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 § 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 bodyspecific 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 timelimited 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 36759 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 § 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 § 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 shortterm variances to individual dischargers based on any of the six factors for removing a designated use as listed at § 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 sourcespecific 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 36760 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 costeffective 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 § 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 shorterterm 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; 36761 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules   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 sitespecific 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 sitespecific 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 preexisting criteria and the ambient based criteria). EPA is interested in hearing comments regarding these ambientbased 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 § 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 crossreferencing 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 36762 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 § 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 chemicalspecific 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 sitespecific 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 36763 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 sitespecific 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 scientificallyderived 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 shortterm 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 36764 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 inten 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 oneday 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 sitespecific 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 sitespecific 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 sitespecific 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? 36765 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 ecosystemspecific 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 36766 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 subsection ( 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 reservationwide 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 36767 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 nonpriority 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 nonpriority 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 36768 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 36769 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 nonionic organics concluded that: `` these criteria not be used as stand alone, passfail 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 36770 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 biologicallybased 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. 36771 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 36772 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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 36773 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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. Humancaused 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 finegrained 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 36774 Federal Register / Vol. 63, No. 129 / Tuesday, July 7, 1998 / Proposed Rules 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?