 
a shortened detention time.
3. Summary of Comments
    Most commenters stated that the proposed elimination of 
predisinfection would result in many plants not being able to maintain 
existing levels of disinfection or comply with the SWTR disinfection 
requirements without making significant compensatory changes in their 
disinfection practice. Commenters were concerned that without 
predisinfection the level of microbial risk their customers were 
exposed to could significantly increase, and that eliminating microbial 
inactivation credit for predisinfection to comply with the SWTR might 
influence utilities to abandon predisinfection to more easily comply 
with the TTHM and HAA5 MCLs. EPA agrees with this concern and therefore 
the final rule has been modified from the proposal to allow 
predisinfection credit.

[[Page 69417]]

F. Requirements for Systems to Use Qualified Operators

    EPA believes that systems that must make treatment changes to 
comply with requirements to reduce the microbiological risks and risks 
from disinfectants and disinfection byproducts should be operated by 
personnel who are qualified to recognize and react to problems. 
Therefore, in today's rule, the Agency is requiring that all systems 
regulated under this rule be operated by an individual who meets State 
specified qualifications, which may differ based on size and type of 
the system. Subpart H systems already are required to be operated by 
qualified operators under the provisions of the SWTR (40 CFR 
141.70(c)). Current qualification or certification programs developed 
by the States should, in many cases, be adequate to meet this 
requirement for Subpart H systems. Also, States must maintain a 
register of qualified operators.
    EPA encourages States which do not already have operator 
certification programs in effect to develop such programs. The Reg. 
Neg. Committee and TWG believed that properly trained personnel are 
essential to ensure safer drinking water. States with existing operator 
certification programs may wish to update their programs for qualifying 
operators under the SWTR. In these cases, States may wish to indicate 
that their operator certification programs are being developed in 
accordance with EPA's new guidelines.

G. Analytical Methods

1. Today's Rule
    Chlorine (Free, Combined, and Total). Today's rule approves four 
methods for measuring free, combined, and total chlorine to determine 
compliance with the chlorine MRDL (using either free or total chlorine) 
and chloramines MRDL (using either combined or total chlorine): ASTM 
Method D1253-86 (ASTM, 1996), Standard Methods 4500-Cl D (APHA, 1995), 
4500-Cl F (APHA, 1995), and 4500-Cl G (APHA, 1995). Additionally, this 
rule approves two methods for measuring total chlorine to determine 
compliance with the chlorine MRDL and chloramines MRDL: Standard 
Methods 4500-Cl E (APHA, 1995) and 4500-Cl I (APHA, 1995). The rule 
also contains an additional method for measuring free chlorine to 
determine compliance with the chlorine MRDL: Standard Method 4500-Cl H 
(APHA, 1995).
    Chlorine Dioxide. Today's rule approves two methods for determining 
compliance with the chlorine dioxide MRDL: Standard Methods 4500-
ClO2 D (APHA, 1995) and 4500-ClO2 E (APHA 1995). 
EPA did not approve Standard Method 4500-ClO2 C (APHA, 
1995), which was included in the 1994 proposed rule. The Agency 
determined, in concurrence with the majority of commenters on this 
issue, that Standard Method 4500-ClO2 C is outdated and 
inaccurate in comparison to chlorine dioxide methods approved in 
today's rule and is inadequate for compliance monitoring.
    TTHM. Today's rule approves three methods for determining 
compliance with the TTHM MCL: EPA Methods 502.2 (EPA, 1995), 524.2 
(EPA, 1995), and 551.1 (EPA, 1995).
    HAA5. Today's rule approves three methods for determining 
compliance with the HAA5 MCL: EPA Methods 552.1 (EPA, 1992) and 552.2 
(EPA, 1995) and Standard Method 6251B (APHA, 1995).
    Bromate. Today's rule approves a method for determining compliance 
with the bromate MCL: EPA Method 300.1 (EPA, 1997e). EPA has 
demonstrated this method to be capable of quantifying bromate at the 
MCL of 10 g/L under a wide range of solution conditions. EPA 
did not approve EPA Method 300.0 (EPA, 1993b) for bromate analysis, 
although this method was included for analysis of bromate in the 1994 
proposed rule. As stated in the proposed rule, EPA Method 300.0 is not 
sensitive enough to measure bromate at the MCL established in today's 
rule. EPA Method 300.1 was developed subsequent to the proposed rule in 
order to provide a method with adequate sensitivity to assess bromate 
compliance.
    Chlorite. Today's rule approves two methods for determining 
compliance with the chlorite MCL: EPA Methods 300.0 (EPA, 1993b) and 
300.1 (EPA, 1997e). As described elsewhere in today's rule, chlorite 
compliance analyses are made on samples taken in the distribution 
system during monthly monitoring, or during additional distribution 
system monitoring as required. Today's rule establishes the following 
method for daily monitoring of chlorite: Standard Method 4500-
ClO2 E (APHA, 1995), amperometric titration. As stated 
elsewhere in today's rule, daily monitoring of chlorite is conducted on 
samples taken at the entrance to the distribution system. Commenters 
supported the use of amperometric titration as a feasible method for 
daily monitoring of chlorite.
    TOC. Today's Rule approves three methods for TOC analysis: Standard 
Methods 5310 B, 5310 C, and 5310 D, as published in the Standard 
Methods 19th Edition Supplement (APHA, 1996). EPA believes that all of 
these methods can achieve the precision and detection level necessary 
for compliance determinations required in today's rule when the quality 
control (QC) procedures contained in the method descriptions and this 
rule are followed. However, while any of these methods may be used, EPA 
advises that a consistent method be employed for all measurements in 
order to reduce the impact of possible instrument bias.
    In accordance with the concerns of commenters, today's rule 
requires certain QC procedures for TOC analyses in addition to those 
contained in the method descriptions. These additional QC steps are 
designed to increase the integrity of the analysis and have been found 
to be effective in data collection under the ICR. Filtration of samples 
prior to TOC analysis is not permitted, as this could result in removal 
of organic carbon. Where turbidity interferes with TOC analysis, 
samples should be homogenized and, if necessary, diluted with organic-
free reagent water. TOC samples must either be analyzed or must be 
acidified to achieve pH less than 2.0 by minimal addition of phosphoric 
or sulfuric acid as soon as practical after sampling, not to exceed 24 
hours. Samples must be analyzed within 28 days.
    SUVA (Specific Ultraviolet Absorbance). Today's rule establishes 
SUVA as an alternative criterion for demonstrating compliance with TOC 
removal requirements contained in today's rule. SUVA is a calculated 
parameter defined as the UV absorption at 254 nm (UV254) 
(measured as m-1) divided by the DOC concentration (measured 
as mg/L). If the UV absorption is first determined in units of 
cm-1, the SUVA equation is multiplied by 100 to convert to 
m-1, as shown below:
SUVA = 100 (cm/m) [UV254 (cm-1)/DOC (mg/L)]

    Two separate analytical methods are necessary to make this 
measurement: UV254 and DOC. Today's rule approves three 
methods for DOC analysis: Standard Methods 5310 B, 5310 C, and 5310 D, 
as published in the Standard Methods 19th Edition Supplement (APHA, 
1996); and approves Standard Method 5910 B (APHA, 1995) for 
UV254 analysis.
    The final rule contains QC steps for the SUVA analyses that are 
required in addition to those mandated in the method descriptions. 
These requirements were developed in response to comments solicited by 
EPA in the 1997 DBP NODA (EPA, 1997b) and are as follows:


[[Page 69418]]


--sample acquisition (DOC and UV254 samples used to 
determine a SUVA value must be taken at the same time and at the same 
location. SUVA must be determined on water prior to the addition of 
disinfectants/oxidants.)
--sample preservation (DOC samples must either be analyzed or must be 
acidified to achieve pH less than 2.0 by minimal addition of phosphoric 
or sulfuric acid as soon as practical after sampling, not to exceed 48 
hours. The pH of UV254 samples may not be adjusted.)
--holding times (DOC samples must be analyzed within 28 days of 
sampling. UV254 samples must be analyzed as soon as 
practical after sampling, not to exceed 48 hours.)
--filtration (Prior to analysis, UV254 and DOC samples must 
be filtered through a 0.45 m pore-diameter filter. DOC samples 
must be filtered prior to acidification.)
--background concentrations in the filtered blanks (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: TOC <0.5 mg/L.)

    Bromide. Today's rule approves the following two methods for 
monitoring bromide: EPA Methods 300.0 (EPA, 1993b) and 300.1 (EPA, 
1997e).
    Alkalinity. Today's rule approves three methods for measuring 
alkalinity: ASTM Method D1067-92B (ASTM, 1994), Standard Method 2320 B 
(APHA, 1995), and Method I-1030-85 (USGS, 1989).
    pH. Today's rule requires the use of methods that have been 
previously approved in Sec. 141.23(k) for measurement of pH.
    Approved analytical methods are summarized in Table III-2.

                                    Table III-2.--Approved Analytical Methods
----------------------------------------------------------------------------------------------------------------
              Analyte                 EPA method             Standard method                     Other
----------------------------------------------------------------------------------------------------------------
Chlorine (free, combined, total)..  ..............  4500-Cl D                         ASTM D1253-8.
                                    ..............  4500-Cl F
                                    ..............  4500-Cl G
(Total)...........................  ..............  4500-Cl E
                                    ..............  4500-Cl I
(Free)............................  ..............  4500-Cl H
Chlorine Dioxide..................  ..............  4500-ClO2 D
                                    ..............  4500-ClO2 E
TTHM..............................           502.2
                                             524.2
                                             551.1
HAA5..............................           552.1  625l B
                                             552.2
Bromate...........................           300.1
Chlorite (monthly)................           300.0
                                             300.1
(Daily)...........................  ..............  4500-ClO2 E
TOC/DOC...........................  ..............  5310 B
                                    ..............  5310 C
                                    ..............  5310 D
UV254.............................  ..............  5910 B
Bromide...........................           300.0
                                             300.1
Alkalinity........................  ..............  2320 B                            ASTM D1067-92B.
                                                                                      USGS I-1030-85.
pH................................           150.1  4500-H+B                          ASTM D1293-84.
                                             150.2  ................................  ..........................
----------------------------------------------------------------------------------------------------------------

2. Background and Analysis
    Chlorine (Free, Combined, and Total). In the 1994 proposed rule, 
EPA included all Standard Methods for analysis of free, combined, and 
total chlorine that were approved in today's rule.
    Chlorine Dioxide. The 1994 proposed rule included the same three 
methods for analyzing chlorine dioxide (ClO2) that are 
approved under the SWTR and ICR regulations. Two of these methods, 
Standard Methods 4500.ClO2 C (APHA, 1992) and 
4500.ClO2 E (APHA, 1992), are amperometric methods. The 
third proposed method was Standard Method 4500.ClO2 D (APHA, 
1992), a colorimetric test using the color indicator N,N-diethyl-p-
phenylenediamine (DPD).
    TTHM. The 1994 proposed rule included three methods for the 
analysis of TTHMs. They were EPA Methods 502.2, 524.2, and 551. In 
1995, EPA Method 551 was revised to EPA Method 551.1, rev. 1.0 (EPA, 
1995), which was approved for ICR monitoring under 40 CFR 141.142.
    EPA Method 551.1 has several improvements upon EPA Method 551. The 
use of sodium sulfate is strongly recommended over sodium chloride for 
the MTBE extraction of DBPs. This change was in response to a report 
indicating elevated recoveries of some brominated DBPs due to bromide 
impurities in the sodium chloride (Xie, 1995). Other changes to EPA 
Method 551.1 include a buffer addition to stabilize chloral hydrate, 
elimination of the preservative ascorbic acid, and modification of the 
extraction procedure to minimize the loss of volatile analytes. The 
revised method requires the use of surrogate and other quality control 
standards to improve the precision and accuracy of the method.
    HAA5. The 1994 proposed rule included two methods for the analysis 
of five haloacetic acids--EPA Method 552.1 (EPA, 1992) and Standard 
Method 6233B (APHA, 1992). Both methods use capillary column gas 
chromatographs equipped with electron capture

[[Page 69419]]

detectors. The two methods differ in the sample preparation steps. EPA 
Method 552.1 uses solid phase extraction disks followed by an acidic 
methanol derivitization. Standard Method 6233B is a small volume 
liquid-liquid (micro) extraction with methyl-t-butyl ether, followed by 
a diazomethane derivitization. Following the proposed rule, Standard 
Method 6233B was revised and renumbered 6251B (APHA, 1995) to include 
bromochloroacetic acid, for which a standard was not commercially 
available in 1994. Recognizing these improvements, EPA approved 
Standard Method 6251B for analysis under the ICR (40 CFR Part 141 or 
EPA, 1996a). Several commenters requested that the revised and 
renumbered method, Standard Method 6251B, also be approved for the 
analysis of haloacetic acids under the Stage 1 DBPR.
    In 1995 EPA published a third method for HAAs, EPA Method 552.2 
(EPA, 1995), and subsequently approved it for HAA analysis under the 
1996 ICR (40 CFR Part 141 or EPA, 1996a). EPA Method 552.2 is an 
improved method, combining the micro extraction procedure of Standard 
Method 6233B with the acidic methanol derivitization procedure of EPA 
Method 552.1. It is capable of analyzing nine HAAs.
    Bromate. The 1994 proposed rule required systems that use ozone to 
monitor for bromate ion. EPA proposed EPA Method 300.0 (EPA, 1993b) for 
the analysis of bromate and chlorite ions. However, at the time of the 
proposal, EPA was aware that EPA Method 300.0 was not sensitive enough 
to measure bromate ion concentration at the proposed MCL of 10 
g/L. EPA recognized that modifications to the method would be 
necessary to increase the method sensitivity. Studies at that time 
indicated that changes to the injection volume and the eluent chemistry 
would decrease the detection limit below the MCL. Many commenters to 
the 1994 proposal agreed that EPA Method 300.0 was not sensitive enough 
to determine compliance with a MCL of 10 g/L bromate ion, 
given that MCLs are typically set at 5 times the minimum detection 
levels (MDLs).
    Following the proposal, EPA improved EPA Method 300.0 and 
renumbered it as EPA Method 300.1 (EPA, 1997b). EPA Method 300.1 
specifies a new, high capacity ion chromatography (IC) column that is 
used for the analysis of all anions listed in the method, instead of 
requiring two different columns as specified in EPA Method 300.0. The 
new column has a higher ion exchange capacity that improves 
chromatographic resolution and minimizes the potential for 
chromatographic interferences from common anions at concentrations 
10,000 times greater than bromate ion. For example, quantification of 
5.0 g/L bromate is feasible in a matrix containing 50 mg/L 
chloride. Minimizing the interferences permits the introduction of a 
larger sample volume to yield method detection limits in the range of 
1-2 g/L.
    In the 1997 DBPR NODA (EPA, 1997b), EPA discussed EPA Method 300.1 
and projected that by using it laboratories would be able to quantify 
bromate with the accuracy and precision necessary for compliance 
determination with an MCL of 10 g/L. Although there would be a 
limited number of laboratories that would be qualified to do such 
analyses, EPA determined that there should be adequate laboratory 
capacity for bromate ion compliance monitoring by the time the rule 
becomes effective.
    Chlorite. The proposed rule required systems using chlorine dioxide 
for disinfection or oxidation to perform monthly monitoring for 
chlorite ion in the distribution system. EPA designated EPA Method 
300.0 (ion chromatography) for chlorite analysis. EPA considered other 
methods using amperometric and potentiometric techniques but decided 
that only the ion chromatography method (EPA Method 300.0) would 
produce results with the accuracy and precision needed for determining 
compliance. Subsequent to the proposed rule, EPA Method 300.0 was 
improved in order to achieve lower detection limits for bromate ion and 
renumbered as EPA Method 300.1.
    TOC. To satisfy requirements of the Stage 1 DBPR, the 1994 proposed 
rule directed that a TOC analytical method should have a detection 
limit of at least 0.5 mg/L and a reproducibility of  0.1 
mg/L over a range of 2 to 5 mg/L TOC. The proposed rule included two 
methods for analyzing TOC: Standard Methods 5310 C, which is the 
persulfate-ultraviolet oxidation method, and 5310 D, the wet-oxidation 
method (APHA, 1992). These methods were selected because, according to 
data published in Standard Methods (APHA 1992), they could achieve the 
necessary precision and detection limit. Standard Method 5310 B, the 
high-temperature combustion method, was considered but not proposed 
because it was described in Standard Methods (1992, APHA) as having a 
detection limit of 1 mg/L. The proposal stated that if planned 
improvements to the instrumentation used in Standard Method 5310 B were 
successful, the next version would be considered for promulgation. 
Revisions of Standard Methods 5310 B, C, and D were published in 
Standard Methods 19th Edition Supplement (APHA, 1996). The revised 
version of Standard Method 5310 B recognized the capacity of certain 
high temperature instruments to achieve detection limits below 1 mg/L 
using this method.
    SUVA (Specific Ultraviolet Absorbance). SUVA analytical methods 
were not addressed in the 1994 proposed rule because SUVA had not been 
developed and proposed as a compliance parameter for TOC removal 
requirements at that time. The analytical methods and associated QC 
procedures for DOC and UV254 approved in today's rule are 
those on which the Agency solicited comment in the 1997 DBPR NODA (EPA, 
1997b).
    Bromide. The 1994 proposed rule included EPA Method 300.0 for 
analysis of bromide. EPA believed that the working range of this method 
adequately covered the requirements proposed for bromide monitoring. As 
described above, EPA developed Method 300.1 for improved bromate 
analysis subsequent to the proposed rule. EPA Method 300.1 can also 
effectively measure bromide at the concentration of 50 g/L, 
required in today's rule for reduced monitoring of bromate.
    Alkalinity. The proposed rule included all methods approved by EPA 
for measuring alkalinity. These methods have all been approved in 
today's rule.
3. Summary of Comments
    Following is a discussion of major comments on the analytical 
methods requirements of the Stage 1 DBPR.
    Chlorine. A commenter to the 1994 proposal recommended approval of 
ASTM method D1253-86. EPA determined that this method is equivalent to 
Standard Method 4500-Cl D, and has approved this method in today's 
rule.
    Chlorine Dioxide. EPA received comments on the proposed rule 
detailing weaknesses of the methods selected to calculate 
ClO2. Commenters pointed out that other halogenated species, 
such as free chlorine, chloramines, and chlorite, as well as common 
metal ions (e.g. copper, manganese, chromate) will interfere with these 
methods. Additionally, where these methods determine concentrations by 
difference, they are potentially inaccurate and subject to propagation 
of errors. Commenters specifically criticized Standard Method 4500-
ClO2 C (APHA 1995), amperometric method I, which was 
characterized as outdated and inaccurate, and stated that Standard

[[Page 69420]]

Method 4500-ClO2 E (APHA 1995), amperometric method II, is a 
substantially better method. Consequently, in the 1997 DBP NODA, EPA 
requested comment on removing Standard Method 4500-ClO2 C 
from the list of approved methods for the analysis of chlorine dioxide 
for compliance with the MRDL.
    Comments on the 1997 DBPR NODA favored eliminating Standard Method 
4500.ClO2 C as an approved method for ClO2 
compliance analysis. EPA does not approve this method in today's rule. 
EPA recognizes that the two methods approved for ClO2 
monitoring under today's rule are subject to interferences. However, 
EPA believes that these methods can be used effectively to indicate 
compliance with the ClO2 MRDL when the quality control 
procedures contained in the method descriptions are followed. Several 
commenters also encouraged EPA to approve a more sensitive and specific 
method for ClO2 analysis, and suggested alternative methods 
including Acid Chrome Violet K, Lissamine Green B, and Chlorophenol 
Red. While EPA supports the development of improved analytical methods 
for chlorine dioxide, the Agency believes that at this time the methods 
suggested by commenters have not gone through the necessary performance 
validation processes to warrant their approval for compliance 
monitoring.
    Bromate. In the 1994 proposed rule, EPA discussed the fact that the 
current version of EPA Method 300.0 was not sensitive enough to measure 
bromate ion concentrations at the proposed MCL and requested comment on 
modifications to EPA Method 300.0 to improve its sensitivity. In the 
1997 NODA, EPA presented EPA Method 300.1 and requested comment on 
replacing EPA Method 300.0 with EPA Method 300.1 for the analysis of 
bromate.
    Commenters agreed that EPA Method 300.1 is a more sensitive method 
than EPA Method 300.0 for low level bromate analysis and the majority 
suggested that EPA Method 300.1 be the approved method for bromate 
analysis. One commenter requested that interlaboratory round-robin 
testing be conducted before EPA Method 300.1 is accepted for Stage 1 
DBPR compliance monitoring. EPA considers interlaboratory round-robin 
testing of EPA Method 300.1 to be unnecessary because this method is 
essentially an improvement of EPA Method 300.0 which is already 
approved. EPA Method 300.1 primarily makes use of a superior analytical 
column to achieve increased sensitivity for bromate analysis. Moreover, 
the efficacy of EPA Method 300.1 in a wide range of sample matrices is 
demonstrated by the performance validation data contained in the 
published method description. Based on a review of all the public 
comments, EPA is approving EPA Method 300.1 for bromate analysis in 
today's rule.
    Chlorite. EPA solicited comment in the 1997 DBPR NODA on approving 
EPA Method 300.1, in addition to EPA Method 300.0, for compliance 
analysis of chlorite. The majority of commenters on this issue favored 
approval of both methods and today's rule establishes both for 
determining compliance with the chlorite MCL.
    In the 1994 proposed rule, EPA requested comment on changing 
monitoring requirements for chlorite to reflect concern about potential 
acute health effects. Several commenters stated that daily monitoring 
of chlorite would be feasible if an amperometric analytical method 
could be used. Commenters suggested that daily amperometric analyses 
for chlorite be conducted on samples taken from the entrance to the 
distribution system, and that weekly or monthly analyses using ion 
chromatography still be required as a check, because ion chromatography 
is a more accurate analytical method. Commenters noted that daily 
monitoring for chlorite would provide improved operational control of 
plants and reduce the likelihood of systems incurring compliance 
violations.
    Today's rule establishes amperometric titration (Standard Method 
4500-ClO2 E) for daily analyses of chlorite samples taken at 
the entrance to the distribution system, along with monthly (or 
quarterly if reduced, or additional as required), analyses by ion 
chromatography (EPA Methods 300.0 and 300.1) of chlorite samples taken 
from within the distribution system. EPA believes that the ion 
chromatography method, rather than the amperometric method, should be 
used for making chlorite compliance determinations in the distribution 
system due to its greater accuracy. However, the amperometric method is 
sufficient for the purposes of daily monitoring at the entrance to the 
distribution system, which are to significantly aid in proper 
operational control of a treatment plant and to indicate when 
distribution system testing is appropriate. For this reason, only the 
ion chromatographic methods (EPA Method 300.0 and 300.1), and not the 
amperometric titration methods, are approved in today's rule for 
determining compliance with the chlorite MCL.
    A minority of commenters on this issue suggested that the DPD 
method (Standard Method 4500-ClO2 D (APHA 1995)) be approved 
for daily monitoring of chlorite ion levels. EPA has determined that 
the accuracy and precision of the DPD method (Standard Method 4500-
ClO2 D) in the measurement of chlorite are substantially 
worse than with Standard Method 4500-ClO2 E, and are 
insufficient for this method to be used for daily monitoring of 
chlorite. As a consequence, EPA has not approved the DPD method for 
chlorite monitoring in today's rule.
    TOC. EPA received several comments on the 1994 proposal requesting 
approval of Standard Method 5310 B for TOC compliance analysis. 
Commenters stated that newer instrumentation could achieve a detection 
limit of 0.5 mg/L TOC using this method. Following the publication of a 
revised version of Method 5310 B in Standard Methods 19th Edition 
Supplement (APHA 1996) which recognized the capacity of some combustion 
based TOC analyzers to achieve detection limits below 1 mg/L, EPA 
requested comment on approving Standard Method 5310 B, along with 
Standard Methods 5310 C and 5310 D, for the analysis of TOC in the 1997 
DBPR NODA.
    The majority of commenters on TOC analysis urged EPA to approve all 
three methods. Commenters were concerned, though, that because these 
three methods employ different processes to oxidize organic carbon to 
carbon dioxide, results from different TOC analyzers could vary to a 
degree that is of regulatory significance. Specifically, the efficiency 
of oxidation of large organic particles or very large organic molecules 
such as tannins, lignins, and humic acids may be lower with persulfate 
based instruments (APHA 1996). Although available data comparing 
different TOC methods is limited, one study observed a persulfate 
catalytic oxidation technique to underestimate the TOC concentration 
measured by a high temperature catalytic oxidation technique by 3-6% on 
stream water and soil water samples (Kaplan, 1992). Standard Methods 
recommends checking the oxidation efficiency of the instrument with 
model compounds representative of the sample matrix, because many 
factors can influence conversion of organic carbon to carbon dioxide 
(APHA 1996).
    EPA believes that the potential regulatory impact of small 
disparities in oxidation efficiencies between different TOC analyzers 
is minor. Studies using PE samples indicate that for instruments 
calibrated in accordance with the

[[Page 69421]]

procedures specified in Standard Methods (APHA, 1996), the magnitude of 
measurement error due to analytical discrepancies between instruments 
will typically be less than the measurement uncertainty attributed to a 
particular instrument (EPA, 1994c). In addition, EPA anticipates that 
most systems will use a consistent method for TOC analyses and that 
this will assist in minimizing the importance of instrument bias. This 
practice was suggested by several commenters.
    Commenters also suggested that EPA implement a formal certification 
process for laboratories measuring TOC. Some commenters recommended 
that EPA require a laboratory approval process for TOC measurements 
under the Stage 1 DBPR that is similar to what is required under the 
ICR. EPA requires that TOC analyses be conducted by a party approved by 
EPA or the State but not that TOC measurements be subject to the same 
laboratory certification procedures required for the analysis of DBPs. 
However, today's rule contains QC requirements for TOC analyses which 
are in addition to those in Standard Methods. These additional QC 
procedures pertain to sample preservation and holding time, and have 
been found to be effective for TOC analyses under the ICR.
    SUVA. In the 1997 DBPR NODA, EPA solicited comment on a range of 
issues dealing with the determination of SUVA including: analytical 
methods, sampling, sample preparation, filter types, pH, interferences 
to UV, high turbidity waters, quality control, and other issues that 
should be addressed. The Agency requested comment on approving Standard 
Method 5910 B for measuring UV254 and Standard Methods 5310 
B, C, and D, for measuring DOC. In requesting comment on filtration, 
EPA noted that filtration is necessary prior to both UV254 
and DOC analyses in order to eliminate particulate matter and separate 
the operationally defined dissolved organic matter (based on a 0.45 
m-pore-diameter cut-off). However, filtration can also corrupt 
samples through adsorption of carbonaceous material onto the filter or 
its desorption from it (APHA 1996). In addition, EPA requested comment 
on requiring that UV254 and DOC analyses be measured from 
the same sample filtrate.
    The majority of commenters on SUVA analytical methods recommended 
that EPA approve Standard Methods 5310 B, C, and D, for DOC analysis 
and Standard Method 5910 B for UV254 analysis. EPA has 
approved these methods in today's rule. In addition, commenters 
stressed the importance of sample preparation, especially filtration, 
in the measurement of DOC and observed that sufficient washing of 
filters prior to filtration of samples is critical to preventing 
contamination of the samples by organic carbon from the filters. 
Several comments on the 1997 DBPR NODA expressed opposition to a 
requirement that UV254 and DOC analyses be made on the same 
sample filtrate. Commenters stated that this is impractical because UV 
analyses are often conducted at the treatment plant while DOC analyses 
are typically run off-site. Commenters also noted that DOC samples 
should be acid preserved whereas pH adjustment of samples for 
UV254 analysis is improper.
    Today's rule establishes that samples for DOC and UV254 
analyses must be filtered through a 0.45 m-pore-diameter 
filter. EPA does not have specific requirements on the type of filter 
that is used, provided it has a 0.45 m pore-diameter, but will 
provide guidance on this issue in the Guidance Manual for Enhanced 
Coagulation. This manual will be available for public review after 
promulgation of the Stage 1 DBPR. Today's rule addresses filter washing 
prior to analysis by requiring that water passed through the filter 
prior to filtration of the sample serve as the filtered blank. The 
filtered blank must be analyzed using procedures identical to those 
used for analysis of the samples and must meet the following criteria: 
TOC < 0.5 mg/L. These criteria are the maximum allowable background 
concentrations specified for these analyses under the ICR. In the 
Guidance Manual for Enhanced Coagulation, EPA will furnish instructions 
on sample handling and filter washing to assist systems in achieving 
acceptable field reagent blanks.
    Filtration of samples for DOC analysis must be done prior to acid 
preservation, as stipulated in today's rule. This is necessary because 
acidification of the sample to pH < 2 can cause substantial 
precipitation of dissolved organic species. Because biological activity 
will rapidly alter the DOC of a sample that has not been preserved, EPA 
requires that DOC samples be acidified to pH < 2.0 within 48 hours of 
sampling. Consequently, filtration of DOC samples must be done within 
48 hours in order to allow acid preservation within this time period. 
The pH of UV254 samples may not be adjusted. Today's rule 
places a maximum holding time from sampling to analysis of 2 days for 
UV254 samples and 28 days for DOC samples. These holding 
times are the same as those approved for ICR data collection.
    Because the filtration procedures for UV254 and DOC 
samples are largely identical, EPA anticipates that most systems will 
find it economical when determining SUVA to filter one sample. The 
filtrate would then be split into two portions, one of which would be 
used for UV analysis while the other would be acid preserved and used 
for DOC analysis. However, EPA has not included a requirement that the 
DOC and UV254 analyses used in the SUVA determination be 
made on the same sample filtrate. Instead, EPA requires that DOC and 
UV254 samples used to determine a SUVA value must be taken 
at the same time and at the same location.
    In the 1997 DBPR NODA, EPA also observed that because 
disinfectants/oxidants (chlorine, ozone, chlorine dioxide, potassium 
permanganate) typically reduce UV254 without substantially 
impacting DOC, raw water SUVA should be determined on water prior to 
the application of disinfectants/oxidants. If disinfectants/oxidants 
are applied in raw-water transmission lines upstream of the plant, then 
raw water SUVA should be based on a sample collected upstream of the 
point of disinfectant/oxidant addition. For determining settled-water 
SUVA, if the plant applies disinfectants/oxidants prior to the settled 
water sample tap, then settled-water SUVA should be determined in jar 
testing. No commenters were opposed to these provisions and today's 
rule requires that samples used for SUVA determinations be taken from 
water prior to the addition of any oxidants/disinfectants.
    A few commenters stated that SUVA should not be subject to rigorous 
analytical procedures because the application of SUVA in this rule is 
based on a relationship which is largely empirical (i.e. correlations 
between SUVA and TOC removal by coagulation). EPA recognizes the 
empirical nature of this relationship and the variance it has displayed 
in studies. Regulations, however, must address specific SUVA values if 
SUVA is to serve as an alternative compliance parameter. For compliance 
with these regulations to be meaningful, SUVA must be determined 
accurately. Consequently, today's rule requires certain QC procedures 
in the DOC and UV254 analyses that are used to calculate 
SUVA.
    Today's rule establishes the removal of 10 mg/L magnesium hardness 
(as CaCO3) as an alternative performance criterion that systems 
practicing enhanced softening can use to demonstrate compliance with 
the treatment technique requirement for TOC removal. However, EPA did 
not propose methods for the analysis of

[[Page 69422]]

magnesium in drinking water and therefore the final rule does not 
contain any approved methods for magnesium. EPA expects to propose 
magnesium analytical methods to be used for compliance monitoring under 
the Stage 1 DBPR by the end of 1998.
4. Performance Based Measurement Systems
    On October 6, 1997, EPA published a Document of the Agency's intent 
to implement a Performance Based Measurement System (PBMS) in all of 
its programs to the extent feasible (EPA, 1997f). The Agency is 
currently determining the specifics steps necessary to implement PBMS 
in its programs and preparing an implementation plan. Final decisions 
have not yet been made concerning the implementation of PBMS in 
drinking water programs. However, EPA is currently evaluating what 
relevant performance characteristics should be specified for monitoring 
methods used in the drinking water programs under a PBMS approach to 
ensure adequate data quality. EPA would then specify performance 
requirements in its regulations to ensure that any method used for 
determination of a regulated analyte is at least equivalent to the 
performance achieved by other currently approved methods. EPA expects 
to publish its PBMS implementation strategy for water programs in the 
Federal Register by the end of calendar year 1998.
    Once EPA has made its final determinations regarding implementation 
of PBMS in programs under the Safe Drinking Water Act, EPA would 
incorporate specific provisions of PBMS into its regulations, which may 
include specification of the performance characteristics for 
measurement of regulated contaminants in the drinking water program 
regulations.

H. Monitoring Requirements

1. Today's Rule
    Today's rule establishes monitoring requirements to support 
implementation of the enhanced coagulation and enhanced softening 
treatment technique, implementation of new MCLs for TTHM, HAA5, 
bromate, and chlorite, and implementation of MRDLs for chlorine, 
chloramines, and chlorine dioxide. Monitoring for DBPs, disinfectant 
residuals, and TOC must be conducted during normal operating 
conditions. Failure to monitor in accordance with the monitoring plan 
is a monitoring violation. Where compliance is based on a running 
annual average of monthly or quarterly samples or averages and the 
system's failure to monitor makes it impossible to determine compliance 
with MCLs or MRDLs, this failure to monitor will be treated as a 
violation.
    Tables III-3 and III-4 below summarize routine and reduced 
monitoring requirements of today's rule.

                                                    Table III-3.--Routine Monitoring Requirements \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                              Large surface systems  Small surface systems    Large ground water     Small ground water
      Requirement (reference)         Location for sampling            \2\                    \2\                systems \3\            systems \3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
TOC and Alkalinity (141.132(d)(1)).  Source Water \4\......  1sample/month/plant     1 sample/month/        NA...................  NA.
                                                              \3\.                    plant\3\.
                                     Only required for
                                      plants with
                                      conventional
                                      filtration treatment.
TTHMs and HAA5 (141.132(b)(1)(i))..  25% in dist sys at max  4/plant/quarter.......  1/plant/quarter\5\...  1/plant/quarter \6\..  1/plant/year 5,6
                                      res time, 75% at dist
                                      sys representative
                                      locations.
                                                                                     at maximum residence   at maximum residence   at maximum residence
                                                                                      time.                  time.                  time.
                                                                                     if pop.<500, then 1/                          during warmest month.
                                                                                      plant/yr \8\.
                                                                                     during warmest month.
Bromate \7\ (141.132(b)(3)(i)).....  Dist sys entrance       1/month/trt plant       1/month/trt plant      1/month/trt plant      1/month/trt plant
                                      point.                  using O3.               using O3.              using O3.              using O3.
Chlorite\8\ (daily)                  Dist sys entrance       Daily/trt plant using   Daily/trt plant using  Daily/trt/plant using
 (141.132(b)(2)(i)(A)).               point.                  CIO2.                   CIO2.                  CIO2.
Chlorite\8\ (monthly)                Dist sys: 1 near first  3 sample set/month....  3 sample set/month...  3 sample set/month...  3 sample set/month.
 141.132(b)(2)(i)(B)).                cust, 1 in dist sys
                                      middle, 1 at max res
                                      time.
Chlorine and chloramines             Same points as total    Same times as total     Same times as total    Same times as total    Same times as total
 (141.132(c)(1)(i)).                  coliform in TCR.        coliform in TCR.        coliform in TCR.       coliform in TCR.       coliform in TCR.
Chlorine dioxide\8\                  Dist sys entrance        Daily/trt plant using   Daily/trt plant        Daily/trt plant        Daily/trt plant
 (141.132(c)(2)(i)).                  point.                  CIO2.                   using CIO2.            using CIO2.            using CIO.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Samples must be taken during representative operating conditions. Provisions for reduced monitoring shown elsewhere.
\2\ Large surface (subpart H) systems serve 10,000 or more persons. Small surface (subpart H) systems serve fewer than 10,000 persons.
\3\ Large systems using ground water not under the direct influence of surface water serve 10,000 or more persons. Small systems using ground water not
  under the direct influence of surface water serve fewer than 10,000 persons.
\4\ Subpart H systems which use conventional filtration treatment (defined in section 141.2) must monitor 1) source water TOC prior to any treatment and
  2) treated TOC at the same time; these two samples are called paired samples. Systems must take a source water alkalinity sample at the same time.
\5\ If the annual monitoring result exceeds the MCL, the system must increase monitoring frequency to 1/plant/quarter. Compliance determinations will be
  based on the running annual average of quarterly monitoring results.

[[Page 69423]]

 
\6\ Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment plant for determining the minimum number of
  samples.
\7\ Only required for systems using ozone for oxidation or disinfection.
\8\ Only required for systems using chlorine dioxide for oxidation or disinfection. Additional chlorite monitoring required if daily sample exceeds MCL.
  Additional chlorine dioxide monitoring requirements apply if any chlorine dioxide sample exceeds the MRDL.


                                Table III-4.--Reduced Monitoring Requirements \1\
----------------------------------------------------------------------------------------------------------------
                                         Location for reduced    Reduced monitoring frequency and prerequisites
       Requirement (reference)                 sampling                                \2\
----------------------------------------------------------------------------------------------------------------
TOC and Alkalinity (141.132(d)(2))...  Paired samples \3\.....  Subpart H systems-reduced to 1 paired sample/
                                                                 plant/quarter if 1) avg TOC < 2.0 mg/l for 2
                                                                 years or 2) avg TOC < 1.0 mg/l for 1 year.
TTHMs and HAA5s (141.132(b)(1)(ii))..  In dist sys at point     Monitoring cannot be reduced if subpart H system
                                        with max res time.       source water TOC > 4.0 mg/l.
                                                                Subpart H systems serving 10,000 or more-reduced
                                                                 to 1/plant/qtr if 1) system has completed at
                                                                 least 1 yr of routine monitoring and 2) both
                                                                 TTHM and HAA5 running annual averages are no
                                                                 more than 40 g/l and 30 g/l,
                                                                 respectively.
                                                                Subpart H systems serving <10,000 and ground
                                                                 water systems \4\ serving 10,000 or more-
                                                                 reduced to 1/plant/yr if 1) system has
                                                                 completed at least 1 yr of routine monitoring
                                                                 and 2) both TTHM and HAA5 running annual
                                                                 averages are no more than 40 g/l and
                                                                 30 g/l, respectively. Samples must be
                                                                 taken during month of warmest water
                                                                 temperature. Subpart H systems serving <500 may
                                                                 not reduce monitoring to less than 1/plant/yr.
                                                                Groundwater systems \6\ serving<10,000-reduced
                                                                 to 1/plant/3yr if 1) system has completed at
                                                                 least 2 yr of routine monitoring and both TTHM
                                                                 and HAA5 running annual averages are no more
                                                                 than 40 g/l and 30 g/l,
                                                                 respectively or 2) system has completed at
                                                                 least 1 yr of routine monitoring and both TTHM
                                                                 and HAA5 annual samples are no more than 20
                                                                 g/l and 15 g/l, respectively.
                                                                 Samples must be taken during month of warmest
                                                                 water temperature.
Bromate \5\ (141.132(b)(3)(ii))......  Dist sys entrance point  1/qtr/trt plant using O3, if system demonstrates
                                                                 1) avg raw water bromide <0.05 mg/l (based on
                                                                 annual avg of monthly samples).
Chlorite \6\ (141.132(b)(2)(iii))....  Dist sys: 1 near first   Systems may reduce routine distribution system
                                        cust, 1 in dist sys      monitoring from monthly to quarterly if the
                                        middle, 1 at max res     chlorite concentration in all samples taken in
                                        time.                    the distribution system is below 1.0 mg/L for a
                                                                 period of one year; 3 samples per quarter.
Chlorine, chlorine dioxide \6\,        NA.....................  Monitoring may not be reduced.
 chloramines (141.132(c)(2)(ii) and
 (c)(2)(iii).
----------------------------------------------------------------------------------------------------------------
\1\ Samples must be taken during representative operating conditions. Provisions for routine monitoring shown
  elsewhere.
\2\ Requirements for cancellation of reduced monitoring are found in the regulation.
\3\ Subpart H systems which use conventional filtration treatment (defined in Section 141.2) must monitor 1)
  source water TOC prior to any treatment and 2) treated TOC before continuous disinfection (except that systems
  using ozone followed by biological filtration may sample after biological filtration) at the same time; these
  two samples are called paired samples.
\4\ Multiple wells drawing water from a single aquifer may, with State approval, be considered one treatment
  plant for determining the minimum number of samples.
\5\ Only required for systems using ozone for oxidation or disinfection.
\6\ Only required for systems using chlorine dioxide for oxidation or disinfection.

    The formation rate of DBPs is affected by 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, today's rule 
specifies the points in the distribution system (and, in some cases, 
the time) where samples must be taken. For purposes of this regulation, 
multiple wells drawing raw water from a single aquifer may, with State 
approval, be considered one plant for determining the minimum number of 
samples.
    TTHM and HAA5. Any system may take samples in excess of the 
required frequency. In such cases, at least 25 percent of all samples 
collected each quarter must be taken at locations within the 
distribution system that represent the maximum residence time of the 
water in the system. The remaining samples must be taken at locations 
representative of at least average residence time in the distribution 
system.
    Subpart H Systems Serving 10,000 or More People. Routine 
Monitoring: CWSs and NTNCWSs using surface water (or ground water under 
direct influence of surface water) (Subpart H systems) that treat their 
water with a chemical disinfectant and serve 10,000 or more people must 
routinely take four water samples each quarter for both TTHMs and HAA5 
for each treatment plant in the system. At least 25 percent of the 
samples must be taken at the point of maximum residence time in the 
distribution system. The remaining samples must be taken at 
representative points in the distribution system. This monitoring 
frequency is the same as the frequency required under the current TTHM 
rule (Sec. 141.30).
    Reduced Monitoring: To qualify for reduced monitoring, systems must 
meet certain prerequisites (see Figure III-1). Systems eligible for 
reduced monitoring may reduce the monitoring frequency for TTHMs and 
HAA5 to one sample per treatment plant per quarter. Systems on a 
reduced monitoring schedule may remain on that reduced schedule as long 
as the average of all samples taken in the year 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 system to 
routine monitoring at the State's discretion.

[[Page 69424]]



 Figure III-1.--Eligibility for Reduced TTHM and HAA5 Monitoring: Ground
    Water Systems Serving 10,000 or More People and Subpart H Systems
                       Serving 500 or More People
------------------------------------------------------------------------
 
-------------------------------------------------------------------------
Ground water systems serving 10,000 or more people, and Subpart H
 systems serving 500 or more people, may reduce monitoring of TTHMs and
 HAA5 if they meet all of the following conditions:
    --The annual average for TTHMs is no more than 0.040 mg/L.
    --The annual average for HAA5 is no more than 0.030 mg/L.
    --At least one year of routine monitoring has been completed.
    --Annual average source water TOC level is no more than 4.0 mg/L
     prior to treatment (applies to Subpart H systems only).
------------------------------------------------------------------------

    Compliance Determination: A public water system (PWS) is in 
compliance with the MCL when the running annual arithmetic average of 
quarterly averages of all samples, computed quarterly, is less than or 
equal to the MCL. If the running annual average computed for any 
quarter exceeds the MCL, the system is out of compliance.
    Subpart H Systems Serving 500 to 9,999 People. Routine Monitoring: 
Systems are required to take one water sample each quarter for each 
treatment plant in the system. Samples must be taken at the point of 
maximum residence time in the distribution system.
    Reduced Monitoring: To qualify for reduced monitoring, systems must 
meet certain prerequisites (see Figure III-1). Systems eligible for 
reduced monitoring may reduce the monitoring frequency for TTHMs and 
HAA5 to one sample per treatment plant per year. Sample must be taken 
at a distribution system location reflecting maximum residence time and 
during the month of warmest water temperature. Systems on a reduced 
monitoring schedule may remain on that reduced schedule as long as the 
average of all samples taken in the year 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 system to routine 
monitoring at the State's discretion.
    Compliance Determination: A PWS is in compliance with the MCL for 
TTHM and HAA5 when the annual average of all samples, taken that year, 
is less than or equal to the MCL. If the average for these samples 
exceeds the MCL, the system is out of compliance.
    Subpart H Systems Serving Fewer than 500 People. Routine 
Monitoring: Subpart H systems serving fewer than 500 people are 
required to take one sample per year for each treatment plant in the 
system. The sample must be taken at the point of maximum residence time 
in the distribution system during the month of warmest water 
temperature. If the annual sample exceeds the MCL, the system must 
increase monitoring to one sample per treatment plant per quarter, 
taken at the point of maximum residence time in the distribution 
system.
    Reduced Monitoring: These systems may not reduce monitoring. 
Systems on increased monitoring may return to routine monitoring if the 
annual average of quarterly samples is 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 average of annual samples, if additional sampling is 
conducted) is less than or equal to the MCL. If the annual sample 
exceeds the MCL, the system must increase monitoring to one sample per 
treatment plant per quarter. If the running annual average of the 
quarterly samples then exceeds the MCL, the system is out of 
compliance.
    Ground Water Systems Serving 10,000 or More People. Routine 
Monitoring: CWSs and NTNCWSs using only ground water sources not under 
the direct influence of surface water that treat their water with a 
chemical disinfectant and serve 10,000 or more people are required to 
take one water sample each quarter for each treatment plant in the 
system. Samples must be taken at points that represent the maximum 
residence time in the distribution system.
    Reduced Monitoring: To qualify for reduced monitoring, systems must 
meet certain prerequisites (see Figure III-1). Systems eligible for 
reduced monitoring may reduce the monitoring frequency to one sample 
per treatment plant per year. Sample must be taken at a distribution 
system location reflecting maximum residence time and during the month 
of warmest water temperature. Systems on a reduced monitoring schedule 
may remain on that reduced schedule as long as the average of all 
samples taken in the year 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 system to routine monitoring at 
the State's discretion.
    Compliance Determination: A PWS is in compliance with the MCL when 
the running arithmetic annual average of quarterly averages of all 
samples, computed quarterly, is less than or equal to the MCL. If the 
running annual average for any quarter exceeds the MCL, the system is 
out of compliance.
    Ground Water Systems Serving Fewer than 10,000 People Routine 
Monitoring: CWSs and NTNCWSs using only ground water sources not under 
the direct influence of surface water that treat their water with a 
chemical disinfectant and serve fewer than 10,000 people are required 
to sample once per year for each treatment plant in the system. The 
sample must be taken at the point of maximum residence time in the 
distribution system during the month of warmest water temperature. If 
the sample (or the average of annual samples if more than one sample is 
taken) exceeds the MCL, the system must increase monitoring to one 
sample per treatment plant per quarter.
    Reduced Monitoring: To qualify for reduced monitoring, systems must 
meet certain prerequisites (see Figure III-2). Systems eligible for 
reduced monitoring may reduce the monitoring frequency for TTHMs and 
HAA5 to one sample per three-year monitoring cycle. Sample must be 
taken at a distribution system location reflecting maximum residence 
time and during the month of warmest water temperature. Systems on a 
reduced monitoring schedule may remain on that reduced schedule as long 
as the average of all samples taken in the year 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 resume routine monitoring. Systems on increased monitoring 
may return to routine monitoring if the annual average of quarterly 
samples is 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 average of annual samples) is less than or equal to the MCL.

[[Page 69425]]



 Figure III-2.--Eligibility for Reduced TTHM and HAA5 Monitoring: Ground
             Water Systems Serving Fewer than 10,000 People
------------------------------------------------------------------------
 
-------------------------------------------------------------------------
Systems using ground water not under the direct influence of surface
 water that serve fewer than 10,000 people may reduce monitoring for
 TTHMs and HAA5 if they meet either of the following conditions:
1. The average of two consecutive annual samples for TTHMs is no more
 than 0.040 mg/L, the average of two consecutive annual samples for HAA5
 is no more than 0.030 mg/L, and at least two years of routine
 monitoring has been completed.
2. The annual sample for TTHMs is no more than 0.020 mg/L, the annual
 sample for HAA5 is no more than 0.015 mg/L, and at least one year of
 routine monitoring has been completed.
------------------------------------------------------------------------

    Chlorite. Routine Monitoring: CWSs and NTNCWSs using chlorine 
dioxide for disinfection or oxidation are required to conduct sampling 
for chlorite both daily at the entrance to the distribution system and 
monthly within the distribution system. Additional distribution system 
monitoring may be required, and distribution system monitoring may be 
reduced if certain conditions are met. This monitoring is described 
below.
    Routine Monthly Monitoring--Systems are required to take a three 
sample set each month in the distribution system. One sample must be 
taken at each of the following locations: (1) as close as possible to 
the first customer, (2) in a location representative of average 
residence time, and (3) as close as possible to the end of the 
distribution system (reflecting maximum residence time in the 
distribution system). As described elsewhere in this document, all 
samples taken in the distribution system must be analyzed by ion 
chromatography (Methods 300.0 and 300.1).
    Routine Daily Monitoring--Systems must take one sample each day at 
the entrance to the distribution system. As described elsewhere in this 
document (section III.G), samples taken at the distribution system 
entrance may be analyzed by amperometric titration (Method 4500-
ClO2 E). If the chlorite MCL is exceeded at the entrance to 
the distribution system, the system is not out of compliance. However, 
the system must carry out addition monitoring as described in the 
following paragraph.
    Additional Monitoring: On any day when the chlorite concentration 
measured at the entrance to the distribution system exceeds the 
chlorite MCL (1.0 mg/L), the system is required to take a three sample 
set in the distribution system on the following day, at the locations 
specified for routine monthly monitoring. If the system is required to 
conduct distribution system monitoring as a result of having exceeded 
the chlorite MCL at the entrance to the distribution system, and the 
average of the three samples taken in the distribution system is below 
1.0 mg/L, the system will have satisfied its routine monthly monitoring 
requirement for that month. Further distribution system monitoring will 
not be required in that month unless the chlorite concentration at the 
entrance to the distribution system again exceeds 1.0 mg/L.
    Reduced Monitoring: Systems may reduce routine distribution system 
monitoring for chlorite from monthly to quarterly if the chlorite 
concentration in all samples taken in the distribution system is below 
1.0 mg/L for a period of one year and the system has not been required 
to conduct any additional monitoring. Systems that qualify for reduced 
monitoring must continue to conduct daily monitoring at the entrance to 
the distribution system. If the chlorite concentration at the entrance 
to the distribution system exceeds 1.0 mg/L, the system must resume 
routine monthly monitoring.
    Compliance Determination: A PWS is out of compliance with the 
chlorite MCL when the arithmetic average concentration of any three 
sample set taken in the distribution system is greater than 1.0 mg/L.
    Bromate. Routine Monitoring: CWSs and NTNCWSs using ozone for 
disinfection or oxidation are required to take at least one sample per 
month for each treatment plant in the system using ozone. The sample 
must be taken at the entrance to the distribution system when the 
ozonation system is operating under normal conditions.
    Reduced Monitoring: Systems may reduce monitoring from monthly to 
once per quarter if the system demonstrates that the annual average raw 
water bromide concentration is less than 0.05 mg/L, based upon monthly 
measurements for one year.
    Compliance Determination: A PWS is in compliance if the running 
annual arithmetic average of samples, computed quarterly, is less than 
or equal to the MCL.
    Chlorine. Routine Monitoring: As a minimum, CWSs and NTNCWSs must 
measure the residual disinfectant level (as either free chlorine or 
total chlorine) at the same points in the distribution system and at 
the same time as total coliforms, as specified in Sec. 141.21. Subpart 
H systems may use the results of residual disinfectant concentration 
sampling done under the SWTR (Sec. 141.74(b)(6)(i) for unfiltered 
systems, Sec. 141.74(c)(3)(i) for systems that filter) in lieu of 
taking separate samples.
    Reduced Monitoring: Monitoring for chlorine may not be reduced.
    Compliance Determination: A PWS is in compliance with the MRDL when 
the running annual arithmetic average of monthly averages of all 
samples, computed quarterly, is less than or equal to the MRDL. 
Notwithstanding the MRDL, operators may increase residual chlorine 
levels in the distribution system to a level and for a time necessary 
to protect public health to address specific microbiological 
contamination problems (e.g., including distribution line breaks, storm 
runoff events, source water contamination, or cross-connections).
    Chloramines. Routine Monitoring: As a minimum, CWSs and NTNCWSs 
must measure the residual disinfectant level (as either total chlorine 
or combined chlorine) at the same points in the distribution system and 
at the same time as total coliforms, as specified in Sec. 141.21. 
Subpart H systems may use the results of residual disinfectant 
concentration sampling done under the SWTR (Sec. 141.74(b)(6) for 
unfiltered systems, Sec. 141.74(c)(3) for systems that filter) in lieu 
of taking separate samples.
    Reduced Monitoring: Monitoring for chloramines may not be reduced.
    Compliance Determination: A PWS is in compliance with the MRDL when 
the running annual arithmetic average of monthly averages of all 
samples, computed quarterly, is less than or equal to the MRDL. 
Notwithstanding the MRDL, operators may increase residual chloramine 
levels in the distribution system to a level and for a time necessary 
to protect public health to address specific microbiological 
contamination problems (e.g., including distribution line breaks, storm 
runoff events, source water contamination, or cross-connections).
    Chlorine Dioxide Routine Monitoring: CWSs, NTNCWSs, and TNCWSs must 
monitor for chlorine dioxide only if chlorine dioxide is used by the 
system for disinfection or oxidation. If monitoring is required, 
systems must take daily samples at the entrance to the

[[Page 69426]]

distribution system. If the MRDL (0.8 mg/L) is exceeded, the system 
must conduct additional monitoring.
    Additional Monitoring: If any daily sample taken at the entrance to 
the distribution system exceeds the MRDL, the system is required to 
take three additional samples in the distribution system on the next 
day. Samples must be taken at the following locations.
    Systems using chlorine as a residual disinfectant and operating 
booster chlorination stations after the first customer--These systems 
must take three samples in the distribution system: one as close as 
possible to the first customer, one in a location representative of 
average residence time, and one as close as possible to the end of the 
distribution system (reflecting maximum residence time in the 
distribution system).
    Systems using chlorine dioxide or chloramines as a residual 
disinfectant or chlorine as a residual disinfectant and not operating 
booster chlorination stations after the first customer--These systems 
must take three samples in the distribution system as close as possible 
to the first customer at intervals of not less than six hours.
    Reduced Monitoring: Monitoring for chlorine dioxide may not be 
reduced.
    Compliance Determination: Acute violations--If any daily sample 
taken at the entrance to the distribution system exceeds the MRDL and 
if, on the following day, one or more of the three samples taken in the 
distribution system exceeds the MRDL, the system will be in acute 
violation of the MRDL and must issue the required acute public 
notification. Failure to monitor in the distribution system on the day 
following an exceedance of the chlorine dioxide MRDL shall also be 
considered an acute MRDL violation.
    Nonacute violations--If any two consecutive daily samples taken at 
the entrance to the distribution system exceed the MRDL, but none of 
the samples taken in the distribution system exceed the MRDL, the 
system will be in nonacute violation of the MRDL. Failure to monitor at 
the entrance to the distribution system on the day following an 
exceedance of the chlorine dioxide MRDL shall also be considered a 
nonacute MRDL violation.
    Important Note: Unlike chlorine and chloramines, the MRDL for 
chlorine dioxide may not be exceeded for short periods of time to 
address specific microbiological contamination problems.
    TOC. Routine Monitoring: CWSs and NTNCWSs which use conventional 
filtration treatment must monitor each treatment plant water source for 
TOC on a monthly basis, with samples taken in both the source water 
prior to any treatment and in the treated water no later than the point 
of combined filter effluent turbidity monitoring. At the same time, 
systems must monitor for source water alkalinity.
    Reduced Monitoring: Subpart H systems with an average treated water 
TOC of less than 2.0 mg/L for two consecutive years, or less than 1.0 
mg/L for one year, may reduce monitoring for both TOC and alkalinity to 
one paired sample per plant per quarter.
    Compliance Determination: Compliance criteria for TOC are dependent 
upon a variety of factors and is discussed elsewhere in this rule.
2. Background and Analysis
    The monitoring requirements in today's rule are the same as those 
in the 1994 proposed rule, with the exception of requirements for 
bromide monitoring and chlorite.
    Bromide Monitoring for Reduced Bromate Monitoring. The 1994 
proposal included a provision for reduced bromate monitoring for 
utilities with source water bromide concentrations less than 0.05 mg/L. 
EPA believes there is a very small likelihood that systems using ozone 
will exceed the bromate MCL if source water bromide concentrations are 
below this level. The provision did not specify a bromide monitoring 
frequency, however. Today's rule allows utilities to reduce bromate 
monitoring from monthly to once per quarter if the system demonstrates, 
based on representative monthly samples over the course of a year, that 
the average raw water bromide concentration is less than 0.05 mg/L.
    Chlorite Monitoring. The proposed rule required treatment plants 
using chlorine dioxide to monitor for chlorite ion by taking a three 
sample set in the distribution system, once per month, and to analyze 
these samples using ion chromatography. However, the proposal states 
that after the Negotiating Committee had agreed to the above monitoring 
scheme for chlorite at its last meeting in June, 1993, EPA's Reference 
Dose Committee met and determined a different toxicological endpoint 
for chlorite, based on the identification of neurobehavioral effects. 
In light of this finding, EPA asserted that it did not believe the 
proposed monthly monitoring requirement for chlorite was sufficiently 
protective of public health. Following the proposed rule, EPA acquired 
additional information on chlorite toxicity, including the results of a 
two-generation study sponsored by the CMA. This additional information, 
discussed elsewhere in this document (III.A.7), supported EPA's finding 
of neurobehavioral health effects resulting from chlorite, along with 
the rationale for daily monitoring at the entrance to the distribution 
system as a trigger for further compliance monitoring in the 
distribution system.

3. Summary of Comments

    TOC. Many commenters expressed confusion regarding the raw and 
finished water TOC monitoring scheme and their relationship to 
compliance calculations. Commenters noted, correctly, that changes in 
alkalinity and TOC level can move the utility to a different box of the 
TOC removal matrix, and questioned whether this would affect requisite 
monitoring. As in the proposal, moving to a different box of the matrix 
will not affect monitoring requirements. Utilities are required to take 
a minimum of one paired (raw and finished water) TOC sample per month. 
Commenters were also concerned that the TOC monitoring provisions would 
limit their ability to take additional TOC samples for operational 
control. This concern is unfounded; EPA recommends in the Enhanced 
Coagulation and Enhanced Precipitative Softening Guidance Manual that 
utilities take as many TOC samples as necessary to maintain proper 
operational control. EPA also recommends that TOC compliance samples, 
as opposed to operational samples, be taken on a constant schedule or 
be identified one month prior to the samples being taken. This will 
allow utilities to take numerous operational samples and still provide 
for unbiased compliance sampling. Systems may use their sampling plans 
for this purpose.
    Chlorite. In the proposal, EPA solicited comment on changing the 
frequency and location of chlorite monitoring in consideration of 
potential acute health effects. Commenters stated that daily monitoring 
of chlorite would be feasible if amperometric titration were allowed as 
an analytical method. Commenters recommended that daily amperometric 
analyses for chlorite be conducted on samples taken from the entrance 
to the distribution system, and that weekly or monthly analyses using 
ion chromatography still be required as a check since ion 
chromatography is a more accurate analytical method. Several comments 
stated that daily monitoring for chlorite would improve operational 
control of plants and decrease the probability of a PWS exceeding the 
chlorite MCL in the distribution system. However, commenters requested 
that if daily monitoring for chlorite were to be

[[Page 69427]]

required, a provision for reduced chlorite monitoring be included as 
well.
    In response to these comments, today's rule requires treatment 
plants using chlorine dioxide to conduct daily monitoring for chlorite 
by taking one sample at the entrance to the distribution system. This 
sample may be measured using amperometric titration (Standard Method 
4500-ClO 2 E). Treatment plants are also required to take a 
three sample set from the distribution system once per month, as was 
proposed in 1994. In addition, today's rule requires that on any day 
that the concentration of chlorite measured at the distribution system 
entrance exceeds the MCL, the treatment plant must take a three sample 
set in the distribution system on the following day. All samples taken 
in the distribution system must be analyzed by ion chromatography 
(Method 300.0 or 300.1).
    EPA recommends that treatment plants keep chlorite levels below 1.0 
mg/L and believes that if treatment plants exceed the MCL in finished 
water, immediate distribution system testing is warranted to ensure 
that chlorite levels are below 1.0 mg/L. EPA has not, however, changed 
the compliance determination for chlorite from the 1994 proposed rule. 
Compliance is still based on the average of three sample sets taken in 
the distribution system. The results of daily monitoring do not serve 
as a compliance violation; rather, they can only trigger immediate 
distribution system monitoring. Moreover, if the treatment plant is 
required to take distribution system samples by the results of daily 
monitoring and the average chlorite concentration in the three 
distribution system samples is below the MCL, then that sampling will 
meet the treatment plant's requirement for routine monthly monitoring 
in the distribution system for that month. Today's rule also includes a 
provision for reduced chlorite monitoring. Treatment plants may reduce 
routine distribution system monitoring for chlorite from monthly to 
quarterly if the chlorite concentration in all samples both at the 
entrance to the distribution system and within the distribution system 
are below 1.0 mg/L for a period of one year.
    In summary, after review of all public comments and associated 
data, EPA believes that these provisions for chlorite monitoring will 
be both feasible for treatment plants and provide a level of protection 
to public health commensurate with the toxic effects associated with 
chlorite.

I. Compliance Schedules

1. Today's Rule
    Today's action establishes revised compliance deadlines for States 
to adopt and for public water systems to implement the requirements in 
this rulemaking. Central to the determination of these deadlines are 
the principles of simultaneous compliance between the Stage 1 DBPR and 
the corresponding rules (Interim Enhanced Surface Water Treatment Rule, 
Long Term Enhanced Surface Water Treatment Rule, and Ground Water Rule) 
to ensure continued microbial protection, and minimization of risk-risk 
tradeoffs. These deadlines also reflect new legislative provisions 
enacted as part of 1996 SDWA amendments. Section 1412 (b)(10) of the 
SDWA as amended provides PWSs must comply with new regulatory 
requirements 36 months after promulgation (unless EPA or a State 
determines that an earlier time is practicable or that additional time 
up to two years is necessary for capital improvements). In addition, 
Section 1413(a)(1) provides that States have 24 instead of the previous 
18 months from promulgation to adopt new drinking water standards.
    Applying the 1996 SDWA Amendments to today's action, this 
rulemaking provides that States have two years from promulgation to 
adopt and implement the requirements of this regulation. Simultaneous 
compliance will be achieved as follows.
    Subpart H water systems covered by today's rule that serve a 
population of 10,000 or more generally have three years from 
promulgation to comply with all requirements of this rule. In cases 
where capital improvements are needed to comply with the rule, States 
may grant such systems up to an additional two years to comply. These 
deadlines were consistent with those for the IESWTR.
    Subpart H systems that serve a population of less than 10,000 and 
all ground water systems will be required to comply with applicable 
Stage 1 DBPR requirements within five years from promulgation. Since 
the Long Term Enhanced Surface Water Treatment Rule (LT1) requirements 
that apply to systems under 10,000 and the Ground Water Rule are 
scheduled to be promulgated two years after today's rule or in November 
2000, the net result of this staggered deadline is that these systems 
will be required to comply with both Stage 1 DBPR and LT1/GWR 
requirements three years after promulgation of LT1/GWR at the same end 
date of November 2003. For reasons discussed in more detail below, EPA 
believes this is both consistent with the requirements of section 
1412(b)(10) as well as with legislative history affirming the Reg. Neg. 
objectives of simultaneous compliance and minimization of risk-risk 
tradeoff.
2. Background and Analysis
    The background, factors, and competing concerns that EPA considered 
in developing the compliance deadlines in today's rule are explained in 
detail in both the Agency's IESWTR and Stage 1 DBPR November 1997 
NODAs. As explained in those NODAs, EPA identified four options to 
implement the requirements of the 1996 SDWA Amendments. The 
requirements outlined above reflect the fourth option that EPA 
requested comment upon in November 1997.
    By way of background, the SDWA 1996 Amendments affirmed several key 
principles underlying the M-DBP compliance strategy developed by EPA 
and stakeholders as part of the 1992 regulatory negotiation process. 
First, under Section 1412(b)(5)(A), Congress recognized the critical 
importance of addressing risk/risk tradeoffs in establishing drinking 
water standards and gave EPA the authority to take such risks into 
consideration in setting MCL or treatment technique requirements. The 
technical concerns and policy objectives underlying M/DBP risk/risk 
tradeoffs are referred to in the initial sections of today's rule and 
have remained a key consideration in EPA's development of appropriate 
compliance requirements. Second, Congress explicitly adopted the phased 
M-DBP regulatory development schedule developed by the Negotiating 
Committee. Section 1412(b)(2)(C) requires that the M/DBP standard 
setting intervals laid out in EPA's proposed ICR rule be maintained 
even if promulgation of one of the M-DBPRs is delayed. As explained in 
the 1997 NODA, this phased or staggered regulatory schedule was 
specifically designed as a tool to minimize risk/risk tradeoff. A 
central component of this approach was the concept of ``simultaneous 
compliance'', which provides that a PWS must comply with new microbial 
and DBP requirements at the same time to assure that in meeting a set 
of new requirements in one area, a facility does not inadvertently 
increase the risk (i.e., the risk ``tradeoff'') in the other area.
    A complicating factor that EPA took into account in developing 
today's deadlines is that the SDWA 1996 Amendments changed two 
statutory provisions that elements of the 1992

[[Page 69428]]

Negotiated Rulemaking Agreement were based upon. The 1994 Stage 1 DBPR 
and ICR proposals provided that 18 months after promulgation large PWS 
would comply with the rules and States would adopt and implement the 
new requirements. As noted above, Section 1412(b)(10) of the SDWA as 
amended now provides that drinking water rules shall become effective 
36 months after promulgation (unless the Administrator determines that 
an earlier time is practicable or that additional time for capital 
improvements is necessary--up to two years). In addition, Section 
1413(a)(1) now provides that States have 24 instead of the previous 18 
months to adopt new drinking water standards that have been promulgated 
by EPA.
    Today's compliance deadline requirements reflect the principle of 
simultaneous compliance and the concern with risk/risk tradeoffs. 
Subpart H systems serving a population of at least 10,000 will be 
required to comply with the key provisions of this rule on the same 
schedule as they will be required to comply with the parallel 
requirements of the accompanying IESWTR that is also included in 
today's Federal Register.
    With regard to subpart H systems serving fewer than 10,000, EPA 
believes that providing a five year compliance period under Stage 1 
DBPR is appropriate and warranted under section 1412(b)(10), which 
expressly allows five years where necessary for capital improvements. 
As discussed in more detail in the 1997 IESWTR NODA, capital 
improvements require, of necessity, preliminary planning and 
evaluation. An essential prerequisite of such planning is a clear 
understanding of final compliance requirements that must be met. In the 
case of the staggered M/DBP regulatory schedule established as part of 
the 1996 SDWA Amendments, LT1 microbial requirements for systems under 
10,000 are required to be promulgated two years after the final Stage 1 
DBPR. As a result, small systems will not even know what their final 
combined compliance obligations are until promulgation of the LT 1 
rule. Thus, an additional two year period reflecting the two year Stage 
1 DBPR/LT 1 regulatory development interval established by Congress is 
required to allow for the preliminary planning and design steps which 
are inherent in any capital improvement process.
    In the case of ground water systems, the statutory deadline for 
promulgation of the GWR is May 2002. However, EPA intends to promulgate 
this rule by November 2000, in order to allow three years for 
compliance and still ensure simultaneous compliance by ground water 
systems with the Stage 1 DBPR and the GWR. As in the case of subpart H 
systems serving fewer than 10,000, system operators will not know until 
November 2000 what the final compliance requirements for both rules 
are. EPA thus believes it appropriate to grant the additional two years 
for compliance with the Stage 1 DBPR allowed by the statute.
    EPA has been very successful in meeting all of the new statutory 
deadlines and is on track for the LT1 Rule and GWR. While EPA fully 
intends to meet the schedule discussed earlier, if those rules are 
delayed the Agency will evaluate all available options to protect 
against unacceptable risk-risk trade-offs. Part of this effort is the 
extensive outreach to systems already underway to fully inform water 
supplies of the likely elements in the upcoming rules. In addition, EPA 
would consider including provisions for streamlined variance and/or 
exemption processing in these rules if they were delayed, in order to 
enhance State flexibility in ensuring that compliance with the Stage 1 
DBPR is not required before the corresponding microbial protection 
rule.
    Under today's Stage 1 DBPR, EPA has already provided small subpart 
H systems and ground water systems the two-year extension for capital 
improvements since these systems will not know with certainty until 
November 2000 if capital improvements will be needed for simultaneous 
compliance with the Stage 1 DBPR and LT1/GWR. States considering 
whether to grant a two-year capital improvement extension for 
compliance with the GWR or LT1 will also need to consider the impact of 
such extensions on compliance with today's rule, given that a similar 
extension for capital improvement has already been provided in the 
initial compliance schedule for the Stage 1 DBPR. EPA believes, 
however, that these systems will generally not require extensive 
capital improvements that take longer than three years to install to 
meet Stage 1 DBPR, GWR, and LT1 requirements, or will require no 
capital improvements at all. However if needed, EPA will work with 
States and utilities to address systems that require time beyond 
November 2003 to comply. This strategy may include exemptions.
    In addition, EPA will provide guidance and technical assistance to 
States and systems to facilitate timely compliance with both DBP and 
microbial requirements. EPA will request comment on how best to do this 
when the Agency proposes the LTESWTR and GWR.
3. Summary of Comments
    Commenters were in general agreement that the compliance deadline 
strategy contained in the fourth option of the 1997 NODA did the best 
job of complying with the requirements to 1996 SDWA Amendments and 
meeting the objectives of the 1993 Reg. Neg. Agreement that Congress 
affirmed as part of the 1996 Amendments. Nonetheless, a number of 
commenters expressed concern about the ability of large surface water 
systems that had to make capital improvements to comply with all 
requirements of the Stage 1 DBPR and IESWTR. They pointed out that 
capital improvements include more than just the construction, but also 
financing, design, and approval.
    EPA believes that the provisions of Section 1412(b)(10) of the SDWA 
as amended allow systems the flexibility needed to comply. As noted 
earlier in this section, States may grant up to an additional two years 
compliance time for an individual system if capital improvements are 
necessary. Moreover, as both of these rules have been under negotiation 
since 1992, proposed in 1994 and further clarified in 1997, EPA 
believes that most systems have had substantial time to consider how to 
proceed with implementation and to initiate preliminary planning. 
Several commenters also supported delaying the promulgation of the 
Stage 1 DBPR for ground water systems until the GWR is promulgated, in 
order to ensure simultaneous compliance with both rules. EPA believes 
that this option would not be consistent with the reg-neg agreement, as 
endorsed by Congress, because the agreement specifies that the Stage 1 
DBPR will apply to all community and nontransient noncommunity water 
systems. Moreover, EPA has committed to the LT1 and GWR promulgation 
schedule outlined above precisely to address this issue.
    In conclusion EPA believes that the compliance deadlines outlined 
above for systems covered by this rule are appropriate and consistent 
with the requirements of the 1996 SDWA amendments. The Agency notes, 
however, that some elements of Option 4 outlined in the 1997 NODA apply 
to systems that may be covered by future Long Term Enhanced and Ground 
Water rules. EPA intends to follow the deadline strategy outlined in 
Option 4 for these future rules. However, as today's action only 
relates to the Stage 1 DBPR, the Agency will defer final action on 
deadlines associated with future rules until those rules, themselves, 
are finalized.

[[Page 69429]]

J. Public Notice Requirements

1. Today's Rule
    Today's action addresses public notification by promulgating public 
notification language for the regulated compounds in 40 CFR Section 
141.32 (e). EPA takes this opportunity to note that the 1996 amendments 
to the SDWA require the Agency to make certain changes to the public 
notice regulations. EPA intends to propose changes to the public notice 
requirements in the Federal Register shortly after promulgation of the 
Stage 1 DBPR. Applicable changes in the public notice requirements, 
when they become effective, will supersede today's provisions. In 
general, the public notification for the Stage 1 DBPR is not 
substantially changed from that included in the 1994 Proposed Stage 1 
DBPR (EPA, 1994a).
2. Background and Analysis
    Under Section 1414(c)(1) of the Act, each owner or operator of a 
public water system must give notice to the persons served by the 
system of (1) any violation of any MCL, treatment technique 
requirement, or testing provision prescribed by an NPDWR; (2) failure 
to comply with any monitoring requirement under section 1445(a) of the 
Act; (3) existence of a variance or exemption; (4) failure to comply 
with the requirements of a schedule prescribed pursuant to a variance 
or exemption; and (5) notice of the concentration level of any 
unregulated contaminant for which the Administrator has required public 
notice.
    EPA promulgated the current regulations for public notification on 
October 28, 1987 (52 FR 41534--EPA, 1987). These regulations specify 
general notification requirements, including frequency, manner, and 
content of notices, and require the inclusion of EPA-specified health 
effects information in each public notice. The public notification 
requirements divide violations into two categories (Tier 1 and Tier 2) 
based on the seriousness of the violations, with each tier having 
different public notification requirements. Tier 1 violations include 
violations of an MCL, treatment technique, or a variance or exemption 
schedule. Tier 1 violations contain health effects language specified 
by EPA which concisely and in non-technical terms conveys to the public 
the adverse health effects that may occur as a result of the violation. 
States and water utilities remain free to add additional information to 
each notice, as deemed appropriate for specific situations. Tier 2 
violations include monitoring violations, failure to comply with an 
analytical requirement specified by an NPDWR, and operating under a 
variance or exemption.
    Today's final rule contains specific health effects language for 
the contaminants which are in today's rulemaking. EPA believes that the 
mandatory health effects language is the most appropriate way to inform 
the affected public of the potential health implications of violating a 
particular EPA standard.
3. Summary of Comments
    EPA received comments on the topic of the public notification 
language for TTHM, HAA5, chlorine, chloramines, chlorine dioxide, and 
enhanced coagulation. Some commenters noted that the language in 
141.32(e)(79) is satisfactory. One commenter requested that the 
language for DBPs be modified to recognize that disinfectants react 
with naturally occurring organic and inorganic matter to form DBPs. 
Some commenters did not support the use of the same public notification 
language for both DBP MCL and enhanced coagulation treatment technique 
violations. Several commenters suggested that the content of the 
notices for chlorine, chloramine, and chlorine dioxide should reflect 
that disinfection is an essential step in surface water treatment. One 
commenter suggested that the language for chlorine dioxide acute 
effects should be deleted. Other commenters felt that the notice to 
consumers of chlorine dioxide violations at the treatment facility 
which do not result in violations in the distribution system (nonacute 
violations) should not require public notification.
    In response, EPA has modified the public notification language for 
DBPs to indicate that disinfectants react with naturally occurring 
organic and inorganic matter to form DBPs. EPA believes it is 
appropriate to use the same public notification language for the 
enhanced coagulation treatment technique violation as for violations 
for the TTHM and HAA5 MCLs, since enhanced coagulation is meant to 
limit exposure to DBPs. EPA believes the current language in the public 
notification language is appropriate to reflect that disinfection is an 
essential step in water treatment. EPA believes that since the 
potential health effects from chlorine dioxide are short-term that it 
is appropriate to maintain the acute effects language to protect the 
fetus, infants, and children. In general, the public notification 
requirements for the Stage 1 DBPR will not substantially change from 
that included in the 1994 Proposed Stage 1 DBPR (EPA, 1994a).

K. System Reporting and Record Keeping Requirements

1. Today's Rule
    The Stage 1 DBPR, consistent with the current system reporting 
regulations under 40 CFR 141.31, requires PWSs 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 10 days 
of the end of the monitoring period for less frequent monitoring. 
Systems that are required to do extra monitoring because of the 
disinfectant used have additional reporting requirements specified. 
This applies to systems that use chlorine dioxide (must report chlorine 
dioxide and chlorite results) and ozone (must report bromate results).
    Subpart H systems that use conventional treatment are required to 
report either compliance/noncompliance with DBP precursor (TOC) removal 
requirements or report which of the enhanced coagulation/enhanced 
softening exemptions they are meeting. There are additional 
requirements for systems that cannot meet the required TOC removals and 
must apply for an alternate enhanced coagulant level. These 
requirements are included in Sec. 141.134(b).
    Calculation of compliance with the TOC removal requirements is 
based on normalizing the percent removals over the most recent four 
quarters, since compliance is based on that period. Normalization, 
which would prescribe equal weight to the data collected each month, is 
necessary since source water quality changes may change the percent TOC 
removal requirements from one month to another. EPA has developed a 
sample reporting and compliance calculation sheet that will be 
available in the enhanced coagulation guidance manual to assist 
utilities in making these calculations.
2. Summary of Comments
    There were no significant comments on the system reporting and 
recordkeeping requirements and therefore EPA is finalizing the 
requirements as proposed.

L. State Recordkeeping, Primacy, and Reporting Requirements

    The SDWA provides that States and eligible Indian Tribes may assume 
primary enforcement responsibilities.

[[Page 69430]]

Fifty-four out of fifty-six State and territorial jurisdictions have 
applied for and received primary enforcement responsibility (primacy) 
under the Act. No Tribes have received primacy. To obtain primacy for 
the federal drinking water regulations, States must adopt their own 
regulations which are at least as stringent as the federal regulations. 
This section describes the regulations and other procedures and 
policies that States must adopt to implement the final Stage 1 DBPR.
    To implement the final rule, States are required to adopt the 
following regulatory requirements:

--Section 141.32, Public Notification;
--Section 141.64, MCLs for Disinfection Byproducts;
--Section 141.65, MRDLs for Disinfectants;
--Subpart L, Disinfectant Residuals, Disinfectant Byproducts, and 
Disinfection Byproduct Precursors.

    In addition to adopting regulations no less stringent than the 
federal regulations, States must adopt certain requirements related to 
this regulation in order to have their program revision applications 
approved by EPA. This rule also requires States to keep specific 
records and submit specific reports to EPA.
    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; EPA, 1998i). 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 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 national primary drinking water regulation 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 its complete and final primacy 
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.
1. State Recordkeeping Requirements
    a. Today's Rule. 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 
Stage 1 DBPR requires States to keep additional records of the 
following, including all supporting information and an explanation of 
the technical basis for each decision:
    (1) Records of determinations made by the State when the State has 
allowed systems additional time to install GAC or membrane filtration. 
These records must include the date by which the system is required to 
have completed installation;
    (2) Records of systems that are required to meet alternative 
minimum TOC removal requirements or for whom the State has determined 
that the source water is not amendable to enhanced coagulation. These 
records must include the results of testing to determine alternative 
limits and the rationale for establishing the alternative limits;
    (3) Records of subpart H systems using conventional treatment 
meeting any of the enhanced coagulation or enhanced softening exemption 
criteria;
    (4) Register of qualified operators;
    (5) Records of systems with multiple wells considered to be one 
treatment plant for purposes of determining monitoring frequency;
    (6) Records of the sampling plans for subpart H systems serving 
more than 3,300 persons must be keep on file at the State after 
submission by the system;
    (7) A list of laboratories that have completed performance sample 
analyses and achieved the quantitative results for TOC, TTHMs, HAA5, 
bromate, and chlorite; and
    (8) A list of all systems required to monitor for disinfectants and 
DBPs under subpart L.
    b. Background and Analysis. In addition to requesting comments on 
the requirements (1) through (5), and (7) and (8) listed above, EPA 
also requested comments on whether States should be required to keep 
the monitoring plan submitted by systems serving more than 3,300 people 
on file at the State after submission to make it available for public 
review.
    c. Summary of Comments. There were several commenters who suggested 
that EPA should keep in mind State budget constraints when requiring 
specific additional recordkeeping requirements. Other commenters stated 
that they believed the requirements were necessary. EPA understands 
commenters concerns with requiring recordkeeping requirements that are 
unnecessary, but believes this information is important to conduct 
effective State program oversight, including the review of State 
decisions and their basis. After further review, EPA has decided to 
eliminate the requirement in the proposal that States must keep records 
of systems that apply for alternative TOC performance criteria. EPA is 
more concerned with the systems that are required to meet alternative 
TOC performance criteria, not the systems that have applied for the 
alternative performance criteria. In addition, EPA has added three 
recordkeeping requirements, two of which were originally in the 
reporting requirements section and one for which EPA requested comment.
    The first additional requirement will require States to keep lists 
of all systems required to monitor for various disinfectants and DBPs 
(#8 above). The second additional requirement will require States to 
maintain a list of laboratories that have completed performance sample 
analyses and achieved the quantitative results for TOC, TTHMs, HAA5, 
bromate, and chlorite (#6 above). EPA believes both of these 
recordkeeping requirements are necessary to ensure adequate EPA program 
oversight. As discussed below, these two requirements are no longer in 
the State reporting requirements as EPA has decided that the 
requirements in the proposal on State reporting requirements are not 
needed on a regular basis, but are needed for program oversight. The 
third additional requirement pertains to the request for comment in the 
proposal on maintaining the monitoring plans submitted by systems (#6 
above). Several commenters supported this additional requirement 
stating that it was a necessary element for implementing the final 
rule. Others believed it was not necessary to keep this on file because 
the public could request this information from the system or the State 
as normal public records. EPA believes that it is important for States 
to review, and keep on file the systems monitoring plan to ensure that 
the PWS is monitoring and calculating compliance in accordance with the 
plan. This will also enable the public to view the plan. Thus, EPA is 
adding this requirement to the final recordkeeping requirements. In 
conclusion, based on a review of all public comments the final

[[Page 69431]]

rule contains eight State recordkeeping requirements in addition to 
those required under current regulations in Sec. 142.14.
2. Special Primacy Requirements
    a. Today's Rule. To ensure that a State program includes all the 
elements necessary for an effective and enforceable program under 
today's rule, a State application for program revision approval must 
include a description of how the State will:
    (1) Determine the interim treatment requirements for systems 
granted additional time to install GAC and membrane filtration under 
141.64(b)(2).
    (2) Qualify operators of community and nontransient noncommunity 
water systems subject to this regulation under 141.130(c). 
Qualification requirements established for operators of systems subject 
to 40 CFR Part 141 Subpart H (Filtration and Disinfection) may be used 
in whole or in part to establish operator qualification requirements 
for meeting subpart L requirements if the State determines that the 
subpart H requirements are appropriate and applicable for meeting 
subpart L requirements.
    (3) Approve DPD colorimetric tests kits for free and total chlorine 
measurements under 141.131(c)(2). State approval granted under subpart 
H (Sec. 141.74(a)(2)) for the use of DPD colorimetric test kits for 
free chlorine testing would be considered acceptable approval for the 
use of DPD test kits in measuring free chlorine residuals as required 
in subpart L.
    (4) Approve parties to conduct analyses of water quality parameters 
under 141.132(a)(2) (pH, alkalinity, bromide, and residual disinfectant 
concentration measurements). The State's process for approving parties 
performing water quality measurements for systems subject to subpart H 
requirements may be used for approving parties measuring water quality 
parameters for systems subject to subpart L requirements, if the State 
determines the process is appropriate and applicable.
    (5) Define criteria to use in determining if multiple wells are 
being drawn from a single aquifer and therefore can be considered as a 
single source under 141.132(a)(2). Such criteria will be used in 
determining the monitoring frequency for systems using only ground 
water not under the direct influence of surface water.
    (6) Approve alternative TOC removal levels as allowed under 
141.135(b).
    b. Background and Analysis. As discussed above, EPA included 
several special primacy requirements to ensure that State programs 
contain all the essential elements for an effective program. 
Specifically, EPA believes the special requirements are important to 
ensure that the process or approach used by the State for evaluating 
whether the interim treatment in place for systems granted additional 
time to install GAC or membranes or alternative enhanced coagulation 
levels will be protective of public health. The requirement to have 
qualified operators is important because the treatment technologies 
used to comply with the Stage 1 DBPR and the IESWTR simultaneously are 
complex and will require a certain level of expertise. The requirement 
to approve parties for conducting analyses of specific water quality 
parameters is important because each of the parameters required to be 
tested is critical to a specific component of the final rule (e.g., 
bromide ion is important because for bromate it is possible to reduce 
monitoring from monthly to once per quarter, if a system demonstrates 
that the average raw water bromide concentration is less than 0.05 mg/L 
based upon representative monthly measurements for one year). Finally, 
it is important to define the criteria used to determine if multiple 
wells are to be considered a single source as this could have 
significant implications for monitoring.
    c. Summary of Comments. There were no significant comments on the 
primacy requirements. The only change from the proposal was to delete 
the requirement that States must have approved parties to perform 
temperature evaluations. This requirement was included in the proposed 
rule because of the need to have accurate measurements as a part of the 
process for not allowing predisinfection credit. Since the final rule 
allows credit for compliance with applicable disinfection requirements 
consistent with the SWTR, the temperature requirement was removed.
3. State Reporting Requirements
    a. Today's Rule. EPA currently requires in Sec. 142.15 that States 
report to EPA information such as violations, variance and exemption 
status, and enforcement actions. The Stage 1 DBPR does not add any 
additional reporting requirements.
    b. Background and Analysis. The preamble to the proposed rule 
included six State reporting requirements. These included:
    (1) A list of all systems required to monitor for various 
disinfectants and disinfection byproducts;
    (2) A list of all systems for which the State has granted 
additional time for installing GAC or membrane technology and the basis 
for the additional time;
    (3) A list of laboratories that have completed performance sample 
analyses and achieved the quantitative results for TOC, TTHMs, HAA5, 
bromate, and chlorite;
    (4) A list of all systems using multiple ground water wells which 
draw from the same aquifer and are considered a single source for 
monitoring purposes;
    (5) A list of all Subpart H systems using conventional treatment 
which are not required to operate with enhanced coagulation, and the 
reason why enhanced coagulation is not required for each system; and
    (6) A list of all systems with State-approved alternate performance 
standards (alternate enhanced coagulation levels).
    c. Summary of Comments. Several commenters stated that the 
reporting requirements were not necessary to operate an oversight 
program and that these reports could be made available for EPA review 
during annual audits. EPA agrees with commenters that the reports are 
not necessary to operate an oversight program, and that if needed EPA 
could request this information from the States. However, EPA does 
believe it is important that States maintain this information in their 
records. In conclusion, based on commenters concerns and for the 
reasons cited above, the final rule contains no additional State 
reporting requirements other than those required by 142.15.

M. Variances and Exemptions

1. Today's Rule
    Variances may be granted in accordance with section 1415(a)(1)(A) 
of the SDWA and in accordance with 1415(e) and EPA's regulations. 
Exemptions may be granted in accordance with section 1416(a) of the 
SDWA and EPA's regulations.
2. Background and Analysis
    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 which has primary enforcement responsibility 
(primacy), or EPA as the primacy agency, may grant variances from MCLs 
to those public water systems of any size that cannot comply with the 
MCLs because of characteristics of the water sources. The primacy 
agency may grant general variances to a system on condition that the 
system install the best available technology, treatment techniques, or 
other means, and provided that alternative sources of water are not

[[Page 69432]]

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 (URTH) to the public served by the public water system.
    Under section 1413(a)(4), States that choose to issue general 
variances must do so under conditions, and in a manner, that are no 
less stringent than section 1415. Of course, a State may adopt 
standards that are more stringent than the EPA standards. EPA specifies 
BATs for general variance purposes. EPA may identify as BAT different 
treatments under section 1415 for variances other than the BAT under 
section 1412 for MCLs. EPA's section 1415 BAT findings may vary 
depending on a number of factors, including the number of persons 
served by the public water system, physical conditions related to 
engineering feasibility, and the costs of compliance with MCLs. In this 
final rule, EPA is not specifying different BAT for variances under 
section 1415(a). Section 1415(e) authorizes the primacy Agency (EPA or 
the State) to issue variances to small public water systems (those 
serving less than 10,000 persons) where the system cannot afford to 
comply with an MCL and where the primacy agency determines that the 
terms of the variances ensure adequate protection of public health (63 
FR 1943-57; EPA, 1998j). These variances also may only be granted where 
EPA has identified a variance technology under Section 1412(b)(15) for 
the contaminant, system size and source water quality in question.
    Prior to the 1996 SDWA amendments, EPA was required to set the MCL 
for a contaminant as close to the MCLG as is feasible. Section 
1412(b)(4)(D) of the SDWA states that ``the term ``feasible'' means 
with the use of the best technology, treatment techniques and other 
means which the Administrator finds, after examination for efficacy 
under field conditions and not solely under laboratory conditions, are 
available (taking cost into consideration).''
    The cost assessment for the feasibility determinations have 
historically been based upon impacts to regional and large metropolitan 
water systems serving populations greater than 50,000 people. Since 
large systems served as the basis for the feasibility determinations, 
the technical and/or cost considerations associated with these 
technologies often were not applicable to small water systems. While 
EPA will continue to use feasibility for large systems in setting 
NPDWRs, the 1996 amendments to the SDWA specifically require EPA to 
make small system technology assessments for both existing and future 
regulations.
    The 1996 amendments to the SDWA identifies three categories of 
small public water systems that need to be addressed: (1) those serving 
a population between 3301 to 10,000; (2) those serving a population of 
501--3300; and (3) those serving a population of 26--500. The SDWA 
requires EPA to make determinations of available compliance 
technologies and, 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 included above. 
Based on this analysis, multiple affordable compliance technologies 
were found for each of the three system sizes (EPA, 1998q and EPA, 
1998r) 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'' 
(EPA, 1998s) and the ``Variance Technology Findings for Contaminants 
Regulated Before 1996'' (EPA, 1998t).
    Exemptions. Under section 1416(a), EPA or a State may exempt a 
public water system from any requirements related to an MCL or 
treatment technique of an NPDWR, if it finds that (1) due to compelling 
factors (which may include economic factors such as qualification of 
the PWS as serving a disadvantaged community), the PWS is unable to 
comply with the requirement or implement measure to develop an 
alternative source of water supply; (2) the exemption will not result 
in an unreasonable risk to health; and; (3) the PWS was in operation on 
the effective date of the NPWDR, or for a system that was not in 
operation by that date, only if no reasonable alternative source of 
drinking water is available to the new system; and (4) management or 
restructuring changes (or both) cannot reasonably result in compliance 
with the Act or improve the quality of drinking water.
    If EPA or the State grants an exemption to a public water system, 
it must at the same time prescribe a schedule for compliance (including 
increments of progress or measures to develop an alternative source of 
water supply) and implementation of appropriate control measures that 
the State requires the system to meet while the exemption is in effect. 
Under section 1416(b)(2)(A), the schedule prescribed shall require 
compliance as expeditiously as practicable (to be determined by the 
State), but no later than 3 years after the effective date for the 
regulations established pursuant to section 1412(b)(10). For public 
water systems which do not serve more than a population of 3,300 and 
which need financial assistance for the necessary improvements, EPA or 
the State may renew an exemption for one or more additional two-year 
periods, but not to exceed a total of 6 years, if the system 
establishes that it is taking all practicable steps to meet the 
requirements above.
    A public water system shall not be granted an exemption unless it 
can establish that either: (1) the system cannot meet the standard 
without capital improvements that cannot be completed prior to the date 
established pursuant to section 1412(b)(10); (2) in the case of a 
system that needs financial assistance for the necessary 
implementation, the system has entered into an agreement to obtain 
financial assistance pursuant to section 1452 or any other Federal or 
state program; or (3) the system has entered into an enforceable 
agreement to become part of a regional public water system.
3. Summary of Comments on Variance and Exemptions
    In the 1994 proposal, EPA requested comment on whether exemptions 
to the rule should be granted if a system could demonstrate to the 
State that due to unique water quality characteristics it could not 
avoid, through the use of BAT, the possibility of increasing total 
health risk to its consumers by complying with the Stage 1 regulations. 
The Agency requested information under which such a scenario may 
unfold. Several commenters supported granting exemptions provided a 
system could demonstrate that installation of BAT will increase the 
total health risk.
    After additional consideration, EPA believes it is not appropriate, 
for several reasons, to grant exemptions based on a demonstration that 
the use of BAT could increase the total health risk by complying with 
the Stage 1 DBPR. First,

[[Page 69433]]

EPA does not believe the analytical tools and methodologies are 
currently available that would allow a determination of whether the 
total health risk from the installation of BAT would increase. Second, 
at the time of proposal there was concern that in waters with high 
bromide concentrations it may be possible to increase the 
concentrations of certain brominated DBPs when using precursor removal 
processes even though the concentrations of the TTHMs and HAA5 may 
decrease. Also, at the time of proposal, the health risks associated 
with many of the brominated DBPs was unknown, and it was unclear 
whether the benefits of lowering the concentrations of chlorinated DBPs 
outweigh the possible downside risks of increasing certain brominated 
DBPs. Since the proposal, some additional health effects research has 
been completed evaluating the toxicity of brominated DBPs. However, 
this research is still preliminary and no conclusions can be drawn on 
the potential for increased risks from the brominated DBPs. In 
addition, it is unclear to what extent the use of precursor removal 
processes will change the concentrations of certain brominated DBPs. 
The ICR data should provide some additional information that may be 
helpful in this area along with additional ongoing research. This 
information will be available for consideration in the Stage 2 rule 
deliberations. Based on the reasons stated above, EPA does not believe 
it is appropriate to allow exemptions to the rule based on a finding 
that the installation of BAT would increase the total risk from DBPs.

N. Laboratory Certification and Approval

1. Today's Rule
    EPA recognizes that the effectiveness of today's regulations 
depends on the ability of laboratories to reliably analyze the 
regulated disinfectants and DBPs at the MRDL or MCL, respectively. 
Laboratories must also be able to measure the trihalomethanes and 
haloacetic acids at the reduced monitoring trigger levels, which are 
between 25 and 50 percent of the MCLs for these compound classes. EPA 
has established State primacy requirements for a drinking water 
laboratory certification program for the analysis of DBPs. States must 
adopt a laboratory certification program as part of primacy. [40 CFR 
142.10(b)]. EPA has also specified laboratory requirements for analyses 
of DBP precursors and disinfectant residuals which must be conducted by 
approved parties. [40 CFR 141.89 and 141.74]. EPA's ``Manual for the 
Certification of Laboratories Analyzing Drinking Water'', EPA 815-B-97-
001--(EPA, 1997g), specifies the criteria for implementation of the 
drinking water laboratory certification program.
    In today's rule, EPA is promulgating MCLs for TTHMs, HAA5, bromate, 
and chlorite. Today's rule requires that only certified laboratories be 
allowed to analyze samples for compliance with the proposed MCLs. For 
the disinfectants and certain other parameters in today's rule, which 
have MRDLs or monitoring requirements, EPA is requiring that analyses 
be conducted by a party acceptable to the State.
    Performance evaluation (PE) samples, which are an important tool in 
the SDWA laboratory certification program (laboratories seeking 
certification) may be obtained from a PE provider approved by the 
National Institute of Science and Technology (NIST). To receive and 
maintain certification, a laboratory must use a promulgated method and, 
at least once per year, successfully analyze an appropriate PE sample. 
In the drinking water PE studies, NIST-approved providers will provide 
samples for bromate, chlorite, five haloacetic acids, four 
trihalomethanes, free chlorine, and alkalinity. The NIST-approved PE 
providers will provide total chlorine and TOC samples in the wastewater 
PE studies and have the potential to provide these samples for drinking 
water studies. Due to the lability of chlorine dioxide, EPA does not 
expect a suitable PE sample can be designed for chlorine dioxide 
measurements.
    PE Sample Acceptance Limits for Laboratory Certification. 
Historically, EPA has set minimum PE acceptance limits based on one of 
two criteria: statistically derived estimates or fixed acceptance 
limits. Statistical estimates are based on laboratory performance in 
the PE study. Fixed acceptance limits are ranges around the true 
concentration of the analyte in the PE sample. Today's rule combines 
the advantages of these approaches by specifying statistically-derived 
acceptance limits around the study mean, within specified minimum and 
maximum fixed criteria.
    EPA believes that specifying statistically-derived PE acceptance 
limits with upper and lower bounds on acceptable performance provides 
the flexibility necessary to reflect improvement in laboratory 
performance and analytical technologies. The acceptance criteria 
maintain minimum data quality standards (the upper bound) without 
artificially imposing unnecessarily strict criteria (the lower bound). 
Therefore, EPA is establishing the following acceptance limits for 
measurement of bromate, chlorite, each haloacetic acid, and each 
trihalomethane in a PE sample.
    EPA is defining acceptable performance for each chemical measured 
in a PE sample from estimates derived at a 95% confidence interval from 
the data generated by a statistically significant number of 
laboratories participating in the PE study. However, EPA requires that 
these acceptance criteria not exceed 50% nor be less than 
15% of the study mean. If insufficient PE study data are 
available to derive the estimates required for any of these compounds, 
the acceptance limit for that compound will be set at 50% 
of the study true value. The true value is the concentration of the 
chemical that EPA has determined was in the PE sample.
    EPA recognizes that when using multianalyte methods, the data 
generated by laboratories that are performing well will occasionally 
exceed the acceptance limits. Therefore, to be certified to perform 
compliance monitoring using a multianalyte method, laboratories are 
required to generate acceptable data for at least 80% of the regulated 
chemicals in the PE sample that are analyzed with the method. If fewer 
than five compounds are included in the PE sample, data for each of the 
analytes in that sample must meet the minimum acceptance criteria in 
order for the laboratory to be certified.
    Approval Criteria for Disinfectants and Other Parameters. Today's 
rule establishes MRDLs for the three disinfectants--chlorine, 
chloramines, and chlorine dioxide. In addition, EPA has established 
monitoring requirements for TOC, alkalinity, and bromide; there are no 
MCLs for these parameters. In previous rules [40 CFR 141.28, .74, and 
.89], EPA has required that measurements of alkalinity, disinfectant 
residuals, pH, temperature, and turbidity be made with an approved 
method and conducted by a party approved (not certified) by the State. 
In today's rule, EPA requires that samples collected for compliance 
with today's requirements for alkalinity, bromide, residual 
disinfectant, and TOC be conducted with approved methods and by a party 
approved by the State.
    Other Laboratory Performance Criteria. For all contaminants and 
parameters required to be monitored in today's rule, the States may 
impose other requirements for a laboratory to be

[[Page 69434]]

certified or a party to be approved to conduct compliance analyses.
2. Background and Analysis
    The laboratory certification and approval requirements that today's 
rule establishes are unchanged from those proposed by EPA in 1994.
3. Summary of Comments
    EPA received few comments on laboratory certification and approval. 
Commenters requested clarification of the use of the 50% 
upper bound and 15% lower bound, along with the use of 
statistically derived limits. EPA believes that statistically derived 
limits provide flexibility to allow laboratory certification standards 
to reflect improvement in laboratory performance and analytical 
technologies. As laboratories become more proficient in conducting 
these analyses, statistically derived acceptance limits may drop. 
However, to prevent the exclusion of laboratories capable of producing 
data of sufficient quality for compliance purposes, EPA has established 
a lower bound for acceptance limits of 15%. EPA is imposing 
an upper bound on acceptable performance to establish minimum data 
quality standards. Results outside of this range have unacceptable 
accuracy for compliance determinations. These upper and lower bounds 
were not determined statistically; they are the data quality objectives 
the Agency has determined as acceptable.

IV. Economic Analysis

    Under Executive Order 12866, Regulatory Planning and Review, EPA 
must estimate the costs and benefits of the Stage 1 DBPR in a 
Regulatory Impact Analysis (RIA) and submit the analysis to Office of 
Management and Budget (OMB) in conjunction with publishing the final 
rule. EPA has prepared an RIA to comply with the requirements of this 
Order. This section provides a summary of the information from the RIA 
for the Stage 1 DBPR (USEPA 1998g).

A. Today's Rule

    EPA has estimated that the total annualized cost, for implementing 
the Stage 1 DBPR is $701 million in 1998 dollars (assuming a 7 percent 
cost of capital). This estimate includes annualized treatment costs to 
utilities ($593 million), start-up and annualized monitoring costs to 
utilities ($91.7 million), and startup and annualized monitoring costs 
to states ($17.3 million). Annualized treatment costs to utilities 
includes annual operation and maintenance costs ($362 million) and 
annualized capital costs assuming 7 percent cost of capital ($230 
million). The basis for these estimates, and alternate cost estimates 
using different cost of capital assumptions are described later in this 
section. While the benefits of this rule are difficult to quantify 
because of the uncertainty associated with risks from exposure to DBPs 
(and the resultant reductions in risk due to the decreased exposure 
from DBPs), EPA believes that there is a reasonable likelihood that the 
benefits will exceed the costs. Various approaches for assessing the 
benefits are considered and described in the benefits and net benefits 
sections of this preamble.

B. Background

1. Overview of RIA for the Proposed Rule
    In the RIA for the 1994 proposed Stage 1 DBPR (EPA, 1994i) EPA 
estimated the national capital and annualized utility costs (sum of 
amortized capital and annual operating costs, assuming 10% cost of 
capital) for all systems at $4.4 billion and $1.04 billion, 
respectively. The cost and reduction in DBP exposure estimates of the 
1994 RIA were derived using a Disinfection Byproduct Regulatory 
Analysis Model (DBPRAM). The DBPRAM consisted of a collection of 
analytical models which used Monte Carlo simulation techniques to 
produce national forecasts of compliance and exposure reductions for 
different regulatory scenarios. The TWG, representing members of the 
Reg. Neg. Committee, used the best available information at the time as 
inputs to the DBPRAM, and for making further adjustments to the model 
predictions. The Stage 1 DBPR compliance and exposure forecasts were 
affected by constraints imposed by the 1994 proposed IESWTR option 
which would have required systems to provide enough disinfection, while 
not allowing for disinfection credit prior to TOC removal by enhanced 
coagulation, to achieve a 10-4 annual risk of infection from 
Giardia (EPA, 1994a). The compliance forecast assumed that a 
substantial number of systems would need to install advanced 
technologies to meet the Stage 1 DBPR because of needing to achieve the 
10-4 annual risk level from Giardia while no longer being 
allowed disinfection credit prior to TOC removal.
    Predicted benefits for the proposed Stage 1 DBPR were derived 
assuming a baseline risk ranging from 1 to 10,000 cancer cases per year 
(based on analysis of available toxicological and epidemiological data) 
and assuming reductions in the cancer risks were proportional to 
reductions in TTHM, HAA5, or TOC levels (predicted from compliance 
forecasts). Negotiators agreed that the range of possible risks 
attributed to chlorinated water should consider both toxicological data 
and epidemiological data, including the Morris et al. (1992) estimates. 
No consensus, however, could be reached on a single likely risk 
estimate. Therefore, the predicted benefits for the proposal ranged 
from one to several thousands cases of cancer being avoided per year 
after implementation of the Stage 1 DBPR. Despite, the uncertainty in 
quantifying the benefits from the Stage 1 DBPR, the Reg. Neg. Committee 
recognized that risks from chlorinated water could be large, and 
therefore should be reduced. The Reg. Neg. Committee also recommended 
that the proposed Stage 1 DBPR provided the best means for reducing 
risks from DBPs until better information become available.
    For a more detailed discussion of the cost and benefit analysis of 
the 1994 proposed DBPR refer to the preamble of the proposed rule (EPA, 
1994a) and the RIA for the proposed rule (EPA, 1994i).
2. Factors Affecting Changes to the 1994 RIA
    a. Changes in Rule Criteria. Based on the new data reflecting the 
feasibility of enhanced coagulation, as discussed previously, the 
enhanced coagulation requirements were modified by decreasing the 
percent TOC removal requirements by 5 percent for systems with low TOC 
level waters (i.e., 2-4 mg/L TOC). These new percent TOC removal 
requirements were used with new source and finished water TOC 
occurrence data to revise the estimates for the number of systems 
requiring enhanced coagulation.
    The IESWTR was revised from the proposal to allow inactivation 
credit for disinfection prior to and during stages of treatment for 
precursor removal. Also, the proposed IESWTR was revised to include 
disinfection benchmark criteria, in lieu of requiring treatment to an 
acceptable risk level, to prevent increases in microbial risk while 
systems complied with the Stage 1 DBPR. These two rule changes were 
considered in revising the forecasts of compliance and changes in 
exposure resulting from the Stage 1 DBPR.
    b. New Information Affecting DBP Occurrence and Compliance 
Forecasts. Since the rule was proposed, new sources of data have become 
available that were used to update the 1994 RIA. The new data includes:

[[Page 69435]]

     Updated costs for different treatment technologies (e.g., 
membranes) used in the DBP Cost and Technology Document, (EPA, 1998k);
     1996 data from the AWWA Water Industry Data Base on TOC, 
TTHM and HAA5 occurrence, and disinfection practices;
     Plant schematics of treatment processes for ICR utilities;
     Research data from numerous sources regarding the efficacy 
of enhanced coagulation for precursor removal and resultant DBP 
formation (Krasner, 1997; and EPA, 1997b);
     New research results produced in jar tests by TWG members 
documenting the effect of moving the point of predisinfection under 
varying conditions (Krasner, 1997 and EPA, 1997b).
    This new information has been described in the 1997 DBP NODA (EPA, 
1997b). Public comments received in 1997, supported using the above 
information in revising the decision tree analysis. Discussion on the 
decision tree changes are in section IV.C of this preamble.
    c. New Epidemiology Information. Since the proposal, EPA has 
completed an reassessment of the Morris et al. (1992) meta-analysis 
(Poole, 1997). Review of the meta-analysis indicated that the estimate 
of cancer cases had limited utility for risk assessment purposes for 
methodological reasons (EPA, 1998l and EPA, 1998m). EPA has decided not 
to use the Morris et al. (1992) meta-analysis to estimate the potential 
benefits from the Stage 1 DBPR. EPA has considered new epidemiology 
studies conducted since the time of proposal and completed an 
assessment of the potential number of bladder cancer cases that could 
be attributed to exposure from chlorinated surface waters. Based on 
this assessment of epidemiological studies, EPA estimates that between 
1100-9300 bladder cancer cases per year could be attributed to exposure 
to chlorinated surface waters (EPA, 1998c). Due to the wide uncertainty 
in these estimates, the true number of attributable cases could also be 
zero. The basis for these bladder cancer case estimates and potential 
reductions in risk resulting from the Stage 1 DBPR is discussed further 
in the benefits and net benefits sections that follow.

C. Cost Analysis

    National cost estimates of compliance with the Stage 1 DBPR were 
derived from estimates of utility treatment costs, monitoring and 
reporting costs, and start-up costs. Utility treatment costs were 
derived using compliance forecasts of technologies to be used and unit 
costs for the different technologies.
1. Revised Compliance Forecast
    The TWG, supporting the M-DBP Advisory Committee, used the 1996 
AWWA Water Industry Data Base (WIDB) to reevaluate the compliance 
decision tree used in the RIA for the 1994 proposal. The WIDB provided 
occurrence data on TOC level in raw water and finished water, TTHM and 
HAA5 levels within distribution systems, and information on 
predisinfection practices.
    The above information was used to predict treatment compliance 
choices that plants would likely make under the Stage 1 DBPR. Table IV-
1 illustrates how the compliance forecast changed for large systems 
using surface water since the time of proposal.

 Table IV-1.--Comparisons of Compliance Forecasts for Surface Water Systems Serving 10,000 Population
                                      From the 1994 Proposal and Final Rule
----------------------------------------------------------------------------------------------------------------
                                                                       1994                       1998
                         Treatment                         -----------------------------------------------------
                                                             # systems     % systems    # systems     % systems
----------------------------------------------------------------------------------------------------------------
(A) No Further Treatment..................................          386          27.7          544          39.0
(B) Chlorine/Chloramines..................................           41           2.9          231          16.6
(C) Enhanced Coagulation + Chloramines....................          136           9.7          265          19.0
(D) Enhanced Coagulation + Chlorine.......................          600          43.0          265          19.0
(E) Ozone, Chlorine Dioxide, Granular Activated Carbon,
 Membranes................................................          232          16.6           90           6.5
                                                           -----------------------------------------------------
    Total *...............................................        1,395         100          1,395         100
----------------------------------------------------------------------------------------------------------------
* May not add to total due to independent rounding.

Notable is that the percentage of systems predicted to use advanced 
technologies (ozone, chlorine dioxide, GAC, or membrane) dropped from 
17 percent to 6.5 percent since proposal, and the percentage of systems 
not affected by the rule increased from 28 percent to 39 percent. This 
shift in predicted compliance choices is mainly attributed to less 
stringent disinfection requirements under the IESWTR which would reduce 
the formation of DBPs and reduce the number of systems requiring 
treatment to meet the Stage 1 DBPR. It also appears that a substantial 
number of systems may have already made treatment changes to comply 
with the 1994 proposed rule.
    Table IV-2 illustrates how the compliance forecast changed for 
small systems using surface water since the time of proposal. As for 
large systems, the percentage of systems predicted to use advanced 
technologies dropped substantially, from 17 percent to 6.5 percent. 
This drop in use of advanced technology (i.e., ozone/chloramines and 
membrane technologies) is attributed to the change in the IESWTR (as 
described above) from the time of proposal. However, unlike for large 
systems, the overall percentage of systems predicted to require 
treatment modifications did not change. A higher percentage of small 
systems (70 percent) are predicted to be affected than large systems 
(61 percent) because previously smaller systems did not have to comply 
with a TTHM standard.

[[Page 69436]]



  Table IV-2.--Comparison of Compliance Decision Tree for Surface Water Systems Serving <10,000 Population From
                                        the 1994 Proposal and Final Rule
----------------------------------------------------------------------------------------------------------------
                                                                       1994                       1998
                                                           -----------------------------------------------------
                                                             # systems     % systems    # systems     % systems
----------------------------------------------------------------------------------------------------------------
No Further Treatment......................................        1,549          30          1,549          30
Number of Affected Systems................................        3,615          70          3,615          70
Treatment:
    Chlorine/Chloramine...................................          155           3.0          826          16.0
    Enhanced Coagulation..................................        2,169          42.0        1,983          38.4
    Enhanced Coagulation/Chloramine.......................          465           9.0          465           9.0
    Ozone/Chloramine......................................          258           5.0          184           3.6
    Enhanced Coagulation+Ozone, Chloramine................          258           5.0            0           0
    Membranes.............................................          310           6.0          157           3.0
----------------------------------------------------------------------------------------------------------------

    Table IV-3 illustrates the compliance forecast for ground water 
systems. This forecast did not change from the time of proposal. A 
smaller percentage of small ground water systems are anticipated to 
need treatment changes (12 percent) than large ground water systems (15 
percent) because the use of disinfectants is more prevalent in large 
versus small ground water systems.

                       Table IV-3.--Compliance Decision Tree for All Ground Water Systems
----------------------------------------------------------------------------------------------------------------
                                                                   Systems <10,000          Systems 10,000
                                                                                       -------------------------
                                                               # systems    % systems    # systems    % systems
----------------------------------------------------------------------------------------------------------------
No Further Treatment........................................       59,847           88        1,122           85
Percentage of Affected Systems..............................        8,324           12          198           15
Treatment:
    Chlorine/Chloramine.....................................        5,403            8          119            9
    Ozone/Chloramine........................................            0            0           26            2
    Membranes...............................................        2,921            4           53            4
----------------------------------------------------------------------------------------------------------------

2. System Level Unit Costs
    Tables IV-4 and IV-5 present the unit cost estimates in 1998 
dollars that were utilized for each of the different treatment 
technologies in each system size category. Unit costs are presented in 
$ per 1000 gallons which includes operation and maintenance costs and 
amortized capital costs (using a 7% discount rate and a 20 year 
amortization period). One dollar per thousand gallons equates to 
approximately $100 per household per year as an average for communities 
in the U.S. More detailed information on these unit costs is available 
from the EPA's Cost and Technology Document (EPA, 1998k).

                                              Table IV-4.--Surface Water Systems Costs for DBP Control Technologies ($/Kgal) at 7% Cost of Capital
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                   Population size category
                                                             -----------------------------------------------------------------------------------------------------------------------------------
                                                                25-100    100-500     500-1K     1-3.3K    3.3-10K     10-25K     25-50K     50-75K    75-100K   100K-500K   500K-1M      >1M
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Chlorine/Chloramine.........................................       0.71       0.19       0.06       0.03       0.03       0.02       0.01       0.01       0.01       0.01       0.01       0.01
Enhanced Coagulation (EC)...................................       0.15       0.13       0.12       0.11       0.09       0.08       0.07       0.07       0.07       0,07       0.06       0.06
EC/Chloramine...............................................       0.87       0.32       0.18       0.14       0.12       0.09       0.08       0.08       0.08       0.07       0.07       0.07
Ozone/Chloramine............................................      12.67       3.21       1.05       0.52       0.38       0.23       0.13       0.10       0.08       0.06       0.04       0.04
EC+Ozone, Chloramine........................................      12.82       3.34       1.17       0.63       0.47       0.30       0.20       0.17       0.15       0.13       0.11       0.10
EC+GAC10....................................................       6.24       2.43       1.21       0.81       0.59       0.46       0.37       0.35       0.29       0.24       0.19       0.16
EC+GAC20....................................................      14.11       5.87       3.45       2.45       1.87       1.48       1.05       1.00       0.90       0.64       0.48       0.41
Chlorine Dioxide............................................      24.33       5.73       1.65       0.64       0.24       0.11       0.07       0.07       0.06       0.05       0.04       0.04
Membranes...................................................       3.40       3.47       3.39       2.65       1.72       0.96       0.96       0.87       0.87       0.87       0.87       0.87
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


                                               Table IV-5.--Ground Water Systems Costs for DBP Control Technologies ($/Kgal) at 7% Cost of Capital
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                   Population size category
                                                             -----------------------------------------------------------------------------------------------------------------------------------
                                                                25-100    100-500     500-1K     1-3.3K    3.3-10K     10-25K     25-50K     50-75K    75-100K   100K-500K   500K-1M      >1M
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Chlorine/Chloramine.........................................       0.72       0.19       0.06       0.03       0.03       0.02       0.01       0.01       0.01       0.01       0.01       0.01
Ozone/Chloramine............................................      12.67       3.21       1.05       0.52       0.38       0.23       0.13       0.10       0.08       0.06       0.04       0.04
Membranes...................................................       3.41       3.47       3.39       2.65       1.72       0.96       0.96       0.87       0.87       0.87       0.87       0.87
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

3. National Costs
    Table IV-6 provides a detailed summary of national costs in 1998 
dollars under the Stage 1 DBPR for different cost of capital 
assumptions under a 20 year amortization period. A cost of capital rate 
of 7 percent was used to calculate the unit costs for the national 
compliance cost model. This rate represents the standard discount rate 
preferred by OMB for benefit-cost analyses of government programs and 
regulations. The 3 percent and 10 percent rates are provided as a 
sensitivity analysis to show different assumptions about the cost of 
capital that would affect estimated

[[Page 69437]]

costs. The 10 percent rate also provides a link to the 1994 Stage 1 
DBPR cost analysis which was based on a 10 percent rate. EPA believes 
that the cost estimates presented in Table IV-6 are probably within +/
-30 percent. Uncertainty around the cost estimates pertain to 
compliance forecast estimates, unit cost estimates for the different 
technologies as they may pertain to individual sites, and estimated 
costs associated with monitoring.

                                               Table IV-6.--Summary of Costs Under the Stage 1 DBPR ($000)
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                       Surface water systems                   Ground water systems
                       Utilities Costs                        ------------------------------------------------------------------------------ All systems
                                                                  Small        Large        Total        Small        Large        Total
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Summary of Costs at 3 Percent Cost of Capital
--------------------------------------------------------------------------------------------------------------------------------------------------------
                       Treatment Costs
 
Total Capital Costs..........................................      242,652      554,564      797,216      997,537      528,539    1,526,076    2,323,292
Annual O&M...................................................       23,068      201,308      224,376       83,910       54,243      137,153      362,530
Annualized Capital Costs.....................................       16,326       37,161       53,487       67,287       35,618      102,905      156,392
Annual Utility Treatment Costs...............................       39,394      238,469      277,863      151,197       89,861      240,058      518,922
Monitoring and Reporting Cost:
    Start-Up Costs...........................................           59           28           87          674           26          700          787
    Annual Monitoring........................................       10,867       14,619       25,486       38,803       26,326       65,129       90,615
State Costs:
    Start-Up Costs...........................................  ...........  ...........  ...........  ...........  ...........  ...........        2,919
    Annual Monitoring........................................  ...........  ...........  ...........  ...........  ...........  ...........       13,243
                                                              ------------------------------------------------------------------------------------------
        Total Annual Costs at 3 Percent Cost of Capital......  ...........  ...........  ...........  ...........  ...........  ...........      626,486
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                      Summary of Costs at 7 Percent Cost of Capital
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total Capital Costs..........................................      242,652      554,564      797,216      997,537      528,539    1,526,076    2,323,292
Annual O&M...................................................       23,068      201,308      224,376       83,910       54,243      137,153      362,530
Annualized Capital Costs.....................................       22,786       62,355       85,141       94,403       50,046      144,499      229,590
Annual Utility Treatment Costs...............................       45,855      263,663      309,518      178,313      104,289      282,602      592,120
Monitoring and Reporting Cost:
    Start-Up Costs...........................................           82           39          121          946           36          982        1,103
    Annual Monitoring........................................       10,867       14,619       25,486       38,803       26,326       65,129       90,615
--------------------------------------------------------------------------------------------------------------------------------------------------------
State Costs:
    Start-Up Costs...........................................  ...........  ...........  ...........  ...........  ...........  ...........        4,099
    Annual Monitoring........................................  ...........  ...........  ...........  ...........  ...........  ...........       13,243
                                                              ------------------------------------------------------------------------------------------
        Total Annual Costs at 7 Percent Cost of Capital......  ...........  ...........  ...........  ...........  ...........  ...........      701,180
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                     Summary of Costs at 10 Percent Cost of Capital
--------------------------------------------------------------------------------------------------------------------------------------------------------
Total Capital costs..........................................      242,652      554,564      797,216      997,537      528,539    1,526,076    2,323,292
Annual O&M...................................................       23,068      201,308      224,376       83,910       54,243      137,153      362,530
Annualized Capital Costs.....................................       28,423       74,639      103,062      117,328       62,522      179,850      282,912
Annual Utility Treatment Costs...............................       51,491      275,947      327,438      201,238      116,765      317,003      645,442
Monitoring and Reporting Cost:
    Start-Up Costs...........................................          102           48          150        1,177           45        1,222        1,372
    Annual Monitoring........................................       10,867       14,619       25,486       38,803       26,326       65,129       90,615
State Costs:
    Start-Up Costs...........................................  ...........  ...........  ...........  ...........  ...........  ...........        5,100
    Annual Monitoring........................................  ...........  ...........  ...........  ...........  ...........  ...........       13,243
                                                              ------------------------------------------------------------------------------------------
        Total Annual Costs at 10 Percent Cost of Capital.....  ...........  ...........  ...........  ...........  ...........  ...........      755,772
--------------------------------------------------------------------------------------------------------------------------------------------------------

    The total national costs of the final Stage 1 DBPR are less than 
estimated in the RIA for the proposed rule in 1994. The estimated 
capital costs of the 1994 proposal in 1998 dollars is $4.97 billion and 
the total annual cost (assuming a 10 percent cost of capital as was 
assumed in 1994) is $1.3 billion. The drop in national costs from the 
1994 proposal is mainly attributed to the lowering of the number of 
surface water systems anticipated to need advanced technologies and 
lower membrane technology costs as described above.

D. Benefits Analysis

1. Exposure Assessment
    A large portion of the U.S. population is exposed to DBPs via 
drinking water. Over 200 million people in the U.S. are served by PWSs 
which apply a disinfectant (e.g., chlorine) to water in order to 
provide protection against microbial contaminants. Because of the large 
number of people potentially exposed to DBPs, there is a substantial 
concern for any health risks which may be associated with exposure to 
DBPs.
    Several factors are necessary to assess the exposure to DBPs: the 
size of the population potentially at risk; the method and rate of 
ingestion; and the concentration of DBPs in drinking

[[Page 69438]]

water. Because DBPs are formed in drinking water by the reaction of 
disinfectants with natural organic and inorganic matter, the population 
at risk is identified as the population served by drinking water 
systems that disinfect. The population served by each of four system 
categories, taken from recent Safe Drinking Water Act Information 
System data (SDWIS) is estimated in Table IV-7. Based on recent 
information from SDWIS, it was assumed that all surface water systems 
disinfect and a portion of ground water systems disinfect (95 percent 
by population among large systems and 83 percent by population among 
small systems). Approximately 239 million persons are estimated to be 
served by water systems that disinfect and are potentially exposed to 
DBPs. This widespread exposure represents over 88 percent of the total 
U.S. population (270 million). The route of exposure is through 
drinking disinfected tap water.

                               Table IV-7.--Population Potentially Exposed to DBPs
----------------------------------------------------------------------------------------------------------------
                                                                                       % of
                                                                                    population      Population
                                                                    Population       receiving       served by
                                                                      served        disinfected    systems that
                                                                                       water         disinfect
----------------------------------------------------------------------------------------------------------------
Large Surface Water: >10,000 persons............................     141,297,000             100     141,297,000
Small Surface Water: <10,000 persons............................      17,232,000             100      17,232,000
Large Ground Water: >10,000 persons.............................      56,074,000              95      53,270,300
Small Ground Water: < 10,000 persons............................      32,937,000              83      27,337,710
                                                                 -----------------------------------------------
    Total.......................................................  ..............  ..............     239,137,010
----------------------------------------------------------------------------------------------------------------

    In general, little data are available on the occurrence of DBPs on 
a national basis. Although there is sufficient occurrence data 
available for THMs in large water systems to develop a national 
occurrence distribution for that subset of systems, data are limited 
for small water systems. Similarly, some occurrence data for HAA5 are 
available for large surface water systems, but not small surface water 
and groundwater systems.
2. Baseline Risk Assessment Based on TTHM Toxicological Data
    EPA performed a quantitative risk assessment using the dose-
response information on THMs. This assessment, however, captures only a 
portion of the potential risk associated with DBPs in drinking water. 
It is not possible, given existing toxicological and exposure data, to 
gauge how much of the total cancer risk associated with the consumption 
of chlorinated drinking water is posed by TTHMs alone. An assessment of 
THMs, however, provides some estimation of the potential human risk, 
albeit limited.
    Performing the risk assessment based on TTHM toxicological data 
requires making several assumptions and extrapolations (from a nonhuman 
species to humans, from high doses in the laboratory study to lower 
environmental exposures, and from a nondrinking water route to the 
relevant route of human exposure). Assumptions are also made about the 
occurrence of TTHMs and the individual DBPs. EPA estimated the pre-
Stage 1 DBPR TTHM concentration levels by calculating a weighted 
average (based on populations receiving disinfected waters) of TTHM 
levels among the different system type categories described in Table 
IV-7. TTHM levels among systems serving greater than 10,000 people were 
estimated based on average concentrations among systems in AWWA's WIDB. 
TTHM levels in systems serving less than 10,000 people were estimated 
through modeling. Modeling consisted of applying TTHM predictive 
equations to estimates of DBP precursor levels and treatment 
conditions. The mean weighted average baseline TTHM concentrations 
among all the system type categories was 44 g/L.
    Occurrence data from an EPA DBP field study indicate that 
chloroform is the most common THM (in general, about 70 percent of 
total THMs), with bromoform being the least common (1 percent). 
Bromodichloromethane has an occurrence of approximately 20 percent of 
the total THMs, with dibromochloromethane comprising the final 8 
percent of the total THMs. In the absence of more detailed occurrence 
data, these proportions are used to divide the average TTHM 
concentration into the concentration for the four individual compounds.
    Two estimates of risk factors were used to estimate the cancer 
incidence. The first set of lifetime unit risk factors represent the 
upper 95 percent confidence limit of the dose-response function. The 
second estimate of lifetime unit risk is the maximum likelihood 
estimate used in the 1994 analysis that represents the central tendency 
of the dose-response function (Bull, 1991). The annual unit risk is 
calculated by dividing the lifetime risk by a standard assumption of 70 
years per lifetime. To calculate the annual incidence of cancer due to 
consumption of TTHMs in drinking water, the annual drinking water unit 
risk is multiplied by the number of units, in this case the 
concentration of TTHMs in g/L, broken out into individual THMs 
based on the proportions presented above. Based on these cancer risk 
estimates derived from laboratory animal studies, the annual 95th 
percentile upper bound number of cancer cases attributable to TTHMs is 
approximately 100. This means that there is a 95 percent chance that 
the annual number of cases are less than or equal to 100. Using the 
maximum likelihood or ``best'' estimates, the annual number of cancer 
cases is about 2.
3. Baseline Analysis Based on Epidemiology Data
    Epidemiological studies can be used to assess the overall 
population risk associated with a particular exposure. Since the late 
1970s, epidemiological investigations have attempted to assess whether 
chlorinated drinking water contributes to the incidence of bladder, 
colon, rectal, and other cancers. Several studies have reported a weak 
association between bladder cancer and exposure to chlorinated drinking 
water, but a causal relationship has not been confirmed (Freedman, et 
al., 1997).
    Several cancer epidemiological studies examining the association 
between exposure to chlorinated surface water and cancer were published 
subsequent to the 1994 proposed rule and the 1992 meta-analysis. In 
general, these new studies are better designed than the studies 
published prior to the 1994 proposal. The new studies include incidence 
of disease, interviews with the study subjects, and better exposure 
assessments. More evidence is available

[[Page 69439]]

on bladder cancer for a possible association to exposure to chlorinated 
surface water than other cancer sites. Because of the limited data 
available for other cancer sites such as colon and rectal cancer, the 
RIA focuses on bladder cancer.
    Based on the best studies, a range of potential risks was developed 
through the use of the population attributable risk (PAR) concept. 
Epidemiologists use PAR to quantify the fraction of disease burden in a 
population (e.g., bladder cancer) that could be eliminated if the 
exposure (e.g., chlorinated drinking water) was absent. PAR (also 
referred to as attributable risk, attributable portion, or etiologic 
fraction) provides a perspective on the potential magnitude of risks 
associated with various exposures under the assumption of causality. 
For example, the National Cancer Institute estimates that there will be 
54,500 new cases of bladder cancer in 1997. If data from an 
epidemiological study analyzing the impact of consuming chlorinated 
drinking water reports a PAR of 1 percent, it can be estimated that 545 
(54,500  x  .01) bladder cancer cases in 1997 may be attributable to 
chlorinated drinking water.
    Under the Executive Order #12866 that requires EPA to conduct a 
RIA, EPA has chosen to estimate an upper bound bladder cancer risk 
range for chlorinated drinking water using the PAR. EPA suggested this 
approach in the 1998 NODA (EPA, 1998a). While EPA recognizes the 
limitations of the current epidemiologic data base for making these 
estimates, the Agency considers the data base reasonable for use in 
developing an upper bound estimate of bladder cancer risk for use in 
the RIA. In light of the toxicological evidence, EPA recognizes that 
the risks from chlorinated drinking water may be considerably lower 
than those derived from the currently available epidemiological 
studies. EPA selected studies for inclusion in the quantitative 
analysis if they contained the pertinent data to perform a PAR 
calculation and met all three of the following criteria:
    1. The study was a population-based, case-control, or cohort study 
conducted to evaluate the relationship between exposure to chlorinated 
drinking water and incidence of cancer cases, based on personal 
interviews; (all finally selected studies were population-based, case-
control studies)
    2. The study was of high quality and well designed (e.g., adequate 
sample size, high response rate, adjusted for known confounding 
factors); and,
    3. The study had adequate exposure assessments (e.g., residential 
histories, actual THM data).
    Using the above criteria, five bladder cancer studies were selected 
for estimating the range of PARs.
     Cantor, et al., 1985;
     McGeehin, et al., 1993;
     King and Marrett, 1996;
     Freedman, et al., 1997; and
     Cantor, et al., 1998.
    The PARs from the five bladder cancer studies ranged from 2 percent 
to 17 percent. These values were derived from measured risks (Odds 
Ratio and Relative Risk) based on the number of years exposed to 
chlorinated surface water. Because of the uncertainty in these 
estimates, it is possible that the PAR could also be zero. The 
uncertainties associated with these PAR estimates are large due to the 
common prevalence of both the disease (bladder cancer) and exposure 
(chlorinated drinking water).
    In order to apply these PAR estimates to the U.S. population to 
estimate the number of bladder cancer cases attributable to DBPs in 
drinking water, a number of assumptions must be made. These include: 
(1) that the study populations selected for each of the cancer 
epidemiology studies are reflective of the entire population that 
develops bladder cancer; (2) that the percentage of those cancer cases 
in the studies exposed to chlorinated drinking water are reflective of 
the bladder cancer cases in the U.S.; (3) that DBPs were the only 
carcinogens in these chlorinated surface waters; and (4) that the 
relationship between DBPs in chlorinated drinking water exposure and 
bladder cancer is causal.
    The last of these assumptions is perhaps the most open to question. 
As noted in the March 1998 NODA, the results of the studies are 
inconsistent. In light of these concerns, the Agency agrees that 
causality between exposure to chlorinated water and bladder cancer has 
not been established and that the number of cases attributable to such 
exposures could be zero.
    Based on the estimate of 54,500 new bladder cancer cases per year 
nationally, as projected by the National Cancer Institute for 1997, the 
numbers of possible bladder cancer cases per year potentially 
associated with exposures to DBPs in chlorinated drinking water 
estimated from the five studies range from 1,100 (0.02  x  54,500) to 
9,300 (.17  x  54,500) cases. As noted above, due to the uncertainty in 
these estimates, the number of cases could also be zero. In making 
these estimates it is necessary to assume that these bladder cancer 
cases are attributed to DBPs in chlorinated surface water, even though 
the studies examined the relationship between chlorinated surface water 
and bladder cancer. This derived range is not accompanied by confidence 
intervals (C.Is), but the C.Is. are likely to be very wide. EPA 
believes that the mean risk estimates from each of the five studies 
provides a reasonable estimate of the potential range of risk suggested 
by the different epidemiological studies. Table IV-8 contains a summary 
of the risk estimates from the 1994 draft RIA and the estimates derived 
from the more recent analysis.
    A related analysis based on odds ratios was conducted to derive a 
range of plausible estimates for cancer epidemiologic studies (EPA, 
1998n). This analysis was also based on bladder cancer studies (the 
five studies cited above in addition to Doyle et al. 1997). For the 
purpose of this exercise, the annual U.S. expected number of 47,000 
bladder cancers cited by Morris et al.(1992) was used to calculate 
estimates of the cancers prevented. The number of cancers attributable 
to DBP exposure was estimated not to exceed 2,200-9,900 per year and 
could include zero. As would be expected from related analysis 
performed in the same data, this range is similar to the 1,100-9300 PAR 
range. EPA has used the 1100-9300 PAR range for the RIA.

                           Table IV-8.--Number of Cancer Cases Attributable to DBPs: Comparison of Estimates in 1994 and 1998
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                         1994 estimates                                          1998 estimates
--------------------------------------------------------------------------------------------------------------------------------------------------------
Number of New Bladder Cancer Cases/Year.  Approx. 50,000..............................  54,500.
Number of Estimated Deaths Due to         Did not state...............................  12,500.
 Bladder Cancer/Year.
 
 Attributable to DBPs in Drinking Water
 
Data Source.............................  >15 studies.................................  5 studies that meet specific criteria.
Causality...............................  No..........................................  No.
Percent Attributable to DBPs............  Did not state...............................  2% to 17%.

[[Page 69440]]

 
Number of Cancer Cases Attributable to
 DBPs:
    Estimated Using Toxicological Data..  Less than 1*................................  Zero to 100.**
    Estimated Using Epidemiological Data  Over 10,000***..............................  Zero to 9,300.****
--------------------------------------------------------------------------------------------------------------------------------------------------------
* Based on maximum likelihood estimates of risk from THMs.
** Based on IRIS 95th percent C.I. estimates of risk from THMs.
*** Indicates rectal and bladder cancer cases.
**** Indicates only bladder cancer cases.

    The current benefits analysis is structured in roughly the same 
manner as that presented in the 1994 RIA. The baseline cancer risks 
could lie anywhere from zero to 100 cases per year based on 
toxicological data; and zero to 9,300 cases per year based on 
epidemiological data. Consequently, the task is to assess the economic 
benefit of the final Stage 1 DBPR in the face of this broad range of 
possible risk.
4. Exposure Reduction Analysis
    EPA predicted exposure reductions due to the current Stage 1 DBPR 
relative to the present baseline. EPA used the concentration of TTHMs 
as a marker to measure the exposure to the range of DBPs because data 
are available on the baseline occurrence and formation of TTHMs. There 
are limited data on the total mix of byproducts in drinking water. 
Therefore, the reduction in TTHMs is assumed to reflect the reduction 
in exposure to all DBPs. To determine the change in exposure, it is 
necessary to estimate the pre-Stage 1 baseline average TTHM 
concentration and the post Stage 1 average TTHM concentration. The 
difference in the pre-and post-Stage 1 TTHM concentrations reflect the 
potential reduction in TTHMs and thus in DBPs.
    As described previously, the estimated pre-Stage 1 TTHM weighted 
average concentration is 44 g/L for all system sizes and types 
of systems. The post Stage 1 TTHM concentrations for each system 
category were estimated based on the technology compliance forecasts 
previously discussed and estimated reductions in TTHM levels depending 
upon technology. The post-Stage 1 TTHM weighted average concentration 
is estimated at 33 g/L. This represents a 24 percent reduction 
in TTHM levels resulting from the Stage 1 DBPR. Further details of the 
above analysis is described in the RIA for the Stage 1 DBPR (USEPA, 
1998g).
5. Monetization of Health Endpoints
    The range of potential benefits from the Stage 1 DBPR can be 
estimated by applying the monetary values for fatal and nonfatal 
bladder cancer cases with the estimate of the number of bladder cancer 
cases reduced by the rule. The following assumptions are used to 
estimate the range of potential benefits:
     An estimate of the number of bladder cancer cases 
attributable to DPBs in drinking water ranging from 0 to 9,300 
annually.
     A 24 percent reduction in exposure to TTHMs due to the 
Stage 1 DBPR (75 percent CI of 19 to 30 percent) will result in an 
equivalent reduction in bladder cancer cases
     A value per statistical life saved for fatal bladder 
cancers represented by a distribution with a mean of $5.6 million
     A willingness to pay to avoid a nonfatal case of bladder 
cancer represented by a distribution with a mean of $587,500
    Using the low end of the risk range of 0 bladder cancer cases 
attributable to DBPs results in a benefits estimate of $0. To calculate 
the high end of the range, the 9,300 estimate of attributable cases is 
multiplied by the percent reduction in exposure to derive the number of 
bladder cancer cases reduced (9,300  x  .24 = 2,232 bladder cancer 
cases reduced). This assumes a linear relationship between reduction in 
TTHMs concentrations and reduction in cancer risk (e.g., 24 percent 
reduction in TTHMs concentration is associated with a 24 percent 
reduction in cancer risk). Assuming 23 percent of the bladder cancer 
cases end in fatality and 77 percent are nonfatal, the number of fatal 
bladder cancer cases reduced is 513 (2,232  x  .23) and the number of 
nonfatal bladder cancer cases is 1,719 (2,232  x  .77). Based on the 
valuation distributions described above, the estimate of benefits at 
the mean associated with reducing these bladder cancer cases is 
approximately $4 billion. It should be noted that these estimates do 
not include potential benefits from reducing other health effects (e.g, 
colon/rectal cancer and reproductive endpoints) that cannot be 
quantified at this time. As a result, EPA believes that the potential 
benefits discussed in today's rule may be a substantial underestimate 
of potential benefits that will be realized as a consequence of today's 
action. While the low end of the range cannot extend below $0, it is 
possible that the high end of the range could extend beyond $4 billion 
if the other reductions in risk could be quantified and monetized. No 
discount factor has been applied to these valuations, although there is 
likely to be a time lag between compliance with the rule and the 
realization of benefits.
    Given this wide range of potential benefits and the uncertainty 
involved in estimating the risk attributable to DBPs, EPA undertook 
five different approaches to assessing the net benefits of the Stage 1 
DBPR. These approaches are described in the net benefits section and 
should be considered both individually and in the aggregate.

E. Net Benefits Analysis

    The potential economic benefits of the Stage 1 DBPR derive from the 
increased level of public health protection and associated decreased 
level of risk. The quantification of the benefits resulting from DBP 
control is complicated by the uncertainty in the understanding of the 
health risks. Epidemiological studies, referred to previously, suggest 
an association between bladder cancer and exposure to chlorinated 
surface water; however, these risks are uncertain. The lowest estimate 
in the selected epidemiological studies of the number of new bladder 
cancer cases per year attributable to chlorinated surface water is 
1,100 cases, while the highest is 9,300 cases. EPA recognizes that 
while these risks may be real, they also could be zero. Assessment of 
risks based only on toxicological data for THMs, indicate a much lower 
risk (2 cancer cases per year at the most likely estimate, to about 100 
cases per year using the 95 percent confidence level upper bound), but 
THMs represent only a few of the many DBPs in drinking water.
    EPA explored several alternative approaches for assessing the 
benefits of the Stage 1 DBPR: Overlap of Benefit and Cost Estimates; 
Minimizing Total Social Losses; Breakeven Analysis;

[[Page 69441]]

Household Costs; and Decision-Analytic Model. A summary of the analysis 
of each approach is presented below. More detailed descriptions are 
described in the RIA (USEPA, 1998g).
    Overlap of Benefit and Cost Estimates. One method to characterize 
net benefits is to compare the relative ranges of benefits and costs. 
Conceptually, an overlap analysis tests whether there is enough of an 
overlap between the range of benefits and the range of costs for there 
to be a reasonable likelihood that benefits will exceed costs. In a 
theoretical case where the high end of the range of benefits estimates 
does not overlap the low end of the range of cost estimates, a rule 
would be difficult to justify based on traditional benefit-cost 
rationale.
    For the Stage 1 DBPR, the overlap analysis (Figures IV-1a and IV-
1b) show that there is substantial overlap in the estimates of benefits 
and costs. The range of quantified benefits extends from zero to over 
$4 billion. The zero end of the range of estimated benefits represents 
the possibility that there is essentially no health benefit from 
reducing exposure to DBPs. The other end of the range assumes there are 
9,300 bladder cancer cases per year attributable to DBPs and there is a 
24 percent annual reduction in exposure with the promulgation of the 
rule, resulting in avoidance of 2,232 cases. Assuming that number of 
avoided cases, approximately 513 would have been fatalities and would 
result in a cost savings of approximately $3 billion (each avoided 
fatality results in a cost savings of $5.6 million). Additionally, 
1,719 non-fatal cases avoided would result in a cost savings of 
approximately $1 billion (each avoided non-fatal case results in a cost 
savings of $0.6 million). The sum of the cost savings is approximately 
$4 billion. The high end of the benefits range could potentially be 
higher if other health damages are avoided. The range of cost estimates 
is significantly smaller, ranging from $500 million to $900 million 
annually. Although these cost estimates have uncertainty, the degree of 
uncertainty is of little consequence to the decisions being made given 
the scale of the uncertainty for the benefits.
    Figure IV-1b, on the other hand, indicates that while the 
quantified benefits could exceed the costs, there is the possibility 
that there could be negative net benefits if there were no health 
benefits.

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Figure IV-1a Overlap of Estimated Benefits and Costs of the Stage 1 
DBPR

    Figure IV-1b Overlap of the Ranges of the Estimated Benefits and 
Costs of the Stage 1 DBPR
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    Minimizing Total Social Losses Analysis. Minimizing Total Social 
Losses analysis, sometimes called ``minimizing regrets'' analysis, is a 
decision-aiding tool that is suited for use in situations where it is 
impossible to pin down the exact nature and extent of a risk. The basic 
premise of Minimizing Total Social Losses analysis is to estimate total 
social costs for policy alternatives over a range of plausible risk 
scenarios. The actual, or ``true'' risk is unknowable, so instead this 
analysis asks what range and level of risks could be true, and then 
evaluates the total costs to society if particular risk levels within 
that range turned out to be the ``true'' value. Total social costs 
include both the cost to implement the policy option, plus costs 
related to residual (i.e., remaining) health damages at each risk level 
after implementation of the policy option.
    Under this analysis the ``total social costs'' (water treatment 
costs plus costs of health damages still remaining after treatment) are 
calculated for three regulatory alternatives (No Action, Stage 1, and 
Strong Intervention--otherwise known as the proposed Stage 2 
requirements of the 1994 proposal) across a range of risk scenarios (< 
1; 100; 1,000; 2,500; 5,000; 7,500; and 10,000 attributable bladder 
cancer cases annually). Total social costs for each regulatory 
alternative for different risk assumptions are presented in Table IV-9. 
The results indicate that the Stage 1 DBPR has the least social cost 
among the three alternatives analyzed across the range of risks from 
2,500 through 7,500 attributable bladder cancer cases annually.
    Total ``social loss'' for each risk scenario are also indicated in 
Table IV-9. The ``social loss'' is the cost to society of making a 
wrong choice among the regulatory alternatives. It is computed as the 
difference between the total social cost (water treatment cost plus 
remaining health damages) of an alternative at a given risk scenario 
and the total social cost of the best alternative (least total social 
cost alternative for that risk scenario). The regulatory alternatives 
across the different risk levels can also be compared to see which 
alternative minimizes the maximum potential loss. The best alternative, 
by this ``mini-max'' criteria, would be the one in which the upper 
bound of potential losses is smallest.

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    Under the Stage 1 DBPR alternative, the worst loss that could 
happen would occur if the lowest end of the risk range is true. This 
would result in total social losses of $0.7 billion per year. It is 
concluded that the maximum potential loss of the Stage 1 alternative is 
smaller than that of No Action ($4.1 billion) by a factor of 6 and 
smaller than that of Strong Intervention ($2.9 billion) by a factor of 
4. Thus, the Stage 1 DBPR is the best of the 3 alternatives at 
minimizing the maximum social loss.
    The 1994 Reg. Neg. and 1997 M-DBP Advisory Committees implicitly 
applied this type of ``minimizing maximum loss'' framework when 
developing and evaluating the DBP regulatory options. In the face of 
large uncertainty regarding risk from DBPs, they decided that a 
moderate response, relying on the more cost-effective of the available 
treatment methods was appropriate as an interim step until more 
information on risk becomes available.
    Break Even Analysis. Breakeven analysis represents another approach 
to assessing the benefits of the Stage 1 DBPR given the scientific 
uncertainties. Breakeven is a standard benchmark of cost effectiveness 
and economic efficiency, and is essentially the point where the 
benefits of the Stage 1 DBPR are equal to the costs. Normally, the 
benefits and costs of an option are calculated separately and then 
compared to assess whether and by what amount benefits exceed costs. In 
the case of the Stage 1 DBPR, independently estimating benefits is 
difficult, if not impossible, because of the 10,000-fold uncertainty 
surrounding the risk. Instead, the breakeven analysis works backwards 
from those variables that are less uncertain. In this case, 
implementation costs for the rule and the monetary value associated 
with the health endpoints are used to calculate what baseline risk and 
risk reduction estimates are needed in order for the benefits, as 
measured in avoided health damages associated with bladder cancer, to 
equal the costs.
    Two important concepts for this analysis are the cost of illness 
measure and the willingness-to-pay measure. The cost of illness measure 
includes medical costs and lost wages associated with being unable to 
work as a result of illness. In comparison, willingness-to-pay measures 
how much one would pay to reduce the risk of having all the discomfort 
and costs associated with nonfatal cancer if such an option existed. 
The main difference between these two methods is that willingness-to-
pay incorporates pain and suffering, as well as changes in behavior 
into the valuation, while cost of illness does not. EPA has estimated 
the cost of a non-fatal case of bladder cancer at $121,000 using the 
cost of illness method, and at $587,500 using the willingness-to-pay 
approach.
    Assuming an annual cost of $701 million and assumptions about the 
monetary value of preventing both fatal and nonfatal bladder cancer 
cases, the Stage 1 DBPR would need to reduce 438 bladder cancer cases 
per year using the willingness-to-pay measure for nonfatal cancers or 
574 cases per year using the cost of illness measure. If exposure is 
reduced by 24 percent, the baseline number of bladder cancer cases 
attributable to DBPs in chlorinated drinking water required to break 
even would need to range from 1,820 to 2,390 new cases annually. 
Although these values are well above the range indicated by existing 
toxicological data for THMs alone, they fall within the attributable 
risk range suggested by the epidemiological studies.
    Household Cost Analysis. A fourth approach for assessing the net 
benefits of the Stage 1 DBPR is to calculate the costs per household 
for the rule. Household costs provide a common sense test of benefit/
cost relationships and are another useful benchmark for comparing the 
willingness-to-pay to reduce the possible risk posed by DBPs in 
drinking water. It is essentially a household level breakeven analysis. 
It works backwards from the cost to ask whether the implied amount of 
benefits (willingness-to-pay) needed to cover costs is a plausible 
amount.
    About 115 million households are located in service areas of 
systems affected by the Stage 1 DBPR. Of these households, 71 million 
(62 percent) are served by large surface water systems. Approximately 
4.2 million (4 percent) are served by small surface water systems. 
Large ground water systems served 24 million households (21 percent) 
and small ground water systems serve 15.7 million households (14 
percent).
    All of the households served by systems affected by the Stage 1 
DBPR will incur some additional costs (e.g., monitoring costs), even if 
the system does not have to change treatment to comply with the 
proposed rule. The costs calculated below include both monitoring and 
treatment costs.
    The cumulative distribution of household costs for all systems and 
by each system type is displayed in Figures IV-2a, IV-2b, IV-2c. The 
distributions show that the large percentage of households will incur 
small additional costs, with a small portion of systems facing higher 
costs. At the highest end of the distribution, approximately 1,400 
households served by surface water systems in the 25-100 size range 
switching to membrane technology will face an average annual cost 
increase of $400 per year ($33 per month).

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    The households have been sorted into three cost categories for the 
ease of comparison (Table IV-10). The first category includes 
households with a cost increase of less than $12 per year, less than $1 
per month. The second category contains households with costs greater 
than $12 per year, but less than $120 per year ($10 per month). The 
third category includes households with cost increases greater than 
$120 per year to $400 per year ($33 per month).
    Across all system categories (see Figure IV-2a), 95 percent of the 
households (110.1 million) fall within the first category and will 
incur less than $1 per month additional costs due to the Stage 1 DBPR. 
An additional 4 percent (4.4 million) are in the second category at 
between $1 and $10 per month cost increase and 1 percent (1.0 million) 
are in the highest category ($10-$33.40 per month).
    For households served by large surface water systems (Figure IV-
2b), 98 percent will incur less than $1 per month, 2 percent will incur 
between $1 and $10 per month, and 0.03 percent will incur greater than 
$10 per month. The highest cost ($125 annually, $10.40 monthly) is 
faced by households served by systems in the 10,000 to 25,000 size 
range implementing membrane technology.
    For households served by small surface water systems (Figure IV-
2c), 71 percent will incur less than $1 per month, 28 percent will 
incur between $1 and $10 per month, and 1 percent will incur greater 
than $10 per month. The highest cost ($400 annually, $33 monthly) is 
faced by households served by systems in the 25-100 size range 
implementing membrane technology.
    For households served by large ground water systems (Figure IV-2b), 
95 percent will incur less than $1 per month, 4 percent will incur 
between $1 and $10 per month, and 1 percent will incur greater than $10 
per month. The highest cost ($125 annually, $10.40 monthly) is faced by 
households served by systems in the 10,000 to 25,000 size range 
implementing membrane technology.
    For households served by small ground water systems (Figure IV-2c), 
91 percent will incur less than $1 per month, 5 percent will incur 
between $1 and $10 per month, and 4 percent will incur greater than $10 
per month. The highest cost ($357 annually, $29.75 monthly) is faced by 
households served by systems in the 25-100 size range implementing 
membrane technology.

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    In the small proportion of systems where household costs are shown 
to be much greater--up to several hundreds of dollars per year--these 
results are driven by the assumption that membrane technologies will be 
the selected treatment, as noted above. Additionally, two points must 
be made: (1) a number of these systems may find less expensive means of 
compliance (e.g., selection of alternative source water, purchased 
water, or consolidation with other systems); and (2) if these systems 
do install membranes, they may receive additional water quality and/or 
compliance benefits beyond those associated with DBPs. For example, 
because membranes are so effective, systems that install membranes are 
likely to incur lower compliance costs for future rulemakings.
    Given the uncertain nature of the risks associated with DBPs, 
household costs provide a common sense estimate of willingness-to-pay 
to reduce the risks: Would the average household (95 percent of 
households) be willing to pay less than $1 per month ($12 per year) to 
reduce the potential risks posed by DBPs?
    Willingness to pay studies are not available to directly answer 
this question. Taking the $1 per month figure as a measure of implied 
public health benefit at the household level, it is useful to ask what 
benefits can be identified that could balance a $1 per month 
expenditure. First, it is entirely possible that there is much more 
than a dollar-a-month's worth of tangible health benefit based on 
reduced risk of bladder cancer alone. Second, the broad exposure to 
DBPs and the possible health effects involved offer the possibility 
that there are significant additional health benefits of a tangible 
nature. However, the agency recognizes that in the small percentage of 
situations where the costs per household is between $120 to $400 per 
year, this may indeed be a difficult financial burden to meet (e.g., 
may exceed household willingness-to-pay).
    Finally, the preventive weighing and balancing of public health 
protection also provides a margin of safety--a hedge against 
uncertainties. Recent survey research conducted in the drinking water 
field provides compelling empirical evidence that the number one 
priority of water system customers is the safety of their water. 
Although definitive economic research has not been performed to 
investigate the extent of household willingness-to-pay for such a 
margin of safety, there is strong evidence from conventional customer 
survey research implying a demand for this benefit.
    Decision Analytical model. The RIA also discusses a fifth type of 
analysis in which probability functions are used to model the 
uncertainty surrounding three variables (rule cost, exposure reduction, 
and attributable bladder cancer risk) in order to derive a probability 
distribution function for annual net benefit of the Stage I rule. 
Because there is little actual data on these probability functions, 
this approach should be considered illustrative only. It is not 
discussed further here, but is discussed in Chapter 6 of the RIA for 
the Stage 1 DBPR (EPA, 1998g).
    While any one of the above analytical approaches by itself may not 
make a definitive case for the benefit-cost effectiveness for the Stage 
1 DBPR, taken collectively EPA believes they indicate that the Stage 1 
DBPR benefits to society will exceed the costs. The monetized benefits 
in the five alternatives represent only a portion of total potential 
benefits. Benefits associated with other cancer sites (rectal and 
colon) and other health endpoints (such as developmental and 
reproductive effects) could not be quantified at this time, and while 
they could be nil, they also could be quite large. Based on a careful 
weighing of the projected costs against the potential quantified and 
non-quantified benefits, EPA has determined that the benefits of the 
rule justify its costs.

F. Summary of Comments

    Many commenters expressed concern about the wide range of benefits 
given the high national cost of the rule. EPA has revised the benefits 
analysis; and while the associated uncertainties remain large, EPA 
believes the benefits of the Stage 1 DBPR justify its costs.
    Other commenters expressed concern with using the data from Morris 
et al. (1992) for quantifying benefits. They believed that the studies 
used in the meta-analysis were different in design and thus not 
appropriate to use in meta-analysis. In addition the commenters 
believed that potential confounding factors or bias may not have been 
adequately controlled in the selected studies. Others believed there 
was utility in using the meta-analysis to provide a perspective on the 
potential cancer risks. Several commenters were supportive of the Poole 
(1997) evaluation of the Morris et al. (1992) meta-analysis stating 
that they concurred that the Morris analysis should not be used for 
estimating benefits for the Stage 1 DBPR. Other commenters suggested a 
better use of the resources used to complete the Poole report would 
have been to complete a new meta-analysis using the more recent studies 
that have come out since the Morris et al. (1992) meta-analysis and 
that the Poole evaluation did not advance the science in this area. 
Several commenters were critical of the PAR analysis (described in EPA, 
1998a) used to characterize the potential baseline bladder cancer cases 
per year that could be attributable to exposure to chlorinated drinking 
water. They present several arguments including: questioning whether 
such an analysis is warranted given the inconsistencies in the studies 
used to complete the analysis; stating that the use of the term upper 
bound of any suggested risk of cancer is inappropriate because this 
does not include the potential risks from other cancer sites such as 
colon and rectal; using the assumption of causality is not warranted 
given the inconsistencies in the studies used to complete the PAR 
analysis; and the PAR analysis should include a lower bound estimate of 
zero.
    EPA agrees that the use of the Morris et al. (1992) meta-analysis 
for estimating benefits is not appropriate for the reasons cited by 
commenters (e.g., studies of different designs and discussed in more 
detail in the 1998 DBP NODA). EPA is currently considering whether a 
new meta-analysis that uses the most recent epidemiology studies would 
be useful for the Stage 2 rulemaking. The Poole (1997) report 
considered a meta analysis of the available data. Poole used several 
techniques to evaluate the data and included several new studies that 
were available at the time of his analysis. Poole concluded that the 
cancer epidemiology data considered in his evaluation should not be 
combined into a single summary estimated and that the data had limited 
utility for risk assessment purposes. More recent studies by Cantor et 
al. (1998), Doyle et al. (1997) and Freedman et al. (1997) were not 
available at the time of his evaluation.
    EPA understands commenters concerns with the PAR analysis, 
especially concerns with assuming ``causality'' in the PAR evaluation 
when it is stated in other sections of the preamble that EPA does not 
believe causality has been established. Even though causality has not 
been established, EPA is required to estimate the potential impacts of 
major regulations such as the DBP Stage 1 rule. The Agency believes it 
is appropriate to conduct the PAR analysis as described in the 1998 DBP 
NODA (EPA, 1998a), to provide estimates of the

[[Page 69452]]

potential risk that may need to be reduced. EPA agrees that the use of 
the term ``upper bound of any suggested risk'' is not appropriate 
because there are other potential risks that have not been quantified 
that may contribute to the overall risk estimates. In addition, EPA 
agrees that the estimates of the potential cancer cases should include 
zero as this is a possibility given the uncertainties in the data. EPA 
agrees that several assumptions are made in the analysis regarding the 
national extrapolation of the results and that there is insufficient 
information at this time to validate these assumptions. However, given 
the need to develop national estimates of risk, EPA believes it is 
appropriate to make these assumptions in order to provide a perspective 
on the potential risks from exposure to chlorinated surface waters.
    Commenters expressed concerns with the high costs associated with 
systems that must adopt alternative advanced technologies, especially 
for small systems. Since the 1994 proposal, the projected national 
costs for the Stage 1 DBPR have dropped significantly (as discussed 
above). This is mainly due to the revised compliance forecast and lower 
membrane technology costs. In the revised compliance forecast, fewer 
systems using surface water will need advanced technologies to comply. 
This shift to lesser use of advanced technologies to comply with the 
Stage 1 DBPR also pertains to small systems (those serving less than 
10,000 people).
    Commenters expressed concern for the high costs associated with the 
Stage 2 DBPR and whether EPA would obtain enough information to 
adequately understand the risks that might be avoided to justify such a 
rule. EPA agrees that additional health effects information is needed 
before reproposing the Stage 2 DBPR and will address this issue in the 
next round of FACA deliberations. Based on new data generated through 
research, EPA will reevaluate the Stage 2 regulations and re-propose, 
as appropriate.

V. Other Requirements

A. Regulatory Flexibility Act

1. Today's Rule
    Under the Regulatory Flexibility Act, 5 U.S.C. 601 et seq. (RFA), 
as amended by the Small Business Regulatory Enforcement Fairness Act, 
EPA generally is required to conduct a regulatory flexibility analysis 
describing the impact of the regulatory action on small entities as 
part of rulemaking. However, under section 605(b) of the RFA, if EPA 
certifies that the rule will not have a significant economic impact on 
a substantial number of small entities, EPA is not required to prepare 
a regulatory flexibility analysis.
    Throughout the 1992-93 negotiated rulemaking process for the Stage 
1 DBPR and IESWTR and in the July 1994 proposals for these rules, a 
small PWS was defined as a system serving fewer than 10,000 persons. 
This definition reflects the fact that the original 1979 standard for 
total trihalomethanes applied only to systems serving at least 10,000 
people. The definition thus recognizes that baseline conditions from 
which systems serving fewer than 10,000 people will approach 
disinfection byproduct control and simultaneous control of microbial 
pathogens is different than that for systems serving 10,000 or more 
persons. EPA again discussed this approach to the definition of a small 
system for these rules in the 1998 DBP NODA (EPA, 1998a). EPA is 
continuing to define ``small system'' for purposes of this rule and the 
IESWTR as a system which serves fewer than 10,000 people.
    The Agency has since proposed and taken comment on its intent to 
define ``small entity'' as a public water system that serves 10,000 or 
fewer persons for purposes of its regulatory flexibility assessments 
under the RFA for all future drinking water regulations. (See Consumer 
Confidence Reports Rule, 63 FR 7620, Feb. 13, 1998.) In that proposal, 
the Agency discussed the basis for its decision to use this definition 
and to use a single definition of small public water system whether the 
system was a ``small business'', ``small nonprofit organization'', or 
``small governmental jurisdiction.'' EPA also consulted with the Small 
Business Administration on the use of this definition as it relates to 
small businesses. Subsequently, the Agency has used this definition in 
developing its regulations under the Safe Drinking Water Act. This 
approach is virtually identical to the approach used in the Stage 1 
DBPR and IESWTR. Since, EPA is not able to certify that the final Stage 
1 DBPR will not have a significant economic impact on a substantial 
number of small entities, EPA has completed a final RFA and will 
publish a small entity compliance guidance to help small entities 
comply with this regulation.
2. Background and Analysis
    The Regulatory Flexibility Act requires EPA to address the 
following when completing a final RFA: (1) state succinctly the 
objectives of, and legal basis for, the final rule; (2) summarize 
public comments on the initial RFA, the Agency's assessment of those 
comments, and any changes to the rule in response to the comments; (3) 
describe, and where feasible, estimate the number of small entities to 
which the final rule will apply; (4) describe the projected reporting, 
record keeping, and other compliance requirements of the rule, 
including an estimate of the classes of small entities that will be 
subject to the requirements and the type of professional skills 
necessary for preparation of reports or records; and (5) describe the 
steps the Agency has taken to minimize the impact on small entities, 
including a statement of the reasons for selecting the chosen option 
and for rejecting other options which would alter the impact on small 
entities. EPA has considered and addressed all the above requirements 
in the Regulatory Impact Analysis (RIA) for the Stage 1 DBPR (EPA 
1998g). The following is a summary of the RFA.
    The first requirement is discussed in section I of today's rule. 
The second, third and fifth requirements are summarized below. The 
fourth requirement is discussed in V.B (Paperwork Reduction Act) and 
the Information Collection Requirement.
    Number of Small Entities Affected. EPA estimates that 69,491 
groundwater systems will be affected by the Stage 1 DBPR, with 68,171 
(98%) of these systems serving less than 10,000 persons. Of the 68,171 
small systems affected, EPA estimates that 8,323 (12%) will have to 
modify treatment to comply with the Stage 1 DBPR. Of these, 5,403 
systems (8%) will use chloramines to comply and 2,921 systems (4.3%) 
will use membranes to comply. Use of these technologies by small 
groundwater systems will result in total capital costs of $998 million 
and an annualized treatment cost of $180 million.
    EPA estimates that 6,560 surface water systems will be affected by 
the Stage 1 DBPR, with 5,165 (79%) of these systems serving less than 
10,000 persons. It is estimated that 3,616 (70%) of these small systems 
will have to modify treatment to comply with the Stage 1 DBPR and 3,459 
(67%) of these systems will use a combination of enhanced coagulation, 
chloramines, and ozone, while another 157 systems (3%) will use 
membranes. Use of these technologies by small surface water systems 
will result in total capital costs of $243 million and an annualized 
treatment cost of $46 million.
    EPA has included several provisions which will reduce the economic 
burden of compliance for these small systems. These requirements, 
discussed in greater detail in the RIA (EPA, 1998g), include:


[[Page 69453]]


--Less routine monitoring. Small systems are required to monitor less 
frequently for such contaminants as TTHMs and HAA5. Also, ground water 
systems (the large majority of small systems) are required to monitor 
less frequently than Subpart H systems (surface water systems and 
groundwater under the direct influence of surface water) of the same 
size.
--Extended compliance dates. Systems that use only ground water not 
under the direct influence of surface water serving fewer than 10,000 
people have 60 months from promulgation of this rule to comply. This is 
in contrast to large Subpart H systems which have 36 months to comply. 
These extended compliance dates will allow smaller systems to learn 
from the experience of larger systems on how to most cost effectively 
comply with the Stage 1 DBPR. In addition, larger systems will generate 
a significant amount of treatment and cost data from the ICR and in 
their efforts to achieve compliance with the Stage 1 requirements. EPA 
intends to summarize this information and make it available through 
guidance manuals (i.e., the Small Entities Guidance Manual). EPA 
believes this information will assist smaller systems in achieving 
compliance with the Stage 1 DBPR.
3. Summary of Comments
    Several commenters expressed concern with the significant economic 
burden that the Stage 1 DBPR would place on small systems. Other 
commenters suggested more flexibility be given for small systems and 
that a longer compliance period for small systems should be included in 
the final Stage 1 DBPR. Several commenters suggested small systems 
should not be included in the final Stage 1 DBPR because the costs for 
implementing the rule would exceed the potential benefits for these 
systems.
    EPA understands commenters' concerns with the potential significant 
economic burden on small systems. Because of this potential significant 
impact, EPA has provided several requirements which will reduce the 
burden on these systems. These requirements which are discussed above 
and also in greater detail in the RIA (EPA, 1998g) include: (1) less 
routine monitoring; and (2) extended compliance dates. EPA also 
believes small systems can reduce their economic burden by; (1) 
consolidation with larger systems; (2) using money from the State 
revolving fund loans; and (3) using variances and exemptions when 
needed. EPA considered an option in the development of the final rule 
for large systems to have MCLs of 80 ug/L for TTHMs and 60 ug/L for 
HAAs and for small systems to have a simple TTHM standard of 100 ug/L. 
This option was rejected because allowing small systems to comply with 
a different MCL level would not adequately protect the health of the 
population served by these systems. EPA did not consider excluding 
small systems from the Stage 1 DBPR, because these systems do not 
currently have any standards for DBPs and the Agency believed there was 
a public health concern that needed to be addressed. For a more 
detailed description of the alternatives considered in the development 
of the final rule see the final RIA (EPA, 1998g) or the final Unfunded 
Mandates Reform Act Analysis for the Stage 1 DBPR (EPA, 1998o).

B. Paperwork Reduction Act

    The Office of Management and Budget (OMB) has approved the 
information collection requirements contained in this rule under the 
provisions of the Paperwork Reduction Act, 44 U.S.C. 3501 et seq. and 
has assigned OMB control number 2040-0204.
    The information collected as a result of this rule will allow the 
States and the EPA to evaluate PWS compliance with the rule. For the 
first three years after promulgation of the Stage 1 DBPR, the major 
information requirements pertain to preparation for monitoring 
activities, and for compliance tracking. Responses to the request for 
information are mandatory (Part 141). The information collected is not 
confidential.
    EPA is required to estimate the burden on PWS for complying with 
the final rule. Burden means the total time, effort, or financial 
resources expended by persons to generate, maintain, retain, or 
disclose or provide information to or for a Federal agency. This 
includes the time needed to review instructions; develop, acquire, 
install, and utilize technology 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.
    EPA estimates that the annual burden on PWS and States for 
reporting and recordkeeping will be 314,471 hours. This is based on an 
estimate that there will be 4,631 respondents on average per year who 
will need to provide about 9,449 responses and that the average 
response will take 33 hours. The annual labor cost is estimated to be 
about $12 million. In the first 3 years after promulgation of the rule, 
only labor costs are incurred. The costs are incurred for the following 
activities: reading and understanding the rule; planning; and training.
    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 are listed in 40 CFR Part 9 and 48 CFR Chapter 15. EPA is 
amending the table in 40 CFR Part 9 of currently approved ICR control 
numbers issued by OMB for various regulations to list the information 
requirements contained in this final rule. This ICR was previously 
subject to public notice and comment prior to OMB approval. As a 
result, EPA finds that there is ``good cause'' under section 553 (b)(B) 
of the Administrative Procedures Act (5 U.S.C. 553 (b) (B)) to amend 
this table without prior notice and comment. Due to the technical 
nature of the table, further notice and comment would be unnecessary.

C. Unfunded Mandates Reform Act

1. Summary of UMRA Requirements
    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and tribal 
governments and the private sector. Under 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 to State, local, and tribal governments, in 
the aggregate, or to the private sector, of $100 million or more in any 
one year. Before promulgating an EPA rule, for which a written 
statement is needed, section 205 of the UMRA generally requires EPA to 
identify and consider a reasonable number of regulatory alternatives 
and adopt the least costly, most cost-effective or least burdensome 
alternative that achieves the objectives of the rule. The provisions of 
section 205 do not apply when they are inconsistent with applicable 
law. Moreover, section 205 allows EPA to adopt an alternative other 
than the least costly, most cost effective or least burdensome 
alternative if the Administrator publishes with the final

[[Page 69454]]

rule an explanation on 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 notification to 
potentially affected small governments, enabling officials of affected 
small governments to have meaningful and timely input in the 
development of EPA regulatory proposals with significant Federal 
intergovernmental mandates; and informing, educating, and advising 
small governments on compliance with the regulatory requirements.
2. Written Statement for Rules With Federal Mandates of $100 Million or 
More
    EPA has determined that this rule contains a Federal mandate that 
may result in expenditures of $100 million or more for State, local, 
and tribal governments, in the aggregate, and the private sector in any 
one year. Accordingly, EPA has prepared, under section 202 of the UMRA, 
a written statement addressing the following areas: (1) authorizing 
legislation; (2) cost-benefit analysis including an analysis of the 
extent to which the costs to State, local and Tribal governments will 
be paid for by the federal government; (3) estimates of future 
compliance costs and disproportionate budgetary effects; (4) macro-
economic effects; and (5) a summary of EPA's consultation with State, 
local, and Tribal governments, and a summary of their concerns, and a 
summary of EPA's evaluation of their concerns. A more detailed 
description of this analysis is presented in EPA's Unfunded Mandates 
Reform Act Analysis for the Stage 1 DBP Rule (EPA, 1998o) which is 
included in the docket for this rule.
    a. Authorizing Legislation. Today's rule is promulgated pursuant to 
Section 1412(b)(2) of the 1996 amendments to the SDWA; paragraph C of 
this section establishes a statutory deadline of November 1998 to 
promulgate this rule. This rule supersedes the TTHM Rule (EPA, 1979). 
In addition, the Stage 1 DBP rule is closely integrated with the 
IESWTR, which also has a statutory deadline of November 1998.
    b. Cost Benefit Analysis. Section IV discusses the cost and 
benefits associated with the Stage 1 DBP rule. Also, the EPA's 
Regulatory Impact Analysis of the Stage 1 Disinfectants/Disinfection 
Byproducts Rule (EPA, 1998g) contains a detailed cost benefit analysis. 
Today's rule is expected to have a total annualized cost of 
approximately $701 million using a 7 percent cost of capital. The 
analysis includes both qualitative and monetized benefits for 
improvements to health and safety. Because of scientific uncertainty 
regarding the exposure assessment and the risk assessment for DBPs, the 
Agency has used five analytical approaches to assess the benefits of 
the Stage 1 DBP. These analyses were based on the quantification of 
bladder cancer health damages avoided. However, this rule may also 
reduce colon and rectal cancers, as well as decrease adverse 
reproductive and developmental effects. This would further increase the 
benefits of this rule.
    Various Federal programs exist to provide financial assistance to 
State, local, and Tribal governments in complying with this rule. The 
Federal government provides funding to States that have primary 
enforcement responsibility for their drinking water programs through 
the Public Water Systems Supervision Grants program. Additional funding 
is available from other programs administered either by EPA or other 
Federal agencies. These include the Drinking Water State Revolving Fund 
(DWSRF) and Housing and Urban Development's Community Development Block 
Grant Program. For example, SDWA authorizes the Administrator of the 
EPA to award capitalization grants to States, which in turn can provide 
low cost loans and other types of assistance to eligible public water 
systems. The DWSRF assists public water systems with financing the 
costs of infrastructure needed to achieve or maintain compliance with 
SDWA requirements. Each State will have considerable flexibility to 
determine the design of its program and to direct funding toward its 
most pressing compliance and public health protection needs. States may 
also, on a matching basis, use up to ten percent of their DWSRF 
allotments for each fiscal year to assist in running the State drinking 
water program.
    c. Estimates of Future Compliance Costs and Disproportionate 
Budgetary Effects. To meet the UMRA requirement in section 202, EPA 
analyzed future compliance costs and possible disproportionate 
budgetary effects. The Agency believes that the cost estimates, 
indicated above and discussed in more detail in Section IV of this 
rule, accurately characterize future compliance costs of the rule.
    In regard to the disproportionate impacts, EPA considered available 
data sources in analyzing the disproportionate impacts upon geographic 
or social segments of the nation or industry. This analysis was 
difficult because impacts will most likely depend on a system's source 
water characteristics and this data is not available for all systems. 
However, it should be noted that the rule uniformly protects the health 
of all drinking water system users regardless of the size or type of 
system. Further analysis revealed that no geographic or social segment 
patterns were likely for this rule. One observation is that the 
historical pattern of development in this country led most large cities 
to be developed near rivers and other bodies of water useful for power, 
transportation, and drinking water. To the extent that this rule 
affects surface water, it in most ways reflects the distribution of 
population and geography of the nation. No rationale for 
disproportionate impacts by geography or social segment was identified. 
This analysis, therefore, developed three other measures: reviewing the 
impacts on small systems versus large systems; reviewing the costs to 
public versus private water systems; and reviewing the household costs 
of the final rule.
    First, the national impacts on small systems (those serving fewer 
than 10,000 people) versus large systems (those serving 10,000 people 
or more) is indicated in Table V-1. The higher cost to the small ground 
water systems is mostly attributable to the large number of these types 
of systems (i.e. there are 68,171 small ground water systems, 1,320 
large ground water systems, 5,165 small surface water systems, and 
1,395 large surface water surface water systems).

                    Table V-1.--Annual Cost of Compliance for Small and Large Systems ($000)*
----------------------------------------------------------------------------------------------------------------
                                                                               Small systems     Large systems
                                                                               (population <   (population  10,000)
----------------------------------------------------------------------------------------------------------------
Surface Water Systems (All).................................................         $56,804          $278,321

[[Page 69455]]

 
Ground Water System (All)...................................................         218,062           130,651
                                                                             -----------------------------------
    Total...................................................................         274,866           408,972
----------------------------------------------------------------------------------------------------------------
* Costs calculated at a 7 percent cost of capital and include one time start-up costs.

    The second measure of disproportionate impact evaluated is the 
relative total costs to public versus private water systems, by size. 
EPA believes the implementation of the rule affects both public and 
private water systems equally, with the variance in total cost by 
system size merely a function of the number of affected systems.
    The third measure, household costs, can also be used to gauge the 
impact of a regulation and to determine whether there are 
disproportionately high impacts in particular segments of the 
population. A detailed analysis of household cost impacts by system 
size and system type are presented in Section IV.E. In summary, for 
large surface water systems EPA estimates that 98 percent of households 
will incur costs of less than $1 per month while 0.3 percent of 
households will incur costs greater than $10 per month. For large 
groundwater systems, EPA estimates that 95 percent of households will 
incur costs of less than $1 per month while 1.0 percent of households 
will incur costs greater than $10 per month. For small surface water 
systems EPA estimates the 71 percent of households will incur costs of 
less than $1 per month while 1 percent of households will incur costs 
of greater than $10 per month. For small groundwater systems EPA 
estimates that 91 percent of households will incur costs of less than 
$1 per month while 4 percent of households will incur costs of greater 
than $10 per month.
    The household analysis tends to overestimate the costs per 
household because of the structure and assumptions of the methodology. 
For example, the highest per-household cost would be incurred in a 
system using membrane technology. These systems, conversely, might seek 
less costly alternatives such as point-of-use devices, selection of 
alternative water sources, or connecting into a larger regional water 
system. The overall effect is that costs are higher in smaller systems, 
and a higher percentage of those systems are publicly owned. Smaller 
systems, however, represent a larger portion of systems that are not in 
compliance with existing regulations. EPA believes that smaller systems 
incurring the highest household costs may also incur the highest 
reduction in risk. This is because smaller systems have not had to 
previously comply with a TTHMs standard of 100 ug/L. In the RIA, EPA 
estimates that on average, small systems will achieve about twice as 
much reduction in risk as achieved by larger systems (EPA,1998g).
    Based on the analysis above, EPA does not believe there will be 
disproportionate impacts on small systems, public versus private 
systems, or generally by household. A more detailed description of this 
analysis is presented in the EPA's Unfunded Mandates Reform Act 
Analysis for the Stage 1 DBP Rule (EPA,1998o).
    d. Macro-economic Effects. As required under UMRA Section 202, EPA 
is required to estimate the potential macro-economic effects of the 
regulation. Macro-economic effects tend to be measurable in nationwide 
econometric models only if the economic impact of the regulation 
reaches 0.25 percent to 0.5 percent of Gross Domestic Product (GDP). In 
1997, real GDP was $7,188 billion so a rule would have to cost at least 
$18 billion to have a measurable effect. A regulation with a smaller 
aggregate effect is unlikely to have any measurable impact unless it is 
highly focused on a particular geographic region or economic sector. 
The macro-economic effects on the national economy from the Stage 1 
DBPR should be negligible based on the fact that the total annual costs 
are about $701 million per year (at a 7 percent cost of capital) and 
the costs are not expected to be highly focused on a particular 
geographic region or sector.
    e. Summary of EPA's Consultation with State, Local, and Tribal 
Governments and Their Concerns. Under UMRA section 202, EPA is to 
provide a summary of its consultation with elected representatives (or 
their designated authorized employees) of affected State, local and 
Tribal governments in this rulemaking. Although this rule was proposed 
before UMRA became a statutory requirement, EPA initiated consultations 
with governmental entities and the private sector affected by this rule 
through various means. This included participation on a Regulatory 
Negotiation Committee chartered under the Federal Advisory Committee 
Act (FACA) in 1992-93 that included stakeholders representing State and 
local governments, public health organizations, public water systems, 
elected officials, consumer groups, and environmental groups.
    After the amendments to SDWA in 1996, the Agency initiated a second 
FACA process, similarly involving a broad range of stakeholders, and 
held meetings during 1997 to address the expedited deadline for 
promulgation of the Stage 1 DBPR in November 1998. EPA established the 
M-DBP Advisory Committee to collect, share, and analyze new data 
reviewed since the earlier Reg. Neg. process and also to build a 
consensus on the regulatory implications of this new information. The 
M-DBP Advisory Committee established a technical working group to 
assist them with the many scientific issues surrounding this rule. The 
Committee included representatives from organizations such as the 
National League of Cities, the National Association of City and County 
Health Officials, the Association of Metropolitan Water Agencies, the 
Association of State Drinking Water Administrators, and the National 
Association of Water Companies. In addition, the Agency invited the 
Native American Water Association to participate in the FACA process to 
develop this rule. Although they eventually decided not to take part, 
the Association continued to be informed of meetings and developments 
through a stakeholders mailing list.
    Stakeholders who participated in the FACA processes, as well as all 
other interested members of the public, were invited to comment on the 
proposed rule and NODAs. Also, as part of the Agency's Communication 
Strategy, EPA sent copies of the proposed rule and NODAs to many 
stakeholders, including six tribal associations.
    In addition, the Agency notified governmental entities and the 
private

[[Page 69456]]

sector of opportunities to provide input on this Stage 1 DBPR in the 
Federal Register on July 29, 1994 (59 FR 38668--EPA, 1994A), November 
3, 1997 (62 FR 59485--EPA, 1997b), and on March 31, 1998 (63 FR 15974--
EPA, 1998a). Additionally, EPA extended the comment period for the 
March 31, 1998 NODA and announced a public meeting to address new 
information. EPA received approximately 213 written comments on the 
July 29, 1994 notice, approximately 57 written comments on the November 
3, 1997 notice, and approximately 41 written comments on the March 31, 
1998 notice. Of the 213 comments received concerning the 1994 proposed 
rule, 11% were from States and 41% were from local governments. Also, 
one comment on the 1994 proposal was from a tribal group that 
represented 43 tribes. Of the 57 comments received concerning the 1997 
Notice of Data Availability, 18% were from States and 37% were from 
local governments. Of the 41 comments received on the 1998 Notice of 
Data Availability prior to the close of the comment period, 5% were 
from States and 15% were from local governments.
    The public docket for this rulemaking contains all comments 
received by the Agency and provides details about the nature of State, 
local, and tribal government's concerns. State and local governments 
raised several concerns including: the need for the Stage 1 DBPR; the 
high costs of the rule in relation to the uncertain benefits; the 
belief that not allowing predisinfection credit would increase the 
microbial risk; and the need for flexibility in implementing the Stage 
1 DPBR and IESWTR to insure the rules are implemented simultaneously. 
The one tribal comment noted that compliance would come at a cost of 
diverting funds away from other important drinking water needs such as 
maintaining drinking water infrastructure.
    EPA understands the State, local, and tribal governments concerns 
with the costs of the rule and the need to provide additional public 
health protection for the expenditure. The Agency believes the final 
Stage 1 DPBR will provide public health benefits to individuals by 
reducing their exposures to DBPs, while not requiring excessive capital 
expenditures. As discussed above, the majority of households will incur 
additional costs of less than $1 per month. As discussed in section 
III.E, the final rule maintains the existing predisinfection credit. 
Finally, in the 1997 DBP NODA (EPA, 1997b), EPA requested comment on 
four alternative schedules for complying with the Stage 1 DBPR. Most 
State and local commenters preferred the option which provides the 
maximum flexibility allowed under the SDWA for systems to comply with 
the Stage 1 DBPR, and this is the option EPA selected for the final 
rule.
    f. Regulatory Alternatives Considered. As required under Section 
205 of the UMRA, EPA considered several regulatory alternatives 
developed by the Reg Neg Committee and M-DBP Advisory Committee and 
suggested by stakeholders.
    The Reg Neg Committee considered several options including a 
proposed TTHMs MCL of 80 g/L and HAA5 MCL of 60 g/L 
for large systems (and a simple standard of 100 g/l for small 
systems). Another option called for the use of precursor removal 
technology to reduce the level of total organic carbon with alternative 
levels ranging from 4.0 to 0.5. Other options evaluated included a 80 
g/L for TTHMs, 60 g/L for HAA5, and 4.0 for TOC. 
Finally, an option was evaluated of a 80 g/L for TTHMs, 60 
g/L for HAA5, and 5.0 for TOC. The final consensus included a 
combination of MCLs which would be equal for all system size categories 
and a target TOC level. Allowing small systems to comply with a 
different MCL levels was rejected because the rule would not adequately 
protect the health of the population served by these systems. A more 
detailed description of these alternatives is discussed in the document 
Unfunded Mandates Reform Act Analysis for the Stage 1 DBPR Rule which 
can be found in the docket (EPA, 1998o).
    Other regulatory alternatives were considered by the M-DBP Advisory 
Committee and these alternatives had the overall effect of reducing the 
cost of the final rule. For example, the M-DBP Advisory Committee 
recommended maintaining the predisinfection credit after reviewing data 
which suggested that many systems could probably meet the proposed MCLs 
for DBPs while maintaining current disinfection practices. This 
decision was important because systems would have had to incur large 
capital costs to remain in compliance with disinfection requirements if 
predisinfection credits were disallowed. Thus by allowing 
predisinfection, the overall cost of the rule was lowered.
    Also, the Committee recommended exempting systems for the enhanced 
coagulation requirements based on their raw water quality. For example, 
systems with raw-water TOC of less than or equal to 2.0 mg/L and raw-
water SUVA of less than or equal to 2.0 L/mg-m would be exempt from the 
enhanced coagulation requirements. This exclusion was intended to 
promote cost-effective enhanced coagulation (i.e., obtaining 
efficiencies of TOC removal without excessive sludge production and 
associated costs).
    In conclusion, EPA believes that the alternative selected for the 
Stage 1 DBPR is the most cost-effective option that achieves the 
objectives of the rule. For a complete discussion of this issue see 
EPA's Regulatory Impact Analysis of the Stage 1 Disinfectants/
Disinfection Byproducts Rule (EPA,1998g).
3. Impacts on Small Governments
    The 1994 Stage 1 DBPR proposal was done without the benefit of the 
UMRA requirements. However, in preparation for the final rule, EPA 
conducted analysis on small government impacts and included small 
government officials or their designated representatives in the rule 
making process. The FACA processes gave a variety of stakeholders, 
including small governments, the opportunity for timely and meaningful 
participation in the regulatory development process. Representatives of 
small government organizations were on both the Reg. Neg. Committee and 
the M-DBP Advisory Committee and their representatives attended public 
stakeholder meetings. Groups such as the National Association of City 
and County Health Officials and the National League of Cities 
participated in the rulemaking process. Through such participation and 
exchange, EPA notified 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 regulatory proposals.
    In addition, EPA will educate, inform, and advise small systems 
including those run by small government about DBPR requirements. One of 
the most important components of this process is the Small Entity 
Compliance Guide, as required by the Small Business Regulatory 
Enforcement Fairness Act of 1996. This plain-English guide will explain 
what actions a small entity must take to comply with the rule. Also, 
the Agency is developing fact sheets that concisely describe various 
aspects and requirements of the DBPR.

D. National Technology Transfer and Advancement Act

    Under section 12(d) of the National Technology Transfer and 
Advancement Act (NTTAA), the Agency is required 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

[[Page 69457]]

standards (e.g., materials specifications, test methods, sampling 
procedures, business practices, etc.) that are developed or adopted by 
voluntary consensus standards bodies. Where available and potentially 
applicable voluntary consensus standards are not used by EPA, the Act 
requires the Agency to provide Congress, through OMB, an explanation of 
the reasons for not using such standards.
    EPA's process for selecting the analytical test methods is 
consistent with section 12(d) of the NTTAA. EPA performed literature 
searches to identify analytical methods from industry, academia, 
voluntary consensus standards bodies, and other parties that could be 
used to measure disinfectants, DBPs, and other parameters. In addition, 
EPA's selection of the methods benefited from the recommendations of an 
Advisory Committee established under the FACA Act to assist the Agency 
with the Stage 1 DBPR. The Committee made available additional 
technical experts who were well-versed in both existing analytical 
methods and new developments in the field.
    The results of these efforts form the basis for the analytical 
methods in today's rule which includes: eight methods for measuring 
different DBPs, of which five are EPA methods and three are voluntary 
consensus standards; nine methods for measuring disinfectants, all of 
which are voluntary consensus standards; three voluntary consensus 
methods for measuring TOC; two EPA methods for measuring bromide; one 
voluntary consensus method for measuring UV254, and both 
governmental and voluntary consensus methods for measuring alkalinity. 
Where applicable voluntary consensus standards were not approved, this 
was due to their inability to meet the data quality objectives (e.g. 
accuracy, sensitivity, quality control procedures) necessary for 
demonstration of compliance with the relevant requirement.
    In the 1997 NODA, EPA requested comment on voluntary consensus 
standards that had not been addressed and which should be considered 
for addition to the list of approved analytical methods in the final 
rule. No additional consensus methods were suggested by commenters.

E. Executive Order 12866: Regulatory Planning and Review

    Under Executive Order 12866, (58 FR 41344--EPA, 1993c) 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 entitlement, 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'' 
because it will have an annual effect on the economy of $100 million or 
more. As such, this action was submitted to OMB for review. Changes 
made in response to OMB suggestions or recommendations are documented 
in the public record.

F. Executive Order 12898: Environmental Justice

    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 has consulted with minority 
and low-income stakeholders.
    Two aspects of today's rule comply with the Environmental Justice 
Executive Order which requires the Agency to consider environmental 
justice issues in the rulemaking and to consult with Environmental 
Justice (EJ) stakeholders. They can be classified as follows: (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 applies to community water systems and nontransient noncommunity 
water systems that treat their water with a chemical disinfectant for 
either primary or residual treatment. Consequently, the health 
protection benefits this rule provides are equal across all income and 
minority groups within these communities.
    Finally, as part of EPA's responsibilities to comply with E.O. 
12898, the Agency held a stakeholder meeting on March 12, 1998 to 
address various components of pending drinking water regulations; and 
how they may impact sensitive sub-populations, minority populations, 
and low-income populations. Topics discussed included treatment 
techniques, costs and benefits, data quality, health effects, and the 
regulatory process. Participants included national, state, tribal, 
municipal, and individual stakeholders. EPA conducted the meetings by 
video conference call between eleven cities. This meeting was a 
continuation of stakeholder meetings that started in 1995 to obtain 
input on the Agency's Drinking Water Programs. The major objectives for 
the March 12, 1998 meeting were:
     Solicit ideas from EJ stakeholders on known issues 
concerning current drinking water regulatory efforts;
     Identify key issues of concern to EJ stakeholders; and
     Receive suggestions from EJ stakeholders concerning ways 
to increase representation of EJ communities in OGWDW regulatory 
efforts.
    In addition, EPA developed a plain-English guide specifically for 
this meeting to assist stakeholders in understanding the multiple and 
sometimes complex issues surrounding drinking water regulation.
    Overall, EPA believes this rule will equally protect the health of 
all minority and low-income populations served by systems regulated 
under this rule from exposure to DBPs.

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

    Executive Order 13045 applies to any rule initiated after April 21, 
1997, or proposed after April 21, 1998, that (1) is determined to be 
``economically significant'' as defined under E.O. 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.
    The final Stage 1 DBPR is not subject to the Executive Order 
because EPA published a notice of proposed rulemaking before April 21, 
1998.

[[Page 69458]]

However, EPA's policy since November 1, 1995, is to consistently and 
explicitly consider risks to infants and children in all risk 
assessments generated during its decision making process including the 
setting of standards to protect public health and the environment.
    EPA's Office of Water has historically considered risks to 
sensitive populations (including fetuses, infants, and children) in 
establishing drinking water assessments, advisories or other guidance, 
and standards (EPA, 1989c and EPA, 1991). The disinfection of public 
drinking water supplies to prevent waterborne disease is the most 
successful public health program in U.S. history. However, numerous 
chemical byproducts (DBPs) result from the reaction of chlorine and 
other disinfectants with naturally occurring organic and inorganic 
material in source water, and these may have potential health risks. 
Thus, maximizing health protection for sensitive subpopulations 
requires balancing risks to achieve the recognized benefits of 
controlling waterborne pathogens while minimizing risk of potential DBP 
toxicity. Human experience shows that waterborne disease from pathogens 
in drinking water is a major concern for children and other subgroups 
(elderly, immune compromised, pregnant women) because of their greater 
vulnerabilities (Gerba et al., 1996). Based on animal studies, there is 
also a concern for potential risks posed by DBPs to children and 
pregnant women (EPA, 1994a; EPA, 1998a).
    In developing this regulation, risks to sensitive subpopulations 
(including fetuses and children) were taken into account in the 
assessments of disinfectants and disinfection byproducts. A description 
of the data available for evaluating risks to children and the 
conclusions drawn can be found in the public docket for this rulemaking 
(EPA, 1998h). In addition, the Agency has evaluated alternative 
regulatory options and selected the option that will provide the 
greatest benefits for all people including children. See the regulatory 
impact analysis for a complete discussion of the different options 
considered. It should also be noted that the IESTWR, which accompanies 
this final rule, provides better controls of pathogens and achieves the 
goal of increasing the protection of children.

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

    In accordance with section 1412 (d) and (e) of the Act, the Agency 
submitted the proposed Stage 1 DBP rule to the Science Advisory Board, 
National Drinking Water Advisory Council (NDWAC), and the Secretary of 
Health and Human Services for their review. EPA has evaluated comments 
received from these organizations and considered them in developing the 
final Stage 1 DBP rule.

I. Executive Order 12875: Enhancing the Intergovernmental Partnership

    Under Executive Order 12875, EPA may not issue a regulation that is 
not required by statute and that creates a mandate upon a State, local 
or tribal government, unless the Federal government provides the funds 
necessary to pay the direct compliance costs incurred by those 
governments, or EPA consults with those governments. If EPA complies by 
consulting, Executive Order 12875 requires EPA to provide to the Office 
of Management and Budget a description of the extent of EPA's prior 
consultation with representatives of affected State, local and tribal 
governments, the nature of their concerns, copies of any written 
communications from the governments, and a statement supporting the 
need to issue the regulation. In addition, Executive Order 12875 
requires EPA to develop an effective process permitting elected 
officials and other representatives of State, local and tribal 
governments ``to provide meaningful and timely input in the development 
of regulatory proposals containing significant unfunded mandates.''
    EPA has concluded that this rule will create a mandate on State, 
local, and tribal governments and that the Federal government will not 
provide all of the funds necessary to pay the direct costs incurred by 
the State, local, and tribal governments in complying with the mandate. 
In developing this rule, EPA consulted with State and local governments 
to enable them to provide meaningful and timely input in the 
development of this rule. EPA also invited the Native American Water 
Association to participate in the FACA process to develop this rule, 
but they decided not to take part in the deliberations.
    As described in Section V.C.2.e, EPA held extensive meetings with a 
variety of State and local representatives, who provided meaningful and 
timely input in the development of the proposed rule. State and local 
representatives were also part of the FACA committees involved in the 
development of this rule. Summaries of the meetings have been included 
in the public docket for this rulemaking. See section V.C.2.e for 
summaries of the extent of EPA's consultation with State, local, and 
tribal governments; the nature of the government concerns; and EPA's 
position supporting the need to issue this rule.

J. Executive Order 13084: Consultation and Coordination With Indian 
Tribal Governments

    Under Executive Order 13084, EPA may not issue a regulation that is 
not required by statute, that significantly or uniquely affects the 
communities of Indian tribal governments, and that imposes substantial 
direct compliance costs on those communities, unless the Federal 
government provides the funds necessary to pay the direct compliance 
costs incurred by the tribal governments, or EPA consults with those 
governments. If EPA complies by consulting, Executive Order 13084 
requires EPA to provide to the Office of Management and Budget, in a 
separately identified section of the preamble to the rule, a 
description of the extent of EPA's prior consultation with 
representatives of affected tribal governments, a summary of the nature 
of their concerns, and a statement supporting the need to issue the 
regulation. In addition, Executive Order 13084 requires EPA to develop 
an effective process permitting elected officials and other 
representatives of Indian tribal governments ``to provide meaningful 
and timely input in the development of regulatory policies on matters 
that significantly or uniquely affect their communities.''
    EPA has concluded that this rule will significantly affect 
communities of Indian tribal governments. It will also impose 
substantial direct compliance costs on such communities, and the 
Federal government will not provide all the funds necessary to pay the 
direct costs incurred by the tribal governments in complying with the 
rule. In developing this rule, EPA consulted with representatives of 
tribal governments pursuant to both Executive Order 12875 and Executive 
Order 13084. EPA's consultation, the nature of the governments' 
concerns, and EPA's position supporting the need for this rule are 
discussed above in the preamble section that addresses compliance with 
Executive Order 12875. Specifically in developing this rule, the Agency 
invited the Native American Water Association to participate in the 
FACA process to develop this rule. Although they eventually decided not 
to take part, the Association continued to be informed of meetings and 
developments through a stakeholders mailing list. As described in 
Section V.C.2.e of the discussion on

[[Page 69459]]

UMRA, EPA held extensive meetings that provided the opportunity for 
meaningful and timely input in the development of the proposed rule. 
Summaries of the meetings have been included in the public docket for 
this rulemaking.

K. Submission to Congress and the General Accounting Office

    The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the 
Small Business Regulatory Enforcement Fairness Act of 1996, generally 
provides that before a rule may take effect, the agency promulgating 
the rule must submit a rule report, which includes a copy of the rule, 
to each House of the Congress and to the Comptroller General of the 
United States. EPA will submit a report containing this rule and other 
required information to the U.S. Senate, the U.S. House of 
Representatives, and the Comptroller General of the United States prior 
to publication of the rule in the Federal Register. A major rule cannot 
take effect until 60 days after it is published in the Federal 
Register. This rule is a ``major rule'' as defined by 5 U.S.C. 804(2). 
This rule will be effective February 16, 1999.

L. Likely Effect of Compliance With the Stage 1 DBPR on the Technical, 
Financial, and Managerial Capacity of Public Water Systems

    Section 1420(d)(3) of the SDWA as amended requires that, in 
promulgating a NPDWR, the Administrator shall include an analysis of 
the likely effect of compliance with the regulation on the technical, 
financial, and managerial capacity of public water systems. The 
following analysis has been performed to fulfill this statutory 
obligation.
    Overall water system capacity is defined in EPA guidance (EPA 816-
R-98-006) as the ability to plan for, achieve, and maintain compliance 
with applicable drinking water standards. Capacity has three 
components: technical, managerial, and financial.
    Technical capacity is the physical and operational ability of a 
water system to meet SDWA requirements. Technical capacity refers to 
the physical infrastructure of the water system, including the adequacy 
of source water and the adequacy of treatment, storage, and 
distribution infrastructure. It also refers to the ability of system 
personnel to adequately operate and maintain the system and to 
otherwise implement requisite technical knowledge. A water system's 
technical capacity can be determined by examining key issues and 
questions, including:
     Source water adequacy. Does the system have a reliable 
source of drinking water? Is the source of generally good quality and 
adequately protected?
     Infrastructure adequacy. Can the system provide water that 
meets SDWA standards? What is the condition of its infrastructure, 
including well(s) or source water intakes, treatment, storage, and 
distribution? What is the infrastructure's life expectancy? Does the 
system have a capital improvement plan?
     Technical knowledge and implementation. Is the system's 
operator certified? Does the operator have sufficient technical 
knowledge of applicable standards? Can the operator effectively 
implement this technical knowledge? Does the operator understand the 
system's technical and operational characteristics? Does the system 
have an effective operation and maintenance program?
    Managerial capacity is the ability of a water system to conduct its 
affairs in a manner enabling the system to achieve and maintain 
compliance with SDWA requirements. Managerial capacity refers to the 
system's institutional and administrative capabilities.
Managerial capacity can be assessed through key issues and questions, 
including:
     Ownership accountability. Are the system owner(s) clearly 
identified? Can they be held accountable for the system?
     Staffing and organization. Are the system operator(s) and 
manager(s) clearly identified? Is the system properly organized and 
staffed? Do personnel understand the management aspects of regulatory 
requirements and system operations? Do they have adequate expertise to 
manage water system operations? Do personnel have the necessary 
licenses and certifications?
     Effective external linkages. Does the system interact well 
with customers, regulators, and other entities? Is the system aware of 
available external resources, such as technical and financial 
assistance?
    Financial capacity is a water system's ability to acquire and 
manage sufficient financial resources to allow the system to achieve 
and maintain compliance with SDWA requirements.
    Financial capacity can be assessed through key issues and 
questions, including:
     Revenue sufficiency. Do revenues cover costs? Are water 
rates and charges adequate to cover the cost of water?
     Credit worthiness. Is the system financially healthy? Does 
it have access to capital through public or private sources?
     Fiscal management and controls. Are adequate books and 
records maintained? Are appropriate budgeting, accounting, and 
financial planning methods used? Does the system manage its revenues 
effectively?
    There are 76,051 systems affected by this rule. Of these, 12,998 
will have to modify their treatment process and undertake disinfectant 
and DBP monitoring and reporting. Some of this smaller group may also 
be required to do DBP precursor monitoring and reporting. The other 
63,063 systems will need to do disinfectant and DBP monitoring and 
reporting, but will not need to modify their treatment process. Some of 
this larger group may also be required to do DBP precursor monitoring 
and reporting.
    Systems not modifying treatment are not generally expected to 
require significantly increased technical, financial, or managerial 
capacity to comply with these new requirements. Certainly some 
individual facilities may have weaknesses in one or more of these areas 
but overall, systems should have or be able to obtain the capacity 
needed for these activities.
    Systems needing to modify treatment will employ one or more of a 
variety of steps. The steps expected to be employed by 50% or more of 
subpart H systems and by eight percent or more of ground water systems 
covered by the rule include a combination of low cost alternatives, 
including switching to chloramines for residual disinfection, moving 
the point of disinfectant application, and improving precursor removal. 
EPA estimates that less than seven percent of systems in any category 
will resort to higher cost alternatives, such as switching to ozone or 
chloramines for primary disinfection or using GAC or membranes for 
precursor removal. These higher cost alternatives may also provide 
other treatment benefits, so the cost may be somewhat offset by 
eliminating the need for technologies to remove other contaminants. 
Some of these systems may choose nontreatment alternatives such as 
consolidation with another system or changing to a higher quality water 
source.
    Furthermore, there are a number of actions that are expected to be 
taken disproportionately by smaller sized systems (that is to say, a 
greater percentage of smaller sized systems will undertake than will 
larger sized systems). These steps include increased plant staffing and 
additional staff training to understand process control strategy. Small 
systems will be required to do this since larger systems have already 
undertaken these changes to

[[Page 69460]]

some extent for compliance with the 1979 TTHM rule.
    For many systems serving less than 10,000 persons which need to 
make treatment modifications, an enhancement of technical, financial, 
and managerial capacity may likely be needed. As the preceding 
paragraph makes clear, these systems will be making structural 
improvements and enhancing laboratory and staff capacity. Larger sized 
systems have typically already made these improvements as part of 
normal operations. Meeting the requirements of the Stage 1 DBPR will 
require operating at a higher level of sophistication and in a better 
state of repair than some plants serving less than 10,000 people have 
considered acceptable in the past.
    Certainly there will be exceptions in systems serving both below 
10,000 persons and above. Some larger plants will doubtless find their 
technical, managerial, and financial capacity taxed by the new 
requirements. Likewise, some plants serving less than 10,000 persons 
will already have more than adequate technical, financial, and 
managerial capacity to meet these requirements. However, in general, 
the systems serving less than 10,000 persons needing to make treatment 
modifications will be the ones most needing to enhance their capacity.

VI. References

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Wastewater, 18th Edition. American Public Health Association, 
Washington, DC.
2. APHA. 1995. Standard Methods for the Examination of Water and 
Wastewater, 19th Edition. American Public Health Association, 
Washington DC.
3. APHA. 1996. Standard Methods for the Examination of Water and 
Wastewater, 19th Edition, Supplement. American Public Health 
Association, Washington DC.
4. ASTM. 1993. Methods D-1067-88B, D-2035-80. Annual Book of ASTM 
Standards. Vol. 11.01, American Society for Testing and Materials.
5. ASTM. 1994. Methods D-1067-92B. Annual Book of ASTM Standards. 
Vol. 11.01, American Society for Testing and Materials.
6. ASTM. 1996. Methods D-1253-86. Annual Book of ASTM Standards. 
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7. Bove, F.J., et al. 1995. Public Drinking Water Contamination and 
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32. Krasner, Stuart. April 1997. Issue Paper on Enhanced Coagulation 
to the M-DBP Advisory Committee.

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33. Kurokawa et al. 1986a. Dose-response Studies on the 
Carcinogenicity of Potassium Bromate in F344 Rats after Long-term 
Oral Administration. J. Natl. Cancer Inst. 77:977-982.
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and Water Disinfection Methods in Colorado. Am. J. Epidemiology, 
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1990. Chlorine dioxide depresses T3 uptake and delays development of 
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products, and Cancer: A Meta-Analysis. American Journal of Public 
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38. Moser, G. September 9, 1997. Letter to Yogi Patel, U.S. EPA, OW. 
Regarding the Neurodevelopment Section of the CMA Study of Chlorite.
39. NTP. 1985. National Toxicology Program. Toxicology and 
carcinogenesis studies of chlorodibromomethane in F344/N rats and 
B6C3F1 mice (gavage studies). Tech. Rep. Ser. No. 282.
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carcinogenesis studies of bromodichloromethane in F344/N rats and 
B6C3F1 mice (gavage studies). Technical Report Series No. 
321.
41. NTP. 1989. National Toxicology Program. Toxicology and 
carcinogenesis studies of bromoform in F344/N rats and 
B6C3F1 mice (gavage studies). Tech. Rep. Ser. No. 350.
42. NTP. 1990. National Toxicology Program. NTP Technical Report on 
the Toxicology and Carcinogenesis studies of chlorinated and 
chloraminated water in F344/N rats and B6C3F1 mice 
(drinking water studies). NTP TR 392, National Institutes of Health, 
474pp.
43. Orme, J. D.H. Taylor, R.D. Laurie, and R.J. Bull. 1985. Effects 
of Chlorine Dioxide on Thyroid Function in Neonatal Rats. J. Tox. 
and Environ. Health. 15:315-322.
44. OSTP. 1985. Chemical Carcinogens; A Review of the Science and 
Its Associated Principles, February 1985. Presented in Risk 
Analysis: A guide to Principles and Methods for Analyzing Health and 
Environmental Risks. Appendix G. Federal Register, March 14, 1985. 
Pages 10371-10442.
45. Owen, D. M.; Amy, G. L. and Z. K. Chowdhury. 1993. 
Characterization of Natural Organic Matter and Its Relationship to 
Treatability. AWWA Research Foundation & AWWA, Denver, CO.
46. Poole, C. 1997. Analytical Meta-Analysis of Epidemiological 
Studies of Chlorinated Drinking Water and Cancer: Quantitative 
Review and Reanalysis of the Work Published by Morris et al., Am J 
Public Health 1992:82:955-963. National Center for Environmental 
Assessment, Office of Research and Development, September 30, 1997.
47. Randtke, S. J.; Hoehn, R. C.; Knocke, W. R.; Dietrich, A. M.; 
Long, B. W.; and N. A. Wang. 1994. Comprehensive Assessment of DBP 
Precursor Removal by Enhanced Coagulation and Softening. Proc. AWWA 
Ann. Conf. (Water Quality), New York, NY, pp. 737-777.
48. Reif, J. S. et al. 1996. Reproductive and Developmental Effects 
of Disinfection By-products in Drinking Water. Environmental Health 
Prospectives. 104(10):1056-1061.
49. Sanders, V.M., B.M. Kauffman, K.L. White, K.A. Douglas, D.W. 
Barnes, L.E. Sain, T.J. Bradshaw, J.F. Borzelleca and A.E. Munson. 
1982. Toxicology of chloral hydrate in the mouse. Environ. Health 
Perspect. 44:137-146.
50. Savitz, D. A., Andrews, K. W. and L. M. Pastore. 1995. Drinking 
Water and Pregnancy Outcome in Central North Carolina: Source, 
Amount, and Trihalomethane levels. Environ. Health Perspectives. 
103(6), 592-596.
51. Shorney, H. L., Randtke, S. J., Hargette, P. H., Mann, P. D., 
Hoehn, R.C., Knocke, W. R., Dietrich, A. M. and B. W. Long. 1996. 
The Influence of Raw Water Quality on Enhanced Coagulation and 
Softening for the Removal of NOM and DBP Formation Potential, 
Proceedings 1996 AWWA Annual Conference, Toronto, Ontario, Canada.
52. Singer, P. C., Harrington, G. W., Thompson, J. D. and M. C. 
White. 1995. Enhanced Coagulation and Enhanced Softening for the 
Removal of Disinfection By-Product Precursors: An Evaluation. Report 
prepared for the AWWA Government Affairs Office, Washington, DC, by 
the Dept. of Environmental Sciences and Engineering, UNC, Chapel 
Hill, NC.
53. Singer, P. C., Harrington, G. W., Thompson, J. and M. White. 
1996. Enhanced Coagulation and Enhanced Softening for the Removal of 
Disinfection By-Product Precursors: An Evaluation, Report to AWWA 
Disinfectants/Disinfection By-Products Technical Advisory Workgroup 
of the Water Utility Council, December 1996.
54. Smith, M.K., Randall, J.L., Read, E.J., and Stober, J.A. 1989. 
Teratogenic activity of trichloroacetic acid in the rat. Teratology 
40:445-451.
55. Summers, R.S., G. Solarik, V.A. Hatcher, R.S. Isabel, and J.F. 
Stile. 1997. Analyzing the Impacts of Predisinfection Through Jar 
Testing, Proceedings, AWWA Water Quality Technology Conference, 
Denver, CO.
56. Tseng, T. and M. Edwards. 1997. Considerations in Optimizing 
Coagulation. Proc. 1996 AWWA Water Qual. Technol. Conf., Boston, 
Mass.
57. U.S. EPA. 1979. National Interim Primary Drinking Water 
Regulations; Control of Trihalomethanes in Drinking Water. Fed. 
Reg., 44:231:68624. (November 29, 1979)
58. U.S. EPA. 1983. EPA Method 310.1. Methods of Chemical Analysis 
of Water and Wastes. Envir. Monitoring Systems Laboratory, 
Cincinnati, OH. EPA 600/4-79-020. 460 pp.
59. U.S. EPA. 1986. Guidelines for Carcinogen Risk Assessment, Fed. 
Reg. 51(185):33992-34003. EPA/600/8-87/045. NTIS PB88-123997.
60. U.S. EPA. 1987. Drinking Water Regulations; Public Notification; 
Final Rule. Federal Register. Vol. 52, No. 208, Wednesday, Oct. 28, 
1987--Part II. pp. 41534-41550.
61. U.S. EPA. 1988. EPA Method 502.2. Methods for the Determination 
of Organic Compounds in Drinking Water. EPA 600/4-88-039. PB91-
231480. Revised July 1991.
62. U.S. EPA. 1989a. National Primary Drinking Water Regulations; 
Filtration, Disinfection; Turbidity, Giardia lamblia, Viruses, 
Legionella, and Heterotrophic Bacteria; Final Rule. Part II. Fed. 
Reg., 54:124:27486. (June 29, 1989)
63. U.S. EPA 1989b. National Primary Drinking Water Regulations; 
Total Coliforms (Including Fecal Coliform and E. Coli); Final Rule. 
Fed. Reg., 54:124:27544. (June 29, 1989)
64. U.S. EPA. 1989c. Review of Environmental Contaminants and 
Toxicology. USEPA. Office of Drinking Water Health Advisories, 
Volume 106. 225pp.
65. U.S. EPA. 1990. EPA Methods 551, 552. Methods for the 
Determination of Organic Compounds in Drinking Water--Supplement I. 
EPA 600/4-90-020. PB91-146027.
66 U.S. EPA. 1991. National Primary Drinking Water Regulations: 
Final Rule. Fed, reg., 56:20, January 30, 1991 3526-3597.
67. U.S. EPA. 1992. EPA Methods 524.2, 552.1. Methods for the 
Determination of Organic Compounds in Drinking Water--Supplement II. 
EPA 600/R-92/129. PB92-207703.
68. U.S. EPA. 1993a. Draft Drinking Water Health Criteria Document 
for Bromate. Office of Science and Technology, Office of Water. Sep. 
30, 1993.
69. U.S. EPA. 1993b. EPA Method 300.0. The Determination of 
Inorganic Anions by Ion Chromatography in the Manual ``Methods for 
the Determination of Inorganic Substances in Environmental 
Samples,'' EPA/600/R/93/100. NTIS, PB94120821.
70. U.S. EPA. 1993c. Executive Order 12866: Regulatory Planning and 
Review. Federal Register. Vol. 58, No. 190. October 4, 1993. 51735-
51744.
71. U.S. EPA/ILSI. 1993. A Review of Evidence on Reproductive and 
Developmental Effects of Disinfection By-Products in Drinking Water. 
Washington: U.S. Environmental Protection Agency and International 
Life Sciences Institute.

[[Page 69462]]

72. U.S. EPA. 1994a. National Primary Drinking Water Regulations; 
Disinfectants and Disinfection Byproducts; Proposed Rule. Fed. Reg., 
59:145:38668. (July 29, 1994).
73. U.S. EPA. 1994b. National Primary Drinking Water Regulations; 
Enhanced Surface Water Treatment Requirements; Proposed Rule. Fed. 
Reg., 59:145:38832. (July 29, 1994).
74. U.S. EPA. 1994c. National Primary Drinking Water Regulations; 
Monitoring Requirements for Public Drinking Water Supplies; Proposed 
Rule. Fed. Reg., 59:28:6332. (February 10, 1994).
75. U.S. EPA. 1994d. Final Draft Drinking Water Health Criteria 
Document for Chlorine Dioxide, Chlorite and Chlorate. Office of 
Science and Technology, Office of Water. March 31, 1994.
76. U.S. EPA. 1994e. Draft Drinking Water Health Criteria Document 
for Chlorine, Hypochlorous Acid and Hypochlorite Ion. Office of 
Science and Technology, Office of Water.
77. U.S. EPA. 1994f. Health and Ecological Criteria Div., OST. Final 
Draft for the Drinking Water Criteria Document on Trihalomethanes. 
Apr. 8. 1994.
78. U.S. EPA. 1994g. Draft Drinking Water Health Criteria Document 
for Chlorinated Acetic Acids/Alcohols/Aldehydes and Ketones. Office 
of Science and Technology, Office of Water.
79. U.S. EPA. 1994h. Draft Drinking Water Health Criteria Document 
for Chloramines. Office of Science and Technology, Office of Water.
80. U.S. Environmental Protection Agency. 1994i. Regulatory Impact 
Analysis of Proposed Disinfectant/Disinfection Byproduct 
Regulations. Washington, DC. EPA-68-C3-0368.
81. U.S. EPA. 1995. Methods for the Determination of Organic 
Compounds in Drinking Water. Supplement III. EPA-600/R-95/131. NTIS, 
PB95261616.
82. U.S. EPA. 1996a. National Primary Drinking Water Regulations: 
Monitoring Requirements for Public Drinking Water Supplies; Final 
Rule. Fed. Reg., 61:94:24354. (May 14, 1996)
83. U.S. EPA. 1996b. Proposed Guidelines for Carcinogen Risk 
Assessment. U.S. EPA, April 23, 1996.
84. U.S. EPA. 1997a. National Primary Drinking Water Regulations; 
Interim Enhanced Surface Water Treatment Rule; Notice of Data 
Availability; Proposed Rule. Fed. Reg., 62 (No. 212): 59486-59557. 
(November 3, 1997).
85. U.S. EPA. 1997b. National Primary Drinking Water Regulations; 
Disinfectants and Disinfection Byproducts; Notice of Data 
Availability; Proposed Rule. Fed. Reg., 62 (No. 212): 59388-59484. 
(November 3, 1997).
86. U.S. EPA. 1997c. Summaries of New Health Effects Data. Office of 
Science and Technology, Office of Water. October 1997.
87. U.S. EPA. 1997d. External Peer Review of CMA Study -2- 
Generation, EPA Contract No. 68-C7-0002, Work Assignment B-14, The 
Cadmus Group, Inc., October 9, 1997.
88. U.S. EPA. 1997e. Method 300.1. Determination of Inorganic Anions 
in Drinking Water by Ion Chromatography. Revision 1.0. USEPA 
National Exposure Research Laboratory, Cincinnati OH.
89. U.S. EPA. 1997f. Performance Based Measurement System. Notice of 
Intent. Federal Register, October 6, 1997. Vol. 62, No. 193., 52098-
52100.
90. U.S. EPA. 1997g. Manual for the Certification of Laboratories 
Analyzing Drinking Water, Fourth Edition, Office of Water Resource 
Center (RC-4100), EPA 815-B-97-001. March 1997.
91. U.S. EPA. 1998a. National Primary Drinking Water Regulations; 
Disinfectants and Disinfection Byproducts; Notice of Data 
Availability; Proposed Rule. Fed. Reg., 63 (No. 61): 15606-15692. 
(March 31, 1998).
92. U.S. EPA. 1998b. Dichloroacetic acid: Carcinogenicity 
Identification Characterization Summary. National Center for 
Environmental Assessment--Washington Office. Office of Research and 
Development. March 1998. EPA 815-B-98-010. PB 99-111387.
93. U.S. EPA. 1998c. Quantification of Bladder Cancer Risk from 
Exposure to Chlorinated Surface Water. Office of Science and 
Technology, Office of Water. November 9, 1998.
94. U.S. EPA. 1998d. Health Risk Assessment/Characterization of the 
Drinking Water Disinfection Byproduct Chlorine Dioxide and the 
Degradation Byproduct Chlorite. Office of Science and Technology, 
Office of Water. October 15, 1998. EPA 815-B-98-008. PB 99-111361.
95. U.S. EPA. 1998e. Health Risk Assessment/Characterization of the 
Drinking Water Disinfection Byproduct Bromate. Office of Science and 
Technology, Office of Water. September 30, 1998. EPA 815-B-98-007. 
PB 99-111353.
96. U.S. EPA. 1998f. Panel Report and Recommendation for Conducting 
Epidemiological Research on Possible Reproductive and Developmental 
Effects of Exposure to Disinfected Drinking Water. Office of 
Research and Development. February 12, 1998.
97. U.S. EPA. 1998g. Regulatory Impact Analysis of Final 
Disinfectant/Disinfection By-Products Regulations. Washington, D.C. 
EPA Number 815-B-98-002. PB 99-111304.
98. U.S. EPA. 1998h. Health Risks to Fetuses, Infants, and Children 
(final Stage 1 DBP Rule). Office of Science and Technology. Office 
of Water. November 19, 1998. EPA 815-B-98-009. PB 99-111379.
99. U.S. EPA. 1998i. Revisions to State Primacy Requirements To 
Implement Safe Drinking Water Act Amendments: Final Rule. Federal 
Register, Tuesday, April 28, 1998, Vol. 63, No.81, 23362-23368.
100. U.S. EPA. 1998j. Revision of Existing Variance and Exemption 
Regulations to Comply with Requirements of the Safe Drinking Water 
Act; Final Rule. Federal Register, Vol 63, No. 157. Friday, Aug. 14, 
1998. pp. 43833-43851.
101. U.S. EPA. 1998k. Cost and Technology Document for Controlling 
Disinfectants and Disinfection Byproducts. Office of Ground Water 
and Drinking Water. Washington, DC. EPA 815-R-98-014. PB 99-111486.
102. U.S. EPA. 1998l. Synthesis of the Peer-Review of Meta-analysis 
of Epidemiologic Data on Risks of Cancer from Chlorinated Drinking 
Water. National Center for Environmental Assessment, Office of 
Research and Development, February 16, 1998.
103. U.S. EPA. 1998m. NCEA Position Paper Regarding Risk Assessment 
Use of the Results from the Published Study: Morris et al. Am J 
Public Health 1992;82:955-963. National Center for Environmental 
Assessment, Office of Research and Development, October 7, 1997.
104. U.S. EPA. 1998n. A Suggested Approach for Using the Current 
Epidemiologic Literature to Estimate the Possible Cancer Risk from 
Water Chlorination, for the Purposes of the Regulatory Impact 
Analysis. ORD, National Center for Environmental Assessment. August 
27, 1998.
105. U.S. EPA. 1998o. Unfunded Mandates Reform Act Analysis for the 
Stage 1 Disinfectant and Disinfection Byproduct Rule. Office of 
Groundwater and Drinking Water.
106. U.S. EPA. 1998p. Health Risk Assessment/Characterization of the 
Drinking Water Disinfection Byproduct Chloroform. Office of Science 
and Technology, Office of Water. November 4, 1998. EPA 815-B-98-006. 
PB 99-111346.
107. U.S. EPA. 1998q. Small System Compliance Technology List for 
the Stage 1 DBP Rule. Office of Groundwater and Drinking Water. EPA 
815-R-98-017. PB 99-111510.
108. U.S. EPA. 1998r. Technologies and Costs for Point-of-Entry 
(POE) and Point-of-Use (POU) Devices for Control of Disinfection 
Byproducts. Office of Groundwater and Drinking Water. EPA 815-R-98-
016. PB 99-111502.
109. U.S. EPA. 1998s. National-Level Affordability Criteria Under 
the 1996 Amendments to the Safe Drinking Water Act. Office of 
Groundwater and Drinking Water. August 19, 1998.
110. U.S. EPA. 1998t. Variance Technology Findings for Contaminants 
Regulated Before 1996. Office of Water. September 1998. EPA 815-R-
98-003.
111. U.S. EPA. 1998u. Occurrence Assessment for Disinfectants and 
Disinfection Byproducts in Public Drinking Water Supplies. Office of 
Groundwater and Drinking Water. EPA 815-B-98-004. November 13, 1998. 
PB 99-111320.
112. USGS. 1989. Method I-1030-85. Techniques of Water Resources 
Investigations of the U.S. Geological Survey. Book 5, Chapter A-1, 
3rd ed., U.S. Government Printing Office.
113. Waller K., Swan S. H., DeLorenze G., Hopkins B., 1998. 
Trihalomethanes in drinking water and spontaneous abortion. 
Epidemiology. 9(2):134-140.

[[Page 69463]]

114. White, M. C., Thompson, D., Harrington, G. W., and P.S. Singer. 
1997. Evaluating Criteria for Enhanced Coagulation Compliance. AWWA, 
89:5:64.
115. Xie, Yuefeng. 1995. Effects of Sodium Chloride on DBP 
Analytical Results, Extended Abstract, Division of Environmental 
Chemistry, American Chemical Society Annual Conference, Chicago, IL, 
Aug. 21-26, 1995.

List of Subjects

40 CFR Part 9

    Environmental protection, Reporting and recordkeeping requirements.

40 CFR Parts 141 and 142

    Analytical methods, Drinking water, Environmental protection, 
Incorporation by reference, Intergovernmental relations, Public 
utilities, Reporting and recordkeeping requirements, Utilities, Water 
supply.

    Dated: November 30, 1998.
Carol M. Browner,
Administrator.

    For the reasons set out in the preamble, title 40, chapter I of the 
Code of Federal Regulations is amended as follows:

PART 9--[AMENDED]

    1. The authority citation for part 9 continues to read as follows:

    Authority: 7 U.S.C. 135 et seq., 136-136y; 15 U.S.C. 2001, 2003, 
2005, 2006, 2601-2671; 21 U.S.C. 331j, 346a, 348; 31 U.S.C. 9701; 33 
U.S.C. 1251 et seq., 1311, 1313d, 1314, 1318, 1321, 1326, 1330, 
1342, 1344, 1345 (d) and (e), 1361; E.O. 11735, 38 FR 21243, 3 CFR, 
1971-1975 Comp. p. 973; 42 U.S.C. 241, 242b, 243, 246, 300f, 300g, 
300g-1, 300g-2, 300g-3, 300g-4, 300g-5, 300g-6, 300j-1, 300j-2, 
300j-3, 300j-4, 300j-9, 1857 et seq., 6901-6992k, 7401-7671q, 7542, 
9601-9657, 11023, 11048.

    2. In Sec. 9.1 the table is amended by adding under the indicated 
heading: the new entries in numerical order to read as follows:


Sec. 9.1  OMB approvals under the Paperwork Reduction Act.

* * * * *

------------------------------------------------------------------------
                                                             OMB control
                      40 CFR citation                            No.
------------------------------------------------------------------------
 
                  *        *        *        *        *
National Primary Drinking Water Regulations
 
                  *        *        *        *        *
141.130-141.132............................................    2040-0204
141.134-141.135............................................    2040-0204
 
                  *        *        *        *        *
------------------------------------------------------------------------

PART 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS

    3. 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.

    4. Section 141.2 is amended by adding the following definitions in 
alphabetical order to read as follows:


Sec. 141.2  Definitions.

* * * * *
    Enhanced coagulation means the addition of sufficient coagulant for 
improved removal of disinfection byproduct precursors by conventional 
filtration treatment.
* * * * *
    Enhanced softening means the improved removal of disinfection 
byproduct precursors by precipitative softening.
* * * * *
    GAC10 means granular activated carbon filter beds with an empty-bed 
contact time of 10 minutes based on average daily flow and a carbon 
reactivation frequency of every 180 days.
* * * * *
    Haloacetic acids (five) (HAA5) mean the sum of the concentrations 
in milligrams per liter of the haloacetic acid compounds 
(monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, 
monobromoacetic acid, and dibromoacetic acid), rounded to two 
significant figures after addition.
* * * * *
    Maximum residual disinfectant level (MRDL) means a level of a 
disinfectant added for water treatment that may not be exceeded at the 
consumer's tap without an unacceptable possibility of adverse health 
effects. For chlorine and chloramines, a PWS is in compliance with the 
MRDL when the running annual average of monthly averages of samples 
taken in the distribution system, computed quarterly, is less than or 
equal to the MRDL. For chlorine dioxide, a PWS is in compliance with 
the MRDL when daily samples are taken at the entrance to the 
distribution system and no two consecutive daily samples exceed the 
MRDL. MRDLs are enforceable in the same manner as maximum contaminant 
levels under Section 1412 of the Safe Drinking Water Act. There is 
convincing evidence that addition of a disinfectant is necessary for 
control of waterborne microbial contaminants. Notwithstanding the MRDLs 
listed in Sec. 141.65, operators may increase residual disinfectant 
levels of chlorine or chloramines (but not chlorine dioxide) in the 
distribution system to a level and for a time necessary to protect 
public health to address specific microbiological contamination 
problems caused by circumstances such as distribution line breaks, 
storm runoff events, source water contamination, or cross-connections.
* * * * *
    Maximum residual disinfectant level goal (MRDLG) means the maximum 
level of a disinfectant added for water treatment at which no known or 
anticipated adverse effect on the health of persons would occur, and 
which allows an adequate margin of safety. MRDLGs are nonenforceable 
health goals and do not reflect the benefit of the addition of the 
chemical for control of waterborne microbial contaminants.
* * * * *
    Subpart H systems means public water systems using surface water or 
ground water under the direct influence of surface water as a source 
that are subject to the requirements of subpart H of this part.
* * * * *
    SUVA means Specific Ultraviolet Absorption at 254 nanometers (nm), 
an indicator of the humic content of water. It is a calculated 
parameter obtained by dividing a sample's ultraviolet absorption at a 
wavelength of 254 nm (UV 254) (in m =1) by its 
concentration of dissolved organic carbon (DOC) (in mg/L).
* * * * *
    Total Organic Carbon (TOC) means total organic carbon in mg/L 
measured using heat, oxygen, ultraviolet irradiation, chemical 
oxidants, or combinations of these oxidants that convert organic carbon 
to carbon dioxide, rounded to two significant figures.
* * * * *
    5. Section 141.12 is revised to read as follows:


Sec. 141.12  Maximum contaminant levels for total trihalomethanes.

    The maximum contaminant level of 0.10 mg/L for total 
trihalomethanes (the sum of the concentrations of bromodichloromethane, 
dibromochloromethane, tribromomethane (bromoform), and trichloromethane 
(chloroform)) applies to subpart H community water systems which serve 
a population of 10,000 people or more until December 16, 2001. This 
level applies to community water systems that use only ground water not 
under the direct influence of surface water and serve a population of 
10,000 people or more until December

[[Page 69464]]

16, 2003. Compliance with the maximum contaminant level for total 
trihalomethanes is calculated pursuant to Sec. 141.30. After December 
16, 2003, this section is no longer applicable.
    6. Section 141.30 is amended by revising the the first sentences in 
paragraphs (d) and (f) and adding paragraph (h) to read as follows:


Sec. 141.30  Total trihalomethanes sampling, analytical and other 
requirements.

* * * * *
    (d) Compliance with Sec. 141.12 shall be determined based on a 
running annual average of quarterly samples collected by the system as 
prescribed in paragraph (b)(1) or (2) of this section. * * *
* * * * *
    (f) Before a community water system makes any significant 
modifications to its existing treatment process for the purposes of 
achieving compliance with Sec. 141.12, such system must submit and 
obtain State approval of a detailed plan setting forth its proposed 
modification and those safeguards that it will implement to ensure that 
the bacteriological quality of the drinking water served by such system 
will not be adversely affected by such modification. * * *
* * * * *
    (h) The requirements in paragraphs (a) through (g) of this section 
apply to subpart H community water systems which serve a population of 
10,000 or more until December 16, 2001. The requirements in paragraphs 
(a) through (g) of this section apply to community water systems which 
use only ground water not under the direct influence of surface water 
that add a disinfectant (oxidant) in any part of the treatment process 
and serve a population of 10,000 or more until December 16, 2003. After 
December 16, 2003, this section is no longer applicable.
    7. Section 141.32 is amended by revising the heading in paragraph 
(a) introductory text, the first sentence of paragraph (a)(1)(iii) 
introductory text, and the first sentence of paragraph (c), and adding 
paragraphs (a)(1)(iii)(E) and (e) (76) through (81), to read as 
follows:


Sec. 141.32  Public notification.

* * * * *
    (a) Maximum contaminant levels (MCLs), maximum residual 
disinfectant levels (MRDLs). * * *
    (1) * * *
    (iii) For violations of the MCLs of contaminants or MRDLs of 
disinfectants that may pose an acute risk to human health, by 
furnishing a copy of the notice to the radio and television stations 
serving the area served by the public water system as soon as possible 
but in no case later than 72 hours after the violation. ***
* * * * *
    (E) Violation of the MRDL for chlorine dioxide as defined in 
Sec. 141.65 and determined according to Sec. 141.133(c)(2).
* * * * *
    (c) * * * The owner or operator of a community water system must 
give a copy of the most recent public notice for any outstanding 
violation of any maximum contaminant level, or any maximum residual 
disinfectant level, or any treatment technique requirement, or any 
variance or exemption schedule to all new billing units or new hookups 
prior to or at the time service begins.
* * * * *
    (e) * * *
    (76) Chlorine. The United States Environmental Protection Agency 
(EPA) sets drinking water standards and has determined that chlorine is 
a health concern at certain levels of exposure. Chlorine is added to 
drinking water as a disinfectant to kill bacteria and other disease-
causing microorganisms and is also added to provide continuous 
disinfection throughout the distribution system. Disinfection is 
required for surface water systems. However, at high doses for extended 
periods of time, chlorine has been shown to affect blood and the liver 
in laboratory animals. EPA has set a drinking water standard for 
chlorine to protect against the risk of these adverse effects. Drinking 
water which meets this EPA standard is associated with little to none 
of this risk and should be considered safe with respect to chlorine.
    (77) Chloramines. The United States Environmental Protection Agency 
(EPA) sets drinking water standards and has determined that chloramines 
are a health concern at certain levels of exposure. Chloramines are 
added to drinking water as a disinfectant to kill bacteria and other 
disease-causing microorganisms and are also added to provide continuous 
disinfection throughout the distribution system. Disinfection is 
required for surface water systems. However, at high doses for extended 
periods of time, chloramines have been shown to affect blood and the 
liver in laboratory animals. EPA has set a drinking water standard for 
chloramines to protect against the risk of these adverse effects. 
Drinking water which meets this EPA standard is associated with little 
to none of this risk and should be considered safe with respect to 
chloramines.
    (78) Chlorine dioxide. The United States Environmental Protection 
Agency (EPA) sets drinking water standards and has determined that 
chlorine dioxide is a health concern at certain levels of exposure. 
Chlorine dioxide is used in water treatment to kill bacteria and other 
disease-causing microorganisms and can be used to control tastes and 
odors. Disinfection is required for surface water systems. However, at 
high doses, chlorine dioxide-treated drinking water has been shown to 
affect blood in laboratory animals. Also, high levels of chlorine 
dioxide given to laboratory animals in drinking water have been shown 
to cause neurological effects on the developing nervous system. These 
neurodevelopmental effects may occur as a result of a short-term 
excessive chlorine dioxide exposure. To protect against such 
potentially harmful exposures, EPA requires chlorine dioxide monitoring 
at the treatment plant, where disinfection occurs, and at 
representative points in the distribution system serving water users. 
EPA has set a drinking water standard for chlorine dioxide to protect 
against the risk of these adverse effects.

    Note: In addition to the language in this introductory text of 
paragraph (e)(78), systems must include either the language in 
paragraph (e)(78)(i) or (e)(78)(ii) of this section. Systems with a 
violation at the treatment plant, but not in the distribution 
system, are required to use the language in paragraph (e)(78)(i) of 
this section and treat the violation as a nonacute violation. 
Systems with a violation in the distribution system are required to 
use the language in paragraph (e)(78)(ii) of this section and treat 
the violation as an acute violation.

    (i) The chlorine dioxide violations reported today are the result 
of exceedances at the treatment facility only, and do not include 
violations within the distribution system serving users of this water 
supply. Continued compliance with chlorine dioxide levels within the 
distribution system minimizes the potential risk of these violations to 
present consumers.
    (ii) The chlorine dioxide violations reported today include 
exceedances of the EPA standard within the distribution system serving 
water users. Violations of the chlorine dioxide standard within the 
distribution system may harm human health based on short-term 
exposures. Certain groups, including pregnant women, infants, and young 
children, may be especially susceptible to adverse effects of excessive 
exposure to chlorine dioxide-treated water. The purpose of this notice 
is to advise that such persons should consider reducing their risk of 
adverse effects from these chlorine dioxide violations by seeking 
alternate sources of water for human consumption until such exceedances 
are rectified. Local

[[Page 69465]]

and State health authorities are the best sources for information 
concerning alternate drinking water.
    (79) Disinfection byproducts and treatment technique for DBPs. The 
United States Environmental Protection Agency (EPA) sets drinking water 
standards and requires the disinfection of drinking water. However, 
when used in the treatment of drinking water, disinfectants react with 
naturally-occurring organic and inorganic matter present in water to 
form chemicals called disinfection byproducts (DBPs). EPA has 
determined that a number of DBPs are a health concern at certain levels 
of exposure. Certain DBPs, including some trihalomethanes (THMs) and 
some haloacetic acids (HAAs), have been shown to cause cancer in 
laboratory animals. Other DBPs have been shown to affect the liver and 
the nervous system, and cause reproductive or developmental effects in 
laboratory animals. Exposure to certain DBPs may produce similar 
effects in people. EPA has set standards to limit exposure to THMs, 
HAAs, and other DBPs.
    (80) Bromate. The United States Environmental Protection Agency 
(EPA) sets drinking water standards and has determined that bromate is 
a health concern at certain levels of exposure. Bromate is formed as a 
byproduct of ozone disinfection of drinking water. Ozone reacts with 
naturally occurring bromide in the water to form bromate. Bromate has 
been shown to produce cancer in rats. EPA has set a drinking water 
standard to limit exposure to bromate.
    (81) Chlorite. The United States Environmental Protection Agency 
(EPA) sets drinking water standards and has determined that chlorite is 
a health concern at certain levels of exposure. Chlorite is formed from 
the breakdown of chlorine dioxide, a drinking water disinfectant. 
Chlorite in drinking water has been shown to affect blood and the 
developing nervous system. EPA has set a drinking water standard for 
chlorite to protect against these effects. Drinking water which meets 
this standard is associated with little to none of these risks and 
should be considered safe with respect to chlorite.
* * * * *
    8. Subpart F is amended by revising the subpart heading and adding 
Secs. 141.53 and 141.54 to read as follows:

Subpart F--Maximum Contaminant Level Goals and Maximum Residual 
Disinfectant Level Goals

* * * * *


Sec. 141.53--Maximum contaminant level goals for disinfection 
byproducts.

    MCLGs for the following disinfection byproducts are as indicated:

------------------------------------------------------------------------
                                                                MCLG (mg/
                    Disinfection byproduct                         L)
------------------------------------------------------------------------
Chloroform....................................................   Zero
Bromodichloromethane..........................................   Zero
Bromoform.....................................................   Zero
Bromate.......................................................   Zero
Dichloroacetic acid...........................................   Zero
Trichloroacetic acid..........................................      0.3
Chlorite......................................................      0.8
Dibromochloromethane..........................................      0.06
------------------------------------------------------------------------

Sec. 141.54  Maximum residual disinfectant level goals for 
disinfectants.

    MRDLGs for disinfectants are as follows:

------------------------------------------------------------------------
          Disinfectant residual                     MRDLG(mg/L)
------------------------------------------------------------------------
Chlorine................................  4 (as Cl 2).
Chloramines.............................  4 (as Cl 2).
Chlorine dioxide........................  0.8 (as ClO2)
------------------------------------------------------------------------

    9. Subpart G is amended by revising the subpart heading and adding 
Secs. 141.64 and 141.65 to read as follows:

Subpart G--National Revised Primary Drinking Water Regulations: 
Maximum Contaminant Levels and Maximum Residual Disinfectant Levels

* * * * *


Sec. 141.64  Maximum contaminant levels for disinfection byproducts.

    (a) The maximum contaminant levels (MCLs) for disinfection 
byproducts are as follows:

------------------------------------------------------------------------
                                                                MCL (mg/
                    Disinfection byproduct                         L)
------------------------------------------------------------------------
Total trihalomethanes (TTHM)..................................     0.080
Haloacetic acids (five) (HAA5)................................     0.060
Bromate.......................................................     0.010
Chlorite......................................................     1.0
------------------------------------------------------------------------

    (b) Compliance dates. (1) CWSs and NTNCWSs. Subpart H systems 
serving 10,000 or more persons must comply with this section beginning 
December 16, 2001. 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 section beginning December 16, 
2003.
    (2) A system that is installing GAC or membrane technology to 
comply with this section may apply to the State for an extension of up 
to 24 months past the dates in paragraphs (b)(1) of this section, but 
not beyond December 16, 2003. 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 interim treatment 
requirements constitutes a violation of a National Primary Drinking 
Water Regulation.
    (c) 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 disinfection byproducts identified in paragraph 
(a) of this section:

------------------------------------------------------------------------
         Disinfection byproduct             Best available technology
------------------------------------------------------------------------
TTHM...................................  Enhanced coagulation or
                                          enhanced softening or GAC10,
                                          with chlorine as the primary
                                          and residual disinfectant
HAA5...................................  Enhanced coagulation or
                                          enhanced softening or GAC10,
                                          with chlorine as the primary
                                          and residual disinfectant.
Bromate................................  Control of ozone treatment
                                          process to reduce production
                                          of bromate.
Chlorite...............................  Control of treatment processes
                                          to reduce disinfectant demand
                                          and control of disinfection
                                          treatment processes to reduce
                                          disinfectant levels.
------------------------------------------------------------------------

Sec. 141.65  Maximum residual disinfectant levels.

    (a) Maximum residual disinfectant levels (MRDLs) are as follows:

------------------------------------------------------------------------
          Disinfectant residual                     MRDL (mg/L)
------------------------------------------------------------------------
Chlorine................................  4.0 (as Cl2).
Chloramines.............................  4.0 (as Cl2).
Chlorine dioxide........................  0.8 (as ClO2).
------------------------------------------------------------------------

    (b) Compliance dates.
    (1) CWSs and NTNCWSs. Subpart H systems serving 10,000 or more 
persons must comply with this section beginning December 16, 2001. 
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 subpart beginning December 16, 2003.
    (2) Transient NCWSs. Subpart H systems serving 10,000 or more 
persons and using chlorine dioxide as a disinfectant or oxidant must 
comply with the chlorine dioxide MRDL beginning December 16, 2001. 
Subpart H systems serving fewer than 10,000 persons and using chlorine 
dioxide as a disinfectant or oxidant and systems using only ground 
water not under the direct influence of surface water and using 
chlorine dioxide as a disinfectant or oxidant must comply with the

[[Page 69466]]

chlorine dioxide MRDL beginning December 16, 2003.
    (c) 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 
residual disinfectant levels identified in paragraph (a) of this 
section: control of treatment processes to reduce disinfectant demand 
and control of disinfection treatment processes to reduce disinfectant 
levels.
    10. A new subpart L is added to read as follows:

Subpart L--Disinfectant Residuals, Disinfection Byproducts, and 
Disinfection Byproduct Precursors

Sec.
141.130 General requirements.
141.131 Analytical requirements.
141.132 Monitoring requirements.
141.133 Compliance requirements.
141.134 Reporting and recordkeeping requirements.
141.135 Treatment technique for control of disinfection byproduct 
(DBP) precursors.


Sec. 141.130  General requirements.

    (a) The requirements of this subpart L constitute national primary 
drinking water regulations.
    (1) The regulations in this subpart establish criteria under which 
community water systems (CWSs) and nontransient, noncommunity water 
systems (NTNCWSs) which add a chemical disinfectant to the water in any 
part of the drinking water treatment process must modify their 
practices to meet MCLs and MRDLs in Secs. 141.64 and 141.65, 
respectively, and must meet the treatment technique requirements for 
disinfection byproduct precursors in Sec. 141.135.
    (2) The regulations in this subpart establish criteria under which 
transient NCWSs that use chlorine dioxide as a disinfectant or oxidant 
must modify their practices to meet the MRDL for chlorine dioxide in 
Sec. 141.65.
    (3) EPA has established MCLs for TTHM and HAA5 and treatment 
technique requirements for disinfection byproduct precursors to limit 
the levels of known and unknown disinfection byproducts which may have 
adverse health effects. These disinfection byproducts may include 
chloroform; bromodichloromethane; dibromochloromethane; bromoform; 
dichloroacetic acid; and trichloroacetic acid.
    (b) Compliance dates. (1) CWSs and NTNCWSs. Unless otherwise noted, 
systems must comply with the requirements of this subpart as follows. 
Subpart H systems serving 10,000 or more persons must comply with this 
subpart beginning December 16, 2001. 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 subpart 
beginning December 16, 2003.
    (2) Transient NCWSs. Subpart H systems serving 10,000 or more 
persons and using chlorine dioxide as a disinfectant or oxidant must 
comply with any requirements for chlorine dioxide and chlorite in this 
subpart beginning December 16, 2001. Subpart H systems serving fewer 
than 10,000 persons and using chlorine dioxide as a disinfectant or 
oxidant and systems using only ground water not under the direct 
influence of surface water and using chlorine dioxide as a disinfectant 
or oxidant must comply with any requirements for chlorine dioxide and 
chlorite in this subpart beginning December 16, 2003.
    (c) Each CWS and NTNCWS regulated under paragraph (a) of this 
section must be operated by qualified personnel who meet the 
requirements specified by the State and are included in a State 
register of qualified operators.
    (d) Control of disinfectant residuals. Notwithstanding the MRDLs in 
Sec. 141.65, systems may increase residual disinfectant levels in the 
distribution system of chlorine or chloramines (but not chlorine 
dioxide) to a level and for a time necessary to protect public health, 
to address specific microbiological contamination problems caused by 
circumstances such as, but not limited to, distribution line breaks, 
storm run-off events, source water contamination events, or cross-
connection events.


Sec. 141.131  Analytical requirements.

    (a) General. (1) Systems must use only the analytical method(s) 
specified in this section, or otherwise approved by EPA for monitoring 
under this subpart, to demonstrate compliance with the requirements of 
this subpart. These methods are effective for compliance monitoring 
February 16, 1999.
    (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, 401 M Street, SW, 
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 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 Method 300.1 
is titled USEPA Method 300.1, Determination of Inorganic Anions in 
Drinking Water by Ion Chromatography, Revision 1.0, USEPA, 1997, EPA/
600/R-98/118 (available through NTIS, PB98-169196); also 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 D, 4500-ClO2 E, 6251 B, and 5910 B shall be 
followed in accordance with Standard Methods for the Examination of 
Water and Wastewater, 19th Edition, American Public Health Association, 
1995; copies may be obtained from the American Public Health 
Association, 1015 Fifteenth Street, NW, Washington, DC 20005. 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, American Public Health 
Association, 1996; 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 edition; copies may be obtained from the American 
Society for Testing and Materials, 100 Barr Harbor Drive, West 
Conshohoken, PA 19428.
    (b) Disinfection byproducts. (1) Systems must measure disinfection 
byproducts by the methods (as modified by the footnotes) listed in the 
following table:

[[Page 69467]]



                                            Approved Methods for Disinfection Byproduct Compliance Monitoring
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                  Byproduct measured \1\
              Methodology \2\                EPA method              Standard method             -------------------------------------------------------
                                                                                                      TTHM          HAA5      Chlorite \4\     Bromate
--------------------------------------------------------------------------------------------------------------------------------------------------------
P&T/GC/ElCD & PID.........................     \3\502.2                                                     X
P&T/GC/MS.................................        524.2                                                     X
LLE/GC/ECD................................        551.1                                                     X
LLE/GC/ECD................................               6251 B                                                           X
SPE/GC/ECD................................        552.1                                                                   X
LLE/GC/ECD................................        552.2                                                                   X
Amperometric Titration....................               4500-ClO2 E                                                                    X
IC........................................        300.0                                                                                 X
IC........................................        300.1                                                                                 X             X
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ X indicates method is approved for measuring specified disinfection byproduct.
\2\ 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 extractor; IC = ion chromatography.
\3\ If TTHMs are the only analytes being measured in the sample, then a PID is not required.
\4\ Amperometric titration 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. To receive certification to conduct analyses for the 
contaminants in Sec. 141.64(a), the laboratory must carry out annual 
analyses of performance evaluation (PE) samples approved by EPA or the 
State. In these analyses of PE samples, the laboratory must achieve 
quantitative results within the acceptance limit on a minimum of 80% of 
the analytes included in each PE sample. The acceptance limit is 
defined as the 95% confidence interval calculated around the mean of 
the PE study data between a maximum and minimum acceptance limit of +/
-50% and +/-15% of the study mean.
    (c) Disinfectant residuals. (1) Systems must measure residual 
disinfectant concentrations for free chlorine, combined chlorine 
(chloramines), and chlorine dioxide by the methods listed in the 
following table:

                                            Approved Methods for Disinfectant Residual Compliance Monitoring
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                   Residual Measured \1\
                                                                                                 -------------------------------------------------------
             Methodology                    Standard  method                 ASTM method              Free        Combined        Total       Chlorine
                                                                                                    chlorine      chlorine      chlorine       dioxide
--------------------------------------------------------------------------------------------------------------------------------------------------------
Amperometric Titration..............  4500-Cl D                     D 1253-86                               X             X             X
Low Level Amperometric Titration....  4500-Cl E                                                                                         X
DPD Ferrous Titrimetric.............  4500-Cl F                                                             X             X             X
DPD Colorimetric....................  4500-Cl G                                                             X             X             X
Syringaldazin e (FACTS).............  4500-Cl H                                                             X
Iodometric Electrode................  4500-Cl I                                                                                         X
DPD.................................  4500-ClO2 D                                                                                                     X
Amperometric Method II..............  4500-ClO2 E                                                                                                     X
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ X indicates method is approved for measuring specified disinfectant residual.

    (2) If approved by the State, systems may also measure residual 
disinfectant concentrations for chlorine, chloramines, and chlorine 
dioxide by using DPD colorimetric test kits.
    (3) A party approved by EPA or the State must measure residual 
disinfectant concentration.
    (d) Additional analytical methods. Systems required to analyze 
parameters not included in paragraphs (b) and (c) of this section must 
use the following methods. A party approved by EPA or the State must 
measure these parameters.
    (1) Alkalinity. All methods allowed in Sec. 141.89(a) for measuring 
alkalinity.
    (2) Bromide. EPA Method 300.0 or EPA Method 300.1.
    (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). TOC samples may not be filtered prior to 
analysis. TOC samples must either be analyzed or must be acidified to 
achieve pH less than 2.0 by minimal addition of phosphoric or sulfuric 
acid as soon as practical after sampling, not to exceed 24 hours. 
Acidified TOC samples must be analyzed within 28 days.
    (4) Specific Ultraviolet Absorbance (SUVA). SUVA is equal to the UV 
absorption at 254nm (UV254) (measured in m-\1\ divided by 
the dissolved organic carbon (DOC) concentration (measured as mg/L). In 
order to determine SUVA, it is necessary to separately measure 
UV254 and DOC. When determining SUVA, systems must use the 
methods stipulated in paragraph (d)(4)(i) of this section to measure 
DOC and the method stipulated in paragraph (d)(4)(ii) of this section 
to measure UV254. SUVA must be determined on water prior to 
the addition of disinfectants/oxidants by the system. DOC and 
UV254 samples used to determine a SUVA value must be taken 
at the same time and at the same location.
    (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

[[Page 69468]]

5310 D (Wet-Oxidation Method). Prior to analysis, DOC samples must be 
filtered through a 0.45 m pore-diameter filter. 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. DOC samples must be filtered 
through the 0.45 m pore-diameter filter prior to 
acidification. DOC samples must either be analyzed or must be acidified 
to achieve pH less than 2.0 by minimal addition of phosphoric or 
sulfuric acid as soon as practical after sampling, not to exceed 48 
hours. Acidified DOC samples must be analyzed within 28 days.
    (ii) Ultraviolet Absorption at 254 nm (UV254). Method 
5910 B (Ultraviolet Absorption Method). 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 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.
    (5) pH. All methods allowed in Sec. 141.23(k)(1) for measuring pH.


Sec. 141.132  Monitoring requirements.

    (a) General requirements. (1) Systems must take all samples during 
normal operating conditions.
    (2) Systems 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(f)(5) of this chapter.
    (3) Failure to monitor in accordance with the monitoring plan 
required under paragraph (f) of this section is a monitoring violation.
    (4) Failure to monitor will be treated as a violation for the 
entire period covered by the annual average where compliance is based 
on a running annual average of monthly or quarterly samples or averages 
and the system's failure to monitor makes it impossible to determine 
compliance with MCLs or MRDLs.
    (5) Systems may use only data collected under the provisions of 
this subpart or subpart M of this part to qualify for reduced 
monitoring.
    (b) Monitoring requirements for disinfection byproducts. (1) TTHMs 
and HAA5. (i) Routine monitoring. Systems must monitor at the frequency 
indicated in the following table:

                                 Routine Monitoring Frequency for TTHM and HAA5
----------------------------------------------------------------------------------------------------------------
                                          Minimum monitoring
           Type of system                     frequency             Sample location in the distribution system
----------------------------------------------------------------------------------------------------------------
Subpart H system serving at least    Four water samples per       At least 25 percent of all samples collected
 10,000 persons.                      quarter per treatment        each quarter at locations representing
                                      plant.                       maximum residence time. Remaining samples
                                                                   taken at locations representative of at least
                                                                   average residence time in the distribution
                                                                   system and representing the entire
                                                                   distribution system, taking into account
                                                                   number of persons served, different sources
                                                                   of water, and different treatment methods.\1\
Subpart H system serving from 500    One water sample per         Locations representing maximum residence
 to 9,999 persons.                    quarter per treatment        time.\1\
                                      plant.
Subpart H system serving fewer than  One sample per year per      Locations representing maximum residence
 500 persons.                         treatment plant during       time.\1\ If the sample (or average of annual
                                      month of warmest water       samples, if more than one sample is taken)
                                      temperature.                 exceeds MCL, system must increase monitoring
                                                                   to one sample per treatment plant per
                                                                   quarter, taken at a point reflecting the
                                                                   maximum residence time in the distribution
                                                                   system, until system meets reduced monitoring
                                                                   criteria in paragraph (c) of this section.
System using only ground water not   One water sample per         Locations representing maximum residence
 under direct influence of surface    quarter per treatment        time.\1\
 water using chemical disinfectant    plant \2\.
 and serving at least 10,000
 persons.
System using only ground water not   One sample per year per      Locations representing maximum residence
 under direct influence of surface    treatment plant \2\ during   time.\1\ If the sample (or average of annual
 water using chemical disinfectant    month of warmest water       samples, if more than one sample is taken)
 and serving fewer than 10,000        temperature.                 exceeds MCL, system must increase monitoring
 persons.                                                          to one sample per treatment plant per
                                                                   quarter, taken at a point reflecting the
                                                                   maximum residence time in the distribution
                                                                   system, until system meets criteria in
                                                                   paragraph (c) of this section for reduced
                                                                   monitoring.
----------------------------------------------------------------------------------------------------------------
\1\ If a system elects to sample more frequently than the minimum required, at least 25 percent of all samples
  collected each quarter (including those taken in excess of the required frequency) must be taken at locations
  that represent the maximum residence time of the water in the distribution system. The remaining samples must
  be taken at locations representative of at least average residence time in the distribution system.
\2\ Multiple wells drawing water from a single aquifer may be considered one treatment plant for determining the
  minimum number of samples required, with State approval in accordance with criteria developed under Sec.
  142.16(f)(5) of this chapter.

    (ii) Systems may reduce monitoring, except as otherwise provided, 
in accordance with the following table:

[[Page 69469]]



                                 Reduced Monitoring Frequency for TTHM and HAA5
----------------------------------------------------------------------------------------------------------------
                                      You may reduce monitoring
         If you are a . . .            if you have monitored at                    To this level
                                     least one year and your . .
--------------------------------------------------.-------------------------------------------------------------
Subpart H system serving at least    TTHM annual average 0.040 mg/L and HAA5       distribution system location reflecting
 water annual average TOC level,      annual average 0.030 mg/L.
 eq>4.0 mg/L.
Subpart H system serving from 500    TTHM annual average 0.040 mg/L and HAA5       distribution system location reflecting
 source water annual average TOC      annual average 0.030 mg/L.               warmest water temperature. NOTE: Any Subpart
 thn-eq>4.0 mg/L.                                                  H system serving fewer than 500 persons may
                                                                   not reduce its monitoring to less than one
                                                                   sample per treatment plant per year.
System using only ground water not   TTHM annual average 0.040 mg/L and HAA5       distribution system location reflecting
 water using chemical disinfectant    annual average 0.030 mg/L.               warmest water temperature
 persons.
System using only ground water not   TTHM annual average 0.040 mg/L and HAA5       monitoring cycle at distribution system
 water using chemical disinfectant    annual average 0.030 mg/L for two        during month of warmest water temperature,
 persons.                             consecutive years OR TTHM    with the three-year cycle beginning on
                                      annual average 0.020 mg/L and HAA5       qualifies for reduced monitoring.
                                      annual average 0.015 mg/L for one year.
----------------------------------------------------------------------------------------------------------------

    (iii) Systems on a reduced monitoring schedule may remain on that 
reduced schedule as long as the average of all samples taken in the 
year (for systems which must monitor quarterly) or the result of the 
sample (for systems which must monitor no more frequently than 
annually) is no more than 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5, 
respectively. Systems that do not meet these levels must resume 
monitoring at the frequency identified in paragraph (b)(1)(i) of this 
section in the quarter immediately following the quarter in which the 
system exceeds 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5, 
respectively.
    (iv) The State may return a system to routine monitoring at the 
State's discretion.
    (2) Chlorite. Community and nontransient noncommunity water systems 
using chlorine dioxide, for disinfection or oxidation, must conduct 
monitoring for chlorite.
    (i) Routine monitoring. (A) Daily monitoring. Systems must take 
daily samples at the entrance to the distribution system. For any daily 
sample that exceeds the chlorite MCL, the system must take additional 
samples in the distribution system the following day at the locations 
required by paragraph (b)(2)(ii) of this section, in addition to the 
sample required at the entrance to the distribution system.
    (B) Monthly monitoring. Systems must take a three-sample set each 
month in the distribution system. The system must take one sample at 
each of the following locations: near the first customer, at a location 
representative of average residence time, and at a location reflecting 
maximum residence time in the distribution system. Any additional 
routine sampling must be conducted in the same manner (as three-sample 
sets, at the specified locations). The system may use the results of 
additional monitoring conducted under paragraph (b)(2)(ii) of this 
section to meet the requirement for monitoring in this paragraph.
    (ii) Additional monitoring. On each day following a routine sample 
monitoring result that exceeds the chlorite MCL at the entrance to the 
distribution system, the system is required to take three chlorite 
distribution system samples at the following locations: as close to the 
first customer as possible, in a location representative of average 
residence time, and as close to the end of the distribution system as 
possible (reflecting maximum residence time in the distribution 
system).
    (iii) Reduced monitoring. (A) Chlorite monitoring at the entrance 
to the distribution system required by paragraph (b)(2)(i)(A) of this 
section may not be reduced.
    (B) Chlorite monitoring in the distribution system required by 
paragraph (b)(2)(i)(B) of this section may be reduced to one three-
sample set per quarter after one year of monitoring where no individual 
chlorite sample taken in the distribution system under paragraph 
(b)(2)(i)(B) of this section has exceeded the chlorite MCL and the 
system has not been required to conduct monitoring under paragraph 
(b)(2)(ii) of this section. The system may remain on the reduced 
monitoring schedule until either any of the three individual chlorite 
samples taken quarterly in the distribution system under paragraph 
(b)(2)(i)(B) of this section exceeds the chlorite MCL or the system is 
required to conduct monitoring under paragraph (b)(2)(ii) of this 
section, at which time the system must revert to routine monitoring.
    (3) Bromate. (i) Routine monitoring. Community and nontransient 
noncommunity systems using ozone, for disinfection or oxidation, must 
take one sample per month for each treatment plant in the system using 
ozone. Systems must take samples monthly at the entrance to the 
distribution system while the ozonation system is operating under 
normal conditions.
    (ii) Reduced monitoring. Systems required to analyze for bromate 
may reduce monitoring from monthly to once per quarter, if the system 
demonstrates that the average source water bromide concentration is 
less than 0.05 mg/L based upon 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 upon representative monthly measurements. If the running annual 
average source water bromide concentration is 0.05 mg/L, the 
system must resume routine monitoring

[[Page 69470]]

required by paragraph (b)(3)(i) of this section.
    (c) Monitoring requirements for disinfectant residuals. (1) 
Chlorine and chloramines. (i) Routine monitoring. Systems must measure 
the residual disinfectant level at the same points in the distribution 
system and at the same time as total coliforms are sampled, as 
specified in Sec. 141.21. Subpart H systems may use the results of 
residual disinfectant concentration sampling conducted under 
Sec. 141.74(b)(6)(i) for unfiltered systems or Sec. 141.74(c)(3)(i) for 
systems which filter, in lieu of taking separate samples.
    (ii) Reduced monitoring. Monitoring may not be reduced.
    (2) Chlorine dioxide. (i) Routine monitoring. Community, 
nontransient noncommunity, and transient noncommunity water systems 
that use chlorine dioxide for disinfection or oxidation must take daily 
samples at the entrance to the distribution system. For any daily 
sample that exceeds the MRDL, the system must take samples in the 
distribution system the following day at the locations required by 
paragraph (c)(2)(ii) of this section, in addition to the sample 
required at the entrance to the distribution system.
    (ii) Additional monitoring. On each day following a routine sample 
monitoring result that exceeds the MRDL, the system is required to take 
three chlorine dioxide distribution system samples. If chlorine dioxide 
or chloramines are used to maintain a disinfectant residual in the 
distribution system, or if chlorine is used to maintain a disinfectant 
residual in the distribution system and there are no disinfection 
addition points after the entrance to the distribution system (i.e., no 
booster chlorination), the system must take three samples as close to 
the first customer as possible, at intervals of at least six hours. If 
chlorine is used to maintain a disinfectant residual in the 
distribution system and there are one or more disinfection addition 
points after the entrance to the distribution system (i.e., booster 
chlorination), the system must take one sample at each of the following 
locations: as close to the first customer as possible, in a location 
representative of average residence time, and as close to the end of 
the distribution system as possible (reflecting maximum residence time 
in the distribution system).
    (iii) Reduced monitoring. Chlorine dioxide monitoring may not be 
reduced.
    (d) Monitoring requirements for disinfection byproduct precursors 
(DBPP). (1) Routine monitoring. Subpart H systems which use 
conventional filtration treatment (as defined in Sec. 141.2) must 
monitor each treatment plant for TOC no later than the point of 
combined filter effluent turbidity monitoring and representative of the 
treated water. All systems required to monitor under this paragraph 
(d)(1) must also monitor for TOC in the source water prior to any 
treatment at the same time as monitoring for TOC in the treated water. 
These samples (source water and treated water) are referred to as 
paired samples. At the same time as the source water sample is taken, 
all systems must monitor for alkalinity in the source water prior to 
any treatment. Systems must take one paired sample and one source water 
alkalinity sample per month per plant at a time representative of 
normal operating conditions and influent water quality.
    (2) Reduced monitoring. Subpart H systems with an average treated 
water TOC of less than 2.0 mg/L for two consecutive years, or less than 
1.0 mg/L for one year, may reduce monitoring for both TOC and 
alkalinity to one paired sample and one source water alkalinity sample 
per plant per quarter. The system must revert to routine monitoring in 
the month following the quarter when the annual average treated water 
TOC 2.0 mg/L.
    (e) Bromide. Systems required to analyze for bromate may reduce 
bromate monitoring from monthly to once per quarter, if the system 
demonstrates that the average source water bromide concentration is 
less than 0.05 mg/L based upon representative monthly measurements for 
one year. The system must continue bromide monitoring to remain on 
reduced bromate monitoring.
    (f) Monitoring plans. Each system required to monitor under this 
subpart must develop and implement a monitoring plan. The system must 
maintain the plan and make it available for inspection by the State and 
the general public no later than 30 days following the applicable 
compliance dates in Sec. 141.130(b). All Subpart H systems serving more 
than 3300 people must submit a copy of the monitoring plan to the State 
no later than the date of the first report required under Sec. 141.134. 
The State may also require the plan to be submitted by any other 
system. After review, the State may require changes in any plan 
elements. The plan must include at least the following elements.
    (1) Specific locations and schedules for collecting samples for any 
parameters included in this subpart.
    (2) How the system will calculate compliance with MCLs, MRDLs, and 
treatment techniques.
    (3) If approved for monitoring as a consecutive system, or if 
providing water to a consecutive system, under the provisions of 
Sec. 141.29, the sampling plan must reflect the entire distribution 
system.


Sec. 141.133  Compliance requirements.

    (a) General requirements. (1) Where compliance is based on a 
running annual average of monthly or quarterly samples or averages and 
the system's failure to monitor for TTHM, HAA5, or bromate, this 
failure to monitor will be treated as a monitoring violation for the 
entire period covered by the annual average. Where compliance is based 
on a running annual average of monthly or quarterly samples or averages 
and the system's failure to monitor makes it impossible to determine 
compliance with MRDLs for chlorine and chloramines, this failure to 
monitor will be treated as a monitoring violation for the entire period 
covered by the annual average.
    (2) All samples taken and analyzed under the provisions of this 
subpart must be included in determining compliance, even if that number 
is greater than the minimum required.
    (3) If, during the first year of monitoring under Sec. 141.132, any 
individual quarter's average will cause the running annual average of 
that system to exceed the MCL, the system is out of compliance at the 
end of that quarter.
    (b) Disinfection byproducts. (1) TTHMs and HAA5. (i) For systems 
monitoring quarterly, compliance with MCLs in Sec. 141.64 must be based 
on a running annual arithmetic average, computed quarterly, of 
quarterly arithmetic averages of all samples collected by the system as 
prescribed by Sec. 141.132(b)(1). If the running annual arithmetic 
average of quarterly averages covering any consecutive four-quarter 
period exceeds the MCL, the system is in violation of the MCL and must 
notify the public pursuant to Sec. 141.32, in addition to reporting to 
the State pursuant to Sec. 141.134. If a PWS fails to complete four 
consecutive quarters' monitoring, compliance with the MCL for the last 
four-quarter compliance period must be based on an average of the 
available data.
    (ii) For systems monitoring less frequently than quarterly, 
compliance must be based on an average of samples taken that year under 
the provisions of Sec. 141.132(b)(1). If the average of these samples 
exceeds the MCL, the system must increase monitoring to once per 
quarter per treatment plant.
    (iii) Systems on a reduced monitoring schedule whose annual average 
exceeds the MCL will revert to routine monitoring immediately. These 
systems

[[Page 69471]]

will not be considered in violation of the MCL until they have 
completed one year of routine monitoring.
    (2). Bromate. Compliance must be based on a running annual 
arithmetic average, computed quarterly, of monthly samples (or, for 
months in which the system takes more than one sample, the average of 
all samples taken during the month) collected by the system as 
prescribed by Sec. 141.132(b)(3). If the average of samples covering 
any consecutive four-quarter period exceeds the MCL, the system is in 
violation of the MCL and must notify the public pursuant to 
Sec. 141.32, in addition to reporting to the State pursuant to 
Sec. 141.134. If a PWS fails to complete 12 consecutive months' 
monitoring, compliance with the MCL for the last four-quarter 
compliance period must be based on an average of the available data.
    (3) Chlorite. Compliance must be based on an arithmetic average of 
each three sample set taken in the distribution system as prescribed by 
Sec. 141.132(b)(2)(i)(B) and Sec. 141.132(b)(2)(ii). If the arithmetic 
average of any three sample set exceeds the MCL, the system is in 
violation of the MCL and must notify the public pursuant to 
Sec. 141.32, in addition to reporting to the State pursuant to 
Sec. 141.134.
    (c) Disinfectant residuals. (1) Chlorine and chloramines. (i) 
Compliance must be based on a running annual arithmetic average, 
computed quarterly, of monthly averages of all samples collected by the 
system under Sec. 141.132(c)(1). If the average of quarterly averages 
covering any consecutive four-quarter period exceeds the MRDL, the 
system is in violation of the MRDL and must notify the public pursuant 
to Sec. 141.32, in addition to reporting to the State pursuant to 
Sec. 141.134.
    (ii) In cases where systems switch between the use of chlorine and 
chloramines for residual disinfection during the year, compliance must 
be determined by including together all monitoring results of both 
chlorine and chloramines in calculating compliance. Reports submitted 
pursuant to Sec. 141.134 must clearly indicate which residual 
disinfectant was analyzed for each sample.
    (2) Chlorine dioxide. (i) Acute violations. Compliance must be 
based on consecutive daily samples collected by the system under 
Sec. 141.132(c)(2). If any daily sample taken at the entrance to the 
distribution system exceeds the MRDL, and on the following day one (or 
more) of the three samples taken in the distribution system exceed the 
MRDL, the system is in violation of the MRDL and must take immediate 
corrective action to lower the level of chlorine dioxide below the MRDL 
and must notify the public pursuant to the procedures for acute health 
risks in Sec. 141.32(a)(1)(iii)(E). Failure to take samples in the 
distribution system the day following an exceedance of the chlorine 
dioxide MRDL at the entrance to the distribution system will also be 
considered an MRDL violation and the system must notify the public of 
the violation in accordance with the provisions for acute violations 
under Sec. 141.32(a)(1)(iii)(E).
    (ii) Nonacute violations. Compliance must be based on consecutive 
daily samples collected by the system under Sec. 141.132(c)(2). If any 
two consecutive daily samples taken at the entrance to the distribution 
system exceed the MRDL and all distribution system samples taken are 
below the MRDL, the system is in violation of the MRDL and must take 
corrective action to lower the level of chlorine dioxide below the MRDL 
at the point of sampling and will notify the public pursuant to the 
procedures for nonacute health risks in Sec. 141.32(e)(78). Failure to 
monitor at the entrance to the distribution system the day following an 
exceedance of the chlorine dioxide MRDL at the entrance to the 
distribution system is also an MRDL violation and the system must 
notify the public of the violation in accordance with the provisions 
for nonacute violations under Sec. 141.32(e)(78).
    (d) Disinfection byproduct precursors (DBPP). Compliance must be 
determined as specified by Sec. 141.135(b). Systems may begin 
monitoring to determine whether Step 1 TOC removals can be met 12 
months prior to the compliance date for the system. This monitoring is 
not required and failure to monitor during this period is not a 
violation. However, any system that does not monitor during this 
period, and then determines in the first 12 months after the compliance 
date that it is not able to meet the Step 1 requirements in 
Sec. 141.135(b)(2) and must therefore apply for alternate minimum TOC 
removal (Step 2) requirements, is not eligible for retroactive approval 
of alternate minimum TOC removal (Step 2) requirements as allowed 
pursuant to Sec. 141.135(b)(3) and is in violation. Systems may apply 
for alternate minimum TOC removal (Step 2) requirements any time after 
the compliance date.


Sec. 141.134  Reporting and recordkeeping requirements.

    (a) Systems required to sample quarterly or more frequently must 
report to the State within 10 days after the end of each quarter in 
which samples were collected, notwithstanding the provisions of 
Sec. 141.31. Systems required to sample less frequently than quarterly 
must report to the State within 10 days after the end of each 
monitoring period in which samples were collected.
    (b) Disinfection byproducts. Systems must report the information 
specified in the following table:

------------------------------------------------------------------------
            If you are a...                   You must report...\1\
------------------------------------------------------------------------
System monitoring for TTHM and HAA5      (1) The number of samples taken
 under the requirements of Secs.          during the last quarter.
 141.132(b) on a quarterly or more
 frequent basis.
                                         (2) The location, date, and
                                          result of each sample taken
                                          during the last quarter.
                                         (3) The arithmetic average of
                                          all samples taken in the last
                                          quarter.
                                         (4) The annual arithmetic
                                          average of the quarterly
                                          arithmetic averages of this
                                          section for the last four
                                          quarters.
                                         (5) Whether the MCL was
                                          exceeded.
System monitoring for TTHMs and HAA5     (1) The number of samples taken
 under the requirements of Secs.          during the last year.
 141.132(b) less frequently than
 quarterly (but at least annually).
                                         (2) The location, date, and
                                          result of each sample taken
                                          during the last quarter.
                                         (3) The arithmetic average of
                                          all samples taken over the
                                          last year.
                                         (4) Whether the MCL was
                                          exceeded.
System monitoring for TTHMs and HAA5     (1) The location, date, and
 under the requirements of Sec.           result of the last sample
 141.132(b) less frequently than          taken.
 annually.
                                         (2) Whether the MCL was
                                          exceeded.

[[Page 69472]]

 
System monitoring for chlorite under     (1) The number of samples taken
 the requirements of Sec.  141.132(b).    each month for the last 3
                                          months.
                                         (2) The location, date, and
                                          result of each sample taken
                                          during the last quarter.
                                         (3) For each month in the
                                          reporting period, the
                                          arithmetic average of all
                                          samples taken in the month.
                                         (4) Whether the MCL was
                                          exceeded, and in which month
                                          it was exceeded.
System monitoring for bromate under the  (1) The number of samples taken
 requirements of Sec.  141.132(b).        during the last quarter.
                                         (2) The location, date, and
                                          result of each sample taken
                                          during the last quarter.
                                         (3) The arithmetic average of
                                          the monthly arithmetic
                                          averages of all samples taken
                                          in the last year.
                                         (4) Whether the MCL was
                                          exceeded.
------------------------------------------------------------------------

    (c) Disinfectants. Systems must report the information specified in 
the following table:

------------------------------------------------------------------------
            If you are a...                   You must report...\1\
------------------------------------------------------------------------
System monitoring for chlorine or        (1) The number of samples taken
 chloramines under the requirements of    during each month of the last
 Sec.  141.132(c).                        quarter.
                                         (2) The monthly arithmetic
                                          average of all samples taken
                                          in each month for the last 12
                                          months.
                                         (3) The arithmetic average of
                                          all monthly averages for the
                                          last 12 months.
                                         (4) Whether the MRDL was
                                          exceeded.
System monitoring for chlorine dioxide   (1) The dates, results, and
 under the requirements of Sec.           locations of samples taken
 141.132(c).                              during the last quarter.
                                         (2) Whether the MRDL was
                                          exceeded.
                                         (3) Whether the MRDL was
                                          exceeded in any two
                                          consecutive daily samples and
                                          whether the resulting
                                          violation was acute or
                                          nonacute.
------------------------------------------------------------------------
\1\ The State may choose to perform calculations and determine whether
  the MRDL was exceeded, in lieu of having the system report that
  information.

    (d) Disinfection byproduct precursors and enhanced coagulation or 
enhanced softening. Systems must report the information specified in 
the following table:

------------------------------------------------------------------------
           If you are a . . .                You must report . . .\1\
------------------------------------------------------------------------
System monitoring monthly or quarterly   (1) The number of paired
 for TOC under the requirements of Sec.   (source water and treated
  141.132(d) and required to meet the     water, prior to continuous
 enhanced coagulation or enhanced         disinfection) samples taken
 softening requirements in Sec.           during the last quarter.
 141.135(b)(2) or (3).
                                         (2) The location, date, and
                                          result of each paired sample
                                          and associated alkalinity
                                          taken during the last quarter.
                                         (3) For each month in the
                                          reporting period that paired
                                          samples were taken, the
                                          arithmetic average of the
                                          percent reduction of TOC for
                                          each paired sample and the
                                          required TOC percent removal.
                                         (4) Calculations for
                                          determining compliance with
                                          the TOC percent removal
                                          requirements, as provided in
                                          Sec.  141.135(c)(1).
                                         (5) Whether the system is in
                                          compliance with the enhanced
                                          coagulation or enhanced
                                          softening percent removal
                                          requirements in Sec.
                                          141.135(b) for the last four
                                          quarters.
System monitoring monthly or quarterly   (1) The alternative compliance
 for TOC under the requirements of Sec.   criterion that the system is
  141.132(d) and meeting one or more of   using.
 the alternative compliance criteria in
 Sec.  141.135(a)(2) or (3).
                                         (2) The number of paired
                                          samples taken during the last
                                          quarter.
                                         (3) The location, date, and
                                          result of each paired sample
                                          and associated alkalinity
                                          taken during the last quarter.
                                         (4) The running annual
                                          arithmetic average based on
                                          monthly averages (or quarterly
                                          samples) of source water TOC
                                          for systems meeting a
                                          criterion in Secs.
                                          141.135(a)(2)(i) or (iii) or
                                          of treated water TOC for
                                          systems meeting the criterion
                                          in Sec.  141.135(a)(2)(ii).

[[Page 69473]]

 
                                         (5) The running annual
                                          arithmetic average based on
                                          monthly averages (or quarterly
                                          samples) of source water SUVA
                                          for systems meeting the
                                          criterion in Sec.
                                          141.135(a)(2)(v) or of treated
                                          water SUVA for systems meeting
                                          the criterion in Sec.
                                          141.135(a)(2)(vi).
                                         (6) The running annual average
                                          of source water alkalinity for
                                          systems meeting the criterion
                                          in Sec.  141.135(a)(2)(iii)
                                          and of treated water
                                          alkalinity for systems meeting
                                          the criterion in Sec.
                                          141.135(a)(3)(i).
                                         (7) The running annual average
                                          for both TTHM and HAA5 for
                                          systems meeting the criterion
                                          in Sec.  141.135(a)(2)(iii) or
                                          (iv).
                                         (8) The running annual average
                                          of the amount of magnesium
                                          hardness removal (as CaCO3, in
                                          mg/L) for systems meeting the
                                          criterion in Sec.
                                          141.135(a)(3)(ii).
                                         (9) Whether the system is in
                                          compliance with the particular
                                          alternative compliance
                                          criterion in Sec.
                                          141.135(a)(2) or (3).
------------------------------------------------------------------------
\1\ The State may choose to perform calculations and determine whether
  the treatment technique was met, in lieu of having the system report
  that information.

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

    (a) Applicability. (1) Subpart H systems using conventional 
filtration treatment (as defined in Sec. 141.2 ) must operate with 
enhanced coagulation or enhanced softening to achieve the TOC percent 
removal levels specified in paragraph (b) of this section unless the 
system meets at least one of the alternative compliance criteria listed 
in paragraph (a)(2) or (a)(3) of this section.
    (2) Alternative compliance criteria for enhanced coagulation and 
enhanced softening systems. Subpart H systems using conventional 
filtration treatment may use the alternative compliance criteria in 
paragraphs (a)(2)(i) through (vi) of this section to comply with this 
section in lieu of complying with paragraph (b) of this section. 
Systems must still comply with monitoring requirements in 
Sec. 141.132(d).
    (i) The system's source water TOC level, measured according to 
Sec. 141.131(d)(3), is less than 2.0 mg/L, calculated quarterly as a 
running annual average.
    (ii) The system's treated water TOC level, measured according to 
Sec. 141.131(d)(3), is less than 2.0 mg/L, calculated quarterly as a 
running annual average.
    (iii) The system's source water TOC level, measured as required by 
Sec. 141.131(d)(3), is less than 4.0 mg/L, calculated quarterly as a 
running annual average; the source water alkalinity, measured according 
to Sec. 141.131(d)(1), is greater than 60 mg/L (as CaCO3), 
calculated quarterly as a running annual average; and either the TTHM 
and HAA5 running annual averages are no greater than 0.040 mg/L and 
0.030 mg/L, respectively; or prior to the effective date for compliance 
in Sec. 141.130(b), the system has made a clear and irrevocable 
financial commitment not later than the effective date for compliance 
in Sec. 141.130(b) to use of technologies that will limit the levels of 
TTHMs and HAA5 to no more than 0.040 mg/L and 0.030 mg/L, respectively. 
Systems must submit evidence of a clear and irrevocable financial 
commitment, in addition to a schedule containing milestones and 
periodic progress reports for installation and operation of appropriate 
technologies, to the State for approval not later than the effective 
date for compliance in Sec. 141.130(b). These technologies must be 
installed and operating not later than June 16, 2005. Failure to 
install and operate these technologies by the date in the approved 
schedule will constitute a violation of National Primary Drinking Water 
Regulations.
    (iv) The TTHM and HAA5 running annual averages are no greater than 
0.040 mg/L and 0.030 mg/L, respectively, and the system uses only 
chlorine for primary disinfection and maintenance of a residual in the 
distribution system.
    (v) The system's source water SUVA, prior to any treatment and 
measured monthly according to Sec. 141.131(d)(4), is less than or equal 
to 2.0 L/mg-m, calculated quarterly as a running annual average.
    (vi) The system's finished water SUVA, measured monthly according 
to Sec. 141.131(d)(4), is less than or equal to 2.0 L/mg-m, calculated 
quarterly as a running annual average.
    (3) Additional alternative compliance criteria for softening 
systems. Systems practicing enhanced softening that cannot achieve the 
TOC removals required by paragraph (b)(2) of this section may use the 
alternative compliance criteria in paragraphs (a)(3)(i) and (ii) of 
this section in lieu of complying with paragraph (b) of this section. 
Systems must still comply with monitoring requirements in 
Sec. 141.132(d).
    (i) Softening that results in lowering the treated water alkalinity 
to less than 60 mg/L (as CaCO3), measured monthly according 
to Sec. 141.131(d)(1) and calculated quarterly as a running annual 
average.
    (ii) Softening that results in removing at least 10 mg/L of 
magnesium hardness (as CaCO3), measured monthly and 
calculated quarterly as an annual running average.
    (b) Enhanced coagulation and enhanced softening performance 
requirements. (1) Systems must achieve the percent reduction of TOC 
specified in paragraph (b)(2) of this section between the source water 
and the combined filter effluent, unless the State approves a system's 
request for alternate minimum TOC removal (Step 2) requirements under 
paragraph (b)(3) of this section.
    (2) Required Step 1 TOC reductions, indicated in the following 
table, are based upon specified source water parameters measured in 
accordance with Sec. 141.131(d). Systems practicing softening are 
required to meet the Step 1 TOC reductions in the far-right column 
(Source water alkalinity >120 mg/L) for the specified source water TOC:

[[Page 69474]]



    Step 1 Required Removal of TOC by Enhanced Coagulation and Enhanced Softening for Subpart H Systems Using
                                          Conventional Treatment 1,\\\2
----------------------------------------------------------------------------------------------------------------
                                                                     Source-water alkalinity, mg/L as CaCO3
                                                              --------------------------------------------------
                    Source-water TOC, mg/L                                     60-120     >120 \3\
                                                               0-60 (percent)      (percent)         (percent)
----------------------------------------------------------------------------------------------------------------
>2.0-4.0.....................................................            35.0              25.0             15.0
>4.0-8.0.....................................................            45.0              35.0             25.0
>8.0.........................................................            50.0              40.0            30.0
----------------------------------------------------------------------------------------------------------------
\1\ Systems meeting at least one of the conditions in paragraph (a)(2)(i)-(vi) of this section are not required
  to operate with enhanced coagulation.
\2\ Softening systems meeting one of the alternative compliance criteria in paragraph (a)(3) of this section are
  not required to operate with enhanced softening.
\3\ Systems practicing softening must meet the TOC removal requirements in this column.

    (3) Subpart H conventional treatment systems that cannot achieve 
the Step 1 TOC removals required by paragraph (b)(2) of this section 
due to water quality parameters or operational constraints must apply 
to the State, within three months of failure to achieve the TOC 
removals required by paragraph (b)(2) of this section, for approval of 
alternative minimum TOC (Step 2) removal requirements submitted by the 
system. If the State approves the alternative minimum TOC removal (Step 
2) requirements, the State may make those requirements retroactive for 
the purposes of determining compliance. Until the State approves the 
alternate minimum TOC removal (Step 2) requirements, the system must 
meet the Step 1 TOC removals contained in paragraph (b)(2) of this 
section.
    (4) Alternate minimum TOC removal (Step 2) requirements. 
Applications made to the State by enhanced coagulation systems for 
approval of alternative minimum TOC removal (Step 2) requirements under 
paragraph (b)(3) of this section must include, as a minimum, results of 
bench- or pilot-scale testing conducted under paragraph (b)(4)(i) of 
this section and used to determine the alternate enhanced coagulation 
level.
    (i) Alternate enhanced coagulation level is defined as coagulation 
at a coagulant dose and pH as determined by the method described in 
paragraphs (b)(4)(i) through (v) of this section such that an 
incremental addition of 10 mg/L of alum (as aluminum) (or equivalent 
amount of ferric salt) results in a TOC removal of  0.3 mg/
L. The percent removal of TOC at this point on the ``TOC removal versus 
coagulant dose'' curve is then defined as the minimum TOC removal 
required for the system. Once approved by the State, this minimum 
requirement supersedes the minimum TOC removal required by the table in 
paragraph (b)(2) of this section. This requirement will be effective 
until such time as the State approves a new value based on the results 
of a new bench- and pilot-scale test. Failure to achieve State-set 
alternative minimum TOC removal levels is a violation of National 
Primary Drinking Water Regulations.
    (ii) Bench- or pilot-scale testing of enhanced coagulation must be 
conducted by using representative water samples and adding 10 mg/L 
increments of alum (as aluminum) (or equivalent amounts of ferric salt) 
until the pH is reduced to a level less than or equal to the enhanced 
coagulation Step 2 target pH shown in the following table:

                  Enhanced Coagulation Step 2 target pH
------------------------------------------------------------------------
                 Alkalinity (mg/L as CaCO3)                   Target pH
------------------------------------------------------------------------
0-60.......................................................          5.5
>60-120....................................................          6.3
>120-240...................................................          7.0
>240.......................................................          7.5
------------------------------------------------------------------------

    (iii) For waters with alkalinities of less than 60 mg/L for which 
addition of small amounts of alum or equivalent addition of iron 
coagulant drives the pH below 5.5 before significant TOC removal 
occurs, the system must add necessary chemicals to maintain the pH 
between 5.3 and 5.7 in samples until the TOC removal of 0.3 mg/L per 10 
mg/L alum added (as aluminum) (or equivalant addition of iron 
coagulant) is reached.
    (iv) The system may operate at any coagulant dose or pH necessary 
(consistent with other NPDWRs) to achieve the minimum TOC percent 
removal approved under paragraph (b)(3) of this section.
    (v) If the TOC removal is consistently less than 0.3 mg/L of TOC 
per 10 mg/L of incremental alum dose (as aluminum) at all dosages of 
alum (or equivalant addition of iron coagulant), the water is deemed to 
contain TOC not amenable to enhanced coagulation. The system may then 
apply to the State for a waiver of enhanced coagulation requirements.
    (c) Compliance calculations. (1) Subpart H systems other than those 
identified in paragraph (a)(2) or (a)(3) of this section must comply 
with requirements contained in paragraph (b)(2) of this section. 
Systems must calculate compliance quarterly, beginning after the system 
has collected 12 months of data, by determining an annual average using 
the following method:
    (i) Determine actual monthly TOC percent removal, equal to:

(1--(treated water TOC/source water TOC))  x  100

    (ii) Determine the required monthly TOC percent removal (from 
either the table in paragraph (b)(2) of this section or from paragraph 
(b)(3) of this section).
    (iii) Divide the value in paragraph (c)(1)(i) of this section by 
the value in paragraph (c)(1)(ii) of this section.
    (iv) Add together the results of paragraph (c)(1)(iii) of this 
section for the last 12 months and divide by 12.
    (v) If the value calculated in paragraph (c)(1)(iv) of this section 
is less than 1.00, the system is not in compliance with the TOC percent 
removal requirements.
    (2) Systems may use the provisions in paragraphs (c)(2)(i) through 
(v) of this section in lieu of the calculations in paragraph (c)(1)(i) 
through (v) of this section to determine compliance with TOC percent 
removal requirements.
    (i) In any month that the system's treated or source water TOC 
level, measured according to Sec. 141.131(d)(3), is less than 2.0 mg/L, 
the system may assign a monthly value of 1.0 (in lieu of the value 
calculated in paragraph (c)(1)(iii) of this section) when calculating 
compliance under the provisions of paragraph (c)(1) of this section.
    (ii) In any month that a system practicing softening removes at 
least 10 mg/L of magnesium hardness (as CaCO3), the system 
may assign a

[[Page 69475]]

monthly value of 1.0 (in lieu of the value calculated in paragraph 
(c)(1)(iii) of this section) when calculating compliance under the 
provisions of paragraph (c)(1) of this section.
    (iii) In any month that the system's source water SUVA, prior to 
any treatment and measured according to Sec. 141.131(d)(4), is 
2.0 L/mg-m, the system may assign a monthly value of 1.0 (in 
lieu of the value calculated in paragraph (c)(1)(iii) of this section) 
when calculating compliance under the provisions of paragraph (c)(1) of 
this section.
    (iv) In any month that the system's finished water SUVA, measured 
according to Sec. 141.131(d)(4), is 2.0 L/mg-m, the system 
may assign a monthly value of 1.0 (in lieu of the value calculated in 
paragraph (c)(1)(iii) of this section) when calculating compliance 
under the provisions of paragraph (c)(1) of this section.
    (v) In any month that a system practicing enhanced softening lowers 
alkalinity below 60 mg/L (as CaCO3), the system may assign a 
monthly value of 1.0 (in lieu of the value calculated in paragraph 
(c)(1)(iii) of this section) when calculating compliance under the 
provisions of paragraph (c)(1) of this section.
    (3) Subpart H systems using conventional treatment may also comply 
with the requirements of this section by meeting the criteria in 
paragraph (a)(2) or (3) of this section.
    (d) Treatment technique requirements for DBP precursors. The 
Administrator identifies the following as treatment techniques to 
control the level of disinfection byproduct precursors in drinking 
water treatment and distribution systems: For Subpart H systems using 
conventional treatment, enhanced coagulation or enhanced softening.
    11. Section 141.154 is amended by adding paragraph (e) to read as 
follows:


Sec. 141.154  Required additional health information.

* * * * *
    (e) Community water systems that detect TTHM above 0.080 mg/l, but 
below the MCL in Sec. 141.12, as an annual average, monitored and 
calculated under the provisions of Sec. 141.30, must include health 
effects language prescribed by paragraph (73) of appendix C to subpart 
O.

PART 142--NATIONAL PRIMARY DRINKING WATER REGULATIONS 
IMPLEMENTATION

    12. 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.

    13. Section 142.14 is amended by adding new paragraphs (d)(12), 
(d)(13), (d)(14), (d)(15), and (d)(16) to read as follows.


Sec. 142.14  Records kept by States.

* * * * *
    (d) * * *
    (12) Records of the currently applicable or most recent State 
determinations, including all supporting information and an explanation 
of the technical basis for each decision, made under the following 
provisions of 40 CFR part 141, subpart L for the control of 
disinfectants and disinfection byproducts. These records must also 
include interim measures toward installation.
    (i) States must keep records of systems that are installing GAC or 
membrane technology in accordance with Sec. 141.64(b)(2) of this 
chapter. These records must include the date by which the system is 
required to have completed installation.
    (ii) States must keep records of systems that are required, by the 
State, to meet alternative minimum TOC removal requirements or for whom 
the State has determined that the source water is not amenable to 
enhanced coagulation in accordance with Sec. 141.135(b)(3) and (4) of 
this chapter, respectively. These records must include the alternative 
limits and rationale for establishing the alternative limits.
    (iii) States must keep records of subpart H systems using 
conventional treatment meeting any of the alternative compliance 
criteria in Sec. 141.135(a)(2) or (3) of this chapter.
    (iv) States must keep a register of qualified operators that have 
met the State requirements developed under Sec. 142.16(f)(2).
    (13) Records of systems with multiple wells considered to be one 
treatment plant in accordance with Sec. 141.132(a)(2) of this chapter 
and Sec. 142.16(f)(5).
    (14) Monitoring plans for subpart H systems serving more than 3,300 
persons in accordance with Sec. 141.132(f) of this chapter.
    (15) List of laboratories approved for analyses in accordance with 
Sec. 141.131(b) of this chapter.
    (16) List of systems required to monitor for disinfectants and 
disinfection byproducts in accordance with part 141, subpart L of this 
chapter. The list must indicate what disinfectants and DBPs, other than 
chlorine, TTHM, and HAA5, if any, are measured.
* * * * *
    14. Section 142.16 is amended by adding paragraph (h) to read as 
follows.


Sec. 142.16  Special primacy requirements.

* * * * *
    (h) Requirements for States to adopt 40 CFR part 141, subpart L. In 
addition to the general primacy requirements elsewhere in this part, 
including the requirement that State regulations be at least as 
stringent as federal requirements, an application for approval of a 
State program revision that adopts 40 CFR part 141, subpart L, must 
contain a description of how the State will accomplish the following 
program requirements:
    (1) Section 141.64(b)(2) of this chapter (interim treatment 
requirements). Determine any interim treatment requirements for those 
systems electing to install GAC or membrane filtration and granted 
additional time to comply with Sec. 141.64 of this chapter.
    (2) Section 141.130(c) of this chapter (qualification of 
operators). Qualify operators of public water systems subject to 40 CFR 
part 141, subpart L. Qualification requirements established for 
operators of systems subject to 40 CFR part 141, subpart H--Filtration 
and Disinfection may be used in whole or in part to establish operator 
qualification requirements for meeting 40 CFR part 141, subpart L 
requirements if the State determines that the 40 CFR part 141, subpart 
H requirements are appropriate and applicable for meeting subpart L 
requirements.
    (3) Section 141.131(c)(2) of this chapter (DPD colorimetric test 
kits). Approve DPD colorimetric test kits for free and total chlorine 
measurements. State approval granted under Sec. 141.74(a)(2) of this 
chapter for the use of DPD colorimetric test kits for free chlorine 
testing is acceptable for the use of DPD test kits in measuring free 
chlorine residuals as required in 40 CFR part 141, subpart L.
    (4) Sections 141.131(c)(3) and (d) of this chapter (State approval 
of parties to conduct analyses). Approve parties to conduct pH, 
bromide, alkalinity, and residual disinfectant concentration 
measurements. The State's process for approving parties performing 
water quality measurements for systems subject to 40 CFR part 141, 
subpart H requirements in paragraph (b)(2)(i)(D) of this section may be 
used for approving parties measuring water quality parameters for 
systems subject to subpart L requirements, if the State determines the 
process is appropriate and applicable.

[[Page 69476]]

    (5) Section 141.132(a)(2) of this chapter (multiple wells as a 
single source). Define the criteria to use to determine if multiple 
wells are being drawn from a single aquifer and therefore be considered 
a single source for compliance with monitoring requirements.
    (6) Approve alternate minimum TOC removal (Step 2) requirements, as 
allowed under the provisions of Sec. 141.135(b) of this chapter.

[FR Doc. 98-32887 Filed 12-15-98; 8:45 am]
BILLING CODE 6560-50-U