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National Primary Drinking Water Regulations:
Interim Enhanced Surface Water Treatment
Federal Register Document
Related Material
[Federal Register: December 16, 1998 (Volume 63, Number 241)]
[Rules and Regulations]
[Page 69477-69521]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr16de98-18]
[[Page 69477]]
_______________________________________________________________________
Part V
Environmental Protection Agency
_______________________________________________________________________
40 CFR Parts 9, 141, and 142
National Primary Drinking Water Regulations: Interim Enhanced Surface
Water Treatment; Final Rule
[[Page 69478]]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 9, 141, and 142
[WH-FRL-6199-9]
RIN 2040-AC91
National Primary Drinking Water Regulations: Interim Enhanced
Surface Water Treatment
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: In this document, EPA is finalizing the Interim Enhanced
Surface Water Treatment Rule (IESWTR). The purposes of the IESWTR are
to: Improve control of microbial pathogens, including specifically the
protozoan Cryptosporidium, in drinking water; and address risk trade-
offs with disinfection byproducts. Key provisions established in
today's final IESWTR include: A Maximum Contaminant Level Goal (MCLG)
of zero for Cryptosporidium; 2-log Cryptosporidium removal requirements
for systems that filter; strengthened combined filter effluent
turbidity performance standards and individual filter turbidity
provisions; disinfection benchmark provisions to assure continued
levels of microbial protection while facilities take the necessary
steps to comply with new disinfection byproduct standards; inclusion of
Cryptosporidium in the definition of ground water under the direct
influence of surface water (GWUDI) and in the watershed control
requirements for unfiltered public water systems; requirements for
covers on new finished water reservoirs; and sanitary surveys for all
surface water systems regardless of size. The IESWTR builds upon the
treatment technique requirements of the Surface Water Treatment Rule.
EPA believes that implementation of the IESWTR will significantly
reduce the level of Cryptosporidium in finished drinking water supplies
through improvements in filtration. The Agency estimates that the
likelihood of endemic illness from Cryptosporidium will decrease by
110,000 to 463,000 cases annually. The Agency believes that the rule
will also reduce the likelihood of the occurrence of outbreaks of
cryptosporidiosis by providing a larger margin of safety against such
outbreaks for some systems. In addition, the filtration provisions of
the rule are expected to increase the level of protection from exposure
to other pathogens (i.e., Giardia or other waterborne bacterial or
viral pathogens).
The IESWTR applies to public water systems that use surface water
or GWUDI and serve 10,000 or more people. The rule also requires
primacy States to conduct sanitary surveys for all surface water and
GWUDI systems regardless of size.
EFFECTIVE DATE: This regulation is effective February 16, 1999.
Compliance dates for specific components of the rule are discussed in
the Supplementary Information section.
ADDRESSES: Public comments, the comment/response document, applicable
Federal Register notices, 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., Rm. EB57,
Washington, DC 20460 from 9 a.m. to 4 p.m., Monday through Friday,
excluding legal holidays. For access to docket materials, please call
(202) 260-3027 to schedule an appointment.
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 a.m. to 5:30 p.m. Eastern Time. For technical
inquiries, contact Elizabeth Corr or Paul S. Berger, Ph.D.
(Microbiology), Office of Ground Water and Drinking Water (MC 4607),
U.S. Environmental Protection Agency, 401 M Street SW, Washington DC
20460; telephone (202) 260-8907 (Corr) or (202) 260-3039 (Berger). For
Regional contacts see Supplementary Information.
SUPPLEMENTARY INFORMATION: This regulation is effective 60 days after
publication of FR 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 potentially regulated by the IESWTR
are public water systems that use surface water or ground water under
the direct influence of surface water and serve at least 10,000 people.
(States are required to carry out sanitary surveys for all surface
water and GWUDI systems including those that serve less than 10,000
people.) Regulated categories and entities include:
------------------------------------------------------------------------
Category Examples of regulated entities
------------------------------------------------------------------------
Industry..................... Public Water Systems (PWSs) that use
surface water or ground water under the
direct influence of surface water and
serve at least 10,000 people
State, Local, Tribal or PWSs that use surface water or ground
Federal Governments. water under the direct influence of
surface water and serve at least 10,000
people.
------------------------------------------------------------------------
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by the
IESWTR. This table lists the types of entities that EPA is now aware
could potentially be regulated by the rule. 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 subpart H (Sec. 141.70(a)--systems subject to
the Surface Water Treatment Rule) and subpart P (Sec. 141.170(a)--
subpart H systems that serve 10,000 or more people) of the final rule.
If you have questions regarding the applicability of the IESWTR to a
particular entity, consult one of the persons listed in the preceding
FOR FURTHER INFORMATION CONTACT section.
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
IV. David Parker, Water Supply Section, 345 Courtland Street, Atlanta,
GA 30365, (404) 562-9460
V. Kimberly Harris, Water Supply Section, 77 W. Jackson Blvd., Chicago,
IL 60604, (312) 886-4239
[[Page 69479]]
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
List of Abbreviations Used in This Document
ASCE: American Society of Civil Engineers
ASDWA: Association of State Drinking Water Administrators
ASTM: American Society for Testing and Materials
AWWA: American Water Works Association
AWWARF: American Water Works Association Research Foundation
deg.C: Degrees Centigrade
CCP: Composite Correction Program
CDC: Centers for Disease Control
CFE: Combined Filter Effluent
CFR: Code of Federal Regulations
CPE: Comprehensive Performance Evaluation
CT: The Residual Concentration of Disinfectant (mg/L) Multiplied by the
Contact Time (in minutes)
CTA: Comprehensive Technical Assistance
DBPs: Disinfection Byproducts
DBPR: Disinfectants/Disinfection Byproducts Rule
ESWTR: Enhanced Surface Water Treatment Rule
FACA: Federal Advisory Committee Act
GAC: Granular Activated Carbon
GAO: Government Accounting Office
GWUDI: Ground Water Under the Direct Influence of Surface Water
HAA5: Haloacetic acids (Monochloroacetic, Dichloroacetic,
Trichloroacetic, Monobromoacetic and Dibromoacetic Acids)
HPC: Heterotropic Plate Count
hrs: Hours
ICR: Information Collection Rule
IESWTR: Interim Enhanced Surface Water Treatment Rule
IFA: Individual Filter Assessment
Log Inactivation: Logarithm of (N<INF>0</INF>/N<INF>T</INF>)
Log: Logarithm (common, base 10)
LTESWTR: Long Term Enhanced Surface Water Treatment Rule
LT1: Long Term 1 Enhanced Surface Water Treatment Rule
MCL: Maximum Contaminant Level
MCLG: Maximum Contaminant Level Goal
M-DBP: Microbial and Disinfectants/Disinfection Byproducts
MPA: Microscopic Particulate Analysis
NODA: Notice of Data Availability
NPDWR: National Primary Drinking Water Regulation
N<INF>T</INF>: The Concentration of Surviving Microorganisms at Time T
NTTAA: National Technology Transfer and Advancement Act
NTU: Nephelometric Turbidity Unit
PE: Performance Evaluation
PWS: Public Water System
Reg. Neg.: Regulatory Negotiation
RIA: Regulatory Impact Analysis
RFA: Regulatory Flexibility Act
RSD: Relative Standard Deviation
SAB: Science Advisory Board
SDWA: Safe Drinking Water Act
SWTR: Surface Water Treatment Rule
TC: Total Coliforms
TCR: Total Coliform Rule
TTHM: Total Trihalomethanes
TWG: Technical Work Group
UMRA: Unfunded Mandates Reform Act
x log removal: Reduction to \1/10\<SUP>x </SUP>of original
concentration
Table of Contents
I. Background
A. Statutory Requirements and Legal Authority
B. Regulatory History
1. Existing Regulations
--Surface Water Treatment Rule (SWTR)
--Total Coliform Rule (TCR)
--Total Trihalomethane (TTHM) Rule
--Information Collection Rule (ICR)
2. Public Health Concerns to be Addressed
3. Regulatory Negotiation Process
4. Federal Advisory Committee Process
5. Overview of 1994 Proposal and 1997 Notice of Data
Availability
II. Summary of the Final Rule
III. Explanation of Today's Action
A. MCLG for Cryptosporidium
1. Today's Rule
2. Background and Analysis
3. Summary of Major Comments
B. Removal of Cryptosporidium by Filtration
1. Today's Rule
2. Background and Analysis
3. Summary of Major Comments
C. Turbidity Control
1. Today's Rule
2. Background and Analysis
3. Summary of Major Comments
D. Disinfection Benchmark for Stage 1 DBPR MCLs
1. Today's Rule
2. Background and Analysis
3. Summary of Major Comments
E. Definition of Ground Water Under the Direct Influence of Surface
Water
1. Today's Rule
2. Background and Analysis
3. Summary of Major Comments
F. Inclusion of Cryptosporidium in Watershed Control Requirements
1. Today's Rule
2. Background and Analysis
3. Summary of Major Comments
G. Covered Finished Water Reservoirs
1. Today's Rule
2. Background and Analysis
3. Summary of Major Comments
H. Sanitary Survey Requirements
1. Today's Rule
2. Background and Analysis
3. Summary of Major Comments
I. Compliance Schedules
1. Today's Rule
2. Background and Analysis
3. Summary of Major Comments
IV. State Implementation
A. Special State Primacy Requirements
B. State Recordkeeping Requirements
C. State Reporting Requirements
D. Interim Primacy
V. Economic Analysis
A. Today's Rule
B. Overview of RIA for Proposed Rule
C. What's Changed Since the Proposed Rule
D. Summary of Cost Analysis
E. Household Costs
F. Summary of Benefits Analysis
G. Comparison of Costs and Benefits
VI. Additional Issues Discussed in 1994 Proposal and 1997 NODA
A. Inactivation of Cryptosporidium
B. Giardia Inactivation CT values for Profiling/Benchmarking
C. Cross Connection Control
D. Filter Backwash Recycling
E. Certification Criteria for Water Plant Operators
VII. Other Requirements
A. Regulatory Flexibility Act
B. Paperwork Reduction Act
C. Unfunded Mandates Reform Act
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. Executive Order 12875: Enhancing the Intergovernmental
Partnership
I. Executive Order 13084: Consultation and Coordination With Indian
Tribal Governments
J. Consultation with the Science Advisory Board, National Drinking
Water Council, and Secretary of Health and Human Services
K. Likely Effect of Compliance with the IESWTR on the Technical,
Financial, and Managerial Capacity of Public Water Systems
L. Submission to Congress and the General Accounting Office
VIII. References
I. Background
A. Statutory Requirements and Legal Authority
The Safe Drinking Water Act (SDWA or the Act), as amended in 1986,
[[Page 69480]]
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(l) 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''
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 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))
and to promulgate regulations specifying criteria for requiring
disinfection ``as necessary'' for ground water systems.
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 (SWTR)
Under the Surface Water Treatment Rule (SWTR) (54 FR 27486, June
29, 1989) (EPA, 1989b), EPA set maximum contaminant level goals of zero
for Giardia lamblia, viruses, and Legionella; and promulgated National
Primary Drinking Water Regulations 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 maintenance of a disinfectant residual in
the distribution system; (2) removal and/or inactivation of 3 log
(99.9%) for Giardia and 4 log (99.99%) for viruses; (3) combined filter
effluent turbidity performance standard of 5 NTU as a maximum and 0.5
NTU at the 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 (TCR)
The Total Coliform Rule (TCR) (54 FR 27544, June 29, 1989) applies
to all public water systems (EPA, 1989c). This regulation sets
compliance with the Maximum Contaminant Level (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 if necessary) within 24 hours of being notified of a TC-
positive sample.
The TCR also requires an on-site inspection (referred to as a
sanitary survey) every 5 years for each system that collects fewer than
five samples per month. (This requirement is extended to every10 years
for non-community systems using only protected and disinfected ground
water.)
Total Trihalomethane (TTHM) Rule
In November 1979 (44 FR 68624) (EPA, 1979) EPA set an interim MCL
for total trihalomethanes (TTHM) of 0.10 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,
dibromochloromethane 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 (ICR)
The Information Collection Rule (ICR) is a monitoring and data
reporting rule that was promulgated on May 14, 1996 (61 FR 24354) (EPA,
1996b). The purpose of the ICR is to collect occurrence and treatment
information to
[[Page 69481]]
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
(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 (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
of 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 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 plant 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 Interim Enhanced
Surface Water Treatment Rule (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
In 1990, EPA's Science Advisory Board (SAB), an independent panel
of experts established by Congress, cited drinking water contamination
as one of the most important environmental risks and indicated that
disease-causing microbial contaminants (i.e., bacteria, protozoa and
viruses) are probably the greatest remaining health risk management
challenge for drinking water suppliers (EPA/SAB, 1990). Information on
the number of waterborne disease outbreaks from the U.S. Centers for
Disease Control and Prevention (CDC) underscores this concern. CDC
indicates that, between 1980 and 1996, 401 waterborne disease outbreaks
were reported, with over 750,000 associated cases of disease (Craun
1998, 1997a; Kramer et al 1996). During this period, a number of agents
were implicated as the cause, including protozoa, viruses and bacteria,
as well as several chemicals. Most of the cases (but not outbreaks)
were associated with surface water, and specifically with a single
outbreak of cryptosporidiosis in Milwaukee (over 400,000 cases)
(MacKenzie et al, 1994).
It is important to note that for a number of reasons, the CDC
reports may substantially understate the actual number of waterborne
disease outbreaks and cases in the U.S. First, few States have an
active outbreak surveillance program. Second, disease outbreaks are
often not recognized in a community or, if recognized, are not traced
to the drinking water source. Third, a large number of people
experiencing gastrointestinal illness (predominantly diarrhea) do not
seek medical attention. Fourth, physicians may often not have a broad
enough community-wide basis of information to attribute
gastrointestinal illness to any specific origin such as a drinking
water source. Finally, an unknown but probably significant portion of
waterborne disease is endemic (i.e., not associated with an outbreak),
and thus is even more difficult to recognize.
Waterborne disease is usually acute (i.e., sudden onset and
typically lasting a short time in healthy people). Some pathogens
(e.g., Giardia, Cryptosporidium) may cause extended illness, sometimes
lasting months or longer, in otherwise healthy individuals. Most
waterborne pathogens cause gastrointestinal illness, with diarrhea,
abdominal discomfort, nausea, vomiting, and/or other symptoms. Other
waterborne pathogens cause, or at least are associated with, more
serious disorders such as hepatitis, gastric cancer, peptic ulcers,
myocarditis, swollen lymph glands, meningitis, encephalitis, and a
myriad of other diseases.
Gastrointestinal illness may be chronic in vulnerable populations
(e.g., immunocompromised individuals). The severity and duration of
illness is often greater in immunocompromised persons than in healthy
individuals and may be fatal among this population. For instance, a
follow-up study of the 1993 Milwaukee waterborne disease outbreak
reported that at least 50 Cryptosporidium-associated deaths occurred
among the severely immunocompromised (Hoxie et al., 1997).
Immunocompromised persons include infants, pregnant women, the elderly,
and especially those with severely weakened immune systems (e.g., AIDS
patients, those receiving treatment for certain types of cancer, organ-
transplant recipients and people on immunosuppressant drugs) (Gerba et
al., 1996).
With specific reference to cryptosporidiosis, the disease is caused
by ingestion of environmentally-resistant Cryptosporidium oocysts,
which are readily carried by the waterborne route. Humans and other
animals may excrete these oocysts. Transmission of this disease often
occurs through ingestion of the infective oocysts from contaminated
water or food, but may also result from direct or indirect contact with
infected persons or animals (Casemore, 1990; Cordell and Addiss, 1994).
Symptoms of cryptosporidiosis include typical gastrointestinal symptoms
(Current et al., 1983). As noted above, these may persist for several
days to several months.
While cryptosporidiosis is generally a self-limiting disease with a
complete
[[Page 69482]]
recovery in otherwise healthy persons, it can be very serious in
immunosuppressed persons. EPA has a particular concern regarding
drinking water exposure to Cryptosporidium, especially in severely
immunocompromised persons, because there is no effective therapeutic
drug to cure the disease. There have been a number of waterborne
disease outbreaks caused by Cryptosporidium in the United States,
United Kingdom and many other countries (Rose, 1997). There appears to
be an immune response to Cryptosporidium, but it is not known if this
results in protection (Fayer and Ungar, 1986).
One of the key regulations EPA has developed and implemented to
counter pathogens in drinking water is the SWTR. Among its provisions,
the rule requires that a surface water system have sufficient treatment
to reduce the source water concentration of Giardia and viruses by at
least 99.9% (3 log) and 99.99% (4 log), respectively. A shortcoming of
the SWTR is that the rule does not specifically control for the
protozoan Cryptosporidium. The first report of a recognized outbreak
caused by Cryptosporidium was published during the development of the
SWTR (D'Antonio et al., 1985).
In terms of occurrence, Cryptosporidium is common in the
environment. Runoff from unprotected watersheds allows transport of
these microorganisms to water bodies used as intake sites for drinking
water treatment plants. A particular public health challenge is that
simply increasing existing disinfection levels above those most
commonly practiced in the United States today does not appear to be an
effective strategy for controlling Cryptosporidium, because the
Cryptosporidium oocyst is especially resistant to disinfection
practices commonly used at water treatment plants. Today's rule
addresses the concern of passage of Cryptosporidium through physical
removal processes during water treatment. It also strengthens the
effectiveness and reliability of physical removal for particulate
matter and microorganisms in general, thereby reducing the likelihood
of the disinfection barrier being over challenged. Waterborne disease
outbreaks have been associated with a high level of particles passing
through a water treatment plant (Fox and Lytle, 1996). This presents a
significant public health concern. Hence, there is a need to optimize
treatment reliability and to enhance physical removal efficiencies to
minimize the Cryptosporidium levels in finished water. This rule, with
tightened turbidity performance criteria and required individual filter
monitoring, is formulated to address these public health concerns.
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 ``long-term'' ESWTR, and an Information
Collection Rule (proposal: 59 FR 6332, February 10, 1994) (EPA, 1994c)
(promulgation: 61FR24354, May 14, 1996) (EPA, 1996b). The approach used
in developing these proposals considered the constraints of
simultaneously treating water to control for both microbial
contaminants and disinfectants/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 from both pathogens and disinfectants/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 Microbial-
Disinfectants/Disinfection Byproducts (M-DBP) Advisory Committee under
the Federal Advisory Committee Act (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
[[Page 69483]]
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 issues addressed by the Committee and in the NODAs
include: (1) Maintain the proposed MCLs for TTHMs, 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) 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. The Committee's recommendations are embodied in an
Agreement In Principle document dated July 15, 1997.
5. Overview of 1994 Proposal and 1997 Notice of Data Availability
EPA proposed to amend the Surface Water Treatment Rule in 1994 to
provide additional protection against disease-causing organisms
(pathogens) in drinking water (59 FR 38832: July 29, 1994). In November
1997 EPA published a Notice of Data Availability (62 FR 59486) (EPA,
1997a, b) that summarized the 1994 proposal; described new data and
information that the Agency had obtained and analyses that had been
developed since the proposal; provided information concerning the July
1997 recommendations of the M-DBP Advisory Committee described above on
key issues related to the proposal; and requested comment on these
recommendations as well as on other regulatory implications that flowed
from the new data and information. The Agency also solicited additional
data and information that were relevant to the issues discussed in the
Notice. In addition, EPA provided notice that the Agency was re-opening
the comment period for the 1994 proposal for 90 days. EPA also
requested that any information that members of the public would like
the Agency to 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
reopened 90-day comment period unless already in the underlying record
in the Docket for the Notice of Data Availability.
II. Summary of the Final Rule
The primary purposes of the IESWTR are (1) to improve control of
microbial pathogens in drinking water, particularly for the protozoan
Cryptosporidium, and (2) to guard against significant increases in
microbial risk that might otherwise occur when systems implement the
Stage 1 Disinfectants/Disinfection Byproducts Rule. Major components of
the IESWTR include the following provisions:
(a) A Maximum Contaminant Level Goal (MCLG) of zero is established
for the protozoan genus Cryptosporidium.
(b) Surface water systems serving 10,000 or more people, that are
required to filter under the SWTR, must achieve at least 2 log removal
of Cryptosporidium. Systems that use conventional or direct filtration
meet this requirement if they comply with strengthened turbidity
performance standards for combined filter effluent (described below)
and the current requirements under the SWTR (e.g., meet design and
operating conditions as specified by the State). Systems that use slow
sand filtration or diatomaceous earth meet the 2 log removal
requirement if they are in compliance with existing turbidity
performance standards under the SWTR (less than or equal to 1 NTU in at
least 95% of measurements taken each month or, for slow sand,
alternative criteria as approved by the State; and a maximum of 5 NTU).
(c) The rule includes a series of requirements related to
turbidity. These address the following:
Strengthened turbidity performance requirements for the combined
filter effluent. For all surface water or GWUDI systems that use
conventional treatment or direct filtration, serve 10,000 or more
people, and are required to filter: (a) The turbidity level of a
system's combined filtered water at each plant must be less than or
equal to 0.3 NTU in at least 95 percent of the measurements taken each
month, and (b) the turbidity level of a system's combined filtered
water at each plant must at no time exceed 1 NTU. For both the maximum
and the 95th percentile requirements, compliance is determined based on
measurements of the combined filter effluent at four-hour intervals.
Individual Filter Requirements. All surface water or GWUDI systems
that use conventional or direct filtration, serve 10,000 or more
people, and are required to filter must conduct continuous monitoring
of turbidity for each individual filter and must provide an exceptions
report to the State on a monthly basis. Exceptions reporting must
include the following: (1) Any individual filter with a turbidity level
greater than 1.0 NTU based on two consecutive measurements fifteen
minutes apart; and (2) any individual filter with a turbidity level
greater than 0.5 NTU at the end of the first 4 hours of filter
operation based on two consecutive measurements fifteen minutes apart.
A filter profile (which is a graphical representation of an individual
filter performance) must be produced within seven days of the
exceedance if no obvious reason for the abnormal filter performance can
be identified.
If an individual filter has turbidity levels greater than 1.0 NTU
based on two consecutive measurements fifteen minutes apart at any time
in each of three consecutive months, the system must make an exceptions
report and conduct a self-assessment of the filter. If an individual
filter has turbidity levels greater than 2.0 NTU based on two
consecutive measurements fifteen minutes apart at any time in each of
two consecutive months, the system must make an exception report and
arrange for the conduct of a Comprehensive Performance Evaluation (CPE)
by the State or a third party approved by the State.
State Authority. States must have rules or other authority to
require systems to conduct a Composite Correction Program (CCP) and to
assure that systems implement any follow-up recommendations that result
as part of the CCP. The CCP consists of two elements--a CPE and
Comprehensive Technical Assistance (CTA). The CPE is a thorough review
and analysis of a plant's performance-based capabilities and associated
administrative, operation and maintenance practices. It is conducted to
identify factors that may
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be adversely impacting a plant's capability to achieve compliance and
emphasizes approaches that can be implemented without significant
capital improvements. The CPE must include the following components:
(1) Assessment of plant performance; (2) evaluation of major unit
processes; (3) identification and prioritization of performance
limiting factors; (4) assessment of the applicability of comprehensive
technical assistance; and (5) preparation of a CPE report. A CTA is the
performance improvement phase that is implemented if the CPE results
indicate improved performance potential. During the CTA phase, the
system must identify and systematically address plant-specific factors.
The CTA is a combination of utilizing CPE results as a basis for follow
up, implementing process control priority-setting techniques, and
maintaining long-term involvement to systematically train staff and
administrators.
(d) Microbial benchmarking/profiling requirements are included to
provide a methodology and process by which a public water system and
the State, working together, assure that there will be no significant
reduction in microbial protection as the result of significant
disinfection practice modifications in order to meet MCLs for TTHM and
HAA5. The disinfection profiling requirement included in today's rule
applies to surface water systems serving 10,000 or more people and
which have, based on a one year running annual average of
representative samples taken in the distribution system, (1) measured
TTHM levels of at least 80% of the MCL (0.064 mg/L) or (2) measured
HAA5 levels of at least 80% of the MCL (0.048 mg/L). Those PWSs
required to develop a disinfection profile that subsequently decide to
make a significant change in disinfection practice must consult with
the State prior to implementing such a change.
(e) States are required to conduct sanitary surveys for all public
water systems using surface water or ground water under the direct
influence of surface water, regardless of system size. Sanitary surveys
are required no less frequently than every three years for community
systems and no less frequently than every five years for noncommunity
systems. For community systems determined by the State to have
outstanding performance based on prior sanitary surveys, subsequent
sanitary surveys may be conducted no less frequently than every five
years. States must have the appropriate rules or other authority to
require systems to respond in writing to significant deficiencies
outlined in a sanitary survey report within at least 45 days,
indicating how and on what schedule the system will address significant
deficiencies noted in the survey. States must also have the appropriate
rules or other authority to assure that facilities take the steps
necessary to address significant deficiencies identified in the survey
report that are within the control of the PWS and its governing body.
(f) Cryptosporidium is added to the definition of ground water
under the direct influence of surface water (for systems serving 10,000
or more people).
(g) Cryptosporidium is added to the watershed protection
requirements for systems that are avoiding filtration (for systems
serving 10,000 or more people).
(h) Surface Water and GWUDI systems serving 10,000 or more people
are required to cover all new treated water reservoirs, holding tanks
or other storage facilities for which construction begins after the
effective date of the rule.
The Surface Water Treatment Rule remains the base rule regulating
public water systems that use surface water and ground water under the
influence of surface water. All systems, filtered and unfiltered, must
continue to comply with all the requirements of the SWTR and, where
applicable, meet the new requirements of the IESWTR. The IESWTR's
requirements for filtered systems are intended to ensure that where a
filtration plant is required to protect public health, as specified in
the SWTR, that plant will be operating well for the removal of
Cryptosporidium and other microorganisms. EPA wishes to emphasize that
compliance with today's requirements in no way relieves a public water
system of its obligation to comply fully with pre-existing SWTR
requirements. With regard to unfiltered systems in particular,
development of today's rule was based on the assumption of full
compliance with all filtration avoidance criteria in the SWTR.
Finally, EPA notes that today's Federal Register also contains the
final Stage 1 Disinfectants/Disinfection Byproducts Rule (DBPR). EPA
proposed this rule at the same time as the IESWTR and has finalized it
along with the IESWTR.
III. Explanation of Today's Action
A. MCLG for Cryptosporidium
1. Today's Rule
The Agency is establishing an MCLG of zero for Cryptosporidium, as
proposed. During the 1997 M-DBP Advisory Committee discussions, the
Committee supported the proposed establishment of an MCLG of zero for
Cryptosporidium. A key issue identified by the Advisory Committee and
public commenters was whether the MCLG should be set at the genus level
(i.e., Cryptosporidium) or at the more specific species level (i.e., C.
parvum). Because of the uncertainties regarding taxonomy, cross
reactions and cross transmission among mammals, EPA believes it is
premature to establish the Cryptosporidium MCLG at the species level.
In addition, the Agency believes that establishing an MCLG for
Cryptosporidium at the genus level is consistent with the Safe Drinking
Water Act, which requires EPA to set the MCLG with an adequate margin
of safety (Section 1412(b)(4)(A)).
2. Background and Analysis
In the 1994 proposal of the IESWTR (59 FR 145, p. 38855; July 29,
1994), EPA proposed to establish an MCLG of zero for Cryptosporidium.
The Agency based its proposal upon concerns about significant health
effects on persons consuming inadequately treated surface waters and
ground water under the influence of surface waters. Technical
justifications for the proposed MCLG relied upon animal studies and
human epidemiology studies of waterborne outbreaks of
cryptosporidiosis.
Since the proposed rule, results of a human feeding study have
become available which further warrant the establishment of an MCLG of
zero (1997 NODA 59492). DuPont et al. (1995) fed 29 healthy volunteers
single doses ranging from 30 to 1 million C. parvum oocysts obtained
from a calf. Of the 16 volunteers who received 300 or more oocysts, 88%
became infected. Of the five volunteers who received the lowest dose
(30 oocysts), one became infected. According to a mathematical model
based upon the DuPont et al. data, if an individual ingests a single
viable oocyst there is about a 0.5% chance of infection (Haas et al.,
1996). The probability of infection from C. parvum may be different for
different strains.
In the process of further reviewing new information since 1994, EPA
has re-examined the issues related to setting an MCLG at the genus
level versus the species level. This issue was discussed in some detail
during the M-DBP Advisory Committee meetings. Currently, the
classification of a number of Cryptosporidium species is based, in
part, on the animal host from which they were isolated. The Agency is
aware that investigators have not found a Cryptosporidium species other
than C. parvum that infects humans (with one highly questionable
exception). To the Agency's knowledge, however, no human infectivity
studies have been conducted to date with any species
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other than C. parvum. Moreover, the taxonomy of the genus
Cryptosporidium is uncertain and changing (Tzipori and Griffiths, 1998;
Fayer et al., 1997). As a result, EPA cannot preclude the possibility
that a new classification of the species comprising the genus
Cryptosporidium may include more than one species capable of infecting
humans. Recently, for example, Peng et al. (1997) analyzed 39 isolates
of C. parvum from humans and cattle and found they could be separated
into either of two genotypes, one of which could infect humans but not
cattle or mice. In the future, these two genotypes may be separated
into two different species.
In addition to the taxonomic issue, the current tests for C. parvum
in stool specimens and water, which involve the microscopic examination
of a stained specimen, may give positive results for Cryptosporidium
species other than C. parvum. Often this results because other
Cryptosporidium species (as well as other microorganisms) may react
with the stains used to detect C. parvum. This is especially true for
the commonly used acid-fast stain. In addition, C. parvum oocysts do
not differ in size and shape from those of C. baileyi and C.
meleagridis (Arrowood, 1997). As a result, it is not necessarily
certain that oocysts in a human fecal specimen identified by a clinical
laboratory as C. parvum are always C. parvum. (In general, clinical
labs do not use a stain or other procedure that can distinguish between
C. parvum and other Cryptosporidium species).
The Agency is aware that a few attempts have been made to infect
one type of animal (e.g., mammals) with Cryptosporidium species
isolated from other types of animals (e.g., birds), generally without
success (Fayer, 1997). In addition, Graczyk et al. (1996b) found that
C. parvum was not transmissible to fish, amphibia, or reptiles.
Nevertheless, until more cross-species transmission data are available,
the Agency cannot foreclose on the possibility that species other than
C. parvum may be infective to humans. In their review of the
literature, Fayer et al. (1990) concluded that the success of
transmission studies is contingent upon not only species specificity,
but also the condition and age of the oocysts, the route of inoculation
of oocysts, and the age and immune status of the recipient. Therefore,
negative results to date on transmission are not necessarily conclusive
regarding host specificity.
EPA believes that it is prudent to set an MCLG at zero not only for
taxonomic reasons but also because of concern that certain populations
are at greater risk of waterborne cryptosporidiosis than others. This
concern is heightened by the fact that currently there is no cure for
cryptosporidiosis (for healthy individuals the disease tends to be self
limiting). Thus, the importance of prevention and avoidance of
infection becomes even more central to EPA's consideration of this
issue. Until the taxonomy of Cryptosporidium has been clarified, EPA
believes that an MCLG of zero for Cryptosporidium at the genus level is
appropriate especially in light of the statutory requirement to
establish MCLGs with ``an adequate margin of safety''.
3. Summary of Major Comments
Regarding the value of the MCLG most commenters supported the
establishment of a MCLG of zero for Cryptosporidium. Reasons that were
given for their support included: (1) Uncertainty exists in the
infective dose for both healthy and vulnerable (immunocompromised)
individuals; (2) an MCLG of zero is consistent with the regulatory
approach for pathogens under the existing Surface Water Treatment Rule
(SWTR); (3) one viable oocyst can cause an infection at least in some
people; and (4) Cryptosporidium has particularly adverse effects on
persons with immune disorders. No commenter proposed an MCLG value
other than zero. Some commenters opposed any MCLG for Cryptosporidium,
arguing that: (1) Current levels of treatment have some level of
effectiveness against Cryptosporidium transmission to drinking water;
(2) uncertainty exists associated with the analytical procedures used
to detect Cryptosporidium; (3) current technology limits the ability to
determine viability, infectivity, and species; and (4) the infectivity
threshold has not been determined.
EPA agrees with the commenters who supported an MCLG of zero for
Cryptosporidium for reasons stated in the previous section. EPA does
not agree with comments opposing any MCLG for Cryptosporidium. While it
is true that current levels of treatment control Cryptosporidium to
some extent, studies have found Cryptosporidium oocysts in filtered
water supplies of some treatment plants (LeChevallier, 1991b;
LeChevallier, 1995). Therefore, the Agency believes that regulation of
Cryptosporidium and enhanced treatment practices are warranted.
Furthermore, the effectiveness of treatment is irrelevant to the
question of setting an MCLG, which asks what is the level of
(uncontrolled) Cryptosporidium in drinking water that will pose no risk
to the health of persons. For the reasons discussed, that level is at
zero. The availability of effective treatment merely ensures that EPA
can regulate to control the health risk from Cryptosporidium reflected
by the MCLG.
Comments which address the uncertainty related to the analytical
method for Cryptosporidium and the fact that current technology does
not allow viability, infectivity, and species to be determined may
relate to the issue of whether EPA establishes an MCL versus treatment
technique requirements for Cryptosporidium. However, they are not
compelling with regard to the public health goal that should be set for
this contaminant.
With regard to the infectivity threshold for Cryptosporidium,
according to a mathematical model based upon the DuPont et al., 1995
data, if an individual ingests a single viable oocyst there is a 0.5%
chance of infection (Haas et al., 1996). It is known that
Cryptosporidium oocysts are capable of causing an infection in both
healthy and seriously ill individuals. Death has been associated with
some cryptosporidiosis cases, particularly among sensitive
subpopulations (i.e., immunocompromised individuals) (Hoxie et al.,
1997). For such reasons, EPA considers an MCLG of zero for
Cryptosporidium to be appropriate.
EPA also received comments on whether the MCLG for Cryptosporidium
should be set at the genus or the species level. Commenters offered
several reasons for supporting an MCLG for C. parvum, as opposed to
Cryptosporidium. Several professed that only C. parvum could infect
humans, and therefore EPA should establish an MCLG based on that
particular species. Commenters also contended that if, in future
regulations, EPA were to establish a treatment technique requirement
based on the Cryptosporidium density in the source water, publishing an
MCLG for Cryptosporidium at the genus level might require systems to
provide an additional level of treatment for Cryptosporidium species
that are not known to be infectious to humans. In contrast, other
commenters who supported the establishment of an MCLG for
Cryptosporidium at the genus level stated that, unless further research
justifies an MCLG at the species level, the MCLG should be set at the
genus level. They reasoned that Cryptosporidium method limitations
argued for setting the MCLG at the genus level.
In response to comments that did not support establishing an MCLG
of zero for Cryptosporidium at the genus level,
[[Page 69486]]
EPA has carefully considered the issue of genus versus species level
for Cryptosporidium. As mentioned earlier, EPA concludes that there
exists much uncertainty regarding Cryptosporidium taxonomy, cross
reactions and cross transmissions. Thus, EPA cannot conclude that these
other species pose no health risk. For reasons mentioned above, the
Agency believes that it is more appropriate to establish an MCLG for
Cryptosporidium at the genus level at this time. This decision does not
affect the level of treatment required under the IESWTR. EPA will
revisit the impact of the MCLG in the context of future rules that
include consideration of risk-based options.
B. Removal of Cryptosporidium by Filtration
1. Today's Rule
Today's final rule establishes a requirement for 2-log removal of
Cryptosporidium for surface water and GWUDI systems serving 10,000 or
more people that must filter under the SWTR. The requirement for at
least 99 percent (2-log) removal of Cryptosporidium applies between a
point where the raw water is not subject to recontamination by surface
water runoff and a point downstream before or at the first customer. As
discussed below, the data available to EPA indicate that rapid granular
filtration systems (i.e., systems using conventional or direct
filtration) when operated under appropriate coagulation conditions and
optimized to meet the turbidity performance standards of the IESWTR
(less than or equal to 0.3 NTU in 95% of the measurements each month
and a maximum of 1 NTU) are achieving at least 2-log removal.
2. Background and Analysis
The 1994 proposal to amend the Surface Water Treatment Rule
included several proposed treatment alternatives. Two of these
alternatives--Alternatives B and C--specifically addressed
Cryptosporidium. Alternative B envisioned treatment options for
Cryptosporidium based on levels of source water occurrence. Alternative
C called for 99% (2-log) removal of Cryptosporidium. EPA was unable to
consider Alternative B for the IESWTR because occurrence data and
related analysis from the ICR sampling and analysis survey discussed
above were not available in time to meet the statutory promulgation
deadline of November 1998. For the reasons outlined below and as
recommended by the M-DBP Advisory Committee, EPA is proceeding with a
2-log removal requirement for Cryptosporidium for surface water and
GWUDI systems serving 10,000 or more people that are required to filter
under the SWTR.
As part of the 1997 M-DBP Advisory Committee process, substantial
new data and information related to removal of Cryptosporidium by
filtration were collected, evaluated and analyzed. The Committee
recommended adoption of a 2-log Cryptosporidium removal requirement for
all surface water systems that serve more than 10,000 people and are
required to filter. The Committee also recommended that systems which
use rapid granular filtration (direct filtration or conventional
filtration treatment) and meet today's strengthened combined filter
effluent turbidity requirements would be in compliance with the
requirement for at least a 2-log removal of Cryptosporidium. Systems
which use slow sand filtration and diatomaceous earth filtration and
meet existing SWTR turbidity performance requirements (less than or
equal to 1 NTU for the 95th percentile or alternative criteria as
approved by the State) also would be in compliance with the requirement
for at least a 2-log removal of Cryptosporidium.
In November of 1997, EPA issued a Notice of Data Availability
(NODA) which discussed new data and information that the Agency had
obtained and analyses that had been developed since the 1994 proposal.
It also summarized recommendations of the M-DBP Advisory Committee on
Cryptosporidium removal. The 1997 NODA requested comment on the new
information, the Advisory Committee's recommendations, and on other
regulatory implications and impacts.
The November 3, 1997 NODA provided new information regarding eight
studies (Patania et al., 1995; Nieminski and Ongerth, 1995; Ongerth and
Pecoraro, 1995; LeChevallier and Norton, 1992; LeChevallier et al.,
1991b; Foundation for Water Research, 1994; Kelley et al., 1995; and
West et al., 1994) that indicated that rapid granular filtration when
operated under appropriate coagulation conditions and optimized to
achieve a filtered water turbidity of less than 0.3 NTU should achieve
at least 2-log of Cryptosporidium removal. These studies were analyzed
as part of the 1997 IESWTR NODA.
3. Summary of Major Comments
In response to the 1994 Proposal, most commenters addressing the
issue of treatment alternatives supported Alternative C which would
require 2-log physical removal of Cryptosporidium. Some opposed any
treatment requirement greater than a 2-log removal due to a lack of
better understanding of dose-response, effectiveness of treatment and
analyses to justify the higher treatment costs involved. Today's rule
requires at least 2-log removal for Cryptosporidium. EPA will revisit
issues related to further control of Cryptosporidium in future
rulemakings.
The majority of commenters to the November 1997 NODA agreed with
the appropriateness of establishing a 2-log removal requirement for
Cryptosporidium in the IESWTR, although some commenters had additional
concerns. One major concern was that a quantitative relationship
between removal of Cryptosporidium and lowered turbidity was premature
and had not been established. EPA believes that the studies identified
in the NODA illustrate the removal efficiencies for Cryptosporidium by
several filtration technologies. While these studies demonstrated a
range of Cryptosporidium log-removals, it is important to realize that
2-log removal was consistently obtainable at turbidity levels of less
than 0.3 NTU when systems were operated under appropriate coagulation
conditions and optimized to achieve a filtered water turbidity level of
less than 0.3 NTU. EPA will continue to assess data for control of
Cryptosporidium by physical removal and disinfection as it becomes
available, and will consider such data in subsequent regulations.
Another significant issue noted by several commenters was that
systems should be provided the opportunity to demonstrate greater log
removal of Cryptosporidium. Consistent with a key point made during M-
DBP Advisory Committee discussions on this issue, EPA takes this
opportunity to note the Agency's position that the requirement for at
least 2-log removal is not intended to prevent a facility from
demonstrating that it can achieve higher than 2-log removal of
Cryptosporidium on a site-specific basis or States from demonstrating
based on site-specific information that a specific facility may
actually be achieving less than 2-log removal of Cryptosporidium even
though it is meeting strengthened turbidity standards of 0.3 NTU for
the 95th percentile and a maximum of 1 NTU.
C. Turbidity Control
1. Today's Rule
Today's rule establishes a number of requirements for filtration
performance and filter monitoring and reporting, outlined below, which
apply to surface
[[Page 69487]]
water systems or ground water under the direct influence of surface
water (GWUDI) that serve 10,000 or more people and are required to
filter under the SWTR. The basis for these provisions is explained at
greater length in background sections of the 1997 IESWTR NODA.
Combined Filter Effluent Requirements
For conventional and direct filtration systems, the turbidity level
of representative samples of a system's combined filter effluent water
must be less than or equal to 0.3 NTU in at least 95 percent of the
measurements taken each month. The turbidity level of representative
samples of a system's filtered water must at no time exceed 1 NTU. For
slow sand and diatomaceous earth filtration, the turbidity level of
representative samples of a system's filtered water must be less than
or equal to 1 NTU in at least 95 percent of the measurements taken each
month and the turbidity level of representative samples of a system's
filtered water must at no time exceed 5 NTU (no change from the
combined filter effluent turbidity requirements in the 1989 SWTR). For
both the maximum and 95th percentile requirements, compliance is
determined based on measurements of the combined filter effluent at
four-hour intervals.
In carrying out these combined effluent requirements, and the
individual filter requirements described below, systems must use
methods for turbidity measurement previously approved by EPA. These are
Method 2130B, published in Standard Methods for the Examination of
Water and Wastewater (19th ed.); Great Lakes Instrument Method 2; and
the revised EPA Method 180.1, approved in August 1993 in Methods for
the Determination of Inorganic Substances in Environmental Samples
(EPA-600/R-93-100). EPA notes that today's rule requires the
measurement of turbidity. Turbidity is a method-defined parameter.
Turbidity therefore is not a candidate for, and will not be subject to,
the performance-based measurements system.
Individual Filter Requirements
Conventional and direct filtration systems must conduct continuous
monitoring of turbidity for each individual filter and must provide an
exceptions report to the State on a monthly basis as part of the
existing combined filter effluent reporting process. Exceptions
reporting must include the following: (1) Any individual filter with a
turbidity level greater than l.0 NTU based on two consecutive
measurements fifteen minutes apart; and (2) any individual filter with
a turbidity level greater than 0.5 NTU at the end of the first 4 hours
of filter operation based on two consecutive measurements fifteen
minutes apart. The system must produce a filter profile for either
situation if no obvious reason for the abnormal filter performance can
be identified. EPA is including a discussion on filter profiles in its
guidance document on turbidity which is currently being developed with
input from stakeholders.
Individual Filter Follow-Up Activities
If an individual filter has turbidity levels greater than l.0 NTU
based on two consecutive measurements fifteen minutes apart at any time
in each of three consecutive months, the system must, in addition to
filing an exceptions report, conduct a self-assessment of the filter.
The self-assessment must consist of at least the following components:
(1) Assessment of filter performance; (2) development of a filter
profile; (3) identification and prioritization of factors limiting
filter performance; (4) assessment of the applicability of corrections;
and (5) preparation of a filter self-assessment report. The system must
conduct the self-assessment within 14 days of the exceedance and report
to the State that the self-assessment was conducted. If an individual
filter has turbidity levels greater than 2.0 NTU based on two
consecutive measurements fifteen minutes apart at any time in each of
two consecutive months, the system must file an exceptions report and
must no later than 30 days following the exceedance arrange for the
conduct of a CPE by the State or a third party approved by the State.
The CPE must be completed and submitted to the State no later than 90
days following the exceedance.
2. Background and Analysis
A primary focus of the 1994 proposal was the establishment of
treatment requirements that would address public health risks from high
densities of pathogens in poor quality source waters and from the
waterborne pathogen Cryptosporidium. Approaches outlined in the 1994
proposal included treatment requirements based on site-specific
concentrations of pathogens in source water and a proposed 2-log
removal requirement for Cryptosporidium by filtration.
EPA specifically requested comment on what criteria, if any, should
be included to ensure that systems optimize treatment plant performance
and on whether any of the existing turbidity performance criteria
should be modified (e.g., should systems be required to base compliance
with the turbidity standards on individual filter effluent monitoring
in lieu of or in addition to monitoring the confluence of all filters;
and should any performance standard value be changed). In addition, the
Agency also requested comment in the 1994 proposal on possible
supplemental requirements for State notification of persistent high
turbidity levels (e.g., broadening the requirements for State
notification of turbidity exceedances).
The 1997 M-DBP Advisory Committee meetings resulted in the
collection, development, evaluation, and presentation of substantial
data and information related to turbidity control. The Committee's
recommendations are reflected in today's rule.
The November 3, 1997 IESWTR NODA discussed new data and information
regarding turbidity control with respect to three areas: (1) Current
turbidity levels at systems throughout the country; (2) individual
filter performance; and (3) turbidity measurement.
Current Turbidity Levels
The November 3, 1997 NODA discussed three data sets that summarized
the historical turbidity performance of various filtration plants
(AWWSC, 1997; Bissonette, 1997; SAIC, 1997b). These were evaluated to
assess the national impact of modifying existing turbidity
requirements. Each of the data sets was analyzed to assess the current
performance of plants with respect to the number of months in which
selected 95th percentile and maximum turbidity levels were exceeded.
The data show that upwards of 90% of the systems are currently meeting
the new requirements of a maximum turbidity limit of 1 NTU. With
respect to the 95th percentile turbidity limit, roughly 78% of the
systems are currently meeting the new requirement of 0.3 NTU. Estimates
for systems needing to make changes to meet a turbidity performance
limit of 0.3 NTU were based on the ability of systems currently to meet
a 0.2 NTU. This assumption was intended to take into account a
utility's concern with possible turbidity measurement error and to
reflect the expectation that a number of utilities will ``aim'' lower
than the regulatory performance level to assure compliance. The
percentage of systems estimated to modify treatment practices to meet
the revised turbidity requirements (i.e., 0.3 NTU 95th percentile and 1
NTU maximum combined filter effluent levels) is
[[Page 69488]]
approximately 50%. Based on the turbidity performance data, EPA assumed
that for systems serving less than 100,000 people, 51.2 percent of the
systems can be expected to make treatment changes to consistently
comply with a monthly 95th percentile limit of 0.3 NTU. Similarly, for
systems serving over 500,000 people, EPA assumed that 41.7 percent can
be expected to make treatment changes to comply with a 0.3 NTU
regulatory limit. For systems serving 100,000 to 500,000 people, EPA
assumed that 46.5 percent of systems can be expected to make changes.
As discussed in greater detail in the November 3, 1997 NODA, the
tighter turbidity performance criteria for combined filter effluent in
today's rule reflect actual current performance for a substantial
percentage of systems nationally. Revising the turbidity criteria
effectively ensures that these systems continue to perform at these
levels (in addition to improving performance of systems that currently
meet existing SWTR criteria but operate at turbidity levels higher than
those in today's final rule).
Individual Filter Performance
Several of the studies published since 1994, considered by both EPA
and the M-DBP Advisory Committee and outlined in the 1997 NODA, note
that the greatest potential for a peak in turbidity (and thus, pathogen
break-through) is near the beginning of the filter run after filter
backwash or start up of operation (Amirtharajah 1988; Bucklin et al.
1988; Cleasby 1990; and Hall and Croll 1996). During a turbidity spike,
significant amounts of particulate matter (including oocysts, if
present) may pass through the filter. Various factors affect the
duration and amplitude of filter spikes, including sudden changes to
the flow rate through the filter, treatment of the filter backwash
water, filter-to-waste capability, and site-specific water quality
conditions. As discussed in the 1997 IESWTR NODA, these issues
highlighted the need to ensure that systems have a greater
understanding of individual filter performance and thus for
establishment of individual filter monitoring and reporting
requirements.
Turbidity Measurement
The November 3, 1997 NODA discussed several issues relating to
measurement of turbidity. It was noted that issues exist concerning the
accuracy and precision of turbidity measurement due to design criteria,
calibration methods, calibration standards, and sampling technique.
Performance evaluation (PE) studies conducted by EPA provide an
indication of the current level of accuracy and precision for turbidity
measurements among different laboratories for a common synthetically
prepared water. In PE studies, PE samples with known turbidity levels
are sent to participating laboratories (which are not informed of the
turbidity level). Laboratories participating in these studies used
turbidimeters from various manufacturers and conducted their analysis
in accordance with calibration and analytical procedures they are
familiar with. Thus, the variability of the results reflects
differences resulting from using different turbidimeter models and
methods and the effects of different laboratory procedures. Four PE
studies were discussed in the NODA with turbidities in the range of
0.35 to 0.72 NTU. The Relative Standard Deviations (RSD) at turbidity
levels considered in these PE studies are slightly below 20%.
3. Summary of Major Comments
In response to the 1994 proposal, EPA received a range of comments
both in support of and in opposition to optimizing existing water
treatment processes to address Cryptosporidium removal. Several
commenters supported tighter turbidity standards as well as monitoring
of individual filters. Other commenters suggested no modifications be
made to turbidity standards until further implementation of the SWTR
and/or further supporting data was gathered.
Commenters on the 1997 NODA provided additional views on the
general subject of filtration performance and turbidity. Commenters
generally supported tightening combined filter effluent performance
standards as well as the establishment of individual filter monitoring
requirements. EPA agrees with these comments, as reflected in today's
rule. EPA also notes that turbidity performance data that reflects
implementation of the SWTR was analyzed as part of the M-DBP Advisory
Committee discussions and was considered by the Committee in developing
the recommendations for turbidity which are reflected in today's rule.
Several commenters discussed the ability of systems to measure
turbidity at low levels (<0.3 NTU) with accuracy and consistency. EPA
believes that the performance evaluation (PE) studies cited in the NODA
provide an indication of the precision and accuracy of turbidity
measurements at low levels. While turbidities in these studies only
ranged from 0.35 to 0.72 NTU, they provided an understanding of the
ability to measure at such levels. EPA recognizes that accurate and
consistent measurements are not only a function of available technology
but also a function of a range of operator/technician factors including
calibration, maintenance, training, and adherence to manufacturer
instructions. In conjunction with the IESWTR, EPA is currently
developing guidance, with stakeholder input, targeted at assisting
owners/operators with understanding turbidity as well as focusing on
the importance of accuracy and consistency in turbidity measurement,
including the low level measurement concerns noted by the commenters.
Many commenters discussed the issue of lime-softening plants and
how the new requirements would affect such plants which, because of the
softening processes, have artificially elevated levels of turbidity.
The IESWTR allows acidification of samples for the combined filter
effluent at lime softening plants. In addition, EPA is allowing systems
that use lime softening to apply to States for alternative exceedance
reporting levels for individual filters if they can demonstrate that
higher turbidity levels in individual filters are due to lime carryover
and not due to degraded filter performance.
Several commenters noted that special filters would present
difficulties in complying with the individual filter monitoring
requirements. While EPA realizes that variations exist in filter
configurations and filters in use at systems throughout the country,
the IESWTR will not seek to address the specific requirements of each
and every one. EPA intends to provide States the flexibility and the
tools necessary to effectively deal with special filters discussed by
the commenters on a more appropriate case-by-case basis.
Another issue raised in public comments was the need to clarify how
public notice requirements in the IESWTR would be integrated with
future public notice requirements under the SDWA. EPA notes that
today's action addresses public notification by using the existing
public notification language for microbiological contaminants in 40 CFR
141.32 (e)(10) for violations of treatment technique requirements under
the IESWTR. EPA takes this opportunity to note that the 1996 amendments
to the SDWA require the Agency to make certain technical 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 IESWTR. Applicable changes in the public notice
[[Page 69489]]
requirements, when they become effective, will supersede today's
provisions. EPA also takes this opportunity to note that today's rule
amends the Consumer Confidence Report Regulation (CCR) to extend the
CCR requirements to apply to Subpart P violations.
Several respondents indicated that it would be necessary to provide
guidance materials to systems to aid in compliance with these rules.
EPA is currently developing a number of guidance manuals, with
stakeholder input, to aid systems in understanding and complying with
requirements. One such manual will address issues of turbidity control
and filter performance.
D. Disinfection Benchmark for Stage 1 DBPR MCLs
1. Today's Rule
Today's rule establishes the disinfection benchmark as a procedure
requiring certain PWSs to evaluate the impact on microbial risk of
proposed changes in disinfection practice. It reflects the
recommendation of the M-DBP Advisory Committee to develop a mechanism
that allows utilities and States working together to assure that
pathogen control is maintained while the Stage 1 DBPR provisions are
implemented. In essence, this procedure involves a PWS charting daily
levels of Giardia lamblia inactivation for a period of at least one
year to create a profile of inactivation performance. The PWS must then
use this profile to determine a baseline or benchmark of inactivation
against which proposed changes in disinfection practices can be
measured. However, only certain systems are required to develop a
profile and keep it on file for State review during sanitary surveys.
When those systems required to develop a profile plan a significant
change in disinfection practice, they must submit the profile, along
with an analysis of how the proposed change will affect the current
disinfection benchmark, to the State for review. The disinfection
benchmark provisions, then, contain three major components:
applicability requirements, characterization of disinfection practice,
and State review of proposed changes in disinfection practice. Each of
these components is discussed in turn below.
Applicability
Systems are required to prepare a disinfection profile if at least
one of the following criteria is met:
(1) TTHM levels are at least 80% of the MCL (0.064 mg/L) as an
annual average
(2) Haloacetic acid (HAA5) levels are at least 80% of the MCL
(0.048 mg/L) as an annual average
In connection with TTHM and HAA5 monitoring to create a
disinfection profile, the following provisions apply:
First, the TTHM annual average must be the annual average during
the same period as is used for the HAA5 annual average. Second, systems
that have collected TTHM and HAA5 data under the ICR must use the
results of samples collected during the last 12 months of monitoring
unless the State determines that there is a more representative annual
data set. Third, systems not required to collect data under the ICR but
which have collected four consecutive quarters of TTHM and HAA5 data
that substantially meet the sample location, handling, and analytical
methods requirements of the ICR may use those data if approved by the
State. (Systems must coordinate with the State to confirm acceptability
of the existing data). Fourth, if the system does not have four
quarters of acceptable HAA5 and TTHM data by the end of 90 days
following the IESWTR promulgation date, the PWS must conduct HAA5 and
TTHM monitoring to determine an annual average. Alternatively, the
system may elect to conduct profiling, as described below, and forego
TTHM/HAA5 monitoring to determine applicability. This monitoring must
be completed no later than 15 months after promulgation of this rule
and conform to the monitoring location requirements of the 1979 TTHM
Rule and the analytical methods in the May 1996 Information Collection
Rule.
Today's rule applies profiling requirements to systems with TTHM or
HAA5 concentrations of at least 80% of the MCL, based upon the M-DBP
Advisory Committee technical recommendation that this level will cover
most systems that might be expected to modify their disinfection
practices to comply with the Stage 1 DBPR. Also, EPA previously
considered this 80% target level at the recommendation of the 1992 Reg
Neg Committee to evaluate Stage 1 DBPR compliance forecasts and costs,
based upon the judgment that most facilities will take additional steps
to ensure continuing MCL compliance if they are at or above this level.
Developing the Profile and Benchmark
Profiling is the characterization of a system's disinfection
practice over a one year period. The system can create the profile by
conducting new daily monitoring and also by using ``grandfathered''
data (as explained below). A disinfection profile consists of a
compilation of daily Giardia lamblia log inactivations (plus virus
inactivations for systems using either chloramines or ozone for primary
disinfection), computed over the period of a year, based on daily
measurements of operational data (disinfectant residual
concentration(s), contact time(s), temperature(s), and, where
necessary, pH).
Grandfathered data are those operational data that a system has
previously collected at a treatment plant during the course of normal
operation. These data may or may not have been used previously for
compliance determinations with the SWTR. Those systems that have all
necessary data to determine profiles using existing operational data
collected prior to promulgation of the IESWTR may use these data in
developing profiles. However, grandfathered data must be substantially
equivalent to operational data that would be collected under this rule.
These data must be representative of inactivation through the entire
treatment plant and not just of certain treatment segments. The State
determines whether grandfathered data are acceptable. (EPA believes
that grandfathered data used in constructing profiles should be the
most recent data available, unless the State determines that there is a
more representative data.)
Systems required to develop disinfection profiles under this rule
must exercise one of the following three options:
Option 1--Systems must conduct daily monitoring as described below.
This monitoring must begin no later than 15 months after IESWTR
promulgation and must continue for a period of one year. The data
collected from this monitoring must be used to develop a one year
disinfection profile;
Option 2--Systems that conduct monitoring under this rule, as
described under Option 1, may also use one or two years of acceptable
grandfathered data, in addition to the one year of new operational
data, in developing the disinfection profile;
Option 3--Systems that have three years of acceptable existing
operational data are not required to conduct monitoring to develop the
disinfection profile under this rule. Instead, they may use
grandfathered data to develop a three year disinfection profile.
Systems must coordinate with the State to confirm acceptability of
grandfathered data no later than 15 months after promulgation of this
rule, but must conduct the required monitoring until the State approves
the system's request to use grandfathered
[[Page 69490]]
data. In order to develop the profile, a system must:
--Measure disinfectant residual concentration (C, in mg/L) before or at
the first customer and just prior to each additional point of
disinfectant addition, whether with the same or a different
disinfectant.
--Determine contact time (T, in minutes) for each residual disinfectant
monitoring point during peak flow conditions. T can be based on either
a tracer study or assumptions based on contactor basin geometry and
baffling. However, systems must use the same method for both
grandfathered data and new data.
--Measure water temperature ( deg.C).
--Measure pH (for chlorine only).
The system must then convert daily operational data to daily log
inactivation values for Giardia (and viruses when chloramines or ozone
is used for primary disinfection) as follows:
--Determine CTcalc for each disinfection segment.
--Determine CT<INF>99.9</INF> (i.e., 3-log inactivation) from tables in
the SWTR using temperature (and pH for chlorine) for each disinfection
segment. Alternatively, States may allow an alternate calculation
procedure (e.g. use of spreadsheet).
--For each segment, log inactivation = (CTcalc/
CT<INF>99.9</INF>) x 3.0.
--Sum the log inactivations for each segment to get the daily log
inactivation.
A log inactivation benchmark is then calculated as follows:
1. Calculate the average log inactivation of all the days for each
calendar month.
2. Determine the calendar month with the lowest average log
inactivation.
3. The lowest average month becomes the critical period for that
year.
4. If acceptable data from multiple years are available, the
average of critical periods for each year becomes the benchmark.
5. If only one year of data is available, the critical period
(lowest monthly average inactivation level) for that year is the
benchmark.
State Review
If a system that is required to produce a disinfection profile
decides to make a significant change in disinfection practice after the
profile is developed, it must consult with the State before
implementing such a change. Significant changes in disinfection
practice are defined as: (1) Moving the point of disinfection (this is
not intended to) include routine seasonal changes already approved by
the State), (2) changing the type of disinfectant or (3) changing the
disinfection process, (4) making other modifications designated as
significant by the State. Supporting materials for such consultation
with the State must include a description of the proposed change, the
disinfection profile developed under this rule for Giardia lamblia
(and, if necessary, viruses), and an analysis of how the proposed
change will affect the current disinfection benchmark. In addition, the
State is required to review disinfection profiles as part of its
periodic sanitary survey.
EPA is currently developing, with stakeholder input, the
Disinfection Benchmarking Guidance Manual for States and systems. This
manual will provide instruction on the development of disinfection
profiles, identification and evaluation of significant changes in
disinfection practices, and considerations for setting an alternative
benchmark. This manual will also provide guidance for systems that are
required to develop a profile based on virus inactivation instead of
Giardia lamblia inactivation.
2. Background and Analysis
A fundamental principle of the 1992-93 regulatory negotiation
reflected in the 1994 proposal for the IESWTR was that new standards
for control of disinfection byproducts must not result in significant
increases in microbial risk. This principle was also one of the
underlying premises of the 1997 M-DBP Advisory Committee's
deliberations, i.e., that existing microbial protection must not be
significantly reduced or undercut as a result of systems taking the
necessary steps to comply with the Stage 1 DBPR. The Advisory Committee
reached agreement on the use of microbial profiling and benchmarking as
a 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.
The strategy of disinfection profiling and benchmarking stemmed
from data provided to the EPA and M-DBP Advisory Committee by PWSs and
reviewed by stakeholders, in which the baseline of microbial
inactivation (expressed as logs of Giardia lamblia inactivation)
demonstrated high variability. Inactivation varied by several log on a
day-to-day basis at any particular treatment plant and by as much as
tens of logs over a year due to changes in water temperature, flow rate
(and, consequently, contact time), seasonal changes in residual
disinfectant, pH, and disinfectant demand (and, consequently,
disinfectant residual). There were also differences between years at
individual plants. To address these variations, M-DBP stakeholders
developed the procedure of profiling a plant's inactivation levels over
a period of at least one year, and then establishing a benchmark of
minimum inactivation as a way to characterize disinfection practice.
This approach makes it possible for a plant that may need to change its
disinfection practice in order to meet DBP MCLs to determine the impact
the change would have on its current level of disinfection and,
thereby, to assure that there is no significant increase in microbial
risk.
3. Summary of Major Comments
In the 1997 IESWTR NODA, EPA requested public comment on all
aspects of the benchmarking procedure, along with any alternative
suggestions, from stakeholders and other interested parties. EPA
specifically requested comment on the following issues: Applicability
requirements; characterization of disinfection practices and
components; use of TTHM and HAA5 data from the same time period instead
of TTHM data from one year and HAA5 data from another; definition of
significant changes to disinfection practice; different approaches to
evaluating possible changes in disinfection practice against a
disinfection profile; and whether the use of grandfathered data, if
available, should be mandatory for profiling and benchmarking.
The majority of comments on the overall benchmarking procedure
outlined in the 1997 IESWTR NODA were positive. Commenters acknowledged
the procedure as a way to maintain microbial control in systems
changing their disinfection practices to comply with DBP MCLs. However,
a significant area of concern expressed in comments was that if PWSs
believe they will be held to a relatively higher regulatory standard as
a result of maintaining a greater level of disinfection than is
currently required, then some PWSs may reduce log inactivation during
profiling in order to lower their benchmarks. EPA emphasizes that
benchmarking is not intended to function as a regulatory standard.
Rather, the objective of the disinfection benchmark is to facilitate
interactions between the States and PWSs for the purpose of assessing
the impact on microbial risk of proposed significant changes to
existing disinfection practices. Final decisions regarding levels of
disinfection beyond
[[Page 69491]]
those required by the SWTR that are necessary to protect public health
will continue to be left to the States. For this reason EPA has not
mandated specific evaluation protocols or decision matrices for
analyzing changes in disinfection practice. EPA is, however, providing
support to the States in making these analyses through the issuance of
guidance. This approach is consistent with a majority of comments on
this issue which requested that EPA not require specific procedures for
the setting of alternative benchmarks but, rather, provide guidance to
States.
Several commenters suggested that instead of requiring profiling
and benchmarking in regulations, EPA should place these procedures in
guidance and allow the States to implement them at their discretion.
EPA considers benchmarking to be an important measure in preventing
significant increases in microbial risk during implementation of the M-
DBP rule cluster. Moreover, States have different statutory authorities
governing what they can mandate and some State agencies are prohibited
by State law from adopting procedures not required by federal
regulations. Consequently, EPA believes the inclusion of benchmarking
as a regulation is warranted.
Commenters were concerned that the benchmarking procedure would not
take into account source water characteristics and that benchmarking
would not be accurate for systems switching from one disinfectant to
another (e.g. chlorine to ozone). EPA will cover both of these topics
in the Disinfection Benchmarking Guidance Manual in sections that
address setting an alternative benchmark. Commenters also asked EPA to
provide instruction on awarding disinfection credits taking into
account possible synergistic effects for different sequential
disinfectants. However, as discussed in other parts of this preamble,
research in this area is not adequate for a disinfection credit scheme
to be developed based on synergistic inactivation.
Most comments submitted to EPA on the issue of applicability
favored using 80% of the MCLs for TTHM and HAA5 as threshold levels for
profiling. Commenters agreed with the EPA and M-DBP Advisory Committee
that these values would capture most of the PWSs likely to change their
disinfection processes to meet DBP MCLs. One commenter proposed that
using TTHM and HAA5 data from two different years would not present a
problem because either one of these parameters can trigger the
profiling requirement. However, the majority of comments on this
subject supported requiring TTHM and HAA5 data to be collected during
the same period since changes in water quality and treatment conditions
influence not only the total quantity of DBPs but also the relative
formation of different DBP species. In today's rule EPA requires that
TTHM and HAA5 data used in determining applicability be collected
during the same period. A few commenters recommended that the
applicability requirements for profiling should also include ozonation
systems with bromate concentrations at least 80% of the MCL (i.e.
8<greek-m>g/L). EPA has elected not to include bromate levels in the
profiling requirements because operational changes, such as dropping
the pH during ozonation, can decrease bromate formation without
reducing disinfection efficacy.
Certain commenters felt that disinfection profiling should only be
required in the event that a system planned to change disinfection
practice and that requiring plants which meet water quality standards
to perform additional studies is unwarranted. EPA believes, however,
that a profile should span all seasons of at least one year to show how
seasonal variations impact the log inactivation provided. Consequently,
waiting to profile until a disinfection change is needed is not
practical because at least one year of monitoring is required and this
could significantly delay the desired modifications. Accordingly, EPA
maintains that profiling in advance of a decision to change
disinfection practices will allow systems to comply with TTHM and HAA5
MCLs in a timely manner without increasing microbial risk. For this
reason, EPA requires profiling of those PWSs most like to modify their
disinfection procedures (i.e. those with TTHM and HAA5 concentrations
at or above 80% of the MCLs).
Many comments advocated allowing the use of grandfathered data in
developing disinfection profiles. However, commenters were
predominantly against making the use of existing operational data
mandatory. They expressed concern that such a requirement would be
inherently inequitable, could entail significant retrieval costs, and
that the data might not be representative of a system's current
operations. EPA believes that grandfathered data will often provide the
most accurate picture of historic levels of microbial disinfection and
encourages its use in constructing the disinfection profile. However,
EPA recognizes that certain problems, such as those identified by
commenters, may justify the exclusion of grandfathered data and,
therefore, has made the use of such data optional. EPA notes that
States may consider issues related to profiling data when determining
whether a proposed change in disinfection practice is acceptable.
The benchmarking procedure in today's rule, therefore, reflects the
concerns of commenters in many respects. On issues such as the use of
grandfathered data, applicability requirements, and evaluating proposed
changes in disinfection practice, the disinfection benchmark
requirements conform to the majority view of comments. In cases where
the rule is at variance with certain commenters' suggestions, such as
making the disinfection benchmarking procedure discretionary and
requiring profiling only in advance of a proposed change in
disinfection practice, EPA has acted in accordance with the need to
achieve risk-risk balancing, which is a central objective of the M-DBP
rule cluster.
E. Definition of Ground Water Under the Direct Influence of Surface
Water
1. Today's Rule
In today's rule, EPA includes Cryptosporidium in the definition of
ground water under the direct influence of surface water (GWUDI). This
change in definition applies only to public water systems that serve
10,000 or more people.
2. Background and Analysis
EPA issued guidance in October 1992 as the Consensus Method for
Determining Groundwater Under the Direct Influence of Surface Water
Using Microscopic Particulate Analysis (MPA). As part of this method, a
microscopic examination is made of the ground water to determine
whether insect parts, plant debris, rotifers, nematodes, protozoa, and
other material associated with the surface or near surface environment
are present. Additional guidance for making GWUDI determinations is
also available (EPA, 1994d, e). Since 1990, States have acquired
substantial experience in making GWUDI determinations and have
documented their approaches (Massachusetts Department of Environmental
Protection, 1993; Maryland, 1993; Sonoma County Water Agency, 1991).
Guidance on existing practices undertaken by States in response to the
SWTR may also be found in the State Sanitary Survey Resource Directory,
jointly published in December 1995 by EPA and the Association of State
Drinking Water Administrators. AWWARF has also
[[Page 69492]]
published guidance (Wilson et al., 1996).
In the existing MPA guidance (EPA, 1992), Cryptosporidia oocysts
are included under the general category of coccidian protozoans, a more
encompassing grouping, some of which are pathogenic to humans. The
score assigned to an occurrence of a coccidian is equivalent to the
score assigned to an occurrence of a Giardia cyst. Thus, it not
anticipated that any change is needed in the MPA scoring methodology to
accommodate the regulation of Cryptosporidium by this rule.
The 1997 NODA summarized the available guidance and additional
information provided by the States and regulated community. Most
recently, Hancock et al. (1998) summarized some of the available data
on parasitic protozoan occurrence in ground water and EPA compiled
additional data on such occurrence in wells (SAIC, 1997a).
3. Summary of Major Comments
The July 29, 1994, Federal Register notice proposed to amend the
SWTR by including Cryptosporidium in the definition of a GWUDI system.
Under the 1994 IESWTR proposal, a system using ground water considered
vulnerable to Cryptosporidium contamination would be subject to the
provisions of the SWTR. EPA proposed that this determination be made by
the State for individual sources using State-established criteria. The
1994 proposed IESWTR also requested comment on revisions to EPA's
guidance on this issue.
Commenters generally agreed that Cryptosporidium should be added to
the definition.
F. Inclusion of Cryptosporidium in Watershed Control Requirements
1. Today's Rule
In today's final rule, EPA is extending the existing watershed
control regulatory requirements for unfiltered systems serving 10,000
or more people to include the control of Cryptosporidium.
Cryptosporidium will be included in the watershed control provisions
for these systems wherever Giardia lamblia is mentioned.
2. Background and Analysis
Watershed control requirements were initially established in 1989
(EPA, 1989b, 54 FR 27496, June 29, 1989) as one of a number of
preconditions that a public water system using surface water must meet
to avoid filtration. As part of its 1994 IESWTR proposal (EPA, 1994b,
59 FR 38839, July 29, 1994), EPA requested comment on extending these
existing watershed control requirements for unfiltered systems at 40
CFR 141.71(b)(2) to include the control of Cryptosporidium. This was
intended to be analogous to and build upon the existing requirements
for Giardia lamblia and viruses; Cryptosporidium would be included in
the watershed control provisions wherever Giardia lamblia is mentioned.
In the November 3, 1997 NODA (EPA, 1997a, 62 FR 59506), the Agency also
requested comment on issues pertaining to monitoring for Giardia and
Cryptosporidium for unfiltered systems serving 10,000 or more people.
As noted above, the SWTR specifies the conditions under which a
system can avoid filtration (40 CFR 141.71). These conditions include
good source water quality, as measured by concentrations of coliforms
and turbidity; disinfection requirements; watershed control; periodic
on-site inspections; the absence of waterborne disease outbreaks; and
compliance with the Total Coliform Rule and the MCL for TTHMs. This
watershed control program under the SWTR must include a
characterization of the watershed hydrology characteristics, land
ownership, and activities which may have an adverse effect on source
water quality, and must minimize the potential for source water
contamination by Giardia lamblia and viruses. The SWTR Guidance Manual
(EPA, 1991a) identifies both natural and human-caused sources of
contamination to be controlled. These sources include wild animal
populations, wastewater treatment plants, grazing animals, feedlots,
and recreational activities. The Guidance Manual recommends that
grazing and sewage discharges not be permitted within the watershed of
unfiltered systems, but indicates that these activities may be
permissible on a case-by-case basis where there is a long detention
time and a high degree of dilution between the point of activity and
the water intake. Although there are no specific monitoring
requirements in the watershed protection program, the non-filtering
utility is required to develop State-approved techniques to eliminate
or minimize the impact of identified point and non-point sources of
pathogenic contamination. The guidance already suggests identifying
sources of microbial contamination, other than Giardia, transmitted by
animals, and points out specifically that Cryptosporidium may be
present if there is grazing in the watershed.
As discussed in the 1997 IESWTR NODA, the Seattle Water Department
summarized the Giardia and Cryptosporidium monitoring results from
several unfiltered water systems (Montgomery Watson, 1995). The central
tendency of this data is approximately 1 oocyst/100L. In light of data
previously discussed that indicates that at least 2-log removal of
Cryptosporidium is achievable with filtration, and considering the
Seattle data analysis, it appears that unfiltered water systems that
comply with the source water requirements of the SWTR have a risk of
cryptosporidiosis equivalent to that of a water system with a well-
operated filter plant using a water source of average quality. EPA
plans to continue to evaluate this issue when additional data becomes
available.
3. Summary of Major Comments
Commenters generally supported specific inclusion of
Cryptosporidium in the watershed control requirements for unfiltered
systems. Some commenters supported watershed control programs in
general without specifically offering an opinion on Cryptosporidium. A
few commenters specifically opposed the inclusion of Cryptosporidium in
the watershed control program, maintaining that other avenues of
watershed control could be promoted without including this organism in
the control plan and that environmental sources of Giardia and
Cryptosporidium were not sufficiently understood.
In response, EPA believes that the environmental sources of
Cryptosporidium are sufficiently understood, as described above, to
support rule requirements. Cryptosporidium cannot be easily controlled
with conventional disinfection practices, and therefore its presence in
source water serving unfiltered surface water systems must be
addressed. EPA also believes that Cryptosporidium poses a potential
hazard to public health and, as noted above, is establishing in today's
rule an MCLG of zero for this pathogenic protozoan. EPA is therefore
amending the existing watershed control requirements for unfiltered
systems to include Cryptosporidium in order to protect public health.
EPA believes that an effective watershed protection program will help
to improve source water quality. Existing guidance already references
the need to guard against pathogenic protozoa including specifically
Cryptosporidium. EPA is proceeding on the presumption that existing
watershed programs already consider and State reviews have evaluated
the adequacy of watershed provisions to assure that raw drinking water
supplies are adequately protected against Cryptosporidium
contamination.
[[Page 69493]]
To the extent this is not the case, however, EPA expects that
unfiltered systems, and States in their annual review, will reassess
their program with regard to this concern and take whatever steps are
necessary to ensure that potential vulnerability to Cryptosporidium
contamination is considered and adequately addressed.
With regard to monitoring, many NODA commenters supported some form
of routine monitoring for Giardia and Cryptosporidium in unfiltered
watershed systems serving 10,000 or more people. A few NODA commenters
supported event monitoring (i.e., an occasion where the raw water
turbidity and/or fecal/total coliform concentration exceeds a specific
value or possibly a site-specific 90th percentile value) for large
unfiltered systems while others were silent on the issue or against
event monitoring. In response, today's final rule does not include
monitoring requirements for unfiltered systems for several reasons. The
IFA method is the only method currently and widely available to
evaluate the presence or absence of Cryptosporidium in a water supply.
However, EPA does not believe this method is appropriate for regulatory
compliance purposes because of its low recovery and variability. EPA
therefore believes that monitoring is most appropriately handled
through guidance at this time. EPA is working with stakeholders to
develop a guidance document for unfiltered systems which will describe
possible monitoring programs. Moreover, the Agency is supporting and
participating in the development of improved Cryptosporidium analytical
methods, including a draft interim method 1622. At the moment, it is
unclear when prototype Cryptosporidium methods (both method 1622, as
well as methods under development to determine viability and
infectivity) will be adequate for regulatory use and compliance
determinations at low concentration levels, but ongoing research
appears promising in this area. As a result, establishment of
Cryptosporidium monitoring requirements for unfiltered systems will be
considered during the development of future microbial rules when EPA
has more information on which to base a regulation (e.g. availability
of better methods, ICR monitoring data, and research characterizing the
relationship between watershed control and pathogen occurrence).
G. Covered Finished Water Reservoirs
1. Today's Rule
In today's final rule EPA is requiring surface water and GWUDI
systems that serve 10,000 or more people to cover all new reservoirs,
holding tanks or other storage facilities for finished water for which
construction begins after the effective date of this rule, February 16,
1999. Today's final rule does not apply these requirements to existing
uncovered finished water reservoirs.
2. Background and Analysis
The proposed IESWTR (EPA, 1994b, 59 FR 38841) indicated that EPA
was considering whether to issue regulations requiring systems to cover
finished water reservoirs and storage tanks, and requested public
comment. The IESWTR Notice of Data Availability (EPA, 1997a, 62 FR
59509) indicated that EPA was considering a requirement that systems
cover all new reservoirs, holding tanks or other storage facilities for
finished water for which construction begins after the effective date
of the rule and invited comment on this issue. The IESWTR NODA also
invited further comment on whether there should be a requirement that
all finished water reservoirs, holding tanks and other storage
facilities be covered as part of the development of future regulations.
As discussed in the 1997 IESWTR Notice of Data Availability, when a
finished water reservoir is open to the atmosphere it may be subject to
some of the environmental factors that surface water is subject to,
depending upon site-specific characteristics and the extent of
protection provided. Potential sources of contamination to uncovered
reservoirs and tanks include airborne chemicals, surface water runoff,
animal carcasses, animal or bird droppings and growth of algae and
other aquatic organisms due to sunlight that results in biomass (Bailey
and Lippy, 1978). In addition, uncovered reservoirs may be subject to
contamination by persons tossing items into the reservoir or illegal
swimming (Pluntze 1974; Erb, 1989). Increases in algal cells,
heterotrophic plate count (HPC) bacteria, turbidity, color, particle
counts, biomass and decreases in chlorine residuals have been reported
(Pluntze, 1974, AWWA Committee Report, 1983, Silverman et al., 1983,
LeChevallier et al. 1997a).
Small mammals, birds, fish, and the growth of algae may contribute
to the microbial degradation of an open finished water reservoir
(Graczyk et al., 1996a; Geldreich, 1990; Fayer and Ungar, 1986;
Current, 1986). In one study, sea gulls contaminated a 10 million
gallon reservoir and increased bacteriological growth, and in another
study waterfowl were found to elevate coliform levels in small
recreational lakes by twenty times their normal levels (Morra, 1979).
Algal growth increases the biomass in the reservoir, which reduces
dissolved oxygen and thereby increases the release of iron, manganese,
and nutrients from the sedi |
