[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]]


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

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.

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

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:

------------------------------------------------------------------------
                                             Examples of potentially    
                Category                        affected entities       
------------------------------------------------------------------------
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.            
------------------------------------------------------------------------

    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

[[Page 36744]]

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

[[Page 36745]]

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

[[Page 36746]]

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

[[Page 36762]]

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

[[Page 36782]]

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