[Federal Register Volume 63, Number 129 (Tuesday, July 7, 1998)]
[Proposed Rules]
[Pages 36742-36806]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-17513]
[[Page 36741]]
_______________________________________________________________________
Part II
Environmental Protection Agency
_______________________________________________________________________
40 CFR Part 131
Water Quality Standards Regulation; Proposed Rule
Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 /
Proposed Rules
[[Page 36742]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 131
[FRL-0W-6118-9]
RIN-2040-AC56
Water Quality Standards Regulation
AGENCY: Environmental Protection Agency.
ACTION: Advance notice of proposed rulemaking.
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SUMMARY: EPA is today publishing this advance notice of proposed rule
making (ANPRM) seeking comments from interested parties on possible
revisions to the Water Quality Standards Regulation at 40 CFR Part 131.
This ANPRM is intended to initiate discussions on what if any changes
are needed in the national water quality standards program to improve
the effectiveness of water quality standards in restoring and
maintaining the quality of the Nation's waters. EPA will consider all
comments before deciding whether to propose revisions to the
regulation. EPA is particularly interested in comments on certain key
portions of the current Water Quality Standards Regulation (the
regulation) contained in 40 CFR Part 131, which establishes
requirements for adoption of water quality standards pursuant to
section 303 of the Clean Water Act (CWA or the Act). This ANPRM
identifies specific issues on which EPA solicits comment. In addition
to the specific issues on which EPA solicits comments, EPA is
interested in comments on any other aspects of the program. EPA
requests comments with the objectives of: supporting watershed or
place-based environmental water quality management, ensuring that
current water quality criteria and water quality assessment science can
be easily incorporated into State and Tribal water quality programs,
and enhancing effective implementation of the Act.
DATES: Written comments must be submitted by midnight January 4, 1999.
ADDRESSES: Send written comments to W-98-01, WQS-ANPRM Comment Clerk,
Water Docket, MC 4101, US EPA, 401 M Street, S.W., Washington, D.C.
20460. Comments may also be submitted electronically to OW-
D[email protected]. The record is available for inspection from
9:00 to 4:00 p.m., Monday through Friday, excluding legal holidays at
the Water Docket, East Tower Basement, USEPA, 401 M St., S.W.,
Washington, D.C. For access to docket materials, please call (202) 260-
3027 to schedule an appointment.
FOR FURTHER INFORMATION CONTACT: Rob Wood at U.S. EPA Standards and
Applied Science Division (4305), 401 M Street SW, Washington, DC 20460
(e-mail: [email protected]) (telephone: 202-260-9536).
SUPPLEMENTARY INFORMATION: EPA will hold a series of full-day public
meetings for the purpose of discussion and debate on the issues
presented in this notice. EPA plans to hold the public meetings during
the 180-day public comment period on this notice. Dates, times and
locations of public meetings will be announced to the public.
A. Potentially Affected Entities
This ANPRM by itself will have no regulatory impact or effect. The
ANPRM does contain EPA interpretations of core areas of the regulation
as well as EPA thinking about how the regulation may need to be
changed. As discussed in more detail below, this ANPRM marks the
beginning of a national dialogue on possible changes to the water
quality standards regulation and program. If changes to the regulation
are proposed and ultimately made final, to the extent such changes
would require and/or authorize changes to State and Tribal water
quality standards, States and authorized Tribes would be affected. If
changes to State and Tribal water quality standards result from any
final rule that EPA may promulgate in the future, entities subject to
compliance with State or Tribal water quality standards would also
potentially be affected. For example, States and Tribes authorized to
implement the National Pollutant Discharge Elimination System (NPDES)
Permit Program would need to ensure that permits they issue include any
limitations on discharges necessary to comply with any water quality
standards established as a result of any subsequent final rulemaking.
Therefore, entities discharging pollutants to waters of the United
States under NPDES could be affected by subsequent proposed and final
rulemaking. Categories and entities that may ultimately be affected
include:
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Examples of potentially
Category affected entities
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State, Tribes and Jurisdictional States, Tribes authorized to
Governments. administer water quality
standards, and jurisdictional
governments.
Industry............................... Industrial dischargers of
pollutants to waters of the
U.S.
Municipalities......................... Publicly-owned treatment works
discharging pollutants to
waters of the U.S.
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This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities that could be affected by any
subsequent final rulemaking. If you have questions regarding the
applicability of this action to a particular entity, consult the person
listed in the preceding FOR FURTHER INFORMATION CONTACT section.
B. Water Docket Information
The record for this notice has been established under docket number
W-98-01 and includes supporting documentation. When submitting written
comments to the Water Docket, (see ADDRESSES section above) please
reference docket number [W-98-01] and submit an original and three
copies of your comments and enclosures (including references). To
ensure that EPA can read, understand and therefore properly respond to
comments, the Agency would prefer that commenters cite the specific
question(s) in the notice to which each comment refers. The questions
presented in this notice for public comment are organized by subsection
and numbered. Each question has a unique number (for example
III.B.3.a., question 1) for this purpose.
Comments must be received or postmarked by midnight January 4,
1999. Commenters who want EPA to acknowledge receipt of their comments
should enclose a self-addressed, stamped envelope. No facsimiles
(faxes) will be accepted.
Electronic comments are encouraged and may be submitted to the
Water Docket (see ADDRESSES section above). Electronic comments must be
submitted as an ASCII file or a WordPerfect file avoiding the use of
special characters and any form of encryption. Electronic comments must
be identified by the docket number, [W-98-01], and be received by
midnight of January 4, 1999. Comments and data will also be accepted on
disks in WP5.1 format or
[[Page 36743]]
ASCII file format. No confidential business information (CBI) should be
sent via e-mail.
The remainder of this Supplementary Information section is
organized as follows:
I. Purpose and Objectives of This ANPRM
A. General Purpose and Vision
B. Objectives
II. Introduction to Water Quality Standards
A. Statutory History
B. Regulatory History
C. Water Quality Guidance for the Great Lakes System
III. Program Areas for Public Comment
A. Introduction
B. Uses
1. Background
2. Refined Designated Uses
3. Existing Uses
a. Protection of Existing Uses
4. Use Attainability
a. Attainability of Uses
b. Removal of Designated Uses
c. Use Attainability Analysis
d. Alternatives to ``Downgrade'' of the Designated Use
i. Variances
ii. Temporary Standards
iii. Ambient-based Criteria
C. Criteria
1. Background
2. Ambient Water Quality Criteria to Protect Aquatic Life
3. Site-Specific Criteria
4. Narrative Water Quality Criteria
5. State or Tribe Derived Criteria
6. Water Quality Criteria for Priority Pollutants
7. Criteria for Non-Priority Pollutants with Toxic Effects
8. Criteria Where Data or Guidance is Limited
9. Toxicity Criteria
10. Sediment Quality Criteria
11. Biological Criteria
12. Wildlife Criteria
13. Physical Criteria
14. Human Health
a. Risk Levels
b. Fish Consumption Assumptions
c. Maximum Contaminant Levels
15. Microbiological Criteria
16. Nutrient Criteria
D. Antidegradation
1. Background
2. General Description of Antidegradation
3. 40 CFR 131.12 (a)(1) ``tier 1''
a. Tier 1 Implementation
4. 40 CFR 131.12 (a)(2) ``tier 2''
a. Identification of ``High Quality'' Waters
b. Tier 2 Implementation
i. Triggers for tier 2 Review
ii. ``Necessary'' Lowering of Water Quality
iii. Identification of ``Important'' Social or Economic
Activities
iv. Tier 2 and Identification of Waters under CWA Section 303(d)
v. Achieving all cost-effective and reasonable best management
practices for nonpoint sources
5. 40 CFR 131.12 (a)(3) ``tier 3''
a. Designating ONRWs
i. Relationship of tier 3 to the Wild and Scenic Rivers Act
b. Tier 3 Implementation
c. Tier 2\1/2\
6. 40 CFR 131.12 (a)(4) ``Thermal Discharges''
E. Mixing Zones
1. Background
2. EPA Policy and Guidance on Mixing Zones
3. State and Tribal Mixing Zone Policies
4. Mixing Zone Requirements
5. Mixing Analyses
6. Narrative Criteria for Mixing Zones
7. Mixing Zones for Bioaccumulative Pollutants
8. Stream Design Flow Policies
F. Wetlands as Waters of the United States
G. Independent Application Policy
1. Introduction
a. Biological Assessments
b. Toxicological Assessments
c. Chemical Assessments
2. Independent Application and Water Quality Assessments
a. Independent Application
b. Alternatives to Independent Application
3. Independent Application and NPDES Permitting
a. Independent Application
b. Alternatives to Independent Application
IV. Summary and Potential Program and Regulation Changes
V. Regulatory Assessment Requirements
A. Executive Order (E.O.) 12866, Regulatory Planning and Review
B. The Regulatory Flexibility Act (RFA) as Amended by the Small
Business Regulatory Enforcement Fairness Act (SBREFA) of 1996
C. Paperwork Reduction Act
I. Purpose and Objectives of This ANPRM
A. General Purpose and Vision
On February 14, 1998, the visionary ``Clean Water Action Plan'' was
announced by the Administrator of EPA and the Secretary of Agriculture.
The ``Clean Water Action Plan'' is a blueprint for restoring and
protecting the Nation's precious water resources. A key element of the
plan is advancement of the watershed approach to water quality
protection. EPA's belief is that refining designated uses and
implementing better more integrated water quality criteria to protect
the refined uses, two important themes of this ANPRM, are essential
steps in carrying out the blueprint presented. Revision of the water
quality standards regulation can be an essential component in
implementing the vision of the ``Clean Water Action Plan.''
States, Tribes and EPA have developed functional water quality
standards programs under the current regulation and these programs have
provided the basis for significant water quality improvement in the
United States. Simply put, the current regulation is not broken.
Rather, with the renewed interest in watershed management combined with
improved methods for water quality assessment, a comprehensive
evaluation for the purpose of strengthening the regulation is
appropriate at this time. EPA and the public need to examine whether
changes in the regulation could enhance water quality management on a
watershed basis and focus resources on areas of greatest concern. A
review of the regulation will also complement similar outreach
discussions EPA is currently undertaking for the purposes of reviewing
the water quality planning and management and total maximum daily load
(TMDL) programs as well as aspects of the NPDES program. EPA is
committed to ensuring that these programs, combined, form an even
stronger integrated basis for water quality planning, priority setting
and implementation on a watershed basis.
In recent years there has been a rising level of scrutiny placed on
water quality standards and the State, Tribal and EPA decisions based
on water quality standards. The increased scrutiny comes from virtually
all parties affected by water quality-based decisions and is evidenced
by the growing tide of challenges to State standards, EPA policies and
guidance, and individual water quality-based decisions. Remaining water
quality problems in the U.S. are often difficult to assess, define and
solve. Once agreed upon, the solutions will be less conventional than
we are used to and may result in different regulatory approaches.
Examples of such problems include aquatic and riparian habitat
destruction from municipal and agricultural run-off and fish tissue
contamination from chemicals with many and diverse sources.
EPA believes that this scrutiny will continue and that an
evaluation of the water quality standards program and its regulatory
and policy underpinnings to identify where these program underpinnings
may need to be strengthened, clarified or revised is imperative. Our
task under the Clean Water Act is to ensure adequate water quality even
where it is difficult to do so. To accomplish this task, EPA envisions
a national water quality standards program in which: the best possible
information on whether designated uses are being attained and how to
attain and maintain them is available and used; water quality criteria
are selected from a wide-ranging menu of scientifically sound criteria
that can be tailored to each watershed; national norms of consistency
and flexibility in State and Tribal water quality standards are clear;
and innovative, cost-effective approaches are
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encouraged. To realize this vision, EPA believes that a structured
national debate is needed to identify a focused set of issues that may
ultimately lead to changes to the water quality standards regulation
and policy.
The ANPRM process allows EPA to begin this work by consulting with
all interested parties to find out what changes, if any, are necessary
and desirable, to make the water quality standards regulation more
responsive to current needs and to identify opportunities for further
clarifications of policy and guidance by EPA. In the fourteen years
since EPA last revised the water quality standards regulation,
interested parties have gained considerable experience in developing
and implementing water quality standards. This experience will provide
valuable information for review of these regulations.
The most significant shift in water quality management programs in
recent years has been the increased emphasis on the use of watershed
based programs. It is increasingly apparent that EPA, States, Tribes,
municipalities and the public share a common view that water quality
programs, including water quality standards, can be better tailored to
the characteristics, problems, risks and implementation tools available
in individual watersheds or basins with meaningful involvement of the
local communities. The water quality standards regulation should ensure
that States and Tribes have the flexibility to define the water quality
standards and hence the environmental objectives of a water body
according to the characteristics of the ecosystem and the needs of the
water's users within the bounds established under the CWA. The
regulation must allow the States and Tribes to tailor water body use
designations and criteria to protect these uses within individual
basins or watersheds based on the needs in the basin. The present use
of broad, jurisdiction-wide use classifications and lists of associated
chemical criteria may be at once too general and too narrow for some
waters, lacking the refinement necessary to tailor water quality
management actions to specific watersheds. This general approach
reflects the historical lack of information on specific basins or water
bodies and the need to ensure that all waters receive adequate
protection. Additionally, it should be made clear how much flexibility
States and Tribes have to adjust use designations as information
improves about whether a designated use or a higher use can be attained
and to reflect natural and human caused changes in water quality that
may have occurred. The challenge for EPA, States and Tribes is to
identify and use opportunities to refine use designations for waters
where it makes sense and better match the water quality criteria to the
refined use, thus making water quality standards more flexible. In
addition, to more effectively implement the standards, the criteria
that are used need to better integrate multiple stressors and their
cumulative impacts in order to more effectively protect designated
uses.
Significant scientific advancements in recent years have added to
the ability to assess environmental impacts and risks related to
changes in water quality. As they are further developed, new and
emerging sophisticated and integrated analytical tools such as
bioassessment, criteria for bioaccumulative chemicals, sediment quality
criteria and toxicity assessments will increasingly allow States,
Tribes, EPA and the public to characterize better the ecological
condition of water resources. At present, this improving capability,
used in a tailored watershed planning and management framework, can
enhance the ability of States and Tribes to characterize and protect
locally agreed upon goals for maintaining and protecting the chemical,
physical and biological integrity of individual basins. In the long
term, chemical, physical and biological assessment methods will
continue to improve. As they do, the water quality standards program
should be designed to accommodate effectively the new science. In the
meantime, progress should not be stalled by incomplete knowledge.
With the new science and assessment methodologies, however, come
new challenges for States and Tribes to identify the resources
necessary to make use of these advances. One of the main themes of this
ANPRM is the need for better data, and new types of data, in order to
support a more refined approach to water quality protection. EPA
recognizes, however, that efforts to obtain such data, and develop the
analytical capacity to integrate it into existing regulatory programs,
could encounter significant resource constraints in some States and
Tribes. EPA is well aware that in order for a new, data-intensive,
watershed-specific approach to succeed, it must be workable for the
States and Tribes that will have to implement it. EPA welcomes comments
regarding concerns over resource constraints and ideas for how to
address them.
The water quality standards program must protect the nation's
waters as envisioned in the CWA. It must establish requirements that
are necessary to attain and maintain healthy, sustainable ecosystems.
It must be flexible enough for States and Tribes to ensure that
standards are protecting water quality in a way that makes sense. EPA
seeks to avoid a program that results in costly requirements that have
little or no environmental benefit. Thus EPA intends to use its
experience and that of the States, Tribes, municipalities, the
regulated community, environmental groups and the general public in
implementing and utilizing water quality standards over the last
fourteen years, to evaluate the regulation and determine if changes are
needed to allow greater State, Tribal and local flexibility to develop
innovative, cost-effective ways to protect water quality.
EPA may determine through the ANPRM process that the concepts
described above can be better integrated into water quality management
decision making through development of new or revised policies and
guidance rather than revisions to the regulation. Because of this
possibility, EPA is reserving its decision whether to propose and
finalize revisions to the regulation. At minimum, EPA believes that any
revisions to the water quality standards regulation should result in a
regulation that can be used to render protective, tailored, site-
specific water quality-based decisions that bear reasonable compliance
costs for the regulated community, as well as reasonable implementation
costs for States, Tribes and EPA. At the same time, the regulation
should allow sufficient flexibility to States and Tribes, if they
choose, to implement water quality standards programs in a manner that
is no more burdensome than under the existing regulation.
B. Objectives
In publishing this ANPRM, EPA is beginning a review of the
regulation in a public forum in an attempt to identify possible
amendments to the regulation, and new guidance or policy that may be
needed to address three distinct objectives. They are: (1) to eliminate
any barriers and develop incentives to enhance State and Tribal
implementation of watershed-based water quality planning and
management; (2) to enhance State and Tribal capability to incorporate
current criteria and water quality assessment science into their water
quality standards programs, and; (3) to improve the regulation so that
it may be implemented more efficiently and effectively (including cost-
effectively). Meeting these three objectives, EPA believes, will
facilitate further water
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quality improvements locally and nationally. EPA urges commenters to
keep all three main objectives in mind when reviewing, analyzing and
commenting on this ANPRM.
II. Introduction to Water Quality Standards
A. Statutory History
The first comprehensive legislation for water pollution control was
the Water Pollution Control Act of 1948 (Pub. L. 845, 80th Congress).
This law adopted principles of State-Federal cooperative program
development, limited federal enforcement authority, and limited federal
financial assistance. These principles were continued in the Federal
Water Pollution Control Act (Pub. L. 660, 84th Congress) in 1956 and in
the Water Quality Act of 1965. Under the 1965 Act, States were directed
to develop water quality standards establishing water quality goals for
interstate waters. By the early 1970's, all the States had adopted such
water quality standards. Since then, States have revised their
standards to reflect new scientific information, the impact on water
quality of economic development and the results of water quality
controls.
Due to enforcement complexities and other problems, an approach
based solely on water quality standards was deemed too weak to make a
difference. The purely water quality-based approach prior to 1972
lacked enforceable Federal mandates and standards, and a strong impetus
to implement plans for water quality improvement. The result was an
incomplete program that in Congress' view needed strengthening. In the
Federal Water Pollution Control Act Amendments of 1972 (Pub. L. 92-500,
Clean Water Act or CWA), Congress established the National Pollutant
Discharge Elimination System (NPDES) whereby each point source
discharger to waters of the U.S. is required to obtain a discharge
permit. The 1972 Amendments required EPA to establish technology-based
effluent limitations that are to be incorporated into NPDES permits. In
addition, the amendments extended the water quality standards program
to intrastate waters and required NPDES permits to be consistent with
applicable State water quality standards. Thus, the CWA established
complementary technology-based and water quality-based approaches to
water pollution control. Now, after nearly 25 years of investment in
technology-based controls and some $70 billion in sewage treatment
plant construction, attention is turning back to water quality
standards as a mechanism to make improvements in water quality beyond
those that have been achieved through technology-based controls.
Water quality standards serve as the foundation for the water-
quality based approach to pollution control and are a fundamental
component of watershed management. Water quality standards are State or
Tribal law or regulation that: define the water quality goals of a
water body, or segment thereof, by designating the use or uses to be
made of the water; set criteria necessary to protect the uses; and
protect water quality through antidegradation provisions. Although the
CWA gives EPA an important role in determining appropriate minimum
levels of protection and providing national oversight, it also gives
considerable flexibility and discretion to States and Tribes to design
their own programs and establish levels of protection above the
national minimum. States and Tribes adopt water quality standards to
protect public health or welfare, enhance the quality of water, and
serve the purposes of the Act. ``Serve the purposes of the Act'' (as
defined in Sections 101(a), 101(a)(2), and 303(c) of the Act) means
that water quality standards should: (1) include provisions for
restoring and maintaining chemical, physical, and biological integrity
of State and Tribal waters, (2) provide, wherever attainable, water
quality for the protection and propagation of fish, shellfish, and
wildlife and recreation in and on the water (``fishable/swimmable''),
and (3) consider the use and value of State and Tribal waters for
public water supplies, propagation of fish and wildlife, recreation,
agricultural and industrial purposes, and navigation. See 40 CFR 131.2.
Section 303(c) of the CWA establishes the basis for the current
water quality standards program. Section 303(c):
1. Defines water quality standards;
2. Identifies acceptable beneficial uses: public water supply,
propagation of fish and wildlife, recreational purposes, agricultural
and industrial water supplies and navigation;
3. Requires that State and Tribal standards protect public health
or welfare, enhance the quality of water and serve the purposes of the
Act;
4. Requires that States and Tribes review their standards every
three years;
5. Establishes the process for EPA review of State and Tribal
standards, including where necessary the promulgation of a superseding
Federal rule in cases where a State's or Tribe's standards are not
consistent with applicable requirements of the CWA or in situations
where the Administrator determines that Federal standards are necessary
to meet the requirements of the Act.
The decade of the 1970's saw State and EPA attention focus on
creating the infrastructure necessary to support the NPDES permit
program and development of technology-based effluent limitations. While
the water quality standards program continued, it was a low priority in
the overall CWA program. In the early 1980's, it began to be recognized
that greater attention to the water quality-based approach to pollution
control would be needed to effectively protect and enhance all of the
nation's waters.
The first statutory evidence of this was the enactment of a CWA
requirement that after December 29, 1984, no construction grant could
be awarded for projects that discharged into stream segments which had
not, at least once since December 1981, had their water quality
standards reviewed and revised or new standards adopted as appropriate
under Section 303(c). (Public Law 97-117, Section 24, ``Revised Water
Quality Standards.'') The efforts by the States to comply with this
one-time requirement essentially made the States' water quality
standards current as of that date for segments with publicly-owned
treatment works (POTWs) discharging into them.
Additional impetus to the water quality standards program occurred
on February 4, 1987, when Congress enacted the Water Quality Act of
1987 (Pub. L. 100-4). Congressional impatience with the lack of
progress in State adoption of standards for toxics (which had been a
national program priority since the early 1980's) resulted in the 1987
adoption of new water quality standard provisions in the Water Quality
Act amendments. These amendments reflected Congress' conclusion that
toxic pollutants in water are one of the most pressing water pollution
problems. One concern Congress had was that States were relying, for
the most part, on narrative criteria to control toxics (e.g., ``no
toxics in toxic amounts''), which made development of effluent
limitations in permits difficult. To remedy this, Congress adopted
section 303(c)(2)(B), which essentially required development of numeric
criteria for those water body segments where toxic pollutants were
likely to adversely affect designated uses.
The 1987 Amendments gave new teeth to the control of toxic
pollutants. As Senator Mitchell put it, Section 303(c)(2)(B) requires
``States to identify waters that do not meet water quality
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standards due to the discharge of toxic substances, to adopt numerical
criteria for the pollutants in such waters, and to establish effluent
limitations for individual discharges to such water bodies.'' (From
Senator Mitchell, 133 Cong. Rec. S733.) To assist States in complying
with Section 303(c)(2)(B), EPA issued program guidance in December 1988
and instituted an expanded program of training and technical
assistance.
Section 518 was another major addition in the 1987 Amendments to
the Act. This section extended participation in the water quality
standards and 401 certification programs to certain Indian Tribes. The
Act directed EPA to establish procedures by which a Tribe could
``qualify for treatment as a State,'' at its option, for purposes of
administering the standards and 401 certification programs. The Act
also required EPA to create a mechanism to resolve disputes that might
develop when unreasonable consequences arise from a Tribe and a State
or another Tribe adopting different water quality standards on common
bodies of water.
Furthermore, with the 1987 Amendments, the Act explicitly
recognized EPA's antidegradation policy for the first time. The intent
of the antidegradation policy in EPA's regulation was and is to protect
existing uses and the level of water quality necessary to protect
existing uses and to provide a means for assessing activities that may
impact high quality waters and ruling on whether such projects could
proceed. Section 303(d)(4) of the Act requires that water quality
standards in those waters that meet or exceed levels necessary to
support designated uses ``may be revised only if such revision is
subject to and consistent with the antidegradation policy established
under this section.''
B. Regulatory History
In the late 1960's and early 1970's the water quality standards
program was initiated and administered based on minimal guidance and
Federal policies--many of which are still reflected in the water
quality standards program today.
EPA first promulgated a water quality standards regulation in 1975
(40 CFR 130.17, 40 FR 55334, November 28, 1975) as part of EPA's water
quality management regulations mandated under Section 303(e) of the
Act. As discussed earlier, the standards program had a relatively low
priority during this time. This was reflected in the minimal
requirements of the first Water Quality Standards Regulation. Few
requirements on designating water uses and procedures were included.
The Regulation was general, requiring ``appropriate'' water quality
criteria necessary to support designated uses and incorporating the
antidegradation policy. Toxic pollutants or any other specific criteria
were not mentioned.
Some States developed detailed water quality standards regulations
while others adopted only general provisions which proved to be of
limited use in the management of increasingly complex water quality
problems and created disparities in requirements on regulated entities.
The few water quality criteria that were adopted addressed a limited
number of pollutants and primarily described fundamental water quality
conditions (e.g., pH, temperature, dissolved oxygen and suspended
solids) or dealt with conventional pollutants.
In the late 1970s, EPA determined that existing State water quality
standards needed to be better developed. EPA moved to strengthen the
water quality program to complement the technology based controls. EPA
amended the Water Quality Standards Regulation to explicitly address
toxic criteria requirements in State standards and other legal and
programmatic issues. November 8, 1983 (54 FR 51400). This regulation is
more comprehensive than its predecessor and includes more specific
regulatory and procedural requirements. The 1983 regulation created the
concept of use attainability analysis, added detail on the adoption of
numeric criteria including authorization for site-specific criteria,
and listed specific procedural requirements and definitions not
included in the original 1975 regulation. The regulation specified the
roles of the States and EPA and the administrative requirements for
States in adopting and submitting their standards to EPA for review. It
also delineated the EPA requirements for review of State standards and
promulgation of federal standards.
The 1983 regulation provided States (and subsequently in 1991)
Tribes with the option of refining their use designation process by
allowing them to establish subcategories of uses, such as cold water
and warm water aquatic life designations. The 1983 regulation also
clarified that States (and subsequently Tribes) may adopt discretionary
policies affecting the implementation of standards, such as mixing
zones, low flows, and variances.
In support of the 1983 Regulation, EPA simultaneously issued
program guidance entitled Water Quality Standards Handbook (December,
1983). The Handbook provided guidance on the interpretation and
implementation of the Water Quality Standards Regulation. This document
also contained information on scientific and technical analyses that
are used in making decisions that would impact water quality standards.
EPA also developed the Technical Support Document for Water Quality-
Based Toxics Control (EPA 44/4-85-032, September, 1985) (TSD) which
provided additional guidance for implementing State water quality
standards. In 1991, EPA revised and expanded the TSD. (EPA 505/2-90-
001, March 1991). In 1994, EPA issued the Water Quality Standards
Handbook: Second Edition (EPA-823-B-94-006, August 1994).
To accelerate compliance with CWA section 303(c)(2)(B) (created by
the 1987 Water Quality Act), EPA started action in 1990 to promulgate
numeric water quality criteria for those States that had not adopted
sufficient water quality standards for toxic pollutants. The intent of
the rulemaking, known as the National Toxics Rule, was to strengthen
State water quality management programs by increasing the level of
protection afforded to aquatic life and human health through the
adoption of all available criteria for toxic pollutants listed under
307(a) of the CWA (priority pollutants) present or likely to be present
in State waters. This action culminated on December 22, 1992, with EPA
promulgating Federal water quality criteria for priority toxic
pollutants for 14 States and Territories (see 57 FR 60848).
Subsequent to the promulgation of criteria under the National
Toxics Rule, EPA altered its national policy on the expression of
aquatic life criteria for metals. On May 4, 1995 at 60 FR 22228, EPA
issued a stay of several metals criteria (expressed as total
recoverable metal) previously promulgated under the National Toxics
Rule for the protection of aquatic life. EPA simultaneously issued an
interim final rule that changed these metal criteria promulgated under
the National Toxics Rule from the total recoverable form to the
dissolved form.
The Water Quality Standards Regulation was amended in 1991 to
implement Section 518 of the Act to expand the standards program to
include Indian Tribes (56 FR 64893, December 12, 1991). EPA added 40
CFR 131.7 to describe the requirements of the issue dispute resolution
mechanism (to resolve unreasonable consequences that may arise between
a Tribe and a State or another Tribe when differing water quality
standards have been adopted for a common body of water) and 40 CFR
131.8 to establish the
[[Page 36747]]
procedures by which a Tribe applies for authorization to assume the
responsibilities of the water quality standards and section 401
certification programs.
Fourteen years since its last major revision, the water quality
standards regulation is undergoing review and potential revision in
light of experiences gained in its implementation by States, Tribes,
EPA and the public. The review is intended to reflect the changing
nature of the program and to identify specific changes that will
strengthen water quality protection and restoration, facilitate
watershed management initiatives, and incorporate evolving water
quality criteria and assessment science into water quality standards
programs. Based on the review and the comments expected on the ANPRM,
EPA may decide to revise parts of the regulation and/or change some of
its existing policies and guidance for the water quality standards
program.
Water quality standards are essential to a wide range of surface
water activities, including: (1) setting and revising water quality
goals for watersheds and/or individual water bodies, (2) monitoring
water quality to provide information upon which water quality-based
decisions will be made, (3) calculating total maximum daily loads
(TMDLs), waste load allocations (WLAs) for point sources of pollution,
and load allocations (LAs) for natural background and nonpoint sources
of pollution, (4) developing water quality management plans which
prescribe the regulatory, construction, and management activities
necessary to meet the water body goals, (5) calculating NPDES water
quality-based effluent limitations for point sources, in the absence of
TMDLs, WLAs, LAs, and/or water quality management plans, (6) preparing
various reports and lists that document the condition of the State's or
Tribe's water quality, and (7) developing, revising, and implementing
an effective section 319 management program which outlines the State's
or Tribe's control strategy for nonpoint sources of pollution.
Note: The term ``State'' as used in this Notice refers to the
fifty States, all Territories of the United States, and the District
of Columbia. The term ``Tribe'' or ``Tribal'' as used in this Notice
generally refers to all Indian Tribes authorized to administer the
water quality standards. On occasion, the term ``Tribe'' or
``Tribal'' refers to Indian Tribes that are eligible to seek
authorization to administer the water quality standards, but have
not yet secured such authorization. There are some parts of the law
and regulation where ``State'' is now interpreted to mean ``State or
Tribe.''
C. Water Quality Guidance for the Great Lakes System
On March 23, 1995, EPA published in the Federal Register its Water
Quality Guidance for the Great Lakes System (60 FR 15366, March 23,
1995) (Great Lakes Guidance). The Guidance consists of water quality
criteria for 29 pollutants to protect aquatic life, wildlife, and human
health, and detailed methodologies to develop criteria for additional
pollutants; implementation procedures to develop more consistent,
enforceable water quality-based effluent limits in discharge permits,
as well as TMDLs of pollutants that can be allowed to reach the Great
Lakes and their tributaries from all sources; and antidegradation
policies and procedures.
Section 118(c)(2) of the Clean Water Act (CWA) (Pub. L. 92-500 as
amended by the Great Lakes Critical Programs Act of 1990 (CPA), Pub. L.
101-596, November 16, 1990) required EPA to publish proposed and final
water quality guidance on minimum water quality standards,
antidegradation policies, and implementation procedures for the Great
Lakes System. EPA responded to these requirements by initiating a
rulemaking, publishing the Proposed Water Quality Guidance for the
Great Lakes System (proposed Guidance) in the Federal Register on April
16, 1993 (58 FR 20802). EPA also published four subsequent documents in
the Federal Register identifying corrections and requesting comments on
additional related materials. EPA received over 26,500 pages of
comments, data, and information from over 6,000 commenters in response
to these documents and from meetings with members of the public.
After reviewing and analyzing the information in the proposal and
these comments, EPA developed and published the Great Lakes Guidance,
codified at 40 CFR Part 132. Part 132 contains six appendixes of
detailed methodologies, policies, and procedures. Detailed discussion
of the final Guidance is provided in ``Final Water Quality Guidance for
the Great Lakes System: Supplementary Information Document'' (SID),
(EPA, 1995, 820-B-95-001) and in additional technical and supporting
documents which are available in the docket for the rulemaking. Copies
of the SID and other supporting documents are also available from EPA
in electronic format, or in printed form for a fee upon request.
Developing the Great Lakes Guidance was an enormous effort based on
extensive public comment and analysis on some of the same issues that
are addressed in this ANPRM. One principal difference between the
provisions in the Great Lakes Guidance and the regulation, policy and
guidance that is the subject of this ANPRM is that where the Great
Lakes Guidance addressed programs in the Great Lakes States only, this
ANPRM addresses the national water quality standards regulation and
program, and thus the programs of all States and Tribes with water
quality standards authority. Where the Great Lakes Guidance addressed
an issue or issue area that is also addressed in the ANPRM, that
analysis and conclusion may or may not be relevant to the discussion of
the national program. Where it is, today's ANPRM identifies the
specific relevant Great Lakes Guidance provisions in the specific issue
discussions. Many of the provisions in the Great Lakes Guidance were
developed to address the unique problems in the Great Lakes Basin that
stem from known contamination by bioaccumulative chemicals and the long
retention time of water in the Lakes. Commenters should keep in mind
that the Great Lakes provisions were derived for States that are in the
Great Lakes Basin in whole or part and should consider the uniqueness
of the Great Lakes Basin when evaluating Great Lakes Guidance
provisions for application outside of the Great Lakes Basin.
III. Program Areas for Public Comment
A. Introduction
Entering its 33rd year, the water quality standards program has
begun to evolve from one with a narrow focus on establishing water body
uses and adopting chemical criteria for basic water quality
characteristics addressing the most obvious sources of pollution to a
more comprehensive program. In recent years the scientific community
has developed greater knowledge of the full range of stressors
adversely impacting surface waters. EPA believes the water quality
standards program should evolve to keep pace with expanding science to
address water quality problems in a more comprehensive way,
accommodating more specific and sophisticated water use
classifications, criteria for more pollutants, new forms of criteria
and companion ecological and health indicators, and closer integration
with other programs. At the same time, EPA realizes that such an
evolution could require a significant increase in analytical resources
from States, Tribes and the regulated community, and that changes to
the existing program must be structured in a way that is workable.
[[Page 36748]]
This is an appropriate time to begin a structured national debate
aimed at identifying the focused changes necessary to strengthen the
underpinnings of water quality standards and implementation. In the
fourteen years since the regulation was last revised, there have been
numerous scientific developments, statutory changes, court decisions,
and implementation issues affecting the water quality standards
program. The shift in program focus beyond just chemical contamination
to include ecosystem protection and watershed approaches necessitates
reexamining basic program concepts. In addition, there is an
opportunity to address possible barriers to effective water quality
improvements where it is determined that regulatory changes are
possible under existing law.
In recent years, EPA has heard from the States and Tribes as well
as the environmental and regulated communities regarding the necessity
and focus of a revision to the water quality standards regulation. As
indicated by the wide range of issues and options presented in this
advance notice, views of the different stakeholder groups often differ
considerably. Many stakeholders believe that a revised regulation is
needed for continued improvements in water quality protection. Others
believe changes are needed to allow more flexible, cost-effective
approaches by States and Tribes. Conversely, many stakeholders have
said that the regulation is sufficient and does not need to be
reviewed.
A key issue presented here relates to the degree of specificity
necessary should EPA revise the regulation. There are many who support
a more flexible regulation to allow States and Tribes to address new
and changing circumstances. Under a more flexible regulation, States
and Tribes could more easily tailor their programs to deal with
pressing water quality restoration and protection needs that are not
well addressed presently. Others support a regulation with more
specific regulatory requirements. The latter would promote a more
consistent minimal level of protection in State and Tribal water
quality standards, provide more clarity on standards issues, and serve
as a stronger tool in encouraging States and Tribes to take appropriate
restoration and protection actions. EPA urges commenters to consider
the appropriate balance between flexibility, national consistency, and
consistency within States and Tribes when commenting on any of the
ideas presented in this notice.
One of the outcomes of this ANPRM and follow-on actions can be
establishment of a clearer set of national minimum policies and
implementation procedures on which EPA will reliably and predictably
base its approval and disapproval decisions on State and Tribal water
quality standards submittals. EPA remains committed to making
consistent decisions from State to State and Tribe to Tribe and State
to Tribe to meet our obligation to ensure an appropriate level of
protection nationally and that the goals of the Act are achieved.
Clarifying these national norms will serve to better articulate the
norms of protection from State to State and Tribe to Tribe and State to
Tribe and also to clarify national norms of flexibility. Defining the
appropriate level of consistency, in turn, defines the appropriate
degree level of flexibility. In addition, establishing norms of
consistency and flexibility should help to resolve State or Tribal
differences with EPA on water quality standards early in the process,
before the approval/disapproval stage.
While the following discussion describes specific areas and issues
for public review, the public is welcome to comment on any aspect of
the water quality standards program. EPA emphasizes, however, that
publication of this Notice does not commit the Agency to proceeding
with a regulatory change. EPA has not decided whether it will, in fact,
propose regulatory amendments, and, if proposed, how extensive that
effort might be. This decision will be made after considering the
comments received and the need to address other priority activities as
well as any Congressional and Executive Branch directives. A potential
outcome of this public review may be additional guidance and/or
policies rather than regulatory changes.
EPA has not determined the next steps it will take after evaluation
of all the comments received on this ANPRM. It is likely that any
follow-on proposed rule to amend 40 CFR 131 would focus on a relatively
narrow set of issues and that many other issues could be resolved
through policy and guidance. EPA requests that commenters identify the
five to seven issues considered highest priority for possible
regulatory amendments. The summary section at the end of this notice
contains a brief summary of the potential changes to the water quality
standards regulation that are discussed and considered in this ANPRM.
The list of potential changes includes the full range of potential
changes to the regulation on which EPA is specifically requesting
comment. Each potential change to the regulation is discussed in detail
in the corresponding section of the ANPRM.
B. Uses
1. Background
Section 131.10 of the current regulation describes States' and
authorized Tribes' responsibilities for designating and protecting
uses. The regulation requires that States and Tribes specify the water
uses to be achieved and protected; requires protection of downstream
uses; allows for sub-category and seasonal uses, for instance, to
differentiate between cold water and warm water fisheries; sets out
minimum attainability criteria; lists six factors of which at least one
must be satisfied to justify removal of designated uses which are not
existing uses; prohibits removal of existing uses; establishes a
mandatory upgrading of uses which are existing but not designated; and
establishes conditions and requirements for conducting use
attainability analyses.
These provisions make a distinction between existing and designated
uses and set out specific requirements to ensure protection of these
two broad use categories. Designated uses are defined as those uses
specified in water quality standards for each water body or segment
whether or not they are being attained. EPA interprets existing uses as
those uses actually attained in the water body on or after November 28,
1975 (the date of EPA's initial water quality standards regulation),
whether or not they are included in water quality standards. 40 CFR
131.3(e). Designated uses focus on the attainable condition while
existing uses focus on the past or present condition. Section 131.10
then links these two broad use categories in a manner which intends to
ensure that States and Tribes designate appropriate water uses,
reflecting both the existing and attainable uses of each water body.
For this discussion it is important to consider both the distinction
between and linkage of designated and existing uses.
It is in designating uses that States and Tribes establish the
environmental goals for their water resources, and it is in designating
uses that States and Tribes are allowed to evaluate the attainability
of those goals. Because water quality standards perform the dual
function of establishing water quality goals and ultimately serving as
the regulatory basis for water quality-based treatment controls and
strategies, typically, although not exclusively, via water quality
criteria protecting those uses, a State or Tribe often weighs the
environmental, social and economic
[[Page 36749]]
consequences of its decisions in designating uses. The regulation
allows the State or Tribe some flexibility in weighing these
considerations and adjusting these goals over time. Reaching a
conclusion on the uses that appropriately reflect the potential for a
water body, determining the attainability of those goals, and
appropriately evaluating the consequences of a designation, however,
can be a difficult and controversial task. Appropriate application of
this process involves a balancing of environmental, scientific,
technical, and economic and social considerations as well as public
opinion and is therefore one of the most challenging areas of the
current regulation.
To direct this decision making-process, the regulation establishes
requirements that must be followed when designating uses or concluding
that attaining a use is infeasible. When performing this attainability
analysis, a State or Tribe considers physical, chemical, biological and
economic factors that may limit the potential for achieving the goal
use.
EPA's current water quality regulation effectively establishes a
``rebuttable presumption'' that ``fishable/swimmable'' uses are
attainable and therefore should apply to a water body unless it is
affirmatively demonstrated that such uses are not attainable. EPA
believes that the rebuttable presumption policy reflected in these
regulations is an essential foundation for effective implementation of
the Clean Water Act as a whole. The ``use'' of a water body is the most
fundamental articulation of its role in the aquatic and human
environments, and all of the water quality protections established by
the CWA follow from the water's designated use. This approach preserves
States' and Tribes' paramount role in establishing water quality
standards, in this instance, in weighing any available evidence
regarding the attainable uses of a particular water body. The
rebuttable presumption approach does not restrict the discretion that
States and Tribes have to determine that ``fishable/swimmable'' uses
are not, in fact, attainable in a particular case. Rather, if the water
quality goals articulated by Congress are not to be met in a particular
water body, the regulations simply require that such a determination be
based upon a credible, ``structured scientific assessment'' of use
attainability.
Because there is a presumption that the uses specified in sections
101(a)(2) and 303(c) of the Clean Water Act are attainable (protection
and propagation of fish, shellfish and wildlife and recreation in and
on the water [101(a)(2)]; public water supplies, propagation of fish
and wildlife, recreational purposes, agricultural purposes, and
navigation [303(c)(2)(A)]), the criteria for overcoming that
presumption are carefully circumscribed. The economic use removal test,
for example, requires a showing that the cost of compliance with the
use(s) would result in ``substantial and widespread economic and social
impact.'' This is a high threshold to ensure that the interim goals of
section 101(a)(2) and the section 303(c) uses are not abandoned without
appropriate cause.
The general construction of the Sec. 131.10 requirements for
designating uses, supplemented with specific Agency guidance, has
worked well in most situations over the last 14 years, and the use
designation process is well established in State and Tribal water
quality standards programs. There are, however, a number of new issues
that have arisen since the 1983 regulation was promulgated. Often these
new issues are associated with site-specific decision-making, and EPA
expects the trend toward site-specific application of water quality
standards will accelerate as States and Tribes begin implementing
watershed protection programs, using field biological information to
more precisely describe aquatic communities to be protected or
restored, and applying new watershed or ecosystem-specific approaches
to criteria development. As explained in the ``Objectives'' discussion
in this document, one of the principal reasons for this notice is to
determine whether or not the current regulation is sufficiently
flexible to accommodate an expected shift in program emphasis beyond
chemical contaminants to ecosystem protection and watershed approaches
that will necessarily place greater emphasis on integrated assessments
of both chemical and non-chemical stressors and watershed-specific
decision-making.
While it is important to identify potential barriers to needed
flexibility, commenters should identify, as well, any changes or
clarification that may be needed to ensure that an appropriate level of
national consistency is maintained across and within all jurisdictions.
In this section of the notice, EPA seeks comment on the following
issues: (1) refined designated uses with more focus on watersheds and
ecosystems, (2) existing uses, (3) attainability and removal of
designated uses, and (4) alternatives to removal of designated uses.
2. Refined Designated Uses
The current regulation at 40 CFR 131.10(a), based on section 303 of
the CWA, requires that States and authorized Tribes specify appropriate
water uses to be achieved and protected, taking into consideration the
use and value of water for public water supplies, protection and
propagation of fish, shellfish and wildlife, recreation in and on the
water, agricultural, industrial, and other purposes including
navigation. The regulation also allows, but does not require, States
and Tribes to identify more specific sub-categories of these general
use categories.
Over the years, States and Tribes have created many different use
classification systems ranging from a straightforward replication of
uses specifically listed in section 303 of the Act to more complex
systems that express designated uses in very specific terms or
establish sub-classifications which identify different levels of
protection. For example, some States simply specify ``water supply'' as
a use classification applicable throughout the State while others may
identify several specific sub-categories related to the quality of the
raw water supply and anticipated treatment requirements. Similarly,
some States designate general ``aquatic life'' uses while others list a
variety of sub-categories based on a range of aquatic community types
which may include descriptions of core aquatic species representative
of each sub-category. Although a variety of approaches have evolved and
become established in State and Tribal programs, the current regulation
is not specific about the level of precision States or Tribes must
achieve in designating uses.
There are advantages and drawbacks for either the general or
specific use classification systems and it is not clear that either is
necessarily superior in ensuring full protection of State or Tribal
water quality. There is, however, a need for the use designation
process, whether implementing a general or specific classification
system, to clearly articulate and differentiate intended levels of
protection with enough specificity so that decision-makers can
appropriately develop and implement the standards on a site-or
watershed-specific basis and so that the public can understand,
identify with, and influence the goals set for waters they care about.
Lack of precision in uses and criteria assigned to protect those
uses can inadvertently result in either a lesser or greater level of
protection than was actually intended when the water quality standards
were adopted. Although the designated use specificity
[[Page 36750]]
issue may apply to any of the Section 303 general use categories, it
may be most relevant for aquatic life uses. Aquatic communities can
vary significantly from water body-to-water body. As noted above,
however, State and Tribal use classifications generally do not reflect
the variability among aquatic community types and may list, instead,
very general descriptions such as ``aquatic life'' as the designated
use. Where this is the case, it is possible that measurable changes in
aquatic community composition or production could occur at a specific
site and still satisfy the definition of ``aquatic life,'' unless
somewhere in its process the State or Tribe has documented information
about its specific intent in applying the ``aquatic life''
classification to each water body. For example, an activity that causes
the discharge of sediment, altering the physical habitat in the
receiving water body, could result in a measurable change in aquatic
community structure and function (e.g., the types of aquatic species
found in that segment). Yet, that activity may arguably satisfy a
general ``aquatic life'' use protection requirement simply because of a
lack of specificity in the regulatory description of that designated
use. In this case, lack of precision in the designation or description
of the use could result in under protection of the resource, unless
somewhere in the State or Tribal process an intended level of
protection is specified.
Alternatively, lack of precision in uses and assigned criteria
could result in standards that are over protective, resulting in
application of unnecessary control requirements. In assigning criteria
to protect general use classifications, a State or Tribe must ensure
that the criteria are sufficiently protective to safeguard the full
range of waters in the State or Tribe (i.e., criteria would be based on
the most sensitive use). While this approach will result in full
protection of all State or Tribal waters, the approach has been
challenged, especially for aquatic life uses, where evidence suggests
that the general use and criteria will require controls more stringent
than needed to protect either the existing or potential aquatic
community for a specific water body. Although EPA supports broad
application of statewide or tribe-wide criteria to ensure that
sensitive uses are protected where site-specific information is
lacking, the Agency's current thinking is that there is a growing need
to more precisely tailor use descriptions and criteria to match site-
specific conditions, ensuring that uses and criteria provide an
appropriate level of protection which, to the extent possible, is
neither over nor under protective. This concept was reflected in the
Agency's 1994 Combined Sewer Overflow Policy (59 FR 18688).
The level of protection issue is one of both use and criteria. To
have a meaningful effect, a more precise use description must be
accompanied by more focused criteria, appropriately tailored to the
refined use description. EPA recognizes that, at present, national or
statewide or tribe-wide criteria generally are not sufficiently precise
to distinguish among all of the various sub-categories of uses. As
water quality standards issues become more watershed-specific or site-
specific, however, the trend will very likely be toward more specific
use descriptions and; because the essential purpose of the criteria is
to describe, evaluate attainment of, and protect the designated use;
more site-specific criteria development.
A potential constraint for refining the aquatic life uses would be
the resource commitment often associated with developing a
comprehensive biological database. Because of the resource constraints,
it may be difficult for a State or Tribe to develop designated uses (or
use descriptions) for each segment that include a detailed biological
description of the aquatic community to be protected. Simply from a
practical standpoint, it may be more workable to reserve such precise
determinations for watershed-specific decision-making. Therefore, in
highlighting the issue of greater specificity, EPA is suggesting that
one, but perhaps not the only, way to resolve this issue is to mandate
much greater specificity in a State or Tribal use classification
structure.
Obviously, there is a need for designated use descriptions in State
and Tribal regulation to be defined, at a minimum, with sufficient
specificity to ensure existing and potential uses will be protected
and/or attained. The difficulty is in striking a balance between
specificity sufficient to ensure uses are appropriately protected and
flexibility needed to allow efficient widespread application of a
classification system to all State or Tribal waters. A question has
been raised about, and EPA is considering, whether or not the current
regulation and guidance provide the framework needed to strike the
appropriate balance and the guidance on when and how to refine uses.
Aquatic Life
An issue related to the manner in which States and Tribes define
designated aquatic life uses is the occasional confusion expressed
between the actual intent of the CWA section 101(a)(2) interim goals
and the ``fishable/swimmable'' short hand expression often used to
describe those interim goals. EPA acknowledges that the phrase
``fishable/swimmable'' does not fully describe the intent and scope of
the CWA section 101(a)(2) interim goals. The confusion over the
expression ``fishable'' often surfaces where there is an action aimed
at removing an aquatic life use from a particular water body where
there are no sport or commercial fisheries. In these instances, an
argument is often made that the water body does not meet the
``fishable'' intent of the section 101(a)(2) interim goals because the
water body naturally supports only ``minnows'' and/or aquatic
invertebrates. EPA believes this is an unacceptable argument for
removing an aquatic life designated use or excluding an aquatic life
designated use. As explained in EPA's Questions and Answers on
Antidegradation (USEPA, 1985, p. 3), the Agency considers the
protection afforded by standards to focus on an appropriately
representative aquatic community whether or not that community includes
sport or commercial fish:
The fact that sport or commercial fish are not present does not
mean that the water may not be supporting an aquatic life protection
function. An existing aquatic community composed entirely of
invertebrates and plants, such as may be found in a pristine
tributary alpine stream, should be protected whether or not such a
stream supports a fishery. Even though the shorthand expression
``fishable/swimmable'' is often used, the actual objective of the
Act is to restore the chemical, physical and biological integrity of
our Nation's waters (Section 101(a)). The term ``aquatic life''
would more accurately reflect the protection of the aquatic
community that was intended in Section 101(a)(2) of the Act.
Thus, EPA's current interpretation of the regulation means that the
Agency will not approve State or Tribal action to exclude aquatic life
protection based on a conclusion that a water body does not support a
``fishery'', implying a sport or commercial fishery. EPA's current
thinking is that it would improve the regulatory text to reflect this
interpretation explicitly.
More specific to this discussion of refined designated uses is the
question of whether or not the Agency should mandate that a minimum
``aquatic life'' use sub-category or sub-categories be included in all
State or Tribal designated use classification systems to ensure
appropriate protection of waters
[[Page 36751]]
which do not support commercial or sport fisheries (or any fish).
Refined Designated Uses and Use Attainability Requirements
There is one additional issue related to the refined designated use
discussion that should be addressed. A question has been raised about
the applicability of the use attainability requirements when
establishing refined designated uses (with particular emphasis of
aquatic life uses). The question raised is: since refined designated
uses may be less inclusive than broad designations, will EPA consider
development of a more refined use description to be a change in use
subject to the use attainability requirements? Under current
regulation, the combination of a new use sub-category and less
stringent criteria triggers the use attainability requirements in
Sec. 131.10 of the Federal regulation (see Sec. 131.10(j)(2)). However,
it is possible that under certain circumstances, this requirement could
be modified.
Such a modification would focus on the kind of information that
should accompany any refined use classification based on a more precise
biological description, whether or not formal use attainability
assessment requirements apply. Essentially, there are two issues to be
addressed: (1) does the refined description of the aquatic community
reflect the reference condition (i.e., natural states) for the kinds of
waters to which the new classification is to be applied? and (2) are
any newly proposed criteria scientifically defensible? These are basic
questions which would have to be addressed whether or not the use
attainability requirements were invoked. As a result, a proposal to
refine use categories will have to be accompanied by a rationale
explaining how it was determined that the proposed biological
description appropriately reflects the potential for waters to which
the new sub-classification is to be applied. If warranted, this refined
description can then serve as the basis for deriving defensible and
appropriate criteria specific to the new sub-classification.
Request for Comment Refining Use Designations
EPA seeks comment on the following questions:
1. The current regulation is not specific about the level of
precision States or Tribes must achieve in designating uses. The
regulation allows for subcategories of uses, but does not mandate such
an approach. Should the regulation be revised to promote or require
greater specificity in designated uses, particularly for aquatic life
uses, to support watershed-specific decision-making such as is
anticipated in implementing watershed or place-based initiatives?
2. Where a State or Tribe utilizes broadly-defined designated uses,
could the desired level of specificity be adequately addressed in State
or Tribal standards that clearly articulate the intent of the
designated uses as they would apply to specific waters of the State or
Tribe?
3. If EPA were to specify a required level of precision in
establishing use categories, what factors should be considered in
prescribing a level of specificity? That is, what factors should be
considered in striking a balance between specificity sufficient to
ensure uses are afforded an appropriate level of protection and
flexibility/efficiency needed to allow widespread application of the
classification system?
4. At a minimum, should the regulation require that State and
Tribal aquatic life use categories include a sub-category or sub-
categories that may be assigned to protect aquatic communities that do
not include a ``fishery''? Alternatively, should the regulation
explicitly reflect EPA's current interpretation of the regulations to
the effect that State and Tribal aquatic life classification systems
protect a range of aquatic communities whether or not there are sport
or commercial fish (or any fish) present?
5. Should the use attainability requirements in 131.10(j)(2) be
modified to recognize situations where scientifically defensible less
stringent criteria may be appropriate for refined uses which reflect
the reference condition for particular waters?
3. Existing Uses
a. Protection of Existing Uses. The requirement to protect existing
uses is addressed in two places in the current regulation--Section
131.10, designation of uses and Section 131.12, antidegradation. (see
discussion of antidegradation, ``tier 1'', in section III.D of this
document) As discussed in the background section above, the regulation
defines ``existing uses'' as ``those uses actually attained in the
water body on or after November 28, 1975, whether or not they are
included in the water quality standards.'' (40 CFR 131.3(e)) As a
result, the focus of existing uses, is on the past or present condition
of the water body. Furthermore, by establishing requirements
prohibiting the removal of existing uses and ensuring those uses will
be appropriately recognized in State and Tribal water quality
standards, the current regulation ensures that the better of the past
or present condition, at a minimum, will be maintained and protected.
Determining whether or not an existing use has occurred in the past or
is currently in place is not always a straightforward task, however,
and over the years, a number of questions have been raised about
exactly what the ``existing use'' provisions in 131.10 require. These
questions generally fall into two categories: (1) what is the link
between existing uses and the State or Tribal use classification
system? and (2) what is the relationship between existing uses,
existing water quality and potential uses, i.e. uses that may be
attainable in the water body whether or not those uses are presently
designated for the water body or are presently being attained?
The first question addresses the relationship between the existing
use protection provisions in Section 131.10 and State or Tribal use
classification systems. There appears to be some confusion on this
point. The confusion seems to center on what may appear to be
conflicting mandates--protect what is there and allow no further
erosion of water quality, and appropriately designate the existing use
in regulation using the established classification system. The existing
use definition and the requirement that existing uses be protected
suggests to some that the description of existing uses is constrained
by the way in which a State or Tribe has described its designated uses
in its classification system. That is, they argue that an existing use,
to be adequately protected, needs to fit into one of the categories or
sub-categories established in State or Tribal regulation, and as a
result, a decision about whether or not a use is ``existing'' is
likewise constrained by the use descriptions and criteria established
in that classification system.
For purposes of Section 131.10, this is generally the case. Again,
this Section of the Federal regulation establishes two requirements
with respect to existing use protection: (1) a prohibition against
removal of a designated use where that use is determined to be an
existing use, and (2) a requirement that existing uses be protected by
State or Tribal regulation. To ensure a workable process, EPA
interprets Section 131.10 as necessarily recognizing a linkage between
the existing use protection provisions and the established State or
Tribal use classification system. This interpretation of the regulatory
framework, however, also presumes a responsibility on the part of a
State or Tribe to establish a classification system that is
sufficiently flexible and/or
[[Page 36752]]
encompassing to assure an appropriate level of protection for the
anticipated range of existing uses (see discussion on refined
designated uses in this chapter).
As explained earlier in the discussion on refined designated uses,
a variety of use classification systems has evolved and become
established in State and Tribal programs. Although there are likely
some advantages to a more refined use classification system when it
comes to protecting existing uses (more precise categories in which to
fit the existing use), such a system may not be necessary as long as
the State or Tribal standards clearly articulate the intended and
appropriate level of protection for existing uses (again, see
discussion of refined designated uses). The following example
illustrates the point. An acid bog is a water body type which may be
fairly widespread but which, as a classification type, may not appear
in many State or Tribal standards. Where the aquatic characteristics of
an acid bog are discovered to constitute an existing use, a State or
Tribe could: (1) establish a classification type and criteria for acid
bogs to ensure appropriate protection by way of a specific designation,
or (2) classify the bog within the existing, general classification
system, e.g., warm water aquatic life, and adopt any needed site-
specific criteria to ensure the existing nature and quality of this
specific water resource is protected. Either approach can result in an
appropriate level of protection and there may not be a need for States
or Tribes to include an ``acid bog'' water body type in their
classification system. Under either approach the standards must
articulate clearly the intended and appropriate level of protection,
ensuring protection of the existing use.
It is also important to remember that the existing use provisions
in both Secs. 131.10 and 131.12 must be considered together. The
classification requirements in Sec. 131.10 ensure that all existing
uses will be recognized and protected through appropriate
classification of those water bodies in the standards (and/or
application of appropriate site-specific criteria where the existing
classification system is broadly constructed). The antidegradation-
based existing use protection provision guarantees that individual
activities on individual water bodies will be examined to ensure those
activities will not eliminate existing uses, whether or not those uses
are currently recognized in the State or Tribal standards. The
antidegradation provisions, through the general requirement that
existing uses be protected, ensure immediate protection from specific
activities which may threaten the existing use, and the classification
requirements ensure recognition and longer-term protection from any
present or future stressors through specific designation in the
standards. Both these provisions apply and should not be considered in
isolation. Together they constitute the existing use protection
requirements, ensuring the existing uses and water quality to support
those uses are maintained and protected.
The second question addresses the relationship between existing
uses, existing water quality and potential uses. The Agency's guidance,
Questions and Answers on Antidegradation, August, 1985 (Notice of
Availability, 50 FR 34546, August 26, 1985 [included as appendices to
Water Quality Standards Handbook, cited above]) addresses this issue,
in part. The answer to ``question 7'' states: ``an existing use can be
established by demonstrating that fishing, swimming, or other uses have
actually occurred since November 28, 1975, or that the water quality is
suitable to allow such uses to occur (unless there are physical
problems which prevent the use regardless of water quality).'' Using an
example of a healthy shellfish community which is not currently being
harvested, the answer goes on to explain that the existence of a use
(past or present) is not dependent solely upon a demonstration that the
use is being satisfied in a functional sense (i.e., in this case, the
shellfish harvested). In this example, ``shellfish harvesting'' is
considered an existing use, even though there is presently no
harvesting underway, because the water quality and habitat support a
healthy shellfish community suitable for harvesting. The answer further
explains that to assume otherwise ``* * *would be to say that the only
time an aquatic protection use `exists' is if someone succeeds in
catching fish.'' As illustrated in this example, the existing use
question must address both the current or past functional use and the
current or past (since November 28, 1975) water quality, and the intent
of the regulation is to ensure the existing use and the water quality
necessary to support that use are maintained and protected. Thus, in
this example, the shellfish harvesting use is to be protected by
designated uses in water quality standards.
The shellfish example is a good one in that it clearly illustrates
EPA's position that an existing use finding can be made either where
the use is or has been ``actually attained'' or where the water quality
necessary to support the use is in place even if the use, itself, is
not currently established, as long as other site-specific factors, for
example physical problems like flow or substrate, would not, despite
the suitable water quality, prevent attainment of the use. The ``other
factors'' caution is important in understanding EPA's position on
existing uses. In making an existing use determination, there is a link
between the use and water quality. To be considered an existing use,
the use must have been actually attained in the past, is now attained
or water quality is sufficient to support the use. However, for some
sites, water quality, alone, may be an insufficient basis for making an
existing use finding if there are other factors that would prohibit the
use from taking place regardless of the quality of the water at a site.
In the shellfish example, the necessary water quality is present, and
there are no obvious limiting factors which would prohibit present or
future shellfish harvesting.
Although this example is useful in illustrating important
principles in implementing existing use protection requirements, it is
a rather straightforward example. An appropriate resolution of the
existing/designated use issue may be somewhat less clear-cut where
either the existing water quality or the existing use is marginal
(i.e., it is difficult to determine whether or not the use is actually
attained, or whether or not there are factors, other than water
quality, that could prohibit the use). It is in addressing these
situations that questions have been raised about what the current
regulation requires. A principal difficulty in addressing these
questions may lie in resolving the linkage between the present and past
conditions protected by the ``existing uses'' provisions and the
attainable or potential condition protected by ``designated uses''
provisions. It may be useful to evaluate this issue by considering the
link between existing and designated uses established in the current
regulation.
Obviously, any decision about whether or not a use is an ``existing
use'' must be a water body-specific determination. The existing use
determination is, therefore, site-specific, and decisions should
consider water quality and other limiting factors such as the physical
habitat specific to a particular water body. A few examples may help
illustrate the issue. A somewhat common existing use question applies
to primary contact recreation: if a few people on a few occasions
``swim'' in a water body that does not have the quality or physical
characteristics to support swimming, is this an existing use, even if
the water body is posted ``no swimming'' due to
[[Page 36753]]
bacterial contamination and lacks the physical features to actually
support swimming? The straightforward answer to this question is that
``swimming'' is not an existing use because the present (or past)
condition does not support that use. This conclusion is based on the
very limited actual ``use'' and, more importantly, the lack of suitable
water quality and physical characteristics that would support a
recreational swimming use now or in the future (as determined by the
water quality requirements and recreational swimming considerations,
including safety considerations, in the State or Tribal classification
system for primary contact recreation).
A question has been raised as to how to interpret the regulation in
the context of this example. One could determine that because the water
body is not suitable for swimming, and has not been since 1975, primary
contact recreation is not an existing use. Alternatively, one could
determine primary contact recreation to be an existing use because the
water body was actually used for swimming, even though the use was
occasional and water quality and physical characteristics were not
acceptable to support such a use. EPA believes the first alternative is
the better interpretation of Agency regulations and guidance in this
example, because the use is not established and the water quality and
other factors would appear to prohibit actually attaining a
recreational swimming use.
Stating that this is an appropriate interpretation of the
regulation means that EPA would not object if a State or Tribe reached
a conclusion, in a similar case, that this was not an existing use. As
noted above, however, existing use decisions are very site-specific,
and it is possible that, on a specific water body under similar
circumstances, a different conclusion could be reached by a State or
Tribe based on public comment at a hearing and a decision to take a
protective approach to the incidental use for that specific resource.
The Federal requirements do not prohibit a State or Tribe from taking a
more protective approach than would be required by the water quality
standards regulation.
Although, in the above example, a State or Tribe could conclude
that primary contact recreation is not an existing use, it may well be
an attainable use that must be protected as a designated use by the
State's or Tribe's water quality standards. This finding would depend
on whether the physical condition of the water body is suitable for
swimming and whether the water quality problems limiting the use are
controllable. (See 40 CFR 131.10(j) and discussion on use attainability
analysis below). The point is that, although the existing use
provisions most directly address past or present conditions, decisions
about existing uses generally are not made in isolation. With respect
to uses contained in CWA Section 101(a)(2), the regulation links
existing and designated uses, and it may be useful to view these
provisions as a continuum in examining the broader question of use
protection.
Some States and Tribes have recognized that continuum in developing
use attainability guidance for recreational uses which includes
questions about the actual use, existing water quality, water quality
potential, recreational facilities, location, safety considerations,
physical conditions of the water body, and access
Note: access here means restricted access, as in fenced
property; access is not intended to suggest the ``remoteness'' of
the water body; in EPA's view, remoteness is not a valid basis for
an attainability decision on recreation.
When all of these factors are considered, the adopted water quality
standards are consistent with both the existing and designated use
provisions. For example, suppose a city has created a greenway along a
stream that receives wastewater effluent upstream of the greenway and
has posted ``no swimming'' signs. The greenway attracts children
leading to the inevitable ``unauthorized'' swimming. If the physical
condition of the stream is suitable for swimming, the swimming occurs
on a frequent basis and the greenway provides recreational facilities
and access, the only factor limiting the use may be a water quality
problem that in the judgement of the State or Tribe can be controlled
to achieve the primary contact use. The linkage between existing and
designated uses encourages the evaluation of this full suite of factors
in making a decision about whether or not primary contact recreation
should be protected.
A similar existing use question is often raised for aquatic life
uses where the existing aquatic community is impaired as a result of
marginal water quality. A common example in the western part of the
country is a mountain stream impaired by historic hard rock mining
(with the impacts occurring well before November 28, 1975). Although
the physical condition of the stream may represent ideal trout habitat,
the trout population may be severely limited, in poor condition or
absent as a result of the toxic effects of metals. In its
classification system, however, a State or Tribe may describe and
designate this type of stream as a ``salmonid spawning'' use based on
its physical habitat and potential. For streams such as these, where a
few adult trout are present but there is no evidence of younger age
classes, the question is asked--is this an existing ``salmonid
spawning'' use?
Again, the appropriate answer, based on EPA regulations and
guidance, is that this is not an existing use (although it may
nonetheless be an appropriate designated use if it has the potential to
support salmonid spawning). The current use, matching the
classification description, is absent, and the limiting water quality
problems have been in existence prior to November 28, 1975. (This does
not mean, necessarily, there is not some existing aquatic life use
which would then serve as the regulatory ``floor'' for this water body;
see the ``limited'' aquatic life use discussion in the use
attainability analysis discussion in this section below and the ``tier
1'' discussion in the antidegradation section, III. D) As in the
``swimming'' example, however, there can be a gradation of conditions,
and occasionally it may be difficult to draw a bright line and
conclude, with confidence, that this is where the existing use begins.
In situations similar to this impaired stream example, where the
existing water quality problems are considered controllable by the
State or Tribe, arguments have been made on both sides of the existing
use issue: the salmonid spawning use is not existing, or the salmonid
spawning use is in place, albeit currently at an impaired level.
Disputes about the correct interpretation of Agency guidance become
even more difficult to resolve where the existing impacts to water
quality are not as great as those in the above example. Often streams
impacted by historical mining, such as the one described above, are
headwater streams. As the water moves downstream, clean water
tributaries reduce the effect of the metals contamination, and fish, in
number, begin to move into these ``improved'' waters. Nevertheless,
many such streams would be considered impaired when compared to
unaffected, similar waters (reference streams). And, despite supporting
``fairly good numbers'' of trout, the existing water quality in such
streams often exceeds the chronic and, occasionally, acute standards
for metals. In situations such as these, States and Tribes have had
difficulty in reaching conclusions about whether or not an existing
use, matching the classification, is in place. Because States and
Tribes may evaluate existing uses when they are designating uses,
threshold existing use
[[Page 36754]]
determinations may lead to questions about the potential for the water
body and the appropriate designated uses for it.
EPA's current interpretation is that the existing use should be
identified either where the use has taken place or the water quality
sufficient to support the use has existed since November 28, 1975, or
both. That is to say, State and Tribal existing use decisions can be
based on a finding that the use, as defined in the classification
system, and/or the water quality needed to support the use is in place
(and there are no other factors that would prohibit actually attaining
the use). This interpretation does not fully address the issue of
partially impaired uses. Thus, a fuller explanation may be needed in
the regulation or policy of how that interpretation is applied where
the use or the water quality may be somewhat impaired. EPA is
considering whether changes to the regulation or additional guidance is
needed to explain the Agency's position and to offer direction in
making such determinations.
Request for Comment on Existing Uses
EPA seeks comment on the following questions:
1. Does EPA need to further clarify the existing use protection
provisions in Sec. 131.10, more clearly explaining that existing uses
are defined by the uses made of water bodies and existing water
quality, where that quality is or was sufficient to allow the use to
occur (and there are no other limiting factors)? If so, will the
clarification require a regulatory amendment or can the needed
clarification be accomplished in Agency policy or guidance?
2. Does EPA need to expand its guidance to explain how the current
regulation addresses existing use decisions where there is some
semblance of a use even though the water quality is insufficient to
support the use in, for example a safe or healthful manner? Should this
additional guidance clarify the linkage between existing and designated
uses?
3. Should the regulatory definition of ``existing use'' at 40 CFR
131.3(e) be modified? If so, how?
4. Use Attainability.
a. Attainability of Uses. States and Tribes may remove a designated
use, that is not an existing use, if they can demonstrate that
attaining the designated use is infeasible. (40 CFR 131.10(g)) The
current regulation identifies the factors that must be considered in
making such a demonstration. As explained in the regulation, existing
uses, by definition, are attainable and must be protected by designated
uses in water quality standards (40 CFR 131.10(h)(1), 131.10(i) and
131.12(a)(1)). Further, at a minimum, uses are considered attainable if
they can be achieved by implementing effluent limits required under
Sections 301(b) and 306 of the Clean Water Act (Act) and by
implementing cost-effective and reasonable best management practices
(BMPs) for nonpoint source control. (40 CFR 131.10(h)(2)).
These existing uses, technology and BMP provisions establish the
basic regulatory threshold test for what the attainable use of a water
body is and thus what the minimum use designation for the particular
water body must be. Where either the use is existing or the use can be
attained through implementation of Clean Water Act technology
requirements and/or implementation of applicable State requirements
regarding BMPs for nonpoint source control, 40 CFR 131.10(h)
establishes that the use is attainable and must be designated. Once a
use is designated, it is presumed to be attainable and may not be
removed (downgraded) unless the State or Tribe can demonstrate that
attaining the designated use is not feasible based on one of the six
use removal criteria (40 CFR 131.10(g)). Therefore, uses are considered
attainable if: (1) the use is existing; (2) the use can be attained
through application of CWA technology requirements and/or State or
Tribe required BMPs; or, (3) none of the use removal criteria is
satisfied. EPA has in the past recommended that these use removal
criteria referenced under number 3 above, serve as additional tests,
over and above numbers 1 and 2 above, for determining when a use is
attainable. Clearly these use removal criteria (131.10(g)) are designed
to determine whether a use is attainable and therefore can serve that
purpose equally effectively when considering whether to remove a
designated use (the situation where they are clearly required to be
used) and when considering whether a use is attainable and should be
designated. The discussion below on use attainability analysis (UAA)
and non section 101(a)(2) uses further discusses the relationship
between designation of attainable uses, UAAs, and the analysis required
to justify use removal. That discussion solicits comment on whether the
use removal criteria at Sec. 131.10(g), in addition to being the
regulatory justifications for use removal, should, consistent with
EPA's interpretation of the regulation, be included in the basic
elements of a UAA.
Despite what EPA believes are fairly clear guidelines in the
current regulation and guidance, questions have been raised about EPA's
minimum attainability requirements. The Agency's current thinking is
that basic attainability requirements, the methods for demonstrating
attainability, the circumstances under which attainability analysis
must be done, and what that analysis must consist of should be
clarified in the regulation.
b. Removal of Designated Uses. The regulation (at 40 CFR 131.10(g))
specifies that States and Tribes may remove a designated use which is
not an existing use if attainment of a use is not feasible due to the
following:
(1) Naturally occurring pollutant concentrations prevent the
attainment of a use; or,
(2) Natural, ephemeral, intermittent, or low flow conditions or
water levels prevent the attainment of the use, unless these conditions
may be compensated for by the discharge of sufficient volume of
effluent discharges without violating State or Tribal water
conservation requirements to enable uses to be met; or,
(3) Human caused conditions or sources of pollution prevent the
attainment of the use and cannot be remedied or would cause more
environmental damage to correct than to leave in place; or;
(4) Dams, diversions or other types of hydrological modifications
preclude the attainment of the use, and it is not feasible to restore
the water body to its original condition or operate such modification
in a way that would result in the attainment of a use; or,
(5) Physical conditions related to the natural features of the
water body, such as the lack of a proper substrate, cover, flow, depth,
pools, riffles, and the like, unrelated to water quality, preclude
attainment of aquatic life protection uses; or,
(6) Controls more stringent than those required by Sections 301(b)
and 306 of the Act would result in substantial and widespread economic
and social impact.
The use removal criteria were included in the regulation to address
those circumstances where the attainability of certain uses would be
precluded by conditions over which the water quality protection
provisions in the regulation had little or no control. The
uncontrollable conditions considered most likely to limit attainability
were: natural water quality or habitat limitations, irretrievable
human-caused contamination or conditions, or insupportable economic and
social costs. These general
[[Page 36755]]
conditions, then, formed the basis for the six use removal criteria.
Although EPA believes the use removal criteria have functioned
reasonably well, the growing number and reoccurring nature of the
questions raised about these criteria have convinced EPA of the need to
review this central element of the program.
Some have argued that the six criteria and their interpretation are
overly stringent, making any proposal to remove a designated use futile
even where a use was ``mistakenly'' designated. Others argue that the
use removal criteria and their interpretation are overly generous,
granting the possibility of use removal where the principal stressor is
a condition which should not be immune from the water quality
protection provisions in the federal regulation (operation of dams is
one example used in arguing this position). Others complain that there
seems to be no national consistency in the way the use removal criteria
are interpreted by EPA, the States or the Tribes. And, finally,
questions also have been raised about whether or not the criteria
adequately address or apply to all uses equally. The key to appropriate
application of the use removal criteria is to focus on whether or not a
condition, at a specific site, would preclude attaining a designated
use. A decision on this question is not always straightforward however,
and as a result, there are questions about the application of the use
removal criteria. A few examples may help the discussion.
Criterion number 1 allows removal of a designated use where
``naturally occurring pollutant concentrations prevent attainment of
the use.'' A reoccurring question about this provision is: under what
circumstances should ``naturally occurring pollutant concentrations''
be the justification for use removal versus the basis for calculating
site-specific criteria, acknowledging that the natural condition
defines the existing use? Often, the numerical criteria assigned to the
designated use are the initial benchmark for estimating whether or not
a designated use will be attained. In this approach, a comparison of
the natural condition with the numerical criteria is used in the
evaluation of attainability. Where such an analysis demonstrates
clearly that the naturally occurring pollutant concentrations would
preclude the designated use, the use may be removed. There are,
however, examples of situations where statewide or national criteria
for one or more contaminants are exceeded, and yet the available
information on the overall condition of the water indicate the use is
supported. This situation is most common for aquatic life uses where
local populations of aquatic organisms may have acclimated to natural
conditions outside the estimated ``normal'' tolerance range, where
species on the edge of their distribution are reproducing but are
physiologically stressed or where broadly derived criteria may not be
appropriate for the particular aquatic community at that site. In such
a situation, the observed condition of the resource obviously will take
precedence over the predicted condition, and the natural water quality
will form the basis for site-specific criteria since the use is clearly
not precluded. Again, the key to answering the use removal question is
to determine whether or not ``natural conditions'' preclude attainment
of the use, and because of the site-specific circumstances discussed
above, answering this question involves more than a simple comparison
of numeric criteria with the natural condition.
Criterion number 2 allows removal of a designated use where
natural, ephemeral, intermittent, or low flow conditions would preclude
the use unless these conditions may be compensated for by the discharge
of sufficient volume of effluent discharges without violating State or
Tribal water conservation requirements to enable uses to be met
(emphasis added). Questions have been raised about exactly what the
above italicized language means. EPA's interpretation of this phrase is
that, where an effluent discharge creates an essentially perennial flow
for what naturally would be ephemeral or intermittent waters, the
resulting aquatic community is to be protected. EPA's current thinking
is that in situations such as these, the second criterion for use
removal means that a State or Tribe cannot remove a use of a water body
where the augmented flow supports an aquatic life use.
Criterion number 4 allows removal of a use where dams, diversions
or other types of hydrological modifications preclude the attainment of
the use, and it is not feasible to restore the water body to its
original condition or operate such modification in a way that would
result in the attainment of a use. As indicated above, some have argued
that operation of dams is an inappropriate basis for concluding that
Section 101(a)(2) uses are not attainable, and they have suggested this
criterion be removed from the regulation. In arguing this position,
these commenters have pointed to the 1986 amendments to the Federal
Power Act (Electric Consumer's Protection Act, or ECPA) and the
legislative history of these amendments as an indication of Congress'
intent to give equal priority to protecting and restoring fish and
wildlife habitat even where dams exist. Specifically, the ECPA states:
* * *In deciding whether to issue any license the
{Federal Energy Regulatory Commission}, in addition to
the power and development purposes for which licenses are issued,
shall give equal consideration to the purposes of energy
conservation, the protection, mitigation of damages to, and
enhancement of fish and wildlife (including related spawning grounds
and habitat), the protection of recreational opportunities, and the
preservation of other aspects of environmental quality. (ECPA
amending the Federal Power Act, Section 4(e), 16 U.S.C. Section
797(e))
The legislative history, these commenters believe, provides a
particularly clear indication of congressional intent to protect and
restore aquatic life uses. They specifically point to that part of the
record which states that no one ``expect[s] `business as usual,' '' but
rather the expectation is that:
[P]rojects licensed years earlier must undergo the scrutiny of
today's values as provided in this law and other environmental laws
applicable to such projects. If nonpower values cannot be adequately
protected, FERC should exercise its authority to restrict or,
particularly in the case of original licenses, even deny a license
on a waterway. (H.R. Rep. No. 99-934, 99th Cong., 2d Sess. (1986) at
22)
Groups arguing for removal of criterion 4 use the amendments to the
Federal Power Act as an example of the recognition being given today's
environmental values and the importance of restoring and enhancing the
aquatic habitats and recreational uses of water resources. They
maintain that ``...the Water Quality Rule should be updated to
recognize that aquatic and recreational uses can not be removed based
simply on the existence of a dam.'' EPA's current thinking is that the
above rationale and legislative history raise a serious question about
whether the existence of a dam and the infeasibility of operating that
dam in a way that will result in attaining the designated use, measured
against today's values, is sufficient reason to remove a designated
use. EPA is interested in commenters views on this issue.
Criterion number 5 allows removal of a designated use where
physical conditions related to the natural features of the water body,
such as the lack of proper substrate, cover, flow, depth, pools,
riffles, and the like, unrelated to water quality, preclude attainment
of
[[Page 36756]]
aquatic life protection uses. Notwithstanding the reference to aquatic
life uses in 131.10(g)(5), some have argued that recreational uses,
especially swimming uses, might also be limited by physical factors
(especially where safety is an issue), and they have asked whether or
not the physical factors consideration could be applied to evaluations
of recreational use attainability. As now written, the regulatory
language would not allow consideration of physical factors, alone, as
the basis for removing a designated recreational use. In the preamble
to the 1983 regulation, EPA explained that, while the Agency recognized
that physical factors also affect recreational uses, States, and now
Tribes, would need to give consideration to incidental uses of the
water body even though it may not make sense to encourage use of a
stream for swimming because of the flow, depth or velocity of the
water. Instead, the preamble discussion explained that based on prudent
public health considerations, the use protection question was not to be
judged wholly on an analysis of the water body's suitability for
swimming but rather on whether or not swimming would actually occur.
EPA's current thinking is that physical factors, alone, would not be
sufficient justification for removing or failing to designate a primary
contact recreation use.
EPA's suggested approach to the recreational use question has been
for States and Tribes to look at a suite of factors such as, the actual
use, existing water quality, water quality potential, access,
recreational facilities, location, safety considerations, and physical
conditions of the water body in making any use attainability decision.
The guidance suggests that any one of these factors, alone, may not be
sufficient to conclude that designation of the use is not warranted.
Nevertheless, there clearly are situations such as high flows caused by
storm events where the physical conditions of a water body would make
swimming, if not impossible, extremely dangerous. It is in addressing
situations such as these that questions have been raised about the
applicability of physical factors to the recreational use issue. The
question is sometimes posed in terms of whether or not a State or Tribe
would incur some liability by designating or continuing to designate
such waters as swimmable. They argue that a reasonable, common sense
approach is to acknowledge that there are certain waters for which
primary contact recreation is not an attainable use solely because of
the physical condition of the water. EPA is, therefore, considering
whether the regulation or Agency guidance should be amended to allow
consideration of physical factors, alone, as the basis for removing or
not designating primary contact recreational uses.
The above discussion is about EPA's interpretation of the
conditions that would have to be satisfied to either remove or not
designate recreational uses. As explained earlier in this section,
satisfying those conditions gives a State or Tribe the option of either
removing or not designating the use. It does not, however, create an
obligation. A specific example may help. A western State was concerned,
partly for liability reasons, about designating swimming uses for a
number of waters where the physical conditions and other factors made
swimming, if it did occur, unwise. Although available information
indicated the actual swimming use was limited or nonexistent, the State
also wanted to ensure protection of that use, based on public health
considerations, should it occur. The issue for the State was striking
the appropriate balance between the two concerns: the possibility of
inadvertently encouraging swimming where it should not occur because of
safety considerations and protecting that use if it did occur. To
resolve this issue, the State designated these waters for secondary
contact recreation but assigned primary contact recreation
bacteriological criteria to provide an appropriate level of protection
should swimming occur, however unlikely. In this way, the State felt it
did not inappropriately encourage swimming in these waters, but if
swimming did occur, the required water quality would provide an
appropriate level of protection. This is an approach to the
``incidental use'' issue, discussed in the existing use section of this
chapter, that, while acknowledging uncertainty, errs on the side of
protectiveness.
Consistency
EPA has provided guidance on implementing the requirements in
Sec. 131.10(g). Although EPA believes the guidance has been fairly
comprehensive and has functioned reasonably well, the growing number
and recurring nature of the questions raised about implementation of
the use removal criteria have convinced EPA to solicit comments on the
need for additional guidance or regulatory changes to ensure
appropriate and consistent application of the use removal criteria.
As indicated in the introduction to this discussion, one of the
reoccurring concerns about implementation of Secs. 131.10(j) and
131.10(g) with respect to designating or removing uses, is that to
some, there are instances of inconsistency in the way the
Sec. 131.10(g)(1)-(6) criteria are interpreted by EPA, the States or
the Tribes. One example that has been cited is that the application of
the fish consumption use is dissimilar in different regions of the
country. In one area of the country, some maintain, the fish
consumption use is applied to all waters assigned any aquatic life use
without regard to whether or not there is a credible exposure pathway
to humans by way of contaminated fish. In other areas of the country,
the application of the fish consumption use allows consideration of
occurrence, size and species of fish present and evidence that fishing
actually occurs as a basis for concluding that there is a potential
exposure pathway and the use should be designated. An associated
consistency issue has to do with the manner in which the terms in
Sec. 131.10(g) are interpreted. An example is the term ``feasible'' in
criterion number 4. Feasibility could be based on technical
considerations, such as the ability to operate an impoundment in an
efficient manner that does not degrade water quality, as EPA intended
when it originally wrote the regulation. Alternatively, some have
suggested that feasibility could be based on economic considerations or
a balanced consideration of cost and technology (EPA's current thinking
is that the term ``feasible'' in use removal criterion number 4,
regarding the operation of dams should continue to refer to technical
feasibility and not to economic feasibility. Criterion number 6, not
number 4, is the appropriate avenue to address economic feasibility of
attaining the designated use because it establishes an appropriate test
of economic infeasibleness.)
EPA's view is that the use removal criteria should be clear and
consistently interpreted. Questions and/or positions such as those
described above suggest there may be a need for additional guidance on
or interpretation of Sec. 131.10(g) to ensure the Sec. 131.10(g)
criteria are consistently interpreted and applied, and to address
whether review under Sec. 131.10(g) could be done for categories of
sources.
c. Use Attainability Analysis. A use attainability analysis (UAA)
is a structured scientific assessment of the factors affecting the
attainment of uses specified in section 101(a)(2) of the Act (the
``fishable/swimmable'' uses). The factors to be considered in such an
analysis include the physical, chemical, biological, and economic use
removal
[[Page 36757]]
criteria described in the current regulation (40 CFR 131.10(g)(1)-(6)).
The current regulation (40 CFR 131.10(j)) establishes the requirement
that States and Tribes conduct a UAA when designating uses that do not
include the section 101(a)(2) uses, removing section 101(a)(2) uses, or
designating new subcategories of section 101(a)(2) uses that require
less stringent criteria.
New Information for Waters Without Section 101(a)(2) Use Designations
The current regulation (Sec. 131.20(a)) specifically requires the
re-examination of water bodies with less than Section 101(a)(2) use
designations every three years to determine if new information has
become available. If new information indicates that a use is
attainable, the State or Tribe is to revise the use accordingly. EPA
interprets the current regulation as requiring review of past UAA-based
use designation decisions when there is new information that could have
a bearing on that use designation decision.
The 1983 preamble to the regulation explained that a State or Tribe
need only conduct a UAA once for a given water body. The preamble went
on to explain, however, that where the UAA is used as justification for
removing a section 101(a)(2) use or failing to designate a section
101(a)(2) use, the State is required to review the basis for that
decision in subsequent triennial reviews to determine whether or not
the circumstances have changed in a way that would alter the original
decision. EPA recognizes that the requirement to review new information
about past UAA-based use designation decisions, because it creates a
demand for further analysis of the decision by the State or Tribe, can
serve to discourage States and Tribes from generating new information.
EPA's current thinking is that interested parties should be encouraged
to generate and consider relevant information that could have a bearing
on the use designation decision for a particular water and that the
trigger for reviewing past use designation decisions should be clear.
In addition, EPA is interested in comments on whether there should be
some definable burden placed on the State or Tribe to actively seek
information for such waters. The Agency may need to be more specific in
requiring that States and Tribes specify the procedures they will use
in identifying water bodies where ``new information'' has become
available and ensuring new information is generated where appropriate.
UAAs and Non Section 101(a)(2) Uses
The current regulation indicates that the UAA requirements apply to
uses specified in Section 101(a)(2) of the Act. The regulation at 40
CFR 131.10(j) specifically requires that a State or Tribe conduct a UAA
where: ``(1) the State [or Tribe] designates or has designated uses
that do not include the uses specified in Section 101(a)(2) of the Act,
or (2) the State [or Tribe] wishes to remove a designated use that is
specified in Section 101(a)(2) of the Act or to adopt subcategories of
uses specified in Section 101(a)(2) of the Act which require less
stringent criteria.'' Although the regulation at 40 CFR 131.10(g) has
always provided that States and Tribes may not remove a designated use
unless they can demonstrate that attaining the use is not feasible, the
regulatory language does not expressly require the State or Tribe to
conduct a UAA as defined in 40 CFR 131.10(j) before a use not
referenced in section 101(a)(2) may be removed. As a result, some have
questioned whether or not the UAA requirements actually apply to uses
other than those referenced in Section 101(a)(2), such as water supply
or agriculture. EPA's position on this issue is that, while the
analysis to downgrade a use not included in CWA section 101(a)(2) is
not expressly referenced in Sec. 131.10(j), 40 CFR 131.10(g) of its own
terms requires the State or Tribe to document whether any use being
considered for removal is attainable under the six criteria outlined in
that section. Where such a use is shown to be attainable, it may not be
removed (downgraded). In practice, EPA believes there is no cognizable
difference between these two analyses. EPA is thus considering whether
it should combine these elements of 40 CFR 131.10(g) and 131.10(j) or
otherwise clarify the relationship between these provisions in the
regulation. Given EPA's position that the regulation requires the use
attainability of a water body to be documented before any of its uses
may be removed, EPA is interested in a discussion of specific
attainability issues that might arise in applying the UAA requirements
to non-Section 101(a)(2) uses such as water supply or agriculture.
Information in UAAs
The regulation is not specific about what a UAA should contain
other than the general description contained in the definition of a UAA
at 40 CFR 131.3(g). Instead, EPA has issued various national and
regional guidance documents to assist with the completion of such
analyses. Some have suggested, however, that the regulation be amended
to provide more specificity on information needed in a UAA. Topics for
consideration might include: what specific questions should a use
attainability analysis address? what are the data requirements? and
what are the requirements for reporting the results of the analysis?
EPA seeks comment on this issue.
UAAs and Refinement of ``Fishable/Swimmable'' Use Designation
As long as a State or Tribe designates uses that fall within the
broad range of uses consistent with the section 101(a)(2) goals, there
is no requirement to conduct a UAA. In fact, 40 CFR 131.10(k)
explicitly states that ``a State is not required to conduct a use
attainability analysis . . . whenever designating uses which include
those specified in section 101(a)(2) of the Act.'' As a result, there
does not appear to be a mechanism that ensures State or Tribal waters
are not under-classified (i.e., a use subcategory is designated for a
water when a higher or more protective subcategory is actually
attainable). Some have suggested that the regulation be amended or
guidance clarified to require a UAA (i.e., a structured scientific
assessment) whenever an aquatic life use is designated (or refined) to
ensure the level of protection assigned matches the potential for the
water body. EPA's current thinking is that there needs to be a solid
underlying rationale for use designations. One of the emerging themes
from EPA and the larger community of parties interested in further
protecting water quality is that refining designated uses and tailoring
suites of criteria to the refined uses in watersheds is an important
future direction of this program. Clearly for this approach to succeed,
a solid evaluation of attainability must be at the heart of any
decision to characterize designated uses in greater detail than has
been the norm. EPA is interested in comment on this view, in particular
as it relates to the rebuttable presumption that the generic uses
described as fishable/swimmable are attainable.
Thresholds for Aquatic Life Use Designation
In part 2 of this section, ``Refined Designated Uses'', there is a
discussion explaining EPA's position that the definition of ``aquatic
life'' is not limited to those waters that support ``fisheries.'' That
discussion explains that a more biologically-grounded definition of
aquatic life would be sufficiently expansive to include aquatic
communities made up, for example,
[[Page 36758]]
entirely of invertebrate organisms. This broad definition of ``aquatic
life uses'' has an impact on the manner in which UAAs are planned and
evaluated. The current regulation allows States and Tribes to designate
uses for certain waters that do not include the section 101(a)(2) uses,
where such uses are not attainable. As a result, some States and Tribes
have waters which have not been assigned an aquatic life designated
use. However, if aquatic life uses are defined broadly, as EPA believes
they should be, there would be very few, if any, waters that would not
be considered as supporting some type of existing aquatic life use.
Aquatic communities form a continuum, making it difficult, if not
impossible in the biological sense, to identify where the threshold for
aquatic life use begins. As a result, some have suggested that a broad
definition of aquatic life would appear to revoke the option of
excluding aquatic life protection from a water body since essentially
all waters support some level of aquatic life. They have suggested,
therefore, that there is a need to identify a threshold, based on some
physical rather than biological limitation, that could be used as an
acceptable justification for concluding that an aquatic life use is not
attainable. For example, some States and Tribes have urged the use of a
flow-based threshold to justify a conclusion that an aquatic life use
in not attainable. Generally, ephemeral waters (waters whose channel
does not intersect the ground water table and which are dependent on
precipitation events for their flow) are suggested as an appropriate
threshold. In a biological sense, this may not be a satisfactory
solution since there are ecologically important ephemeral waters which
should receive aquatic life use protection regardless of the temporal
nature of the flow. This is especially true for many ephemeral
wetlands. EPA is considering whether changes are needed in the
regulation or guidance to address whether, and under what
circumstances, UAAs may be used to justify a non-aquatic life use
classification, given the broad range of aquatic communities that may
exist.
Request for Comments on Use Removal and Use Attainability
EPA seeks comment on the following questions:
1. Although EPA believes the use removal criteria in Sec. 131.10(g)
have functioned reasonably well, questions have been raised about the
applicability of specific section 131.10(g) criteria and the manner in
which EPA interprets those criteria. EPA seeks comment on the use
removal criteria. Are the six criteria sufficiently comprehensive or
should other factors be considered as a basis for removing designated
uses? Are the criteria too comprehensive and are certain of the
criteria inappropriate as a basis for designated use removal? Is there
a need to modify the existing criteria to more clearly address the full
range of use removal issues that have developed since the regulation
was originally published?
2. Even with the statements in the current regulation, questions
have been raised about the minimum requirements of a use attainability
analysis. Is there need for further clarification in guidance, policy
or in the regulatory text on this issue?
3. Triennial review of UAA-based use designations that do not
include section 101(a)(2) uses, are currently triggered only when new
information becomes available. Should EPA require that States and
Tribes specify procedures they will use in identifying what constitutes
new information and thus when the review of the UAA-based use
designations is required?
4. Although 40 CFR 131.10(g) requires an assessment of
attainability before removal of any designated use, the regulatory
language does not expressly require an analysis called a UAA as
specified in 40 CFR 131.10(j) any time a State or Tribe seeks to
designate a non section 101(a)(2) use. EPA, however, believes that the
analysis under either provision is equivalent. Should the current
regulation be revised to clarify that the UAA requirements apply to any
``downgrade'' of a use and not just the CWA Section 101(a)(2) uses? Can
any needed clarification be achieved through guidance or policy? EPA
would be interested in comments on factors to be considered in
evaluating the attainability of non Section 101(a)(2) uses, such as
water supply or agricultural uses which generally take place after the
water is diverted from the natural water body.
5. How should the water quality standards regulation, guidance or
policy be modified to provide more specificity on appropriate factors
to consider in developing a use attainability analysis?
6. In order to ensure the present aquatic life use designation (or
use subcategory) matches the attainable level of aquatic life use in a
water body, should the water quality standards regulation, policy or
guidance be modified to clarify that a periodic review of designated
uses is required where a State or Tribe has designated only marginal or
limited aquatic life uses?
7. Are changes needed in the water quality standards regulation,
policy or EPA guidance to address whether, and under what
circumstances, use attainability analyses may be used to justify a non-
aquatic life use classification, given the broad range of aquatic
communities that may exist?
d. Alternatives to ``Downgrade'' of the Designated Use. As
discussed above, where a State or Tribe believes that a particular
designated use is not attainable, States and Tribes have the option of
refining a water body's designated use, for example by creating
subcategories of the use and describing the use in more detail. A
subcategory can, and may need to be, water body-specific if the State's
or Tribe's use classification system is not sufficiently precise to
accommodate the subcategory of designated use for the water body in
question. States and Tribes also have the option of removing the
designated use and replacing the removed use with a new one that, under
the regulation, reflects attainable conditions in the water body. Use
removal and to a lesser extent refinement are also commonly referred to
as use ``downgrade.'' Both of these options, refinement and removal of
the designated use, are not time-limited. That is, the designated use
that results from exercising either of these options becomes the new
goal use of the water body. In the following discussion, three
alternatives to use downgrade that have been used by States are
presented. They are variances, temporary standards, and ambient-based
criteria. These alternatives are less ``draconian'' than use
downgrading in the sense that they can provide adjustments to
particular aspects of the standards--i.e., to the criteria for
particular pollutants or the criteria as applied to certain
dischargers--without changing the designated use and the full suite of
criteria to protect the designated use. EPA's current thinking is that
often the attainable condition of particular water bodies is not well
understood due to uncertainty about expected results of water quality
improvement actions. In such situations, EPA believes it may be
appropriate to implement water quality protection actions, assess the
results of those actions, and implement additional measures where
necessary to continue to improve water quality. EPA believes that
iterative assessment and implementation in these types of situations is
probably the best way to gain an understanding of the ultimate
attainable condition of the water body. The mechanisms described below
may be well-suited to this situation because they leave the designated
use of the
[[Page 36759]]
water body, the ultimate goal, in place while providing a defined
period of time (in the case of variances and temporary standards) to
document, through implementation and assessment, the water quality
improvements that are possible through various measures and thus, the
attainability of the goal.
i. Variances. One option authorized under the regulation that is
used by some States or Tribes is the water quality standard variance. A
variance is a short-term exemption from meeting certain otherwise
applicable water quality standards. EPA authorizes States and Tribes to
include variances in their water quality standards. (see 40 CFR
131.13). Agency guidance on variances identifies what the Agency
believes to be the essential elements of a variance:
--a variance should be granted only where there is a demonstration that
one of the use removal factors (40 CFR 131.10(g)) has been satisfied;
--a variance is granted to an individual discharger for a specific
pollutant(s) and does not otherwise modify the standards;
--a variance identifies and justifies the numerical criteria that will
apply during the existence of the variance;
--a variance is established as close to the underlying numerical
criteria as is possible;
--a variance is reviewed every three years, at a minimum, and extended
only where the conditions for granting the variance still apply;
--upon expiration, of the variance, the underlying numerical criteria
have full regulatory effect;
--a variance does not exempt the discharger from compliance with
applicable technology or other water quality-based limits; and
--a variance does not affect effluent limitations for other
dischargers.
With these safeguards in place, the principal difference between a
variance and a downgrade of a designated use is that a variance is
temporary. That is, when the variance expires, an affirmative showing
would be needed to continue it, or the underlying standards are
applicable. Because a variance is temporary, it actively supports the
improved water quality goal, and it can, under appropriate
circumstances serve as an environmentally preferable alternative to
what otherwise might become a permanent change in a designated use.
Historically, the intent of the variance provision has been to:
provide a mechanism by which permits can be written to meet a modified
standard where discharger compliance with the underlying water quality
standard is demonstrated to be infeasible within the meaning of
Sec. 131.10(g) at the present time (e.g., meeting the standard would
cause substantial and widespread social and economic impact); encourage
maintenance of original standards as goals rather than removing uses
that may be ultimately attainable; and ensure the highest level of
water quality achievable during the term of the variance.
EPA has approved State and Tribal use of variances when the
individual variance is included in State or Tribal water quality
standards, each variance is subject to the same public review as other
changes in water quality standards, the State or Tribe demonstrates
that meeting the standard is unattainable based on one or more of the
grounds listed in 40 CFR 131.10(g) for removing a designated use,
existing uses are protected, the variance secures the highest level of
water quality attainable short of achieving the standard and the State
or Tribe demonstrates that advanced treatment and alternative effluent
control strategies have been considered (See 48 FR 51400, 51403 (Nov.
8, 1983); Water Quality Standards (WQS) Handbook at 5-12; Memorandum
from EPA's Office of Water, ``Variances in Water Quality Standards,''
March 15, 1985; and Decision of the General Counsel No. 58, In Re
Bethlehem Steel Corporation, March 29, 1977).
The Preamble to the 1983 water quality standards regulation
revision suggested that substantial and widespread social and economic
impact, the sixth element for use removal under Sec. 131.10(g), is an
important and appropriate test that, if met, could be used as the basis
for granting a variance (see 48 FR 51403). Subsequently, on March 15,
1985, EPA issued further guidance on the conditions under which a
variance might be granted. The 1985 EPA Office of Water guidance
explained that it would be appropriate to grant short-term variances to
individual dischargers based on any of the six factors for removing a
designated use as listed at Sec. 131.10(g). As variances represent a
temporary downgrade in the water quality standards, EPA reasoned that
more stringent treatment of variances than permanent downgrades would
not be appropriate. In practice, however, the only factor that is
commonly used to grant a discharger-specific variance is the economic
test. The Office of Water guidance continued to interpret variances as
being limited to individual dischargers.
In ``Guidance for State Implementation of Water Quality Standards
for CWA Section 303(c)(2)(B)'' (December 1988; Notice of Availability
published at 54 FR 346, January 5, 1989), EPA recommends that States
and Tribes adopt a variance provision whenever adopting statewide or
tribe-wide criteria for a large number of toxic pollutants for human
health or aquatic life protection. The rationale behind this
recommendation was to avoid unreasonable consequences from adopting
State- or Reservation-wide criteria which could underestimate or
overestimate the toxic potential of some pollutants in a specific water
body.
The Water Quality Guidance for the Great Lakes System (Great Lakes
Guidance) published March 1995 by EPA (56 FR 15366, March 23, 1995; 40
CFR section 132) contains provisions allowing for variances from water
quality standards. Variances granted under the Great Lakes Guidance are
pollutant-specific and point source-specific and are limited to five
years or the term of the NPDES permit implementing the variance,
whichever is less. Variances may be granted for any of the reasons
listed at 40 CFR 131.10(g) for which a use downgrade may be considered.
Like all revisions to State or Tribal water quality standards, EPA
review and approval is required of any variance granted by a State or
Tribe and variances may be renewed following the same procedure
originally used for applying for a variance. Variances are also subject
to review as part of a State's or Tribes triennial review of water
quality standards. Multiple discharger variances (a variance that
applies to multiple point sources discharging to the same water body)
are also allowed under the Great Lakes Guidance. Variances granted
under the Great Lakes Guidance provisions may not jeopardize the
continued existence of any Federally listed threatened or endangered
species. Further, under the Guidance, variances are not available for
new or recommencing discharges. A recommencing discharge is a source
that recommences discharge after terminating operations. (40 CFR
122.2).
The Great Lakes Guidance was developed in concert with many other
provisions addressing designated uses, criteria, antidegradation and
various implementation policies for the Great Lakes States and Tribes.
Any evaluation of the level of protection afforded water quality under
the Great Lakes Guidance variance procedures should be made in the
context of the Great Lakes Guidance as a whole. Similarly, the water
quality standards regulation is more than simply the sum of its parts.
Any
[[Page 36760]]
approach to the implementation of water quality standards variances
must be evaluated in the context of the entire regulation.
EPA is considering whether implementation of the variance provision
has been a useful component of the water quality standards program, and
the overall program for protection of water quality standards. In 1990,
EPA conducted a survey of State variances and variance provisions
(National Assessment of State Variance Procedures, Report, November
1990, Office of Water Regulations and Standards). This study showed
that variances had been granted on a very limited basis. In fact, only
16 out of 57 States and Territories had granted variances and some of
those had done so infrequently. EPA lacks detailed information on why
variances are not being significantly utilized in most States and
Tribes. EPA is interested in information regarding alternative
mechanisms that are being used by States or Tribes in lieu of variances
to provide necessary short term and temporary relief from applicable
criteria, and how any alternative approaches address the feasibility of
ultimately attaining the criteria associated with the underlying
designated use.
EPA is considering whether it would be useful to include in the
regulation more explicit language reflecting current EPA thinking and
practice regarding variances. As explained above, in order to issue
variances, States or Tribes must include variances as part of the
State's or Tribe's water quality standards. EPA believes, however, that
in some instances States may be misusing variances. For example, over
the years, there have been instances where a State has improperly
granted a ``variance'' from compliance with NPDES permit limits,
failing to include these variances within the water quality standards
themselves. There has also been some confusion regarding the necessity
of formal adoption of individual variances into State and Tribal water
quality standards and whether the public participation process
associated with NPDES permit issuance sufficiently addresses those same
needs for variance adoption. EPA is also considering whether to specify
the degree to which individual dischargers must document the continued
need for a variance before the variance can be renewed at each
triennial review. EPA is considering whether the water quality
standards regulation should provide more specific guidelines on the use
and content of variance policies. EPA's current thinking is that the
regulation may need to articulate certain aspects of variances more
explicitly, including:
--explicit reference to the criteria listed in 40 CFR 131.10(g) as the
criteria for granting a variance;
--explicit statement that the granting of a variance may not result in
any loss or impairment of an existing use;
--explicit statement that before a variance can be granted, the
applicant must provide documentation that treatment more advanced than
that required by sections 303(c)(2)(A) and (B) of the CWA has been
carefully considered, and that alternative effluent control strategies
have been evaluated and reasonable progress is being made toward
meeting the underlying or original standards;
--explicit statement requiring the highest level of water quality
achievable under the relaxed, interim standard during the period of the
variance.
--explicit statment that a variance shall not be granted if standards
will be attained by implementing cost-effective and reasonable best
management practices for nonpoint source control.
EPA believes that such a clarification of its policy regarding
variances could serve to encourage proper use of variances by States
and Tribes while at the same time reducing the possibility of
inappropriate use.
ii. Temporary Standards. As indicated in the discussion on
variances above, the 1985 EPA Office of Water guidance explained that
it would be appropriate to grant short-term variances to individual
dischargers based on any of the six factors for removing a designated
use as listed at Sec. 131.10(g). Of the six use removal factors, the
first five address water quality and habitat features of the water body
as a whole. These same factors are not, however, ideally suited to
making decisions about the capabilities of individual dischargers. For
example, it is not immediately clear how use removal factor five,
``physical conditions related to natural features of a water body * * *
preclude attainment of a use'', could be applied to a decision about an
individual discharger. On the other hand, the sixth factor, the
substantial and widespread economic and social impact factor, is well
suited to decisions about individual dischargers which explains why the
economic hardship test has been historically applied in evaluating
variances.
Several States have applied factors similar to the first five use
removal factors in establishing variances for entire water body
segments or portions of water body segments. These States sometimes
refer to these as ``temporary standards'' or ``temporary
modifications''. This has been done where the problems in a water body
are significant and widespread, involving point and nonpoint sources of
pollution and their impacts on water quality and habitat, that is
waters significantly impaired by multiple sources and not just one or a
few point sources. For example, where historic mining practices have
severely impaired both water quality and habitat throughout a headwater
basin, temporary standards have been used. Rather than downgrading
these waters, the States have applied temporary standards with specific
expiration dates for certain pollutants affected by the historic mining
practices. In this way, the States have maintained designated uses and
underlying criteria for other pollutants, while recognizing that
existing ambient conditions for certain pollutants are not correctable
in the short-term. In such cases, the temporary standards provide a
basis for permit limits in the shorter-term. The temporary standards
approach is then used by these States as the basis for remediation of
damaged water resources because the underlying designated use and
criteria to protect that use actively drive water quality improvements
in the longer-term. EPA Regional Offices have approved the use of such
temporary standards.
Temporary standards have been implemented to date with little
specific Agency guidance on a water body approach to variances. EPA is
considering whether the water quality standards regulation or guidance
should specifically address temporary standards. EPA's current thinking
is that if the regulation or Agency guidance were to specifically
address temporary standards, such regulation or guidance would need to
address certain relevant issues including: application criteria to be
used in deciding which waters might qualify for temporary standards; a
way of identifying the existing, impaired water quality conditions; a
mechanism for specifying the water quality needed to fully attain the
anticipated uses; and a plan and driving mechanism aimed at achieving
needed water quality and habitat improvements to fully support
compliance with the designated uses.
Where EPA has provided guidance to individual States on use of
State temporary standards provisions, EPA has advised that any
temporary standard should:
--be granted only where there is a demonstration that one of the use
removal factors (40 CFR 131.10(g)(1) through (6) has been satisfied;
[[Page 36761]]
--be granted for a specific water body or portion of a specific water
body as defined in State standards;
--identify and justify the numerical criteria that will apply during
the existence of the temporary standard and identify a ``remediation
plan'' aimed at compliance with the underlying designated uses and
criteria;
--be established as close to the underlying numerical criteria as is
possible;
--be reviewed every three years, at a minimum, and extended only where
the conditions for granting the temporary standard still apply;
--be in effect only for the specified term of the temporary standard
(or extension thereof), and upon expiration of the temporary standard,
the underlying numerical criteria have full regulatory effect;
--not exempt any discharge to the water body from compliance with
applicable technology or water quality-based limits (based on the
temporary standards) or best management practices;
--not apply to any new discharger to the water body; and
--protect existing uses.
EPA is considering whether the use of temporary standards
represents a viable alternative to use refinement or removal. EPA is
also considering whether the regulation or guidance should explicitly
address use of temporary standards, including specific limitations on
the use of temporary standards like those listed above.
iii. Ambient-based Criteria. On a limited basis, States have
developed and EPA has approved ``ambient-based criteria.'' These
ambient-based criteria have been developed for specific water bodies
and pollutants where such criteria are shown to protect the designated
use and the existing use. EPA believes that ambient-based criteria can
be preferable to a ``downgrade'' of a use because the underlying
designated use is retained and because they may be limited to only a
small subset of pollutants.
EPA has issued a policy memorandum concerning one type of ambient-
based criteria, site-specific criteria for aquatic life protection that
are based on natural conditions. (See Memorandum from Tudor T. Davies,
Director Office of Science and Technology, Subject: Establishing Site-
Specific Aquatic Life Criteria Equal to Natural Background, November 5,
1997.) This policy states that States and Tribes may establish site-
specific aquatic life criteria equal to natural background conditions,
but such criteria must be scientifically defensible. Additionally, the
State's or Tribe's water quality standards should contain or provide
specific authority for site-specific criteria based on natural
background. States and Tribes should also identify procedures for
determining natural background. EPA's current policy also states that
the State or Tribal procedure for determining natural background needs
to be specific enough to establish natural background concentration
accurately and reproducibly. States and Tribes should also provide for
public notice and comment on the provision, the procedure and the site-
specific application of the procedure. The States or Tribes will also
need to document the resulting site-specific criteria in its water
quality standards, including specifying the water body segment the
site-specific criterion applies to. This can be accomplished through
adopting the site-specific criteria into the State and Tribal water
quality standards, or, alternatively by appending the site-specific
criteria to the water quality standards.
In addition, a second approach that some States have used and EPA
has approved is where the State or Tribe could have met the test for
downgrading a use under 40 CFR 131.10(g)(3) i.e., ``Human caused
conditions or sources of pollution prevent the attainment of the use
and cannot be remedied or would cause more environmental damage to
correct than to leave in place'', but instead of downgrading the use,
the State or Tribe established certain criteria based on ambient
conditions where those ambient conditions were shown to be
irreversible. In addition to assuring that the existing use is
protected, EPA is interested in assuring that where the ambient
concentration of a pollutant cannot be improved, i.e., it is
irreversible, that such condition be maintained and not made worse.
When this occurs, EPA believes that for other pollutants in the same
water body for which applicable criteria are being or can be met, those
criteria should remain in place and not be made less protective via a
use downgrade. EPA's current thinking is that the ambient-based
criteria need to be the best attainable. In addition, EPA's current
thinking is that in order to establish ambient-based criteria, the
State or Tribe should conduct an analysis equivalent to a use
attainability analysis for a downgrade that should include a thorough
description of the biota that will be protected via applicable water
quality criteria (both the unchanged pre-existing criteria and the
ambient-based criteria).
EPA is interested in hearing comments regarding these ambient-based
criteria mechanisms, and specifically whether the regulation should
discuss these mechanisms more specifically, and whether the regulation
should be more explicit about the biological evaluation necessary to
describe the aquatic life use being protected. EPA is also interested
in comments on whether the other relief mechanisms based on the
Sec. 131.10(g) reasons, such as variances and temporary standards,
should also require criteria which reflect the best attainable
conditions.
Request for Comments on Alternatives to Downgrading a Designated Use
EPA seeks comment on the following questions:
1. EPA requests comment on whether variances, temporary standards
and/or ambient-based criteria can under certain circumstances offer an
environmentally preferable alternative to refinement or removal
(downgrade) of the designated use? Under what circumstances?
2. Does the current water quality standards regulation or Agency
guidance or policy discourage persons from seeking variances and/or
discourage States and Tribes from granting variances (including
temporary standards)? What components of the procedures are most
problematic?
3. Reflecting EPA's current interpretation of the regulation,
should the regulation make explicit that individual variances and
temporary standards must be documented in a State's or Tribe's water
quality standards before implementation as part of NPDES permits?
4. Reflecting EPA's current interpretation of the CWA and the
regulation, should the regulation contain express reference to the
factors listed in 40 CFR 131.10(g) as the criteria under which a
variance (including temporary standards) from water quality standards
will be allowed? Should any of these factors be deleted? Should any new
factors be added?
5. Reflecting EPA's current interpretation of the CWA and the
regulation regarding existing uses, should the variance portion of the
regulation at 40 CFR 131.13 underscore that the granting of a variance
must not result in any loss or impairment of an existing use, for
example by cross-referencing the requirement at 40 CFR 131.12(a)(1)
that existing uses must be protected?
6. To reflect current practice and EPA guidance, should the
regulation be
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amended to require documentation by either the applicant or the State
or Tribe demonstrating that treatment more advanced than that required
by sections 303(c)(2)(A) and (B) of the CWA has been carefully
considered, and that alternative effluent control strategies have been
evaluated and reasonable progress is being made toward meeting the
underlying or original standards?
7. Should the regulation require that States and Tribes document in
their water quality standards the criteria that are applicable to the
water body or segment thereof during the period of a variance or
temporary standards?
8. Should the regulation discuss ambient-based criteria mechanisms
more specifically?
9. Should the regulation be more explicit about the biological
evaluation necessary to describe the aquatic life use being protected
where ambient-based criteria are used?
10. EPA is also interested in comments on whether the other relief
mechanisms based on the Sec. 131.10(g) reasons, such as variances and
temporary standards, should in the regulation, expressly be required to
require criteria which reflect the best attainable conditions?
11. Do the alternatives to use removal help address pulsed or
intermittent impacts, such as those from urban and rural runoff?
C. Criteria
The following section discusses water quality criteria in the water
quality standards programs. EPA is considering the implementation of
and effectiveness of different types of criteria and on the
desirability of changes to the water quality standards regulation as it
pertains to criteria. The scope of the criteria section includes all
Clean Water Act criteria for which EPA has issued national criteria
guidance, and several types of criteria for which there is no national
criteria guidance but where criteria guidance and policy are being
contemplated.
1. Background
Water quality criteria are levels of individual pollutants or water
quality characteristics, or descriptions of conditions of a water body
that, if met, will generally protect the designated use of the water.
EPA, under section 304(a) of the Act, periodically publishes
recommendations (guidance) for use by States and Tribes to set water
quality criteria. Water quality criteria are developed to protect
aquatic life and human health, and in some cases wildlife, from the
deleterious effects of pollutants and other effects of pollution. There
are three principal categories of water quality criteria: criteria to
protect human health, criteria to protect aquatic life, and criteria to
protect wildlife. Within these broad categories, there are different
types of criteria, for example within the human health category, there
are chemical-specific and microbiological criteria. Within the aquatic
life category, there are chemical-specific criteria, toxicity criteria,
biological criteria, sediment criteria and physical criteria such as
habitat and flow balance. These criteria may be expressed in either
narrative or numeric forms. Many of these criteria may be developed to
apply generally, or they may be developed to apply to site-specific
situations. The CWA section 303(a)-(c) requires all States, and any
Tribe that has water quality program authority, to evaluate the need
for water quality criteria to protect a designated use and then adopt
water quality criteria (either EPA's or its own) sufficient to protect
uses designated for State or Tribal waters. Economic and technological
factors (e.g., the ability of analytical techniques to detect the
pollutant and treatment cost considerations) may not be used to justify
adoption of criteria that do not protect the designated use.
Narrative criteria are descriptions of conditions necessary for the
water body to attain its designated use. Often expressed as ``free
from'' certain characteristics, narrative criteria can be the basis for
controlling nuisance conditions, e.g. floating debris or objectionable
deposits. Narrative criteria are often the basis for limiting toxicity
in discharges. States and Tribes establish narrative criteria where
numeric criteria cannot be established or to supplement numeric
criteria under 40 CFR 131.11(b)(2). When a water body is classified for
more than one use, criteria necessary to protect the most sensitive use
must be applied to the water body. 40 CFR 131.11(a).
CWA section 304(a) directs EPA to develop criteria guidance. These
criteria recommendations assist States and Tribes in developing water
quality standards. The AWQC are published pursuant to Section 304(a)(1)
of the CWA which states:
The Administrator * * * shall develop and publish * * * (and
from time to time thereafter revise) criteria for water quality
accurately reflecting the latest scientific knowledge (A) on the
kind and extent of all identifiable effects on health and welfare
including, but not limited to, plankton, fish, shellfish, wildlife,
plant life, shorelines, beaches, esthetics, and recreation which may
be expected from the presence of pollutants in any body of water,
including ground water; (B) on the concentration and dispersal of
pollutants, or their byproducts, through biological, physical, and
chemical processes; and (C) on the effects of pollutants on the
biological community diversity, productivity, and stability,
including information on the factors affecting rates of
eutrophication and rates of organic and inorganic sedimentation for
varying types of receiving waters.
Pursuant to section 304(a), EPA has developed to date, aquatic life
criteria guidance for 31 chemicals and human health criteria guidance
for 100 chemicals. For the most part, States and Tribes have found such
EPA criteria guidance useful in setting standards to protect designated
uses. Since 1980, most States and Tribes have adopted at least some of
the criteria guidance published by EPA pursuant to CWA section 304(a).
However, EPA's resources available to develop criteria guidance are
limited. Thus, there are cases where the scientific information or data
necessary to develop criteria exist but EPA has been unable to
establish section 304(a) criteria guidance.
States and Tribes may establish numeric criteria using CWA section
304(a) criteria guidance, section 304(a) criteria guidance modified to
reflect site-specific conditions, or other scientifically defensible
methods. 40 CFR 131.11(b)(1). There are situations where EPA relies on
the 304(a) criteria guidance when promulgating replacement standards
for a State or Tribe pursuant to section 303(c). EPA promulgation of
304(a) criteria for States or Tribes is discussed in more detail below.
Numeric criteria are values expressed as levels, concentrations,
toxicity units, or other numbers deemed necessary to protect designated
uses. Water quality criteria developed under Section 304(a) are based
solely on data and scientific judgments on the relationship between
pollutant concentrations and environmental and human health effects.
EPA criteria under section 304(a) do not reflect consideration of
economic impacts or the technological feasibility of meeting the
chemical concentrations in ambient water. As discussed below, 304(a)
criteria are used by States and Tribes to establish water quality
standards, and ultimately provide a basis for controlling discharges or
releases of pollutants.
Numeric criteria are important because they provide a proven
effective basis for implementation of the CWA. For example, these
criteria often form the basis for NPDES water quality-based permit
limits for point source dischargers and for establishing TMDLs for a
water body as a whole. Numeric criteria can also be useful in assessing
[[Page 36763]]
and managing nonpoint source pollution problems.
The Act uses the term ``criteria'' in two separate ways. In section
303(c), the term is part of the definition of a water quality standard.
That is, a water quality standard is comprised of designated uses, and
the criteria necessary to protect those uses. Thus, States and Tribes
are required to adopt regulations that contain legally enforceable
criteria. However, in section 304(a) the term ``criteria'' is used in
the scientific sense. That is, under section 304(a), EPA develops
scientifically sound criteria guidance which may form the basis for
State, Tribal or Federal adoption of water quality standards pursuant
to section 303(c). Thus, two distinct purposes are served by the
section 304(a) criteria. The first is as guidance to the States and
Tribes in the development and adoption of water quality criteria that
will protect designated uses, and the second is as the basis for
promulgation of legally enforceable water quality criteria by the State
or Tribe, or via a superseding Federal rule when such action is
necessary.
As with all science, new information leads to new insights
concerning pollutant impacts on water quality. This ongoing evolution
affects two important and inter-related responsibilities of the Agency,
which are carried out concurrently. First, from time to time EPA
revises the 304(a) water quality criteria to reflect the latest data
and advances in criteria science. EPA compiles the current water
quality criteria guidance from time to time in a series of guidance
documents: the Green Book in 1968, the Blue Book in 1972, the Red Book
in 1976, and the Gold Book in 1986. The second responsibility pertains
to the requirements of section 303(c).
As part of the water quality standards triennial review process
defined in section 303(c)(1), the States and Tribes are responsible for
maintaining and revising water quality standards. Section 303(c)(1)
requires States and Tribes to review, and modify if appropriate, their
water quality standards at least once every three years. If EPA
determines that a new or revised standard is not consistent with the
requirements of the CWA, or EPA determines that a revised standard is
necessary to meet the requirements of the Act, Section 303(c)(4)
authorizes EPA to promulgate replacement water quality standards. From
time to time EPA has chosen to undertake such promulgations. In doing
so, EPA considers the most current available scientific information,
such as toxicity data and exposure assumptions.
With a number of Federal promulgations of water quality criteria
under section 303(c)(4) occurring over time, or the publication of a
new or revised 304(a) criteria guidance document, the criteria value(s)
in an earlier Federal action may differ from the value(s) in a
subsequent Federal action. This has led to some confusion among the
public with regard to what EPA's current section 304(a) water quality
criteria may be for a given chemical at any given time, and, what
values EPA would promulgate for a State or Tribe under section 303(c).
Currently, EPA interprets the most recent Federal action, whether taken
pursuant to 303(c) or 304(a), as establishing the current section
304(a) criteria guidance. When EPA determines that a Federal rule is
necessary to correct deficiencies in State criteria, EPA looks to the
most recent criteria science, as articulated in either section 304(a)
criteria guidance or EPA's most recent statement contained in a
proposed or final section 303(c) rule.
To date, the most recent Federal recalculation of section 304(a)
criteria occurred in the proposed California Toxics Rule (CTR)(62 FR
42160), July 30, 1997. The proposed CTR was undertaken pursuant to CWA
section 303(c)(2)(B). In the Water Quality Act of 1987, Congress
increased the emphasis on numeric criteria for toxic pollutants by
enacting section 303(c)(2)(B). This section requires all States and any
Tribe with water quality standards authority to adopt ambient water
quality criteria for toxics (priority pollutants) for which EPA has
published criteria under section 304(a), and for which the discharge or
presence could reasonably be expected to interfere with the designated
use adopted by the State or Tribe. In adopting such criteria, States
and Tribes must establish numerical values based on: (1) 304(a)
criteria; (2) 304(a) criteria modified to reflect site-specific
conditions; or, (3) other scientifically defensible methods.
Again, EPA views the criteria program as constantly evolving.
Whenever new or revised criteria are published, whether under 304(a) or
a rule under 303(c), that action establishes the Agency's most current
section 304(a) criteria guidance.
Whenever a State or Tribe revises its water quality criteria EPA
compares the State criteria values and the basis of their derivation to
the criteria contained in the most recent Federal action (either
303(c)(4) rule making or 304(a) criteria guidance publication). Thus,
there may be cases where the applicable policies and science have
evolved such that EPA would be comparing State or Tribe adopted
criteria values to Federal criteria values other than those in older
rules or criteria guidance to determine whether to approve the State's
or Tribes's criteria. This approach is necessary to encourage State and
Tribal adoption of the most recent section 304(a) criteria.
2. Ambient Water Quality Criteria to Protect Aquatic Life
Aquatic life criteria are scientifically-derived values, derived by
States, Tribes, or EPA, to protect aquatic life from the deleterious
effects of pollutants in ambient water. States and Tribes may use EPA's
section 304(a) criteria guidance in developing such criteria. When
developing numeric aquatic life criteria, States and Tribes usually
express two concentrations; one that protects against acute effects
(effects from short term exposure) and one that protects against
chronic effects (effects from long term exposure). The short-term
concentration is expressed as a Criterion Maximum Concentration (CMC)
and is the highest ambient concentration of a toxicant to which aquatic
organisms may be exposed for a short time period without causing an
unacceptable effect. The long-term concentration is expressed as a
Criterion Continuous Concentration (CCC) and is the highest ambient
concentration of a toxicant to which aquatic organisms can be
continuously exposed without causing an unacceptable effect.
Water quality criteria to protect aquatic life consist of three
components--magnitude, duration and frequency. Magnitude refers to the
acceptable concentration of a pollutant. Duration is the period of time
(averaging period) over which the ambient concentration is averaged for
comparison with criteria concentrations. Frequency is how often the
criteria can be exceeded to allow the aquatic community sufficient time
to recover from excursions of aquatic life criteria and to thrive after
recovery.
The numerical aquatic life criteria are expressed as short-term and
long-term concentrations in order that the criteria more accurately
reflect toxicological and practical realities. The combination of a
Criterion Maximum Concentration (CMC), over a one-hour acute duration
(a short-term average acute limit), and a Criterion Continuous
Concentration (CCC), over a four-day chronic duration (a long-term
average chronic limit) provide protection of aquatic life and its uses.
Recommended averaging periods are kept relatively short because
excursions higher than the average can
[[Page 36764]]
kill or cause substantial damage in short periods.
The frequency limitations specify that both the acute and chronic
criteria may be exceeded once in a three-year period on the average.
The recommended once in a three-year period coupled with the 4-day
chronic averaging period used for the CCC approximately corresponds to
the historically used criterion concentrations that occurs in a once-
in-ten year seven-day-average low flow (7Q10). The once-in-three-year
period coupled with the one-hour acute averaging period used for the
CMC approximately corresponds to the historically used criterion
concentration that occurs in a once-in-ten year one-day-average low
flow (1Q10)
The method by which EPA derives criteria is updated from time to
time, to incorporate advances in the science. To overcome the
limitations in the previous approaches to duration and frequency, a new
risk assessment methodology is being developed. EPA expects that the
new risk assessment methodology will include an approach that will
better handle variable concentrations by use of a kinetic-based
toxicity model coupled with a population response model. A kinetic-
based toxicity model considers the speed at which effects appear in
different individuals and at different concentrations. The kinetic-
based model allows prediction of the toxicity of any series of time-
variable concentrations. It can predict how often effects would occur,
and what fraction of individuals in the species would be affected.
To weigh the full impact that a particular time series of
concentrations would have on the exposed population of a species, an
additional factor is being considered: how long it takes to replace
those individuals lost due to the toxic effects. Consideration of this
involves the use of a population model indicating rates of recovery of
different taxonomic groups to stresses. The intent of this part of the
derivation is to allow the toxic impact to be portrayed as the overall
average reduction in the number of individuals in a species, both
during lethal or sublethal periods and during recovery periods,
accounting for both partial lethality and partial recovery.
Request for public comment on Aquatic Life Criteria
EPA requests comments on the following question:
1. Prior to completion of all of the aquatic life methodology
revisions, should EPA use the tools that have thus far been developed
(the kinetic model of individual organism response to derive the
appropriate duration/averaging period of the criterion or to evaluate
mixing zone alternatives and the population effects model to derive the
allowable frequency of excursion above the criterion) to re-examine and
possibly revise its recommendations on the duration and frequency of
criteria excursions?
3. Site-Specific Criteria
EPA also provides guidance on how States and Tribes may develop
site-specific numeric aquatic life criteria that are either more or
less stringent than the criteria adopted by the State or Tribe and that
would normally apply to a water body. Currently, national guidance only
has recommendations and methods for establishing site-specific water
quality criteria for aquatic life but guidance is under development for
deriving site-specific sediment quality criteria as well.
The regulation currently specifies that States and Tribes may adopt
numeric criteria based on published CWA section 304(a) guidance,
section 304(a) guidance modified to reflect site-specific conditions,
or other scientifically defensible methods. 40 CFR 131.11(b). EPA
recognizes that States and Tribes may want to develop numeric criteria
that vary from CWA section 304(a) guidance for specific waters (e.g.,
where chemical and physical characteristics of local waters alter the
bioavailability and/or toxicity of a pollutant; or when the species or
community actually present or desired may be more or less sensitive
than the species or community represented by the criteria database.) In
such situations, a site-specific criterion may be appropriate. EPA has
developed and continues to develop guidance to assist States and Tribes
in the development of site-specific criteria. (See Water Quality
Standards Handbook, Second Edition, EPA 823-B-94-005a, August, 1994, pp
3-38 through 3-45 and documents cited therein.)
Site-specific criteria are allowed by regulation and must be
submitted to EPA for review and approval, as are any changes to a WQS.
The regulation at 40 CFR 131.11(b)(1) specifically provides States and
authorized Tribes with the opportunity to adopt water quality criteria
that are ``* * * modified to reflect site specific conditions.'' Under
40 CFR 131.5(a)(2), EPA reviews State and Tribal standards to determine
``whether a State has adopted criteria to protect the designated uses''
and whether such criteria are scientifically defensible (40 CFR
131.11(b)).
Existing guidance and practice are that EPA will approve site-
specific criteria developed on the basis of sound scientific
rationales.
Currently, EPA has specified three scientifically defensible
procedures that States and Tribes may follow in deriving site-specific
aquatic life criteria. These are the Recalculation Procedure, the
Water-Effect Ratio Procedure and the Resident Species Procedure. These
procedures can be found in the Water Quality Standards Handbook (USEPA,
1994). States may also develop other procedures for deriving such
criteria as long as they are scientifically defensible. EPA also
recognizes there may be naturally occurring concentrations of
pollutants that may exceed the national criteria guidance published
under Section 304(a) of the Clean Water Act.
The Great Lakes Guidance contains a procedure for developing site-
specific criteria for protection of wildlife. While the Great Lakes
States and Tribes must adopt a procedure consistent with that
procedure, other States and Tribes may derive site-specific criteria
using the procedure in the Great Lakes Guidance and such criteria can
be more or less stringent than the applicable wildlife criteria where
scientifically defensible. This is most likely to be in cases where a
site-specific Bioaccumulation Factor (BAF) has been developed.
The Great Lakes Guidance also provides a procedure for modifying
human health criteria on a site-specific basis based on differences in
fish consumption or BAF. With regard to aquatic life criteria, if a
State or Tribe could demonstrate that physical or hydrological
conditions preclude aquatic life from remaining at a site for a period
of time in which acute or chronic effects may occur, less stringent
site-specific aquatic life criteria are allowed.
EPA's current thinking is that States and Tribes should identify in
their water quality standards the methods they intend to use for site-
specific criteria development and generally the circumstances under
which such criteria may be developed. Additional discussion and request
for comment on emerging rationales and methods for site-specific
criteria, beyond that described and referenced above, is contained in
section B.4.d of this notice, entitled ``Alternatives to Removal of the
Designated Use.''
Request for Comments on Site-Specific Criteria
EPA seeks public comment on the following questions:
1. Should the regulation be modified to require States and Tribes
to specifically authorize and identify the procedures for developing
site-specific water quality criteria? Would additional EPA guidance be
necessary?
[[Page 36765]]
2. Should the regulation or EPA guidance specify the circumstances
under which site-specific criteria are necessary?
3. Does EPA need to develop guidance, policy, or clarify the
regulation regarding site-specific criteria based on ambient
conditions?
4. Should EPA explore broadening the concept of site-specific
criteria to include watershed-specific or ecosystem-specific criteria
perhaps in conjunction with a refined use designation? If so, what type
of additional guidance or policy is necessary to fully explain these
concepts and are any changes to the regulation needed to enable and/or
facilitate use of watershed or ecosystem-specific criteria?
4. Narrative Water Quality Criteria
Narrative criteria can be an effective tool for controlling the
discharge of pollutants when numeric criteria are not available.
Narrative criteria, which have become known as ``free froms'', were
first developed in 1968 and continue to be used in State and Tribal
water quality standards. EPA guidance explains that these ``free
froms'' apply to all waters of the United States at all flow conditions
(including ephemeral and intermittent streams) (see Water Quality
Standards Handbook: Second Edition (EPA-823-B-94-006, August 1994).
Narrative 'free from' criteria guidance indicates that all waters be
free from substances, for example, that (a) cause toxicity to aquatic
life or human health, (b) settle to form objectionable deposits, (c)
float as debris, oil, scum and other materials in concentrations that
form nuisances, (d) produce objectionable color, odor, taste or
turbidity, or (e) produce undesirable aquatic life or result in the
dominance of nuisance species.
The toxic ``free froms'' include protection from both chronic and
acute toxicity and include all pollutants which cause toxic effects,
including but not limited to those listed under Section 307(a) if
necessary to protect the designated use. All States have adopted
narrative water quality criteria pursuant to section 303(c). See 48 FR
51400-51402, November 8, 1983. EPA guidance interprets these ``free
froms,'' as with all criteria, to apply to the ambient water quality,
not distinguishing between point sources and nonpoint sources of
toxicity.
Currently, 40 CFR 131.11(a)(2) of the water quality standards
regulation requires States and Tribes that have established narrative
criteria for toxic pollutants to identify the methods by which the
State or Tribe intends to regulate point source discharges of toxic
pollutants based on such narrative criteria. EPA regulations at 40 CFR
122.44(d)(1)(v) and (vi) require narrative criteria to be implemented
through NPDES permit limits. More specifically, when the permitting
authority determines that a discharge causes, has the reasonable
potential to cause, or contributes to an excursion above a narrative
criterion, the permit must, under most circumstances, contain effluent
limits for whole effluent toxicity. In addition, where the permitting
authority determines that a specific pollutant for which the State or
Tribe has not adopted a chemical criterion is in a discharge in an
amount that causes, has the reasonable potential to cause, or
contributes to an excursion above a narrative criterion, the permit
must contain effluent limits for that pollutant that are based on an
interpretation of the State's or Tribe's narrative criterion. The
regulation provides three options for interpreting the narrative
criterion, and in addition, EPA has provided guidance on this
requirement in both the Technical Support Document for Water Quality-
Based Toxics Control and the Water Quality Standards Handbook (both
Cited above). The guidance advises States and Tribes to develop
implementation procedures that explain the application and integration
of all mechanisms used by the State or Tribe to ensure that narrative
criteria are attained (e.g., chemical-specific requirements, whole
effluent toxicity requirements, and biological criteria, where
biological criteria programs have been developed by the State or
Tribe). The rationale for this approach is that comprehensive written
procedures facilitate implementation decisions, reduce inconsistencies
that can result in different requirements for similar situations, and
promote effective and sensible application of narrative toxics
criteria.
Although all States and Tribes have some type of customary practice
for implementing narrative criteria, and many States and Tribes have
developed implementation policies on narrowly defined topics (e.g., to
explain application of whole effluent toxicity testing requirements),
very few, if any, States and Tribes have developed comprehensive
written implementation procedures that address all of the narrative
toxics criteria implementation issues. The result may be inconsistent
application of narrative toxics requirements within those States and
Tribes that have not developed such procedures. In addition, the lack
of documented methods makes it difficult for EPA to evaluate whether
aquatic life and or human health is being adequately protected.
Request for Comments on Narrative Criteria
EPA seeks public comment on the following questions:
1. Should the regulation require adoption of ``free froms'' and
similar criteria as being the minimum floor allowable under the Clean
Water Act.
2. Reflecting current practice, should the regulation specify that
States and Tribes are required to adopt narrative criteria for all
waters?
3. At this time, EPA has limited information about how States and
Tribes are implementing narrative criteria with regard to nonpoint
source activities. How can narrative criteria best be implemented in
the nonpoint source context and what might EPA do, including modifying
the regulation, to enhance or further the use of narrative criteria?
4. Does the existing requirement for States and Tribes to identify
methods for implementing narrative toxics criteria need to be
clarified, and if so, should EPA clarify the requirement with
additional guidance, or with revisions to the regulation?
5. What minimum elements should be included in an implementation
method for narrative toxics criteria? Should implementation methods
describe application and integration of all of the various mechanisms
used to regulate point sources, or should such methods focus on only
certain aspects of toxics control (e.g., chemical-specific limits,
whole effluent toxicity limits)?
6. The current regulation requires the State or Tribe to identify
the method by which the State or Tribe intends to regulate point source
discharges of toxic pollutants on water quality limited segments based
on such narrative criteria.
Should this narrative criteria translation method apply only to
point source discharges of toxic pollutants on water quality limited
segments or to both point and non-point sources?
7. Should the regulation more explicitly require implementation
procedures for narrative criteria other than toxics criteria? Should
the regulation include minimum requirements for these implementation
procedures?
5. State or Tribe Derived Criteria
States and Tribes may develop their own criteria although the water
quality standards regulation 40 CFR 131.11 provides that where such
criteria are less stringent than 304(a) criteria
[[Page 36766]]
guidance, the State or Tribe must demonstrate the criteria are
scientifically defensible. Despite this available flexibility, and for
a variety of reasons, most States and Tribes are reluctant to derive
their own criteria. EPA is evaluating whether either changes to the
water quality standards regulation or development of additional
guidance would assist State or Tribal efforts to develop protective
criteria. For example, for many pollutants where EPA criteria guidance
has not been issued, information is available which would be useful in
determining a protective water quality criterion. Sources of such
information include relevant scientific literature, EPA's Integrated
Risk Information System (IRIS), EPA's Aquatic Toxicity Database
(AQUIRE), a database of high quality aquatic life toxicity data (under
development), and other sources.
Request for Comment on State or Tribal Derived Criteria
EPA requests comment on the following question:
1. Would changes to the water quality standards regulation or
development of additional guidance assist State or Tribal efforts to
derive criteria? What changes or guidance would be most helpful?
6. Water Quality Criteria for Priority Pollutants
EPA has not revised the water quality standards regulation to
incorporate CWA section 303(c)(2)(B) which was added to the CWA in
1987. EPA has, however, issued guidance on how States and Tribes may
comply with section 303(c)(2)(B). The ``Guidance for State
Implementation of Water Quality Standards for CWA Section
303(c)(2)(B):December, 1988'' provides three options for compliance:
Option 1 States and Tribes may adopt Statewide or Reservation-wide
numeric chemical-specific criteria for all priority toxic pollutants
where EPA has issued CWA section 304(a) criteria guidance.
Option 2 States and Tribes may adopt numeric chemical-specific
criteria for those stream segments where the State or Tribe
determines that the priority toxic pollutants for which EPA has
issued CWA section 304(a) criteria guidance are present and can
reasonably be expected to interfere with designated uses.
Option 3 States or Tribes may adopt a chemical-specific translator
procedure that can be used to develop numeric criteria as needed.
The phrase ``translator procedure'' in this context means a method
for translating a State's or Tribe's narrative toxics criterion into
chemical-specific, numeric criteria sufficient to comply with CWA
section 303(c)(2)(B). As discussed in EPA guidance (``Guidance for
State Implementation of Water Quality Standards for CWA Section
303(c)(2)(B),'' December 1988, Notice of Availability at 54 FR 346,
January 5, 1989), such translator procedures generally identify the
equations, protocols, and data sources that are used to translate
narrative criteria into derived chemical-specific criteria. Such
translator procedures are different from the narrative criteria
implementation procedures required in 40 CFR 131.11(a)(2) of the water
quality standards regulation in that such implementation procedures
must be adopted into the State's or Tribe's regulations and generally
describe all mechanisms that are used and integrated to attain
narrative criteria, including chemical-specific, whole effluent
toxicity, and biological methods (see the discussion of narrative
criteria implementation procedures in sub-section (c)(6) above). EPA
believes that revisions to the water quality standards regulation to
incorporate the CWA section 303(c)(2)(B) requirements would enhance
public understanding of EPA's implementation of the provision.
EPA's guidance on CWA section 303(c)(2)(B) established a
presumption that any information indicating that such pollutants are
discharged or present in surface waters (now or in the future) may be
considered sufficient justification to require adoption or derivation
of numeric criteria. The guidance made clear that the requirement to
adopt (or derive) criteria applies not just to pollutants that are
already affecting surface waters, but also to pollutants that have the
potential to affect surface waters in the future. The rationale for
this approach is that it is important to have numeric criteria applied
to waters where current or future activities may result in sources of
priority toxics that warrant regulatory controls or other pollution
abatement or assessment activities. This interpretation of section
303(c)(2)(B) is now reflected in EPA guidance included in the Technical
Support Document (TSD) for Water Quality-Based Toxics Control (TSD) and
the Water Quality Standards Handbook (see page 30 in the TSD).
In implementing CWA section 303(c)(2)(B), many States and Tribes
have adopted statewide or reservation-wide criteria for all priority
toxics where EPA has issued CWA section 304(a) criteria guidance.
Taking this approach eliminates the need to determine whether a
``reasonable expectation'' for use interference exists on a water body-
by-water body basis, and thus greatly simplifies the process for
establishing numeric criteria for priority toxics. In other States and
Tribes, however, broad application of numeric criteria for priority
toxics has not occurred, and the ``reasonable expectation'' question
has been a significant implementation issue. EPA is considering whether
its existing guidance on this issue is adequate to support equitable
decisions nationally.
Another issue stemming from CWA section 303(c)(2)(B) implementation
concerns the State or Tribe option to develop a ``translator
procedure'' to achieve compliance. In EPA's CWA section 303(c)(2)(B)
guidance, this approach was described as Option 3. The guidance
intended to be used are the 1980 Human Health Guidelines and 1985
Aquatic Life Guidelines. All of which have been both peer reviewed and
publicly reviewed and thus meet the requirements of ``scientific
defensibility'' under 40 CFR 131.11.
Although EPA believes that adoption of such chemical-specific
translator procedures potentially provide a State or Tribe with a
useful means of establishing criteria, there are several issues
associated with the use of such procedures. For example:
(1) It may be difficult for the public to stay abreast of the
current applicable criteria where a State or Tribe does not routinely
publish an updated list of State or Tribe criteria and provide wide
distribution.
(2) Public participation may occur primarily on the details of the
procedure itself, rather than the pollutant-specific criteria resulting
from application of the procedure.
(3) Without requirements to submit to EPA for review and approval
the individual criteria generated using the translator procedure, there
could be a tendency to not include such criteria in the State's or
Tribe's water quality standards at the time they are generated.
A third issue that arises from State and Tribal efforts to
implement CWA section 303(c)(2)(B) concerns the provision for priority
toxic pollutants that are not the subject of CWA section 304(a)
criteria guidance. Where such numeric criteria guidance is not
available, and where necessary to protect the designated uses, CWA
section 303(c)(2)(B) provides that when a State or Tribe (1) reviews
Water Quality Standards or (2) revises or adopts new standards pursuant
to this paragraph, States and Tribes are to adopt criteria based on
biological monitoring or assessment methods.
When adopting criteria based on biological monitoring or assessment
methods, States and Tribes currently
[[Page 36767]]
have considerable latitude to devise an approach to satisfy the
requirement. For example, States and Tribes may establish ambient
criteria for the parameter toxicity. Alternatively, States and Tribes
could adopt narrative biological criteria. Clearly, a variety of
approaches, representing a range of resource commitments, may be used
to satisfy this requirement. All of these approaches must meet the test
of ``scientific defensibility'' and be consistent with the goals of the
CWA.
Request for Comments on Water Quality Criteria for Priority Pollutants
EPA seeks public comment on the following questions:
1. With regard to compliance with section CWA section 303(c)(2)(B),
would it be better to include only a general requirement, such as one
which repeats the language in the statute itself, or should the
regulation reflect EPA's interpretation of the options to achieve
compliance with the provision?
2. Have problems or issues arisen in the implementation of CWA
section 303(c)(2)(B) that may need to be addressed by changes in the
regulation or revised EPA guidance?
3. What factors should be considered in determining whether a
``reasonable expectation'' for use interference exists? How has the
``reasonable expectation'' threshold decision been interpreted and
addressed by the States or Tribes? Does EPA need to clarify when a
``reasonable expectation'' for use interference exists, and if so,
should the Agency clarify the requirement by issuing additional
guidance, by issuing regulatory requirements, or a combination of the
two approaches?
4. Where a State or Tribe adopts a chemical-specific translator
procedure for derivation of numeric criteria, what process should the
State or Tribe follow to ensure that notice of State derived criteria
is provided to the public?
5. Should EPA require States or Tribes using translator procedures
to publish an updated list of criteria for all water bodies?
6. Should EPA revise the regulation to explicitly require that,
where a translator procedure is used to derive criteria, public
participation is required for each individual criterion, even where an
opportunity for public participation was previously provided when the
procedure itself was adopted?
7. Should submission of each criterion derived using translator
mechanisms for review and approval or disapproval be a requirement,
even where EPA previously reviewed and approved the procedure itself?
If so, should implementation of derived criteria (e.g., in NPDES permit
renewal and development) proceed even where EPA has not yet issued an
approval/disapproval decision?
8. Does this statutory provision need to be further clarified and
interpreted by the Agency? Should changes to the water quality
standards regulation or Agency guidance be pursued?
7. Criteria for Non-Priority Pollutants with Toxic Effects
Over the years, an issue which has periodically arisen,
particularly for non-priority pollutants, has been the proper approach
to identifying the circumstances for which adoption of numeric criteria
is required. Currently, the regulation does not elaborate on how this
question should be addressed; it only provides the general mandate to
adopt criteria ``sufficient to protect uses.''
EPA's current thinking is that the regulation should probably be
modified to further specify the circumstances under which numeric
criteria for non-priority pollutants must be adopted. One approach
would be to model the requirements for non-priority pollutants after
the requirements included in CWA section 303(c)(2)(B) for priority
pollutants. That is, for non-priority pollutants where EPA has issued
criteria guidance, the regulation could require adoption of numeric
chemical-specific criteria where the discharge or presence of the
pollutant can reasonably be expected to interfere with designated uses.
EPA could define ``reasonable expectation'' broadly to support adoption
of criteria before new pollution sources are proposed, or more narrowly
for non-priority pollutants, limiting such a requirement for adoption
of criteria to only those water bodies and pollutants where uses are
already being interfered with, or where pollution sources now exist or
are certain to occur in the near future. Establishing Such a
requirement would encourage development of criteria for commonly-
discharged and highly toxic pollutants like ammonia and chlorine that
are currently not considered priority pollutants under section 307(a)
of the CWA.
Strengthening the requirements for adoption of criteria for non-
priority pollutants would address a concern of some that many of the
CWA section 307(a) priority pollutants are no longer an appropriate
focal point for State, Tribe and EPA toxic control efforts (e.g., some
of the pesticides included on that list are no longer in widespread
use).
Request for Comments on Criteria for Non-Priority Pollutants With Toxic
Effects
EPA seeks public comment on the following questions:
1. For what specific pollutants and under what circumstances should
adoption of criteria for non-priority pollutants be required by
regulation?
2. Should EPA amend the water quality standards regulation or issue
additional guidance to clarify when adoption of numeric chemical-
specific criteria for non priority pollutants is necessary to ``protect
designated uses''?
3. Should EPA require States or Tribes to adopt narrative criteria
and a narrative criteria translation method for both 307(a) and other
pollutants which elicit toxic effects on organisms?
8. Criteria Where Data or Guidance is Limited
A key issue facing States and Tribes seeking to develop aquatic
life and human health criteria concerns the data requirements necessary
to support derivation of a criterion. (In developing national CWA
section 304(a) criteria guidance, EPA has established minimum data
requirements.) When sufficient, acceptable data are not available,
however, many States and Tribes have resorted to adoption of lowest
observed effect levels (LOELs) as criteria in order to ensure that some
level of protection is in place. LOELs are based on the lowest observed
concentration of a chemical at which a statistically significant
adverse effect was observed in an aquatic test organism. However, EPA
would counsel against adoption of water quality criteria based on LOELs
alone because they may not ensure protection of aquatic life uses
since: (1) they represent effect concentrations, and (2) there may be
significant limitations in the database upon which they are supported.
Thus, if this approach is used, States and Tribes are encouraged to
use safety factors to approximate better a protective water quality
level. The particular safety factor employed generally depends on the
amount and quality of data concerning the LOEL. EPA has approved this
approach in particular instances because criteria based on such LOELs
provide more protection than no criteria at all.
A better approach to developing values with sparse data was
developed and promulgated by EPA as part of the Water Quality Guidance
for the Great Lakes System (Great Lakes Guidance). Under that
Guidance's Tier II procedure, States and Tribes derive values to
interpret the narrative criteria for
[[Page 36768]]
pollutants where the minimum data requirements for derivation of a
criterion are not satisfied (see appendix C of 40 CFR Part 132.) These
values are then used in place of the absent criteria as the basis for
NPDES permit limits where needed. EPA's current thinking is that this
approach for establishing values for interpreting the narrative for
pollutants where data are limited is preferable to adoption of criteria
based on a LOEL.
The Tier II methodology in the Great Lakes Guidance is designed to
be used in the absence of the full set of data needed to meet criteria
data requirements. For pollutants for which criteria have not been
adopted into State or Tribal water quality standards, Great Lakes
States must, under the guidance, use methodologies consistent with
either the criteria (GLI Tier I) or Tier II methodologies, depending on
the data available to implement their existing narrative water quality
criteria that prohibit toxic pollutants in toxic amounts in all waters.
In adopting the Great Lakes Tier II methodology, EPA, working with
the States, determined that there is a need to regulate pollutants more
consistently in the Great Lakes System when faced with limited data on
which to base criteria. Many of the Great Lakes States are already
employing procedures similar to the approach in the final Guidance to
implement narrative criteria. EPA determined the Tier II approach
improves upon existing mechanisms by utilizing all available data. The
Tier II aquatic life methodology is used to derive Tier II values which
can be calculated with fewer toxicity data than under the Tier I water
quality criteria methodology. Tier II values can, in certain instances,
be based on toxicity data from a single taxonomic family, provided the
data are acceptable. The Tier II methodology generally produces more
stringent values than the Tier I criteria methodology, to reflect
greater uncertainty in the absence of additional toxicity data. As more
data become available, the derived Tier II values tend to become less
conservative. That is, they more closely approximate Tier I numeric
criteria.
States and Tribes may also develop their own criteria derivation
procedure under option 3 of EPA's CWA section 303(c)(2)(B) guidance for
priority toxic pollutants. This approach allows for timely derivation
of criteria based on the latest available data, and may be used to
derive criteria for pollutants for which EPA has not issued guidance.
However, as for all criteria, such a procedure would need to result in
criteria that are scientifically defensible, so again the issue of
minimum data requirements is important.
Request for Comment on Criteria Where Data or Guidance is Limited
EPA requests comment on the following questions:
1. Should adoption of a lowest observed effect concentration be
considered an acceptable option where no other criteria guidance is
available, or should use of an uncertainty factor (e.g., 0.1, 0.5) be
required to better approximate a protective water quality level? If an
uncertainty factor is used, should that factor vary based on the amount
and quality of data used to drive the LOEL? If so how?
2. Should EPA develop a method for derivation of alternative values
for pollutants where the minimum data requirements included in EPA's
criteria guidelines are not satisfied, such as the tier 2 procedure in
EPA's Water Quality Guidance for the Great Lakes System?
3. How applicable should the Tier 2 process be to States and Tribes
outside of the Great Lakes? Does the regulation need to be modified to
include Tier 2 specifically for the entire country?
4. Does the information included in EPA's toxicity databases (e.g.,
IRIS, AQUIRE) need to be made more accessible to States, Tribes, or
others seeking to develop their own criteria? If so, how can this be
accomplished?
9. Toxicity Criteria
Toxicity criteria are an additional type of water quality criteria
used to protect aquatic life. Toxicity criteria are expressed in terms
of ``toxic units'' that cause toxic effects to aquatic organisms and
are determined by exposing aquatic organisms to water samples (e.g.,
ambient water or effluent discharges). Whole effluent toxicity (WET)
testing can be effective for controlling discharges containing multiple
pollutants. It can also provide a method for addressing synergistic and
antagonistic effects on aquatic life.
EPA is considering revising the water quality standards regulation
to require States and Tribes with water quality standards authority to
develop a numeric quantification of acceptable surface water levels for
the parameter ``toxicity.'' Doing so would implement the narrative
criteria that waters be ``free from'' toxics in toxic amounts.
Currently, States and Tribes use various approaches to implementing
their narrative criteria, including using numeric toxicity values and
implementing them through NPDES permits. However, there is no current
requirement for States or Tribes to specify numeric criteria for
toxicity in their water quality standards. Under current requirements
and guidance, States and Tribes do not always specify implementation of
toxicity criteria and test methods as a required means to implement the
narrative water quality criteria.
Toxicity is commonly measured by exposing test organisms (e.g.
Ceriodaphnia, Fathead minnow) to various concentrations of chemicals or
chemical mixtures in water. EPA has promulgated methods for measuring
aquatic toxicity in effluents and surface waters in 40 CFR Part 136.
EPA provided a recommendation on the allowable magnitude of this
parameter in the 1991 Technical Support Document for Water Quality-
based Toxics Control (TSD) that would facilitate State or Tribal
implementation of such a requirement. The recommendation reads: For
protection against acute toxicity, ``the criterion maximum
concentration (CMC) should not exceed 0.3 acute toxic units to the most
sensitive of at least 3 test species; for chronic protection, the
criterion continuous concentration (CCC) should not exceed 1.0 chronic
toxic units to the most sensitive of at least 3 test species.'' Such a
quantification serves, in conjunction with numeric criteria for
individual pollutants and biological criteria, to establish an
integrated and fully protective basis for assessment and control of
pollutants.
Request for Comment on Toxicity Criteria
EPA seeks public comment on the following question:
1. Should the regulation be modified to explicitly require States
and Tribes to adopt numeric toxicity criteria, or alternatively to use
toxicity values and test methods as a required means to interpret and
implement the narrative criteria? Or, is the current practice
acceptable, whereby some States or Tribes have numeric toxicity
criteria, some utilize toxicity methods to interpret their narrative
requirements of no toxics in toxic amounts, and others use toxicity
mainly as a tool to assess effluent quality, but not as the basis for
permit limits?
10. Sediment Quality Criteria
Sediment quality criteria (SQC) are being developed by EPA pursuant
to sections 304(a)(1) and 118(c)(7)(C) of the CWA in recognition that
many water bodies are not meeting water quality goals even though
ambient water quality criteria are being met. (See ``The Incidence and
Severity of Sediment Contamination in Surface Waters of the
[[Page 36769]]
United States, Volume 1: National Sediment Inventory,'' Office of
Science and Technology, September 1997, EPA-823-R-97-006.) The
contaminants of interest are those that preferentially partition to
sediments, become sequestered, and remain bioavailable to the aquatic
community. SQC are intended to protect against chronic effects to
benthic organisms resulting from sediment contamination. The
development and implementation of SQC is intended primarily to enable
development of pollutant-specific State standards and NPDES permit
limits needed for implementation of a more effective source control
program. In addition, SQC will be useful in other programs, such as
developing clean-up levels for sediment remediation activities and in
evaluating sediments dredged from the Nation's waterways.
Sediment quality criteria have been proposed for five non-ionic
organic compounds: acenapthene, dieldrin, endrin, fluoranthene, and
phenanthrene. See, Technical Basis for Deriving Sediment Quality
Criteria for Nonionic Organic Contaminants for the Protection of
Benthic Organisms by Using Equilibrium Partitioning (EPA-822-R-93-011);
Acenapthene (EPA-822-R-93-013); Dieldrin (EPA-822-R-93-015); Endrin
(EPA-822-R-93-016); Fluoranthene (EPA-822-R-93-012); Phenanthrene (EPA-
822-R-93-014). In addition to non-ionic organic compounds, the Agency
also is working to develop SQC for metals. After considering public
comments, EPA intends to publish final SQC dieldrin and aldrin in final
form. The proposed criteria for acenapthene, fluoranthene, and
phenanthrene will not go final; instead, EPA plans to propose a total
PAH sediment criterion. In addition to its work on SQC, the Agency also
is working to develop standardized methods for performing chronic
sediment bioassay tests.
The EPA Science Advisory Board subcommittee reviewing SQC for non-
ionic organics concluded that: ``these criteria not be used as stand-
alone, pass-fail values for all applications.'' (EPA-SAB-EPEC-93-002).
EPA is developing a users manual to provide guidance on use of SQC in a
regulatory context to ensure consistency with that recommendation. The
guidance would recommend that SQC be used in conjunction with chronic
sediment bioassay tests in determining compliance with State standards,
such as in interpreting the narrative criterion of no toxics in toxic
amounts. Such an approach is currently being developed in more detail,
and the users guidance will be made available to the public for comment
prior to being finalized.
Request for Comment on Sediment Quality Criteria
EPA seeks public comment on the following questions:
1. Should the current regulation be revised to specifically address
sediment quality criteria, and if so, what should such revisions
address?
2. What chemicals or classes of compounds should receive priority
for development of SQC?
11. Biological Criteria
Biological Integrity, Assessments and Criteria '
The Clean Water Act directs EPA to work with States and Tribes to
restore and maintain the biological integrity of the Nation's surface
waters (CWA 101(a), 303, 518(e)). Biological integrity is defined as a
balanced, integrated, adaptive community of organisms having a species
composition, diversity, and functional organization comparable to that
of the natural habitat of a region (Karr and Dudley, EPA-440/5-90-004,
1981). Biological integrity does not necessarily represent an aquatic
system untouched by human influence, but does represent one that is
balanced, adaptive and reflects natural evolutionary processes.
Designated uses and criteria to protect those uses in State and Tribal
water quality standards programs provide the means to achieve
biological integrity.
To more fully protect aquatic resources and provide more
comprehensive assessments of aquatic life use attainment, it is EPA's
policy that States and Tribes should designate aquatic life uses for
their waters that appropriately address biological integrity and adopt
biological criteria necessary to protect those uses (EPA-823-B-93-002,
Office of Water Memorandum to EPA Regions, Policy on Bioassessment and
Biological Criteria, 1991). Designated uses to support aquatic life can
cover a broad range, or continuum, of biological conditions with some
waters being closer to the ideal of biological integrity than others.
The attainable levels of biological integrity for any water is a State
and/or Tribal determination involving public participation.
For example, the State of Maine used the water quality
classification law to establish the minimum standards for three levels
of biological integrity. These levels correspond to the water quality
classification system and are increasingly restrictive, proceeding from
the minimum state standard, Class C, to Class A, the most protective
standard. These refinements serve to explicitly specify the designated
aquatic life uses that apply to each classification category. Class C
requires that the structure and function of the biological community be
maintained and provides for the support of all indigenous fish species.
The intermediate standard of Class B requires that there be no
detrimental changes to the aquatic community, that all indigenous
species are supported and that habitat be unimpaired. The Class A
standard requires that aquatic life be ``as naturally occurs'' and
habitat be characterized as ``natural.'' Within Class A, there is even
a subset, Class AA, that further specifies ``free-flowing'' habitat.
Waters with the Class AA designation are protected from any additional
discharge or alteration. Under this system, attainment of the aquatic
life classification standards for a given water body is evaluated using
numeric biological criteria that were statistically derived from a
statewide database. The numeric biological criteria are slated to go to
rule-making in 1998.
Biological assessments are used to evaluate the condition of a
water body using direct measurements of the resident biota in surface
waters. Biological assessments integrate the cumulative impacts of
chemical, physical, and biological stressors on aquatic life.
Biological criteria, derived from biological assessment information,
can be used to define State and Tribal water quality goals for aquatic
life by directly characterizing the desired biological condition for an
aquatic life use designation. Biological criteria are narrative
descriptions or numerical values that describe the reference condition
of the aquatic biota inhabiting waters of a specific designated aquatic
life use (EPA-440/5-90-004). Biological criteria are based on
integrated measures, or indices, of the composition, diversity, and
functional organization of a reference aquatic community. The reference
condition describes the attainable biological conditions for water body
segments with common characteristics within the same biogeographic
region. In summary, biological criteria provide a direct measure of the
desired condition of the aquatic biota. This capability serves a dual
purpose--goal setting and environmental impact analysis. Biological
assessments are then conducted to evaluate if a water body is attaining
its designated aquatic life use.
Biological criteria can play an important role in water quality
programs and when properly implemented, complement and support
[[Page 36770]]
other methods and criteria, such as chemical water quality criteria and
whole effluent toxicity criteria. The latter are measures, or
indicators, of environmental stress and exposure whereas the biological
assessments and criteria measure the cumulative effects of stressors on
the aquatic community, whether chemical, physical or biological
stressors, singly or in combination. A water quality program that
employs the full array of methods and criteria will develop the
information needed for more accurate assessment of impairment and
effective resource management.
The linkage of biological effects, stressor identification and
exposure assessment is particularly important when there are multiple
stressors impacting a water body, especially when a watershed
management approach is taken, or where wet weather flows are a major
source of impairment in the water body. A comprehensive water quality
program with biological, chemical, toxicity, and physical components
will enable States and Tribes to make better decisions and focus
limited resources to maximize environmental gain. A critical issue
facing EPA's National Water Program is the manner and extent to which
biological assessments and criteria should be incorporated into water
quality programs to transition to a more comprehensive water quality
control program that will better identify impairments and track
improvements. This includes integrating biological assessments and
criteria into use designations and attainability analyses, watershed
management strategies and source control requirements.
Biological criteria typically include measures of the types,
abundance, and condition of aquatic plants and animals, providing
information on the status and function of the aquatic community in
response to the cumulative impact of both chemical and nonchemical
stressors. For example, Ohio uses a multi metric approach to develop
numeric biological criteria for two different assemblages: benthic
macro invertebrates (bottom dwelling insects, etc.) and fish (Yoder,
1995). Biological indices have been derived that integrate measurable
structural and functional characteristics of the in-stream fish and
macro invertebrate communities which help assess the health of the
community. Structural characteristics are based on measures of
biological community structure such as diversity or taxa richness (e.g.
total number of taxonomic groups) and the representation of specific
taxonomic groups (e.g. number of mayfly or caddisfly taxonomic groups)
within the community. Functional characteristics include measures of
biological function such as feeding strategy (e.g. percent carnivores,
omnivores), environmental tolerance (e.g. number of intolerant and
tolerant species), and disease symptoms (e.g. percent diseased species
and anomalies, including deformities, eroded fins, lesions and external
tumors in fish).
The Ohio biological criteria were developed based on ecoregional
reference conditions and provide a quantitative biological description
of the State's designated aquatic life uses for warm water rivers and
streams, including exceptional, general, modified and limited warm
water habitat. The description and derivation of the indices and
ecoregions are contained in the ``Biological Criteria for the
Protection of Aquatic Life: Volume II. Users Manual for Biological
Field Assessment of Ohio Surface Waters'' cited in Ohio's Water Quality
Standards. Ohio uses biological criteria to support all aspects of its
water quality management program (Yoder, 1995). Ohio's approach is
another example of how a State can adopt biologically-based refined
designated aquatic life uses and biological criteria consistent with
EPA's policy.
Application of Biological Assessments and Criteria in State and Tribal
Water Programs
Biological assessments and criteria can be an important component
of State and Tribal watershed management programs by assisting in
prioritization and targeting of actions, setting restoration goals and
performance standards, and documenting results. For example, North
Carolina has adopted narrative biological criteria into its water
quality standards regulation that references standardized methods for
data collection and analysis for fish and macro invertebrate
communities. Specific biological indices, metrics, or numeric criteria
are not included in the water quality standards regulation. However, by
citing the standardized methods in the State's water quality standards,
North Carolina established a mechanism for consistent, quantitative
translation of the narrative biological criteria. Under the State's
five year basin-wide management program, benthic macro invertebrate and
fish community data are presented in individual basin-wide assessment
reports. Macroinvertebrate and fish community surveys, special studies,
and other water quality sampling activities are conducted in the second
and third years of the cycle to provide information for assessing
status and trends through the basin. Water quality management plans are
being developed for all of the State's major river basins on five year
cycles.
Biological assessments and criteria can fulfill several assessment
functions within the NPDES permitting process. In conjunction with
pollutant concentration and toxicity data, biological assessments can
be used to detect previously undetected chemical water quality problems
and to evaluate the effectiveness of control actions. Biological
findings of use impairment can trigger the necessary technical
investigations which can identify the source or sources of impairment
and determine appropriate corrective measures through point or nonpoint
source controls as appropriate. The State of Maine uses biological
assessments and criteria to evaluate the effectiveness of controls and
to inform the permit review process. Aquatic life criteria are
specified in the water quality classification law and attainment is
assessed using quantitative data and a multi variate statistical model.
Findings of biological impairment trigger management intervention to
identify possible causes. Permits have been modified and enforcement
actions initiated to address biological impacts. Alternatively,
favorable biological findings have been used in a tiered approach to
re-direct limited agency and permittee resources to more urgent
concerns.
In Maryland, investigators use bioassessments as an integral part
of the Rapid Stream Assessment Technique (RSAT) to conduct watershed-
wide stream quality reconnaissance, rapid screening of general storm
water BMP performance and for elucidating general watershed land use--
stream quality relationships (Galli, J., 1997). In Michigan, biological
assessments have been used in the Wayne County Rouge River National Wet
Weather Demonstration Project to identify impacts and to guide
decision-makers and the public in evaluating options for preventing,
reducing and minimizing pollution loading impacts on the river under a
watershed approach to wet weather pollution management (Cave, 1997).
Biological assessments and criteria can be useful in evaluating
highly variable or diffuse sources of pollution such as storm water
runoff. These types of point source pollution do not lend themselves
well to traditional chemical water quality monitoring and a biological
assessment of their cumulative impact may effectively evaluate these
discharges and the success of control actions.
[[Page 36771]]
Bioassessments have been successfully used in Florida to assess the
cumulative impacts of multiple pollution sources within a watershed, in
particular, storm water runoff and other nonpoint source discharges
(McCarron, Livingston and Frydenborg, 1997). The Florida Storm water/
Nonpoint Source Bioassessment Projects have found that bioassessments,
over time, help reflect impacts from the fluctuating environmental
conditions and highly variable pollutant inputs of wet weather
discharges. Bioassessments also help to evaluate the habitat
degradation typically associated with Storm water discharges.
Bioassessments were also identified by key storm water experts from
across the Nation as an important environmental indicator tool for
assessing the impacts of storm water runoff and the effectiveness of
storm water management strategies (Claytor and Brown, 1996).
When attempting to identify the specific sources of use impairment
(stressors), the role that biological assessments and criteria will
play needs to be carefully defined. Stressor identifications based
solely on biological information may be straightforward in certain
water bodies where a single source is the cause of impairment. In these
cases, paired bioassessments, conducted above and below the discharge
point, or in the vicinity of the source, may readily identify the
degree of impairment and the efficacy of chosen control strategies. In
small urban watersheds, dominated by storm water runoff, bioassessments
and criteria may provide a direct means to measure and control the
storm water impacts.
However, in complex water bodies, where numerous sources contribute
to the observed biological impairment, it may be difficult for
bioassessments to distinguish the relative degrees of impairment from
each contributing source. Given these situations, EPA anticipates that
a stressor identification evaluation (SIE) procedure will need to be
developed to provide the technical tools and information that watershed
managers can use to identify and evaluate the different sources of
impairment that the bioassessments reveal and the specific stressors
associated with each source (e.g. flow, turbidity, temperature, metals,
etc.).
Guidance on Development of Biological Criteria
EPA has developed and will continue to develop technical guidance
on conducting bioassessments and developing biological criteria for the
following specific water body types: streams and wadable rivers, lakes
and reservoirs, estuaries and near coastal waters, wetlands and large
rivers. Technical guidance for streams and small rivers biological
assessments and criteria was published in 1996 (EPA 822-B-96-001).
Publication of technical guidance on lakes and reservoirs is expected
in 1998 followed by guidance on estuaries and near coastal waters by
1999. Technical guidance development for wetlands was initiated in 1997
and for large rivers in 1998. Completion of these documents is planned
within 5 years.
Guidance on Implementation of Biological Criteria
EPA is currently considering how to best advance State and Tribal
adoption and implementation of biological criteria. A draft discussion
document on implementation of biological criteria by States and Tribes
sets forth an iterative, step-wise approach to development of
biological criteria and adoption in State and Tribal water quality
standards. (draft guidance document on biological criteria
implementation, EPA, March 1998) Elements of a stepwise approach could
include:
(1) establishment of a long term goal to restore and maintain
biological integrity of State or Tribal surface waters where determined
feasible;
(2) implementation plan for development of biological criteria for
specific water body types, including time frame;
(3) development of standardized biological assessment methods,
regional reference conditions, and biological database to support
refinement of designated aquatic life uses and development of
biological criteria;
(4) adoption of narrative biological criteria into water quality
standards;
(5) adoption of quantitatively-based biological criteria in water
quality standards.
In developing a flexible, stepwise approach, EPA is evaluating
options for adoption of biological criteria that would result in the
consistent translation of narrative biological criteria into numeric
criteria (e.g. quantitatively-based biological criteria). A
quantitatively-based biological criteria could be defined as:
(1) A narrative statement adopted into State or Tribal water
quality standards that describes specific designated aquatic life uses
and cites technical procedures existing outside of regulation. The
technical procedures result in the translation of the narrative
statement into quantitative measures; including description of how
biological assessment data is collected and analyzed, and how the
biological criteria are developed.
--and/or--
(2) A narrative statement as above plus the adoption of the
technical procedures or the actual numeric biological criteria in State
or Tribal water quality standards.
These two options for adopting quantitatively-based biological
criteria are based on existing State models such as Maine, North
Carolina and Ohio (EPA 230-R-96-007). North Carolina has adopted a
narrative biological criteria for its aquatic life use classification
and cites in the water quality standard regulation the standardized
methods for data collection and analysis. Maine and Ohio have developed
more refined classifications of their aquatic life uses and developed
biological criteria for each specific use. Both States cite technical
manuals specifying standardized methods. Ohio has adopted its numeric
biological criteria directly into its standards regulation. As
mentioned earlier, the Maine Department of Environmental Protection is
currently embarking on a rule making process to adopt its existing
standardized field methods, statistical analysis protocols and numeric
classification criterion (numeric biological criteria) into its water
quality regulation. Similar to Ohio, these rules will codify the
technical procedures for determining attainment of aquatic life use
classification. EPA describes these various States' work for
consideration as possible models of biological criteria that would
result in the consistent translation of narrative biological criteria
into numeric criteria (e.g. quantitatively-based biological criteria).
A Regulatory Requirement for Biological Criteria
EPA is considering whether it should explicitly require States and
Tribes to adopt biological criteria in either the narrative or numeric
form, and, if not, whether an alternative approach to encouraging the
use of biological criteria is appropriate. Some States and Tribes have
already allocated resources to biological criteria development because
a regulatory requirement is anticipated at some time in the future.
Others have been unwilling to commit resources to development of
biological criteria before specifically required to do so. Concerns
have also been raised about yet another regulatory requirement to be
imposed over existing requirements that are still not fully
implemented--adding new layers of requirements in a piecemeal fashion
without adequate resources. EPA is sensitive to the concern that
[[Page 36772]]
generating the data and developing the analytical capacity to
incorporate biological criteria into water quality standards may
present a significant resource challenge to some States and Tribes.
Advocates for a requirement for States and authorized Tribes to
adopt biological criteria argue that States and Tribes will not
implement biological criteria in a timely manner, if at all, without an
explicit Federal regulatory requirement. The viewpoint has been
expressed that States and authorized Tribes will not adequately
increase program emphasis or resources if biological criteria are not
required and, as a consequence, biological criteria will be relegated
to a lesser role then chemical water quality criteria or whole effluent
toxicity. Some States have either direct (i.e. executive orders,
legislative mandates) or indirect limitations on adopting new
regulations and policies that are more stringent than that required by
Federal legislation. Adopting biological criteria may be seen in some
States and Tribes as exceeding minimum Federal requirements. Concern
has been expressed that without biological criteria as a fundamental
component of a State or Tribal water quality standards program,
transition of water quality standards programs to a more integrated
ecosystem approach with an emphasis on watersheds will not succeed.
Adoption of Narrative Biological Criteria
As an alternative to requiring adoption of numeric biological
criteria, EPA could require States and Tribes to adopt a narrative
biological criteria. The narrative biological criteria could be a
statement of intent adopted in a State's or Tribe's water quality
standards to formally consider the fate and status of aquatic
biological communities and to establish the framework for the
consistent and quantitative translation of a State's or Tribe's
designated aquatic life uses and development of numeric biological
criteria. EPA has published a document on procedures for initiating
narrative biological criteria (EPA-822-B-92-002). An example of a
narrative biological criteria based upon that publication follows:
The State will preserve, protect, and restore the water
resources in their most natural condition deemed attainable. The
condition of these water bodies shall be determined from the
measures of physical, chemical, and biological characteristics of
each surface water body type, according to its designated use. As a
component of these measurements, the biological quality of any given
water system shall be assessed by comparison to a reference
condition(s) based upon similar regional hydrologic and watershed
characteristics (reference standardized methods and operating
protocols).
Where attainable, such reference conditions or reaches of water
courses shall be those observed to support the variety and abundance
of aquatic life in the region as is expected to be or has been
historically found in natural settings essentially undisturbed or
minimally disturbed by human impacts, development or discharges.
This condition shall be determined by consistent sampling and
reliable measures of selected indicated communities of flora and/or
fauna as established by [cite appropriate State agency or agencies]
and may be used in conjunction with acceptable chemical, physical,
and microbial water quality measurements and records judged to be
appropriate to this purpose.
Regulations and other management efforts relative to these
criteria shall be consistent with the objective of preserving,
protecting and restoring the most natural communities of fish,
shellfish, and wildlife attainable in these waters; and shall
protect against degradation of the highest existing or subsequently
attained uses or biological conditions pursuant to State
antidegradation requirement.
EPA is considering what could constitute approvable narrative
biological criteria and the feasibility of EPA promulgating narrative
biological criteria where a State or Tribe fails to adopt such
criteria.
Time Frame for Adoption of Biological Criteria in State and Tribal
Water Quality Standards
In 1991 EPA issued a policy that established as a long-term Agency
goal the development and adoption of biological criteria in State and
Tribal water quality programs (Transmittal of Final Policy on
Biological Assessments and Criteria, memorandum from Tudor Davies,
Director of the EPA Office of Science and Technology, to Regional Water
Management Division Directors, June, 1991). EPA has identified as a
program priority during the FY1997-1999 Water Quality Standards
Triennium that States and Tribes initiate and continue to expand
development of scientifically defensible biological-based
classification systems (FY 1997-1999 Water Quality Standards
Priorities, memorandum from Tudor Davies, Director of the EPA Office of
Science and Technology, July 22, 1996). Based on State experiences,
development of biological criteria can range between five to ten years,
depending on several factors such as available resources, existing
State expertise, existing data bases and geographic variability. If EPA
were to require or recommend that States and Tribes adopt biological
criteria, EPA would need to determine appropriate time frames for
adoption and implementation of these criteria. EPA is considering
whether the following are reasonable and appropriate time frames for
adoption of biological criteria in State and Tribal water quality
programs:
1. narrative biological criteria for streams and an implementation
plan for development of quantitatively-based biological criteria for
streams in the 2000-2003 Water Quality Standards Triennium.
2. narrative biological criteria and an implementation plan for
development of quantitatively-based biological criteria for other
applicable water body types (e.g. lakes and reservoirs, estuaries and
near coastal waters, large rivers and wetlands) within ten years
following EPA publication of technical guidance.
Linkage of Biological Criteria to Stressor-Identification
One of the potential benefits of developing a biological criteria
program is the increased ability to assess water quality impairment due
to nonpoint source pollution, broadening the scope of most water
quality-based programs beyond regulation of effluent discharges.
However, many currently regulated point source dischargers are
skeptical that greater focus on nonpoint source would actually occur,
particularly considering the time and resource constraints on most
State and Tribal programs. Industry and municipalities are concerned
that biological criteria bring an additional layer of regulatory and
associated costs and that they may be an easy target for additional
requirements whether their discharge is the source of impairment or
not. EPA recognizes that the role biological assessments and criteria
will play to help identify specific stressors or sources of use
impairment will need to be carefully defined and is interested in
practical, effective approaches to evaluate potential stressors and
sources of impairment when a water body fails biological criteria.
Request for Comment on Biological Criteria, Assessment and
Implementation
EPA is soliciting comment on the following questions:
1. Should EPA amend the regulation to explicitly require States and
Tribes to adopt biological criteria or are there alternative approaches
that EPA should consider? Should EPA seek to ensure that biological
criteria will be developed and implemented in all State and Tribal
water quality programs?
2. If EPA were to explicitly require States and Tribes to adopt
biological
[[Page 36773]]
criteria, should it require a narrative only, or a combination of both
narrative and numeric criteria as described in the draft implementation
guidance (e.g quantitatively-based biological criteria)? What should
EPA promulgate if a State or Tribe fails to adopt biological criteria
in its water quality standards?
3. If EPA were to explicitly require biological criteria, what is a
reasonable time frame for State or Tribal adoption?
4. What are practical, effective approaches to identify and
evaluate potential stressors and sources of impairment when a water
body fails biological criteria?
5. In what ways can biological criteria and biological assessments
be used to effectively manage known stressors or sources of impairment,
including urban and rural runoff?
12. Wildlife Criteria
Wildlife criteria are designed to protect mammals and birds from
adverse impacts from pollutants due to consumption of food or water
from a water body. A wildlife criteria methodology applicable to the
Great Lakes Basin and a few wildlife criteria were published as part of
the Great Lakes Guidance. EPA does not have an active wildlife criteria
guidance program at this time but it is a potential emerging criteria
program. The wildlife criteria that EPA promulgated in the Great Lakes
Guidance are for the following four chemicals: DDT (and metabolites),
mercury, PCBs, and dioxin (2,3,7,8-TCDD).
Request for Comment on Wildlife Criteria
EPA requests comment on the following question:
1. Does the regulation need to be clarified to specifically address
the development of wildlife criteria guidance for the protection of
aquatic dependent wildlife?
13. Physical Criteria
Physical criteria is a concept that takes into account the physical
attributes of the aquatic environment, such as quality of habitat and
hydrologic balance. Commenters on the draft ANPRM identified physical
habitat and hydrologic balance criteria as additional important forms
of criteria that should be discussed in the ANPRM. EPA agrees that
physical habitat parameters, including flow, are important and often
overlooked parameters that influence and at some sites control whether
or not an aquatic life use is or will be attained. For example,
research referenced by Schueler (see Schueler, T. The Importance of
Imperviousness. Watershed Protection Techniques, Fall 1994) suggests
that in many small urban streams substantial loadings from municipal
separate storm sewer systems are severely degrading the aquatic
habitat. The authors suggest that the primary cause of this habitat
impairment is the high volume and velocity of the storm water flows
into this type of stream. The high flows exceed the peaks in the
natural flow regime of these streams and as a result stream bank
erosion, turbidity and siltation occur and the local habitat is
degraded. Further habitat destruction in larger downstream receiving
waters often results from the physical deterioration of the upstream
urban systems. For example, some recent studies have shown that in some
lakes the biggest source of silt and sediment deposition into the lake
is actually from the eroded material that comes directly out of the
stream bed and stream banks that are scoured out during elevated wet
weather peak discharges and extended hydrographs. This can lead to
eutrophication, increased turbidity, decreased light penetration,
submerged aquatic vegetation (SAV) loss, spawning bed smothering, and
shellfish habitat damage.
Studies of this phenomenon suggest that until these man-made flow
regimes are better managed and the resulting stresses to physical
habitat corrected, no amount of control of pollutants is likely to
restore the aquatic ecosystem to a level more closely resembling a
natural state.
The character of natural waters is obviously affected by wet
weather events. Flowing waters, especially, can change dramatically
with the seasons and in response to specific precipitation events.
Seasonal and event driven changes in flows, sediment loads,
temperature, etc. are common and natural processes which are integral
to the maintenance of natural waters and their aquatic communities.
Human-caused changes to the landscape, however, have altered these
natural processes, and for many waters, the altered flows and the
contamination now associated with wet weather discharges (discharges
that occur in whole or in part as the result of wet weather events)
present significant environmental problems. Although these problems are
generally well recognized, they have been difficult to address
effectively precisely because of their magnitude and variable nature.
The CWA's objectives include the protection and restoration of the
physical integrity of our nation's waters. Scientific experts agree
that overall physical habitat loss is the single biggest factor in the
loss of aquatic species. Physical habitat damage and loss to the
nation's waters includes: (1) Wetlands losses; (2) the denuding of
stream banks through unwise forestry, farming, mining, and
urbanization; (3) the embedding of stream bottoms with fine-grained
silt from poorly designed and managed farm and construction sites; (4)
the damming of river systems; (5) the channelization and/or concrete
lining of rivers and streams; (6) the obliteration of ephemeral and
first-order streams and springs during urbanization and; (7) the
widening and deepening of stream channels due to high-velocity urban
storm flows.
All seven of these phenomena are common forms of aquatic habitat
damage and loss, and yet there is little national guidance to address
the physical parameters that contribute to these impacts. In addition,
EPA does not have a clear picture of how often physical habitat
parameters, including flow are used by States and Tribes to assess,
manage, and/or regulate activities that damage habitat. Some commenters
on the draft asserted that water quality criteria guidance is needed to
address these forms of habitat loss, to create threshold values to
protect designated uses and to provide measuring tools for monitoring
watershed and water body health. EPA agrees that further investigation
of the role of physical habitat parameters, including hydrologic
balance, in water quality standards programs is necessary. EPA is
considering the relative importance of such criteria guidance as
compared to other forms of criteria guidance such as ambient water
quality criteria, sediment criteria and biological criteria; and on the
likelihood that States and Tribes would develop and implement such
criteria if technical guidance and supporting policy were available.
EPA is also interested in identifying examples of where such criteria
guidance has already been used as the basis for assessing, managing and
protecting water quality.
With respect to hydrologic balance, EPA discusses the issue in the
antidegradation section of this ANPRM. Some commenters on the draft
ANPRM suggested that maintaining hydrologic balance in surface waters,
though important in the context of antidegradation, is also important
for other aspects of water quality standards. These commenters
suggested that hydrologic balance should be part of basic water quality
criteria guidance for watershed and water body assessment and for long-
term urban storm water abatement and prevention plans under
[[Page 36774]]
the storm water NPDES program, as well as for the traditional NPDES
program.
EPA is further interested in issues associated with hydrologic
imbalances created by various industries and land operations, and the
options for researching and creating a set of hydrologic balance
criteria guidance. These could include, for instance, regional minimum
stream flow criteria on a seasonal or average monthly basis, a
groundwater-recharge criterion meant to maintain adequate stream base
flow, and a peak-flood and bank full discharge prevention criterion,
perhaps based on hydrologic regions of the country.
Request for Comment on Physical Criteria
EPA seeks comment on the following questions:
1. Would it be useful to explicitly identify physical criteria such
as habitat and hydrologic balance in 40 CFR 131 as a valid form of
criteria that States and Tribes can adopt in their water quality
standards?
2. Would EPA technical guidance on physical criteria be useful to
States and Tribes? Is it necessary?
3. What are some examples of physical criteria that are being used
today and what are they being used for?
4. What should be the principal uses for physical criteria? Would
these help address pulsed or intermittent impacts, such as those from
urban and rural runoff?
14. Human Health
Human health water quality criteria are scientifically derived
values developed by States, Tribes, or EPA to protect human health from
the deleterious effects of carcinogens and noncarcinogenic toxicants.
Human health criteria take into account the health effects from the
consumption of aquatic organisms and drinking water. Human health
criteria are based on the potential of carcinogens and noncarcinogenic
toxicants to cause adverse impacts to human health. When adopting
criteria to protect human health, a State or Tribe may use EPA's
Section 304(a) criteria documents or other information on factors to
derive human health criteria. However, if a State or Tribe decides to
adopt criteria less stringent than recommended by EPA, the State or
Tribe must provide documentation which supports that the approach is
based on sound scientific rationale.
Changes to the Human Health Criteria Methodology are anticipated
for proposal in the Federal Register in 1998. These changes to the 1980
ambient water quality criteria (AWQC) derivation guidelines (45 FR
79347) are intended to reflect the many significant scientific advances
that have occurred during the past 17 years in such key areas as cancer
and noncancer risk assessments, exposure assessments and
bioaccumulation. Comments on any of the key area issues, as well as
implementation issues, are welcome and should be made during the public
comment period following the anticipated 1998 proposal.
The following discussion focuses on three key policy-related
issues, including: choice of risk levels; fish consumption assumptions
and environmental justice, and the use of maximum contaminant levels.
a. Risk Levels. Criteria for specific pollutants for the protection
of human health rely in part on risk levels (incidence of cancer).
Numeric criteria for carcinogens are based on three inter-related
assumptions: exposure, cancer potency, and risk level. Exposure
considerations are based on a wide range of factors, including an
estimate of the rate of fish and drinking water consumption, an
estimate of the body weight of an exposed individual, and an estimate
of the rate of a chemical's relative tendency to bioaccumulate in fish
tissue as compared to the surrounding water. Cancer potency factors
(q1*) provide a measure of a chemical's potential to cause cancer, and
are typically derived from studies on laboratory animals. The risk
level represents an incremental increase in cancer incidences resulting
from exposure to the chemical.
EPA guidance sets forth a range of criteria values that result in
calculated risk levels of 10-5, 10-6, and
10-7 for informational purposes. Most States and Tribes
select either a 10-5 or 10-6 risk level as an
appropriate value, i.e., one additional cancer incidence per one
hundred thousand or one million exposed individuals, respectively. This
level seems to represent some general scientific and public consensus
that the cancer risks are acceptably small or insignificant. States and
Tribes, however, are not limited to selecting among the risk levels
published in the CWA section 304(a) guidance documents.
If exposure assumptions are changed, while the assumed risk level
remains the same, the criterion will change accordingly. The risk to
people who intake more than the default exposure assumptions increases
with the degree of change in the intake rates. For example, if the
State or Tribe chooses to protect at a risk level of 10-5
and assumes a fish consumption rate of 6.5 gm/day, but some individuals
within the State or Tribe actually eat 65 gm/day of fish, the criterion
actually protects those individuals at a risk level of 1 x
10-4 (one additional cancer case per 10,000 people). The
risk level can change based on the relative change in each parameter.
When adopting these standards, States and Tribes are strongly
encouraged to provide documentation that the assumptions made in
establishing the criteria are reasonable and adequately protect the
population, including highly exposed subpopulations at the risk level
asserted in the States' and Tribes' standards. EPA strongly encourages
States and Tribes to highlight these provisions of their standards
during the public participation process.
EPA's current criteria documents indicate the risk level within a
range of 10-5 to 10-7 for the general population.
The policy has been to allow States and Tribes to select appropriate
risk levels and is consistent with the framework of the CWA that
recognizes and supports State and Tribal primacy in making risk
management decisions to protect its population provided that the goals
of the Act are met. EPA's approval of different cancer risk levels to
protect human health in different States or Tribes is subject to
debate. Many have questioned States' and Tribes' selection and EPA's
approval of various risk levels to protect human health. Some assert
that EPA should require all States and Tribes to adopt a single risk
level. Others believe EPA should require States and Tribes to develop
data on the different exposure assumptions that may be present within
the State or Tribe.
With regard to subpopulations that may consume higher amounts of
fish than is assumed for the general population, EPA's Great Lakes
Guidance stated that a risk level of 10-4 for such
subpopulations in the Great Lakes basin can be protective.
In a draft proposal of the water quality criteria methodology
revisions, EPA is considering proposing that risk levels in the range
of 10-4 to 10-6 be adopted in deriving criteria.
However, the proposed revisions also note that care must be taken in
situations where the AWQC includes fish intake levels based on the
general population to ensure that the risk to more highly exposed
subgroups (subsistence, minority) does not exceed the 10-4
risk level. Furthermore, EPA is considering proposing the
10-6 risk level as the level that ensures protection for all
exposed population groups. As stated before, all comments regarding
methodology, including risk levels,
[[Page 36775]]
should be made during the public comment period following the
anticipated 1998 Human Health Criteria Methodology proposal.
EPA intends to foster consistent approaches between Agency program
offices, including its approach to determining allowable risk levels.
The Food Quality Protection Act of 1996 (FQPA) amended the Federal
Food, Drug and Cosmetic Act (FFDCA) to prohibit EPA from issuing
tolerances for pesticide residues in or on food unless the Agency
determined that there is a ``reasonable certainty'' that the residues
will result in ``no harm.'' Tolerances are allowable levels of
chemicals in food; food containing residues in excess of a tolerance
may not be sold in commerce. The legislative history of FQPA indicated
Congressional support for EPA's view that reasonable certainty of no
harm would generally be met when a non-threshold risk is below a
10-6 level. For threshold risks, the legislative history
contained general support for a margin of safety of 100, except that
the Statute required the Agency to add an additional 10-fold margin of
safety to protect infants and children, unless the Agency concluded on
the basis of reliable data that a different margin would be safe for
infants and children. In determining whether dietary exposures are
safe, the FQPA also directs EPA to consider non-occupational exposures
to chemicals used as pesticides, and to aggregate risks from chemicals
that share a common mechanism of toxicity. EPA's Office of Pesticide
Programs is in the process of developing new policies in response to
the FQPA. EPA's Office of Water will consider these policies when they
are completed.
b. Fish Consumption Assumptions. EPA's recommended human health
criteria under CWA section 304(a) guidance are currently derived with a
fish consumption rate of 6.5 grams per day (roughly one quarter ounce
of fish and shellfish). This value represents an average based on
market survey data gathered in 1973-74, and reflects a national average
for all consumers and nonconsumers of fish and shellfish from estuarine
and fresh waters. Again, EPA intends to propose revisions to the human
health methodology for deriving ambient water quality criteria,
including revisions of the fish consumption rate. Some assumptions
regarding fish consumption and criteria policy are also discussed in FR
Vol. 61, No. 239, 65183 (December 11, 1996).
EPA recognizes that, while important, the national fish consumption
estimate is one of many different parameters used to set ambient water
quality criteria to protect human health and that the interactions of
these parameters adds substantial complexity to the methodology.
However, because this component is easily understood, it receives the
most attention from the general public. Overall, EPA considers its
human health criteria methodologies to be conservative and protective
of human health.
EPA also recognizes that there are subpopulations that consume
greater quantities of fish and has considered this as part of the human
health methodology for developing water quality criteria. State and
Tribal human health criteria are often based on a risk level of
10-5 or 10-6 to protect people inclined to
consume higher quantities than the average. In addition, with
regulatory actions for carcinogens, individuals consuming even 20 times
the 6.5 gram amount would still be protected at the 10-4
risk level. (EPA is not proposing a national risk level of
10-4 here, rather EPA is acknowledging that the level of
risk is relative to the consumption of fish (i.e., it is greater for
individuals consuming more fish than the national average).
A similar rationale for the protectiveness of a criterion may not
apply to non-carcinogenic pollutants (i.e., RfD-based chemicals), where
significantly higher fish consumption rates may (when combined with
other exposure sources) result in exposures significantly exceeding the
RfD. Although there are safety factors associated with an RfD, they are
related to uncertainties associated with the toxicological evaluation,
not with the sources and levels of exposure. Therefore, significantly
higher intakes may require more stringent criteria to protect human
health.
EPA is seeking ways to implement Executive Order 12898 (February
16, 1994, 59 FR 7629) regarding environmental justice to ensure that
water quality criteria are developed taking into account populations
such as Native Americans and other minorities, as well as other
subsistence fishers. This would include working with the scientific
community and the public to improve EPA's health assessments and risk
assessments and incorporate relevant issues into its policies and
guidance. This also includes mechanisms for public participation (e.g.,
meetings) for the purposes of fact-finding, receiving comments, and
conducting inquiries concerning environmental justice.
Relevant to water quality standards, EPA recognizes the need to
address issues regarding different fish consumption patterns among
subsistence, minority populations. EPA acknowledges that these groups
may consume a greater quantity of fish than the national average. In
addition, these groups have asserted that States and Tribes should be
required to take a more aggressive role in protecting them.
Guidance for Assessing Chemical Contaminated Data for Use in Fish
Advisories (Vol. 1-IV, USEPA, 1993 and 1994) notes that fish and
shellfish consumption rates vary greatly for sections of the U.S.
population (e.g., by gender, race, age, cultural and recreational
activity, and income levels). Given the wide variations in consumption
patterns, it would not seem to be possible for States and Tribes to
provide the same level of protection from contaminated fish for all
consumers. EPA believes criteria should ensure adequate protection of
all significant populations and subpopulations from reasonable risks.
States and Tribes are encouraged to consider local surveys when
selecting fish consumption rates to protect their populations since the
national average value may not be indicative of local consumption
habits. In its Water Quality Guidance for the Great Lakes System (60 FR
15366, March 23, 1995), EPA included a Great Lakes-specific fish
consumption rate of 15 grams per day. This rate was based on several
fish consumption surveys from the Great Lakes (see 60 FR 15366 at
15374, March 23, 1995.) EPA has also published for external peer review
``Draft Guidance for Conducting Fish and Wildlife Consumption
Surveys.'' (U.S. EPA 1997).
States and Tribes could be encouraged to modify criteria on a site-
specific basis to provide additional protection appropriate for highly
exposed subpopulations. That is, where high-end consumers would not be
adequately protected by criteria derived using the default fish intake
assumption, the State or Tribe may modify this assumption to provide
appropriate additional protection. Again, such a recommendation was
made in the Great Lakes Guidance. This preference will also be stated
in the proposed revisions to the human health methodology for deriving
ambient water quality criteria.
c. Maximum Contaminant Levels. Under the Safe Drinking Water Act
(SDWA), EPA develops chemical-specific numeric values for use in
protecting public drinking water supplies. They are maximum contaminant
level goals (MCLGs) and maximum contaminant levels (MCLs). A MCLG is a
non-enforceable concentration of a drinking water contaminant that is
protective of
[[Page 36776]]
adverse human health effects and allows an adequate margin of safety. A
MCL is the maximum permissible level of a contaminant in water which is
delivered to any user of a public water system. MCLGs are based solely
on human health considerations (i.e., an identified adverse effect to
human health, combined with an exposure intake estimate). In contrast,
MCLs are to be as close to the MCLG as feasible, taking into
consideration the availability and the cost of treatment technologies
as well as the availability of analytical methodologies. When these two
additional factors beyond health (treatment cost and analytical
factors) are considered, the MCL for some chemicals is a higher (i.e.,
less stringent) value than the MCLG. However, there are also many
chemicals for which the MCL is equal to the MCLG. This is particularly
true for noncarcinogens. Over 80% of all current MCLs for
noncarcinogens are identical to the corresponding MCLG for that
substance. For carcinogens, MCLs are always higher than MCLGs because
MCLGs for carcinogens are routinely set to zero.
Some States and Tribes utilize MCLs and MCLGs, as criteria to
protect human health under the CWA. For some chemicals, the MCL or MCLG
is more stringent than CWA section 304(a) human health criteria. In
other cases, CWA criteria are more stringent than the MCL or MCLG.
These differences come about for three basic reasons. First, as noted
above, the 304(a) criteria under the CWA and MCLGs under the SDWA are
strictly health-based values that do not account for treatment costs or
analytical limitations. The MCL, however, does take into account
treatment costs and analytical limitations. Second, the methodologies
used to calculate the 304(a) criterion and the MCLG--both health-based
values--for the same chemical often differ. Third, the MCLG and the
304(a) criterion sometimes have been calculated at different times,
often years apart, using the current risk and exposure information at
the time. Where different information on risk and exposure was used,
differences in the numerical values can be expected.
It is important to consider some of the methodological differences
between the derivation of 304(a) criteria and MCLs and MCLGs. Although
the methods under SDWA and CWA both use the same reference dose (RfD)
or cancer potency slope, and both methods assume a 70 kg adult and
consumption of 2 liters of water per day, there are several important
differences. One difference is that MCLGs for chemicals that are known
or likely carcinogens are usually set equal to zero, while CWA section
304(a) criteria for carcinogens are based on an incremental cancer risk
level and are never set equal to zero. For chemicals with limited
evidence of carcinogenicity, the MCLG is usually based on the
chemical's reference dose (RfD) for noncancer effects with the
application of an additional uncertainty factor of 1 to 10 to account
for its possible carcinogenicity. In contrast, the 1980 CWA section
304(a) criteria guidelines do not differentiate among carcinogens with
respect to the weight of evidence grouping; all were derived based on
lifetime carcinogenic risk levels.
Another important difference between the two methodologies is that
a single determined risk value (single reference dose or single cancer
risk value within the 10-4 to 10-6 range) is used
in setting an MCLG, while CWA section 304(a) criteria have been derived
for each of the three incremental risk levels spanning 10-5
to 10-7, with the decision on which value to adopt left to
the State or Tribe.
Another important methodological difference is in the approach to
accounting for exposure sources. MCLGs for RfD-based chemicals
developed under the SDWA follow a relative source contribution (RSC)
approach in which the percentage of exposure that is attributed to
drinking water is determined relative to the total exposure from all
sources (e.g., drinking water, food, air). The rationale for this
approach is to ensure that an individual's total exposure to a chemical
does not exceed the RfD. To develop CWA human health criteria for
noncarcinogens, the 1980 CWA National Guidelines recommended taking
non-fish dietary sources and inhalation into account. However, data on
these other sources were generally not available. Therefore, it was
typically assumed that an individual's total exposure to a chemical
came solely from drinking water from the water body and consumption of
fish and shellfish living in the water body. Also, CWA criteria are
based on a prediction of exposure from fish and shellfish using a
bioconcentration factor (BCF) to estimate the bioconcentration of the
individual chemical, and a fish/shellfish consumption rate. To date,
under the current MCLG methodology, BCFs have not been used in the
exposure estimates and fish/shellfish consumption rates have been only
marginally accounted for (e.g., via general FDA dietary estimate or
conservative default assumption).
Because of the differences in the approach to exposure and the
basis of toxicity values, the health-based drinking water goal (MCLG)
is sometimes more stringent than the CWA human health criterion (304(a)
criterion). However, the opposite is sometimes true. An example of the
former is 1,4-dichlorobenzene, for which both the MCL and MCLG are 75
ug/L and the 304(a) criterion (for protection of human health from the
exposures of drinking water and consuming contaminated fish) is 400 ug/
L. In this case, the MCLG was developed based on an assumption that 20%
of the total exposure is from drinking water (the RSC factor applied to
this noncarcinogen), whereas the CWA criterion effectively assumes that
non-water exposure is negligible. Additional sources of difference
between the two values are: (1) the BCF/BAF for 1,4-dichlorobenzene is
low and thus does not make the 304(a) value significantly lower; (2)
the MCLG was derived from an RfD of 0.1 mg/kg/day, while the 304(a)
criterion utilized an Acceptable Daily Intake (ADI, now replaced by the
use of RfDs) of 0.013 mg/kg/day; and, (3) the MCLG included a safety
factor of 10,000, whereas the water quality criterion included a safety
factor of only 1,000.
In contrast, for noncarcinogens where the BCF/BAF is high, the CWA
criteria may be roughly equivalent or more stringent than the health-
based drinking water levels because of the considerable exposure via
fish/shellfish consumption that is assumed in deriving the CWA
criteria. As with the previous example, the difference may be
compounded if the toxicological values have a different basis. An
example is endrin, for which the MCL and MCLG are 2 ug/L and the CWA
section 304(a) human health criterion (again, for protection from the
exposures of drinking water and consuming contaminated fish) is 0.76
ug/L. In this case, the drinking water level is, again, developed based
on the RSC assumption of 20%, whereas the CWA criterion assumes that
non-water exposure is negligible. However, the BCF/BAF for endrin is
quite high (3,970) and drives the 304(a) value significantly lower.
Furthermore, the MCLG was derived from an RfD of 3.0 x
10-4 mg/kg/day, while the CWA criterion utilized an ADI of
1.0 x 10-3 mg/kg/day. With endrin, both the MCLG and the
water quality criterion included a safety factor of 100.
Of course as noted above, the MCL takes into account the cost or
availability of treatment technology or analytical methods, and may be
much less stringent than the CWA human health criterion, regardless of
the
[[Page 36777]]
exposure assumptions or toxicological basis (e.g., 1,1,2-
trichloroethane).
Because of the differing methods used to implement the SDWA and the
CWA, EPA has recommended that, where consideration of available
treatment technology, costs, or availability of analytical
methodologies has resulted in MCLs that are less protective than MCLGs
or CWA section 304(a) criteria, States and Tribes should consider using
MCLGs and/or health-based CWA section 304(a) criteria to protect
surface waters that are designated for water supply use under the
State's or Tribe's water quality standards. Furthermore, when adopting
water quality criteria to protect a surface water designated for
drinking water supply use, States and Tribes should carefully consider
what value (e.g., the MCLG or the 304(a) value) provides a defensible
estimate of the water quality level necessary to fully protect the use,
and whether relevant exposure routes have been adequately considered in
the derivation of each value.
EPA stated its policy on the use of Section 304(a) human health
criteria versus MCLs in 45 FR 79318, November 28, 1980. Additionally, a
memorandum from R. Hanmer to the EPA Regional Water Management Division
Directors dated December 12, 1988, provided detailed guidance with
regard to this policy. Specifically, for the protection of public water
supplies, EPA encouraged the use of MCLs. When fish ingestion is
considered an important activity, EPA recommended the use of 304(a)
criteria to protect human health. In all cases, if a 304(a) criterion
did not exist for a chemical, an MCL was deemed a suitable level of
protection.
The forthcoming proposed human health criteria guidelines
(scheduled for publication in 1998 and cited above) are expected to
recommend a slightly different approach. Although EPA considers the use
of MCLs to protect surface waters under the CWA to be acceptable in the
absence of 304(a) criteria, EPA expects to recommend that:
--MCLs only be used when they are numerically the same as the MCLG and
only when the sole concern is the protection of public water supply
sources (e.g., where the chemically toxic form in water is not the form
found in fish tissue and, therefore, fish ingestion exposure is not an
issue of concern);
--where consideration of available treatment technology, costs, or
availability of analytical methodologies has resulted in MCLs that are
different than MCLG values or 304(a) criteria, States and Tribes
consider using MCLGs and/or 304(a) criteria to protect surface waters
designated for water supply use;
--where fish consumption is an existing or potential activity, States
and Tribes ensure that their adopted human health criteria adequately
address this exposure route;
--where fish consumption is a designated use, States and Tribes use
304(a) criteria to protect that use because fish consumption and
bioaccumulation are explicitly addressed by the 304(a) methodology;
--where water monitored at existing drinking water intakes has
concentrations at or below MCLGs, then the water could be considered to
meet a CWA designated use as a drinking water supply and a criterion
reflecting that level could be adopted; and,
--for carcinogens where the MCLG is equal to zero, States and Tribes
base a criteria value at the drinking water intake on an acceptable
cancer risk level (i.e., a level within the range of 10-4 to 10-6), to
protect human health. It is not intended that MCLGs of zero would be
used as the basis for State or Tribal water quality criteria.
As States and Tribes may be more stringent than EPA, States and
Tribes may adopt an MCL or MCLG as a water quality criterion that is
more stringent than EPA's recommended section 304(a) criterion. In
situations where a recommended 304(a) criterion is less protective than
an MCL, EPA expects to recommend in the 1998 human health criteria
methodology proposal use of the MCL instead of the recommended 304(a)
criterion because it would help to ensure adequate source water
protection and avoid costly compliance problems for downstream water
supply utilities.
EPA has considered extensively this issue of equivalency between
the drinking water component of CWA section 304(a) criteria and MCLGs
or MCLs. EPA expects to move toward similar assessment methodologies
(including its exposure and relative source contribution [RSC]
policies) for deriving CWA criteria and MCLGs. Consistent exposure
evaluation methodologies for deriving CWA 304(a) criteria for human
health protection and MCLGs under SDWA, would, over time, eliminate the
need to consider using MCLs for adopting State water quality standards.
In the meantime, where there are differences between the MCLG and the
304(a) criteria for human health protection, EPA expects to continue to
recommend using as the water quality criterion the value that, in the
judgement of the State or Tribe, best accounts for the relevant routes
of exposure. Of course, EPA will also approve use of the more stringent
value.
Request for Comments on Human Health Criteria
EPA seeks public comment on the following questions:
1. Should the regulation require, or should guidance recommend,
higher intake assumptions for site-specific or regional situations when
subpopulations that are highly exposed have been identified? If so,
what should be the basis for such intake assumptions?
2. Should the regulation be modified to clarify (beyond the
guidance being proposed in 1998) the use of MCLs and MCLGs in State
water quality standards? [Note: Comments on the establishment of
similar assessment methodologies for deriving CWA criteria and MCLGs
should be made during the public comment period following the
anticipated 1998 Human Health Criteria Methodology proposal.]
15. Microbiological Criteria
Currently EPA has a criteria document titled ``Ambient Water
Quality Criteria for Bacteria--1986'' which provides information on
microbiological indicator organisms, sampling frequencies, and risk
based criteria guidance which States and Tribes can use in establishing
State or Tribal standards, especially for recreational waters. The
indicators used are the Enterococci for fresh and salt waters (33/100mL
and 35/100mL respectively) and E. Coli for fresh waters (126/100mL). It
is recommended that sampling be performed on a weekly basis and the
acceptability criteria are based on a running average level of the
indicators on a monthly basis. The EPA Office of Research has completed
a new Enterococci method (See ``Membrane Filter Test Method for
Enterococci in Water,'' EPA-821-R-97-004, May 1997). This indicator
method allows samples to be read in 24 hours rather than the 48 hours
of the old Enterococci method.
In 1997, EPA established the Beaches Environmental Assessment
Closure and Health Program (``BEACH'' Program) to protect the health of
beach goers through assistance to State, Tribal, and local health
officials in designing, developing and implementing beach monitoring
and advisory programs. The BEACH Program will also survey local beach
authorities about their programs and develop an Internet website to
provide the public with information on local beach water quality
conditions,
[[Page 36778]]
beach advisories and closures, and health risks associated with
swimming in contaminated water.
While the Enterococci and E. Coli indicators and criteria guidance
are satisfactory for determining risks from acute gastrointestinal
disease they are not necessarily acceptable for determining risks from
enteric viruses nor from pathogenic enteric protozoa such as Giardia
and Crypto Sporidium since these pathogens are much more resistant
environmentally and experience different treatment effectiveness. EPA
is currently evaluating how it may develop human health criteria for
protection from these organisms.
EPA may conduct additional research to develop indicator methods
for non-enteric pathogens that cause skin, respiratory, eye, ear, and
throat infections that are not detected by the current indicator
methods. EPA also intends to examine the phenomenon of regrowth of the
current indicators on soil and vegetation in tropical areas, and if
deemed necessary add indicator development studies to replace the
current indicators in tropical recreational areas. Further studies are
proposed to examine rapid chemical indicators of fecal pollution to see
if a tiered sampling protocol can be established for recreational water
monitoring. Also, EPA plans to examine the development of improved
monitoring strategies that States, Tribes and local authorities could
use to assess the true impact of pollution during wet weather events.
Finally, EPA will examine various computer models that could be used to
predict microbial pollution from storm water events in watersheds and
at recreational areas. These models would be validated by
microbiological monitoring.
Request for Public Comment on Microbiological Criteria
EPA seeks public comment on the following questions:
1. Where and how is it best to conduct future programs to determine
the safety of recreational waters?
2. What communication strategies would best inform the public about
pathogen exposures?
3. What guidance should EPA provide to States, Tribes, and local
governments on how to conduct beach monitoring activities?
16. Nutrient Criteria
In the National Water Quality Inventory 1994 Report to Congress,
nutrients (nitrogen and phosphorous) are cited as one of the leading
causes of water quality impairment in our Nation's rivers, lakes and
estuaries. While nutrients are essential to the health of aquatic
ecosystems, excessive nutrient loadings can result in the growth of
aquatic weeds and algae, leading to oxygen depletion, increased fish
and macro invertebrate mortality and other water quality impairments.
In December 1995, EPA held a National Nutrient Assessment Workshop with
the goal of developing a comprehensive nutrient strategy which would
provide tools that can be used in assessing and controlling nutrients
in all types of water bodies. Major conclusions from that workshop
were: (1) a single set of national nutrient criteria is not a realistic
goal, and (2) nutrient criteria need to be set on an ecoregional or
watershed basis. EPA has since been developing a national nutrient
strategy in order to communicate the specific approach and activities
necessary to meet the goals and major conclusions of the National
Nutrient Assessment Workshop.
On February 14, 1998, the ``Clean Water Action Plan'' was announced
by the Administrator of EPA and the Secretary of Agriculture. The
``Clean Water Action Plan'' is a blueprint for restoring and protecting
the Nation's precious water resources. As part of this Action Plan, EPA
intends to identify the major sources of nitrogen and phosphorous in
our waters and to identify actions to address these sources. In
particular, EPA intends to accelerate development of nutrient criteria
guidance for waters in every geographic region in the country, so that
EPA and the States and Tribes can begin implementing a criteria system
for nitrogen and phosphorous runoff for lakes, rivers, and estuaries by
the year 2000. EPA will assist States and Tribes in adopting numeric
water quality criteria for nitrogen and phosphorous, which EPA expects
will take the form either of State- or Tribe-derived criteria where
data is available, or criteria based on EPA default ranges applicable
to their ecoregion(s). Where a State or Tribe does not adopt
appropriate nutrient standards, EPA intends to begin the process of
promulgating nutrient standards. To support meeting these expectations,
EPA anticipates the following actions described below.
First, EPA intends to publish a National Nutrient Strategy which
will present currently available tools for assessing eutrophication,
identify important implementation issues related to controlling
eutrophication, and provide the Agency's plan for developing water
body-type guidance on nutrient over enrichment.
This national strategy will also present EPA's expectations for
action on the part of States and Tribes, namely, development of numeric
nutrient criteria and standards on a regional/watershed basis. Second,
by the end of the year 2000, EPA expects to publish the water body-type
guidance documents which would serve as ``user manuals'' for assessing
and controlling nutrient over enrichment for specific water body types:
lakes and reservoirs, rivers and streams, and estuarine and coastal
waters. These documents will include techniques for assessing the
trophic state of a water body and a methodology for developing region-
specific nutrient criteria. In each document, EPA intends to provide
regional nutrient ranges for phosphorus and nitrogen (and other
parameters), which EPA would expect States and Tribes to use in setting
nutrient criteria in the absence of any criterion that has been
developed site-specifically. EPA intends to use existing State and
Tribal projects and data, supplemented with new regional case studies
and demonstration projects that are being conducted to collect
information in data-limited areas of the country. An important
component in developing default nutrient values is determining the
appropriate scale of application (e.g., watershed, ecoregion, Northern
lakes/Southern lakes, etc.). Finally, in order to promote the use of
the water body-specific guidance, and ensure the development of
nutrient criteria on a watershed or ecoregional basis nationwide, EPA
will undertake several activities, including: (1) training in EPA
regions and States, and Tribes, through the use of Regional Technical
Assistance Centers; (2) appointing EPA Regional Nutrient Coordinators
who will oversee the development and implementation of nutrient
criteria and standards in each of the EPA Regions; and (3) offering
assistance grants which will provide financial support to States and
Tribes in their efforts to assemble existing data, including nutrient
endpoint data, and to establish nutrient criteria either by watershed
or ecoregion, where sufficient data are available.
Request for Comments on Nutrient Criteria
EPA requests comment on the following questions:
1. Should the regulation specifically require States and Tribes to
adopt and implement numeric nutrient criteria?
2. What capabilities do States and Tribes have right now for
developing and implementing water quality criteria for nutrients?
[[Page 36779]]
3. What are the institutional impediments to collecting nutrient
data and developing nutrient standards, for example, staff numbers and
expertise and financial resources?
4. Which States or Tribes are using an ecoregion or watershed
approach to develop numeric nutrient standards (EPA is aware of some
States doing this)? For those States and Tribes that do not, on what
scale do their nutrient standards apply--statewide or by water body
type?
D. Antidegradation
1. Background
The Federal antidegradation policy has its roots in the Water
Quality Act of 1965 (Pub. L. 89-234), which stated in its declaration
of policy, ``The purpose of this Act is to enhance the quality and
value of our water resources and to establish national policy for the
prevention, control, and abatement of water pollution.'' Policy
guidelines established by the Department of the Interior in 1966 for
use in the approval of States' water quality standards contained
additional direction on antidegradation, stating that ``In no case will
standards providing for less than existing quality be acceptable'' and
``The water quality standards proposed by a state should provide for: .
. . The maintenance and protection of quality and use or uses of waters
now of a high quality or of a quality suitable for present and
potential future uses.'' Secretary of the Interior Udall further
defined the Federal policy on antidegradation in 1968, when he said
that each State was to include a statement similar to the following in
their water quality standards:
Waters whose existing quality is better than the established
standards as of the date on which such standards become effective
will be maintained at their existing high quality. These and other
waters of a State will not be lowered in water quality unless and
until it has been affirmatively demonstrated to the State water
pollution control agency and the Department of the Interior that
such change is justifiable as a result of necessary economic or
social development and will not interfere with or become injurious
to any assigned uses made of, or presently possible in, such waters.
This will require that any industrial, public or private project or
development which would constitute a new source of pollution or an
increased source of pollution to high quality waters will be
required, as part of the initial project design, to provide the
highest and best degree of waste treatment available under existing
technology, and, since these are also Federal standards, these waste
treatment requirements will be developed cooperatively.
The Federal Water Pollution Control Act Amendments of 1972 (Pub. L.
92-500) continued to emphasize the prevention of pollution and, in
1973, EPA developed guidance for State water quality standards under
the Amendments that essentially repeated the 1968 statements of
Secretary Udall.
In 1975, EPA promulgated regulations at 40 CFR 130.17(e) that
required the States to develop an antidegradation policy and
implementation procedures. The 1975 rule contained provisions that are
very similar to those in 40 CFR 131.12, and provided protection for
existing uses, high quality waters, high quality waters that
constituted an outstanding National resource, and waters impaired by
thermal discharges. EPA issued final rules on November 8, 1983 (48 FR
51400) that retained, with certain changes, the 1975 antidegradation
policy and incorporated it into the regulations at 40 CFR 131.12. The
changes to the 1975 antidegradation policy are discussed in the
preamble to the 1983 rulemaking (48 FR 51402-51403), but they were
generally intended to clarify the policy with no change in coverage or
effect. An exception to this was the change in the provisions
applicable to outstanding National resource waters, which eliminated
the strict ``no degradation'' requirement in favor of a limited
exception for activities that result in temporary and short-term
lowering of water quality. The 1983 regulation (40 CFR 131.12(a))
provides that a State or Tribe is to identify its method for
implementing the antidegradation policy, i.e., decision measures for
assessing activities that may impact the integrity of a water body.
The 1987 Water Quality Act Amendments to the Clean Water Act (CWA)
explicitly incorporated reference to antidegradation policies in
section 303(d)(4)(B), which requires that such antidegradation
requirements be satisfied prior to modifying certain NPDES permits to
include less stringent effluent limitations (this concept is referred
to as antibacksliding).
On March 23, 1995, EPA published the final Water Quality Guidance
for the Great Lakes System (the Great Lakes Guidance). The Great Lakes
Guidance includes an antidegradation component that is intended to work
in conjunction with the other components of the Great Lakes Guidance to
address the most pressing threats to water quality in the Great Lakes.
In order to achieve this end, the focus of the antidegradation
component is on decisions pertaining to new or increased loadings of
specified bioaccumulative chemicals of concern within the Great Lakes
basin. For other types of pollutants, States and Tribes are required to
comply with the existing regulations at 40 CFR 131.12.
In the course of establishing a framework for making decisions
regarding increased loadings of bioaccumulative chemicals of concern,
the Great Lakes Guidance touches on a number of issues. The Great Lakes
Guidance provides a procedure for identifying high quality waters on a
pollutant-by-pollutant basis. The Great Lakes Guidance also defines how
a significant lowering of water quality will be identified for purposes
of determining whether or not an antidegradation review is required.
Finally, the Great Lakes Guidance includes implementation procedures
that describe how an antidegradation review should be conducted. In all
cases, the antidegradation components of the Great Lakes Guidance are
tailored to the control of bioaccumulative chemicals of concern; other
solutions may be necessitated by environmental threats faced elsewhere
in the Nation.
EPA's current thinking is that on a national scale, antidegradation
is not being used as effectively as it could be and that a structured
national debate on antidegradation is key to improvement. The debate
needs to identify deficiencies in antidegradation policy and
implementation provisions and begin the process of strengthening
antidegradation as a meaningful mechanism to attain and maintain water
quality standards. EPA invites comments and suggestions on the three-
tiered approach currently in use and described below, as well as
possible other approaches to more effectively accomplish the intent of
the antidegradation requirements. As part of the ``Clean Water Action
Plan'' announced on February 14, 1998 by the Administrator of EPA and
the Secretary of Agriculture, EPA plans to develop additional guidance
on Antidegradation. The discussion below articulates current EPA
thinking in several areas of antidegradation. Elements of this current
EPA thinking will likely be incorporated into the Antidegradation
guidance EPA develops under the ``Clean Water Action Plan.''
2. General Description of Antidegradation
An antidegradation policy performs an essential function as part of
the of States' and Tribes' water quality standards. Designated uses
establish the water quality goals for the water body, water quality
criteria define the minimum conditions necessary to achieve the goals
and an antidegradation policy specifies the framework to be used in
making
[[Page 36780]]
decisions regarding changes in water quality. The intent of an
antidegradation policy is to ensure that in all cases, at a minimum,
water quality necessary to support existing uses is maintained (tier
1), that where water quality is better than the minimum level necessary
to support protection and propagation of fish, shellfish and wildlife,
and recreation in and on the water (``fishable/swimmable''), that water
quality is also maintained and protected unless, through a public
process, some lowering of water quality is deemed to be necessary to
allow important economic or social development to occur (tier 2), and
to identify water bodies of exceptional recreational or ecological
significance and maintain and protect water quality in such water
bodies (tier 3). Antidegradation plays a critical role in allowing
States and Tribes to maintain and protect the finite public resource of
clean water and ensure that decisions to allow reductions in water
quality are made in a public manner and serve the public good.
The watershed approach may be a powerful tool to achieving
antidegradation goals (i.e., maintaining the chemical, physical, and
biological integrity of the Nation's waters). Many and varied uses are
made of the Nation's waters and in some cases, these uses conflict. The
ability of particular waters to accommodate all uses is limited. High
quality surface waters are an important and finite resource whose
availability affects the health, welfare, and economic well-being of
all the citizens of the United States. When operating properly, the
antidegradation policies of States and Tribes ensure that water quality
is conserved where possible and lowered only when necessary, and that
those affected by the lowering of water quality have a say in the final
decision. As a result, antidegradation policies are well-suited to
assist States, Tribes and local communities in establishing and
achieving watershed goals. Sensitive or highly valued water bodies can
be identified and protected from degradation through outstanding
national resource water (ONRW) or related designations. In other water
bodies, where water quality is better than the minimum necessary to
support fish and aquatic life and recreation, water quality should be
maintained unless there is a demonstrated need to lower water quality.
Consistent with the watershed approach and community-based
environmental management, States' and Tribes' antidegradation policies
and procedures can be a basis for a systematic and accessible planning
process that protects against development having negative impacts on
water quality. Additional authorities exist at the local level beyond
State, Tribal and federal authorities which may allow additional
protections to be put in place in accordance with the watershed
management plan.
The water quality standards regulation requires each State and
authorized Tribe to adopt, as part of its water quality standards, an
antidegradation policy consistent with 40 CFR 131.12 and identify
implementation methods for such a policy. This antidegradation policy
provides a multi-level approach for the protection of water quality and
applies to both point and non-point source activities. The level of
protection that is provided to a specific segment depends upon a number
of factors (e.g., a key determinant is whether existing water quality
is found to exceed levels necessary to support ``fishable/swimmable''
uses). Antidegradation requirements are typically triggered when an
activity is proposed that may have some effect on existing water
quality. Such activities are reviewed to determine, based on the level
of antidegradation protection afforded to the affected water body
segment, whether the proposed activity can be authorized.
``Antidegradation reviews'' under all three tiers of antidegradation
should be documented and subjected to public review and comment (e.g.,
as part of the public review of the water quality certification, NPDES
permit, or other regulatory action).
Identifying the universe of activities that trigger antidegradation
requirements is a fundamental and often controversial issue because of
the number and variety of activities that can affect water quality.
Clearly, a wide range of activities that affect water quality may be
subject to antidegradation requirements, and States and Tribes have
considerable flexibility in applying antidegradation policies.
The federal antidegradation requirements do not create, nor were
they intended to create, State or Tribal regulatory authority over
otherwise unregulated activities. It is the position of EPA that, at a
minimum, States and authorized Tribes must apply antidegradation
requirements to activities that are ``regulated'' under State, Tribal,
or federal law (i.e., any activity that requires a permit or a water
quality certification pursuant to State, Tribal or federal law, such as
CWA Sec. 402 NPDES permits or CWA Sec. 404 dredge and fill permits, any
activity requiring a CWA Sec. 401 certification, any activity subject
to State or Tribal nonpoint source control requirements or regulations,
and any activity which is otherwise subject to State or Tribal
regulations that specify that water quality standards are applicable).
Where a State or Tribe wishes to require antidegradation reviews for
activities that are not currently ``regulated'' under this definition,
EPA recommends that a complete discussion of the activities requiring
an antidegradation review be included in the State or Tribal water
quality standards or other State or Tribal regulation. Although States
and authorized Tribes have discretion to apply antidegradation
requirements more broadly than minimally required, application of
antidegradation requirements to activities that are otherwise
unregulated under State, Tribal, and federal water law is not required
by the federal water quality standards regulation.
EPA's current thinking is that antidegradation principles can and
should be considered in connection with a number of activities even
where application of the antidegradation review requirements is not
explicitly required by the regulation. EPA is interested in identifying
ways to better implement antidegradation, especially for activities
such as urban and agricultural run-off. As part of general planning for
development that is likely to affect surface water quality, it makes
sense to consider existing ambient water quality and evaluate available
means to protect that water quality. Thus, although a State or Tribe
may not require a formal antidegradation review for a particular
activity (e.g., an unregulated nonpoint source), there may still be
value in applying the antidegradation principles in an analysis of
potential environmental impacts.
In sum, EPA's current thinking is that the antidegradation policy
is significantly underused as a tool to attain and maintain water
quality and plan for and channel important economic and social
development that can impact water quality. EPA believes this is
especially true for nonpoint source run-off. This ANPRM provides an
opportunity to identify and evaluate options for clarifying and
strengthening antidegradation policy and its implementation.
States and authorized Tribes often submit implementation procedures
to EPA for review as part of the water quality standards triennial
review required by section 303(c) of the Act. This enables EPA to
determine if the implementation procedures fulfill the requirements of
the antidegradation
[[Page 36781]]
policy. The antidegradation policy itself is expressly required by 40
CFR 131.20(c) to be submitted to EPA for review. EPA's longstanding
policy is that the implementation procedure should also be submitted to
EPA for review. Often, however, implementation procedures are not
submitted to EPA. EPA's current thinking is that an important change to
the regulation would be to clarify under 40 CFR section 131.20(c) that
State and Tribal antidegradation implementation procedures (in addition
to the policy) must be included in the submittal of a State's or
Tribe's water quality standards. Such a change could establish the
foundation for additional substantive changes to the regulation
concerning national norms for antidegradation implementation
procedures.
A State's or Tribe's implementation method is on occasion so
constructed as to essentially set aside the intent of the
antidegradation policy. EPA has disapproved this aspect of State
standards where the implementation procedure is inconsistent with the
policy. Revising the regulation to specify requirements addressing the
content of such implementation procedures (e.g., a core set of issues
that must be resolved), and clarifying that implementation procedures
must be included in the submittal package, may help to clarify EPA's
role in determining whether State or Tribal antidegradation
implementation procedures adequately uphold and implement the State's
or Tribe's antidegradation policy. In addition, specifying in the
regulation the basic elements of an implementation procedure could
serve to better establish national norms for State and tribal
antidegradation procedures. EPA is considering whether it would assist
States and Tribes if the regulation were amended to identify the basic
elements that must be included in an antidegradation implementation
method.
Guidance on developing antidegradation implementation methods is
provided through EPA's Regional Offices. EPA has not issued national
guidance on these implementation methods and is interested in comments
on whether national guidance on antidegradation implementation methods
is needed, and whether elements of such guidance should be referenced
or included in the Regulation.
Request for Comments on General Antidegradation Policy
EPA requests comment on the following questions:
1. What changes or clarifications could be made to the current
tiered approach to protecting waters under antidegradation that would
streamline and enhance antidegradation implementation?
2. Should the regulation be amended to identify the basic elements
that must be included in an antidegradation implementation method and
would such changes assist States and Tribes in understanding the
requirements and in utilizing the flexibility available?
3. Is national guidance on antidegradation implementation methods
needed and should elements of such guidance be referenced or included
in the Regulation?
3. 40 CFR 131.12 (a)(1) ``tier 1''
Section 131.12 (a)(1) of the antidegradation policy contained in
the water quality standards regulation requires that existing uses and
the water quality necessary to protect them be maintained and
protected. This provision, in effect, establishes the floor of water
quality in the U.S. It also protects the environment where the existing
use of a water body happens to be better than the use designated by the
State or Tribe. An existing use as defined in 40 CFR 131.3 can be
established by demonstrating that a use has actually occurred since
November 28, 1975, or that the water quality is suitable to allow such
uses to occur, whether or not such uses are designated uses for the
water body in question. All waters of the U.S. are subject to tier 1
protection. In general, waters that are subject to only tier 1
antidegradation policies are those water bodies that do not exceed the
CWA Section 101(a)(2) goals, or do not have assimilative capacity to
receive additional quantities of a pollutant(s) without jeopardizing
the existing use. Existing uses and additional issues related to
defining them and their relationship to designated uses are further
discussed in section III(B)(3) of this document.
Antidegradation policies are generally implemented for tier 1 by a
review procedure that evaluates any discharge to determine whether it
would impair an existing use. Prior to authorizing any proposed
activity, a State or authorized Tribe shall ensure that water quality
sufficient to protect existing uses fully will be achieved. In addition
to ensuring that existing uses will be protected, the State or Tribe
should ensure that all existing uses are designated in accordance with
40 CFR 131.10(i).
a. Tier 1 Implementation. In order to implement tier 1, a State or
Tribe must define what is meant by the term ``existing in-stream water
use'' (40 CFR 131.12(a)(1)) and must also be able to identify the level
of water quality that is required to permit an existing use to continue
to occur. Section 131.3 defines existing uses as, ``those uses actually
attained in the water body on or after November 28, 1975 * * *''
Traditionally, when establishing designated uses, States and Tribes
tend to define uses in terms of broad classes, such as warm water
fishery or secondary contact recreation. Inherent in each of the broad
use categories are specific uses that may be affected by a change in
water quality. For example, a warm water fishery designated use may
include the existing use of large mouth bass fishery. Many people would
be upset if the warm water fishery designated use was protected in such
a way as to allow a decline in the bass population. The central
question faced by States and Tribes in determining whether or not a
proposed action will impact existing uses is whether each specific use
within a use class must be maintained (each individual type of
species), or whether only the use class itself must be maintained
(allow changes in species composition, but maintain a fishery). State
and Tribal interpretations of this requirement vary considerably and
are often tied to the degree of precision the State or Tribe achieves
in defining designated uses.
Many States and some Tribes have addressed these questions by using
the same degree of precision for both designated and existing uses.
EPA's current thinking is that this is an acceptable approach as long
as the State's or Tribe's designated uses and criteria applicable to
those uses are adequate to ensure that existing uses are maintained
under the federal antidegradation provisions. It would not be
acceptable, for example, for a state to allow the loss of an existing
natural cold water community in favor of a warm water community because
both satisfy the general use designation of ``aquatic life.'' Nor would
it be acceptable to allow shifts from existing pollution intolerant
communities to communities that tolerate degraded conditions. The
advantage of this approach is that the same criteria used to protect
the designated use can be assumed to also protect the existing use.
Under this approach, however, the protection afforded to existing uses
is limited by the degree of refinement associated with the designated
uses. States and Tribes that have more specific designated uses (i.e.,
including a number of use sub-categories) can potentially provide more
protection by addressing more subtle changes to the existing use.
States and
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Tribes with less specific designated uses would have less precision
associated with their existing use protection scheme.
An important tier 1 implementation issue concerns how a State or
Tribe will prevent negative or harmful impacts to existing uses when
water quality criteria that have been established to protect the
designated uses are not adequate to protect the existing uses. For
example, a regulated discharge of uncontaminated sediment may result in
significant negative or harmful impacts to aquatic life habitat and
loss of aquatic life use. In such cases, where clean sediment or
siltation criteria have not been developed for the site, and where the
State or Tribe has not established clear procedures to implement
narrative criteria governing sedimentation, it may be difficult to
prohibit such loss of use, particularly where a State or Tribe has not
adopted biological criteria.
A second example arises where a proposed activity will result in
the discharge of a substance for which numeric criteria have not been
adopted by the State or Tribe, but sufficient data to derive criteria
or a numeric translation of the narrative criteria are available. Where
a range of numeric criteria can potentially be justified for the
particular substance to protect the designated and/or existing use, it
may be difficult or contentious for the State or Tribe to derive
effluent limits protective of the existing use.
A third example arises where a proposed hydrologic modification
will result in diminished flow in a water body and create the potential
for loss of existing aquatic life use either through increased
temperatures or turbidity, or loss of habitat. State and Tribal water
quality criteria generally do not describe minimum acceptable flows and
may not, by themselves, adequately protect against such loss of use. In
P.U.D. No. 1 of Jefferson County and City of Tacoma v. Washington
Department of Ecology, (114 S.Ct 1900 (1994)), the Supreme Court ruled
that State certifications under section 401 of the CWA may include
conditions to ensure compliance not only with a State's water quality
criteria, but also with a State's designated uses or antidegradation
policy. The Court concluded that a State could require, in this case, a
dam to be designed and operated in such a way as to maintain stream
flows necessary to protect the designated use of a stream. While this
specific case had to do with a dam and stream flows necessary to
protect a use, it should be noted that the opinion applies more broadly
than to just flow and that in addition to maintenance of in-stream
flows to protect water quality standards, States may also apply any
other parameter that may not be specifically identified in the State's
standards. EPA notes that where such implementation methods are spelled
out, as a practical matter, they may be more easily implemented. (See
related discussion in Section III.B. on uses). EPA believes that tier 1
methods or policies for addressing situations such as those described
above may need to be included in an antidegradation implementation
procedure.
Request for Comments on Antidegradation Tier 1
EPA specifically requests public comment on the following
questions:
1. Do State and Tribal programs under the existing regulation do an
adequate job of protecting existing in-stream uses?
2. Is a more detailed definition of ``existing in-stream water
uses'' needed in the regulation? Should it be the same as ``existing
uses?'
3. Should the regulation define what constitutes loss of an
existing in-stream water use?
4. Should a clear approach to maintaining and protecting existing
uses that may not be adequately protected by strict application of
water quality criteria be a required element of an antidegradation
implementation procedure?
5. Should the regulation specify under antidegradation that
protection of both existing and designated uses is required?
4. 40 CFR 131.12 (a)(2) ``tier 2''
``Tier 2'' (Sec. 131.12(a)(2)) antidegradation policies are
intended to protect the waters in which water quality is better than
necessary to support propagation of fish, shellfish and wildlife, and
recreation in and on the water body. These are called high quality
waters. For such high quality waters, existing water quality must be
maintained and protected unless it is demonstrated that a lowering of
water quality is necessary to accommodate important economic or social
development. The protection of high quality waters envisioned by the
regulation encourages a systematic, public decision making process for
determining whether or not to allow limited deterioration of water
quality in high quality waters.
a. Identification of ``High Quality'' Waters. Identifying waters
that are ``high quality'' and subject to tier 2 protection is an
important antidegradation issue. The water quality standards regulation
requires application of tier 2 requirements ``where the quality of the
waters exceed levels necessary to support propagation of fish,
shellfish, and wildlife and recreation in and on the water.'' However,
the regulation does not include specific guidelines for identifying
high quality waters. Various EPA guidance documents, including those
issued by EPA's Regional offices, make a variety of suggestions
concerning approaches to defining tier 2 waters. Not surprisingly,
States and Tribes have developed various ways to identify tier 2
waters.
Existing approaches for identifying high quality waters fall into
two basic categories: (1) pollutant-by-pollutant approaches, and (2)
water body-by-water body approaches. States and Tribes following the
first approach determine whether water quality is better than
applicable criteria for specific pollutants that would be affected by
the proposed activity. Thus, available assimilative capacity for any
given pollutant is always subject to tier 2 protection, regardless of
whether the criteria for other pollutants are satisfied. Such
determinations are made at the time of the antidegradation review
(i.e., as activities that may degrade water quality are proposed).
States and Tribes following the second approach weigh a variety of
factors to judge a water body segment's overall quality. Such
determinations may be made prior to the antidegradation review (i.e.,
the State or Tribe may assign ``high quality'' designations in the
State or Tribal standards), or during the course of the antidegradation
review. Under this water body-by-water body approach, sometimes
referred to as the ``designational'' approach, assimilative capacity
for a given pollutant may not be subject to tier 2 protection if,
overall, the segment is not deemed ``high quality.''
There are advantages and disadvantages to each approach. EPA's
current thinking is that neither approach is clearly superior and that
either, when properly implemented, is acceptable. EPA has approved both
approaches in State standards. Some States and Tribes have found the
pollutant-by-pollutant approach to be easier to implement because the
need for an overall assessment considering various factors is avoided.
Also, decisions are driven strictly by water column data (i.e., rather
than judgments concerning a segment's overall value or quality) and
thus may be less susceptible to challenge. The pollutant-by-pollutant
approach may result in more waters receiving some degree of tier 2
protection because it would cover
[[Page 36783]]
waters that are clearly not attaining goal uses (i.e., waters which are
not supporting ``fishable/swimmable'' goal uses but that possess
assimilative capacity for one or more pollutant).
The water body-by-water body approach, on the other hand, allows
for a weighted assessment of chemical, physical, biological, and other
information (e.g., unique ecological or scenic attributes). In this
regard, the water body-by-water body approach may be better suited to
EPA's stated vision for the water quality standards program: refined
designated uses with tailored criteria, complete information on uses
and use attainability, and clear national norms. The water body-by-
water body approach preserves water quality even if criteria for
certain pollutants are not attained or if criteria for certain uses may
be limited, such as fish consumption. This approach also allows for the
high quality water decision to be made in advance of the
antidegradation review (and included in the water quality standards for
the segment), which may facilitate implementation. A water body-by-
water body approach also allows States and Tribes to focus limited
resources on protecting higher-value State or Tribal waters. The water
body-by-water body approach can also distinguish between high quality
waters and high water quality and preserve high quality waters on the
basis of physical and biological attributes, rather than high water
quality attributes alone. However, the flexibility of the water body-
by-water body approach is also its principal disadvantage where a State
or Tribe does not develop inclusive qualification criteria. For
example, where a State's or Tribe's implementation guidelines define a
narrow universe of waters, many deserving high quality waters may not
receive tier 2 protection. Thus water quality may actually decrease in
the waters not classified for tier 2 protection without a public review
of the development decision. Also, a potential problem can arise if the
process of identifying high quality waters becomes so complicated,
resource-intensive, and data-intensive that the primary purpose of tier
2 (i.e., seeking to maintain and protect existing quality by
identifying whether there are reasonable less-degrading or non-
degrading alternatives) is not adequately accomplished. In other words,
the limited resources available for water quality protection could be
spent on the identification process at the expense of analysis of the
necessity for degradation.
b. Tier 2 Implementation. The current regulation provides a great
deal of flexibility to States and Tribes in implementing tier 2
requirements. Some States and Tribes devote little effort to
implementing their tier 2 requirements, some States and Tribes apply
tier 2 requirements in an inconsistent or infrequent manner, and other
States and Tribes have active programs that routinely and consistently
implement tier 2. In general, those States and Tribes that actively
implement their tier 2 requirements do so by conducting an
antidegradation review to determine whether proposed activities that
might affect water quality may be authorized. EPA's current sense is
that the antidegradation policy, in reality, has little effect on
decisions related to surface water quality unless the State or Tribe
adopts an implementation procedure and uses it. EPA currently reviews
all State and Tribal water quality standards at the time of adoption/
revision to ensure they establish a clear approach to implementation. A
brief discussion of a number of the major implementation issues is
presented below.
i. Triggers for tier 2 Review. Although not discussed in 40 CFR
131.12 of the water quality standards regulation, State and on occasion
Tribal tier 2 implementation procedures often include guidelines which
are used to determine when the water quality degradation that will
result from a proposed activity is significant enough to warrant
further antidegradation review. Where the degradation is not
significant, the antidegradation review is typically terminated for
that proposed activity. The significance evaluation is usually
conducted on a pollutant-by-pollutant basis, even where a water body-
by-water body approach is used to identify high quality waters, and
significant degradation for any one pollutant triggers further review
for that pollutant.
Applying antidegradation requirements only to activities that will
result in significant degradation is a useful approach that allows
States and Tribes to focus limited resources where they may result in
the greatest environmental protection. However, there is a great deal
of variation in how States and Tribes define significant degradation.
Significance tests range from simple to complex, involve qualitative or
quantitative measures or both, and may vary depending upon the type of
pollutant (e.g., the approach may be different for highly toxic or
bioaccumulative pollutants). In some cases, States have also created
categorical exemptions from tier 2 review (e.g., they have exempted
entire categories of activities from antidegradation reviews based on a
general finding that such activities do not result in significant
degradation). States or Tribes that define a high threshold of
significance may be unduly restricting the number of proposed
activities that are subject to a full antidegradation review. Further
the approach currently used by some States may not adequately prevent
cumulative water quality degradation on a watershed scale. The current
regulation does not specify a significance threshold below which an
antidegradation review would not be required. EPA's current thinking is
that a clear national norm regarding this ``significance test'' is
necessary and should be developed and established in either the
regulation or national guidance.
A related issue concerns whether tier 2 should be applied to
pollutants where numeric criteria have not been adopted. For example,
where there is a proposed discharge of a pollutant to a ``high
quality'' segment, and the background concentration of the pollutant is
at or near zero in the water body, should significant degradation be
evaluated and should it be evaluated any differently where numeric
criteria for the pollutant have not been adopted? For example, where a
State or Tribe lacks numeric criteria for nutrients such as nitrogen
and phosphorus (a common occurrence), increased discharges of these
nutrients can be expected to result in changes in plant life or species
diversity. If the State or Tribe relies entirely on a pollutant
loadings comparison to numeric criteria for the tier 2 evaluation, new
loadings of nutrients may not even be evaluated under tier 2.
EPA's sense is that, in practice, the current tier 2 requirements
tend to be used to protect high quality waters only where such high
quality supports fishing and swimming uses. However, limiting tier 2
protection to assimilative capacity associated with only fishing and
swimming uses means that the protection afforded by tier 2 can end up
being narrower than intended. For example, where a water has unique
ecological significance (e.g., acid bog or thermal spring) not captured
by ``fishable/swimmable,'' the State or Tribe may not believe it is
appropriate to designate the water as high quality under tier 2. In
this case, the unique ecological characteristic would warrant
protection as an existing use. The State or Tribe also has the option
of designating the water ONRW, yet, as discussed elsewhere in this
section, EPA believes that many States and Tribes are not inclined to
designate waters ONRW. The result in this example is that a water with
unique
[[Page 36784]]
ecological significance that may warrant a relatively high level of
protection, falls through the crack between tiers 1 and 2 where the
State or Tribe interprets the level of protection afforded by those
tiers too narrowly.
ii. ``Necessary'' Lowering of Water Quality. The water quality
standards regulation requires that the water quality of high quality
waters not be lowered unless the State or Tribe determines that such
degradation is necessary to accommodate important social and economic
development. Given the variety of available engineering approaches to
pollution control and the emerging importance of pollution prevention,
the finding of necessity is among the most important and useful aspects
of an antidegradation program and potentially an extremely useful tool
in the context of watershed planning. An approach that has been
recommended by EPA is to require the proponent of the proposed activity
to develop an analysis of pollution control/pollution prevention
alternatives. In conducting its antidegradation review, the State or
Tribe then ensures that all feasible alternatives to allowing the
degradation have been adequately evaluated, and that the least
degrading reasonable alternative is implemented. Also, note that where
less-degrading alternatives are more costly than the pollution controls
associated with the proposal, the State or Tribe should determine
whether the costs of the less-degrading alternative are reasonable. EPA
believes that such an alternatives analysis approach can be an
effective tool for maintaining and protecting existing assimilative
capacity. EPA's current thinking is that specifying what would
constitute an acceptable alternatives analysis in the regulation, could
result in the addition of substance and rigor to the ``tier 2''
antidegradation reviews conducted by States and Tribes.
iii. Identification of ``Important'' Social or Economic Activities.
Another task that must be completed as part of an antidegradation
review is to evaluate whether a proposed activity that will result in
degradation is necessary to accommodate important social or economic
development in the area in which the waters are located. (40 CFR
131.12(a)(2)) The significance of determining if an activity will
provide for important social or economic benefit is that, absent
important social or economic benefit, degradation under tier 2 must not
be allowed. Factors that may be addressed in such an evaluation
include: (a) employment (i.e., increasing, maintaining, or avoiding a
reduction in employment), (b) increased production, (c) improved
community tax base, (d) housing, and (e) correction of an environmental
or public health problem. Some States or Tribes have addressed this
issue by requiring the applicant to bear the burden of demonstrating
the social and economic importance of the proposed activity. However,
approaches for evaluating social and economic importance vary widely.
EPA published Interim Economic Guidance for Water Quality Standards:
Workbook, Appendix M to the ``Water quality Standards Handbook--Second
Edition'' in March 1995 (EPA-823-B-95-002, March 1995). This guidance
specifically addresses the determination of social and economic
importance in the context of a tier 2 antidegradation review and should
be useful to States and Tribes in determining the relative economic
consequences of various development proposals and their relationship to
water quality standards. EPA's current thinking is that determining the
social and economic importance of a proposed activity is an important
public question best addressed by State, Tribal or local interests,
perhaps as part of the development of a basin plan.
iv. Tier 2 and Identification of Waters under CWA Section 303(d).
Section 303(d) of the Clean Water Act and EPA regulations require
States to develop lists of waters that do not meet State water quality
standards, even after point sources of pollution install the minimum
required levels of pollution control technology. Section 303(d) lists
must be submitted to EPA every two years. The waters on the lists are
called water quality-limited waters and are defined in EPA regulations
as waters ``where it is known that water quality does not meet
applicable water quality standards, and/or is not expected to meet
applicable water quality standards, even after the application of the
technology-based effluent limitations required by section 301(b) and
306 of the [Clean Water] Act.'' 40 CFR 130.2(j). States are then
required to develop total maximum daily loads (TMDLs) for water
quality-limited waters.
EPA's current policy is that States include waters on section
303(d) lists if applicable water quality standards are not met or are
not expected to be met by the next list submission deadline, i.e.,
within two years (see memorandum from Robert Wayland, Director Office
of Wetlands, Oceans and Watersheds, to Water Management Division
Directors, Regions I-X, Directors Great Water Body Programs and Water
Quality Branch Chiefs, Regions I-X, Subject: National Clarifying
Guidance for 1998 State and Territory Section 303(d) Listing Decisions,
August 27, 1997). In determining whether to list waters, States should
consider all aspects of applicable water quality standards, including
narrative and numeric criteria, designated uses, and antidegradation
policies.
EPA is currently discussing with stakeholders possible changes and
clarifications to the water body listing regulations and guidance under
section 303(d) of the Act. Changes and/or clarifications could include
a statement in the regulation, or a clarification, that identifies
existing tier 2 antidegradation analyses and decisions as ``existing
and readily available water quality-related data and information'' that
must be considered under 40 CFR 130.7(b)(5) when deciding whether to
place a water body on a section 303(d) list. Information from existing
antidegradation tier 2 reviews on assimilative capacity for particular
water bodies could be used to determine whether a water body is likely
to not meet water quality standards in the near future and thus
required to be included on the section 303(d) list. In addition, EPA
could amend the existing antidegradation regulations to direct States
and Tribes to consider the 303(d) listing status of a water body, and
the information supporting that status, when determining whether a
proposed activity that is expected to degrade water quality in that
water body can be authorized under tier 2 of the State's or Tribe's
antidegradation provisions.
v. Achieving all cost-effective and reasonable best management
practices for nonpoint sources. This implementation issue arises from
one sentence that is included in the federal antidegradation policy at
40 CFR 131.12(a)(2):
Further, the State shall assure that there shall be achieved the
highest statutory and regulatory requirements for all new and
existing point sources and all cost-effective and reasonable best
management practices for nonpoint source control.
This sentence has been somewhat controversial over the years
because it could be interpreted to require a State or Tribe to include,
in its water quality standards, a provision requiring adoption of
authority for, as well as achievement of, best management practices
(BMPs) for nonpoint sources prior to allowing degradation of high
quality waters. EPA has interpreted 131.12(a)(2) as not requiring a
State or Tribe to establish BMP requirements for nonpoint sources where
such BMP requirements do not exist. As EPA clarified in a February 22,
1994 guidance memorandum, State and
[[Page 36785]]
Tribal antidegradation rules need only include provisions to assure
achievement of BMPs that are required under State or Tribal nonpoint
source control laws or regulations. (Memorandum from Tudor T. Davies,
Director EPA Office of Science and Technology to EPA Water Management
Division Directors, Regions I-X, Subject: Interpretation of Federal
Antidegradation Regulatory Requirement, February 22, 1994) Thus, States
and Tribes that have adopted nonpoint source controls must assure that
such controls are properly implemented before authorization is granted
to allow point source degradation of water quality.
EPA's current thinking is that the term ``all cost-effective and
reasonable best management practices for nonpoint source control'' in
40 CFR 131.12(a)(2) would be more effective if read more broadly. In
other words, the term could include nonpoint source best management
practices established through Federal, State, Tribal, and local
authorities and programs that address activities on the land or water
that create or exacerbate impacts to surface waters. This construction
is consistent with EPA's Total Maximum Daily Load (TMDL) program under
Section 303(d) of the Clean Water Act. There, EPA's current policy is
that in achieving pollutant load reductions from nonpoint sources, EPA
and States should work in partnership, using all available Federal,
State, and local authorities and programs. As EPA stated in an August
1997 TMDL guidance memorandum, States are expected to achieve nonpoint
source pollutant load reductions through such authorities and programs,
including non-regulatory, regulatory, or incentive-based programs. EPA
is considering applying the same test to Sec. 131.12(a)(2).
In addition, EPA's current thinking is that it may be time to begin
to more actively ensure implementation of this requirement: to
implement cost effective and reasonable best management practices for
nonpoint source control before allowing lowering of water quality in a
water body. One way to do this would be to specify that State and
Tribal antidegradation implementation procedures include a step under
which States and Tribes inventory their nonpoint source authorities and
programs, and, as part of each antidegradation review, include in the
record documentation on how those authorities and programs were applied
to activities in a watershed in which additional loadings subject to an
antidegradation review have been considered. Emphasizing this
requirement by specifying it as a required aspect of a State or Tribal
antidegradation implementation procedure, in EPA's view, would
facilitate use of antidegradation policy as a tool to ensure that
nonpoint sources are controlled where possible in accordance with water
quality standards, before any additional assimilative capacity in a
water body can be allocated to an activity. EPA is interested in
comment on this current thinking and specifically on whether it would
be helpful to revise the regulation to clarify the relationship between
nonpoint source controls and tier 2 antidegradation requirements.
In summary, numerous stakeholders have commented to EPA that
antidegradation reviews are conducted inconsistently across the country
and that EPA should attempt to improve the national consistency of such
reviews. EPA is interested in comment on the appropriate balance
between national consistency and State and Tribal flexibility in the
implementation of the tier 2 provision and on what changes may be
needed to the regulation or EPA policy or guidance to ensure that the
tier 2 provision is implemented in a nationally consistent manner that
is consistent with the intent of the antidegradation provision, and
whether a consistent approach should be the goal of States' and Tribes'
watershed programs.
Request for Comments on Antidegradation Tier 2
EPA requests comment on the following questions:
1. Does the existing requirement to apply tier 2 ``where the
quality of the waters exceed levels necessary to support propagation of
fish, shellfish, and wildlife and recreation in and on the water''
while at the same time ``protecting existing uses fully'' need to be
clarified with respect to which waters are afforded tier 2
antidegradation protection, and if so, should the Agency clarify the
requirement with additional guidance, or with revisions to the
regulation?
2. What factors should be considered in identifying ``high
quality'' waters? Should the decision be based strictly on chemical
water column quality (i.e., a pollutant-by-pollutant approach), or
should a segment's overall quality or other factors be considered
(i.e., a water body-by-water body approach)?
3. Given EPA's current thinking that both approaches may be
acceptable and neither is necessarily superior, are the two approaches
compatible and could they be implemented together?
4. Should application of tier 2 be clarified so that protection of
assimilative capacity associated with non-fishable/swimmable uses is
clearly required?
5. What methods are currently being used by States and Tribes to
define ``significant degradation''?
6. How should ``significant degradation'' be defined? Is there a
need for a nationally consistent approach? Should EPA issue additional
guidance, or revise the regulation to include, for purposes of
implementing tier 2 requirements, a definition of significant
degradation? Are categorical exemptions appropriate, and if so, under
what circumstances?
7. How should cumulative effects in a watershed be considered in
assessing the significance of the degradation that will occur as a
result of a proposed activity?
8. How should the ``necessity'' of degradation be determined? When
should the costs of less degrading alternatives be considered
reasonable?
9. How should significant degradation be evaluated for pollutants
where no numeric criterion has been adopted?
10. Is additional Agency guidance or regulatory requirements
necessary to help States and Tribes address social and economic
importance (e.g., additional methods or options beyond those discussed
in the March 1995 Interim Economic Guidance document)?
11. Should evaluating the importance of proposed discharges be
entirely a State or Tribal determination and not be a required element
for EPA review?
12. Would it be appropriate to revise the regulation to clarify the
relationship between nonpoint source controls and tier 2
antidegradation requirements?
13. Should EPA revise the regulation to expressly state that States
and Tribes are to consider the 303(d) listing status of a water body,
and the information supporting that status, when determining whether a
proposed activity that is expected to degrade water quality in that
water body can be authorized under tier 2 of the State's or Tribe's
antidegradation provisions?
14. Is greater consistency between individual State and Tribal
programs desirable and, if so, what changes may be needed to the
regulation or EPA guidance to ensure that the tier 2 provision is
implemented in a nationally consistent manner?
5. 40 CFR 131.12 (a)(3) ``Tier 3''
Tier 3 of the antidegradation policy is intended to identify and
protect waters of extraordinary ecological, recreational or other
significance. Tier 3 of the antidegradation policy incorporates the
[[Page 36786]]
concept of Outstanding National Resource Waters (ONRW). The rationale
for this provision is that some water bodies are of such high quality
or of such exceptional ecological significance that the commonly
applied designated uses such as warm water fishery and primary contact
recreation and criteria to protect those uses are not suitable or may
not provide adequate protection to maintain the high water quality or
ecological significance in a given water body.
ONRWs are intended to include the highest quality waters of the
United States. Additionally, the ONRW antidegradation classification
offers special protection for waters of ``exceptional ecological
significance,'' i.e., those water bodies which are important, unique,
or sensitive ecologically, but whose water quality, as measured by the
traditional characteristics such as dissolved oxygen or pH, may not be
particularly high, such as thermal springs. Waters of exceptional
ecological significance also include waters whose characteristics
cannot adequately be described by traditional parameters (such as
wetlands and estuaries).
Tier 3 of the antidegradation policy provides the highest level of
protection to water bodies by prohibiting the lowering of water
quality. The only exception to this prohibition as discussed in the
preamble to the water quality standards regulation is for activities
that result in short-term and temporary changes in the water quality of
the ONRW. EPA guidance has not defined temporary and short-term
specifically, but views these terms as limiting water quality
degradation for weeks or months, not years. The intent is to limit
degradation to the shortest possible time.
a. Designating ONRWs. The designation of water bodies as ONRWs has
been limited in its application. Overall, there are relatively few
water bodies designated as ONRWs in the United States, although some
States have designated a high percentage of State waters as ONRWs.
Several States have been reluctant to adopt ONRWs because of concerns
regarding the process for adopting ONRW classifications and the level
of protection afforded to a water once it is classified as an ONRW.
Regarding the process for adoption of ONRWs, the existing
regulation requires the State or Tribe to provide an ONRW level of
protection in their antidegradation policies, but there is no
requirement that any water body be so designated or any specificity as
to how that is to be done. One way to address this issue may be for EPA
to amend the regulation to require States and Tribes to establish a
nomination process with criteria guidelines in which the public could
petition the State or Tribe for designation of certain waters as ONRWs.
It would then be up to the State or Tribe to set criteria for the ONRW
selection process with the final decision made by the State or Tribe
after consideration of the public comment. EPA currently recommends
three categories of waters which could be eligible for ONRW
designation: waters of (1) National and State parks, (2) wildlife
refuges, and (3) exceptional recreational or ecological significance.
Regarding the level of protection that is afforded to a water body
once it is classified as an ONRW, a common concern is that classifying
a water as ONRW will result in a federal prohibition on any further
development of any kind in the watershed. As described above, the
federal antidegradation policy regarding ONRWs is that once classified
as an ONRW, the water quality of the ONRW must be maintained and
protected. One way, but perhaps not the only way, to ensure that the
water quality is maintained and protected would be to prohibit
activities that would generate additional pollutant loads and or water
quality impacts in the ONRW. This approach is commonly referred to as
``no new or increased discharge'' and was explained by EPA in its
promulgation of antidegradation provisions for the State of
Pennsylvania in 1996 (61 FR 64816, December 9, 1996). As discussed in
the Pennsylvania rule, the federal policy requiring the water quality
to be maintained and protected is subject to some interpretation by
States and Tribes.
EPA believes there is considerable uncertainty from jurisdiction to
jurisdiction concerning the impact of the ONRW classification on the
local community or the State or Tribe. How will the State or Tribe
handle future needs for development in the area of the ONRW? What role
does EPA play in ensuring that the State or Tribe provides the highest
protection measures to ONRWs? EPA's current thinking is that this ``no
further development in the watershed prohibition'' may be an overly
strict interpretation of the protection required by tier 3 and that a
public debate is necessary to clarify the level or range of protection
that is afforded to a water by classifying it as an ONRW, and how that
level or range should be determined.
One way to remove uncertainty surrounding the implications of ONRW
designations is for States and Tribes to adopt concurrent with the ONRW
the implementation methods for that water body that define what
attributes of the water will be protected and how this will be
accomplished by both point and nonpoint sources. It may make sense for
the regulation to include this requirement in order for all parties
concerned to know the impact on development of such a designation
before adopting an ONRW.
i. Relationship of Tier 3 to the Wild and Scenic Rivers Act.
Additionally some States have not adopted waters as ONRWs when there
has been concern regarding ONRW requirements and the requirements of a
wild, scenic, or recreational water body. Although the Department of
Interior (DoI) founded the antidegradation policy from which the
concept of an outstanding national resource water (ONRW) that EPA
currently uses evolved, an ONRW is different from the Wild and Scenic
Rivers program administered by DoI. ONRWs are designated by the State
or Tribe in their water quality standards. Wild and scenic rivers are
given their designation by Congress or the Department of Interior
pursuant to the Federal Wild and Scenic Rivers Act. The main purpose of
the Wild and Scenic Rivers Act is to keep waters free-flowing. The main
purpose of an ONRW designation is to maintain and protect high quality
waters that constitute outstanding resources due, for example, to their
exceptional recreational or ecological significance, which can include
free-flowing water. EPA does not see any conflict between these two
programs.
b. Tier 3 Implementation. EPA in chapter 4 of the Water Quality
Standards Handbook interprets the ``water quality to be maintained and
protected'' provision of the regulation as requiring no new or
increased discharges to ONRWs and no new or increased discharge to
tributaries to ONRWs that would result in lower water quality in the
ONRWs. The only exception is for short-term and temporary changes. In
contrast, some States, Tribes, and EPA Regions have interpreted this
provision to allow new discharges as long as the water quality is
either maintained or improved. Alternatively, some States, Tribes and
Regions have interpreted water quality in terms of the characteristics
for which the water body was selected to be an ONRW and have strictly
maintained those characteristics while allowing other characteristics
to become degraded. EPA has also allowed a proposed activity that will
result in a new or expanded source where the applicant agrees to
implement or
[[Page 36787]]
finance upstream controls of point or nonpoint sources sufficient to
offset the water quality effects of the proposed activity. This offset
is generally called trading and is accomplished through a TMDL pursuant
to CWA Section 303(d) requirements. Such TMDLs include an appropriate
margin of safety and address, in particular, the uncertainties
associated with any proposed nonpoint source controls, as well as
variability in effluent quality for point sources.
This variability in interpretation has created ONRWs across the
Nation that vary in terms of the stringency of point source controls,
and types of water bodies considered to be ONRWs. Restrictions on
physical changes have also been implemented in an inconsistent manner.
EPA is considering whether the existing ONRW protection program is
addressing an appropriate universe of waters and whether the
flexibility provided under the regulation, in terms of coverage and
protection requirements, needs to be further restricted, maintained, or
expanded. It may make sense to have an ONRW designation which is
permanent and allows no change in water quality and applicable to few
waters while creating a subset of waters which can have some change in
water quality under certain circumstances.
c. Tier 2\1/2\. Several States and Tribes have already created, as
part of their antidegradation policy, a provision that is in between
EPA's recommended tier 2--high quality waters and tier 3-- Outstanding
National Resource Waters, sometimes referred to as Tier 2\1/2\. This
additional tier is given various names, such as Outstanding State
Resource Waters, Outstanding Tribal Waters, Special Protection Waters,
or Water of Exceptional Significance. When it supplements tier 2 and
tier 3 provisions, EPA has accepted this provision as being consistent
with the intent and spirit of the antidegradation policy. Inclusion of
a tier 2\1/2\ within the regulation would encourage States and Tribes
to apply more stringent controls than would be required under tier 2
but with more flexibility to make adjustments in criteria and
permitting decisions than would normally be allowed if the water body
in question were designated as an ONRW. Any additional flexibility that
might be created by a tier 2\1/2\ classification to allow additional
activities that could marginally affect water quality, might not be
necessary where a State or Tribe (or EPA) considers such flexibility to
already exist in the context of the ONRW classification. In commenting
on the flexibility afforded by the tier 2\1/2\ classification,
commenters are urged to state their understanding of the flexibility
currently afforded in the ONRW classification.
Request for Comments on Antidegradation Tier 3
EPA seeks comment on the following questions:
1. Should EPA add definitions of important terms to the ONRW part
of the regulation, including a definition of ``degradation'' which
clarifies that temporary or short-term effects on ONRW waters could be
authorized? Should definitions of ``short-term'' and ``significant''
also be included?
2. Should EPA require States and authorized Tribes to establish
both a process and qualification criteria which would allow the public
to nominate waters for the ONRW designation? Would EPA guidance be
helpful?
3. Should the tier 2\1/2\ antidegradation policy concept be
explicitly recognized in the federal regulation and what, if any,
limits or factors for application of the tier should be included?
4. States (and Tribes) have differing interpretations of the level
of protection afforded ONRWs. Should EPA further specify in the
regulation what maintaining and protecting water quality in ONRWs
means?
6. 40 CFR 131.12 (a)(4) ``Thermal Discharges''
The requirement to prevent potential water quality impairment
associated with thermal discharges contained in Sec. 131.12 (a)(4) of
the regulation is intended to coordinate the requirements and
procedures of the antidegradation policy with those established in the
CWA for setting thermal discharge limitations. Regulations implementing
section 316 may be found at 40 CFR 124.66. The statutory scheme and
legislative history indicate that limitations developed under section
316 take precedence over other requirements of the CWA. EPA is not
requesting comment on this section of the regulation. This provision is
mentioned here only in the interest of completeness.
E. Mixing Zones
1. Background
The current regulation (at 40 CFR 131.13) describes States' and
Tribes' discretionary authority to include, in their water quality
standards, policies that affect the implementation of those standards.
For example, States and Tribes may adopt policies on mixing zones,
variances, and schedules of compliance for water quality-based NPDES
permit limits. If included in their water quality standards or other
implementing regulations, States and Tribes are required to submit such
policies to EPA for review and approval. The policies governing the
implementation of water quality standards are inseparable from the
standards themselves and, consequently, EPA reviews both to determine
whether implementation policies are compatible with the State or Tribal
water quality standards provisions, technically well founded and
consistent with the CWA.
Concerns have been expressed both by the regulated community and
environmental groups over the lack of specificity in State and Tribal
mixing zone policies and implementation procedures adopted under this
general policies provision. These groups believe that this lack of
specificity may result in rather subjective and inconsistent
implementation of water quality standards, from site-to-site. EPA has
also, through its ten regional offices, not always applied uniform
standards in reviewing individual States' and Tribes' mixing zone
provisions.
In encouraging the implementation of water quality management
activities consistent with a broader watershed approach, EPA has
encountered inconsistent implementation of mixing zone provisions
across State and Tribal borders, within whole watersheds, and sometimes
along a single water body. Remedies to water quality problems designed
along watershed boundaries can be limited in their effectiveness as a
result of differing policies, procedures and treatment of the same
water body by different authorities. A certain amount of flexibility
is, however, essential when dealing with complex water quality problems
on a watershed or basin scale. EPA's current thinking is that it is
preferable to be more explicit about where the program requires
consistency and where flexibility is allowed or encouraged.
The current regulation does not articulate any EPA requirements
regarding the content of mixing zone implementation procedures. Rather,
EPA guidance addressing mixing zones, and stream design flows is
contained in several documents, including the Water Quality Standards
Handbook: Second Edition (the Handbook) and the Technical Support
Document for Water Quality-based Toxics Control, March, 1991 (the TSD).
Although program and technical guidance identifies the approaches to
standards implementation which EPA recommends and considers protective
of water quality, guidance is not equally effective at delineating what
constitutes
[[Page 36788]]
minimally acceptable content or the approaches EPA considers to be not
approvable or inconsistent with the CWA. Further, most regulatory
agencies, as well as the regulated community, are most concerned with
what is required rather than what is recommended. Policy or guidance is
not binding whereas regulation is. Guidance is better designed to
provide detailed descriptions of the variety of technically sound
implementation approaches and their underlying scientific basis;
regulation provides the clearest direction regarding required minimal
program content and identification of those components of the program
where flexibility is allowed.
EPA is considering an expansion of the section of the regulation
addressing general policies to provide clear, detailed and specific
direction to States and Tribes on the development and content of mixing
zone policies and implementation procedures. EPA's current thinking is
that greater specificity within this portion of the regulation may be
needed to clarify the minimum necessary elements of State and Tribal
mixing zone policy and implementation procedures. EPA's current
thinking is that this area of the regulation needs to articulate a
clear level of national consistency in mixing zone implementation that
results in a consistent level of protection across the country and at
the same time, where State and Tribal flexibility is not only
encouraged, but possibly essential to program efficiency and accuracy.
2. EPA Policy and Guidance on Mixing Zones
The concept of mixing zones as a regulatory tool to address the
incomplete mixing of wastewater discharges in receiving waters has been
embraced by both EPA and its predecessor agencies as part of a larger
regulatory effort to ensure that point source discharges of wastes do
not impair beneficial uses. EPA interprets the CWA as allowing the use
of mixing zones as long as the provisions addressing toxicity at
section 101(a)(3) are met and the designated uses of the water body as
a whole are protected. One court has considered the application of a
mixing zone in a discharge permit and upheld EPA's use of a limited
mixing zone (See Hercules v. EPA, 598 F.2d 91 (D.C. Cir. 1978)). The
concept of a mixing zone is covered by a series of guidance documents
issued by EPA and its predecessor agencies (see, for example: Water
Quality Criteria (Green Book), Federal Water Pollution Control
Administration, 1968, pp. 29-31; Water Quality Criteria 1972 (Blue
Book), EPA, March 1973, pp. 112-115, 231-232, 403-457; Guidelines for
Developing or Revising Water Quality Standards, January 1973; Chapter
5--Guidelines for State and Areawide Water Quality Management Program
Development, November, 1976; Allocated Impact Zones for Areas of Non-
Compliance, EPA Region 1, October 1986; The Water Quality Standards
Handbook, August, 1994, pp.5-1 to 5-11; Technical Support Document for
Water Quality-based Toxics Control (TSD), March, 1991, pp. 31-34, 56-
60, 69-89).
Many definitions of mixing zones have been offered, differing
primarily by perspective (i.e., engineering, hydrological, ecological,
regulatory) and their application. From a hydrological/engineering
perspective, mixing zones can be defined based upon the recognition of
incomplete mixing of an effluent with its receiving water (e.g., ``that
area or volume of dilution water necessary to reduce contaminant
concentrations to some acceptable level or to a totally mixed
condition''). Biologically, mixing zones can be defined based on the
premise that surface water quality criteria can be exceeded under
limited circumstances without causing unacceptable toxicity or, more
broadly, impairment of the designated beneficial uses (e.g., ``the area
contiguous to a discharge where receiving water quality is not required
to meet water quality criteria nor other requirements applicable to the
receiving water'').
EPA's policy on the use of mixing zones has evolved since its early
recognition within general water quality guidance, primarily in
association with the institution and evolution of the NPDES permit
program (e.g., the TSD). Initially, guidance emphasized the need to
ensure that the biological integrity of the aquatic community in the
receiving stream was protected and that such determinations must be
based on site-specific evaluations. In the late 1980's EPA and
authorized NPDES States began increasing the development and issuance
of water quality-based effluent limits. With this increase, came a
demand for widely applicable national guidance to support those
programs. EPA and States, in essence, needed wasteload allocation and
water quality-based permit limit derivation methods that were
relatively simple to use and could be implemented with little site-
specific data. EPA met this demand by issuing revised guidance (the TSD
and Handbook, cited above, are examples) and by accepting a wide range
of State mixing zone practices. As a result, mixing zone provisions
have become less prescriptive than earlier guidance that envisioned
data rich, site-specific studies, and more reliant on often cursory
evaluations, general mixing assumptions, and best professional
judgement.
EPA's current policy addresses mixing zones as allocated impact
zones (AIZs) where certain numeric water quality criteria may be
exceeded as long as: there is no lethality to organisms passing through
the mixing zone, there are no significant risks to human health, and
the designated and existing uses of the water body are not impaired as
a result. These AIZs or mixing zones, if disproportionately large,
could unacceptably impact the integrity of the aquatic ecosystem and
have unanticipated ecological consequences on the water body as a whole
resulting in impairment of the designated or existing uses. Therefore,
EPA's policy has emphasized a holistic approach to mixing zone
regulation which considers location, size, shape, outfall design and
in-zone quality. Mixing zone guidance produced by EPA since 1972 has
consistently emphasized the need to protect both nonmotile benthic and
sessile organisms in the mixing zone as well as swimming and drifting
organisms (Water Quality Criteria 1972). States and Tribes, however,
have focused primarily, if not exclusively, on the protection of
swimming and drifting organisms and the need to provide ``zones of
passage'' within waters with mixing zones. In its dependence upon
conditions protective of swimming and drifting organisms to define
mixing zones, this approach results in an incomplete implementation of
the original concept supporting mixing zones. As originally designed,
EPA's mixing zone policy provided for the prevention of lethality to
swimming and drifting organisms by limiting the size of the mixing zone
and to nonmotile organisms by limiting the placement or location of
mixing zones.
Although existing EPA guidance on the implementation of mixing
zones (cited above) is quite detailed, at present, the regulation
itself simply provides that States and Tribes may adopt, as part of
their water quality standards, mixing zone policies and that such
policies are subject to EPA review and approval (40 CFR 131.13). In
addition, EPA may separately review individual State and, once approved
to administer NPDES, Tribal mixing zone determinations as part of the
wasteload allocation and NPDES permit review process, outside the
standards adoption and review process to ensure appropriate
implementation of the State's mixing zone policy.
[[Page 36789]]
EPA is considering expanding the current provisions at 40 CFR
131.13 addressing State and Tribal development of mixing zone policies
within their water quality standards program to address the content and
design of those policies.
3. State and Tribal Mixing Zone Policies
While there are advantages to the more flexible general approach
adopted in the late 1980's, the generality of the current regulation
has led to some uncertainty as to what constitutes an approvable mixing
zone policy. Because the regulation lacks detailed requirements
concerning EPA's standards of review of State and Tribal mixing zone
provisions, EPA is considering changing the language regarding State
and Tribal adoption of mixing zone policies to address specifically the
content of such policies. EPA's current thinking is that greater
specificity would provide for increased public participation in State,
Tribal and Federal decision-making; a clearer understanding by the
State, Tribe and public of what EPA considers an approvable mixing zone
policy; a reduction in the number of NPDES permit appeals and
objections based on differing interpretations of a State or Tribal
mixing zone policy; and a more consistent review of State and Tribal
submissions by EPA itself.
Fundamental to any such policy, EPA is considering requiring States
and Tribes to indicate explicitly in their water quality standards
whether or not they allow mixing zones for each of the various uses
designated for a given water body. Such provisions could address mixing
zones applied to either acute or chronic aquatic life and other water
quality criteria (e.g., public water supply, livestock watering,
wildlife protection, etc.). Under this approach, if the State or Tribe
does not explicitly authorize mixing zones, then no mixing zones would
be allowed in State or Tribal waters, and all applicable criteria would
have to be met at the end-of-pipe. (Memorandum from Robert Perciasepe,
Assistant Administrator for Water to Water Program Directors, Regions
I-X, Subject: EPA Guidance on Application of State Mixing Zone Policies
in EPA-Issued NPDES Permits, August 6, 1996). Alternatively, States and
Tribes could determine that such prohibitions would be applied to only
a subset of uses or pollutants rather than across all use categories
and pollutants. Some States or Tribes have used this approach to
prohibit mixing zones in their highest use classes (e.g., class AA),
while allowing mixing zones in more highly impacted watersheds (e.g.,
class C or D waters).
States and Tribes could also be required to specify the conditions
under which mixing zones are allowed in each site-specific application
and the limitations to those applications (e.g., size, shape, length,
placement, etc.). In addition, States and Tribes could be required to
identify any circumstances, pollutants, locations or conditions for
which the use of mixing zones is prohibited. States and Tribes could
specify circumstances where only chronic mixing zones would be allowed
(i.e., no acute mixing zone or zone-of-initial dilution) and
circumstances where acute and/or chronic mixing zones would be
prohibited. Current EPA guidance, for example, recommends States and
Tribes consider prohibition of mixing zones when bioaccumulative
pollutants are present in the discharge or where an effluent is known
to attract biota. Other circumstances where mixing zone prohibitions or
location restrictions might be appropriate include areas used by
aquatic life for breeding or feeding, locations of shellfish beds,
locations of critical habitat for threatened and endangered species,
across tributary mouths, shallows, near shore areas and in areas of
critical habitat.
This change would clarify in the regulation the State and Tribal
general authority to provide mixing zones, the scope of that authority,
and the site-specific factors evaluated by States and Tribes when
deciding whether a mixing zone is authorized in each individual case.
EPA is considering making this potential clarification to the
regulation, its implications, and how mixing zone policies can be
designed to better support and foster a watershed management framework.
4. Mixing Zone Requirements
Some States and Tribes that have adopted mixing zone provisions
within their water quality standards have not specified mixing zone
requirements (e.g., water quality within mixing zones, the allowable
size of mixing zones, etc.) under their mixing zone policies. EPA is
therefore considering including as regulatory requirements certain
specifications derived from EPA's guidance on mixing zones. Regarding
policy content, EPA might revise the regulation to require that State
and Tribal mixing zone policies address a minimum number of elements.
Those required elements might include provisions that: identify
conditions and circumstances (e.g., particular locations) when mixing
zones are not permitted; identify any pollutants or classes of
pollutants for which mixing zones are prohibited; identify the
mechanisms to be used to ensure that mixing zones do not impinge on
ecologically or recreationally sensitive areas; identify the mechanisms
to be used to determine complete and incomplete mixing of effluent and
receiving water; identify conditions when a mixing analysis is
required; identify default design flows for implementing criteria;
identify maximum allowable mixing zone size and configuration, as well
as how mixing zones dimensions are determined; specify what water
quality conditions must be met within mixing zones; state whether zones
of initial dilution are allowed; and state whether there are special
conditions established for bioaccumulative pollutants.
Identification in the regulation of minimum elements of State or
Tribal mixing zones procedures would establish the basis for EPA review
and approval of State and Tribal mixing zone provisions. It would also
facilitate the review of individual mixing zone determinations made
under the wasteload allocation/permit approval process by EPA, other
agencies and the public. This would not significantly change EPA's
guidance or current approach to mixing zone policies. Rather, it would
clarify and codify the basis by which EPA will review and approve or
disapprove State and Tribal mixing zone policies and their site-
specific implementation through NPDES permits.
As discussed previously, EPA's mixing zone guidance is premised
fundamentally on the prevention of lethality within the mixing zone and
siting such that areas of critical habitat are avoided, resulting in
the protection of designated uses. One aspect of this guidance is that,
for aquatic life uses, water quality within the mixing zone should be
such that, at a specified concentration of a contaminant (i.e.,
magnitude), any ``swimming or drifting'' organism would not remain in
the mixing zone long enough to receive an exposure that is sufficiently
long (i.e., duration) to cause lethality. If the combination of the
concentration of a given pollutant or the combined effect of multiple
pollutants (e.g., whole effluent toxicity) in a discharge and the
duration of exposure to that concentration are low enough, there is no
lethality within the mixing zone, and the criteria (magnitude and
duration components together) are met.
This approach, however, only provides protection in situations in
which water column organisms pass in and out of the mixing zone. This
interpretation does not adequately
[[Page 36790]]
protect stationary or sessile organisms within the mixing zone;
organisms that remain within the mixing zone for extended periods
because the mixing zone extends into feeding or breeding areas or
critical habitat (e.g., tributary mouths, shallows, shoreline habitat
in large, fast-flowing rivers); critical habitat areas for endangered
or threatened species; or instances where mixing zone conditions
attract organisms. EPA's mixing zone policy and guidance address those
instances where the provisions protecting swimming and drifting
organisms are not adequate to protect nonmotile benthic and sessile
organisms or critical habitat areas by limiting the location, size and
shape of mixing zones. In some instances, this policy has been
implemented in a fragmented manner. In such instances, these latter
restrictions to mixing zone placement are inadequately addressed. EPA
always has discretion to object to, and take over if necessary, permits
that provide site-specific mixing zones in cases where such mixing
zones would fail to protect all aspects of designated uses. However,
oversight of individual permits is not an efficient approach to
resolving program-level issues. To clarify the meaning of its policy
and ensure a more complete implementation of protective mixing zone
provisions, EPA is considering changes to the regulation.
EPA could require that State and Tribal mixing zone policies
specifically identify prohibitions (where appropriate) or limit mixing
zones where necessary to protect existing or designated uses. Some
States and Tribes already include prohibitions against the use of
mixing zones where they could intrude upon public drinking water supply
intakes or public swimming beaches, or where mixing zones prove to be
attractive to aquatic life or wildlife (e.g., water temperature). EPA
might require that State and Tribal mixing zone provisions specifically
address instances such as these where restrictions on mixing zones are
appropriate. Additionally, EPA is considering requiring that State and
Tribal water quality standards include a description of the State's or
Tribe's methodology for specifying the location, geographic boundaries,
size, shape and in-zone quality of mixing zones.
EPA could also clarify its current policy that an approvable mixing
zone methodology must be scientifically defensible and ensure the
protection of designated uses in the water body as a whole. This would
require that the methodology, at a minimum, be sufficiently precise to
support consistent regulatory actions (e.g., an NPDES permit). EPA is
considering this change to ensure that State and Tribal mixing zones do
not adversely affect the integrity of State and Tribal waters and to
address inconsistent allocation of mixing zones from site-to-site.
Under this approach, for example, when a State or Tribe assumes that
either complete or incomplete mixing occurs, the State's or Tribe's
implementation procedure could require the analyses supporting the mix
assumption to be documented in the record (e.g., permit fact sheet).
EPA is considering the need for additional language in the water
quality standards regulation to clarify the essential elements of State
or Tribal mixing zone provisions and, alternatively, whether such
language would be better established in guidance. EPA's current
thinking is that a certain amount of professional judgement is
necessary in making site-specific mixing zone determinations and that
clarifications to the regulation regarding the minimum mixing zone
policies and implementation procedures should not preclude such
flexibility. However, the policy and implementation procedures should
be clarified so that the guidelines and framework for making site-
specific mixing zone determinations are clear to everyone.
5. Mixing Analyses
The above discussion focuses on establishing State and Tribal
mixing zone policies and procedures. The following discussion addresses
the application of such procedures in individual permitting decisions.
Where point source discharges mix in a slow or ``incomplete''
manner with receiving waters and the State or Tribe has authority to
provide a mixing zone, EPA guidance recommends that a mixing zone
analysis be incorporated into the derivation of water quality-based
effluent limits (WQBELs) in NPDES permits. The mixing zone analysis
should demonstrate compliance with State or Tribal mixing zone
requirements (e.g., size, shape, location and in-zone quality) that are
included in the water quality standards. Providing a mixing zone in
incomplete-mix situations acknowledges the mixing behavior of the
discharge and limits excursions above criteria to a specified zone.
Where a discharge mixes with the receiving water in a rapid and
``complete'' manner, by definition a mixing zone analysis is not needed
and an evaluation of the assimilative capacity of the receiving water
and a dilution allowance based on stream design flow conditions
specified in the State or Tribal water quality standards is often
incorporated into the derivation of WQBELs.
Presently, all State-issued NPDES permits are reviewable by EPA.
EPA may object to individual permits and assume authority to issue such
permits. When EPA is the permit issuing authority, it must follow the
applicable State or Tribal water quality standards and ensure that any
water quality-based effluent limits in the permit are derived from and
comply with the applicable State or Tribal water quality requirements.
A permit that does not include a defensible mixing zone analysis might
not fully protect downstream designated uses. A common example is where
a discharge mixes slowly (i.e., incomplete mixing is occurring), but
the permit limit is based on an assumption that the entire design flow
of the stream rapidly and completely dilutes the effluent. When this
does not occur and not all of the dilution water mixes rapidly with the
effluent discharge, the result may be a lengthy downstream plume (i.e.,
mixture of effluent and surface water) with water quality
characteristics that exceed applicable chemical-specific or toxicity
criteria, are potentially lethal to aquatic life, and may impair the
designated use. Such plumes are of concern because:
(1) Chemical-specific criteria, ambient toxicity criteria or other
narrative criteria may not be achieved in the extended plume;
(2) Effluent plumes can extend far downstream, causing impact
beyond the limited area of a mixing zone and resulting in use
impairment;
(3) There may be intakes for public drinking water systems located
downstream, but within reach of an extended plume;
(4) Effluent plumes may be located along the shore in shallow
waters that are critical nursery areas for sensitive species and which
constitute important or critical habitat, particularly in large,
channelized rivers;
(5) Aquatic life might be attracted to the plume because of its
temperature differential or other characteristics;
(6) Threatened or endangered species may reside within or near the
plume area, and
(7) Additional dischargers may be located downstream and the
cumulative effects of all discharges may not be adequately considered,
particularly regarding unintended overlapping plumes.
EPA believes the rate of ambient mixing and the complete versus
incomplete mix decision is a critical but frequently overlooked
component of water quality-based permitting.
[[Page 36791]]
Although a mixing zone analyses requires site-specific information and
additional resources, EPA believes that the approach currently followed
by some States and Tribes might be too simplistic, might allow
lethality within areas of critical habitat or ecological importance and
may not fully protect designated uses. EPA's current thinking is that
the regulation should be made more explicit as to the circumstances
under which mixing zones must be supported by site-specific data and
analysis. EPA is considering the need for specific requirements within
the regulation governing the development and content of mixing zone
analysis procedures as part of State and Tribal implementation
procedures.
6. Narrative Criteria for Mixing Zones
Historically, States have relied on narrative criteria as a means
to provide baseline protection for water quality, to address toxicity
from combinations of pollutants or unknown pollutants through whole
effluent toxicity testing and limits, and to control pollutants for
which there are no chemical-specific criteria available. EPA has
consistently maintained that prevention of nuisance conditions (e.g.,
materials that will settle to form objectionable deposits, floating
debris, oil, scum, foam and other matter, toxic conditions, etc.),
through the application of narrative criteria, apply to all waters, at
all times, including mixing zones. Despite this long-standing policy,
EPA is unaware if, in practice, States and Tribes have had any
difficulty ensuring the maintenance of these narrative criteria within
mixing zones. EPA is interested in comment which might identify any
instances where the application of narrative criteria has created
difficulties for States and Tribes implementing these provisions in
mixing zones.
In addition, EPA has traditionally interpreted these narrative
``free froms'' as including a prohibition against lethality in all
waters, including within mixing zones. However, lethality is a non-
conservative endpoint for measuring toxicity. Section 101(a)(3) of the
CWA establishes a goal of prohibiting ``the discharge of toxic
pollutants in toxic amounts'' which could be interpreted as applying to
chronic as well as acute toxicity. EPA guidance on appropriate water
quality within mixing zones also recommends that ``the total time-
toxicity exposure history must not cause deleterious effects in exposed
populations of important species, including post-exposure effects''
(EPA, 1973). EPA is considering how such an interpretation (i.e.,
applying chronic toxicity endpoints to water quality within a mixing
zone) could be implemented in the context of the application of
narrative criteria within a mixing zone.
Guidance developed by EPA in 1985 (TSD) established a rationale for
allowing zones-of-initial-dilution (ZIDs) or acute mixing zones. That
guidance limited the use of ZIDs to extremely small areas of the
receiving water under limited conditions and to discharges using rapid
diffusers which produce effluent discharge velocities exceeding 10 feet
per second. That guidance was premised on the rationale that organisms
would be physically precluded from maintaining a position within the
ZID, thus preventing lethal exposures. Benthic and sessile organisms
were also protected where ZID placement was controlled and directed
away from such critical areas (e.g., near shore, shallows, etc.). In
addition, EPA reasoned, high rate diffusers achieve compliance with
both acute and chronic criteria within a smaller area, utilizing less
receiving water volume for dilution than other discharge designs.
Consequently, high rate diffusers are believed to provide greater
protection of water quality by their rapid dispersion of effluent
within a smaller volume of surface water. Where acute criteria are not
applied at the end-of-pipe, current EPA guidance provides for a number
of alternative means of protecting against lethality in a mixing zone,
even in situations that do not rely on high rate diffusers.
Alternatives to requiring compliance with acute criteria at the end-of-
pipe or employing a high-rate diffuser to ensure compliance ``within a
very short distance from the outfall'' require a significant amount of
site-specific data. Such site-specific data could be requested of NPDES
permit applicants. It is EPA's experience that the collection of this
kind of data does not occur on a routine basis. EPA is interested in
public comment on the relationship between ZIDs or acute mixing zones
and narrative criteria prohibitions against lethality and States' and
Tribes' experiences with the application of acute mixing zones under
varying site-specific and discharge-specific conditions. EPA is also
interested in comments on whether the water quality benefits of using
high rate diffusers justify potentially detrimental effects on stream
bed or shore line habitat.
7. Mixing Zones for Bioaccumulative Pollutants
States and Tribes should exercise caution when evaluating whether a
mixing zone is appropriate in cases where bioaccumulative pollutants
are present. The impacts of bioaccumulative compounds may extend beyond
the boundaries of a given mixing zone with resulting impairment of a
water body's designated uses, particularly where stationary species
(e.g. shellfish) are present, where uncertainties exist regarding the
assimilative capacity of a water body or where bioaccumulation in the
food chain is known to be a problem. Sediment contamination has also
become a major concern in both flowing and non-flowing water bodies.
Concerns about sediment contamination require additional attention
since typical mixing zone evaluations focus only on water column
toxicity. The effects of persistent and bioaccumulative pollutants may
not be detected for some distance from the point of discharge, well
outside the mixing zone, or possibly not in the water column at all.
Some members of the public have expressed concern regarding the use of
mixing zones in situations where bioaccumulative pollutants are present
in a discharge and have urged EPA to develop specific regulatory
requirements prohibiting the use of mixing zones where these pollutants
are present.
Mixing zone policies are developed to address complete and
incomplete mixing conditions associated with point source discharges.
These policies identify whether mixing zones are allowed and define how
a State or Tribe will limit the amount of surface water allocated to
mixing under a variety of circumstances. These circumstances include
considerations specific to the effluent and pollutants discharged
(e.g., toxicity, solubility) and to the water body receiving the waste
(e.g., shallow, flowing or non-flowing, high flow or low flow, critical
habitat). The potential for bioaccumulation problems can depend on a
number of site-specific factors and the use of mixing zones for
bioaccumulative pollutants may be best dealt with on a site- or basin-
specific basis. EPA's mixing zone guidance emphasizes that the
determination by a State or Tribe that a mixing zone is appropriate
must be preceded by a separate determination that there is available
assimilative capacity in the receiving water. Localized water quality
concerns are to be balanced with the larger scale issue of overall
pollutant loading to the entire water body or segment. Perhaps concerns
about the fate and transport of bioaccumulative pollutants are more
effectively addressed under total maximum daily load (TMDL) development
and determinations of assimilative capacity which incorporate
information on water
[[Page 36792]]
column, sediment and tissue contamination. EPA is considering the
appropriateness of using mixing zones when controlling for
bioaccumulative pollutants.
As discussed in more detail in Section C of this Notice, EPA has
recently developed methodologies for deriving sediment quality criteria
for non-ionic organics and metals and has proposed sediment quality
criteria for five organics. In addition, EPA is working on
implementation procedures or a ``user's guide'' for these sediment
criteria which will address risk management decisions such as the
application of mixing zones.
The regulatory impact of special restrictions on mixing zones for a
particular family of pollutants is largely determined by how that
family of pollutants is defined within the regulation. The issue of
definition of bioaccumulative pollutants is also addressed in the
discussion of water quality criteria in Section C of this notice.
In its Great Lakes Guidance, EPA established a twelve year phase
out of mixing zones for existing discharges of bioaccumulative
chemicals of concern (BCCs) in the Great Lakes Basin and a ban on such
mixing zones for new discharges (effective March 1997). The Great Lakes
Guidance also allowed States and Tribes to establish limited exceptions
to the mixing zone phase-out for existing discharges based on water
conservation or economic and technical considerations. The general
prohibition on mixing zones for BCCs was established largely because of
the persistent and toxic nature of even minute amounts of BCCs in the
environment; an effect amplified in the Great Lakes by the tendency of
the Lakes to act as ``sinks'' for pollutants discharged to the Great
Lakes Basin. In addition, there are documented problems with effects of
BCCs in Great Lakes waters (e.g., contamination of Great Lakes salmonid
sport fisheries with PCBs and Basin-wide mercury contamination). The
Great Lakes Guidance provision phasing out mixing zones for BCCs
reflected the Agency's thinking that, in general, mixing zone
allowances for BCCs are not appropriate.
On June 6, 1997, the United States Court of Appeals for the
District of Columbia Circuit issued its decision in American Iron and
Steel Institute, et al. v. EPA, 115 F.3d 979 (D.C. Cir. 1997). The
Court's decision upheld the Great Lakes Guidance on all but three
issues. One of these three issues was the phase out of on mixing zones
for BCCs. Specifically, the Court vacated the final Guidance insofar as
it would eliminate mixing zones for bioaccumulative chemicals of
concern (BCCs). While the Court acknowledged the possibility of
environmental benefit of the mixing zone provisions, the Court found
that EPA failed to show that the provisions were justified in light of
the costs. EPA continues to support elimination of mixing zones for
BCCs within the Great Lakes Basin wherever it is technically and
economically feasible to do so. Thus, EPA intends to propose
reinstating this provision in the near future.
8. Stream Design Flow Policies
States and Tribes typically identify, within their water quality
standards, stream design flow conditions to implement numeric water
quality criteria. The stream flow conditions are typically expressed as
predictable low flow conditions below which numeric water quality
criteria do not apply. Examples of commonly used stream design flows
include: the lowest seven consecutive day average stream flow that has
the annual probability of occurring once in ten years (7Q10); the
lowest single day stream flow that has the annual probability of
occurring once in ten years (1Q10); and the harmonic mean stream flow.
The stream design flows typically employed with aquatic life criteria
(i.e., 7Q10 and 1Q10), sometimes referred to as critical low flows or
drought flows, are intended to define stream flow conditions at and
above which the designated uses are presumed to exist and applicable
numeric water quality criteria must be met in order for those uses to
be attained. The underlying concept is that these low flow events are a
part of the dynamic hydrologic character of all flowing water bodies.
Low flow conditions present special challenges to the integrity of the
aquatic community. Even under these low flow conditions, however, the
long-term beneficial use could be maintained unless toxic conditions
stress the aquatic community beyond its ability to tolerate and
recover.
In practice, stream design flows serve several purposes in addition
to defining the minimum stream flows below which numeric water quality
criteria do not apply. Many States and Tribes have used the stream
design flows, or fractions thereof, to define the amount of stream flow
that can be assumed to always be available to dilute effluent. Under
rapid and complete mixing conditions, the entire stream design flow is
used as the basis for determining permit limits. That is, no mixing
zone is necessary. Under slow or incomplete mixing conditions, where a
mixing zone is necessary, fractions of stream design flow are used to
calculate assimilative capacity on which permit limits can be based; in
other words, to crudely define the mixing zone. Often this default
approach is used by regulatory agencies in response to limited
resources, lack of site-specific information and the time pressures of
permit reissuance. This default approach to defining the mixing zone
is, in EPA's view, acceptable as long as the mixing of the effluent in
the receiving water occurs away from critical areas and the amount of
dilution provided is conservative for a broad range of possible
effluent/receiving water dilution scenarios. However, where a complete
mixing assumption does not hold true, such as where an effluent plume
does not disperse quickly, and too much of the receiving water is
allocated for dilution, this default assumption approach will not
ensure attainment of water quality standards because numeric water
quality criteria will be exceeded in a larger area than anticipated
(outside the regulatory mixing zone). The default use of fractions of
stream design flows instead of more exacting mixing zone determinations
is not always appropriate. In some instances, the effluent plume may
never fully mix with the specified amount of receiving water, resulting
in plumes where criteria are exceeded extending far beyond what may be
considered protective of designated uses or allowed under standards.
EPA has recommended that site-specific information on the mixing
characteristics of a discharge be collected to verify the level of
protection assumed to be provided to a water body using default mixing
zone provisions.
EPA believes it is important for individual States and Tribes to
make consistent dilution allowance decisions from one site to the next.
Requiring States and Tribes, as part of their water quality standards,
to specify how dilution allowances under complete and incomplete mix
situations will be established may be an appropriate way to ensure
consistent decision-making.
To best define dilution allowances for implementing water quality
standards, it is useful to define both stream design flows and effluent
design flows. In particular, a distinction should be made between the
stream design flows to be used for different ambient water quality
criteria (e.g., aquatic life acute, aquatic life chronic, human health
carcinogen). In addition, effluent design flows may vary in some cases
based upon seasonal changes or production cycles. Stream design flows
may be applied as a maximum dilution allowance or adjusted in
individual cases based on
[[Page 36793]]
any stream-specific or pollutant-specific considerations. Stream design
flows, if they are used, must correspond to the duration and frequency
components of the ambient water quality criteria contained in the State
or Tribal water quality standards. Currently, States and Tribes must
justify the scientific validity of their stream design flow policies
where they differ from EPA's recommendations. States and Tribes may
also establish specific guidelines for restricting dilution allowances
in individual cases (e.g., States and Tribes may adopt special
restrictions on dilution allowances for human health criteria where a
discharge is within 2 miles of a drinking water intake).
EPA's Great Lakes Guidance and its Technical Support Document for
Water Quality-Based Toxics Control identify acute and chronic stream
design flows to be utilized in drafting permit limits. The Guidance
establishes a 7Q10 or 4-day, 3-year biologically-based stream design
flow for implementation of the aquatic life criterion continuous
concentration (chronic criteria); a 1Q10 for the implementation of the
aquatic life criterion maximum concentration (acute criteria); harmonic
mean flow for implementation of human health criteria; and a 90Q10 for
the implementation of wildlife criteria.
In cases where complete and rapid mixing of effluent with receiving
water does not occur, site-specific mixing determinations must be made.
Although the selection of fractions of stream design flows for the
assignment of available dilution for point source discharges does
affect the size of the regulatory mixing zone, such default assignments
are not hydrologically linked to the actual behavior of the effluent
plume in the receiving water, may not protect swimming and drifting
organisms or sessile or benthic organisms and are not equivalent to a
mixing analysis. There may be other instances where the reliance on a
fixed percentage of flow or cross-sectional area of the receiving
stream in lieu of an actual mixing analysis may not reflect the mixing
behavior of an effluent. In some high dilution situations, there may be
more rapid dilution occurring than is assumed in dilution calculations.
If complete and instantaneous mixing actually occurs, using less
than 100% of the design flow can be a means of accounting for
situations where the actual assimilative capacity of the water body is
unknown. States and Tribes typically determine water body assimilative
capacity based on ambient background concentration of a pollutant, when
data on such concentrations is available. The assimilative capacity is
the difference between the background level of a pollutant and the
highest level that would comply with the water quality criterion. Where
information on all sources of a given contaminant to a specific water
body is incomplete, or where the State or Tribe wishes to reserve
assimilative capacity for the future, States and Tribes should allocate
less than 100% of the assimilative capacity of that water body at
design flow by utilizing less than 100% of the design flow for
dilution. EPA is interested in comment addressing the use of these
stream design flows or fractions of stream design flows in setting
mixing zones and in reserving assimilative capacity in a water body.
The Great Lakes Guidance allows States and Tribes to use default
assumptions for available dilution in the absence of site-specific
mixing data. The default dilution assumption for open waters (e.g.,
lakes) provides for ten-to-one dilution. The Guidance also allows for a
demonstration to determine actual mixing zone water quality, size,
placement and behavior. Under the Guidance, for open waters, in no case
can mixing zone size exceed that area in which discharge-induced mixing
occurs. As a default, the Guidance restricts the mixing zone for
protection of aquatic life from acute effects (i.e., the dilution
allowed in calculating limits based on an acute aquatic life criterion
or CMC) to 2 parts receiving water to 1 part effluent, at water body
design flow or volume.
As a default for implementing criteria for the protection of
aquatic life from chronic effects (CCC) in flowing waters (e.g., rivers
and streams), the Great Lakes Guidance allows States and Tribes to use
up to 25% of the design flow for dilution. If a site-specific mixing
analysis is performed, a larger mixing zone may be established. Mixing
zones for acute aquatic life criteria in flowing waters are limited to
the final acute value or FAV (2 x the acute criterion) just as in open
waters. EPA is interested in comment on whether this FAV default
``cap'' approach is appropriate for waters outside the Great Lakes
Basin.
As stated above, the Great Lakes Guidance allows increases above
the default mixing zone allowances when site-specific mixing zone
analyses are conducted. These demonstrations compile data on the mixing
behavior of the effluent at a particular site (e.g., the size, shape
and location of the mixing zone). The Guidance also required that
mixing zones maintain existing and designated uses and comply with
narrative water quality criteria (e.g., ``free froms'').
The Great Lakes Guidance also specifies that mixing zones may not
jeopardize the existence of threatened or endangered species or their
critical habitat.
EPA advocates the watershed approach to water quality protection.
For the water quality standards program, the emphasis has been toward
refinement of designated uses and incorporation of new and emerging
sophisticated and integrated analytical tools as a means to better
characterize the ecological condition of water resources and more
effectively protect designated uses (see section I(A) ``General Purpose
and Vision'' of this document). The development and implementation of
mixing zone policies by States and Tribes constitutes risk management
at the sub-watershed level. EPA has consistently emphasized the need to
ensure that State and Tribal mixing zone provisions protect the
designated uses of receiving waters. Site-specific data collected
through a mixing zone analysis will ensure that designated uses will be
protected the loss of ecological integrity from the discharge of
effluents will be prevented. An emphasis on the protection of
designated uses and maintenance of ecological integrity is essential to
the watershed approach. The watershed approach requires increased site-
specific information on local aquatic systems and an assessment of the
impact of all discharges to local ecosystems. The watershed approach
also depends upon the meaningful involvement of local communities in
risk management decision-making. Explicit, clear implementation
policies provide the public with the information necessary to
understand decisions being made by regulators and the impact of those
decisions on local resources.
Request for Comments on Mixing Zone Policies and Implementation
Procedures
EPA requests comment on the following questions:
1. Should the regulation be changed to expressly require States and
Tribes to include a statement in their water quality standards
indicating whether mixing zones are allowed?
2. Should the regulation be changed to expressly require States and
Tribes to specify procedures by which mixing zone decisions for
individual discharges would be made?
3. Should the regulation be modified to identify the minimum
requirements or elements for State and Tribal mixing zone policies
(including size, location, and methodologies)?
[[Page 36794]]
4. Consistent with current EPA policy, should the regulation
explicitly require narrative criteria to apply in mixing zones?
5. Should the regulation require States and Tribes to identify in
their mixing zone provisions what minimum water quality conditions are
required within mixing zones?
6. Are there any circumstances, types of pollutants or water body
types (e.g., wet weather discharges) where mixing zones should be
restricted or prohibited?
7. Should mixing zones for bioaccumulative pollutants be
prohibited? If so, under what circumstances? Should such prohibitions
be addressed on a water body- or basin-specific basis? Should EPA allow
exceptions to any such prohibitions?
8. Should the regulation require States and Tribes to specify
procedures and decision criteria for evaluating complete and incomplete
mixing?
9. Should the regulation require different mixing zone/dilution
procedures for complete and incompletely mixed situations?
10. Should an assumption of rapid and complete mixing within State
and Tribal implementation procedures be prohibited except where a
defensible technical rationale is included in each site-specific
determination?
11. Should the regulation explicitly allow the use of default
mixing zone assumptions based on fractions of stream design flow in the
absence of site-specific data?
12. Should the regulation be clarified, consistent with current EPA
policy, to require States and Tribes to identify the water body design
flows or volumes upon which their water quality standards are based?
F. Wetlands as Waters of the United States
The current water quality standards regulation contains no
definition of ``waters of the United States,'' although this term is
used in the definition of ``water quality standards.'' The phrase
``waters of the United States'' has been defined elsewhere in Federal
regulations, including regulations governing the National Pollutant
Discharge Elimination System (NPDES). That definition at 40 CFR 122.2
includes wetlands whose use, degradation or destruction could affect
interstate commerce and wetlands adjacent to other waters of the U.S.
However, because this definition does not appear in 40 CFR 131, some
have questioned whether Part 131 applies to wetlands. EPA's position is
that the Part 131 regulations do apply to wetlands. EPA is considering
including the definition for ``waters of the United States'' under the
standards regulation as well, or, at a minimum, cross-referencing the
definition at 40 CFR 122.2 as a means of clarifying that the existing
regulation applies to wetlands that fall within the definition of
waters of the United States. Currently, EPA plans no review or revision
of the existing definition of ``waters of the United States'' as part
of any revision of the water quality standards regulation. Therefore,
under the ANPRM, EPA is interested in comment limited to whether the
existing definition should be included within the standards regulation
in some form.
EPA believes that some States or Tribes may not be providing the
same protection to wetlands that they provide to other surface waters,
including designation of attainable uses consistent with the CWA and
assignment of protective water quality criteria. Therefore, EPA wishes
to emphasize that wetlands require the same protection under water
quality standards as other waters of the U.S. Section 303 of the CWA
requires the protection of all ``waters of the U.S.'' under standards.
Addition of the definition of ``waters of the U.S.'' under a revision
of the regulations would not constitute an expansion of authority or
application, but merely a clarification of those requirements already
contained within the CWA. Treatment of jurisdictional issues would not
be affected by such a revision, including treatment of waters
constructed as waste treatment systems (e.g., wetlands constructed for
wastewater treatment). Notwithstanding protection of wetlands under
other provisions of the CWA (e.g., Section 404), Section 303 clearly
establishes a baseline level of protection applicable to all waters.
Further, it is this treatment under water quality standards which
provides for protection of wetlands as applied under Section 404.
Necessary components of water quality standards for wetlands are
designated uses and criteria, as defined in 40 CFR 131.6. EPA
recognizes that uses and criteria should reflect the unique physical,
chemical and biological characteristics of wetlands. States and Tribes
are encouraged to develop and adopt appropriate classification systems
which provide protection of beneficial uses of wetlands through the
application of physical, chemical and biological criteria. EPA also
recognizes that certain parameters, conditions or even pollutants may
be most appropriately addressed by criteria which specifically reflect
differences between wetlands and other surface waters.
Request for Comments on Wetlands
EPA requests public comment on the following questions:
1. Should ``waters of the United States'' be defined in the water
quality standards regulation?
2. Should EPA provide explicit reference in the regulation to the
applicability of water quality standards to wetlands?
3. Do the current regulation and existing guidance provide the
necessary regulatory clarity, technical tools, and incentives for
States and Tribes to develop appropriate standards for wetlands?
4. Are specific programmatic changes needed to facilitate the
development of water quality standards for wetlands?
G. Independent Application Policy
1. Introduction
Section 101(a) of the Clean Water Act states: ``The objective of
this Act is to restore and maintain the chemical, physical, and
biological integrity of the Nation's waters.'' To this end, States and
Tribes designate single or multiple uses for their waters including
aquatic life protection. For the purposes of assessing the extent to
which aquatic life is protected and whether actions to protect aquatic
life are needed, the CWA requires that States and Tribes adopt water
quality criteria necessary to support designated uses. For waters where
aquatic life protection is an applicable designated use, the extension
of the CWA requires States and Tribes to adopt criteria protective of
aquatic life. Taken together, chemical, physical, and biological
integrity define the overall ecological integrity of an aquatic
ecosystem. Over the years, EPA, States and Tribes have developed
various tools to assess the extent to which water quality attains this
objective. These tools have been developed to build on and support the
capabilities of each other and provide a comprehensive set of elements
necessary for implementing water quality standards and achieving the
objective of the CWA. EPA policy and guidance recommends that States
and Tribes use chemical-specific, toxicity, and biological criteria to
monitor and protect designated uses. In 1991, EPA established its
policy on independent application (U.S. EPA, transmittal memorandum of
final policy on biological assessment and criteria from Tudor Davies to
Regions, June 19, 1991). EPA's independent application policy speaks to
how assessments based
[[Page 36795]]
on these three kinds of criteria are to be integrated into all forms of
water quality management decision-making. EPA's independent application
policy and the ensuing discussion here address the issue of how the
three different kinds of assessments are interpreted only in the
context of protection of aquatic life and aquatic life uses and not in
the context of protection of human health or wildlife.
With the advent of different ways of assessing the health of
aquatic systems comes the possibility of conflicting results. To
address such conflicts, EPA developed the policy of independent
application. Independent application states that where different types
of monitoring data are available for assessment of whether a water body
is attaining aquatic life uses or for identifying the potential of
pollution sources to cause or contribute to non attainment of aquatic
life uses, any one assessment is sufficient to identify an existing or
potential impact/impairment, and no one assessment can be used to
override a finding of existing or potential impact or impairment based
on another assessment. The independent application policy takes into
account that each assessment provides unique insights into the
integrity and health of an aquatic system. In addition, each assessment
approach has differing strengths and limitations, and assesses
different stressors and their effects, or potential effects, on aquatic
systems. For example, while biological assessments can provide
information in determining the cumulative effect of past or current
impacts from multiple stressors, these assessments may be limited in
their ability to predict, and therefore prevent, impacts. While
chemical-specific assessments are useful to evaluate and predict
ecosystem impacts from single pollutants, chemical-specific methods are
unable to assess the combined interactions of pollutants (e.g.,
additivity). Similar to biological assessments, toxicity testing
provides a means of evaluating the aggregate toxic effects of
pollutants, and like chemical assessments, can also be used when
testing effluent to predict single chemical impacts. One of the
limitations of toxicity testing, however, is that the identification of
pollutants causing toxicity is not always possible or cost-effective.
Each of these three assessment approaches relies on different kinds of
water quality data, measures different endpoints and, in practice, will
be interpreted in the context of implementing a water quality
management program that includes assessment and pollution control.
EPA's policy on independent application is based on the premise that
any valid, representative data indicating an actual or projected water
quality impairment must not be ignored when determining the appropriate
action to be taken. Independent application recognizes the strengths
and limitations of all three assessment approaches.
The next three sections briefly describe three assessment
approaches (biological, toxicological and chemical) one could likely be
evaluating when using independent application. Those three sections are
then followed by two parallel discussions on different uses of water
quality data. One use relates to the NPDES permits program to determine
whether a permit must contain water quality-based chemical or toxicity
limits, and what those numeric limits should be. The other relates to
the use of such data to evaluate the quality, or condition, of waters
under the CWA section 305(b) and 303(d) programs. At the core of both
of these contexts is the question ``are the present applicable water
quality criteria complete and appropriate for the water body, and how
are we to measure attainment of the present or future criteria that
apply to any water body in question?'' Thus, in its most basic sense,
independent application remains a water quality standards question. Any
changes to or clarifications of the policy on independent application
must therefore be considered first under the rubric of water quality
standards and then in the separate contexts of permitting and water
quality evaluation which are based on water quality standards.
States and Tribes routinely determine whether water bodies are
attaining their designated uses and whether existing pollution controls
adequately protect those uses. Some States and Tribes have recommended
to EPA that it modify the independent application policy. Currently,
EPA's policy of independent application is the same for both NPDES
permitting and water quality assessment programs. However, EPA
recognizes that each of the programs has somewhat different data needs
and attributes. Therefore, today's notice separates the two distinct
uses of independent application to better focus the discussion.
a. Biological Assessments. Biological assessments are based on
quantifying differences between expected biological community
attributes such as structure, function and condition (known as a
reference condition) and the biological community attributes found at a
specific site being evaluated. The extent to which the community at the
site deviates from the reference conditions is indicative of the degree
of impairment at the specific site. The strength of biological
assessments is their ability to provide a direct measure of the health
of aquatic ecosystems. Biological assessments are also able to detect
non-chemical impacts (e.g., habitat loss, sedimentation, temperature
effects) in addition to chemical toxicity problems.
States and Tribes that use biological assessments, use them
primarily to evaluate the ecological condition of water bodies and to
determine whether a water body is healthy, threatened, or impaired
(i.e., aquatic life use attainment decisions). In some instances,
States and Tribes have used biological assessments to establish
monitoring requirements in an NPDES permit, but generally, most use
bioassessments to make non-regulatory, general, water resource
management decisions. Data from a biological assessment can be compared
to a gradient that shows the reference (expected) conditions without
impairment on one end and the worst situation on the other. States and
Tribes generally use the results to determine whether additional
measures are needed to protect the water segment, or determine how
close to attainment an impaired system is. Biological assessments can
also play a role in linking impairment to causative agents. This link
is often not definitive, but can be very useful in helping to identify
the causes and sources of many impairments. Some States and Tribes have
used indicator species or groups to distinguish effects of toxicity
from effects of organic enrichment. For example, one State documented
that a midgefly larvae is found to be predominant in areas contaminated
by electroplating or metal wastes. Although biological assessments
cannot be used to predict conditions in a mathematical modeling sense,
over time they can be used to indicate the direction of change, and the
degree of that change, in the condition at a particular site. This
information, where it is based on enough data using relatively
sensitive appropriate metrics, can be very valuable in deciding whether
the current condition is likely to be maintained under similar
conditions in the future, or whether there are early warning signs of
biological impacts giving reason to believe that additional regulatory
actions may be needed to prevent water quality standards impairment.
Regulatory actions that are a response to measured change in biological
condition will tend to be restorative more than preventative (i.e.,
[[Page 36796]]
once biological impact is measured, by definition, that impact was not
prevented). Although, slight changes that are not sufficient to render
a water in non-attainment of its aquatic life use, can provide early
warning of potentially more significant future changes. In contrast, as
noted above, regulatory actions based on impairment predicted, for
example via a chemical-specific modeling analysis, tend to be
preventative. To the extent that conditions in a water body do change
(e.g., flow), biological assessments do not reveal potential future
impacts under other exposure conditions (e.g., low-flow conditions).
Programmatically, there are concerns regarding quality assurance and
quality control for various biological assessment techniques since they
have yet to be promulgated, or standardized, in any EPA programs. This
is mainly due to the site-specific nature of biological assessments.
Implementation of biological criteria is also discussed in section (B)
of this notice.
b. Toxicological Assessments. Toxicological assessments are
conducted by exposing aquatic organisms to effluent or ambient water
samples or sediment samples in a laboratory and determining the effects
on the exposed organisms. Because toxicity assessments evaluate the
overall effects of the entire suite of constituents in a sample, they
are ideal for identifying interactions between chemicals that can alter
the expected effects of individual chemicals on exposed organisms.
Toxicity assessments also capture the toxic effects of chemical
compounds not commonly monitored for or for which chemical-specific
criteria are lacking. In addition, because it can be manipulated in the
laboratory, toxicity testing can predict the likelihood of ecological
impacts before they occur. This allows safeguards to be put into place
before an actual ecological impact occurs.
Toxicity assessments are usually limited by the variety of species
that can be cultured in the laboratory. While numerous test species can
be used to evaluate the toxicity of individual samples, typically only
two or three species are used for such tests. By comparison, eight
different families are required to develop chemical-specific criteria.
For some toxicants, the broader sensitivity range provided by testing
eight different families is particularly important, for example, where
the mode of toxicity action is specific (e.g., pesticides). Identifying
the cause of toxicity can, in some situations, be a difficult,
expensive, and lengthy process. Another consideration is that toxicity
testing does not detect habitat perturbations which can greatly limit a
water resources aquatic life use. Finally, toxicity assessments are
only valid for as long as all the sample testing conditions remain the
same. Ambient conditions affecting toxicity may change over time
necessitating additional testing.
c. Chemical Assessments. Chemical assessments measure individual
chemical constituents (e.g., copper, lead) or chemical conditions
(e.g., pH, temperature, hardness, organic content) in a medium.
Chemical assessments may be performed on effluent or ambient water
samples or sediment samples. Chemical analyses are usually simpler to
conduct and generally less expensive than toxicity assessments or
bioassessments, particularly if there are only a few chemicals of
concern, but the information from these tests may provide limited
insight into the ecological condition of the water body. If information
is available on pollutant persistence and degradation, modeling can be
used to predict pollutant fate and transport under a variety of
exposure scenarios. Further, chemical-specific assessments are ideal
for predicting the likelihood of ecological impacts where they may not
yet have occurred either because a proposed activity affecting water
quality has not been implemented or critical exposure conditions have
not yet been experienced by the aquatic community. For these reasons,
regulatory actions based on chemical-specific assessment can be
preventative as well as restorative.
Basing regulatory and management decisions on chemical assessment
of water quality is an important and proven aspect of water quality
assessment and protection. However, as an indirect measure of aquatic
health, one of the principal limitations to chemical assessments is
dependence upon chemical-specific benchmarks (such as chemical water
quality criteria) for determining whether water quality is suitable or
unsuitable for attaining and maintaining aquatic life uses. As noted
elsewhere in this notice, stressors other than specific chemicals in a
water body are often a significant or even predominant cause of
nonattainment of aquatic life uses. EPA's current thinking is that
complete reliance on chemical-specific assessments of water quality is
too narrow of a focus and fails to provide information on other
important ecosystem stressors. In addition, as noted elsewhere in this
notice, there are currently water quality criteria for the protection
of aquatic life for 31 chemicals. There are tens of thousands of
chemicals discharged into surface waters. (Note, however, that the
chemicals for which there are criteria tend to be the most frequently
discharged). Thus there is the added problem of too few criteria and
too many chemicals, making it inappropriate to rely exclusively on the
chemical-specific approach. Another substantial limitation of chemical-
specific benchmarks is that for a given site, the benchmarks that are
used, may not be the best that are available to reflect the level of
protection applicable at the site. For example, site-specific aquatic
life criteria are generally different (higher or lower) than the
national recommendations for the same chemical. And yet absent site-
specific criteria, the national recommendations are often used.
2. Independent Application and Water Quality Assessments
a. Independent Application. States and Tribes often collect or have
access to monitoring data that measure the concentration of specific
chemicals in an effluent or water body, the level of toxicity present
in ambient water or discharges to a water body and/or the biological
community composition within a water body. These data are then
interpreted by comparing them to reference conditions or criteria to
determine whether or not aquatic life uses are attained. EPA's 1991
policy on independent application was explicit about the use of
independent application in water quality programs: ``This policy,
therefore, states that appropriate action should be taken when any one
of the three types of assessment determines that the standard is not
attained. States and Tribes are encouraged to implement and integrate
all three approaches into their water quality programs and apply them
in combination or independently as site-specific conditions and
assessment objectives dictate.'' In implementing this policy, EPA
recommends that data from the three assessment approaches be applied
independently in water quality programs since each method provides
unique and distinct information on the characteristics of the water
body. In other words, EPA recommends that differences in assessment
results be resolved in one of two ways: either presume an adverse
impact when any one source of data indicates an adverse impact, or
reevaluate the complete data set and modify the applicable criteria to
account for the new site-specific information. Given EPA's mission to
protect the environment and absent definitive data to demonstrate that
an assessment is in error or otherwise biased, EPA presumes
[[Page 36797]]
where an assessment indicates impairment, that assessment is valid.
In the context of applying the independent application policy to
the assessment of water bodies, there are two distinct CWA provisions
to consider: (1) section 305(b), which requires States and Tribes to
report to EPA and EPA to report to Congress a description of the
quality of the Nation's waters; and (2) section 303(d), which relates
to identification of waters where technology-based limitations and
other required controls are not stringent enough to ensure that
applicable water quality standards will be attained and maintained.
With respect to the section 305(b) Report, the CWA broadly calls for
States and Tribes to assess water quality conditions in a biennial
report. EPA transmits these reports to Congress, together with an
analysis of the reports describing water quality conditions. Because
these are water quality assessment reports that States and Tribes
submit to EPA, and not specific regulatory decisions, there may be
sufficient flexibility in the interpretation of data to allow a more
integrated approach to evaluating limitations and inconsistencies in
the interpretation of data produced under various approaches. For
example, direct assessments of the condition of the waters (e.g.,
biological assessment) could be weighted more heavily than indirect
measurements (e.g., chemical and toxicity).
With respect to section 303(d), the CWA and EPA's implementing
regulations require States and Tribes to identify those waters for
which technology-based limitations and other required controls are not
stringent enough to achieve water quality standards applicable to such
waters. See 303(d)(1)(A), 40 CFR 130.7(b)(1). When identifying waters
pursuant to 303(d), the methods used to determine non-attainment of
standards for water quality reporting under 305(b) should also be used.
However, water bodies are eliminated from 303(d) list consideration if
technology-based controls or other required Federal, State, Tribal or
local requirements will result in the attainment of applicable water
quality standards. TMDLS developed to secure restoration of designated
uses are largely dependent upon chemical criteria and assessment to
define acceptable pollutant loadings.
The question arises as to whether States and Tribes have the
flexibility to exclude a water body from 305(b) reports and 303(d),
i.e., conclude that the designated use was protected, even in the face
of data indicating one or more excursions of the applicable chemical-
specific water quality criteria. EPA would like to consider possible
mechanisms under the existing CWA and the legal theories supporting
them to address these questions.
As with determining the need for regulatory controls (permit
limits), similar data evaluation issues face States, Tribes and EPA in
performing water body assessments for purposes of sections 303(d) and
305(b) of the CWA. With respect to such assessments, EPA's goals for
States and Tribes are twofold: (1) to encourage the use of chemical,
toxicological, physical and biological data in making water body
assessments; and, (2) to ensure that the data are interpreted and
reported in a consistent and scientifically defensible manner so that
documents such as the 305(b) report to Congress provide valid and
useful information on the status of the Nation's waters as a whole,
irrespective of State or Tribal boundaries.
EPA recognizes that there may be instances where these goals appear
to be in conflict. It is possible that as States and Tribes implement
biological assessment programs, they may identify new areas of impact
that were previously undetected using other assessment techniques and
that this may lead to a reluctance on the part of States and Tribes to
develop the expertise necessary to conduct biological assessments.
Although this tendency is contrary to the goals and objectives of the
CWA, the fact is that addressing new and previously unaddressed threats
to surface water quality places additional strain on already limited
State and Tribal resources. Some also feel that adherence to a strict
independent application policy for assessment purposes discourages the
use of more data than minimally needed to make an aquatic life use
assessment. In most cases, the minimal amount of data would be a
chemical grab sample for a few water quality characteristics such as
temperature, pH, BOD, or dissolved oxygen. Collecting minimal data for
assessment reporting is much easier and less resource intensive for
States and Tribes that are required to increase their reporting
coverage, and these States and Tribes would not have to deal with
differing interpretation of assessment results.
However, EPA believes that placement of waters on section 303(d)
and section 305(b) lists should be based on broad thorough assessment
data, not on limited and narrow data. The former will help ensure that
targeted water quality controls and management actions are appropriate
and will result in water quality standards attainment; the latter can
result in significant outlays of State and Tribal resources targeted on
waters where water quality problems are not well understood. EPA is
considering how best to obtain accurate, high-quality assessment data
and how to reconcile differences between assessments conducted using
different techniques in a manner that fosters consistency and remains
scientifically defensible.
b. Alternatives to Independent Application.
There is considerable sentiment among various stakeholder groups
that there is a need to better incorporate more comprehensive data,
particularly biological data, into the water quality assessment
framework described above and that doing so will facilitate collection
and use of more integrated and insightful water quality data. EPA
shares this view. Some have used the term ``weight-of-evidence'' to
describe an alternative to the present EPA policy of independent
application that could facilitate integration of chemical, physical,
toxicological and biological data into the assessment program. However,
EPA recognizes that individuals' views about the meaning of the term
``weight of evidence'' vary considerably and this variation should be
addressed. The term ``weight-of-evidence'' has been interpreted by some
to mean that one approach to assessment, e.g., biological, could
routinely be used to override conclusions drawn using another
assessment technique, e.g., chemical. EPA believes that approach is
hierarchical, not a weight-of-evidence approach. EPA's position is that
each approach, chemical, toxicological, physical and biological has
inherent strengths and limitations and that all valid water quality
assessment data generated under any of these approaches should be used
in assessing the health of aquatic ecosystems, in ways that adequately
take into account the strengths and limitations of each approach.
EPA's current thinking is that as forms of water quality assessment
data have become broader (chemical, physical, biological and
toxicological), and as the amount of such data increases, the water
quality standards and assessment programs need to facilitate continued
collection and use of such data, and that doing so will lead to more
thorough water quality assessments, more insightful water quality
criteria, and better descriptions of aquatic life designated uses. EPA
would not support an approach that could lead to collecting fewer and
narrower water quality data by States, Tribes and dischargers. On the
contrary,
[[Page 36798]]
EPA's current thinking is that to employ a weight-of-evidence approach,
a State or Tribe (or EPA) would need to have a comprehensive set of
water quality data to evaluate the chemical, physical, toxicological
and biological conditions in a water and to conduct ecological impact
assessment to determine the precise causes of impacts (chemical,
physical, biological, and toxicological) and how best to address them.
EPA's current thinking is that the most appropriate context for using a
weight-of-evidence approach would be in establishing criteria. In
addition, as discussed below, EPA is interested in evaluating the use
of a weight-of-evidence approach for assessment and reporting under
section 305(b) of the CWA. However, once the criteria are established
for a water body, the assessment for purposes of listing under section
303(d) of the CWA and permitting under NPDES, must be based on all
applicable water quality criteria.
EPA's 305(b) reporting guidelines interpret the independent
application policy to apply to aquatic life use assessments for State
305(b) reports, not just to permitting for protecting waters due to
reasonable potential to violate water quality standards. This policy
helps protect against dismissing valuable information when evaluating
aquatic life use attainment, particularly in detecting impairment. This
approach is most protective when there is limited data available and
when there is no documentation on the rigor of the assessment. EPA is
concerned that lack of information can provide false confidence about
the health of the nation's water bodies. However, EPA is now developing
a comprehensive approach for conducting aquatic life use assessments
which integrates chemical, toxicological, physical and biological data,
and includes consideration of the strengths and limitations of the
assessment methods and the data. This shift toward more integrated
assessments is reflected in EPA's most recent guidance to the States
and Tribes on conducting 305(b) assessments, particularly in
determining nonattainment (EPA's Guidelines for Preparation of the 1996
State Water Quality Assessments (305(b)) reports, EPA 841 B-95-001) and
is the primary focus of the Office of Water's Criteria and Standards
program Plan. The 1996 305(b) guidelines are consistent with the Policy
on Independent Application while incorporating a weight-of-evidence
approach in determining the degree of impairment (partial or
nonsupport). The 1996 guidelines do not allow for a finding of full
support, or attainment, of aquatic life use when there are differences
in assessment results. Under certain circumstances, however, the
guidelines allow for the possibility of a finding of partial support,
even where results of different assessments are not fully consistent.
Generally, in assessing severity of impairment, assessments based on
data with high levels of information, or rigor, should be weighted more
heavily than those based on data with low levels of information, and,
rigorous biological data should be weighted more heavily than other
data types. EPA recommends that the results of biological assessments,
especially those with high levels of information, be the basis for the
overall aquatic life use support (ALUS) determination if the data
indicate impairment. This is because rigorous biological data provide a
direct measure of the status of the aquatic biota and detect the
cumulative impact of multiple stressors on the aquatic community,
including new or previously undetected stressors.
Determining the level of information or rigor for each assessment
is a critical component of the 305(b) guidelines on making an ALUS
determination. The levels of information allow characterization of the
quality and the temporal and spatial coverage of the data States and
Tribes utilize to conduct their use assessments. Levels of information
are identified for assessments based on biological, physical, chemical
and toxicological data. For example, measures of the condition of the
aquatic community using indices incorporating multiple assemblages of
aquatic organisms based on a regional reference approach would rate
higher than a measure of a single organism or single metric or annual
fixed station monitoring for chemical contaminants. Likewise, three
years of bi-monthly fixed station monitoring for chemical contaminants
would rate higher than annual fixed station monitoring for the same
chemicals or a biological measure of a single organism or metric.
Understanding the breadth and robustness of the assessment methods used
in evaluating whether a water body is attaining its designated aquatic
life use is important information for EPA, the States, and the public.
In the future, EPA will be evaluating possible scenarios where a
finding of full support could be justified despite differences in
assessment results. For example, a finding of full support based on
rigorous biological data may be justified despite differences with
chemical specific assessment results depending on the magnitude and
frequency of the chemical exceedances and the applicability of the
chemical benchmark to the site. It will be important for EPA to
carefully evaluate such potential scenarios and to define the adequate
data requirements and level of rigor necessary to support a
determination of full support despite differences in assessment
results. Equally important, EPA will need to carefully consider the
ramifications of such determinations on other parts of its water
program.
Another permutation of the weight-of-evidence approach to aquatic
life use assessment is to establish a hierarchy in which the results of
one method could always override the other methods should there be
difference in assessment results. Most frequently, it has been argued
that biological assessments could always override chemical assessments
in determining whether the designated aquatic life uses are being
attained. Some prefer this approach because a rigorous biological
assessment provides a direct measure of existing ecosystem health and
have expressed concern that the policy of independent application
oversimplifies the relationship among different data sets used to
assess current water quality conditions. Proponents of this approach
contend that biological assessment is an integrated assessment that
incorporates the information that would be provided through either
chemical or toxicological assessments into a single, comprehensive
measure of aquatic ecosystem health. Some advocate the acceptance of
rigorous biological data as the ultimate arbiter of aquatic life use
attainment. They also suggest that, at least with respect to current
aquatic life condition assessments, chemical, toxicological, and
biological assessments are not independent; each measures the same
assessment endpoint, but from different stressors. These proponents say
that biological assessment is the only assessment approach available to
integrate and reflect current effects from chemical, toxicological,
physical, and nonpoint source stressors. Because of this they suggest
that rigorous data based on biological assessments and criteria should
automatically supersede data from other sources when determining
aquatic life use attainment. Some contend that if biological data
demonstrate that biological criteria are attained, then the water body
is attaining its designated use, even if other monitoring data such as
toxicological or chemical data demonstrate an excursion, or potential
for an excursion, above a water quality criterion.
Some also contend that rigorous biological assessments should be
used
[[Page 36799]]
to supersede assessments based on predicted impacts such as water
quality modeling and wasteload allocations in decision making for
aquatic life use assessments. One concern with this perspective is that
non-rigorous biological assessments could be used in such situations,
though EPA has 305(b) reporting guidance which suggest minimum quality
of biological assessments that could also be used for these situations.
In this guidance, EPA recommends using more than one assemblage (fish
and/or macro invertebrates/and or algae), several index values or
metrics (multiple metrics), an index period for sampling, and
ecoregional or other biogeographic regional calibration.
EPA agrees that rigorous biological assessment based on adequate
site-specific data is a direct assessment of aquatic ecosystem health,
unlike chemical and toxicity assessments. However, biological
assessments are less well suited for use in preventing water quality
impacts and will only reflect impacts once they have occurred. Though
this may be less of a concern in waters with a relatively constant
level of discharge where there has been ongoing biological assessment.
A second objective of water quality assessment under the CWA, beyond
assessing when the aquatic life use is impaired, is assessing when
stressors, if left unchecked, will cause impairment. As discussed
above, the chemical-specific approach is especially strong for use in
identifying and predicting impacts before they happen.
EPA is concerned that the use of a hierarchical approach may ignore
or undermine valuable information, whether that information is
biological, physical, chemical, or toxicological, and not trigger the
appropriate action to address the inconsistency (e.g., evaluation of
existing criteria and development of site-specific criteria).
Therefore, EPA does not support such an approach. EPA has a number of
concerns with any approach wherein data from certain assessment
techniques may be automatically superseded by those from others. A
primary concern is the failure of such a system to make use of all
valuable information. In all cases, criteria, whether chemical-
specific, toxicological, physical or biological, are derived with the
intent of identifying a threshold beyond which unacceptable impacts to
aquatic ecosystems are expected to occur. In most cases, it is expected
that when different assessment techniques (i.e., chemical and
biological) are used for determining attainment of aquatic life uses,
the techniques will yield similar results if all are done rigorously.
In addition, it is expected to be rare for chemical assessments to
indicate nonattainment where biological assessment indicate attainment;
analyses conducted by the State of Ohio confirm this. (See Yoder, C.,
``Answering Some Concerns about Biological Criteria Based on
Experiences in Ohio.''). However, it is also expected that in certain
cases, different assessment techniques will result in different
determinations of aquatic life use attainment due to the fact that each
technique evaluates aquatic life use attainment differently, and some
take into account safety factors for ensuring future attainment while
others focus on the current status of the condition. When different
assessment techniques that are intended to measure similar
environmental endpoints and yield comparable results fail to do so, it
may be an indication that assumptions underlying the criteria are not
valid for a particular site, or that the data were not rigorous.
While in some cases it may be appropriate to weigh one set of data
more heavily than another in making a use attainment determination, in
others it may be preferable to take advantage of such circumstances as
opportunities to validate and cross-check criteria, making adjustments
as indicated by the data. This could result, for example, in an
adjustment to a specific chemical criterion in a particular water if
rigorous biological assessment indicated that such an adjustment is
appropriate. Such information is also useful to EPA in improving
national criteria development methodologies.
Lack of comparability in assessments is also a concern for either a
weight-of-evidence or a hierarchical approach to aquatic life use
assessments. Therefore, it is important that there be a common
understanding between States, Tribes and EPA as to how conflicts in
data interpretation will be resolved in evaluating and reporting water
quality. Developing comparable methods to handle data conflicts will
make comparisons between States and Tribes more useful, such as in
305(b) reports. Without a consistent approach to resolving data
conflicts, assessments of water quality data at the national level
becomes problematic. EPA's policy of independent application is one way
of providing a consistent and defensible framework for data evaluation
in order to minimize this problem.
Request for Comments on integration of data in water quality
assessments
EPA is interested in comment on how chemical, physical,
toxicological, and biological assessments can be effectively
incorporated and implemented in State and Tribal water quality
standards programs to achieve the goals of the CWA.
EPA requests comments on the following questions:
1. How can conflicting interpretations of water quality assessment
data be reconciled in a scientifically defensible manner? Should each
kind of water quality information stand alone as a scientific measure
of current water quality conditions and ecosystem health?
Alternatively, are there situations where one type of data should be
given more weight than another in determining use attainment?
2. How should States and Tribes evaluate water quality information
generated using chemical, toxicological, physical, and biological
methods when determining use attainment status?
3. When interpretation of water quality data indicate inconsistent
results, what factors (i.e., data richness), if any, should EPA
consider relevant to determining ``appropriate actions''?
4. Should EPA explicitly address in the water quality standards
regulation the evaluation assessments using chemical, toxicological,
physical and biological assessment methods?
5. Should an approach be instituted where independent application
may be relaxed for water quality assessment strategies and decisions
when a State or Tribe has established a comprehensive monitoring and
assessment program including biological monitoring and assessment? What
guidelines should be used to evaluate a State or Tribal biological
monitoring and assessment program?
6. How should the policy of independent application address the
distinction between situations where adequate rigorous data are
available for each assessment technique and situations where available
data for one or more of the assessment techniques are limited in
quantity or quality? Specifically, should the policy be modified to
more explicitly encourage or require, where feasible, additional
monitoring, particularly where limited data are to be used as a basis
for regulatory action?
3. Independent Application and NPDES Permitting
a. Independent Application. Clean Water Act section 101(a) states
that ``[t]he objective of this Act is to restore and maintain the
chemical, physical, and biological integrity of the Nation's waters.''
In the context of implementing water quality-based pollution controls
under the NPDES program, EPA has maintained that independent
[[Page 36800]]
application of all forms of water quality assessment data (i.e.,
chemical, physical, toxicological and biological) is clearly consistent
with this objective. In addition to restoring impaired surface waters,
water quality-based pollution controls are often implemented to prevent
water quality standards impairment that projections indicate will occur
in the absence of the water quality-based controls. Thus, predictive
assessment tools are necessary and have proven effective in the NPDES
water quality-based program.
An important question in NPDES permitting that EPA's policy of
independent application was specifically developed to address is: how
should differences in interpretation of water quality data produced
using different water quality assessment techniques for aquatic life
uses be reconciled? Upon examination of this question, EPA determined
that differences in data interpretation do not necessarily equate to
contradictory results. Different assessment results may be
complementary since the different approaches can measure different
aspects of water quality. For aquatic life uses, all three data types
(chemical, toxicological, and biological) provide useful information
and should be used to protect designated uses. Because the different
types of assessments often focus on different aspects of aquatic
community health and each has different strengths and limitations, it
is possible that any one type of assessment may fail to detect
impairments, or potential impairments of the designated use. For that
reason, EPA's current interpretation of the CWA and its implementing
regulations is that all three types of data (chemical, toxicological,
and biological) should be used when evaluating the reasonable potential
for a discharge to cause or contribute to an excursion above a water
quality criterion and, if one approach indicates that water quality is,
or will be, impacted, the results from the other methods could not be
used to refute that finding. Under this approach, where ``reasonable
potential'' is found, the NPDES permitting authorities must take
appropriate ``actions;'' that is, implement water quality-based
effluent limits that are derived from and comply with the applicable
water quality criteria. These ``actions'' may also include additional
monitoring to determine whether a problem exists, or to derive site-
specific criteria if a particular criterion is found to be inaccurate
for a site. The policy on independent application is presented in
further detail in Chapter 1 of EPA's 1991 Technical Support Document
for Water Quality-based Toxics Control (TSD) and in chapter 1 of EPA's
Water Quality Standards Handbook--Second Edition, September 1994
(Handbook) (both documents cited above).
In the Great Lakes Guidance, EPA maintained its policy of
independent application with respect to determining the need for water
quality-based effluent limits, making it an explicit implementation
requirement in the Great Lakes States. The Guidance, in Appendix F,
Procedure 5, section F ``Other Applicable Conditions,'' states ``When
determining whether WQBELs are necessary, information from chemical-
specific, whole effluent toxicity and biological assessments shall be
considered independently.'' (40 CFR Part 132, Appendix F, Procedure 5,
Section F.3.).
In the permitting context, EPA's independent application policy
reflects language in sections 301(b)(1)(C) and 303 of the CWA and
permit regulations implementing these statutory provisions at 40 CFR
122.44(d). Pursuant to section 303 of the CWA, States and Tribes adopt
chemical-specific numeric criteria and toxicity criteria as part of
their water quality standards. Section 303(c)(2)(B) of the CWA further
requires States and Tribes to adopt, as part of their water quality
standards, numeric criteria for toxic pollutants for which EPA has
published guidance under section 304(a), and whose discharge or
presence in State or Tribal waters could reasonably be expected to
interfere with the designated uses adopted by the State or Tribe for
those waters. (As discussed elsewhere in this document, all States and
Tribes have narrative water quality criteria as well.)
Section 301(b)(1)(C) of the CWA requires effluent limitations in
NPDES permits that are ``necessary to meet water quality standards'' or
necessary to ``implement any applicable water quality standard.''
Consistent with this provision, EPA's permitting regulations at 40 CFR
122.44(d) require that effluent limits be imposed where the discharge
has the ``reasonable potential'' to cause or contribute to an excursion
above water quality criteria and specifically describe how those limits
are to be expressed (e.g., chemical-specific versus WET limits).
Therefore, once a numeric (or narrative) water quality criterion
becomes part of a State's or Tribe's water quality standards, and a
permitting authority determines that a discharge of a pollutant would
have a reasonable potential to cause or contribute to an excursion
above the applicable numeric or narrative criterion, the regulation
requires that a limit for that pollutant be established as necessary to
meet the water quality criterion. Although the CWA specifies that
permit limits must meet water quality standards, it is the permitting
regulations that specify the factors that must be considered when
determining whether or not there is reasonable potential to cause or
contribute to an excursion above a State or Tribal water quality
standard, and specifically describe how such limits are to be
expressed.
EPA regulations at 40 CFR 122.44(d)(1)(iii)-(v) describe the
conditions under which water quality-based effluent limits for specific
chemicals and for whole effluent toxicity are required in NPDES
permits. While these regulations do not specifically use the term
``independent application,'' the concept is expressly laid out. These
regulations require chemical-specific limits when the permitting
authority determines there is a reasonable potential for the discharge
to cause or contribute to the excursion above the chemical-specific
criterion. Likewise, the regulations require limits for whole effluent
toxicity if the permitting authority determines there is a reasonable
potential for the discharge to cause or contribute to the excursion
above the numeric criterion for toxicity or narrative criterion for
water quality. Except under limited circumstances (where the State or
Tribe lacks a chemical-specific criterion for a pollutant of concern),
these regulations do not allow a permitting authority to forgo one type
of limit, e.g. a chemical limit, where another type of data, e.g.,
toxicity, indicate no toxicity. Instead, the two types of data are
required to be considered independently.
The independent application policy provides a consistent and
coherent protocol for resolving conflicts in interpreting monitoring
data when determining ``reasonable potential.'' Where such conflicts
exist and cannot be reconciled, independent application directs States
and Tribes to presume that the data that indicate a current or
potential impact are valid and to take appropriate steps to prevent or
remediate the impact. The reconciliation phase allows a State or Tribe
to gather additional or more detailed data prior to taking regulatory
action. Data interpretation conflicts may be best addressed by
identifying the cause of the conflict and recalibrating the models and
criteria to better reflect the newly acquired site-specific
information. However, if the causes of the data interpretation
conflicts cannot be resolved, under independent application, the State
or Tribe must take
[[Page 36801]]
action based on the data indicating impairment or the reasonable
potential for impairment of the water body.
EPA believes this procedure for addressing conflicting
interpretations of monitoring data is appropriate for a number of
reasons. First, as stated earlier, each of the different assessment
techniques monitors aquatic ecosystem health from a slightly different
perspective. Consequently, it is entirely plausible that only one of
the assessment techniques would detect a real or potential impact.
Second, assuming that the data generated by the different techniques
are of comparable quality and relevance, an indication of a water
quality problem using any of the techniques is sufficient reason to
implement controls. That being the case, EPA believes the independent
application of water quality data in determining when water quality-
based effluent limits are necessary for individual dischargers is
consistent with the CWA.
Reconciliation of data interpretation conflicts allows flexible
evaluation of data. Once a permit application is received from a
discharger, States and Tribes frequently engage in discussions with the
discharger over the quality and representativeness of the data. This
period of data review and evaluation is also an ideal time for
addressing any data interpretation conflicts in order to ensure that
permitting decisions are defensible and the permit limits that are
imposed are necessary to protect designated uses. States and Tribes,
together with permittees, may obtain additional data to verify earlier
data or conduct timely studies to support the development of site-
specific criteria. Ultimately, these site-specific criteria may serve
as the basis for a permit limit, or a decision that it is not necessary
to limit a pollutant in a particular discharge. All of the actions
above are consistent with the independent application policy and the
CWA.
Critics of EPA's policy believe either that data from certain types
of water quality assessments have inherently greater value than data
obtained by other means or that, in a sense, data quality and
ecological significance should be averaged, such that if data obtained
from two different assessment methods agree and data from a third
disagree with the other two, the two could ``outweigh'' the one. In
either case, all of the available data would be considered together,
under the assumption that each assessment technique measures a similar
endpoint. Under such an approach to data evaluation, limits on effluent
toxicity would be appropriate and acceptable as surrogates for
chemical-specific limits. Similarly, biological assessment data that do
not indicate unacceptable levels of impact on the biological community
could serve as the basis for a decision not to include either chemical-
specific or effluent toxicity limits designed to support an aquatic
life use in a facility's discharge permit. Proponents of this view
argue that independent application forces them to take inappropriate
regulatory actions when faced with conflicting assessment data. EPA
does not agree in principle with this view.
b. Alternatives to Independent Application. States, Tribes,
municipalities, and dischargers have expressed concerns that the policy
of independent application results in more protection than is necessary
to attain and maintain aquatic life designated uses. Many express a
preference for an approach which invests data obtained using certain
assessment techniques with greater credibility than those obtained in
other ways. Such an approach, as discussed above, is sometimes referred
to as a weight-of-evidence approach. Under such an alternative
approach, assuming a high level of confidence in all the available
data, one form of data--usually it is argued biological data-- would be
the ultimate arbiter of whether water quality-based effluent limits are
needed in a discharger's permit. To determine, for example, whether a
water quality-based effluent limit is needed for a particular chemical
pollutant, the risk of adverse impact on the aquatic community would be
determined based on all of the available data relying more heavily on
high quality, thorough biological data and on the judgment of the
individual conducting the evaluation. Several States and members of the
regulated community have advanced this approach as preferable to EPA's
independent application policy, arguing that such flexibility to
exercise judgment is appropriate.
EPA's current thinking is that it should not promote an alternative
approach to making ``reasonable potential'' decisions that places
greater emphasis on biological data. Instead, EPA's current thinking is
that such an evaluation of water quality and ecosystem health to
determine the appropriate and applicable criteria against which
discharges will be evaluated is most appropriately done during the
setting of the applicable criteria for a water body. In that arena, it
may be feasible to use biological assessment as a basis for determining
the appropriate criteria for a given water body. However, once the
criteria are set, EPA believes that the current regulation requires
``reasonable potential'' evaluations against all the applicable
criteria, and that the policy of independent application in this
context is appropriate.
If biological data indicate that designated uses are being attained
in spite of projected or actual chemical-specific criteria exceedances,
then additional site-specific analysis should be done to ensure that
controls are developed that are necessary to adequately protect the
water body from use impairment. Site-specific approaches could include
mixing zone studies, more refined water quality modeling to support
wasteload allocation, or the development of site-specific criteria. In
any case, chemical-specific and toxicity criteria are proven and
necessary bases of water quality-based effluent limits. In ``reasonable
potential'' analysis, chemical-specific monitoring is usually focused
on pollutant concentrations in the effluent and the projected ambient
result of those concentrations being discharged. Thus, this type of
analysis commonly yields projected rather than measured water quality
impacts. Where biological impact is not detected using biological
assessment methods, it is possible that impairment that is projected
and plausible, may simply have not yet occurred. However, where
discharges to a stream have been relatively constant over time and
there has been ongoing biological assessment, this would be less of a
concern. EPA's view is that it would be inappropriate to ignore
projected impairment simply because the impairment has not yet been
observed in the environment.
An additional argument in favor of retaining the independent
application policy for ``reasonable potential'' determinations has to
do with the suitability of certain types of data and the unsuitability
of others for certain applications within the water pollution control
program. For example, biological data are not amenable in the same way
as chemical-specific data for use in waste load allocations, load
allocations, total maximum daily load calculations or antidegradation
reviews. An approach that would allow biological data to negate a
finding of ``reasonable potential'' would suggest possible site-
specific inadequacies of particular criteria without providing the
information needed to determine definitively whether or not the
criteria are appropriate or what any alternative criteria should be. As
a consequence, a void would be created in the implementation of State
or Tribal water quality standards which would render them unable to
perform all of their
[[Page 36802]]
intended functions. Proponents of independent application contend that
instead of discarding data and invalidating criteria where conflicting
interpretations exist, an effort should be made to determine why the
interpretations conflict and to refine the applicable criteria to
better reflect the conditions found at the site. Taking this step would
ensure that, over time, a full suite of appropriate criteria would be
developed for every site and that all appropriate and necessary
pollution controls are implemented. In addition, such an approach is
consistent with the CWA. Some States and Tribes may be concerned,
however, that revising water quality standards, especially where such
revision is to deal with a single permitting decision, may be so
resource intensive that it is not a realistic option.
As discussed above, if numeric water quality criteria exist and are
applicable to a water body, permits for dischargers to the water body
must ensure that those criteria are met under section 301(b)(1)(C) and
the implementing regulations at 40 CFR 122.44(d). On occasion, States,
Tribes and dischargers have asserted that biological and toxicity data
from specific waters conflict with chemical data. EPA's current
thinking is that instances of clear disagreement between biological and
toxicity data and chemical data are infrequent. Based on this belief,
EPA would not support a radical shift away from chemical criteria and
limits or toxicity criteria and limits. Those tools are simply too
important as proven tools for assessing potential impacts to surface
waters and improving water quality. EPA's current thinking also
suggests that it is important for there to be flexibility to resolve
instances of disagreement between different forms of data and that
perhaps mechanisms for such flexibility can be clarified or improved.
EPA's current thinking is that through collection of broader and more
thorough water quality data, EPA, States and Tribes will be able to
develop more complete profiles of water body conditions and stressors
and that through such evaluation the ``necessary actions'' (e.g., water
quality-based effluent limits for one or more pollutants, listing of
the water body as not attaining its aquatic life designated use, or
best management practices to address nonpoint sources of pollution) to
improve water quality in a given water will become more obvious.
Disagreement between biological, toxicity and chemical data for the
same water is cited by some States and dischargers as a potential
situation in which independent application would force unnecessary and
burdensome requirements on dischargers. Those opposed to independent
application of criteria would like to see States and Tribes given
greater latitude to determine when limits based on a given criterion
are necessary. They suggest that this could be achieved if States and
Tribes were to include, in the chemical-specific criteria or toxicity
criteria portions of their water quality standards, statements
explaining circumstances under which the otherwise applicable criteria
would not apply at a particular site or would have to undergo some
review and revision, while assuring the designated use of the water
body would be maintained. Such circumstances could include where the
form of the pollutant in the effluent or receiving water is not the
form addressed by the chemical criterion in the State or Tribe's
standards; or, where a substantial amount of biological and or toxicity
data indicate that discharges of the pollutant at levels that would
exceed the chemical criteria are not causing the aquatic life use in a
particular water body or segment of the water to be impaired. If these
conditions could be met, permitting authorities would have the
flexibility to determine that a numeric water quality-based effluent
limit for the pollutant in question is not required, or that an
alternate limit should apply. This type of flexibility, to rely on
biological evaluations in the criteria setting phase, where data are
sufficient to support such flexibility, could be a strong incentive for
States and Tribes to develop stronger biological criteria and
assessment programs including monitoring reference areas and complete
chemical and toxicity monitoring programs, including site-specific data
on most sensitive species to chemical(s) for which flexibility is being
sought. EPA approval of water quality standards implementing such an
option requires acceptance of an interpretation that sections
301(b)(1)(C) and 303(c)(2)(B) of the CWA allow States and Tribes to
identify, within their water quality standards, conditions or
circumstances which would render specific numeric criteria not
applicable to certain waters in specific instances, or alternatively in
need of refinement.
EPA has significant technical questions about how such an option
could be implemented within the context of a State's or Tribe's water
quality standards. EPA is especially interested in detailed technical
comments describing how such an option would be included in a State's
or Tribe's water quality standards, how such an option would ensure
protection of designated uses in water bodies where criteria are deemed
not applicable. In addition, EPA is soliciting comment on specific
procedures that could be used by a State or Tribe to arrive at a
decision that a criterion is not applicable at a specific site. In
particular, EPA is interested in technical evaluations of what types of
data would be necessary to support such a decision, the quantity and
quality of the data and how the data would be evaluated. Finally, EPA
seeks detailed technical comments indicating how other elements of the
water quality standards program would function in situations where
chemical or toxicological water quality criteria were adjusted based on
biological assessments. For example, if a State or Tribe were to employ
the option discussed above, it is not apparent how critical water
quality program elements such as determining the need for permit limits
or whether or not a new discharge could be allowed to a stream segment
could occur absent chemical-specific or toxicity-based criteria
applicable to the water body. To be workable, this option may need to
be paired with a scientifically defensible mechanism for making
decisions about activities such as permit limits and load increases.
Since chemical criteria and chemical-specific interpretations of
narrative criteria currently are the principal benchmark used for these
functions, would pursuing the option discussed above be workable, or
would it introduce a level of complexity into State and Tribal water
quality standards that could result in slowed or suspended water
pollution control programs, and expose aquatic ecosystems to greater
risk because of the lack of an identified threshold of impact?
EPA's current thinking is that significant flexibility already
exists within the current regulatory framework to account for available
biological and toxicity data. For example, numeric criteria, once
adopted, may be modified to better reflect conditions at a specific
site. Bioassessment and toxicity data can play a valuable role in
identifying sites where conditions differ sufficiently from those
assumed in the calculation of the national or State or Tribe-wide
criteria to warrant site-specific modification of the criteria.
Bioassessment and toxicity data can also provide useful information in
identifying instances where a given constituent in an effluent is
toxicologically distinct from a similar substance for which a criterion
is available, indicating the need for a separate criterion for the
constituent in
[[Page 36803]]
question. Establishing site-specific criteria would provide relief
similar to that contemplated in the option proposed above.
Lastly, public participation is a basic tenet of the water quality
standards development process. Public participation is also sought in
the context of issuing NPDES permits. During standards development,
public input is sought to assist the regulatory agency in identifying
the appropriate water quality goals for the waters under the
jurisdiction of a State or Tribe. During NPDES permit issuance, public
input is again sought to verify that the permit proposed to be issued
is consistent with the water quality goals. Some assert that these two
public participation steps seek input on different questions and are
not interchangeable. Does the weight-of-evidence option discussed above
reduce the opportunity for meaningful public participation in the
standards setting process by making it more difficult for the public to
determine which water quality criteria will apply to which water
bodies, and, as a result, what the water quality goals for an
individual water body are? EPA is considering how a weight-of-evidence
approach might be implemented in a manner that does not restrict the
opportunities for meaningful public participation in the water quality
goal setting process.
Request for Comments on Independent Application
EPA requests comment on the following questions:
1. What is the rationale for modifying the independent application
policy as it pertains to NPDES permitting? Under what circumstances
could it be justified?
2. If there are circumstances where an approach other than
independent application is acceptable, should any one type of water
quality data receive greater weight and why?
3. How should States and Tribes evaluate effluent data generated
using chemical, toxicity and biological methods in determining
reasonable potential to cause or contribute to an impairment?
4. Would checks or oversight mechanisms be necessary to ensure that
where decisions about reasonable potential are based on chemical,
toxicity and biological methods, such decisions are made with
integrity? For example, EPA or public oversight?
5. Are there any cases which indicate that either chemical-
specific, whole effluent toxicity or biological approaches do not
legitimately represent some aspect of use attainment?
6. Should EPA explicitly incorporate into the water quality
standards regulation the independent application policy?
7. Should independent application be addressed the same or
differently for permitting than for assessment and use attainment
decisions under 305(b) reporting and 303(d) listing?
8. If EPA were to separate the use of independent application in
determining the use attainment status of a water body from the use of
independent application when determining reasonable potential for an
effluent, what approach, independent application, weight-of-evidence,
or hierarchical, should be used for use attainment decisions? NPDES
permitting? What would the implications be if the programs used two
different policies?
9. Would a policy allowing numeric criteria to not apply to all
waters where supported by scientifically defensible data be workable?
Would it unnecessarily complicate the regulatory program, for example
by delaying the issuance of permits? Are existing mechanisms of
criteria setting and permit issuance sufficiently flexible?
IV. Summary and Potential Program and Regulation Changes
EPA believes that the water quality standards program and decisions
it yields will continue to be the focus of growing pressure and
scrutiny as solutions to remaining surface water quality problems in
this country are found to be increasingly elusive, difficult, and/or
expensive. The task set forth by the Clean Water Act is to improve
water quality even where it is difficult to do so. To accomplish this
task, EPA envisions a national water quality standards program in
which: the best possible information on whether designated uses are
being attained and how to attain and maintain them is available and
used; water quality criteria are selected from a wide-ranging menu of
scientifically sound criteria and tailored to each watershed; and
national norms of consistency and flexibility in State and Tribal water
quality standards are clear.
With this vision in mind, EPA, through this ANPRM, begins a review
of the water quality standards regulation in a public forum in an
attempt to identify possible amendments to the regulation and new
guidance or policy that may be needed to address three distinct
objectives: (1) eliminate any barriers to, and otherwise enhance State
and Tribal implementation of, watershed-based water quality planning
and management; (2) facilitate use of new, more integrated water
quality assessment and criteria science in water quality standards
programs, and; (3) improve the regulation so that it can be implemented
more efficiently and effectively (including cost-effectively).
The preceding pages of this ANPRM outline current regulatory
provisions, accompanying guidance and policy, and current practices in
the core areas of the water quality standards program. Each section of
the ANPRM identifies issues that have been raised to EPA that come out
of the collective experiences of States, Tribes, cities, industry and
environmental advocates, as well as EPA's experience. The issue
discussions are followed by specific questions that are intended to
elicit focused comments. It is important for commenters to focus on
these specific questions as a vehicle for developing comments. It is
equally important for commenters to develop ideas that address the
three objectives above in a more general sense and to identify the five
to seven highest priority issues the commenter believes EPA should
address in a follow-on regulatory proposal. EPA welcomes ideas on how
the water quality standards regulation, policy and or guidance can be
revised to facilitate water quality management on a watershed basis. In
requesting comment on eliminating barriers to and facilitating
implementation of watershed-based water quality planning and
management, EPA directs commenters' attention primarily to the sections
on designated uses, criteria, antidegradation, mixing zones and
independent application. In requesting comment on how to facilitate use
of new, more integrated water quality assessment and criteria science
in water quality standards, EPA directs commenters' attention primarily
to the sections on biological criteria, and independent application. In
requesting comment on how to improve the efficiency and effectiveness
(including cost-effectiveness) of the water quality standards program,
all sections of the ANPRM are relevant for review.
EPA seeks a water quality standards program that protects the
nation's waters as envisioned in the CWA, that establishes requirements
that are necessary to attain and maintain healthy and sustainable
ecosystems, and that is flexible enough for States and Tribes to
protect water quality and at the same time avoid costly requirements
that have little or no environmental benefit.
Below is a brief summary outline of the potential changes to the
water quality standards program and
[[Page 36804]]
regulation that are discussed and considered in this ANPRM. The list of
potential changes includes the potential changes to the program and
regulation on which EPA is specifically requesting comment. Each area
of potential change is discussed in detail in the specified section of
the ANPRM. It is possible that EPA will ultimately propose some of the
changes outlined below. It is also possible that EPA will conclude
based on the public comments it receives that some or all of the issues
presented in the ANPRM can be best addressed through non-regulatory
mechanisms such as guidance or policy.
A. Uses
1. Refinement of use designations to achieve increased specificity
in aquatic life and recreation uses being protected.
2. Minimum elements of a use attainability analysis (UAA).
3. When is UAA required/not required?
a. UAAs whenever an aquatic life use is designated (beyond
fishable/swimmable) to see if the use reflects the highest potential
for the water body.
b. Periodic review of marginal or limited aquatic life use
designations.
c. When is a use considered attainable?
d. Conditions under which refinements in designated uses may be
considered actions not requiring analysis to support use removal and
alternatively the conditions under which such action is considered a
use removal requiring justification under Sec. 131.10(g).
e. Circumstances under which UAA is required and circumstances
under which UAA must be reviewed.
4. Removal of designated uses.
a. Minimum aquatic life uses for all waters, because even degraded
water bodies support some form of aquatic life.
b. Evaluate use removal provision at Sec. 131.1(10)(g) allowing
removal of a use due to the existence/operation of a dam.
c. Clarify whether the physical factors reason for removing a use
includes removal of a recreational use due to poor physical access to
the water. Alternatively, the removal of a use for physical factors
could be limited to aquatic life uses only.
d. Clarify in Sec. 131.10 that at least one of the six use removal
criteria must be met to remove any use, not just aquatic life and
recreation uses.
5. Alternatives to use downgrade such as variances, temporary
standards and ambient-based criteria.
a. Recognize site-specific criteria set to natural background
levels as a permissible alternative to use downgrade.
b. Recognize site-specific criteria set to irreversible
anthropogenic background levels as a permissible alternative to use
downgrade.
B. Criteria
1. Ambient Water Quality criteria for Aquatic Life Protection.
a. Examination and possible interim revisions to EPA
recommendations on the duration and frequency of criteria excursions to
account for organism response model and population response model.
2. Site-specific criteria and procedures.
a. Specify that States and Tribes must have regulatory procedures
for establishing site-specific criteria.
b. Minimum requirements for development of site-specific criteria.
3. Narrative criteria and interpretation procedures.
a. Identify additional methods for implementation of narrative
criteria.
b. Clarify that States and Tribes are required to adopt narrative
criteria for all waters. (all States already have).
4. Codification of CWA requirement to adopt numeric toxics
criteria.
a. Define ``reasonable expectation'' under 303(c)(2)(B). (``States
and Tribes may adopt numeric chemical-specific criteria for those
stream segments where the State or Tribe determines that the priority
toxic pollutants for which EPA has issued CWA section 304(a) criteria
guidance are present and can reasonably be expected to interfere with
designated uses.'' emphasis added)
5. Chemical criteria beyond priority pollutants.
a. Develop and recommend or require criteria for certain non-
priority pollutants.
6. Numeric values in the absence of criteria or data sufficient for
criteria.
a. States and Tribes develop method for derivation of alternative
values where minimum data requirements for criteria not satisfied.
Specific EPA derivation procedure or guidelines.
7. Require or recommend that State and Tribes adopt numeric
toxicity criteria.
8. Sediment quality criteria.
a. Require or recommend that States and Tribes adopt sediment
criteria (narrative or numeric).
b. Specify in regulation that States and Tribes have the
flexibility to adopt sediment quality criteria.
9. Biological criteria.
a. Require or recommend that States and Tribes adopt biological
criteria (narrative or numeric).
b. Specify in regulation that States and Tribes have the
flexibility to adopt biological criteria.
c. Specify linkage between biological criteria and stressor
identification.
10. Wildlife Criteria.
a. Recognize in regulatory text that wildlife criteria are valid
forms of water quality criteria.
b. Recognize in regulatory text that wildlife criteria endpoints
other than bioaccumulation endpoints are valid bases for wildlife
criteria.
11. Physical criteria: Existing and potential future role of.
a. Identify physical criteria such as habitat (including clean
sediment) and hydrologic balance criteria in 40 CFR 131 as valid forms
of criteria that States and Tribes can adopt in their water quality
standards.
12. Human Health Criteria.
a. Higher fish consumption assumptions for site-specific or
regional situations when subpopulations that are highly exposed have
been identified.
b. Clarification of the use of MCLs and MCLGs in State and Tribal
water quality standards.
C. Antidegradation
1. Minimum elements of State and Tribal antidegradation
implementation procedures.
a. Revise regulation to include the minimum elements of a State and
Tribal antidegradation implementation method.
b. Revise the regulation to explicitly say that State and Tribal
antidegradation implementation procedures (in addition to just the
policy) must be submitted in triennial review package and are
reviewable by EPA.
2. Tier 1 protection (protection of existing uses).
a. Define or clarify what constitutes loss of an existing in-stream
water use.
b. Specify that a clear approach to maintaining and protecting
existing uses that may not be adequately protected by strict
application of water quality criteria is a required element of an
antidegradation implementation procedure.
3. Waters covered by tier 2 level protection.
a. Clarify waters subject to tier 2 level protection.
b. Clarify tier 2 provision requiring all cost effective and
reasonable best management practices for nonpoint sources prior to
allowing a lowering of water quality.
c. Clarify that States and Tribes are to consider the 303(d)
listing status of a water body, and the information supporting that
status, when determining whether a proposed activity that is expected
to degrade water quality in that water body can be authorized under
tier 2 of the State's or Tribe's antidegradation provisions.
[[Page 36805]]
4. Outstanding national resource water (ONRW) classification, level
of protection, and public role in nominating.
a. Public nomination of ONRWs.
b. Level of protection afforded to ONRWs.
5. Creation of Antidegradation tier 2.5.
a. Revise the regulation to explicitly recognize tier 2.5
protection.
D. Mixing Zone Policy and Implementation Procedures
1. Specify that, to use mixing zones, States and Tribes must
indicate in their water quality standards whether they allow mixing
zones, conditions under which mixing zones are allowed, minimum
requirements for mixing zones.
2. Procedures and decision criteria used in addressing complete and
incomplete mixing.
3. Site-specific technical justification for rapid and complete mix
assumption.
4. State and Tribe policies and procedures to address rate of
mixing.
5. Clarify in regulation that narrative criteria apply in mixing
zones.
6. Restrict Mixing zones for bioaccumulative chemicals of concern.
E. Applicability of Water Quality Standards to Wetlands
1. Clarify in 40 CFR Part 131 that wetlands with interstate
commerce connection are waters of the U.S. requiring water quality
standards.
F. Evaluation of EPA Policy of Independent Application (IA)
1. Increase use of chemical, toxicological, physical and biological
data in making water body assessments in a consistent and
scientifically defensible manner.
2. Specify how, and the circumstances under which, different forms
of assessments (chemical, toxicological, physical and biological) can
be used together to determine:
a. When a designated aquatic life use is or is not attained,
b. The type and value of criteria that should apply to a water, and
c. When water quality-based effluent limits are required in a
permit.
3. Specify the adequate data base and level of rigor necessary in
biological assessments to support a determination of full use support
despite differences in assessment results.
In addition to the potential program and regulation changes
outlined above, EPA is also requesting comment on the costs and
benefits and potential reporting and record keeping requirements that
might be associated with these changes. These issues are discussed more
fully in the next section.
V. Regulatory Assessment Requirements
A. Executive Order (E.O.) 12866, Regulatory Planning and Review
Under Executive Order 12866, [58 Federal Register 51,735 (October
4, 1993)] the Agency must determine whether the regulatory action is
``significant'' and therefore subject to Office of Management and
Budget (OMB) review and the requirements of the Executive Order. The
Order defines ``significant regulatory action'' as one that is likely
to result in a rule that may:
(1) Have an annual effect on the economy of $100 million or more or
adversely affect in a material way the economy, a sector of the
economy, productivity, competition, jobs, the environment, public
health or safety, or State, local, or tribal governments or
communities;
(2) Create a serious inconsistency or otherwise interfere with an
action taken or planned by another agency;
(3) Materially alter the budgetary impact of entitlements, grants,
user fees, or loan programs or the rights and obligations of recipients
thereof; or
(4) Raise novel legal or policy issues arising out of legal
mandates, the President's priorities, or the principles set forth in
the Executive Order.
While this advance notice of proposed rule making establishes no
regulatory requirements it could ultimately result in a rule that would
satisfy one or more of the above criteria. It has therefore been
determined that this action is a ``significant regulatory action''
under the terms of Executive Order (E.O.) 12866. As such this action
was submitted to OMB for review. Changes made in response to OMB
suggestions or recommendations have been documented in the public
record.
Under the terms of E.O. 12866, EPA is to prepare for any
significant regulatory action an assessment of its potential costs and
benefits. If that action satisfies the first of the criteria listed
above, this assessment must include, to the extent feasible, a
quantification of these costs and benefits, the underlying analyses
supporting such quantification, and an assessment of the costs and
benefits of reasonably feasible alternatives to the planned regulation.
Because the purpose of this notice is to initiate a structured national
debate on a broad set of issues rather than to propose specific
regulatory changes, it is not feasible to quantify the costs and
benefits of any resulting regulations at this time. The Agency is
aware, however, that this notice could lead to a regulatory action for
which the preparation of a quantitative assessment of costs and
benefits would be appropriate. The Agency is thus requesting comment on
the costs and benefits of any of the possible regulatory changes
discussed in this notice, as well as on appropriate methodologies for
assessing them. The Agency would be particularly interested to hear
from States and Tribes that may already have experience implementing
some of the measures discussed in this Notice and may already have
prepared analyses of the costs and/or benefits of such measures. Other
members of the public are also encouraged to submit any data they may
have on the costs and benefits of specific measures (e.g., conducting
biological assessments).
B. The Regulatory Flexibility Act (RFA) as Amended by the Small
Business Regulatory Enforcement Fairness Act (SBREFA) of 1996
Under the RFA, (5 U.S.C. 601 et seq.), as amended by SBREFA, for
proposed rules, EPA generally is required to conduct an initial
regulatory flexibility analysis (IRFA) describing the impact of the
regulatory action on small entities as part of rulemaking. However,
under section 605(b) of the RFA, if the Administrator for the Agency
certifies that the rule will not have a significant economic impact on
a substantial number of small entities, EPA is not required to prepare
an IRFA. The requirement applies to proposed rules only and as this
notice is an ANPRM, these requirements do not apply to this notice.
C. Paperwork Reduction Act
Under the implementing regulations for the Paperwork Reduction Act,
an agency is required to certify that any agency-sponsored collection
of information from the public is necessary for the proper performance
of its functions, has practical utility, is not unnecessarily
duplicative of information otherwise reasonably accessible to the
agency, and reduces to the extent practicable and appropriate the
burden on those required to provide the information (5 CFR 1320.9). Any
proposed collection of information must be submitted, along with this
certification, to the Office of Management and Budget for approval
before it goes into effect. Most of the potential regulatory changes
discussed in this Notice could entail new reporting and record keeping
requirements for States and Tribes and/or members of the regulated
public. EPA
[[Page 36806]]
is interested in comments on any and all aspects of these potential
paperwork requirements, and in particular on how they should be
structured to fulfill the requirements that they have practical
utility, are not unnecessarily duplicative of other available
information, and are the least burdensome necessary to satisfy the
purposes of the Water Quality Standards Program.
Dated: June 25, 1998.
Robert Perciasepe,
Assistant Administrator for Water.
[FR Doc. 98-17513 Filed 7-6-98; 8:45 am]
BILLING CODE 6560-50-P