Federal promulgation of State water quality standards should be a course of last resort. It is symptomatic of something awry with the basic statutory scheme. Yet, when it is necessary to exercise this authority, as the evidence suggests is this case, there should be no undue impediments to its use. Section 303( c)( 4) is replete with deadlines and Congressional directives for the Administrator to act " promptly" in these cases. The statute indicates that the Administrator of EPA, is to "* * * promptly prepare and publish proposed regulations setting forth a revised or new water quality standard * * *" and "* * * shall promulgate any revised or new standard * * * not later than 90 days after he published such proposed standards, unless prior to such promulgation, such State has adopted a revised or new standard which the Administrator determines to be in accordance with the Act." EPA intends to make every effort to meet the 90 day schedule. The adoption of section 303( c)( 2)( B) reinforced this emphasis on expeditious actions. EPA has demonstrated extensive deference to State primacy and a willingness to provide broad flexibility in their adoption of State standards for toxics. However, to fulfill its statutory obligation requires that EPA's deference and flexibility cannot be unlimited.

For the reasons just discussed, EPA does not believe it is necessary to support the criteria proposed today on a pollutant specific, State by State, waterbody by waterbody basis. Nonetheless, over the course of the past several years in working with and assisting the States, the Agency has reviewed the readily available data on the discharge and presence of priority toxic pollutants. While this data is not necessarily comprehensive, it constitutes a substantial record to support a prima facie case for the need for numeric criteria for most priority toxic pollutants with section 304( a) criteria guidance in most States. In the absence of final State actions to adopt criteria pursuant to either Option 2 or 3 which meet the requirements for EPA approval, this evidence strongly supports EPA's decision to propose, pursuant to Section 303( c)( 4)( B), criteria for all priority toxic pollutants not fully addressed by State criteria. The EPA data supporting this assertion is discussed more fully in the next section.

2. Approach for Developing Today's Proposed Rulemaking The proposed State specific requirements in Sec. 131.36( d) were developed using one of two approaches. In the formal review of the adopted standards for certain States, EPA has determined that specific numeric toxics criteria are lacking. For some, criteria were omitted from the State standards, even though in EPA's judgment, the pollutants can reasonably be expected to interfere with designated uses. In these cases where EPA has specifically identified deficiencies in a State submission, today's proposed rule would establish Federal criteria for that limited number of priority toxic pollutants necessary to correct the deficiency.

For the balance of the States, EPA proposes to apply, to all appropriate State waters, the section 304( a) criteria for all priority toxic pollutants which are not the subject of approved State criteria. EPA also proposes to promulgate Federal criteria for priority toxic pollutants where any previously approved State criteria do not reflect current science contained in revised criteria documents and other guidance sufficient to fully protect all designated uses or human health exposure pathways, where such previously approved State criteria do not protect against both acute and chronic aquatic life effects, or where such previously approved State criteria are not applicable to all appropriate State designated uses. EPA encourages public comments regarding any data which demonstrate that specific priority pollutants or water bodies may not require Federal criteria to protect State designated uses.

Absent a State by State pollutant specific analysis to narrow the list, existing data sources strongly support a comprehensive rulemaking approach. Information in the rulemaking record from a number of sources indicates the discharge, potential discharge or presence of virtually all priority toxic pollutants in all States. The data available to EPA has been assembled into a " strawman" analysis designed to identify priority toxic pollutants that potentially require the adoption of numeric criteria. Information on pollutants discharged or present was identified by accessing various national data sources:  Final section 304( 1) short lists identifying toxic pollutants likely to impair designated uses;  Water column, fish tissue and sediment observations in the Storage Retrieval ( STORET) data base ( i. e., where the pollutant was detected);  The National Pollutant Discharge Elimination System's ( NPDES) Permit Compliance System data base to identify those pollutants limited in direct dischargers' permits;  Pollutants included on Form 2( c) permit applications which have been submitted by wastewater dischargers;  Information on discharges to surface waters or POTWs from the Toxics Release Inventory required by the Emergency Planning and Community Right To Know Act of 1986 ( title III, Pub. L. 99 499);  Pollutants predicted to be in the effluent of NPDES dischargers based on industry specific analyses conducted for the Clean Water Act effluent guideline program.

The extent of this data supports a conclusion that promulgation of Federal criteria for all priority toxic pollutants with section 304( a) criteria guidance documents is appropriate for those States that have not completed their standards adoption process. This conclusion is supported by several other factors.

First, many of the available data sources have limitations which argue against relying on them solely to identify all needed water quality criteria. For example, the section 304( l) short lists only identified water bodies where uses were impaired by point source discharges; State long lists did not generally identify pollutants causing use impairment by nonpoint sources. Other available data sources ( i. e., NPDES permit limits) have a similar narrow scope because of their particular purposes. Even the value of those data bases designed to identify ambient water problems is restricted by the availability of monitoring data.

In many States, the quantity, spatial and temporal distribution, and pollutant coverage of monitoring data is severely limited. For example, the most recent Water Quality Inventory Report to Congress included an evaluation of use attainment for only one third of all river miles and less than one half of lake acres. Even for those waters where use attainment status was reported, many assessments were based on data which did not include the chemical specific information necessary to identify the priority toxic pollutants which pose a threat to designated uses. After evaluating this data, EPA concluded that it most likely understates the adverse presence or discharge of priority toxic pollutants.

Further evidence justifying a broad promulgation rulemaking can be found in the State actions to date in their standards adoption process. While many have not come to completion, the initial steps have led many States to develop or propose rulemaking packages with extensive pollutant coverage. The nature of these preliminary State determinations argues for a Federal promulgation of all section 304( a) criteria pollutants to ensure adequate public health and environmental protection against priority toxic pollutant insults.

EPA's strawman analysis for each State is described in greater detail in part III of appendix 1 and the complete record is available for public review. The detailed assumptions and " rules" followed by EPA in writing the proposed Sec. 131.36( d) requirements for all jurisdictions are listed below. Comment is invited on the details of these determinations.

( 1) No criteria are proposed for States which have been fully approved by EPA as complying with the section 303( c)( 2)( B) requirements.

( 2) For States which have not been fully approved, if EPA has not previously determined which specific pollutants/ criteria/ waterbodies are lacking from a State's standards ( i. e., as part of an approval/ disapproval action only), all of the criteria in columns B, C, and D of the proposed Sec. 131.36( b) matrix are proposed for statewide application to all appropriate designated uses, except as provided for elsewhere in these rules. That is, EPA proposes to bring the State into compliance with section 303( c)( 2)( B) via an approach which is comparable to option 1 of the December 1988 national guidance for section 303( c)( 2)( B).

( 3) If EPA has previously determined which specific pollutants/ criteria/ waterbodies are needed to comply with CWA section 303( c)( 2)( B) ( i. e., as part of an approval/ disapproval action only), the criteria in proposed section 131.36( b) are proposed for only those specific pollutants/ criteria/ waterbodies ( i. e., EPA proposes to bring the State into compliance via an approach which is comparable to option 2 of the December 1988 national guidance for section 303( c)( 2)( B)).

( 4) For aquatic life, except as provided for elsewhere in these rules, all waters with designated aquatic life uses providing even minimal support to aquatic life are included in the proposed rule ( i. e., fish survival, marginal aquatic life, etc.).

( 5a) For human health, except as provided for elsewhere in these rules, all waters with designated uses providing for public water supply protection ( and therefore a potential water consumption exposure route) or minimal aquatic life protection ( and therefore a potential fish consumption exposure route) are included in the proposed rule.

( 5b) Where a State has determined the specific aquatic life segments which provide a fish consumption exposure route ( i. e., fish or other aquatic life are being caught and consumed) and EPA approved this determination as part of standards approval/ disapproval action, the proposed rule includes the fish consumption ( Column D( II)) criteria for only those aquatic life segments, except as provided for elsewhere in these rules. In making a determination that certain segments do not support a fish consumption exposure route, a State must have completed, and EPA approved, a use attainability analysis consistent with the provisions of 40 CFR 131.10( j). In the absence of such an approved State determination, EPA has proposed fish consumption criteria for all aquatic life segments.

( 6) Uses/ Classes other than those which support aquatic life or human health are not included in the proposed rulemaking ( e. g., livestock watering, industrial water supply), unless they are defined in the State standards as also providing protection to aquatic life or human health ( i. e., unless they are described as protecting multiple uses including aquatic life or human health). For example, if the State standards include a use such as industrial water supply, and in the narrative description of the use the State standards indicate that the use includes protection for resident aquatic life, then this use is included in the proposed rulemaking.

( 7) For human health, the " water+ fish" criteria in Column D( I) of Sec. 131.36( b) are proposed for all waterbodies where public water supply and aquatic life uses are designated, except as provided for elsewhere in these rules ( e. g., rule 9).

( 8) If the State has public water supplies where aquatic life uses have not been designated, or public water supplies that have been determined not to provide a potential fish consumption exposure pathway, the " water only" criteria in Column D( I) of Sec. 131.36( b) are proposed for such waterbodies, except as provided for elsewhere in these rules ( e. g., rule 9). ( 9) EPA is generally not proposing criteria for priority toxic pollutants for which a State has adopted criteria and received EPA approval. The exceptions to this general rule are described in rules 10 and 11.

( 10) For priority toxic pollutants where the State has adopted human health criteria and received EPA approval, but such criteria do not fully satisfy section 303( c)( 2)( B) requirements, the proposed rule includes human health criteria for such pollutants. For example, consider a case where a State has a water supply segment that poses an exposure risk to human health from both water and fish consumption. If the State has adopted, and received approval for, human health criteria based on water consumption only ( e. g., Safe Drinking Water Act Maximum Contaminant Levels ( MCLs)) which are less stringent than the " water+ fish" criteria in Column D( I) of proposed Sec. 131.36( b), the Column D( I) criteria are proposed for those water supply segments. The rationale for this is to ensure that both water and fish consumption exposure pathways are adequately addressed and human health is fully protected. If the State has adopted water consumption only criteria which are more stringent or equal to the Column D( I) criteria, the " water+ fish" criteria in Column D( I) criteria are not proposed. ( 11) For priority toxic pollutants where the State has adopted aquatic life criteria and previous to the 1987 CWA Amendments received EPA approval, but such criteria do not fully satisfy section 303( c)( 2)( B) requirements, the proposed rule includes aquatic life criteria for such pollutants. For example, if the State has adopted not to be exceeded aquatic life criteria which are less stringent than the 4 day average chronic aquatic life criteria in Sec. 131.36( b) ( i. e., in Columns B( II) and C( II)), the acute and chronic aquatic life criteria in Section 131.36( b) are proposed for those pollutants.

The rationale for this is that the State adopted criteria do not protect resident aquatic life from both acute and chronic effects, and that Federal criteria are necessary to fully protect aquatic life designated uses. If the State has adopted not to be exceeded aquatic life criteria which are more stringent or equal to the chronic aquatic life criteria in Sec. 131.36( b), the acute and chronic aquatic life criteria in Sec. 131.36( b) are not proposed for those pollutants.

( 12) Under certain conditions discussed in rules 9, 10, and 11, criteria listed in Sec. 131.36( b) are not proposed for specific pollutants; however, EPA made such exceptions only for pollutants for which criteria have been adopted by the State and approved by EPA, where such criteria are currently effective under State law the appropriate EPA Region concluded that the State's criteria fully satisfy section 303( c)( 2)( B) requirements.

3. Approach for States That Fully Comply Subsequent to Issuance of Today's Proposed Rulemaking As discussed in prior sections of this preamble, the water quality standards program has been established with an emphasis on State primacy. Although this proposed rule has been developed to Federally promulgate toxics criteria for States, EPA prefers that States maintain primacy, revise their own standards, and achieve full compliance. EPA is hopeful that today's proposed rulemaking will provide additional impetus for non complying States to adopt the criteria for priority toxic pollutants necessary to comply with section 303( c)( 2)( B).

For States that achieve full compliance before publication of the final rulemaking, EPA will not include such States in the final rulemaking. At any point in the process prior to final promulgation, a State can ensure that it will not be affected by this action by adopting the necessary criteria pursuant to State law and receiving EPA approval. The content of the adopted standards must be within the boundaries of the several acceptable approaches described earlier in this preamble.

Following a final promulgation of this rule, removal of a State from the rule will require rulemaking by EPA according to the requirements of the Administrative Procedure Act ( 5 U. S. C. 551 et seq.). EPA will withdraw the Federal rule without a notice and comment rulemaking when the State adopts standards no less stringent than the Federal rule ( i. e., standards which provide, at least, equivalent environmental protection). For example, see 51 FR 11580, April 4, 1986, which finalized EPA's removal of a Federal rule for the State of Mississippi.

However, if a State adopts standards for toxics which are less stringent than the Federal rule but, in the Agency's judgment, fully meet the requirements of the Act, EPA will propose to withdraw the rule with a notice of proposed rulemaking and provide for public participation. This procedure would be required for partial or complete removal of a State from this rulemaking. A State covered by the final rule could adopt the necessary criteria using any of the three options or combinations of those Options described in EPA's 1989 guidance.

EPA cautions States and the public that promulgation of a Federal rule removes most of the flexibility available to States for modifying their standards on a discharger specific or stream specific basis. For example, variances, site specific criteria and schedules of compliance actions pursuant to State law for federally promulgated criteria are precluded. Each of these types of modifications would require Federal rulemaking on a case by case basis to change the Federal rule for that State.

F. Derivation of Proposed Criteria 1. Sections 304( a) Criteria Process Under the authority of CWA section 304( a) EPA has developed methodologies and specific criteria to protect aquatic life and human health. These methodologies are intended to provide protection for all surface water on a national basis. As described below, there are site specific procedures for more precisely addressing site specific conditions for an individual water body. However, these site specific criteria procedures are infrequently used because the section 304( a) criteria recommendations have proven themselves to be appropriate for the vast majority of water bodies. The methodologies have been subject to public review, as have the individual criteria documents. Additionally, the methodologies have been reviewed and approved by EPA's Science Advisory Board.

EPA incorporates by reference into the record of this proposed rulemaking the aquatic life methodology as described in " Appendix B Guidelines for Deriving Water Quality Criteria for the Protection of Aquatic Life and Its Uses" ( 45 FR 79341, November 28, 1980) as amended by " Summary of Revisions to Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses" ( 50 FR 30792, July 29, 1985). EPA also incorporates by reference into the record of this proposed rulemaking the human health methodology as described in " Appendix C Guidelines and Methodology Used in the Preparation of Health Effects Assessment Chapters of the Consent Decree Water Criteria Documents" ( 45 FR 79347, November 28, 1980). EPA also recommends that the following be reviewed for information: " Appendix D Response to Comments on Guidelines for Deriving Water Quality Criteria for the Protection of Aquatic Life and Its Uses," ( 45 FR 79357, November 28, 1980); " Appendix E Responses to Public Comments on the Human Health Effects Methodology for Deriving Ambient Water Quality Criteria" ( 45 FR 79368, November 28, 1980); and " Appendix B Response to Comments on Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses" ( 50 FR 30793, July 29, 1985). EPA also is placing into the record the most current individual criteria documents for the priority toxic pollutants included in today's proposal.

The primary focus of this rule is the inclusion of the water quality criteria for pollutant( s) in State standards as necessary to support water quality based control programs. The Agency is accepting comment on the criteria proposed in today's rule. However, Congress has established a very ambitious schedule for the promulgation of the final criteria. The statutory deadline in section 303( c)( 4) clearly indicates that Congress intended the Agency to move very expeditiously when Federal action is warranted. The Agency believes that the limited time available for promulgation of the regulation can be used most efficiently and effectively by addressing those issues that have not already come before the Agency. The methodology used to develop the criteria and the criteria themselves ( to the extent not updated through IRIS) have previously undergone scientific peer review and public review and comment, and have been revised as appropriate. For the most part, this review occurred before Congress amended the Act in 1987, to require the inclusion of numeric criteria for certain toxic pollutants in State standards. Congress acted with full knowledge of the EPA process for developing criteria and the Agency's recommendations under section 304( a). EPA believes it is consistent with Congressional intent to rely in large part on existing criteria rather than engage in a time consuming reevaluation of the underlying basis for water quality criteria. Accordingly, the Agency does not intend in this rulemaking to address the issues that have already been addressed by the Agency in response to previous comments. It is the Agency's belief that this approach will best achieve the purpose of moving forward in promulgating criteria for States not in compliance with section 303( c)( 2)( B) so that environmental controls intended by Congress can be put into place to protect public health and welfare and enhance water quality.

It should be noted that the Agency is initiating a review of the basic guidelines for developing criteria and that comments received in this rulemaking may be of value in that effort as well. Future revisions to the criteria guidelines will be reviewed by the Agency's Science Advisory Board and submitted to the public for review and comment following the same process that was used in issuing the existing methodological guidelines. Subsequent revisions of criteria documents and the issuance of any new criteria documents will also be subject to public review.

2. Aquatic Life Criteria Aquatic life criteria may be expressed in numeric or narrative forms. EPA's guidelines describe an objective, internally consistent and appropriate way of deriving chemical specific, numeric water quality criteria for the protection of the presence of, as well as the uses of, both fresh and marine water aquatic organisms.

An aquatic life criterion derived using EPA's section 304( a) method represents an estimate of the highest concentration of a pollutant in water that does not present a significant risk to aquatic organisms per se or to their use. EPA's guidelines are designed to derive criteria that protect aquatic communities by protecting most of the species and their uses most of the time, but not necessarily all of the species all of the time. Aquatic communities can tolerate some stress and occasional adverse effects on a few species so that total protection of all species all of the time is not necessary. EPA's guidelines attempt to provide a reasonable and adequate amount of protection with only a small possibility of substantial overprotection or underprotection. As discussed in detail below, there are several individual factors which may make the criteria somewhat overprotective or underprotective. Clearly, addressing them all is probably infeasible and, in any case, would make the criteria derivation process unduly resource intensive and time consuming. The approach EPA is using is believed to be as well balanced as possible, given the state of the science.

Numerical aquatic life criteria derived using EPA's most recent guidelines are expressed as short term and long term numbers, rather than one number, in order that the criteria more accurately reflect toxicological and practical realities. The combination of a criteria maximum concentration ( CMC), a one hour average acute limit, and a criteria continuous concentration ( CCC), a four day average concentration chronic limit, provide protection of aquatic life and its uses from acute and chronic toxicity to animals and plants, and from bioconcentration by aquatic organisms, without being as restrictive as a one number criterion would have to be.

The two number criteria are intended to identify average pollutant concentrations which will produce water quality generally suited to maintenance of aquatic life and their uses while restricting the duration of excursions over the average so that total exposures will not cause unacceptable adverse effects. Merely specifying an average value over a time period is insufficient unless the time period is short, because excursions higher than the average can kill or cause substantial damage in short periods. EPA's guidelines were developed on the assumption that the results of laboratory tests are generally useful for predicting what will happen in field situations. Certain ambient waters may have some capacity to bind pollutants and make them less bioavailable. The site specific criteria process provides a means of addressing this effect ( i. e., by allowing development and use of a " water effect ratio" that quantifies the difference in toxicity of a pollutant in site water versus the toxicity of the pollutant in the laboratory water used to develop the section 304( a) criteria recommendation). However, in the absence of such an approach, the criteria may be somewhat overprotective in some situations.

A minimum data set of eight specified families is required for criteria development ( details are given in the methodology cited above). The eight specific families are intended to be representative of a wide spectrum of aquatic life. For this reason it is not necessary that the specific organisms tested be actually present in the water body. States may develop site specific criteria using native species, provided that the broad spectrum represented by the eight families is maintained. All aquatic organisms and their common uses are meant to be considered, but not necessarily protected, if relevant data are available.

EPA's application of guidelines to develop the criteria matrix in the proposed rule is judged by the Agency to be applicable to all waters of the United States, and to all ecosystems. There are waters and ecosystems where site specific criteria could be developed, as discussed below, but it is up to States to identify those waters and develop the appropriate site specific criteria.

Fresh water and salt water ( including both estuarine and marine waters) have different chemical compositions, and freshwater and saltwater species rarely inhabit the same water simultaneously. To provide additional accuracy, criteria developed recently are developed for fresh water and for salt water.

Assumptions which may make the criteria underprotective include the use of criteria on an individual basis, with no consideration of additive or synergistic effects, and the general lack of consideration of impacts on wildlife, due principally to a lack of data.

3. Criteria for Human Health As with aquatic life, EPA's guidelines for human health criteria attempt to provide a reasonable and adequate amount of protection with only a small possibility of substantial overprotection or underprotection. EPA's section 304( a) criteria for human health are based on two types of biological endpoints: ( 1) Carcinogenicity and ( 2) systemic toxicity ( i. e., all other adverse effects other than cancer). Thus, there are two procedures for assessing these health effects: One for carcinogens and one for non carcinogens.

EPA's guidelines assume that carcinogenicity is a " non threshold phenomenon," that is, there are no " safe" or " no effect levels" because even extremely small doses are assumed to cause a finite increase in the incidence of the response ( i. e., cancer). Therefore, EPA's water quality criteria for carcinogens are presented as pollutant concentrations corresponding to increases in the risk of developing cancer.

For pollutants that do not manifest any apparent carcinogenic effects in animal studies ( i. e., systemic toxicants), EPA assumes that the pollutant has a threshold below which no effects will be observed. This assumption is based on the premise that a physiological mechanism exists within living organisms to avoid or overcome the adverse effects of the pollutant below the threshold concentration.

The human health risks of a substance cannot be determined with any degree of confidence unless dose response relationships are quantified. Therefore, a dose response assessment is required before a criterion can be calculated. The dose response assessment determines the quantitative relationships between the amount of exposure to a substance and the onset of toxic injury or disease. Data for determining dose response relationships are typically derived from animal studies, or less frequently, from epidemiological studies in exposed populations.

The dose response information needed for carcinogens is an estimate of the carcinogenic potency of the compound. Carcinogenic potency is defined here as a general term for a chemical's human cancer causing potential. This term is often used loosely to refer to the more specific carcinogenic or cancer slope factor which is defined as an estimate of carcinogenic potency derived from animal studies or epidemiological data of human exposure. It is based on extrapolation from test exposures of high dose levels over relatively short periods of time to more realistic low dose levels over a lifetime exposure period by use of linear extrapolation models. The cancer slope factor, q1*, is EPA's estimate of carcinogenic potency and is intended to be a conservative upper bound estimate ( e. g. 95% upper bound confidence limit).

For non carcinogens, EPA uses the reference dose ( RfD) as the dose response parameter in calculating the criteria. The RfD was formerly referred to as an " Acceptable Daily Intake" or ADI. The RfD is useful as a reference point for gauging the potential effects of other doses. Doses that are less than the RfD are not likely to be associated with any health risks, and are therefore less likely to be of regulatory concern. As the frequency of exposures exceeding the RfD increases and as the size of the excess increases, the probability increases that adverse effects may be observed in a human population. Nonetheless, a clear conclusion cannot be categorically drawn that all doses below the RfD are " acceptable" and that all doses in excess of the RfD are " unacceptable." In extrapolating non carcinogen animal test data to humans to derive an RfD, EPA divides a no observed effect dose observed in animal studies by an " uncertainty factor" which is based on professional judgment of toxicologists and typically ranges from 10 to 10,000.

For section 304( a) criteria development, EPA typically considers only exposures to a pollutant that occur through the ingestion of waters and contaminated fish and shellfish. Thus the criteria are based on an assessment of risks related to the surface water exposure route only.

The assumed exposure pathways in calculating the criteria are the consumption of 2 liters per day at the criteria concentration and the consumption of 6.5 grams per day of fish/ shellfish contaminated at a level equal to the criteria concentration but multiplied by a " bioconcentration factor." The use of fish consumption as an exposure factor requires the quantification of pollutant residues in the edible portions of the ingested species. Bioconcentration factors ( BCFs) are used to relate pollutant residues in aquatic organisms to the pollutant concentration in ambient waters. BCFs are quantified by various procedures depending on the lipid solubility of the pollutant. For lipid soluble pollutants, the average BCF is calculated from the weighted average percent lipids in the edible portions of fish/ shellfish, which is about 3%; or it is calculated from theoretical considerations using the octanol/ water partition coefficient. For non lipid soluble compounds, the BCF is determined empirically. The assumed water consumption is taken from the National Academy of Sciences publication " Drinking Water and Health" ( 1977). The 6.5 grams per day contaminated fish consumption value is equivalent to the average per capita consumption rate of all ( contaminated and non contaminated) freshwater and estuarine fish for the U. S. population.

EPA also assumes in calculating water quality criteria that the exposed individual is an average adult with body weight of 70 kilograms. The issue of concern is dose per kilogram of body weight. EPA assumes 6.5 grams per day of contaminated fish consumption and 2 liters per day of contaminated drinking water consumption for a 70 kilogram person in calculating the criteria. Persons of smaller body weight are expected to ingest less contaminated fish and water, so the dose per kilogram of body weight is generally expected to be roughly comparable. There may be subpopulations within a State, such as subsistence fishermen, who as a result of greater exposure to a contaminant, are at greater risk than the hypothetical 70 kilogram person eating 6.5 grams per day of maximally contaminated fish and shellfish and drinking 2 liters per day of maximally contaminated drinking water. ( EPA is in part addressing the potential that highly exposed subpopulations exist by selecting a relatively stringent cancer risk level ( 10 6) for use in deriving State wide criteria for carcinogens. Individuals that ingest ten times more of a pollutant than is assumed in derivation of the criteria will be protected to a 10 5 level, which EPA has historically considered to be adequately protective. There may, nevertheless, be circumstances where site specific numeric criteria that are more stringent than the State wide criteria are necessary to adequately protect highly exposed subpopulations. Although EPA intends in this initial promulgation to focus on promulgation of appropriate State wide criteria that will reduce risks to all exposed individuals, including highly exposed subpopulations, site specific criteria may be developed subsequently by EPA or the States where warranted to provide necessary additional protection.) For non carcinogens RfDs are developed based on pollutant concentrations that cause threshold effects. The RfD is an estimate ( with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population ( including sensitive subgroups) that is likely to be without appreciable risk of deleterious effects during a lifetime.

Criteria are calculated for individual chemicals with no consideration of additive, synergistic or antagonistic effects in mixtures. If the conditions within a State differ from the assumptions EPA used, the States have the option to perform the analyses for their conditions.

EPA has a process to develop a scientific consensus on oral reference doses and carcinogenic slope factors. Reference doses and slope factors are validated by two Agency work groups ( i. e., one work group for each) which are composed of senior Agency scientists from all of the program offices and the Office of Research and Development. These work groups develop a consensus of Agency opinion for Rfds and slope factors which are then used throughout the Agency for consistent regulation and guidance development. EPA maintains an electronic data base which contains the official Agency consensus for Rfd's and slope factors which is known as the Integrated Risk Information System ( IRIS). It is available for use through EPA's electronic mail system, and also available through the Public Health Network of the Public Health Foundation, and on the National Institutes of Health National Library of Medicine's TOXNET system. For the criteria included in today's proposal, EPA used the criteria recommendation from the appropriate section 304( a) criteria document. ( The availability of EPA's criteria documents has been announced in various Federal Register notices. These documents are also placed in the record for today's proposed rule.) However, if the Agency has changed in IRIS any parameters used in criteria derivation since issuance of the criteria guidance document, EPA recalculated the criteria recommendation with the latest information. ( This information is included in the record.) Thus, there may be differences between the original recommendation, and those in today's proposal, but today's proposal presents the Agency's most current section 304( a) criteria recommendation. The recalculated human health numbers are denoted by an " a" in the criteria matrix in subsection 131.36( b) of today's proposed rule.

In order to base its regulatory decisions on the best available science, EPA continuously updates its assessment of the risk from exposure to contaminants. On September 11, 1991, EPA's Office of Research and Development ( ORD) began reassessing the scientific models and exposure scenarios used to predict the risks of biological effects from exposure to low levels of dioxin. This reassessment has the potential to alter the risk assessment for dioxin and accordingly the Agency's regulatory decisions related to dioxin. At this time, EPA is unable to say with any certainty what the degree or directions of any changes in risk estimates might be. This rulemaking includes a proposed Agency action with regard to dioxin that may be affected by the reassessment. The Agency will be carefully monitoring ORD's efforts in order to ensure that appropriate actions are taken during the course of this rulemaking to reflect any necessary changes resulting from the reassessment. If a final Agency action on this rulemaking occurs prior to completion of ORD's work, the Agency will consider revisiting that decision.

4. Section 304( a) Human Health Criteria Excluded Today's proposal does not contain certain of the Section 304( a) criteria for priority toxic pollutants because those criteria were not based on toxicity. The basis for these particular criteria are organoleptic effects ( e. g., taste and odor) which would make water and edible aquatic life unpalatable but not toxic. Because the basis for this proposed rulemaking is to protect the public health and aquatic life from toxicity consistent with the language in section 303( c)( 2)( B), EPA is proposing criteria only for those priority toxic pollutants whose criteria recommendations are based on toxicity. The Section 304( a) human health criteria based on organoleptic effects for copper, zinc, 2,4 dimethylphenol, and 3 methyl 4 chlorophenol are excluded for this reason.

5. Cancer Risk Level Proposed EPA's Section 304( a) criteria guidance documents for priority toxic pollutants which are based on carcinogenicity present concentrations for upper bound risk levels of 1 excess cancer per 100,000 people ( 10 5), per 1,000,000 people ( 10 6), and per 10,000,000 people ( 10 7). However, the criteria documents do not recommend a particular risk factor as EPA policy.

In the April, 1990, Federal Register notice of preliminary assessment of State compliance, EPA announced the intention to include in the proposed rulemaking an incremental cancer risk level of one in a million ( 10 6) for all priority toxic pollutants regulated as carcinogens. That cancer risk level is reflected in this proposed rule. The reasons supporting this decision are discussed below. However, EPA's Office of Water's guidance to the States has consistently reflected the Agency's policy of accepting cancer risk policies from the States in the range of 10 6 to 10 4. EPA reviews individual State policies as part of its water quality standards oversight function and determines if States have appropriately consulted its citizens and applied good science in adopting water quality criteria.

First, EPA's human health criteria have been developed based on a number of exposure assumptions. Many of these assumptions are based on the exposure for an average individual. For example, EPA's criteria assumes exposure of a 70 kilogram ( 154 pound) adult who consumes 2 liters ( 2.1 quarts) of water per day and 6.5 grams of fish per day ( less than 7 ounces per month). These assumptions are based on approximate national averages, but considerably understate the exposure that would occur for certain segments of the population that have high fish consumption or depend on fish consumption for subsistence. Similarly, it would overstate the exposure of those who consume less fish than the National average amount. Therefore, although EPA would accept a lower State adopted risk level, in the range of 10 4 to 10 6, EPA has chosen a 10 6 risk level to protect the average exposed individual at a conservative incremental lifetime cancer risk.

A second strong reason is that a 10 6 risk level is consistent with what most States have selected, or are expected to select, as their risk level. A recent EPA status report on State compliance with section 303( c)( 2)( B) found that 36 of the 57 States and Territories will select 10 6 as their risk level ( 12 States have selected or are expected to select 10 5 and 9 of the remaining States are undecided). EPA's proposal is therefore consistent with the majority of the States, does not contradict those States choosing a 10 6 risk level and does not preclude States from eventually choosing a risk level below 10 6.

Third, by selecting a risk level of 10 6 for the average exposed individual, some assurance is provided against the possibility that current section 304( a) criteria are not sufficiently stringent. The various parameters used in deriving the Section 304( a) criteria ( e. g. cancer potency slopes, reference doses, bioaccumulation factors, etc.) are based on the state of present science. With additional research and experience, EPA may find that one or more of these factors understates the actual public risk. In addition, in many cases, EPA's criteria are based upon a single health effect. As the science evolves and available information expands, there is the potential that EPA will determine that other endpoints or effects are more sensitive than those currently considered. This risk level also reflects a recognition that certain factors are not considered in the current criteria methodology.

A proposed 10 6 risk level does not preclude State alternatives. If a State decides that a different risk level is more appropriate, it may avoid Federal promulgation by completing its standards adoption process in compliance with section 303( c)( 2)( B). As discussed earlier, this would be the case both in advance of or subsequent to final promulgation. 6. Applying EPA's Nationally Derived Criteria to State Waters To assist States in modifying EPA's water quality criteria, the Agency has provided guidance on developing site specific criteria for aquatic life and human health ( see Water Quality Standards Handbook and the Guidelines for Deriving Numerical National Water Quality Criteria). This guidance can be used by the appropriate regulatory authority to develop alternative criteria. Where such criteria are more stringent than the criteria finally developed pursuant to this proposed rulemaking, section 510 of the Clean Water Act ( 33 U. S. C. 1370) provides authority for their implementation and enforcement in lieu of today's proposed criteria.

EPA's experience with such site specific criteria has verified that the national criteria are generally protective and appropriate for direct use by the States.

G. Description of the Proposed Rule EPA's final rule would establish a new Sec. 131.36 in 40 CFR part 131 entitled, " Toxics Criteria for Those States Not Fully Complying With Clean Water Act section 303( c)( 2)( B)."

1. Scope Subsection ( a), entitled " Scope", clarifies that this section is not a general promulgation of the section 304( a) criteria for priority toxic pollutants but is restricted to specific pollutants in specific States.

2. EPA Criteria for Priority Toxic Pollutants Subsection ( b) presents a matrix of the applicable EPA criteria for priority toxic pollutants. Section 303( c)( 2)( B) of the Act addresses only pollutants listed as " toxic" pursuant to section 307( a) of the Act. As discussed earlier in this preamble, the section 307( a) list of toxics contains 65 compounds and families of compounds, which potentially include thousands of specific compounds. The Agency uses the list of 126 " priority toxic pollutants" for administrative purposes ( see 40 CFR part 423, appendix A). Reference in this proposed rule to priority toxic pollutants, toxic pollutants, or toxics refers to the 126 priority toxic pollutants.

However, EPA has not developed both aquatic life and human health section 304( a) criteria for all of the 126 priority toxic pollutants. The matrix in paragraph ( b) contains human health criteria in Column D for 102 priority toxic pollutants which are divided into criteria ( Column I) for water consumption ( i. e., 2 liters per day) and aquatic life consumption ( i. e., 6.5 grams per day of aquatic organisms), and Column II for aquatic life consumption only. The term aquatic life includes fish and shellfish such as shrimp, clams, oysters and mussels. The total number of priority toxic pollutants with criteria proposed today differs from the total number of priority toxic pollutants with section 304( a) criteria because EPA has developed and is proposing chromium criteria for two valence states. Thus, although chromium is a single priority toxic pollutant, there are two criteria for chromium. See numbers 5a and 5b in proposed Sec. 131.36( b).

The matrix contains aquatic life criteria for 30 priority pollutants. These are divided into freshwater criteria ( Column B) and saltwater criteria ( Column C). These columns are further divided into acute and chronic criteria. The aquatic life criteria are considered by EPA to be protective when applied under the conditions described in the section 304( a) criteria documents and in the " Technical Support Document for Water Quality based Toxics Control." For example, waterbody uses should be protected if the criteria are not exceeded, on average, once every three year period. It should be noted that the criteria maximum concentrations ( the acute criteria) are one hour average concentrations and that the criteria continuous concentrations ( the chronic criteria) are four day averages. It should also be noted that for certain of the metals, the actual criteria are equations which are included as footnotes to the matrix. The toxicity of these metals are water hardness dependent. The values shown in the table are based on a hardness expressed as calcium carbonate of 100 mg/ l. Finally, the criterion for pentachlorophenol is pH dependent. The equation is the actual criterion and is included as a footnote. The value shown in the matrix is for a pH of 7.8 units.

Several of the freshwater aquatic life criteria are incorporated into the matrix in the format used in the 1980 criteria methodology. This distinction is noted in footnote ( g) to the table. EPA has not updated these criteria for various reasons. Footnote ( g) describes an approximate method to translate these 1980 criteria to the equivalent criteria by the 1985 methodology. EPA could make this translation in a final rule and solicits public comment on which approach is better.

The matrix also includes toxicity based human health criteria for copper, 2 chloroethylvinyl ether, 1,2 trans dichloroethylene, 2 chlorophenol, acenaphthene, butylbenzyl phthalate, and N nitrosodi n propylamine. The criteria for these substances are shown in parentheses and are not being proposed today but are included for informational purposes and as notice for consideration in all future State triennial reviews. Although sufficient information on these compounds was previously unavailable to calculate a section 304( a) criterion based on carcinogenicity or systemic toxicity, Agency approved information in IRIS now allow calculation of these criteria using the EPA criteria guidelines. EPA has assembled another matrix which provides all of the factors used to calculate the proposed human health criteria. This supplementary matrix is included in the record for this proposal.

3. Applicability Section 131.36( d) establishes the applicability of the criteria proposed for each included State. It provides that the criteria promulgated for each State supersede and/ or complement any State criteria for that toxic pollutant. EPA believes it has not proposed to supersede any State criteria for priority toxic pollutants unless the State adopted criteria are disapproved or otherwise insufficient. The approach followed by the Agency in preparing proposed Sec. 131.36( d) is described in section E. 2, and further rationale is provided in section E. 3 of this preamble. EPA invites comment on the accuracy of the Agency's decisions to include or exclude particular priority toxic pollutant criteria.

EPA's principal purpose today is to propose the toxics criteria necessary to comply with section 303( c)( 2)( B). However, in order for such criteria to achieve their intended purpose the implementation scheme must be such that the final results protect the public health and welfare. In section F of this preamble a discussion focused on the factors in EPA's assessment of criteria for carcinogens. For example, fish consumption rates, bioaccumulation factors, and cancer potency slopes were discussed. When any one of these factors is changed, the others must also be evaluated so that, on balance, resulting criteria are adequately protective.

Once an appropriate criterion is selected for either aquatic life or human health protection, then appropriate conditions for calculating water quality based effluent limits for that chemical must be established in order to maintain the intended stringency and achieve the necessary toxics control. EPA has included in this proposal appropriate implementation factors necessary to maintain the level of protection intended. These proposals are included in subsection ( c).

For example, most States have low flow values for streams and rivers which establish flow rates below which numeric criteria may be exceeded. These low flow values became design flows for sizing treatment plants and developing water quality based effluent limits. Historically, these so called " design" flows were selected for the purposes of waste load allocation analyses which focused on instream dissolved oxygen concentrations and protection of aquatic life. With the publication of the 1985 Technical Support Document for Water Quality Based Toxics Control ( TSD), EPA introduced hydrologically and biologically based analyses for the protection of aquatic life and human health./ 1/ EPA recommended either of two methods for calculating acceptable low flows, the traditional hydrologic method developed by the U. S. Geological Survey and a biological based method developed by EPA. The results of either of these two methods may be used. NOTE / 1/ These concepts have been expanded subsequently in guidance entitled " Technical Guidance Manual for Performing Wasteload Allocations, Book 6, Design Conditions," USEPA, Office of Water Regulations and Standards, Washington, DC ( 1986). These new developments are included in appendix D of the revised TSD. The discussion here is greatly simplified and is provided to support EPA's decision to propose baseline application values for instream flows and thereby maintain the intended stringency of the criteria for priority toxic pollutants.

Some States have adopted specific low flow requirements for streams and rivers to protect designated uses against the effects of toxics. Generally these have followed the guidance in the TSD. However, EPA believes it is essential to include proposed design flows in today's proposed rule so that, where States have not yet adopted such design flows, the criteria proposed today would be implemented appropriately. Clearly, if the proposed criteria were implemented using inadequate design flows, the resulting toxics controls would not be fully effective, because the resulting ambient concentrations would exceed EPA's recommended levels.

In the case of aquatic life, more frequent violations than the once in 3 years assumed exceedences would result in diminished vitality of stream ecosystems characteristics by the loss of desired species such as sport fish. The low flow values proposed are:

Aquatic Life: Acute criteria ( CMC) 1 Q 10 or 1 B 3. Chronic criteria ( CCC) 7 Q 10 or 4 B 3. Human Health: Non carcinogens 30 Q 5. Carcinogens harmonic mean flow.

Where:

1 Q 10 is the lowest one day flow with an average recurrence frequency of once in 10 years determined hydrologically; 1 B 3 is biologically based and indicates an allowable exceedence of once every 3 years. It is determined by EPA's computerized method ( DFLOW model); 7 Q 10 is the lowest average 7 consecutive day low flow with an average recurrence frequency of once in 10 years determined hydrologically; 4 B 3 is biologically based and indicates an allowable exceedence for 4 consecutive days once every 3 years. It is determined by EPA's computerized method ( DFLOW model); 30 Q 5 is the lowest average 30 consecutive day low flow with an average recurrence frequency of once in 5 years determined hydrologically; and The harmonic mean flow is a long term mean flow value calculated by dividing the number of daily flows analyzed by the sum of the reciprocals of those daily flows.

EPA is proposing the harmonic mean flow to be applied with human health criteria. The concept of a harmonic mean is a standard statistical data analysis technique. EPA's model for human health effects assumes that such effects occur because of a long term exposure to low concentration of a toxic pollutant. For example, two liters of water per day for seventy years. To estimate the concentrations of the toxic pollutant in those two liters per day by withdrawal from streams with a high daily variation in flow, EPA believes the harmonic mean flow is the correct statistic to use in computing such design flows rather than other averaging techniques./ 2/

NOTE / 2/ For a description of harmonic means see " Design Stream Flows Based on Harmonic Means," Lewis A. Rossman, J. of Hydraulics Engineering, Vol. 116, No. 7, July, 1990. This article is contained in the record for this proposal. All waters, whether or not suitable for such hydrologic calculations but included in this proposed rule ( including lakes, estuaries, and marine waters), must contain the criteria proposed today. Such attainment must occur at the end of the discharge pipe, unless the State has an EPA approved mixing zone regulation. If the State has an EPA approved mixing zone regulation, then the criteria would apply at the locations stated in that regulation. For example, the chronic criteria ( CCC) must apply at the geographically defined boundary of the mixing zone. Discussion and guidance of these factors are included in the revised TSD in chapter 4.

EPA is aware that the criteria proposed today for some of the priority toxic pollutants are at concentrations less than EPA's current analytical detection limits. Detection limits have never been an acceptable basis for setting standards since they are not related to actual environmental impacts. The environmental impact of a pollutant is based on a scientific determination, not an arbitrary measuring technique which is subject to change. Setting the criteria at levels that reflect adequate protection tends to be a forcing mechanism to improve analytical detection methods. As the methods improve, limits closer to the actual criteria necessary to protect aquatic life and human health are measurable. The Agency does not believe it is appropriate to promulgate insufficiently protective criteria ( e. g., criteria equal to the current analytical detection limits).

EPA does believe, however, that the use of analytical detection limits are appropriate for determining compliance with NPDES permit limits. This historical view of the role of detection limits was recently articulated in guidance for translating dioxin criteria into NPDES permit limits which is the principal method used for water quality standards enforcement./ 3/ This guidance presents a model for addressing toxic pollutants which have criteria recommendations less than current detection limits. This guidance is equally applicable to other priority toxic pollutants with criteria recommendations less than current detection limits. The guidance explains that detection limits may be used for purposes of determining compliance with permit limits, but not for purposes of establishing water quality criteria or permit limits. Because under the Clean Water Act analytical detection limits are appropriately used only in connection with NPDES permit limit compliance determinations, EPA has not considered analytical detection limits in deriving the criteria proposed today.

NOTE / 3/ Strategy for the Regulation of Discharges of PHDDs and PHDFs from Pulp and Paper Mills to Waters of the United States," memorandum from the Assistant Administrator for Water to the Regional Water Management Division Directors and NPDES State Directors, May 21, 1990.

EPA has added provisions in paragraph ( c)( 3) to determine when fresh water or saltwater aquatic life criteria apply. The structure of the paragraph is to establish presumptively applicable rules and to allow for site specific determinations where the rules are not consistent with actual field conditions. Because a distinct separation generally does not exist between fresh water and marine water aquatic communities, EPA is proposing the following: ( 1) The fresh water criteria apply at salinities of 1 part per thousand and below; ( 2) marine water criteria apply at 10 parts per thousand and above; and ( 3) at salinities between 1 and 10 parts per thousand the more stringent of the two apply unless EPA approves another site specific criterion for the pollutant. This proposed assignment of criteria for fresh, brackish and marine waters was developed in consultation with EPA's research laboratories at Duluth, Minnesota and Narragansett, Rhode Island. The Agency believes such an approach is consistent with field experience.

In paragraph ( c)( 4)( i) EPA has included a limitation on the amount of hardness that EPA can allow to antagonize the toxicity of certain metals ( see footnote ( e) in the criteria matrix in paragraph ( b) of the rule). The data base used for the Section 304( a) criteria documents for metals do not include data supporting the extrapolation of the hardness effects on metal toxicity beyond a range of hardness of 25 mg/ l to 400 mg/ l ( expressed as calcium carbonate). Thus, the aquatic life values for the CNC ( acute) and CCC ( chronic) criteria for these metals in waters with a hardness less than 25 mg/ l, must nevertheless use 25 mg/ l when calculating the criteria; and in waters with a hardness greater than 400 mg/ l, must nevertheless use 400 mg/ l when calculating the criteria.

Subsection ( d) lists the States for which rules are being proposed. For each identified State, the water uses impacted ( and in some cases the waters covered) and the criteria proposed are identified.

H. Specific Issues for Public Comment As is the Agency's custom, EPA would like to request that particular public review be directed to the issues and alternatives presented in this section. Although the issues presented below are particularly notable and worthy of comment, EPA encourages public comment on any aspect of this proposed rule.

1. In section D of this preamble, EPA has presented a discussion of how EPA determines State compliance with section 303( c)( 2)( 9). The process described has been the Agency's general practice since the beginning of the water quality standards program, although the requirements specific to toxics criteria have evolved over the years. Briefly stated, EPA's ten Regional offices review the State adopted standards to ascertain compliance with the Clean Water Act using the information developed by the State and other relevant and available data and information.

For compliance with section 303( c)( 2)( B), EPA's focus in many cases was on the process the State used to assemble the criteria for those priority toxic pollutants which could reasonably be expected to interfere with the State's designated uses. For example, EPA's review of individual State water quality standards had to balance a need for national consistency with the need to implement the CWA scheme that provides for State primacy and State specific approaches. If EPA had information on a toxic pollutant sufficient to satisfy the test that the pollutant can reasonably be expected to interfere with designated uses, and the State did not adopt sufficient, scientifically defensible criteria for that pollutant, EPA disapproved the State action as being inconsistent with Section 303( c)( 2)( B). Alternative approaches could have had either a narrower focus on fewer priority toxic pollutants ( for example, relying only on the results of the section 304( l) short list process) or might have been broader, ( for example, requiring most States to adopt criteria for the complete list of priority toxic pollutants addressed in EPA section 304( a) criteria recommendations). EPA solicits comment on whether the Agency's traditional review process should have been changed.

2. EPA's approach and rationale for deciding which criteria to propose for a State is discussed in section E of this Preamble. Briefly stated, EPA either: ( 1) Proposed to promulgate Federal criteria for all priority toxic pollutants not acceptably addressed by approved State criteria ( this approach is used for most States), or ( 2) proposed to promulgate Federal criteria only for specific priority pollutants for which State criteria are lacking or insufficient ( this approach is used for only a few States). EPA could have used other approaches and solicits public comment. For example, EPA could have relied totally on the State's own determination pursuant to section 304( l) and 305( b), or entirely on an Option 1 approach of promulgating all Federal criteria for all State waters.

3. This proposed rulemaking includes proposed minimum implementation factors for the criteria, such as flow conditions. As proposed, these factors are dependent on existing State rules but subject to base values which are those used in developing the criteria. EPA's revised TSD explains more fully the details of these base values. EPA could rely entirely on existing State rules or establish the proposed Federal rules.

4. The conditions under which States will be removed from the rule, either before or after final promulgation, are described in section E. 4 of this preamble. EPA could make the conditions for removing the applicability of the rule to a State more or less stringent. A difficult aspect of this issue is a definition of what the State must adopt for EPA to withdraw the applicability of its rule entirely. As currently stated, EPA's policy is that if the State's standards are judged to meet the requirements of the Act and thereby provide adequate environmental protection, EPA will withdraw the applicability of the Federal Rule as to that State. In the context of this proposal, the State would have to demonstrate that the criteria it adopted meet the statutory test of protecting the public health and would protect designated uses. State compliance could be by any one or a combination of the 3 options described in EPA's guidance. Once such a showing were made EPA would propose to withdraw the applicability of its rule entirely. However, if a State fails to make such a demonstration for all pollutants, partial withdrawals for certain pollutants could occur, leaving applicable parts of the Federal rule.

5. EPA must also decide whether it should pick a uniform cancer risk level of, for example, 10/ 6/, for all States included in a final rule, or whether different risk levels for different States are appropriate. EPA today proposes the human health criteria at a cancer risk level of 10/ 6/ because such a risk level is conservative for the general population and in the generally applied risk range. However, as noted in section F. 5., EPA has approved human health risk levels of 10/ 5/ in 10 States, and for some criteria and uses risk levels of 10/ 4/. EPA's review of the explanations provided by the States supporting State adopted risk levels of less than 10 / 5/ focuses on public participation and the supportability of the risk factors included in the State's analysis.

While today's proposed action is predicated on a 10/ 6/ risk level for carcinogens, another option that the public should consider in responding to this rule is the application of the proposed criteria at a 10/ 5/ risk level. EPA's rationale for proposing at a 10/ 6/ risk level was articulated earlier in the preamble. However, there are several arguments to support a less protective 10/ 5/ level. The model used to calculate the criteria for carcinogens is a conservative one and has a very low probability of underestimating the potency of a carcinogen. As a result, a higher level of accepted risk as the endpoint for criteria calculations may be reasonable. For " Class C" carcinogens, i. e., those for which the data demonstrating oncogenicity in animal studies are most limited, a 10/ 5/ risk level is closer to the criteria values calculated as Rfds ( non cancer endpoints of toxicity) for these chemicals. Use of RfDs reduces the likelihood that EPA is over regulating chemicals of less definitive cancer potency. A 10/ 5/ risk is within the range of accepted risks for other major EPA rulemakings which aim to protect the general public, such as national drinking water standards.

Similarly, EPA must decide what a State must adopt in the way of a risk level for EPA to withdraw a final rule. The question to be addressed is whether EPA can accept less stringent risk levels ( applied statewide; by individual chemicals, or by geographical sub area) than contained in EPA's final rule if such less stringent risk levels were adopted following State administrative procedures and adequately supported by the administrative record.

6. Today's proposed rulemaking includes an Agency proposal to establish criteria for only those EPA priority toxic pollutant criteria which are based on toxic effects. The Agency could include other section 304( a) priority toxic pollutant criteria recommendations which are based on organoleptic ( i. e., taste and odor) effects. The logic would be that the congressional reference to " toxic pollutants" in section 303( c)( 2)( B) was the generic list of 126 priority toxic pollutants and EPA should include all such criteria developed for these pollutants rather than just those based on toxicity. Organoleptic effects cause taste and odor problems in drinking water which may increase treatment costs or the selection by the public of alternative but less protective sources of drinking water; and may cause tainting or off flavors in fish flesh and other edible aquatic life reducing their marketability, thus diminishing the recreational and resource value of the water. EPA believes that because the Section 303( c)( 2)( B) focuses on toxicity of the priority toxic pollutants, EPA's proposal should likewise focus on toxicity.

7. EPA also invites public comment on the merits of promulgating a translator procedure ( that could support derivation of new or revised chemical specific criteria for those priority toxic pollutants for which EPA has not issued section 304( a) criteria guidance) for States in this rule to enhance State and EPA implementation of section 303 ( c)( 2)( B). Such a procedure would supplement the specific numeric criteria included in this proposal. The rationale for, and specifics of, such an approach are described below. As discussed in previous sections of this preamble, CWA section 303( c)( 2)( B) represents a clear congressional mandate for State adoption of chemical specific numeric criteria for priority toxic pollutants where EPA has issued section 304( a) criteria guidance. However, where no such criteria exist, section 303( c)( 2)( B) went on to direct States that, " * * * Where such numerical criteria are not available, whenever a State reviews water quality standards * * * or revises or adopts new standards * * *, such State shall adopt criteria based on biological monitoring or assessment methods * * *.

EPA's December 1988 national guidance provided States with three options for satisfying the chemical specific criteria requirements. Option 3 of the guidance allows States to adopt and apply translator procedures. As described in section B 3 of this preamble, such translator procedures are defined as the methods, equations, and protocols by which a State calculates derived chemical specific numeric criteria for priority toxic pollutants to ensure that the State's narrative toxics criterion is fully satisfied.

There are several alternative approaches for establishing a translator procedure. All approaches would utilize EPA's criteria guidelines ( i. e., for aquatic life and human health as described in section F. 1. of this preamble) as the basis for deriving chemical specific criteria. They could also require EPA to periodically issue an updated list of derived numeric criteria and notice the availability of the list in the Federal Register.

One alternative would be to promulgate a mechanism for State usage only for the pollutants where EPA has not issued a section 304 ( a) criteria guidance document.

Another alternative would be to allow criteria revisions in specific situations where EPA determines that a revised criterion is necessary. For example, if EPA issued a final revised estimate of the cancer potency slope of a priority toxic pollutant ( i. e., by adding it to IRIS), such cancer slopes would be available for use in deriving new human health criteria for that pollutant following the translator procedure. Another example would be situations where additional data on the toxicity of a pollutant to aquatic life becomes available such that the minimum database requirements in the EPA criteria guidelines are satisfied. In such situations, the data could be applied to the translator procedure to derive new or revised aquatic life criteria more rapidly than the current method of proposing for comment and then publishing a final section 304( a) recommendation for subsequent consideration by States. This alternative would apply to criteria for both aquatic life and human health protection and could apply to pollutants for which a section 304( a) criteria recommendation exists or to those pollutants where no such recommendation exists.

A third approach would limit the applicability of the translator procedure to the priority toxic pollutants for which numeric criteria are contained in today's proposed rulemaking. Under this alternative, criteria could not be derived for pollutants without a section 304( a) criteria recommendation using the translator procedure, even where: ( 1) Formal Agency estimates of the parameters necessary to support derivation are issued, or ( 2) the data necessary to satisfy the minimum database requirements become available.

A final alternative providing only limited flexibility would be to limit use of the translator procedure to human health criteria where the Agency issues a final revised risk assessment for the parameter in IRIS. Such IRIS estimates are subject to extensive intra Agency review. This alternative would limit revisions to situations where EPA makes a formal determination that a revised human health risk assessment is appropriate.

The Agency invites public comment on the environmental, programmatic and legal aspects of including a promulgation of a criteria translator mechanism for each State in the final issuance of this rulemaking. Comment is also invited on the scope and details of such an approach as described above.

8. EPA solicits comment on the section 304( a) assessment methodology ( cancer and non cancer) used to derive human health criteria for section 307( a) priority toxic pollutants. This methodology is discussed in section F of the Preamble but is derived in the criteria methodology published in the Federal Register on November 26, 1980 ( 45 FR 79347). For example, EPA has included proposed criteria for 3 PAHs ( acenaphthylene, benzo( ghi) perylene and phenanthrene). The included criteria treat these PAHs as carcinogens and are based on data for benzo( a) pyrene. The section 304( a) criteria methodology does not distinguish between classes of carcinogens and allows the use of closely related chemicals of similar structure to carry the same criteria recommendation. This methodology is basic to the development of the human health criteria proposed today.

I. Executive Order 12291 Executive Order 12291 requires EPA and other agencies to perform regulatory impact analyses for major regulations. Major regulations are those that impose an annual cost to the economy of $ 100 million or more, or meet other criteria. This is a major regulation, however, a regulatory impact analyses has been waived by the Office of Management and Budget for this proposal for the reasons discussed below.

This rulemaking establishes a legal minimum standard where States have failed to comply with the statutory mandate to adopt numeric criteria for toxic pollutants. The impacts to dischargers are no different than what would occur if States had acted to adopt their own standards. There will be a cost to dischargers for complying with these proposed new standards as the standards are translated into specific NPDES permit limits for individual dischargers. However, for reasons discussed in more detail below, a meaningful cost estimate is difficult to develop. The increased costs incurred will depend upon the type and amount of pollutants discharged and the extent to which additional treatment needs to be installed beyond that which is required to meet the generally applicable technology based limit regulations. As discussed earlier in the Preamble, the control of toxic pollutants is expected to provide societal benefits by reducing risk to human health and to reduce ecological impacts on aquatic life.

The general impacts on point source dischargers, publicly owned treatment works ( POTWs) and nonpoint sources may be described. By establishing new goals for a waterbody, the addition of criteria for toxic pollutants into State water quality standards will affect the wasteload allocations developed for each waterbody segment to the extent the pollutant is actually discharged into the stream. If the pollutant is not present in the wastestream, the addition of criteria has no impact. Revised wasteload allocations may result in adjustments to individual NPDES permit limits for point source dischargers which could result in increased incremental treatment costs required to meet the revised water quality standards. These costs will vary depending on the types of treatment involved, the number and kind of pollutant( s) being treated, and the controls necessary to meet the technologically based effluent limits for a given industry.

Compliance costs for indirect industrial dischargers will be reflected in increased incremental costs for POTWs assuming that industrial sources are the primary source of toxics discharged by POTWs and that the incremental treatment costs incurred by POTWs will be passed along to their industrial dischargers. Possible areas where the addition of criteria for toxic pollutants into State standards may have a cost impact include: ( 1) POTW expansion, ( 2) operational changes, and ( 3) increased operator training costs.

Increased costs may also be incurred by nonpoint sources of toxic pollutants to the extent that best management practices need to be modified to reflect the revised standards. Although there is no comparable Federal permit program for nonpoint sources as there is to control point source discharges, there are existing State regulatory programs to control nonpoint sources.

Monitoring programs to generate information on the existing quality of water and the kinds and amount of pollutants being discharged are likely to be affected by this proposed rulemaking. However, the addition of criteria for toxic pollutants into State standards does not require the State to engage in a program to monitor for all such pollutants unless there is some reasonable expectation that the pollutants are manufactured or actually used in the State with the likelihood that they will be discharged into surface waters.

While recognizing that the application of criteria for toxic pollutants will result in increased treatment costs and that such costs are appropriately considered in several areas of the standards to permits process, it is important to consider the difficulties and the large potential uncertainties involved in developing meaningful cost estimates for purposes of this proposed rulemaking. The development of compliance cost estimates would require numerous assumptions about pollutant loadings, impacts of technology based regulations on loadings, combinations of pollutants handled by a given treatment approach, the costs of each treatment train and the variables for each pollutant in each waterbody in each State. There are many sources of uncertainty in making these assumptions, and the resulting estimates could contain such significant estimation errors that the figures would have questionable value.

This proposed rule, including the above determination, has been reviewed by the Office of Management and Budget. Any written comments from OMB to EPA and any EPA response to those comments are included in the public record and are available for inspection.

J. Regulatory Flexibility Act The Regulatory Flexibility Act ( 5 U. S. C. 601 et seq., Pub. L. 96 354) requires EPA to assess whether its regulations create a disproportionate effect on small entities. According to the provisions of the Act, EPA must prepare an initial regulatory flexibility analysis for all proposed regulations that have a significant impact on a substantial number of small entities. There will be a cost to dischargers for complying with these standards as they are translated into permit limits for individual dischargers. However, for the reasons discussed in the previous section, a meaningful estimate of the total cost or impact on small entities cannot be meaningfully computed.

This proposed regulation fills a regulatory void left by States not fully complying with the statute; thus, the impact on small entities is not different than what would have occurred if States had acted to adopt standards. In addition, the water quality standards regulation provides several means ( such as adjusting designated uses, setting site specific criteria, or granting variances) to consider costs and adjust standards to account for the impacts on dischargers.

K. Paperwork Reduction Act The information collection requirements associated with this proposed rule have been submitted for approval to the Office of Management and Budget ( OMB) under the Paperwork Reduction Act, 44 U. S. C. 3501 et seq. An Information Collection Request ( ICR) document has been prepared by EPA ( ICR No. 0988.04) and a copy may be obtained from Sandy Farmer, Information Policy Branch; EPA; 401 M St., SW. ( PM 223Y); Washington, DC 20460 or by calling ( 202) 382 2740.

Public reporting burden for this collection of information is estimated to average 745 hours per respondent, including time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection information.

Send comments regarding the burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Chief, Information Policy Branch, PM 223Y, U. S. EPA, 401 M St., SW., Washington, DC 20460; and to the Office of Information and Regulatory Affairs; Office of Management and Budget, Washington, DC 20503, marked " Attention: Desk Officer for EPA." The final rule will respond to any OMB or public comments on the information collection requirements contained in this proposal.

List of Subjects Water quality standards, Toxic pollutants.

Dated: November 6, 1991.

William K. Reilly, Administrator.

For the reasons set out in the preamble, part 131 of title 40 of the Code of Federal Regulations is proposed to be amended as follows:

PART 131 WATER QUALITY STANDARDS 1. The authority citation for part 131 continues to read as follows:

Authority: Clean Water Act, Pub. L. 92 500, as amended; 33 U. S. C. 1251 et seq.

2. Section 131.36 is added to subpart D to read as follows:

Sec. 131.36 Toxics criteria for those states not complying with Clean Water Act section 303( c)( 2)( B)

( a) Scope. This section is not a general promulgation of the section 304( a) criteria for priority toxic pollutants but is restricted to specific pollutants in specific States.

( b) EPA's Section 304( a) Criteria for Priority Toxic Pollutants B A Freshwater Criterion Criterion maximum continuous concentration concentration d ( micro g/ L) d ( micro g/ L) (#) Compound CAS No. B1 B2 1 Antimony 7440360 2 Arsenic 7440382 360 190 3 Beryllium 7440417 4 Cadmium 7440439 3.9 e 1.1 e 5a Chromium ( III) 16065831 1700 e 210 e b Chromium ( VI) 18540299 16 11 6 Copper 7440508 18 e 12 e 7 Lead 7439921 82 e 3.2 e 8 Mercury 7439976 2.4 0.012 i 9 Nickel 7440020 1400 e 160 e 10 Selenium 7782492 20 5 11 Silver 7440224 4.1 e 12 Thallium 7440280 13 Zinc 7440666 120 e 110 e 14 Cyanide 57125 22 5.2 15 Asbestos 1332214 7,000,000 fibers/ L k 16 2,3,7,8 TCDD ( Dioxin) 1746016 17 Acrolein 107028 18 Acrylonitrile 107131 19 Benzene 71432 20 Bromoform 75252 21 Carbon Tetrachloride 56235 22 Chlorobenzene 108907 23 Chlorodibromomethane 124481 24 Chloroethane 75003 25 2 Chloroethylvinyl Ether 110758 26 Chloroform 67663 27 Dichlorobromomethane 75274 28 1,1 Dichloroethane 75343 29 1,2 Dichloroethane 107062 30 1,1 Dichloroethylene 75354 31 1,2 Dichloropropane 78875 32 1,3 Dichloropropylene 542756 33 Ethylbenzene 100414 34 Methyl Bromide 74839 35 Methyl Chloride 74873 36 Methylene Chloride 75092 37 1,1,2,2 Tetrachloroethane 79345 38 Tetrachloroethylene 127184 39 Toluene 108883 40 1,2 Trans Dichloroethylene 156605 41 1,1,1 Trichloroethane 71556 42 1,1,2 Trichloroethane 79005 43 Trichloroethylene 79016 44 Vinyl Chloride 75014 45 2 Chlorophenol 95578 46 2,4 Dichlorophenol 120832 47 2,4 Dimethylphenol 105679 48 2 Methyl 4,6 Dinitrophenol 534521 49 2,4 Dinitrophenol 51285 50 2 Nitrophenol 88755 51 4 Nitrophenol 100027 52 3 Methyl 4 Chlorophenol 59507 53 Pentachlorophenol 87865 20 f 13 f 54 Phenol 108952 55 2,4,6 Trichlorophenol 88062 56 Acenaphthene 83329 57 Acenaphthylene 208968 58 Anthracene 120127 59 Benzidine 92875 60 Benzo( a) Anthracene 56553 61 Benzo( a) Pyrene 50328 62 Benzo( b) Fluoranthene 205992 63 Benzo( ghi) Perylene 191242 64 Benzo( k) Fluoranthene 207089 65 Bis( 2 Chloroethoxy) Methane 111911 66 Bis( 2 Chloroethyl) Ether 111444 67 Bis( 2 Chloroisopropyl) Ether 108601 68 Bis( 2 Ethylhexyl) Phthalate 117817 69 4 Bromophenyl Phenyl Ether 101553 70 Butylbenzyl Phthalate 85687 71 2 Chloronaphthalene 91587 72 4 Chlorophenyl Phenyl Ether 7005723 73 Chrysene 218019 74 Dibenzo( a, h) Anthracene 53703 75 1,2 Dichlorobenzene 95501 76 1,3 Dichlorobenzene 541731 77 1,4 Dichlorobenzene 106467 78 3,3' Dichlorobenzidine 91941 79 Diethyl Phthalate 84662 80 Dimethyl Phthalate 131113 81 Di n Butyl Phthalate 84742 82 2,4 Dinitrotoluene 121142 83 2,6 Dinitrotoluene 606202 84 Di n Octyl Phthalate 117840 85 1,2 Diphenylhydrazine 122667 86 Fluoranthene 206440 87 Fluorene 86737 88 Hexachlorobenzene 118741 89 Hexachlorobutadiene 87683 90 Hexachlorocyclopentadiene 77474 91 Hexachloroethane 67721 92 Indeno( 1,2,3 cd) Pyrene 193395 93 Isophorone 78591 94 Naphthalene 91203 95 Nitrobenzene 98953 96 N Nitrosodimethylamine 62759 97 N Nitrosodi n Propylamine 621647 98 N Nitrosodiphenylamine 86306 99 Phenanthrene 85018 100 Pyrene 129000 101 1,2,4 Trichlorobenzene 120821 102 Aldrin 309002 3 g 103 alpha BHC 319846 104 beta BHC 319857 105 gamma BHC 58899 2 g 0.08 g 106 delta BHC 319868 107 Chlordane 57749 2.4 g 0.0043 g 108 4 4' DDT 50293 1.1 g 0.001 g 109 4,4' DDE 72559 110 4,4' DDD 72548 111 Dieldrin 60571 2.5 g 0.0019 g 112 alpha Endosulfan 959988 0.22 g 0.056 g 113 beta Endosulfan 33213659 0.22 g 0.056 g 114 Endosulfan Sulfate 1031078 115 Endrin 72208 0.18 g 0.0023 g 116 Endrin Aldehyde 7421934 117 Heptachlor 76448 0.52 g 0.0038 g 118 Heptachlor Epoxide 1024573 0.52 g 0.0038 g 119 PCB 1242 53469219 0.014 g 120 PCB 1254 11097691 0.014 g 121 PCB 1221 11104282 0.014 g 122 PCB 1232 11141165 0.014 g 123 PCB 1248 12672296 0.014 g 124 PCB 1260 11096825 0.014 g 125 PCB 1016 12674112 0.014 g 126 Toxaphene 8001352 0.73 0.0002 Total No. of Criteria ( h) = 24 29 ( ... Table continues... ) C A Saltwater Criterion Criterion maximum continuous concentration concentration d ( micro g/ L) d ( micro g/ L) (#) Compound C1 C2 1 Antimony 2 Arsenic 69 36 3 Beryllium 4 Cadmium 43 9.3 5a Chromium ( III) b Chromium ( VI) 1100 50 6 Copper 2.9 2.9 7 Lead 220 8.5 8 Mercury 2.1 0.025 i 9 Nickel 75 8.3 10 Selenium 300 71 11 Silver 2.3 12 Thallium 13 Zinc 95 86 14 Cyanide 1 1 15 Asbestos 7,000,000 fibers/ L k 16 2,3,7,8 TCDD ( Dioxin) 17 Acrolein 18 Acrylonitrile 19 Benzene 20 Bromoform 21 Carbon Tetrachloride 22 Chlorobenzene 23 Chlorodibromomethane 24 Chloroethane 25 2 Chloroethylvinyl Ether 26 Chloroform 27 Dichlorobromomethane 28 1,1 Dichloroethane 29 1,2 Dichloroethane 30 1,1 Dichloroethylene 31 1,2 Dichloropropane 32 1,3 Dichloropropylene 33 Ethylbenzene 34 Methyl Bromide 35 Methyl Chloride 36 Methylene Chloride 37 1,1,2,2 Tetrachloroethane 38 Tetrachloroethylene 39 Toluene 40 1,2 Trans Dichloroethylene 41 1,1,1 Trichloroethane 42 1,1,2 Trichloroethane 43 Trichloroethylene 44 Vinyl Chloride 45 2 Chlorophenol 46 2,4 Dichlorophenol 47 2,4 Dimethylphenol 48 2 Methyl 4,6 Dinitrophenol 49 2,4 Dinitrophenol 50 2 Nitrophenol 51 4 Nitrophenol 52 3 Methyl 4 Chlorophenol 53 Pentachlorophenol 13 7.9 54 Phenol 55 2,4,6 Trichlorophenol 56 Acenaphthene 57 Acenaphthylene 58 Anthracene 59 Benzidine 60 Benzo( a) Anthracene 61 Benzo( a) Pyrene 62 Benzo( b) Fluoranthene 63 Benzo( ghi) Perylene 64 Benzo( k) Fluoranthene 65 Bis( 2 Chloroethoxy) Methane 66 Bis( 2 Chloroethyl) Ether 67 Bis( 2 Chloroisopropyl) Ether 68 Bis( 2 Ethylhexyl) Phthalate 69 4 Bromophenyl Phenyl Ether 70 Butylbenzyl Phthalate 71 2 Chloronaphthalene 72 4 Chlorophenyl Phenyl Ether 73 Chrysene 74 Dibenzo( a, h) Anthracene 75 1,2 Dichlorobenzene 76 1,3 Dichlorobenzene 77 1,4 Dichlorobenzene 78 3,3' Dichlorobenzidine 79 Diethyl Phthalate 80 Dimethyl Phthalate 81 Di n Butyl Phthalate 82 2,4 Dinitrotoluene 83 2,6 Dinitrotoluene 84 Di n Octyl Phthalate 85 1,2 Diphenylhydrazine 86 Fluoranthene 87 Fluorene 88 Hexachlorobenzene 89 Hexachlorobutadiene 90 Hexachlorocyclopentadiene 91 Hexachloroethane 92 Indeno( 1,2,3 cd) Pyrene 93 Isophorone 94 Naphthalene 95 Nitrobenzene 96 N Nitrosodimethylamine 97 N Nitrosodi n Propylamine 98 N Nitrosodiphenylamine 99 Phenanthrene 100 Pyrene 101 1,2,4 Trichlorobenzene 102 Aldrin 1.3 g 103 alpha BHC 104 beta BHC 105 gamma BHC 0.16 g 106 delta BHC 107 Chlordane 0.09 g 0.004 g 108 4 4' DDT 0.13 g 0.001 g 109 4,4' DDE 110 4,4' DDD 111 Dieldrin 0.71 g 0.0019 g 112 alpha Endosulfan 0.034 g 0.0087 g 113 beta Endosulfan 0.034 g 0.0087 g 114 Endosulfan Sulfate 115 Endrin 0.037 g 0.0023 g 116 Endrin Aldehyde 117 Heptachlor 0.053 g 0.0036 g 118 Heptachlor Epoxide 0.053 g 0.0036 g 119 PCB 1242 0.03 g 120 PCB 1254 0.03 g 121 PCB 1221 0.03 g 122 PCB 1232 0.03 g 123 PCB 1248 0.03 g 124 PCB 1260 0.03 g 125 PCB 1016 0.03 g 126 Toxaphene 0.21 0.0002 Total No. of Criteria ( h) = 33 27 ( ... Table continues... ) D Human health ( 10 6 risk for carcinogens) A For consumption of: Water and organisms Organisms ( micro g/ L) only ( micro (#) Compound D1 g/ L) D2 1 Antimony 14 a 4300 a 2 Arsenic 0.018 bc 0.14 bc 3 Beryllium 0.0077 ac 0.13 ac 4 Cadmium 16 170 aj 5a Chromium ( III) 33000 a 670000 a b Chromium ( VI) 170 a 3400 a 6 Copper ( 1300) b 7 Lead 50 8 Mercury 0.14 0.15 9 Nickel 610 a 4600 a 10 Selenium 100 b 6800 bj 11 Silver 105 a 65000 aj 12 Thallium 1.7 a 6.3 a 13 Zinc 14 Cyanide 700 a 220000 aj 15 Asbestos 7,000,000 fibers/ L k 16 2,3,7,8 TCDD ( Dioxin) 0.000000013 c 0.000000014 c 17 Acrolein 320 780 18 Acrylonitrile 0.059 ac 0.66 ac 19 Benzene 1.2 ac 71 ac 20 Bromoform 4.3 ac 360 ac 21 Carbon Tetrachloride 0.25 ac 4.4 ac 22 Chlorobenzene 680 a 21000 aj 23 Chlorodibromomethane 0.41 ac 34 ac 24 Chloroethane 25 2 Chloroethylvinyl Ether 26 Chloroform 5.7 ac 470 ac 27 Dichlorobromomethane 0.27 ac 22 ac 28 1,1 Dichloroethane 29 1,2 Dichloroethane 0.38 ac 99 ac 30 1,1 Dichloroethylene 0.057 ac 3.2 ac 31 1,2 Dichloropropane ( 0.52) kc ( 39) kc 32 1,3 Dichloropropylene 10 a 1700 a 33 Ethylbenzene 3100 a 29000 a 34 Methyl Bromide 48 a 4000 a 35 Methyl Chloride 5.7 ac 470 ac 36 Methylene Chloride 4.7 ac 1600 ac 37 1,1,2,2 Tetrachloroethane 0.17 ac 11 ac 38 Tetrachloroethylene 0.8 c 8.85 c 39 Toluene 6800 a 200000 a 40 1,2 Trans Dichloroethylene ( 700) a ( 140000) a 41 1,1,1 Trichloroethane 3100 a ( 170000) a 42 1,1,2 Trichloroethane 0.60 ac 42 ac 43 Trichloroethylene 2.7 c 81 c 44 Vinyl Chloride 2 c 525 c 45 2 Chlorophenol ( 120) a ( 400) a 46 2,4 Dichlorophenol 93 a 790 aj 47 2,4 Dimethylphenol ( 540) a ( 2300) a 48 2 Methyl 4,6 Dinitrophenol 13.4 765 49 2,4 Dinitrophenol 70 a 14000 a 50 2 Nitrophenol 51 4 Nitrophenol 52 3 Methyl 4 Chlorophenol 53 Pentachlorophenol 0.28 ac 8.2 acj 54 Phenol 21000 a 4600000 aj 55 2,4,6 Trichlorophenol 2.1 ac 6.5 ac 56 Acenaphthene ( 1200) a ( 2700) a 57 Acenaphthylene 0.0028 c 0.031 c 58 Anthracene 9600 a 110000 a 59 Benzidine 0.00012 ac 0.00054 ac 60 Benzo( a) Anthracene 0.0028 c 0.031 c 61 Benzo( a) Pyrene 0.0028 c 0.031 c 62 Benzo( b) Fluoranthene 0.0028 c 0.031 c 63 Benzo( ghi) Perylene 0.0028 c 0.031 c 64 Benzo( k) Fluoranthene 0.0028 c 0.031 c 65 Bis( 2 Chloroethoxy) Methane 66 Bis( 2 Chloroethyl) Ether 0.031 ac 1.4 ac 67 Bis( 2 Chloroisopropyl) Ether 1400 a 170000 a 68 Bis( 2 Ethylhexyl) Phthalate 1.8 ac 5.9 ac 69 4 Bromophenyl Phenyl Ether 70 Butylbenzyl Phthalate ( 3000) a ( 5200) a 71 2 Chloronaphthalene ( 1700) a ( 4300) a 72 4 Chlorophenyl Phenyl Ether 73 Chrysene 0.0028 c 0.031 c 74 Dibenzo( a, h) Anthracene 0.0028 c 0.031 c 75 1,2 Dichlorobenzene 2700 a 17000 a 76 1,3 Dichlorobenzene 400 2600 77 1,4 Dichlorobenzene 400 2600 78 3,3' Dichlorobenzidine 0.04 ac 0.077 ac 79 Diethyl Phthalate 23000 a 120000 a 80 Dimethyl Phthalate 313000 2900000 81 Di n Butyl Phthalate 2700 a 12000 a 82 2,4 Dinitrotoluene 0.11 c 9.1 c 83 2,6 Dinitrotoluene 84 Di n Octyl Phthalate 85 1,2 Diphenylhydrazine 0.040 ac 0.54 ac 86 Fluoranthene 300 a 370 a 87 Fluorene 1300 a 14000 a 88 Hexachlorobenzene 0.00075 ac 0.00077 ac 89 Hexachlorobutadiene 0.44 ac 50 ac 90 Hexachlorocyclopentadiene 240 a 17000 aj 91 Hexachloroethane 1.9 ac 8.9 ac 92 Indeno( 1,2,3 cd) Pyrene 0.0028 c 0.031 c 93 Isophorone 8.4 ac 600 ac 94 Naphthalene 95 Nitrobenzene 17 a 1900 aj 96 N Nitrosodimethylamine 0.00069 ac 8.1 ac 97 N Nitrosodi n Propylamine ( 0.005) ac ( 1.4) ac 98 N Nitrosodiphenylamine 5.0 ac 16 ac 99 Phenanthrene 0.0028 c 0.031 c 100 Pyrene 960 a 11000 a 101 1,2,4 Trichlorobenzene 102 Aldrin 0.00013 ac 0.00014 ac 103 alpha BHC 0.0039 ac 0.013 ac 104 beta BHC 0.014 ac 0.046 ac 105 gamma BHC 0.019 c 0.063 c 106 delta BHC 107 Chlordane 0.00057 ac 0.00059 ac 108 4 4' DDT 0.00059 ac 0.00059 ac 109 4,4' DDE 0.00059 ac 0.00059 ac 110 4,4' DDD 0.00083 ac 0.00084 ac 111 Dieldrin 0.00014 ac 0.00014 ac 112 alpha Endosulfan 0.93 a 2.0 a 113 beta Endosulfan 0.93 a 2.0 a 114 Endosulfan Sulfate 0.93 a 2.0 a 115 Endrin 0.76 a 0.81 aj 116 Endrin Aldehyde 0.76 a 0.81 aj 117 Heptachlor 0.00021 ac 0.00021 ac 118 Heptachlor Epoxide 0.00010 ac 0.00011 ac 119 PCB 1242 0.000044 ac 0.000045 ac 120 PCB 1254 0.000044 ac 0.000045 ac 121 PCB 1221 0.000044 ac 0.000045 ac 122 PCB 1232 0.000044 ac 0.000045 ac 123 PCB 1248 0.000044 ac 0.000045 ac 124 PCB 1260 0.000044 ac 0.000045 ac 125 PCB 1016 0.000044 ac 0.000045 ac 126 Toxaphene 0.00073 ac 0.00075 ac Total No. of Criteria ( h) = 103 102 Footnotes: a. Criteria revised to reflect current agency q1* or RfD, as contained in the Integrated Risk Information System ( IRIS). The fish tissue bioconcentration factor ( BCF) from the 1980 criteria documents was retained in all cases. Values in parentheses indicate that no health based criteria appeared in the 1980 documents. The criteria in parentheses are not being proposed today but are presented as notice for inclusion in future state triennial reviews.

b. EPA in the Office of Research and Development's Environmental Criteria and Assessment Office prepared draft updates of criteria documents for arsenic, copper and selenium which are used instead of IRIS for this rulemaking. Each document was entitled as an " Addendum" to the prior criteria documents. These documents are available in the record for this proceeding.

c. Criteria based on carcinogenicity ( 10 6 risk).

d. Criteria Maximum Concentration= the highest concentration of a pollutant to which aquatic life can be exposed for a short period of time ( 1 hour average) without deleterious effects.

Criteria Continuous Concentration= the highest concentration of a pollutant to which aquatic life can be exposed for an extended period of time ( 4 days) without deleterious effects.

micro g/ L= micrograms per liter e. Freshwater aquatic life criteria for these metals are expressed as a function of total hardness ( mg/ L), as follows ( where exp represents the base e exponential function). ( Values displayed above in the matrix correspond to a total hardness of 100 mg/ L.)

CCC= exp[ mC CMC= exp[ mA( ln( hardness)) ( ln( hardness)) + bA] + bC] ma bA mC bC Cadmium 1.128  3.828 0.7852  3.490 Copper 0.9422  1.464 0.8545  1.465 Chromium ( III) 0.8190 3.688 0.8190 1.561 Lead 1.273  1.460 1.273  4.705 Nickel 0.8460 3.3612 0.8460 1.1645 Silver 1.72  6.52 Zinc 0.8473 0.8604 0.8473 0.7614 f. Freshwater aquatic life criteria for pentachlorophenol are expressed as a function of pH, and are calculated as follows. ( Values displayed above in the matrix correspond to a pH of 7.8.) CMC= exp( 1.005( pH) 4.830) CCC= exp( 1.005( pH) 5.290) g. Aquatic life criteria for these compounds were issued in 1980 utilizing the 1980 Guidelines for criteria development. The acute values shown are final acute values ( FAV). According to the 1980 Guidelines, the acute values were intended to be interpreted as instantaneous maximum values, and the chronic values shown were interpreted as 24 hour average values. EPA has not updated these criteria pursuant to the 1985 Guidelines. However, as an approximation, dividing the final acute values in columns B1 and C1 by 2 yields a Criterion Maximum Concentration. No numeric changes are required for columns B2 and C2, and EPA suggests using these values directly as Criterion Continuous Concentration.

h. These totals simply sum the criteria in each column. For aquatic life, there are 30 priority toxic pollutants with some type of freshwater or saltwater, acute or chronic criteria proposed. For human health, there are 102 priority toxic pollutants with either " water + fish" or " fish only" criteria proposed. Note that these totals count chromium as one pollutant even though EPA has developed criteria based on two valence states. In the matrix, EPA has assigned numbers 5a and 5b to the proposed criteria for chromium to reflect the fact that the list of 126 priority toxic pollutants includes only a single listing for chromium. Criteria enclosed in parentheses are also not included in the totals.

i. Applies to methyl mercury. j. No criteria for protection of human health from consumption of aquatic organisms ( excluding water) was presented in the 1980 criteria document or in the 1986 Quality Criteria for Water. Nevertheless, the criterion value has not been placed in parentheses, because sufficient information was presented in the 1980 document to allow a calculation of a criterion, even though the results of such a calculation were not shown in the document.

k. The criterion for asbestos is the MCL ( 56 FR 3526, January 30, 1991). The criteria for 1,2 dichloropropane have been derived using MCL ( 56 FR 3526, January 30, 1991).

General notes: ( 1) This chart lists all of EPA's priority toxic pollutants whether or not criteria recommendations are available. Blank spaces indicate the absence of criteria recommendations. Because of variations in chemical nomenclature systems, this listing of toxic pollutants does not duplicate the listing in appendix A of 40 CFR part 423. EPA has added the Chemical Abstracts Service ( CAS) registry numbers, which provide a unique identification for each chemical.

( 2) The following chemicals have organoleptic based criteria recommendations that are not included on this chart ( for reasons which are discussed in the preamble): copper, zinc, chlorobenzene, 2 chlorophenol, 2,4 dichlorophenol, acenaphthene, 2,4 dimethylphenol, 3 methyl 4 chlorophenol, hexachlorocyclopentadiene, pentachlorophenol, phenol ( 3) For purposes of this rulemaking, freshwater criteria apply at salinity levels equal to or less than 1 part per thousand ( ppt); saltwater criteria apply at salinity levels equal to or greater than 10 ppt; for waters with salinity between 1 and 10 ppt, the applicable criteria are the more stringent of the freshwater or saltwater criteria.

( c) Applicability. ( 1) The criteria in paragraph ( b) of this section apply to the States' designated uses cited in paragraph ( d) of this section and supersede any criteria adopted by the State, except when State regulations contain criteria which are more stringent for a particular use in which case the State's criteria will continue to apply; ( 2) The criteria established in this section are subject to the State's general rules of applicability in the same way and to the same extent as are the other numeric toxics criteria when applied to the same use classifications including mixing zones, and low flow values below which numeric standards can be exceeded in flowing fresh waters, but only if these State general policies have been reviewed and approved previously by EPA after November 8, 1983.

( i) For all waters with approved EPA mixing zone regulations or implementation procedures, the criteria apply at the appropriate locations within or at the boundary of the mixing zones; otherwise the criteria apply throughout the waterbody including at the end of any discharge pipe, canal or other discharge point.

( ii) A State shall not use a low flow value below which numeric standards can be exceeded that is less stringent than the following for waters suitable for the establishment of low flow return frequencies ( i. e., streams and rivers):

Aquatic Life acute criteria ( CMC); I Q 10 or I B 3 chronic criteria ( CCC); 7 Q 10 or 4 B 3 Human Health non carcinogens; 30 Q 5 carcinogens; harmonic mean flow where: CMC criteria maximum concentration= the water quality criteria to protect against acute effects in aquatic life and is the highest instream concentration of a priority toxic pollutant consisting of a one hour average not to be exceeded more than once every three years on the average.

CCC criteria continuous concentration= the water quality criteria to protect against chronic effects in aquatic life is the highest instream concentration of a priority toxic pollutant consisting of a 4 day average not to be exceeded more than once every three years on the average. 1 Q 10 is the lowest one day flow with an average recurrence frequency of once in 10 years determined hydrologically; 1 B 3 is biologically based and indicates an allowable exceedence of once every 3 years. It is determined by EPA's computerized method ( DFLOW model); 7 Q 10 is the lowest average 7 consecutive day low flow with an average recurrence frequency of once in 10 years determined hydrologically: 4 B 3 is biologically based and indicates an allowable exceedence for 4 consecutive days once every 3 years. It is determined by EPA's computerized method ( DFLOW model); 30 Q 5 is the lowest average 30 consecutive day low flow with an average recurrence frequency of once in 5 years determined hydrologically and, the harmonic mean flow is a long term mean flow value calculated by dividing the number of daily flows analyzed by the sum of the reciprocals of those daily flows.

( iii) If a State does not have such a low flow value for numeric standards compliance, then none shall apply and the criteria included in paragraph ( d) of this section herein apply at all flows.

( 3) The aquatic life criteria in the matrix in paragraph ( b) of this section apply as follows: ( i) For waters in which the salinity is equal to or less than 1 part per thousand, the applicable criteria are the freshwater criteria in Column B.

( ii) For waters in which the salinity is equal to or greater than 10 parts per thousand, the applicable criteria are the saltwater criteria in Column C; ( iii) For waters in which the salinity is between 1 and 10 parts per thousand, the applicable criteria are the more stringent of the freshwater or saltwater criteria. However, the Regional Administrator may approve the use of alternative criteria if scientifically defensible information and data demonstrate that on a site specific basis the biology of the waterbody is dominated by freshwater aquatic life and that freshwater criteria are more appropriate; or conversely, the biology of the waterbody is dominated by saltwater aquatic life and that saltwater criteria are more appropriate.

( 4) Application of metals criteria. ( i) For purposes of calculating freshwater aquatic life criteria for metals from the equations in footnote ( e) in the criteria matrix in paragraph ( b) of this section, the minimum hardness allowed for use in those equations shall not be less than 25 mg/ l, as calcium carbonate, even if the actual ambient hardness is less than 25 mg/ l as calcium carbonate. The maximum hardness value for use in those equations shall not exceed 400 mg/ l as calcium carbonate, even if the actual ambient hardness is greater than 400 mg/ l as calcium carbonate.

( ii) The hardness values used shall be consistent with the design discharge conditions established in pararaph ( c)( 2) of this section for flows and mixing zones.

( d) Criteria for Specific Jurisdictions.( 1) Connecticut, Region 1 ( i) All waters assigned to the following use classifications in the " State of Connecticut Water Quality Standards" adopted pursuant to section 22a 426 of the Connecticut General Statutes are subject to the criteria in paragraph ( d)( 1)( ii) of this section, without exception:

II. 5.( A) Class AA Surface Waters II. 5.( B) Class A and SA Surface Waters II. 5.( C) Class B and SB Surface Waters ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 1)( i) of this section:

Use classification Applicable criteria Class AA; Class A; Class B waters Each of these classifications is where water supply use is designated assigned the criteria in: Column B( I) all. Column B( II) all. Column D( I) all. Class B waters where water supply use This classification is assigned the is not designated criteria in: Column B( I) all. Column B( II) all. Column D( II). Class SA; Class SB Each of these classifications is assigned the criteria in: Column C( I) all. Column C( ll) all. Column D ( II) all.

( 2) New Hampshire, Region 1 ( i) All waters assigned to the following use classifications in the New Hampshire Revised Statutes Annotated Chapter 149: 3 are subject to the criteria in paragraph ( d)( 2)( ii) of this section, without exception:

149: 3. I Class A 149: 3. II Class B 149: 3. III Class C ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( a)( i) of this section:

Use classification Applicable criteria Class A; Class B waters where water Each of these classifications is supply use is designated assigned the criteria in: Column D ( I)# 16. Class B waters where water supply use Column D( II)# 16. is not designated Class C ( 3) Rhode Island, Region 1 ( i) All waters assigned to the following use classifications in the Water Quality Regulations for Water Pollution Control adopted under chapters 46 12, 42 17.1, and 42 35 of the General Laws of Rhode Island are subject to the criteria in paragraph d( 3)( ii) of this section without exception: 6.21 Freshwater Class A Class B Class C 6.22 Saltwater Class SA Class SB Class SC ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 3)( i) of this section:

Use classification Applicable criteria Class A; Class B waters where water These classifications are assigned supply use is designated the criteria in: Column D ( I) all. Class B waters where water supply use Each of these classifications is is not designated Class C; Class SA; assigned the criteria in: Class SB; Class SC Column D ( II) all.

( 4) Vermont, Region 1 ( i) All waters assigned to the following use classifications in the Vermont Water Quality Standards adopted under the authority of the Vermont Water Pollution Control Act ( 10 V. S. A., Chapter 47) are subject to the criteria in paragraph ( d)( 4)( ii) of this section, without exception:

Class A Class B Class C ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 4)( i) of this section:

Use classification Applicable criteria Class A; Class B waters where water This classification is assigned the supply use is designated criteria in: Column B( I) all. Column B( II) all. Column D( I) all. Class B waters where water supply use These classifications are assigned is not designated; Class C the criteria in: Column B( I) all. Column B( II) all. Column D( II) all.

( 5) New Jersey, Region 2 ( i) All waters assigned to the following use classifications in the New Jersey Administrative Code ( N. J. A. C.) 7: 9 4.1 et seq., Surface Water Quality Standards, are subject to the criteria in paragraph ( d)( 5)( ii) of this section, without exception:

N. J. A. C. 7: 9 4.12( c): Class FW2 N. J. A. C. 7: 9 4.12( d): Class SE1 N. J. A. C. 7: 9 4.12( e): Class SE2 N. J. A. C. 7: 9 4.12( f): Class SE3 N. J. A. C. 7: 9 4.12( g): Class SC ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 5)( i) of this section:

Use classification Applicable criteria FW2 This classification is assigned the criteria in: Column B( 1) all except # 102, 105, 107, 108, 111, 112, 113, 115, 117, and 118. Column B( 2) all except # 105, 107, 108, 111, 112, 113, 115, 117, 118, 119, 120, 121, 122, 123, 124, and 125. Column D( 1) all except # 4, 5a, 5b, 7, 10, and 11. Column D( 2) all. SE1, SE2, SE3, SC These classifications are each assigned the criteria in: Column C( 1) all except # 102, 105, 107, 108, 111, 112, 113, 115, 117, and 118. Column C( 2) all except # 105, 107, 108, 111, 112, 113, 115, 117, 118, 119, 120, 121, 122, 123, 124, and 125. Column D( 2) all.

( 6) Puerto Rico, Region 2 ( i) All waters assigned to the following use classifications in the Puerto Rico Water Quality Standards ( promulgated by Resolution Number R 83 5 2) are subject to the criteria in paragraph ( d)( 6)( ii) of this section, without exception.

Article 2.2.2 Class SB Article 2.2.3 Class SC Article 2.2.4 Class SD ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 6)( i) of this section:

Use classification Applicable criteria Class SD This classification is assigned criteria in: Column B( 1) all, except: 10, 102, 105, 107, 108, 111, 112, 113, 115, 117, and 126. Column B( 2) all, except: 105, 107, 108, 112, 113, 115, and 117. Column D( 1) all, except: 4, 5a, 5b, 6, 7, 10, 11, 14, 105, 112, 113, and 115. Column D( 2) all, except: 4, 5a, 5b, 10, 14, 105, 112, 113, and 115. Class SB, Class SC These classifications are assigned criteria in: Column C( 1) all, except: 4, 5b, 7, 8, 10, 11, 13, 102, 105, 107, 108, 111, 112, 113, 115, 117, and 126. Column C( 2) all, except: 4, 5b, 10, 13, 108, 112, 113, 115, and 117. Column D( 2) all, except: 4, 5a, 5b, 10, 14, 105, 112, 113, and 115.

( 7) Virginia, Region 3 ( i) All waters assigned to the following use classifications in the Virginia Water Quality Standards, VR680 21 are subject to the criteria in paragraph ( d)( 6)( ii) of this section without exception:

VR680 21 08 Classes I VII and PWS ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 7)( i) of this section:

Use classification Applicable criteria Class I This classification is assigned the criteria in: Column C( I) all. Column C( ll) all. Column D( II) all, except # 16. Class II This classification is assigned the criteria in: Column B( I) all. Column B( II) all. Column C( I) all. Column C( II) all. Column D( II) all, except # 16. Class III VII Each of these classifications is assigned the criteria in: Column B( I) all. Column B( II) all. Column D( II) all, except # 16. PWS This classification is assigned the additional criteria in: Column D( I) all, except # 16.

( 8) District of Columbia, Region 3 ( i) All waters assigned to the following use classifications in Chapter 11 Title 21 DCMR, Water Quality Standards of the District of Columbia are subject to the criteria in paragraph ( d)( 8)( ii) of this section without exception:

1101.2 Class C waters ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classification identified in paragraph ( d)( 8)( i) of this section:

Use classification Applicable criteria Class C This classification is assigned the additional criteria in: Column B( II)# 10, 118, 126. Column D( I)# 7, 15, 16, 44, 67, 68, 79, 80, 81, 88, 114, 116, 118. Column D( II) all.

( 9) Florida, Region 4 ( i) All waters assigned to the following use classifications in Chapter 17 301 of the Florida Administrative Code ( i. e., identified in Section 17 302.600) are subject to the criteria in paragraph ( d)( 9)( ii) of this section, without exception:

Class I Class II Class III ( ii) The following criteria from the matrix paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 9)( i) of this section:

Use classification Applicable criteria Class I This classification is assigned the criteria in: Columns B1 and B2 5( b), 6, 7, 8, 9, 10, 11, 107, 111, 115, 118, and 126; and Column D1 all. Class II; Class III ( marine) This classification is assigned the criteria in: Columns C1 and C2 2, 6, 7, 8, 9, 11, 13, 14, 111, 115, 118, and 126; and Column D2 all. Class III ( freshwater) This classification is assigned the criteria in: Columns B1 and B2 5( b), 6, 7, 8, 9, 10, 11, 107, 111, 115, 118, and 126; and Column D2 all.

( 10) Michigan, Region 5 ( i) All waters assigned to the following use classifications in the Michigan Department of Natural Resources Commission General Rules, R 323.1043 Definitions; A to N, ( i. e., identified in Section ( g) " Designated use") are subject to the criteria in paragraph ( d)( 10)( ii) of this section, without exception: ( A) Industrial water supply ( B) Agricultural water supply ( C) Public water supply ( D) Recreation ( E) Fish, other aquatic life, and wildlife ( F) Navigation ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 10)( i) of this section:

Use classification Applicable criteria Public water supply This classification is assigned the criteria in: Column B ( I) all, Column B ( II) all, Column D ( I) all. All other designations These classifications are assigned the criteria in: Column B ( I) all, Column B ( II) all, and Column D ( II) all.

( 11) Arkansas, Region 6 ( i) All waters assigned to the following use classification in Section 4C ( Waterbody uses) identified in Arkansas Department of Pollution Control and Ecology's Regulation No. 2 as amended and entitled, " Regulation Establishing Water Quality Standards for Surface Waters of the State of Arkansas" are subject to the criteria in paragraph ( d)( 11)( ii) of this section, without exception: ( A) Extraordinary Resource Waters ( B) Ecologically Sensitive Waterbody ( C) Natural and Scenic Waterways ( D) Fisheries: ( 1) Trout ( 2) Lakes and Reservoirs ( 3) Streams ( i) Ozark Highlands Ecoregion ( ii) Boston Mountains Ecoregion ( iii) Arkansas River Valley Ecoregion ( iv) Ouachita Mountains Ecoregion ( v) Typical Gulf Coastal Ecoregion ( vi) Spring Water influenced Gulf Coastal Ecoregion ( vii) Least altered Delta Ecoregion ( viii) Channel altered Delta Ecoregion Domestic Water Supply ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classification identified in paragraph ( d)( 11)( i) of this section:

Use classification Applicable criteria Extraordinary resource waters Ecologically sensitive waterbody Natural and scenic waterways Fisheries: ( 1) Trout ( 2) Lakes and reservoirs ( 3) Streams ( a) Ozark highlands ecoregion ( b) Boston mountains ecoregion ( c) Arkansas river valley ecoregion ( d) Ouachita mountains ecoregion ( e) Typical gulf coastal Ecoregion ( f) Spring water influenced gulf coastal ecoregion ( g) Least altered Delta ecoregion ( h) Channel altered Delta ecoregion These uses are each assigned the criteria in Column B1# 2, 4, 5a, 5b, 6, 7, 8, 9, 10, 11, 13, 14. Column B2# 2, 4, 5a, 5b, 6, 7, 8, 9, 10, 13, 14. Column D2 all. Domestic water supply This use is assigned the criteria in: Column D1 all.

( 12) Louisiana, Region 6 ( i) All waters assigned to the following use designations in the Louisiana Administrative Code, Title 33 Environmental Quality, Part IX Water Quality Regulations, Chapter 11 ( i. e., identified in Section 1111 Water Use Designations) are subject to the criteria in paragraph ( d)( 12)( ii) of this section, without exception: ( A) Public Water Supply ( B) Fish and Wildlife Propagation ( C) Oyster Propagation ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 12)( i) of this section:

Use classification Applicable criteria Public water supply This classification is assigned the criteria in: Column D( I)# 16. Fish and wildlife propagation These classifications are assigned the criteria in: Column D( II) # 16. Oyster propagation Column D( II) # 16.

( 13) Kansas, Region 7 ( i) All waters assigned to the following use classification in the Kansas Department of Health and Environment regulations, K. A. R. 28 16 28b through K. A. R. 28 16 28f, are subject to the criteria in paragraph ( d)( 13)( ii) of this section, without exception.

Section 28 16 28d: Section ( 2)( A) Special Aquatic Life Use Waters Section ( 2)( B) Expected Aquatic Life Use Waters Section ( 2)( C) Restricted Aquatic Life Use Waters Section 3 Domestic Water Supply Section ( 6)( c) Consumptive Recreation Use.

( ii) The following criteria from the matrix is paragraph ( b) of this section apply to the use classifications identified in paragraph ( d)( 13)( i) of this section:

Use classification Applicable criteria Sections ( 2)( A), ( 2)( B), ( 2)( C), 6( C) These classifications are each assigned all criteria in: Column B( I), except # 9, 13, 102, 105, 107, 108, 111 113, 115, 117, and 126; Column B( II), except # 9, 13, 105, 107, 108, 111 113, 115, 117, 119 125, and 126; and Column D( II), except # 9, 10, 112, 113, and 115. Section ( 3) This classification is assigned all criteria in: Column D( I), except # 9, 10, 12, 112, 113, and 115.

( 14) Colorado, Region 8 ( i)( A) All waters assigned to the following use classifications in the Colorado Classifications and Numeric Standards for the following Basins: ( 1) Arkansas River Basin 3.2.0 ( 5CCR 1002 8); ( 2) Upper Colorado River Basin and North Platte River Basin ( Planning Region 12) 3.3.0 ( 5CCR 1002 8); ( 3) San Juan and Dolores River Basins 3.4.0 ( 5CCR 1002 8); ( 4) Gunnison and Lower Dolores River Basins 3.5.0 ( 5CCR 1002 8); ( 5) Rio Grande River Basin 3.6.0 ( 5CCR 1002 8); ( 6) Lower Colorado Basin 3.7.0 ( 5CCR 1002 8); ( 7) South Platte River Basin, Laramie River Basin, Republican River Basin, Smoky Hill River Basin 3.8.0 ( 5CCR 1002 8); are subject to the criteria in paragraph ( d)( 14)( ii) of this section, except where only particular segments require criteria as delineated in paragraph ( d)( 14)( ii) of this section.

The following are the use classifications: ( 1) Domestic Water Supply ( 2) Class 1 Cold Water Aquatic Life ( 3) Class 2 Cold Water Aquatic Life ( 4) Class 1 Warm Water Aquatic Life ( 5) Class 2 Warm Water Aquatic Life ( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the use classifications in paragraph ( d)( 14)( i) of this section:

Use classification Applicable criteria Domestic water supply All waters assigned to this use classification are subject to the criteria in: Column D( I) all except # 4, 5a, 5b, 6, 7, 10, 11, 22, 33, 39, 41, 44, 53, 66, 77, 90, 95, 115. Class 1 Cold Water A. L. Class 2 Cold Water A. L. Class 1 Warm Water A. L. Class 2 Warm Water A. L. All waters assigned to these use classifications are subject to the criteria in: Column B( I)# 10. Column B( II)# 10. Column D( II) all and the following specific segments ( which have been assigned one of these aquatic life uses) are further assigned the criteria set forth below.

1. The criteria in: B( I)# 2, 4, 5a, 5b, 6, 7, 8, 9, 11, 13, 14; B( II)# 2, 4, 5a, 5b, 6, 7, 8, 9, 13, 14 are assigned to the following specific segments: ** Basin 3.2.0 Upper Arkansas River Basin: segments 14, 26 Middle Arkansas River Basin: segments 4, 13, 18 Fountain Creek Basin: segments 3a, 8 Lower Arkansas River Basin: segments 2, 6b, 13 Cimarron River Basin: segment 1 ** Basin 3.3.0 Blue River Basin ( 14010002): segments 5, 20 Eagle River Basin ( 14010003): segment 11 North Platte River Basin ( 1018001, 10180002): segment 7 Yampa River Basin ( 14050001, 14050002): segment 12 ** Basin 3.4.0 San Juan River Basin: segments 3, 10, 11 Piedra River Basin: segment 6 Los Pinos River Basin: segment 6 Animas and Florida River Basin: segment 13b La Plata River, Mancos River, McElmo Creek and San Juan River Basin in Montezuma County and Dolores Counties: segments 3, 6, 8 Dolores River Basin: segment 11 ** Basin 3.5.0 Upper Gunnison River Basin: segments 6b, 16, 28, 32 North Fork of the Gunnison River Basin: segment 6, 10 Upcomphgre River Basin: segments 10, 12 Lower Gunnison River Basin: segment 4 San Miguel River Basin: segment 12 Lower Dolores River Basin: segment 4 ** Basin 3.6.0 Rio Grande River Basin: segments 15b, 25 Closed Basin San Luis Valley: segment 3 ** Basin 3.7.0 Lower Yampa River/ Green River Basin: segments 3a, 3b, 6, 14, 17, 20 White River Basin: segments 5, 9, 13a, 22 Lower Colorado River Basin: segments 11b, 11e, 13 ** Basin 3.8.0 Republican River Basin: segments 6, 7 South Platte River Basin ( Region 1): segment 2 Cache La Poudre River Basin: segments 8, 13 Big Thompson River Basin: segments 6, 10 South Platte River Basin ( Region 2): segment 3 St. Vrain Creek Basin: segment 6 Boulder Creek Basin: segments 8, 11 Big Dry Creek Basin: segment 1 Clear Creek Basin: segments 8, 16, 18 Cherry Creek Basin: segment 4 South Platte River Basin ( Regions 2, 3, 4): segments 7a, 11a, 16 South Platte River Basin ( Region 3 and 4): segment 7 2. The criteria in: Column B( I)# 9; Column B( II)# 9 are assigned to the following specific segments:

** Basin 3.3.0 Blue River Basin ( 14010002): segment 12 ** Basin 3.4.0 Animas and Florida River Basin: segment 15 La Plata River, Mancos River, McElmo Creek and San Juan River Basin in Montezuma County and Dolores Counties: segment 9 ** Basin 3.8.0 Big Thompson River Basin: segment 13 Boulder Creek Basin: segments 4c, 6 Clear Creek Basin: segment 12 Bear Creek Basin: segments 4a, 5 South Platte River Basin ( Region 2, 3, and 4): segment 7b 3. The criteria in: Column B( I)# 8; Column B( II)# 8 are assigned to the following specific segments:

** Basin 3.7.0 Lower Colorado River Basin: segment 4 ** Basin 3.8.0 South Platte River Basin ( Region 2, 3, and 4): segment 11b 4. The criteria in: Column B( I)# 14; Column B( II)# 14 are assigned to the following specific segment: ** Basin 3.2.0 Upper Arkansas River Basin: segment 8b 5. The criterion in: Column B( I)# 11 is assigned to the following specific segment: ** Basin 3.7.0 Lower Colorado River Basin: segment 4.

( 15) Arizona, Region 9 ( i) All waters assigned the use classifications in chapter 21 of the Arizona Administrative Code ( AAC) which are referred to in paragraph ( d)( 15)( ii) of this section, are subject to the criteria in paragraph ( d)( 15)( ii) of this section, without exception. These criteria amend the existing State standards contained in chapter 21 of the AAC sections R9 21 101 through 304, Water Quality Standards for Waters of the State, for the toxic pollutants identified in paragraph ( d)( 15)( ii) of this section. For purposes of this action, the specific standards to be applied are based on the following selected use designations as defined in chapter 21, AAC Secs. R9 21 101 through R9 21 304: ( A) DWS Domestic Water Source ( B) A& W Aquatic & Wildlife ( including any aquatic life designation)

( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the water and use classifications defined in paragraph ( d)( 15)( i) of this section and identified below:

Water and use classification Applicable criteria Waters of the State with A& W but These waters are assigned the without DWS criteria in: Column B1 all pollutants. Column B2 all pollutants. Column D2 all pollutants. Waters of the State with A& W and DWS These waters are assigned the criteria in: Column B1 all pollutants. Column B2 all pollutants. Column D1 all pollutants. Waters of the State with DWS but These waters are assigned the without A& W criteria in: Column D1 all pollutants.

( 16) California, Region 9 ( i) All waters assigned any aquatic life or human health use classifications in the Water Quality Control Plans for the various Basins of the State (" Basin Plans"), as amended, adopted by the California State Water Resources Control Board (" SWRCB"), except for ocean waters covered by the Water Quality Control Plan for Ocean Waters of California (" Ocean Plan") adopted by the SWRCB with resolution Number 90 27 on March 22, 1990, are subject to the criteria in paragraph ( d)( 16)( ii) of this section, without exception. These criteria amend the portions of the existing State standards contained in the Basin Plans. More particularly these criteria amend water quality criteria contained in the Basin Plan Chapters specifying water quality objectives ( the State equivalent of federal water quality criteria) for the toxic pollutants identified in paragraph ( d)( 16)( ii) of this section. Although the State has adopted several use designations for each of these waters, for purposes of this action, the specific standards to be applied in paragraph ( d)( 16)( ii) of this section are based on the presence in all waters of some aquatic life designation and the presence or absence of the MUN use designation ( Municipal and domestic supply). ( See Basin Plans for more detailed use definitions).

( ii) The following criteria from the matrix in paragraph ( b) of this section apply to the water & use classifications defined in paragraph ( d)( 16)( i) of this section and identified below:

Water and use classification Applicable criteria Waters of the state defined as bays These waters are assigned the or estuaries except the Sacramento criteria in: San Joaquin Delta and San Francisco Bay Column B1 all pollutants. Column B2 all pollutants. Column C1 all pollutants. Column C2 all pollutants. Column D2 all pollutants. Waters of the Sacramento San Joaquin These waters are assigned the Delta and waters of the state criteria in: defined as inland ( i. e., all surface waters of the state not bays or estuaries or ocean) that include a MUN use designation except the San Joaquin River from the mouth of the Merced River to Vernalis and the Sacramento River and its tributaries upstream from Hamilton City Column B1 all pollutants. Column B2 all pollutants. Column D1 all pollutants. Waters of the state defined as inland These waters are assigned the without an MUN use designation criteria in: except waters flowing to Grasslands Water District, San Luis National Wildlife Refuge and Los Banos State Wildlife Area Column B1 all pollutants. Column B2 all pollutants. Column D2 all pollutants. Waters of the San Joaquin River from These waters are assigned the the mouth of the Merced River to criteria in: Vernalis Column B1 all pollutants except # 10. Column B2 all pollutants. Column D1 all pollutants except # 10. Waters of the Sacramento River and These wates are assigned the criteria its tributaries upstream from in: Hamilton City Column B1 all pollutants except # 4, 6, 13. Column B2 all pollutants except # 4, 6, 13. Column D1 all pollutants except # 4. Waters flowing to Grasslands Water These waters are assigned the District, San Luis National Wildlife criteria in: Refuge, and Los Banos State Wildlife Area Column B1 all pollutants. Column B2 all pollutants. Column D2 all pollutants except # 10. Waters of San Francisco Bay These waters are assigned the criteria in: Column B1 all pollutants. Column B2 all pollutants. Column C1 all pollutants except # 10. Column C2 all pollutants except # 10. Column D2 all pollutants.