Chapter3-WaterQualityCriteria

CHAPTER 3 WATER QUALITY CRITERIA

The term “water quality criteria” hastwo different definitions under the Clean Water Act (CWA). Under section 304(a), EPA publishes water quality criteria that consist of scientific information regarding concentrations of specific chemicals or levels of parameters in water that protect aquatic life and human health (see section 3.1 of this Handbook). The States may use these contents as the basis for developing enforceable water quality standards. Water quality criteria are also elements of State water quality standards adopted under section 303(c) of the CWA (see sections 3.2 through 3.6 of this Handbook). States are required to adopt water quality criteria that will protect the designated use(s) of awater body. These criteria must be based on sound scientific rationale and must contain sufficient parameters or constituents to protect the designated use.

3.1 EPA Section 304(a) Guidance

EPA and a predecessor agency have produced a series of scientific water quality criteria guidance documents. Early Federal efforts were the “Green Book” (FWPCA, 1968) and the “Red Book” (USEPA, 1976). EPA also sponsored a contract effort that resulted in the “Blue Book” (NAS/NAE, 1973). These early efforts were premised on the use of literature reviews and the collective scientific judgment of Agency and advisory panels. However, when faced with the need to develop criteria for human health aswell
as aquatic life, the Agency determined that new procedures were necessary. Continued reliance solely on existing scientific literature was deemed inadequate because essential information was not available for many pollutants. EPA scientists developed formal methodologies for establishing scientifically defensible criteria. These were subjected to review by the Agency’s Science Advisory Board of outside experts and the public. This effort culminated on November 28, 1980, when the Agency published criteria development guidelines for aquatic life and for human health, along with criteria for 64 toxic pollutants (USEPA, 1980a,b). Since that initial publication, the aquatic life methodology was amended (Appendix H), and addition al criteria were proposed for public comment and finalized as Agency criteria guidance. EPA summarized the available criteria information in the “Gold Book” (USEPA, 1986a), which is updated from time to time. However. the individual criteria documents (see Appendix I). as updated, are the official guidance documents.

EPA’s criteria documents provide a comprehensive toxicological evaluation of each chemical. For toxic pollutants, the documents tabulate the relevant acute and chronic toxicity information for aquatic life and derive the criteria maximum concentrations (acute criteria) and criteria continuous concentrations (chronic criteria) that the Agency recommends to protect aquatic life resources. The methodologies for these processes are described in Appendices H and Jand outlined in sections 3.1.2 and 3.1.3 of this Handbook.

3.1.1 State Use of EPA Criteria Documents

EPA’s water quality criteria documents are available to assist States in:

• adopting water quality standards that include appropriate numeric water quality criteria;

• interpreting existing water quality standards that include narrative “no toxics in toxic amounts” criteria;

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• making listing decisions under section 304(1) of the CWA;

• writing water quality-based NPDES permits and individual control strategies; and

• providing certification under section 401 of the CWA for any Federal permit or license (e.g., EPA-issued NPDES permits, CWA section 404 permits, or Federal Energy Regulatory Commission licenses).

In these situations, States have primary authority to determine the appropriate level to protect human health or welfare (in accordance with section 303(c)(2) of the CWA) for each water body. However, under the Clean Water Act, EPA must also review and approve State water quality standards; section 304(1) listing decisions and draft and final State-issued individual control strategies; and in States where EPA writes NPDES permits, EPA must develop appropriate water quality-based permit limitations. The States and EPA therefore have a strong interest in assuring that the decisions are legally defensible,

are based on the best information available, and
are subject to full and meaningful public comment and participation. It is very important that each decision be supported by an adequate record. Such a record is critical to meaningful comment, EPA’s review of the State’s decision, and any subsequent administrative or judicial review.

Any human health criterion for atoxicant is based

on at least three interrelated considerations:

• cancer potency or systemic toxicity.

• exposure. and

• risk characterization.

States may make their own judgments on each of these factors within reasonable scientific bounds, but documentation to support their judgments, when different from EPA’s recommendation, must beclear and in the public record. If aState relies

on EPA’s section 304(a) criteria document (or other EPA documents), the State may reference and rely on the data in these documents and need not create duplicative or new material for inclusion in their records. However, where sitespecific issues arise or the State decides to adopt
an approach to any one of these three factors that differs from the approach in EPA’s criteria document, the State must explain its reasons in a
manner sufficient for areviewer to determine that the approach chosen is based on sound scientific rationale (40 CFR 131.11 (b)).

3.1.2 Criteria for Aquatic Life Protection

The development of national numerical water quality criteria for the protection of aquatic organisms is a complex process that uses information from many areas of aquatic toxicology. (See Appendix H for a detailed discussion of this process.) After a decision is made that a national criterion is needed for a particular material, all available information concerning toxicity to, and bioaccumuiation by. aquatic organisms is collected and reviewed for acceptability. If enough acceptable data for 48- to 96-hour toxicity tests on aquatic plants and animals are available, they are used to derive the acute criterion. If sufficient data on the ratio of acute to chronic toxicity concentrations are available, they are used to derive the chronic or long-term exposure criteria. If justified, one or both of the criteria may be related to other water quality characteristics, such as pH, temperature,
or hardness. Separate criteria are developed for fresh and salt waters.

The Water Quality Standards Regulation allows States to develop numerical criteria or modify

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EPA’s recommended criteria to account for site-specific or other scientifically defensible factors. Guidance on modifying national criteria is found in sections 3.6 and 3.7. When a criterion must be developed for 

### achemical for which a national criterion has not been established, the regulatory authority should refer tothe EPA guidelines (Appendix H).


### Magnitude for Aquatic Life Criteria

Water quality criteria for aquatic life contain two expressions of allowable magnitude: acriterion maximum concentration (CMC) toprotect against acute (short-term) effects; and a criterion continuous concentration (CCC) toprotect against chronic (long-term) effects. EPA derives acute criteria from 48- to 96-hour tests of lethality or immobilization. EPA derives chronic criteria from longer term (often greater than 28-day) tests that measure survival, growth, or reproduction. Where appropriate, thecalculated criteria maybe lowered to be protective ofcomercially or recreationally important species.



### Duration for Aquatic Life Criteria

The quality ofanambient water typically varies in response to variations of effluent quality, stream flow, and other factors. Organisms in the receiving water are not experiencing constant, steady exposure but rather are experiencing fluctuating exposures, including periods of high concentrations, which may have adverse effects. Thus, EPA’s criteria indicate atime period over which exposure isto beaveraged, aswell asan upper limit ontheaverage concentration, thereby limiting the duration of exposure to elevated concentrations. For acute criteria, EPA recommends anaveraging period of 1hour. That is, to protect against acute effects, the l-hour average exposure should not exceed the CMC. For chronic criteria, EPA recommends an averaging period of 4 days. That is, the 4-day average exposure should not exceed theCCC. 

### Frequency for Aquatic Life Criteria

To predict or ascertain theattainment of criteria, it isnecessary tospecify the allowable frequency for exceeding the criteria. This is because it is statistically impossible to project that criteria will
never be exceeded. As ecological communities
are naturally subjected toaseries of stresses, the allowable frequency of pollutant stressmay beset atavalue that does not significantly increase the frequency or severity of all stresses combined.

EPA recommends an average frequency for excursions of both acute and chronic criteria not to exceed once in 3 years. In all cases, the recommended frequency applies toactual ambient concentrations, and excludes the influence of measurement imprecision. EPA established its recommended frequency aspart of its guidelines for deriving criteria (Appendix H). EPA selected the 3-year average frequency of criteria exceedence with the intent of providing for ecological recovery from a variety of severe stresses. This return interval is roughly equivalent to a 7410 design flow condition. Because of the nature of the ecological recovery studies available, the severity of criteria excursions could not be rigorously related to the resulting ecological impacts. Nevertheless, EPA derives itscriteria intending thatasingle marginal criteria excursion (i.e., aslight excursion over a l-hour period for acute orover a4-day period for chronic) would require little or no time for recovery. If the frequency of marginal criteria excursions is not high, it can be shown that the frequency ofseverestresses, requiring measurable recovery periods, would be extremely small. EPA thus expects the 3-year return interval to provide avery high degree of protection.



### 3.1.3 Criteria for Human Health Protection

This section reviews EPA’s procedures used to develop assessments of human health effects in developing water quality criteria and reference ambient concentrations. A more complete human health effects discussion is included in the 

### Guidelines undMerhtnioiog~ UsedinIhe

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### Preparation 

## ofHealrh EflecfsAssessmensChapters of the Consenr Decree Wur4r Docwnents (Appendix J). The procedures contained in this document are used in the development and updating of EPA water quality criteria andmaybe used in updating State criteria and in developing State criteria for those pollutants lacking EPA human health criteria. The procedures may also be applied as site-specific interpretations of narrative standards andasabasisfor permit limits under 40 CFR 122.44 (d)(l)(vi).


### Magnitude and Duration

Water quality criteria for human health contain only asingle expression of allowable magnitude;
a criterion concentration generally to protect against long-term (chronic) human health effects. Currently, national policy and prevailing opinion in the expert community establish that the duration for human health criteria for carcinogens should be derived assuming lifetime exposure, taken to bea70-year time period. The duration of exposure assumed in deriving criteria for noncarcinogens is more complicated owing to a wide variety of endpoints: some developmental (and thus age-specific and perhaps genderspecific), some lifetime. and some, such as organoleptic effects. not duration-related at all. Thus, appropriate durations depend on the individual noncarcinogenic pollutants and the endpoints or adverse effects being considered.



### Human Exposure Considerations

A complete human exposure evaluation for toxic polIutants of concern for bioaccumulation would encompass not only estimates ofexposures dueto fish consumption but also exposure from background concentrations and other exposure routes, The more important of these include recreational and occupational contact, dietary intake from other than fish, intake from air inhalation, anddrinking water consumption. For section 304(a) criteria de\,elopment, EPAtypically considers only exposures toapollutant that occur through the ingestion of water and contaminated fish and shellfish. This is the exposure default assumption, although thehuman health guidelines provide for considering other sources where data
are available (see 45 F.R. 79354). Thus the criteria are based on an assessment of risks related to the surface water exposure route only (57 F.R. 60862-j).

The consumption ofcontaminated fish tissue isof serious concern because the presence of even extremely low ambient concentrations of bioaccumulative pollutants (sublethal to aquatic life) in surface waters can result in residue concentrations infish tissuethatcanposeahuman health risk. Other exposure route information should beconsidered and incorporated in human exposure evaluations tothe extent available.

Levels of actual human exposures from consuming contaminated fishvary depending upon a number of case-specific consumption factors. These factors include type of fish species consumed, type of fish tissue consumed, tissue lipid content, consumption rate and pattern. and foodpreparation practices. Inaddition, depending
on the spatial variability in the fishery area, the behavior of the fish species, and the point of application of thecriterion. theaverage exposure of fish may be only a small fraction of the expected exposure at the point of application of the criterion. If an effluent attracts fish. the average exposure might be greater than the expected exposure.

With shellfish, such as oysters, snails, and mussels. whole-body tissue consumption commonly occurs, whereas with fish, muscle tissue and roe are most commonly eaten. This difference in the types of tissues consumed has implications for the amount of available bioaccumulative contaminants likely to be ingested. Whole-body shellfish consumption presumably means ingestion of the entire burden ofbioaccumulative contaminants. However, with most fish. selective cleaning and removal of internal organs, and sometimes body fat aswell, from edible tissues, may result in removal of much of the lipid material in which bioaccurnulative contaminants tendtoconcentrate.

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### Fish Consumption Values

EPA’s human health criteria have assumed a human body weight of 70kgandtheconsumption 

### of 6.5 gof fish and shellfish per day. Basedon data collected in 1973-74, the national per capita consumption of freshwater andestuarine fish was estimated to average 6.5 g/day. Per capita consumption of all seafood (including marine species) was estimated to average 14.3 g/day. The 95th percentile forconsumption ofallseafood by individuals over a period of 1 month was estimated tobe42g/day. The mean lipid content of fish and shellfish tissue consumed in this study
wasestimated tobe3.0 percent (USEPA, 198Oc).

Currently, four levels of fish and shellfish consumption are provided in EPA guidance (USEPA, 1991a):

l 6.5 g/day torepresent anestimate ofaverage consumption of fish and shellfish from estuarine and freshwaters by theentire U.S. population. This consumption level isbased
on the average of both consumers and
nonconsumers of.

l 20 g/day to represent an estimate of the average consumption of fish and shellfish from marine, estuarine, and freshwaters by the IJ.S. population. This average consumption level also includes both
consumers and nonconsumers of,

l 165 g/day to represent consumption of fish and shellfish from marine, estuarine, and freshwaters by the 99.9th percentile of the U.S. population consuming the most fish or seafood.

l 180 g/day to represent a “reasonable worst case” based on the assumption that some individuals would consume fishand shellfish atarate equal tothecombined consumption of red meat, poultry, fish, and shellfish in the llnited States. EPA iscurrently updating the national estuarine and freshwater fish and shellfish consumption default values and will provide a range of recommended national consumption values. This range will include:

l meanvalues appropriate tothe population at large; and

l values appropriate for those individuals who
consume arelatively large proportion offish and shellfish in their diets (maximally exposed individuals).

Many States use EPA’s 6.5 g/day consumption value. However, some States use the abovementioned 20 g/day value and, for saltwaters, 37g/day. In general, EPA recommends that the consumption values usedinderiving criteria from the formulas in this chapter reflect the most current, relevant, and/or site-specific information available.



### Bioaccumulat ion Consider-at ions

The ratio ofthecontaminant concentrations infish tissue versus that in water is termed either the bioconcentration factor (BCF) or the bioaccumulation factor (BAF). Rioconcentration isdefined asinvolving contaminant uptake from water only (not from food). The bioaccumulation factor (RAF) is defined similarly to the BCF except that it includes contaminant uptake from both water and food. Under laboratory conditions, measurements of tissue/water partitioning are generally considered to involve uptake from water only. On theother hand, both processes are likely toapply in the field since the entire food chain isexposed.

The BAF/BCF ratio ranges from 1to 100. with thehighest ratios applying toorganisms in higher trophic levels, and tochemicals with logarithm of the octanol-water partitioning coefficient (log P) clo.scto6.5.

Bioaccumulation considerations areintegrated into the criteria equations by using food chain

(8/15!94) 3-smultipliers (FMs) in conjunction with the BCF.

The bioaccurnulation and bioconcentration factors for achemical are related asfollows:



### BAF = Fhl xBCF

By incorporating the FM and BCF terms into the criteria equations, bioaccumulation can be addressed.

In Table 3-1, FM values derived from the work of Thomann (1987, 1989) are listed according to log Pvalue and trophic level of the organism. For chemicals with log P values greater than about 7. there isadditional uncertainty regarding the degree of bioaccumulation, but generally, trophic level effects appear to decrease due to slow transport kinetics of thesechemicals in fish, the growth rate of the fish, and the chemical’s relatively low bioavailability. Trophic level 4 organisms aretypically the mostdesirable species for sport fishing and, thcrcfore, FMs for trophic level 4should generally be used in theequations for calculating criteria. In those \crv rare situations where only lower trophic level organisms are found, e.g., possibly oyster beds,
an FM for a lower trophic level might be considered.

Measured BAFs (especially for those chemicals with log P values above 6.5) reported in the literature should beusedwhen available. To use experimentally measured BAFs in calculating the criterion, the(FM xBCF) term isreplaced bythe BAF in the equations in the following section, Relatively few BAFs have been measured accurately and reported, and their application to sitesother than thespecific ecosystem where they
were developed is problematic and subject to uncertainty. The option is also available to develop BAFs experimentally, but this will be extremely resource intensive if done on a sitespecific basis with all the necessary experimental andquality controls. Trophic Levels

____________________------------------------------------- _-_---_ Loi%p 2 3 4

________________________________________---------------------- 3.5 1.0 I.o 1.0 3.6 1.0 I.o 1.o 3.7 1.0 1.o 1.0 3.8 1.0 1.0 1.0 3.9 1.0 1.o 1.0 4.0 1.1 1.o 1.0 4.1 1.1 1.1 1.1 4.2 1.1 1.1 1.1 4.3 1.1 1.1 1.1 4.4 1’

.& 1.1 1.1 4.5 13

.& 1.2 1.2 4.6 1.2 1.3 1.3 4.7 1.3 1.4 1.4 4.8 1.4 1.5 1.6 4.9 1.5 1.8 2.0 5.0 1.6 2.1 2.6 5.1 1.7 2.5 3.2 5.2 1.9 3.0 4.3 5.3 2.2 3.7 5.8 5.4 2.4 4.6 8.0 5.5 2.8 5.9 11 5.6 3.3 7.5 16 5.7 3.9 9.8 u 5.8 4.6 13 33 5.9 5.6 17 47 6.0 6.8 21 67 6.1 8.2 25 75 6.2 10 29 84 6.3 13 34 92 6.4 15 39 98 6.5 19 45 100 26.5 19.2’ 4s 100’

----------------------_--_--_---------------------------------

*These recommended FMs are conservative estimates; FMs for log Pvalues greater than 6.5 may range from thevdiues given toa low as0.1 for contaminants with very low b~oavailabihty.



### Table 3-1. Estimated Food Chain

hlultipliers (FMs)

Updating Human Health Criteria Using IRIS

EPA recommends that Statesusethemost current risk information intheprocess of updating human

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health criteria. The Integrated Risk Information System (IRIS) (Barns and Dourson, 1988; Appendix N) is an electronic data base of the USEPA that provides chemical-specific risk information onthe relationship between chemical exposure andestimated human health effects. Risk assessment information contained in IRIS, except
as specifically noted, has been reviewed and agreed upon by an interdisciplinary group of scientists representing various Program Offices within the Agency and represent anAgency-wide
consensus. Risk assessment information and values are updated on a monthly basis and are approved for Agency-wide use. IRIS is intended to make risk assessment information readily available to those individuals who must perform risk assessments and also to increase consistency among risk assessment/risk management decisions.

IRIS contains two types of quantitative risks values: the oral Reference Dose (RfD) and the carcinogenic potency estimate or slope factor. The RfD (formerly known astheacceptable daily intake or ADI) is the human health hazard assessment for noncarcinogenic (target organ) effects. The carcinogenic potency estimate (formerly known as q,*) represents the upper bound cancer-causing potential resulting from lifetime exposure toasubstance. The RfD orthe oral carcinogenic potency estimate is usedin the derivation of EPA human health criteria.

EPA periodically updates risk assessment information, including RfDs, cancer potency estimates, and related information oncontaminant effects, and reports the current information on IRIS. Since IRIS contains the Agency’s most recent quantitative risk assessmentvalues, current IRIS values should beusedby Statesin updating
or developing 

### new human health criteria. This
means that the 1980 human health criteria should be updated with the latest IRIS values. The procedure for deriving an updated human health water quality criterion would require inserting the current Rfd or carcinogenic potency estimate on IRIS into the equations in Exhibit 3.1 or 3.2, as appropriate. Evdua!eoUw aourceeddrtC e.g.,FDAaction kvela,MClA,fbk auoument fi8h amauumgti adviaofy levela



### FigUIT!3-l. Procedure for determining an

updated criterion using IRIS data.
Figure 3-l shows the procedure for determining
an updated criterion using IRIS data. If a chemical has both carcinogenic and noncarcinogenic effects, i.e., both acancer potency estimate and a RfD, both criteria should be calculated. The most stringent criterion applies.


### Caiculoting Criteria for Non-carcinogens

The RfD isan estimate of the daily exposure to the human population that is likely to bewithout appreciable risk of causing deleterious effects during alifetime. The RfD isexpressed in units of mg toxicant per kg human body weight per hY*

RfDs arederived from the “no-observed-adverseeffect level” (NOAEL) or the “lowest-observedadverse-effect level” (LOAEL) identified from chronic orsubchronic human epidemiology studies
or animal exposure studies. (Note: “LOAEL”

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and “NOAEL” refer to animal and human toxicology and are therefore distinct from the atpli3tiC toxicity terms “no-observed-effect concentration” (NOEC) and “lowest-observedeffect concentration” (LOEC) .) Uncertainty factors arethen applied totheNOAEL orLOAEL toaccount for uncertainties in the dataassociated with variability among individuals, extrapolation from nonhuman test species to humans, data on other than long-term exposures, andthe useof a LOAEL (USEPA, 1988a). An additional uncertainty factor may beapplied to account for significant weakness or gaps in thedatabase.

The RfD is a threshold below which systemic toxic effects are unlikely to occur. While exposures above the RfD increase theprobability ofadverse effmts, they donot produce acertainty of adverse effects. Similarly, while exposure at
or below the RfD reduces the probability, itdoes notguarantee theabsence ofeffects inall persons. The RfDs contained in IRIS are values that represent EPA’s consensus (and have uncertainty spanning perhaps an order of magnitude). This
meansanRfD of 1.Omg/kg/day could range from 0.3 to 3.0 mg/kg/day.

For noncafcinogenic effects, anupdated criterion
canbederived using theequation in Exhibit 3-l.

If the receiving water body is not used as a drinking water source, the factor WI can be deleted. Where dietary and/or inhalation exposure values are unknown, these factors may bedeleted from the above calculation.


### Galcuhting Criteria for Carcinogens
Any human health criterion for a carcinogen is basedonatleastthree interrelated considerations:
cancer potency, exposure, and risk characterization. When developing Statecriteria, Statesmay make their own judgments on eachof thesefactors within reasonable scientific bounds, but documentation to support their judgments must beclear and in the public record. Maximum protection of human health from the potential effects of exposure to carcinogens through the consumption of contaminated fish and/or other aquatic life would require acriterion of zero. The zero level is based upon the assumption of non-threshold effects (i.e., no safe level exists below which any increase in exposure doesnot result in anincreased risk of cancer) for carcinogens. However, because a publicly acceptable policy for safety does not require the absence of all risk, a numerical estimate of pollutant concentration (in pgll) which corresponds to a given level of risk for a population of aspecified size isselected instead. A cancer risk level is defined asthe number of
new cancers that may result in a population of specified size due to an increase in exposure (e.g., lo4 risk level = 1additional cancer in a population of 1million). Cancer risk iscalculated by multiplying theexperimentally derived cancer potency estimate by the concentration of the chemical in the fish and theaverage daily i.uman consumption ofcontaminated fish. The risk for a specified population (e.g., 1million people or 10. “) isthen calculated by dividing the risk level by the specific cancer risk. EPA’s ambient water quality criteria documents provide risk levels ranging from IO5to 10’ asexamples.

The cancer potency estimate, or slope factor (formerly known as the q,*), is derived using animal studies. High-dose exposures are extrapolated to low-dose concentrations and adjusted toalifetime exposure period through the
useof alinearized multistage model. The model calculates theupper 95percent confidence limit of the slope of a straight line which the model postulates tooccur atlow doses. When basedon human (epidemiological) data, the slope factor is basedontheobserved increase in cancer risk and is not extrapolated. For deriving criteria for carcinogens, theoral cancer potency estimates or slope factors from IRIS are used.

It isimportant tonote that cancer potency factors mayoverestimate orunderestimate theactual risk. Such potency estimates are subject to great uncertainty because of two primary factors:

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## C(mg/l) = J&fDxWTl lDT+INlxWT m WI+fFCxLxF’MxBCF”J where:

C

IN

WI

FC

L

FM

BCF 

### updatedwater quality criterion (mg/l)

oral reference dose(mg toxicant& human My weight/day)
weight 

### ofanaveragehumanadult (70kg)
dietary 

### exposure (other than fish) (mg toxicantikg body human weight/day)

inhalation exposure (mg toxicant/kg body human weight/day)

average human adult water intake (2 l/day)
daily fish consumption (kg 

### fish/day)

ratio of lipid fraction of fish tissue consumed to 3%

food chain multiplier 

### (from Table 3-1)

bioconcentration factor (mg toxicant@ fish divided by mg toxicant/L water) for 

### fishwith 3% lipid content



### Exhibit 3-1. Equation for Deriving Human Health Criteria BasedonNoncarcinogenic Effects

l adequacy of the cancer data base (i.e., human vs. animal data); and

l limited information regarding themechanism of cancer causation.

Risk levels of IO”, 10d, and 10.’ are often used by States as minimal risk levels in interpreting their standards. EPA considers risks to be additive, i.e., the risk from individual chemicals is not necessarily the overall risk from exposure 

### towater. For example, anindividual risk level of lo4 may yield a higher overall risk level if multiple carcinogenic chemicals are present.

For carcinogenic effects, the criterion can be determined by using theequation in Exhibit 3-2. If the receiving water body isnot designated asa drinking water source, the factor WI can be deleted.


### Den’ving Quadative Risk Assessments in theAbsence 

### ofIRIS Values

The Rfl)s or cancer 

### potency estimates comprise the existing dose-response factors for developing criteria. When IRIS data are unavailable, quantitative risk level information may be developed according toaState’s own procedures. Some States have established their own procedures whereby dose-response factors canbe developed based upon extrapolation of acute and/or chronic animal data to concentrations of exposure protective of fish consumption by

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where:

C

RL

91*

wl

FC

L

FM

BCF 

### q*[WI+FCxLx(F’MxBCE)]

updated water quality criterion (mg/l)

risk level (10’) where xisusually in the range of 4to6
weight of anaverage human adult (70 kg)
carcinogenic potency factor (kg day/mg)

average human adult water intake (2 l/day)
daily fish consumption (kg fish/day)

ratio of lipid fraction of 

### fishtissueconsumed to 3% assumed by EPA

food chain multiplier (from Table 3-l)

bioconcentration factor (mg toxicant/kg fish divided by mg toxicant/L water) for fish with 3% lipid content



### Exhibit 3-2. Equation for Deriving Human Health Criteria BasedonCarcinogenic Effects

humans. 

# I 3.2 Relationship of Section 304(a) Criteria toState Designated Uses

The section 304(a)( 1)criteria published by EPA from time to time can be used to support the designated uses found in 

### State standards. The following sections briefly discuss the relationship between certain criteria and individual use classifications. Additional information on this subject also can be found in the “Green Book” (FWPCA, 1968); the “Blue Book” (NAUNAE, 1973); the “Red Rook” USEPA, 1976); the EPA 

### WaterQuality Criteria Documem (seeAppendix I); the”Gold Rook” (USEPA, 198&t); and future EPA section 304(a)(l) water quality criteria publications. Where awater body isdesignated for more than
one use, criteria necessary to protect the most sensitive usemustbeapplied. The following four sections discuss themajor typesof usecategories.



### 3.2.1 Recreation

Recreational usesof water include activities such
as swimming, wading, boating, and fishing. Often insufficient data exist on the human health effects of physical and chemical pollutants, including mosttoxics, to makeadetermination of criteria for recreational uses. However, as a general guideline, recreational waters that contain chemicals in concentrations toxic or othenvise harmful to man if ingested, or irritating to the skin or mucous membranes of the human body

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upon brief immersion, should beavoided. The section 304(a)(l) human health effects criteria based on direct human drinking water intake and fish consumption might provide useful guidance in these circumstances. Also, section 304(a)(l) criteria based on human health effects may be usedto support this designated usewhere fishing isincluded in theStatedefinition of “recreation.” In this latter situation, only the portion of the criterion based on fish consumption should be Used. Section 304(a)(l) criteria to protect recreational uses are also available for certain physical, microbiological, and narrative “free from” aesthetic criteria.

Research regarding bacteriological indicators has resulted in EPA recommending that States use 

### Ercherichia coli or enterococci as indicators of recreational water quality (USEPA, 1986b) rather than fecal coliform because of the better correlation with gastroenteritis in swimmers.

The “Green Book” and “Blue Book” provide additional information on protecting recreational
usessuch aspH criteria to prevent eye irritation and microbiological criteria based on aesthetic considerations.



### 3.2.2 Aquatic Life

The section 304(a)(l) criteria for aquatic life should beuseddirectly tosupport this designated If subcategories of this use are adopted ye?;., to differentiate between coldwater and warmwater fisheries), then appropriate criteria should besetto reflect thevarying needsof such subcategories.



### 3.2.3 Agricultural and Industrial Uses

The “Green Book” (FWPCA, 1968) and “Blue Book” (NASINAE, 1973) provide some information on protecting agricultural and industrial uses. Section 304(a)(l) criteria for protecting these uses have not been specifically developed for numerous parameters pertaining to these uses, including most toxics. Where criteria have not been specifically developed for these uses, the criteria developed for human health and aquatic life are usually sufficiently stringent toprotect these uses. States mayalsoestablish criteria specifically designed to protect these uses.



### 3.2.4 Public Water Supply

The drinking water exposure component of the section 304(a){ 1)criteria based on human health effects canapply directly tothis useclassification. The criteria also may beappropriately modified depending upon whether thespecific water supply system falls within the auspices of the Safe Drinking Water Act’s (SDWA) regulatory control andthetypz and level of treatment imposed upon the supply before delivery tothe consumer. The SDWA controls the presence of contaminants in finished (“at-the-tap”) drinking water.

A brief description of relevant sections of the SDWA is necessary to explain how the Act will work inconjunction with section 304(a)( 1)criteria in protecting human health from the effects of toxics due toconsumption of water. Pursuant to section 1412oftheSDWA, EPA haspromulgated “National Primary Drinking Water Standards” for certain radionuclide, microbiological, organic, and inorganic substances. These standards establish maximum contaminant levels (MCLs), which specify the maximum permissible level of a contaminant in water that may be delivered to a user of a public water system now defined as serving a minimum of 25 people. MCLs are established based on consideration of arange of factors including not only thehealth effects ofthe contaminants but also treatment capability, monitoring availability, and costs. Under section 1401(l)(D)(i) oftheSDWA, EPA isalso allowed toestablish theminimum quality criteria for water that may be taken into a public water supply system.

Section 304(a)(l) criteria provide estimates of pollutant concentrations protective of human health, but do not consider treatment technology, costs, and other feasibility factors. The sectionWar Quality Straduds HandhA -Scumd Edition

304(a)(l) criteria also include fish bioaccumulation and consumption factors in addition to direct human drinking water intake. These numbers were not developed to serve as “at-the-tap” drinking water standards, and they havenoregulatory significance under theSDWA. Drinking water standards areestablished basedon considerations, including technological and economic feasibility, not relevant to section 304(a)( 1)criteria. Section 304(a)(l) criteria are more analogous to the maximum contaminant level goals (MCLGs) (previously known as RMCLs) under section I412(b)(l)(B) of the SDWA in which, based upon a report from the National Academy of Sciences, theAdministrator should set target levels for contaminants in drinking water atwhich “no known oranticipated adverse effects occur andwhich allow anadequate margin ofsafety.” MCLGs donottaketreatment, cost, and other feasibility factors into consideration. Section 304(a)(l) criteria are, in concept, related tothehealth-based goalsspecified in the MCLGs.

MCLs of the SDWA, where they exist, control toxic chemicals in finished drinking water. However, because of variations in treatment, ambient water criteria may beused by the States
as a supplement to SDWA regulations. When setting water quality criteria for public water supplies, States have the option of applying MCLs, section 304(a)(l) human health effects criteria, modified section 304(a)(l) criteria, or controls more stringent than thesethree toprotect against the effects of contaminants by ingestion from drinking water.

For treated drinking water supplies serving 25 people or greater, States must control contaminants down to levels at least asstringent
asMCLs (where they exist for the pollutants of concern) in the finished drinking water. However, States also have the options tocontrol toxics in the ambient water by choosing section 304(a)( 1) criteria, adjusted section 304(a)( 1) criteria resulting from the reduction of thedirect drinking water exposure component inthecriteria calculation totheextent thatthetreatment process reducesthelevel ofpollutants, oramore stringent contaminant level than the former three options.

cl 

## 3.3 State Criteria Requirements

Section I31.1l(a)( 1)of the Regulation requires Statestoadopt water quality criteria toprotect the designated use(s). The State criteria must be based on sound scientific rationale and must contain sufficient parameters or constituents to protect the designated use(s). For waters with multiple use designations, the criteria must support the most sensitive use.

In section 131.11, Statesareencouraged toadopt both numeric and narrative criteria. Aquatic life criteria should protect against both short-term (acute) and long-term (chronic) effects. Numeric criteria areparticularly important where thecause of toxicity is known or for protection against pollutants with potential human health impacts or bioaccumulation potential. Numeric water quality criteria may also be the 

### best way to address nonpoint source pollution problems. Narrative criteria can be the basis for limiting toxicity in wastedischarges where aspecific pollutant canbe identified ascausing orcontributing tothetoxicity but where there are no numeric criteria in the State standards. Narrative criteria also can be used where toxicity cannot be traced to a particular pollutant.

Section 131.1l(a)(2) requires States to develop implementation procedures which explain how the Statewill ensure that narrative toxics criteria are met.

To more fully protect aquatic habitats, it isEPA’s policy thatStatesfully integrate chemical-specific, whole-effluent, and biological assessment approaches in State water quality programs (see Appendix R). Specifically, each of these three methods can provide avalid assessment of m wmenf of designated aquatic life uses but can rarely demonstrate use attainment separately. Therefore, EPA supports apolicy of independent application ofthesethree water quality assessment

3-12 (lv15194)Chapter 3-WaterQuality Crirm’a

approaches. Independent application means that the validity of the results of any one of the approaches does not depend on confirmation by
one or both of the other methods. This policy is based on the unique attributes, limitations, and program applications of each of the three approaches. Each method alone canprovide valid and independently sufficient evidence of nonattainment ofwater quality standards, irrespective of anyevidence, or lack thereof, derived from the other two approaches. The failure ofone method to confirm impacts identified by another method does not negate the results of the initial assessment.

It is also EPA’s policy that States should designate aquatic life uses that appropriately address biological integrity and adopt biological criteria necessary to protect those uses (see section 3.5.3 and Appendices C, K, and R).

cl 

### 3.4 Criteria for Toxicants

Applicable requirements for State adoption of water quality criteria for toxicants vary depending upon the toxicant. The reason for this isthat the 1983 Water Quality Standards Regulation (Appendix A) and theWater Quality Act of 1987 which amended theClean Water Act (Public Law 100-4) include more specific requirements for the particular toxicants listed pursuant to CWA section 307(a). For regulatory purposes, EPA has translated the 65 compounds and families of compounds listed pursuant to section 307(a) into 126 more specific substances, which EPA refers toas“priority toxic pollutants.” The 126priority toxic pollutants are listed in the WQS regulation and in Appendix Pofthis Handbook. Becauseof the more specific requirements for priority toxic pollutants* it is convenient to organize the requirements applicable to State adoption of criteria for toxicants into three categories:

a requirements applicable to priority toxic pollutants that havebeenthesubject ofCWA section 304(a)(l) criteria guidance (see section 3.4.1); l requirements applicable to priority toxic pollutants that have not been the subject of CWA section 304(a)( 1)criteria guidance (see section 3.4.1); and

0 requirements applicable toall other toxicants (e.g., non-conventional pollutants like ammonia and chlorine) (seesection 3.4.2).



### 3.4.1 Priority Toxic Pollutant Criteria

The criteria requirements applicable to priority toxic pollutants (i.e., the first two categories above) arespecified inCWA section 303(c)(2)(B). Section 303(c)(2)(B), as added by the Water Quality Act of 1987, provides that:

Whenever aStatereviews water quality standards pursuant to paragraph (1) of this subsection, or revises or adopts
new standards pursuant to this paragraph 1 such State shall adopt criteria for all toxic pollutants listed pursuant tosection 307(a)( 1)ofthis Act for which criteria have been published under section 304(a), the discharge or presence of which in the affected waters could reasonably beexpected to interfere with those designated uses adopted by the State, as necessary to support such designated uses. Such criteria shall be specific numerical criteria for such toxic pollutants. Where such numerical criteria are not available, whenever a State reviews water quality standards pursuant to paragraph (I), or revises oradopts new standards pursuant to this paragraph, such Stateshall adopt criteria basedon biological monitoring or assessment methods consistent with information published pursuant tosection 304(a)(8). Nothing in this section shall be construed to limit or delay the use of effluent limitations or other permit conditions based on or involving biological monitoring or assessment

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methods or previously adopted numerical criteria.

EPA, in devising guidance for section 303(c)(2)(B), attempted toprovide Stateswith the maximum flexibility that complied with the express statutory language but also with the overriding congressional objective: prompt adoption and implementation of numeric toxics criteria. EPA believed that flexibility was important so that each State could comply with section 303(c)(2)(B) and to the extent possible, accommodate its existing water quality standards regulatory approach.



### General Requirements

To carry out the requirements of section 303(c)(2)(B), whenever aState revises its water quality standards, it must review all available information and data to first determine whether thedischarge or the presence of atoxic pollutant isinterfering with or islikely tointerfere with the attainment of the designated uses of any water body segment.

If the data indicate that it is reasonable toexpect the toxic pollutant to interfere with the use,or it actually isinterfering with the use, then the State must adopt a numeric limit for the specific pollutant. If a State is unsure whether atoxic pollutant is interfering with, or is likely to interfere with, thedesignated useandtherefore is unsure thatcontrol ofthepollutant isnecessary to support the designated use, the State should undertake todevelop sufficient information upon which tomakesuchadetermination. Presence of facilities that manufacture or use the section 307(a) toxic pollutants or other information indicating that such pollutants are discharged or will be discharged strongly suggests that such pollutants could be interfering with attaining designated uses. If aState expects the pollutant not to interfere with the designated use, then section 303(1)(2)(B) does not require a numeric standard for that pollutant.

Section 303(c)(2)(B) addresses only pollutants listed as“toxic” pursuant tosection 307(a) of the Act, which are codified at 40 CFR 131.36(b). Thesection 307(a) list contains 65compounds and families of compounds, which potentially include thousands of specific compounds. The Agency hasinterpreted that list to include 126 “priority” toxic pollutants for regulatory purposes. Reference in this guidance to toxic pollutants or section 307(a) toxic pollutants refers to the 126 priority toxic pollutants unless otherwise noted. Both the list of priority toxic pollutants and recommended criteria levels aresubject tochange.

The national criteria recommendations published by EPA under section 304(a) (see section 3.1, above) of the Act include values for both acute and chronic aquatic life protection; only chronic criteria recommendations have beenestablished to

3-14 (8115194)Chapter 3-WaterQualitv Criteria

protect human health. To comply with the statute, a State needs to adopt aquatic life and human health criteria where necessary tosupport the appropriate designated uses. Criteria for the protection of human health are needed for water bodies designated for public water supply. When fish ingestion isconsidered animportant activity, then the human health-related water quality criteria recommendation developed under section 304(a) of the CWA should be used; that is, the portion of the criteria recommendation based on fish consumption. For thosepollutants designated
ascarcinogens, the recommendation for ahuman health criterion is generally more stringent than the aquatic life criterion for the same pollutant. In contrast, the aquatic life criteria recommendations for noncarcinogens are generally more stringent than the human health recommendations. When aStateadopts ahuman health criterion for acarcinogen, theState needs to select a risk level. EPA has estimated risk levels of 10-5, 10d6,and IO-’ in its criteria documents under onesetofexposure assumptions. However, the State is not limited to choosing among the risk levels published in the section 304(a) criteria documents, nor istheStatelimited to the base case exposure assumptions; it must choose therisk level for itsconditions andexplain its rationale.

EPA generally regulates pollutants treated as carcinogens in the range of lob to lo4 toprotect average exposed individuals and more highly exposed populations. However, if aStateselects
a criterion that represents an upper bound risk level lessprotective than I in 100,000 (e.g., lo’), the State needs to have substantial support in the record for this level. This support focusesontwo distinct issues. First, the record must include documentation that thedecision maker considered thepublic interest oftheStateinselecting therisk level, including documentation of public participation in the decision making process as required by the Water Quality Standards Regulation at 40 CFR 131.20(b). Second, the record must include ananalysis showing that the risk level selected, when combined with other risk assessment variables, isabalanced andreasonable estimate of actual risk posed, based on the best and most representative information available. The importance of the estimated actual risk increases as the degree of conservatism in the selected risk level diminishes. EPA carefully evaluates all assumptions used by a State if the Statechose toalter any one of the standard EPA assumption values (57 F.R. 60864, December 22, 1993).

EPA does not intend to propose changes to the current requirements regarding thebasesonwhich
a State can adopt numeric criteria (40 CFR 13I,II(b)(1)). Under EPA’s regulation, in addition to basing numeric criteria on EPA’s section 304(a) criteria documents, Statesmayalso base numeric criteria on site-specific determinations or other scientifically defensible methods.

EPA expects each State to comply with the neu statutory requirements inany section 303(c) water quality standards review initiated after enactment of theWater Quality Act of 1987. The structure of section 303(c) is to require States to review their water quality standards at least once each 3 year period. Section 303(c)(2)(B) instructs States to include reviews for toxics criteria whenever they initiate atriennial review. Therefore, even if aStatehascomplied with section 303(c)(2)(B), theStatemust review itsstandards eachtriennium to ensure that section 303(c)(2)(B) requirements continue to be met, considering that EPA may have published additional section 304(a) criteria documents and that the State will have new information on existing water quality and on pollution sources.

Itshould benoted that nothing intheAct orinthe Water Quality Standards Regulation restricfs the right of aStatetoadopt numeric criteria for any pollutant not listed pursuant to section 307(a)(l), and that such criteria may he expressed as concentration limits for anindividual pollutant or for a toxicity parameter itself as measured by whole-effluent toxicity testing. However, neither numeric toxic criteria nor whole-effluent toxicity

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should beusedasasurrogate for, ortosupersede theother.



### State Options

Statesmay meettherequirements ofCWA section 303(c)(2)(B) by choosing one of three scientifically and technically sound options (or
somecombination thereof): 

## (1)

(2)

(3) Adopt statewide numeric criteria in State water quality standards for all section 307(a) toxic pollutants for which EPA has developed criteria guidance, 

### regardless of whether the pollutants are known to be present;
Adopt specific numeric criteria in State water quality standards for section 307(a) toxic pollutants as necessary to support designated uses where such poilutants are discharged or are present in the affected waters and could reasonably beexpected to interfere with designated uses;
Adopt a“translator procedure” tobeapplied to a narrative water quality standard provision that prohibits toxicity in receiving waters. Such a procedure is to be used by the State in calculating derived numeric criteria, which shall beusedfor all purposes under section 303(c) of the CWA. At a minimum, suchcriteria needtobedeveloped for section 307(a) toxic pollutants, as necessary tosupport designated uses,where these pollutants are discharged or present in the affected waters and could reasonably be expected to interfere with designated uses,
Option I is consistent with State authority to establish water quality standards. Option 2most directly reflects theCWA requirements andisthe option recommended by EPA. Option 3, while meeting the requirements of the CWA, is best suited tosupplement numeric criteria from option I or 2. The three options are discussed in more detail below. 

### OFmON 1
Adopt statewide numeric criteria inStatewater quality standards for all section 307(a) toxic polh~tantsfor which EPA hasdeveloped criteria guidance, regardless ofwhether the pollutants
am known tobepresent.

Pro:

l simple, straightfonvard implementation

l ensures that Stateswill satisfy statute

l makes maximum uses of EPA recommendations

0 getsspecific numbers into Statewater quality standards fast, atfirst

Con:

a some priority toxic pollutants may not be discharged in State

a maycauseunnecessary monitoring byStates

0 might result in “paper standards”
Option I iswithin aState’s legal authority under theCWA toadopt broad water quality standards. This option isthe most comprehensive approach to satisfy the statutory requirements because it would include all of the priority toxic pollutants for which EPA has prepared section 304(a) criteria guidance for either or both aquatic life protection and human health protection. In addition to asimple adoption of EPA’s section 304(a) guidance asstandards, aState must select
arisk level for those toxic pollutants which are carcinogens (i.e., that causeor may cause cancer in humans).
Many Statesfind this option attractive because it
ensures comprehensive coverage of the priority toxic pollutants with scientifically defensible criteria without the need to conduct a resourceintensive evaluation oftheparticular segments and

3-16 (8’15’94)Chaprer 3-WaterQuality Criteria

pollutants requiring criteria. This option also would not be more costly to dischargers than other options because permit limits would be based only on the regulation of the particular toxic pollutants in their discharges and not onthe total listing in thewater quality standards. Thus, actual permit limits should bethesameunder any of the options.

The State may also exercise its authority to use oneor more ofthetechniques for adjusting water quality standards:

8 establish or revise designated stream uses based on use attainability analyses (see section 2.9);

l develop site-specific criteria; or

0 allow short-term variances (seesection 5.3) when appropriate.

All three of these techniques may apply to standards developed under any of the three options discussed in this guidance. It is likely that Stateselecting to useoption 1will rely more
on variances because the other two options are implemented with more site-specific data being available. It should be noted, however, that permits issued pursuant to such water quality variances still must comply with any applicable antidegradation andantibacksliding requirements.



### OITION 2
Adopt specific numeric criteria in State water quality standards for section 307(a) toxic pollutants as necessary to support designated
useswhere such pollutants are discharged or are present in the affected waters and could reasonably be expected to interfere with designated uses.

Pro:

l directly reflects statutory requirement l standards based on demonstrated need to control problem pollutants

l Statecan useEPA’s section 304(a) national criteria recommendations or other scientificallyacceptablealtemative, including site-specific criteria

l Statecan consider current or potential toxic pollutant problems

l State can go beyond section 307(a) toxics list, asdesired

Con:

may be difficult and time consuming to determine if, and which, pollutants are interfering with the designated use
adoption of standards can require lengthy debates on correct criteria limit to be included in standards

successful Statetoxic control programs based
onnarrative criteria may behalted orslowed
asthe State applies its limited resources to developing numeric standards

difficult to update criteria once adopted as part of standards

to beabsolutely technically defensible, may needsite-specific criteria in many situations, leading to a large workload for regulatory agency

EPA recommends that aState usethis option to meetthestatutory requirement. Itdirectly reflects all the Act’s requirements and is flexible, resulting in adoption of numeric water quality standards asneeded. To assure that the State is capable of dealing with new problems as they arise, EPA also recommends that States adopt a translator procedure the same as, or similar to, that described in option 3, but applicable to all chemicals causing toxicity and not just priority pollutants asisthecasefor option 3.

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Beginning in 1988, EPA provided States with candidate lists of priority toxic pollutants and water bodies in support of CWA section 304(l) implementation. These lists were developed because States were required toevaluate existing andreadily available water-related datatocomply with section 304(l), 40CFR 130.10(d). Asimilar “strawman” analysis of priority pollutants potentially requiring adoption of numeric criteria under section 303(c)(2)(B) was furnished to most States in September or October of 1990 for their
usein ongoing and subsequent triennial reviews. The primary differences between the “strawman” analysis andthesection 304(l) candidate listswere that the “strawman” analysis (I) organized the results bychemical rather than bywater body, (2) included data for certain STORET monitoring stations that were not used in constructing the candidate lists, (3) included data from theToxics Release Inventory database, and (4) did not include a number of data sources used in preparing the candidate lists (e.g., those, suchas fish kill information, that did not provide chemical-specific information).

EPA intends for States, ataminimum, tousethe information gathered in support of section 304(l) requirements asastarting point for identifying (1) water segments that will need new and/or revised water quality standards for section 307(a) toxic pollutants, and (2) which priority toxic pollutants require adoption of numeric criteria. In the longer term, EPA expects similar determinations to occur during each triennial review of water quality standards asrequired by section 303(c).

In identifying the need for numeric criteria, EPA isencouraging Statesto useinformation anddata such as:

l presence or potential construction of facilities that manufacture or use priority toxic pollutants;

l ambient water monitoring data, including thosefor sediment andaquatic life (e.g., fish tissue data); NPDES permit applications and permittee self-monitoring reports;

effluent guideline development documents, many of which contain section 307(a)(l) priority pollutant scans;
pesticide and herbicide application information andother records ofpesticide or herbicide inventories;
public water supply source monitoring data noting pollutants with Maximum Contaminant Levels (MCLs); and

any other relevant information on toxic pollutants collected by Federal, State, interstate agencies, academic groups, or scientific organizations.

States are also expected to take into account
newer information asit became available, suchas information in annual reports from the Toxic Chemical Release Inventory requirements of the Emergency Planning and Community Right-ToKnow Act of 1986(Title III, Public Law 99-499).

Where the State’s review indicates a reasonable expectation of a problem from the discharge or presence of toxic pollutants, the State should identify the pollutant(s) and the relevant segment(s). In making these determinations, Statesshould usetheir own EPA-approved criteria
or existing EPA water quality criteria for purposes of segment identification. After the review, theStatemay useother meanstoestablish the final criterion asit revises its standards.

As with option 1, a State using option 2 must follow all its legal and administrative requirements for adoption of water quality standards. Sincetheresulting numeric criteria are part of aState’s water quality standards, they are required to besubmitted by the State to EPA for review andeither approval or disapproval.

EPA believes this option offers theStateoptimum flexibility. For section 307(a) toxic pollutants

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adversely affecting designated uses, numeric criteria areavailable for permitting purposes. For other situations, the State has the option of defining site-specific criteria.

OPTION 

### 3
Adopt a procedure to be applied to the narrative water quality standard provision that prohibits toxicity in receiving waters. Such a procedure would be used by a State in calculating derived numeric criteria tobeused for all purposes ofwater quality criteria under section 303(c) of the CWA. At a minimum such criteria need to be derived for section 307(a) toxic pollutants where the discharge or presence of such pollutants in the affected waters could reasonably be expected to interfere with designated uses,asnecessary to support such designated uses.

Pro:

allows aState flexibility to control priority toxic pollutants

reduces time and cost required to adopt specific numeric criteria as water quality standards regulations

allows immediate use of latest scientific information available at the time a State needs todevelop derived numeric criteria

revisions and additions to derived numeric criteria can be made without need to revise State law

State can deal more easily with asituation where it did not establish water quality standards for the section 307(a) toxic pollutants during the most recent triennial review

Statecanaddress problems from non-section 307(a) toxic pollutants Con:

0 EPA is currently on notice that aderived numeric criterion may invite legal challenge

a oncethenecessary procedures areadopted to enhance legal defensibility (e.g., appropriate scientific methods and public participation andreview), actual savings in time andcosts may belessthan expected

l public participation in development of derived numeric criteria may be limited when such criteria are not addressed in a hearing on water quality standards

EPA believes thatadoption ofanarrative standard along with atranslator mechanism as part of a State’s water quality standard satisfies the substantive requirements of the statute. These criteria are subject to all the State’s legal and administrative requirements for adoption of standards plus review and either approval or disapproval by EPA, and result in the development of derived numeric criteria for specific section 307(a) toxic pollutants. They are also subject to an opportunity for public participation. Nevertheless, EPA believes the most appropriate use of option 3 is as a supplement toeither option 1or2. Thus, aState would have formally adopted numeric criteria for toxic pollutants that occur frequently; that have general applicability statewide for inclusion in NPDES permits, total maximum daily loads, and waste load altocations; and that also would have
a sound and predictable method to develop additional numeric criteria as needed. This combination of options provides a complete regulatory scheme.
Although the approach in option 3 is similar to that currently allowed in the Water Quality Standards Regulation (40 CFR 131.1l(a)(2)), this guidance discusses several administrative and scientific requirements that EPA believes are necessary tocomply with section 303(c)(2)(B).

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### (1) TheOption 3Procedure Must BeUsedTo Calculate Derived Numeric Water Quality Criteria

States must adopt a specific procedure to be applied toanarrative water quality criterion. To satisfy section 303(c)(2)(B), this procedure shall be used by the State in calculating derived numeric criteria, which shall be used for all purposes under section 303(c) oftheCWA. Such criteria need to be developed for section 307(a) toxic pollutants asnecessary tosupport designated uses,where thesepollutants aredischarged orare present in the affected waters and could reasonably be expected to interfere with the designated uses.

To assure protection from short-term exposures, theStateprocedure should ensure development of derived numeric water quality criteria based on valid acute aquatic toxicity teststhat are lethal to half theaffected organisms (LC50) for thespecies representative of or similar tothose found in the State. In addition, the State procedure should
ensure development of derived numeric water quality criteria for protection from chronic exposure by using an appropriate safety factor applicable to this acute limit. If there are saltwater components to the State’s aquatic resources, the State should establish appropriate derived numeric criteria for saltwater in addition tothose for freshwater.

The State’s documentation of the tests should include adetailed discussion of itsquality control and quality assurance procedures. The State should also include a description (or reference existing technical agreements with EPA) of the procedure it will use to calculate derived acute and chronic numeric criteria from the test data, and how thesederived criteria will beusedasthe basis for deriving appropriate TMDLs, WLAs, and NPDES permit limits.

Asdiscussed above, theprocedure for calculating derived numeric criteria needs to protect aquatic life from both acute and chronic exposure to specific chemicals. Chronic aquatic life criteria are to be met at the edge of the mixing zone. The acute criteria aretobemet (1) attheend-ofpipe if mixing is not rapid and complete and a high rate diffuser is not present; or (2) after mixing if mixing 

### israpid and complete or ahigh rate diffuser is present. (See EPA’s 

### Technical SupponDocumentfor War4rQuality-based Toxics Control, USEPA 1991a.)

EPA has not established a national policy specifying thepoint ofapplication inthereceiving water to be used with human health criteria. However, EPA hasapproved Statestandards that apply human health criteria for fish consumption at the mixing zone boundary and/or apply the criteria for drinking water consumption, at a minimum, at the point of use. EPA has also proposed more stringent requirements for the application of human health criteria for highly bioaccumulative pollutants in the 

### Wafer Qualify guidance for flu Great L.&es System (50 F.R. 20931, 21035, April 16, 1993) including elimination of mixing zones.

In addition, the State should also include an indication of potential bioconcentration or bioaccumulation by providing for:

l laboratory teststhat measure thesteady-state bioconcentration rate achieved by a susceptible organism; and/or

l field data in which ambient concentrations and tissue loads are measured to give an appropriate factor.

In developing a procedure to be used in calculating derived numeric criteria for the protection of aquatic life, the State should consider thepotential impact thatbioconcentration hasonaquatic and terrestrial food chains.

The State should also use the derived bioconcentration factor and food chain multiplier tocalculate chronically protective numeric criteria for humans that consume aquatic organisms. In calculating this derived numeric criterion, the Stateshould indicate data requirements to bemet

3-20 (8115194)Chapter 3-WarmQuality Crimia

when dealing with either threshold (toxic) ornonthreshold (carcinogenic) compounds. The State should describe the species and the minimum number of tests, which may generally be met by
asingle mammalian chronic test if it is of good quality andiftheweight ofevidence indicates that the results are reasonable. The State should provide themethod tocalculate aderived numeric criterion from the appropriate test result.

Both the threshold and non-threshold criteria for protecting human health should contain exposure assumptions, and the State procedure should be used to calculate derived numeric criteria that address theconsumption ofwater, consumption of fish, and combined consumption of both water and fish. The State should provide the assumptions regarding theamount of fish andthe quantity of water consumed per person per day,
as well as the rationale used to select the assumptions. It needs to include the number of tests, the species necessary to establish adoseresponse relationship, and the procedure to be used to calculate the derived numeric criteria. For non-threshold contaminants, the Stateshould specify the model usedtoextrapolate tolow dose and the risk level. It should also address incidental exposure from other water sources (e.g., swimming). When calculating derived numeric criteria for multiple exposure to pollutants, the State should consider additive effects, especially for carcinogenic substances, and should factor in the contribution tothedaily intake of toxicants from other sources (e.g., food, air) when data are available.
(2) The State 

### Must Demonstrate That the Procedure 

### Results in Derived Numeric Criteria Are Protective

The Stateneedstodemonstrate that itsprocedures for developing criteria, including translator methods, yield fully protective criteria for human health andfor aquatic life. EPA’s review process will proceed according to EPA’s regulation of40 CFR 131.11, which requires thatcriteria bebased
on sound scientific rationale and beprotective of all designated uses. EPA will usethe expertise andexperience it hasgained indeveloping section 304(a) criteria for toxic pollutants by application of its own translator method ([JSEPA, 1980b; USEPA, 1985b).

Once EPA has approved the State’s procedure, the Agency’s review of derived numeric criteria, for example, for pollutants other than section 307(a) toxic pollutants resulting from the State’s procedure, will focus ontheadequacy of thedata base rather than the calculation method. EPA also encourages Statesto apply such aprocedure tocalculate derived numeric criteria tobeusedas the basis for deriving permit limitations for nonconventional pollutants that also cause toxicity.


### (3) The State Must Provide Full Opportunity for Public Participation inAdoption ofthe Procedure

The Water Quality Standards Regulation requires Statestohold public hearings toreview andrevise water quality standards in accordance with provisions of State law and EPA’s Public Participation Regulation (40 CFR 25). Where a State plans to adopt aprocedure to beapplied to the narrative criterion, it must provide full opportunity for public participation in the development andadoption oftheprocedure aspart of the State’s water quality standards.

While it is not necessary for the State to adopt each derived numeric criterion into its water quality standards andsubmit itto EPA for review and approval, EPA is very concerned that all affected parties have adequate opportunity to participate in the development of a derived

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numeric criterion even though it is not being adopted directly asawater quality standard.

A State can satisfy the need to provide an opportunity for public participation in the development ofderived numeric criteria inseveral ways, including:

0 a specific hearing on the derived numeric criterion;

l the opportunity for a public hearing on an NPDES permits as long aspublic notice is given that acriterion for atoxic pollutant as part of the permit issuance is being contemplated; or

l ahearing coincidental with anyother hearing
aslong asit is made clear that development of a specific criterion is also being undertaken.

For example, as States develop their lists and individual control strategies (ICSs) under 

### section 304(1), they may seek full public participation. NPDES regulations also specify public participation requirements related toState permit issuance. Finally, Stateshave public participation requirements associated with Water Quality Management Plan updates. States may take advantage of any of these public participation requirements to fulfill the requirement for public review of any resulting derived numeric criteria. Insuchcases,theStatemustgive prior notice that development of such criteria is under consideration.


### (4) The Procedure Must BeFormalIy Adopted and Mandatory

Where aState elects to supplement its narrative criterion with an accompanying implementing procedure, it must formally adopt such a procedure asapart of its water quality standards. The procedure must be used by the State to calculate derived numeric criteria thatwill beused
asthebasis for all standards’ purposes, including the following: developing TMDLs, WLAs, and limits in NPDES permits; determining whether water use designations are being met; and identifying potential nonpoint source pollution problems. 

### (5’) The Procedure Must BeApproved byEPA
as Part of the State’s Water Quality Standards Regulation

To beconsistent with therequirements oftheAct, theState’sprocedure tobeapplied tothenarrative criterion must be submitted to EPA for review and approval, and will become a part of the State’s water quality standards. (See 40 CFR 131.21 for further discussion.) This requirement maybesatisfied byareference inthestandards to theprocedure, which maybecontained inanother document, which has legal effect and is binding
on the State, and all the requirements for public review, State implementation, and EPA review andapproval aresatisfied.



### Criteria Basedon Biological Monitoring

For priority toxic pollutants for which EPA has not issued 

### section 304(a)( 1) criteria guidance, CWA section 303(c)(2)(B) requires Statestoadopt criteria based on biological monitoring or assessment methods. The phrase “biological monitoring orassessment methods” includes:

l whole-effluent toxicity control methods;

l biological criteria methods; or

l other methods based on biological monitoring or assessment.

The phrase “biological monitoring or assessment methods” in its broadest sense also includes criteria developed through translator procedures. This broad interpretation of that phrase is consistent with EPA’s policy of applying chemical-specific, biological, and whole-effluent toxicity methods independently in an integrated toxics control program. It isalso consistent with the intent of Congress to expand State standards programs beyond chemical-specific approaches.

3-22 (8/15/94)Chaprer3-Wurrr Qutrlm Crileriu

States should also consider developing protocols to derive and adopt nurncric criteria for priority toxic pollutants; (or other pollutants) where EPA has not issued sccticjn 304(a) criteria guidance. The S(ate should consider available laboratory toxicity testdatathat maybesufficient tosupport derivation of chemical-specific criteria. Existing data nwd not be as comprehensive as that required to meet EPA’s 1985guidelines in order for a State to use its own protocols to derive criteria. EPA hasdescribed such protocols inthe proposed 

### Wult’r Qlctrliiy Guiilunw for Ih4 Great Lakes .Y~.sff*m

(38 f:.R. 20892. at21016, April 16, 1993.) This isparticularly important where other components of a Stitc’s narrative criterion implementation proccdl.re (e.g., WET controls or biological criteria) may not ensure full protection of designated uses. f:or some pollutants, a combination of chemical-specific and other approaches ISncccssary (e.g., pollutants where bioaccumulation in fish tissue or water consumption by humans isaprimary concern).
Biologically based monitoring or assessment methods serve asthe basis for control where no specific numeric criteria exist orwhere calculation
or application of pollutant-by-pc~llutant criteria appears int‘cdsiblc. Also, the.se methods may serve as a supplemental measurement of attainment of water quality standards in addition to numeric and narratlvc criteria. The requirement for both numeric criteria and biologically based methods demonstrates that section 303(c)( 2j(B) contemplates that States develop acomprehensi\,e toxics control program regardless of the status of EPA’s section 304(a) criteria.

The whole-effluent toxicity (WET) testing procedure is the principal biological monitoring guidance developed by EPA todate. The purpose of the WET procedure istocontrol point source dischargers of toxic pollutants. The procedure is particularly useful for monitoring and controlling the toxicity of complex effluents that may not be well controlled through chemical-specific numeric criteria. As such, biologically based effluent testing procedures are anecessary component of a State’s toxics control program under section 303(c)(2)(B) and a principal means for implementing a State’s narrative “free from toxics” standard.

Guidance documents EPA considers to serve the purpose ofsection 304(a)(8) include the

### Technical SupportDocumerufr,r WuterQuulif)-bused ToxicJ Control (USEPA, 1991 a;

### Guiddines jiv Deriviq Nationul WaterQuulity Criteriu.fiv rheProtecrion ofAquuric Organisms and Their Uses(Appendix H); 

### Guidelines and Merhodolqqv Usd in the Preparabon ofHealth EflecrAs.ses.snwrrChapters oftheCement Decree WaterCrireriu Documenrs (Appendix 

### 1); Methods fiv Meusuring Awe Toxicity of Efluenrs to Freshwarer unclMarine Organisms (USEPA, 199Id); 

### Short-TermMethods $v Esrimaring the Chronic Ttsriciry 

## rrfEfluenrs and Receiving Watersto Fw.sh\rwer 0r~unism.s (USEPA, 199le); and 

### Shon-Term Mrrhtds /iv Esrimaring sheChronic Toxicir?*04‘IZfluenrs and Receiving Waters 10 Murinc und Emarine Organisms (USEPA, 19910.



### 3.4.2 Criteria for Nonconventional Pollutants

Criteria requirements applicable to toxicants that
are not priority toxic pollutants (e.g.. ammonia and chlorine), are specified in the 1983 Water Quality Standards Regulation (see 40 CFR 131.11). Under these requirements, States must adopt criteria based on sound scientific rationale that cover sufficient parameters to protect designated uses. Both numeric and narrative criteria (discussed in sections 3.5.1 and 3.5.2, below) may be applied to meet these requirements.

cl 

### 3.5 Forms ofCriteria

Statesarerequired toadopt water quality criteria, based on sound scientific rationale, that contain sufficient parameters orconstituents toprotect the designated use. EPA believes that an effective State water quality standards program should include both parameter-specific (e.g., ambient numeric criteria) and narrative approaches.

(8/15/94) 

### 3-23WaterQuality StandardsHandbook -SecondEd&on



### 3.5.1 Numeric Criteria

Numeric criteria are required where necessary to protect designated uses. Numeric criteria to protect aquatic life should bedeveloped toaddress both short-term (acute) and long-term (chronic) effects. Saltwater species, aswell asfreshwater species, must beadequately protected. Adoption of numeric criteria is particularly important for toxicants known to be impairing surface waters and for toxicants with potential human health impacts (e.g., those with high bioaccumulation potential). Human health should be protected from exposure resulting from consumption of water andfish orother aquatic life (e.g., mussels, crayfish). Numeric water quality criteria alsoare useful in addressing nonpoint source pollution problems.

In evaluating whether chemical-specific numeric criteria for toxicants that are m priority toxic pollutants are required, States should consider whether other approaches (such aswhole-effluent toxicity criteria orbiological controls) will ensure full protection of designated uses. 

### Asmentioned above, acombination of independent approaches may be required in some cases to support the designated usesandcomply with therequirements of the Water Quality Standards Regulation (e.g., pollutants where bioaccumulation in fish tissueor water consumption by humans is a primary concern).



### 3.5.2 Narrative Criteria

To supplement numeric criteria for toxicants, all States have also adopted narrative criteria for toxicants. Such narrative criteria are statements that describe the desired u’ater quality goal, such
asthe following:

All waters, including those within mixing zones, shall be free from substances attributable to wastewater discharges or other pollutant sources that: Settle to form objectional deposits:

Float as debris, scum, oil, or other matter forming nuisances;

Produce objectionable color, odor, taste, or turbidity;

Cause injury to, or are toxic to,
or produce adverse physiological responses in humans, animals, or plants; or

Produce undesirable or nuisance aquatic life (54 F.R. 28627, July 6, 1989).

EPA considers that the narrative criteria apply to all designated usesatall flows and are necessary to meet the statutory requirements of section 

### 303(c)(2)(A) of the

### CWA.

Narrative toxic criteria (No. 4, above) can bethe basis for establishing chemical-specific limits for wastedischarges where aspecific pollutant canbe identified ascausing orcontributing tothetoxicity and the State has not adopted chemical-specific numeric criteria. Narrative toxic criteria arecited
asabasis for establishing whole-effluent toxicity controls in EPA permitting regulations at40CFR 122.44(d)(l)(v).

To ensure that narrative criteria for toxicants are attained, theWater Quality Standards Regulation requires States to develop implementation procedures (see 40 CFR 131.Il(a)(2)). Such implementation procedures (Exhibit 3-3) should address all mechanisms tobeusedby theStateto
ensure that narrative criteria are attained. Because implementation of chemical-specific numeric criteria is a key component of State toxics control programs, narrative criteria implementation procedures must describe or reference the State’s procedures to implement such chemical-specific numeric criteria (e.g., procedures for establishing chemical-specific permit limits under the NPDES permitting

(8115194)Chuprn 3-Wa~crQuality Critcrio

State implementation procedures for narrative toxics criteria should describe the following:

8 Specific, scientifically defensible methods bywhich theStatewill implement itsnarrative toxics 

### standard for all toxicants, including:

- methods forchemical-specific criteria, including methods for applying chemical-specific criteria in

### permits, developing or modifying chemical-specific criteria via a“translator procedure” (defined and discussed below), and calculating site-specific criteria based
on local water chemistry or biology);

- methods for developing and implementing whole-effluent toxicity criteria and/or controls; and

- methods for developing and implementing biological criteria.

l How these methods will beintegrated intheState’s toxics control program (i.e., how the Statewill proceed when thespecified methods produce conflicting orinconsistent results).

l Application criteria and information 

### neededtoapply 

### numerical criteria, for example:

- methods the State will useto identify those pollutants to be regulated in aspecific discharge;

- an incremental cancer risk level for carcinogens:

- methtis for identifying compliance thresholds in permits where calculated limits are below detection;

- methods for selecting appropriate hardness, pH, andtemperature variables for criteria expressed asfunctions;

- methods or policies controlling thesizeand in-zone quality of mixing zones;

- design flows tobeusedin translating chemical-specific numeric criteria for aquatic life and human health into permit limits; and

- other methods 

### andinformation needed toapply standards on acase-by-case basis.



### Exhibit 3-3. Components ofaState Implementation Procedure for Narrative Toxics Criteria

(8f15f94) 

### 3-25H’utrr Oulltv StandardsHandhook -SecondEdition

program). Implementation procedures must also address State programs to control whole-effluent toxicity (WET) and may address programs to implement biological criteria, where such programs have been developed by the State. Implementation procedures therefore serve as umbrella documents that describe how theState’s various toxics control programs are integrated to
ensure adequate protection for aquatic life and human health and attainment of the narrative toxics criterion. Inessence, theprocedure should apply the “independent application” principle, which provides for independent evaluations of attainment ofadesignated usebased

### onchemicalspecific, whole-eftluent toxicity, and biological criteria methods (see section 3.5.3 and Appendices C. K. and R).

EPA encourages, and may ultimately require, State implementation procedures to provide for implementation of biological criteria. However, the regulatory basis for requiring whole-effluent toxicity (WET) controls isclear. EPA regulations at 40 CFR 122.44(d)(l)(v) require NPDES permits tocontain WET limits where apermittee has been shown to cause, have the reasonable potential to cause, or contribute to an in-stream excursion ofanarrative criterion. Implementation of chemical-specific controls is also required by EPA regulations at40 CFR 122.44(d)(l). State implementation procedures should, ataminimum, specify or reference methods to be used in implementingchemical-specificand whole-effluent toxicity-based controls, explain how these methods are integrated, and specify needed application criteria.

In addition to EPA’s regulation at40 CFR 131, EPA hasregulations at40CFR 122.44 thatcover the National Surface Water Toxics Control Program. These regulations are intrinsically linked to the requirements to achieve water quality standards, and specifically address the control of pollutants both with and without
nurneric criteria. For example, section 12?.44(d)( l)(vi) provides thepermitting authority with several options forestablishing effluent limits when a State does not have achemical-specific numeric criterion for a pollutant present in an effluent at a concentration that causes or contributes to aviolation of the State’s narrative criteria.



### 3.5.3 Biological Criteria

The Clean Water Act of 1972 directs EPA to develop programs that will evaluate, restore, and maintain the chemical, physical, and biological integrity of the Nation’s waters. In response to this directive, Statesand EPA have implemented chemically based water quality programs that address significant water pollution problems. However, over the past 20 years, it has become apparent thattheseprograms alone cannot identify andaddress all surface water pollution problems. To help create a more comprehensive program, EPA issetting apriority for the development of biological criteria as part of State water quality standards. This effort will help States and EPA (1)achieve thebiological integrity objective ofthe CWA set forth in section 101, and (2) comply with thestatutory requirements under sections 303 and 304of the Act (seeAppendices Cand K).


### Regulatory Basesfor Biocriteria

The primary statutory basis for EPA’s policy that States should develop biocriteria is found in sections 101(a) and 303(c)(2)(B) of the Clean Water Act. Section 101(a) oftheCWA gives the general goal of biological criteria. It establishes
as the objective of the Act the restoration and maintenance of the chemical, physical, and biological integrity of the Nation’s waters. To meet this objective, water quality criteria should address biological integrity. Section 101(a) includes the interim water quality goal for the protection and propagation of fish, shellfish, and wildlife.

Section 304(a) of theAct provides the legal basis for the development of informational criteria, including biological criteria. Specific directives for thedevelopment of regulatory biocriteria can befound insection 303(c), which requires EPA to develop criteria based on biological assessment

3-26 (8f15194)hlJpkT 3

- WlJJPT @JAcJlif~ CriJWifJ

methods when numerical criteria are not established.

Section 304(a) directs EPA todevelop andpublish water quality criteria and information on methods for measuring water quality andestablishing water quality criteria for toxic pollutants 

### onbasesother than pollutant-by-pollutant, including biological monitoring and assessment methods that assess:

l the effects of pollutants on aquatic community components (“.

. . plankton, fish, shellfish, wildlife, plant life

. . .“) and community attributes (“.

. . biological community diversity, productivity, and stability

. . .I’) in any body of water; and

0 factors necessary ”

. . . to restore and maintain the chemical, physical, and biological integrity of all navigable waters

.

. .” for ”

. . . the protection of shellfish, fish, and wildlife for classes and categories of receiving waters , . . .”

Once biocriteria are formally adopted into State standards, biocriteria and aquatic life use designations serve asdirect, legal endpoints for determining aquatic life use attainment/nonattainment. CWA section 303(c)(2)(B) provides that when numeric criteria are not available, States shall adopt criteria for toxics based on biological monitoring or assessment methods; biocriteria can be usedto meetthis requirement.


### Development and Implementation of Biocriteria

Biocriteria are numerical values or narrative expressions that describe the expected reference biological integrity of aquatic communities inhabiting waters of adesignated aquatic life use. In the most desirable scenario, these would be waters that are either in pristine condition or minimally impaired. However, in some areas these conditions no longer exist and may not be attainable. In these situations, the reference biological communities represent the best attainable conditions. Ineither case,thereference conditions then become the basis for developing biocriteria for major surface water types (streams, rivers, lakes. wetlands, estuaries, or marine waters).
Biological criteria support designated aquatic life
use classifications for application in State standards (seechapter 2). Each Statedevelops its
own designated useclassification system basedon thegeneric usescited in the Act (e.g., protection and propagation of fish, shellfish, and wildlife). Designated uses are intentionally general. However, States may develop subcategories within usedesignations to refine and clarify the
use class. Clarification of the use class is particularly helpful when a variety of surface waters with distinct characteristics fit within the
same use class. or do not fit well into any category.

For example, subcategories of aquatic life uses may be on the basis of attainable habitat (e.g., coldwater versus warmwater stream systems as represented by distinctive trout or bass fish communities, respectively). Special uses may also bedesignated to protect particularly unique, sensitive, or valuable aquatic species, communities, or habitats.

Resident biota integrate multiple impacts over time and candetect impairment from known and unknown causes. Biological criteria can beused to verify improvement in water quality in response to regulatory and other improvement efforts and to detect new or continuing degradation of waters. Biological criteria also provide a framework for developing improved best management practices and management
measures for nonpoint source impacts. Numeric biological criteria can provide effective monitoring criteria for more definitive evaluation of the health of anaquatic ecosystem.

The assessment of the biological integrity of a water body should include measures of the structure and function of the aquatic community within aspecified habitat. Expert knowledge of the system is required for the selection of

(8!15/94) 3-27WaterOuahtv StandardsHnndbcmk-SecandEdition

appropriate biological components and measurement indices. The development and implementation of biological criteria requires:

selection of surface waters to use in developing reference conditions for each designated use;

measurement ofthestructure andfunction of aquatic communities in reference surface waters toestablish biological criteria;

measurement of the physical habitat and other environmental characteristics of the water resource; and

establishment of a protocol to compare the biological criteria tobiota incomparable test waters todetermine whether impairment has occur-red.

These elements serve as an interactive network that is particularly important during early development of biological criteria where rapid accumulation of information is effective for refining both designated uses and developing biological criteria values and the supporting biological monitoring andassessment techniques.



### 3.54 Sediment Criteria

While ambient water quality criteria are playing
an important role in assuring a healthy aquatic environment, they alone have not been sufficient to ensure appropriate levels of environmental protection. Sediment contamination, which can involve deposition of toxicants over long periods of time, is responsible for water quality impacts in someareas.

EPA hasauthority to pursue the development of sediment criteria in streams, lakes and other waters oftheUnited Statesunder sections 104and 304(a)( 1)and (2) of the CWA asfollows:

l section 104(n)( 1) authorizes the Administrator toestablish national programs that study theeffects 

### of pollution, including sedimentation, in estuaries on aquatic life;

l section 304(a)( 1)directs theAdministrator to develop and publish criteria for water quality, including information on thefactors affecting rates of organic and inorganic sedimentation for varying types of receiving waters;

a section 304(a)(2) directs theAdministrator to develop and publish information on, among other issues, “the factors necessary for the protection andpropagation of shellfish, fish, and wildlife for classes and categories of receiving waters.

. , .”

To the extent that sediment criteria could be developed thataddress theconcerns ofthesection 404(b)( 1)Guidelines for discharges ofdredged or fill material under the CWA or the Marine Protection, Research, and Sanctuaries Act, they could also beincorporated into those regulations.

EPA’s current sediment criteria development effort, asdescribed below, focuses oncriteria for the protection of aquatic life. EPA anticipates potential future expansion of this effort toinclude sediment criteria for the protection of hurnan health.



### Chemical Approach to Sediment Criteria Development

Over the past several years, sediment criteria development activities havecentered onevaluating and developing the Equilibrium Partitioning Approach for generating sediment criteria. The Equilibrium Partitioning Approach focuses on predicting the chemical interaction between sediments and contaminants. Developing an understanding of the principal factors that influence the sediment/contaminant interactions will allow predictions to be made regarding the level of contaminant concentration that benthic andother organisms may beexposed to. Chronic water quality criteria, or possibly other toxicological endpoints, can then be used to

3-28 ;a115/94)Chapter 3-Wa~rrQualin, Criteria

predict potential biological effects. In addition to thedevelopment of sediment criteria, EPA isalso working to develop a standardized sediment toxicity test that could be used with or independently of sediment criteria to assess chronic effects in fresh and marine waters.


### Eguilibtium Partitioning (EqP) Sediment Quality C&e&2 (SQC) are the U.S. Environmental Protection Agency’s best recommendation of the concentration ofa substance in sediment that will not unacceptably qffect benthic organisms or their uses.
Methodologies for deriving effects-based SQC vary for different classes of compounds. For non-ionic organic chemicals, the methodology requires normalization to organic carbon. A methodology for deriving effects-based sediment criteria for metal contaminants is under development and is expected to require normalization to acid volatile sulfide. EqP SQC values can be derived for varying degrees of uncertainty and levels of protection, thus permitting use for ecosystem protection and remedial programs. 

### Application ofSediment Criteria

SQC would provide a basis for making more informed decisions on the environmental impacts of contaminated sediments. Existing sediment assessment methodologies are limited in their ability to identify chemicals of concern, responsible parties, degree ofcontamination, and
zones of impact. To make the most informed decisions, EPA believes that a comprehensive approach using SQC and biological test methods ispreferred.

Sediment criteria will be particularly valuable in site-monitoring applications where sediment contaminant concentrations are gradually approaching a criterion over time or as a preventive tool to ensure that point and nonpoint
sources of contamination are controlled and that uncontaminated sediments remain uncontaminated. Also comparison of field measurements to sediment criteria will be a reliable method for providing early warning of a potential problem. Anearly warning would provide anopportunity to take corrective action before adverse impacts
occur. For the reasons mentioned above, it has beenidentified that SQC areessential toresolving key contaminated sediment and source control issues in the Great Lakes. 

### Spec$c Applications
Specific applications of sediment criteria are under development. The primary use of FqPbased sediment criteria will be to assess risks associated with contaminants in sediments. The various offices and programs concerned with contaminated sediment have different regulatory mandates and, thus, have different needs and
areasforpotential application ofsediment criteria. Because each regulatory need is different, EqPbased sediment quality criteria designed specifically to meet the needs of one office or program may have tobeimplemented in different ways to meet the needs of another office or program.

One mode of application of FqP-based numerical sediment quality criteria would be in a tiered approach. In such an application, when contaminants in sediments exceed the sediment quality criteria thesediments would beconsidered
ascausing unacceptable impacts. Further testing may or may not be required depending on sitespecific conditions and the degree in which a criterion has been violated. (In locations where contamination significantly exceeds acriterion, no additional testing would be required. Where sediment contaminant levels are close to a criterion, additional testing might be necessary.) Contaminants inasediment atconcentrations less than the sediment criterion would not be of
concern. However, in some cases the sediment could not be considered safe because it might contain other contaminants above safe levels for which nosediment criteria exist. Inaddition, the synergistic, antagonistic, or additive effects of

(8!15!94) 3-29WaterQuality StandardsHandhwk -SecondE&bon

several contaminants in the sediments may beof
concern.

Additional testing in other tiers of an evaluation approach, suchastoxicity tests, could berequired todetermine if the sediment is safe. It is likely that such testing would incorporate site-specific considerations. Examples ofspecific applications of sediment criteria after they are developed include the following:

0 Establish permit limits for point sources to
ensure that uncontaminated sediments remain uncontaminated or sediments already contaminated have anopportunity tocleanse themselves. Of course, this would occur only after criteria and the meanstotie point
sources to sediment contamination are developed.

l Establish target levels for nonpoint sources of sediment contamination.

0 For remediation activities, SQC would be valuable in identifying:

- need for remediation.

- spatial extent of remediation area,

- benetits derived from remediation activities,

- responsible parties, - impacts of depositing contaminated sediments in water environments, and

- successof remediation activities.

In tiered testing sediment evaluation processes, sediment criteria andbiological testing procedures work very well together.



### Sediment Criteria Status

ScienceAdvisory Board Review

The Science Advisory Board has completed a second review of the EqP approach to deriving sediment quality criteria for non-ionic contaminants. The November 1992 report (USEPA, 1992~) endorses the EqP approach to deriving criteria as ‘I.

. .sufficiently valid to be used in the regulatory process if the uncertainty associated with the method is considered, described, and incorporated,” and that “EPA should

. . . establish criteria on the basis of present knowledge within the bounds of uncertainty.

. . .”

The Science Advisory Board also identified the need for “.

. . a better understanding of the uncertainty around theassumptions inherent inthe approach, including assumptions of equilibrium, bioavailability, and kinetics, all critical to the application of the EqP.”



### Sediment Criteria Documents and Application Guidance

EPA efforts at producing sediment criteria documents are being directed first toward phenanthrene, fluoranthene. dieldrin, acenaphthene, andendrin. Efforts arealso being directed towards producing aguidance docurncnt
on the derivation and interpretation of sediment quality criteria. The criteria documents were announced in the 

### Fe&ml ReKisrer in January 1994; the public comment period ended June 1994. Final documents and implementation guidance should beavailable in early 1996.

### Methodology for Developing Sediment

Criteria for Metal Contaminants

EPA isproceeding todevelop amethodology for calculating sediment criteria for benthic toxicity to metal contaminants, with key work focused on identifying and understanding the role of acid volatile sulfides (AVS), andother binding factors, in controlling the bioavailability of metal contaminants. A variety of field and laboratory verification studies are under way 10 add additional support tothe methodology. Standard AVS sampling and analytical procedures are under development. Presentation of the metals methodology totheSAB for review isanticipated for Fall 1994.


### BiolbgicaL Approach to Sediment Criteria Development

Under the Contaminated Sediment Management Strategy, EPA programs havecommitted tousing consistent biological methods to determine if sediments are contaminated. In the water program, thesebiological methods will beusedas a complement to the sediment-chemical criteria under development. The biological methods consist ofboth toxicity andbioaccumulation tests. Freshwater andsaltwater benthic species, selected to represent the sensitive range of species’ responses totoxicity. are used in toxicity teststo
measure sediment toxicity. Insensitive freshwater andsaltwater benthic speciesthatform thebaseof the food chain are used in toxicity tests to
measure the bioaccumulation potential of sediment. In FY 1994, acute toxicity tests and bioaccumulation tests selected by all the Agency programs should bestandardized andavailable for
use. Training for States and EPA Regions on these methods isexpected to begin in FY1995.

In the next few years, research will beconducted to develop standardized chronic toxicity testsfor sediment as well as toxicity identification evaluation (TIE) methods. TheTIE approach will be used to identify the specific chemicals in a sediment causing acute or chronic toxicity in the 

### test organisms. Under the Contaminated Sediment Management Strategy, EPA’s programs have also agreed to incorporate these chronic toxicity and TIE methods into their scdirncnt testing when they are available.



### 3.5.5 Wildlife Criteria

Terrestrial and avian spccics arc usciul as sentinels for the health of the ecob>‘stcnl as a whole. In many cases, damage to wildlife indicates that the ecosystem Itself is damaged. Many wildlife species that are heavily dependent
on the aquatic food web reflect the health of aquatic systems. In the caseof toxic chemicals, terminal predators such as otter, mink. gulls, terns, eagles, ospreys, and turtles arc useful as integrative indicators of thestatusor health ofthe ecosystem, 

### Statutory and Regulatory Authoritl

Section 101(a)(2) of theCWA sets.asan interim goal of,

. . . wherever attainable

. . water quality which provides for the



### SK:tion 304(a)( I)oftheAct also rcquircs ItPA to: protectio n shellfish, added). and propagation of fish.

and wildlife

. (emphasis

. . . develop and publish criteria for water quality accurately reflecting

. . . the kind and extent of all identifiable effects on health and welfare including

. . .wildlife.

The Water Quality Standards Regulation reflect the statutory goals and requirements by requiring States to adopt, where attainable, the CWA section 101(a)(2) goal uses of protection and propagation of fish, shellfish, and n,ildlife (40 CFR 131.lo), and toadopt water quality criteria sufficient to protect the designated USL’(40 CFR 131.11).

(8/15/94) 3-31WaterQuality Se Handbook -SecondEdition



### Wildlife Protection in Current Aquatic Criteria

Current water quality criteria methodology is designed toprotect fish, benthic invertebrates, and zooplankton; however, there isaprovision in the current aquatic life criteria guidelines (Appendix H) that is intended to protect wildlife that
consume aquatic organisms from the bioaccumulative potential of a compound. The final residue value can be based on either the FDA Action Level or a wildlife feeding study. However, if maximum permissible tissue concentration is not available from a wildlife feeding study, a final residue value cannot be derived and the criteria quantification procedure continues without further consideration ofwildlife impacts. Historically, wildlife have been considered only after detrimental effects on wildlife populations have been observed in the environment (this occurred with relationship to DDT, selenium, and PCBs).



### Wildlife Criteria Development

EPA’s national wildlife criteria effort began following release of a 1987 Government Accounting Office study entitled 

### Wild@? Munagement -Nutionul RefugeContamination Is D$iculr ToConfirm andCleun Up(GAO, 1987). After waterfowl deformities observed atKesterson Wildlife Refuge were linked to selenium contamination in the water, Congress requested this study and recommended that “the Administrator of EPA, inclose coordination with the Secretary of the Interior, develop water quality criteria for protecting wildlife and their refuge habitat. q
In November of 1988, EPA’s Environmental Research Laboratory in Corvallis sponsored a workshop entitled Wurer 

### Quality Criteria To Protect Wildli/4 Resources, (USEPA, 1989g) which was co-chaired by EPA and the Fish and Wildlife Service (FWS). The workshop brought together 26 professionals from a variety of institutions, including EPA, FWS, State governments, academia, andconsultants who had expertise in wildlife toxicity, aquatic toxicity, =)logy 7 environmental risk assessment, and conservation. Efforts atheworkshop focused on evaluating theneedfor, anddeveloping astrategy for production of wildlife criteria. Two recommendations came out of that workshop:
(1) The process by which ambient water quality criteria are established should be modified to consider effects on wildlife; and
(2) chemicals should be prioritized based on their potential to adversely impact wildlife species.

Based on the workshop recommendations, screening level wildlife criteria (SLWC) were calculated for priority pollutants andchemicals of
concern submitted bytheFWS togauge theextent of the problem by:
(1) evaluating whether existing water quality criteria for aquatic life are protective of wildlife, and
(2) prioritizing chemicals fortheir potential toadversely impact wildlife species.

There were 82chemicals for which EPA had the necessary toxicity information aswell asambient water quality criteria, advisories, or lowestobserved-adverse-effect levels (LOAELs) to compare with the SLWC values. As would be expected, the majority of chemicals had SLWC larger than existing water quality criteria, advisories, or LOAELs for aquatic life. However, the screen identified classes of compounds for which current ambient water quality criteria may not beadequately protective of wildlife: chlorinated alkanes, benzenes, phenols, metals, DDT, and dioxins. hlany of these compounds are produced in very large amounts and have a variety of uses (e.g., solvents, flame retardants, organic syntheses of fungicides and herbicides, and manufacture of plastics andtextiles. The manufacture and useof

3-32 (8:lSi94)ChaDler3-WaterC?udiN Critm’a

these materials produce waste byproduct). Also, 5 of the 21 are among the top 25 pollutants identified atSuperfund sites in 1985 (3 metals, 2 organ&).
Following this initial effort, EPA held anational meeting in April 1992’ to constructively discuss andevaluate proposed methodologies for deriving wildlife criteria to build consensus among the scientific community as to the most defensible scientifically approach(es) tobe pursued by EPA indeveloping useful andeffective wildlife criteria.

The conclusions of this national meeting were as follows:

0 wildlife criteria should have atissue-residue component when appropriate;

0 peer-review of wildlife criteria anddatasets should be used in their derivation;

a wildlife criteria should incorporate methods toestablish site-specific wildlife criteria;

0 additional amphibian andreptile toxicity data
are needed;

l further development of inter-species toxicological sensitivity factors are needed; and 0 criteria methods should measure biomarkers in conjunction with other studies.

On April 16, 1993, EPA proposed wildlife criteria in the 

### Wurer Qualify Guidunce for fk Great Lakes Sysrem (58 F.R. 20802). The proposed wildlife criteria arebasedonthecurrent EPA noncancer human health criteria approach. In this proposal, in addition to requesting comments on the proposed Great Lakes criteria and methods, EPA also requested comments on possible modifications of the proposed Great Lakes approach for consideration in the development of national wildlife criteria.



### 3.5.6 Numeric Criteria for Wetlands

Extension of the EPA national 304(a) numeric aquatic life criteria to wetlands is recommended
as part of a program to develop standards and criteria for wetlands. Appendices D and E provide anoverview oftheneed for standards and criteria for wetlands. The 304(a) numeric aquatic life criteria are designed to be protective of aquatic life for surface waters and are generally applicable to most wetland types. Appendix E provides apossible approach, based on the sitespecific guidelines, for detecting wetland types that might not beprotected by direct application of national 304(a) criteria. The evaluation canbe simple and inexpensive for those wetland types for which sufficient water chemistry and species assemblage data are available, but will be less useful for wetland types for which these dataare not readily available. In Appendix E, the sitespecific approach isdescribed and recommended for wetlands for which modification of the304(a) numeric criteria are considered necessary. The results of this type of evaluation, combined with information on local or regional environmental threats, can be used to prioritize wetland types (and individual criteria) for further site-specific evaluations and/or additional data collection. Close coordination among regulatory agencies, wetland scientists, and criteria experts will be required.

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### 3-33Water Quality StadarJs tiandtxx)k -SecondEdition 

# cl 3.6 Policy on Aquatic Life Criteria for Metals

It isthe policy of theOffice ofWater that theuse of dissolved metal tosetand measure compliance with water quality standards isthe recommended approach, because dissolved metal more closely approximates thebioavailable fraction of metal in the water column than does total recoverable metal. This conclusion regarding metals bioavailability is supported by a majority of the scientific community within and outside EPA. One reason isthataprimary mechanism forwater column toxicity is adsorption at the gill surface which requires metals tobeinthedissolved form.

Until the scientific uncertainties are better resolved, a range of different risk management decisions can be justified by a State. EPA recommends that State water quality standards be based on dissolved metal--a conversion factor must beused inorder toexpress the EPA criteria articulated astotal recoverable asdissolved. (See the paragraph below for technical details on developing dissolved criteria.) EPA will also approve aStaterisk management decision toadopt standards based on total recoverable metal, if those standards are otherwise approvable as a matter of law. (o$?ce (f Wurer Polity 

### and Technicui Guidunc*e 

### on Inteprerarion and Implemenrurion of Aquatic Lif4 Meruls Cri(eria USEPA, 1993f)



### 3.6.1 Background

The implementation of metals criteria iscomplex due tothe site-specific nature of metals toxicity. This issuecovers anumber of areasincluding the expression of aquatic life criteria; total maximum daily loads (TMDLs), permits, effluent monitoring, and compliance; and ambient monitoring. The following Sections, basedonthe policy memorandum referenced above, provide additional guidance in each 

### of these areas. Included in this Handbook as Appendix J are three guidance documents issued along with the Office of Water policy memorandum with additional technical &tails. They arc: (;rtitiurrcv 

### Docwrrenr onElrpw.\.vionof.4cprrc‘ 

### l,if> C‘rilcjriu
usI>issrh~edC’rircrid (.Atta~~hmcrlt

### #Z), (;rridutrc.u Uocumenronll~numic*Midc*lin,qtlrui Trtrn.~Ifrror.s (Attachment #3). and (;uitfto~t~ I)oc~14m4~ru on 

### Monitoring (Attachment #4). These will be supplement& asadditional inti~rmation bcconles available.

Since metals toxicity is significantly affected by site-specific factors, it presents a number of programmatic challenges. Factors that must be considered in the rnanagcment of metals in the aquatic environment include: toxicity specitic to effluent chemistry; toxicity specific to ambient water chemistry; different ptttcrns of toxicity for different metals; evolution 

## oithestate ofthe science of metals toxicity. fate. ilnd transport;
resource limitations for monitoring. analysis, implementation. and research functions; concerns regarding someoftheanalytical datacurrently on record due to possible sampling and analytical contamination; and lack of standardized protocols for clean and ultraclcan m&Is analysis. The States have the key role in the risk management process of balancing these factors in the management ofwater programs. The site-specific nature of this issue could he perceived as requiring a permit-hy-permit approach to implementation. Howc\.t’r. IFA belic\,es thatthis guidance can be cffcctively implemented on a broader level, across any w’ntcrs with roughly the
same physical and chcrnrcal characteristics, and recommends that Stateswork with the III’,4 with that perspctive in mind.



### 3.6.2 Expression ofAquatic Life Criteria

Dissolved vs. Total Hecovemhle .\letal

A major issue is whether, and how, to use dissolved metalconcentrations (“dissolved metal”)
or total recoverable metal concentrations (“total recoverable metal”) III setting State water quality standards. In the past, States t1aL.cused both approaches when applying thesame EPA Section 304(a) criteria guidance. Some older criteria documents may have facilitated thcsc diifcrentChapter 3-WaterQuality Cri~ria

approaches tointerpretation ofthecriteria because the documents were somewhat equivocal with regards to analytical methods. The May 1992 interim guidance continued the policy that either approach was acceptable.

The position that thedissolved metals approach is
more accurate has been questioned because it neglects thepossible toxicity of particulate metal. It is true that some studies have indicated that particulate metals appear to contribute to the toxicity of metals, perhaps becauseoffactors such
as desorption of metals at the gill surface, but these same studies indicate the toxicity of particulate metal is substantially lessthan that of dissolved metal.

Furthermore, any error incurred from excluding thecontribution ofparticulate metalwill generally becompensated by other factors which make criteria conservative. For example, metals in toxicity tests are added as simple salts to relatively clean water. Due tothelikely presence of a significant concentration of metals binding agents in many discharges and ambient waters, metals in toxicity tests would generally be expected to be more bioavailable than metals in discharges or in ambient waters.

If total recoverable metal is used for the purpose of specifying water quality standards, the lower bioavailability of particulate metal and lower bioavailability of sorbed metals asthey are discharged may result in an overly conservative water quality standard. The use of dissolved metal in water quality standards gives a more accurate result in the water column. However, total recoverable measurements in ambient water have value, in that exceedences of criteria on a total recoverable basisareanindication that metal loadings could be a stress to the ecosystem, particularly in locations other than the water column (e.g., in the sediments).

The reasons for thepotential consideration oftotal recoverable measurements include risk management considerations not covered by evaluation of water column toxicity alone. The ambient water quality criteria areneither designed
nor intended to protect sediments, or to prevent effects in the food webs containing sediment dwelling organisms. A risk manager, however, may consider sediments and food chain effects and may decide to take aconservative approach for metals, considering that metals are very persistent chemicals. This conservative approach could include the useoftotal recoverable metal in water quality standards. However, since consideration of sediment impacts is not incorporated into the criteria methodology, the degree of conservatism inherent in the total recoverable approach is unknown. The uncertainty of metal impacts in sediments stem from the lack of sediment criteria and an imprecise understanding of the fate and transport of metals. EPA will continue to pursue research andother activities toclose theseknowledge gaps.

Dissolved Cfiteriu

In the toxicity tests used to develop EPA metals criteria for aquatic life, somefraction ofthemetal is dissolved while some fraction is bound to particulate matter. The present criteria were developed using total recoverable metal measurements or measures expected to give equivalent results in toxicity tests, and are articulated as total recoverable. Therefore, in order toexpress the EPA criteria asdissolved, a total recoverable to dissolved conversion factor must be used. Attachment #2 in Appendix J provides guidance for calculating EPA dissolved criteria from the published total recoverable criteria. The data expressed aspercentage metal dissolved are presented as recommended values andranges. However, thechoice within ranges is
a State risk management decision. EPA has recently supplemented the data for copper and is proceeding to further supplement the data for copper andother metals. Astesting iscompleted, EPA will makethis information available andthis isexpected toreduce the magnitude of the ranges for some of the conversion factors provided. EPA also strongly encourages the application of dissolved criteria across a watershed or

(8115194) 3-35W8terQuality Straduds Handback -SecondEditiom

water-body, astechnically sound and the best use of resources.
Site-Specfic Criteria ModQhtions

While the above methods will correct some sitespecific factors affecting metals toxicity, further refinements are possible. EPA has issued guidance for three site-specific criteria development methodologies: recalculation procedure, water-effect ratio (WER) procedure (called theindicator species procedure inprevious guidance) and resident species procedure. (See Section 3.7 of this Chapter.)

In the National Toxics Rule (57 FR 

### 60848, December 22, 1992), EPA recommended the WER as an optional method for site-specific criteria development for certain metals. EPA committed in the NTR preamble to provide additional guidance on determining the WERs. 

### The Interim Guidance onrheDetermination and UseofWater-Eflect Rutiosfor MetaLrwas issued by EPA on February 22, 1994and isintended to fulfill that commitment. This interim guidance supersedes all guidance concerning water-effect ratios and the recalculation procedure previously issued by EPA. This guidance is included as Appendix L tothis Handbook.

In order to meet current needs, but allow for changes suggested by protocol users, EPA issued the guidance as “interim.” EPA will accept WERs developed using this guidance, aswell as by using other scientifically defensible protocols. 

### 3.6.3 Total Maximum Daily Loads (TMDLs) and National Pollutant Discharge Elimination System (NPDES) Permits

Dynamic Water Quaiity Modeling
Although not specifically part ofthe reassessment of water quality criteria for metals, dynamic 

### or probabilistic models are another useful tool for implementing water quality criteria, especially for those criteria protecting aquatic life. These models provide another way to incorporate sitespecific data. The 

### Technical Suppn Document for Water Quulity-bused Toxics Conrrol (TSD) (USEPA, 1991a) describes dynamic, as well as static (steady-sbte) models. Dynamic models make the best use of the specified magnitude, duration, and frequency of water quality criteria and, therefore, provide a more accurate representation of the probability that a water quality standard exceedence will occur. In contrast, steady-state models frequently apply a number of simplifying, worst case assumptions which makes them less complex but also less accurate than dynamic models.
Dynamic models havereceived increased attention
over the last few years as a result of the widespread belief that steady-state modeling is over-conservative due to environmentally conservative dilution assumptions. This belief has ledtothemisconception thatdynamic models will always lead to less stringent regulatory controls (e.g., NPDES effluent limits) than steady-state models, which is not true in every application of dynamic models. EPA considers dynamic models to beamore accurate approach to implementing water quality criteria andcontinues torecommend their use. Dynamic modeling does require a commitment of resources to develop appropriate data. (See Appendix J, Attachment #3 and the USEPA, 1991afor details on tht: useof dynamic models.)

Dissolved-Total Metal Tmnsltlrors
Expressing ambient water quality criteria for metals asthe dissolved form of a metal poses a



### 3-36 (8’15’94)Chaprer 3-Warrr Quality Crirrria

need to beable to translate from dissolved metal to total recoverable metal for TMDLs and NPDES permits. TMDLs for metals mustbeable to calculate: (1) dissolved metal in order to ascertain attainment of water quality standards, and (2)total recoverable metal inorder toachieve
massbalance necessary for permitting purposes.

EPA’s NPDES regulations require that limits of metals in permits bestatedastotal recoverable in most cases(see40CFR #122.45(c)) except when
an effluent guideline specifies the limitation in another form ofthe metal, theapproved analytical methods measure only dissolved metal, or the permit writer expresses ametals limit in another form (e.g., dissolved, valent specific, or total) when required to carry out provisions of the Clean Water Act. This is because the chemical conditions in ambient waters frequently differ substantially from those in the effluent, andthere is no assurance that effluent particulate metal would not dissolve after discharge. The NPDES rule does not require that State water quality standards be expressed as total recoverable; rather, therule requires permit writers totranslate between different metal forms inthecalculation of the permit limit sothat atotal recoverable limit
canbeestablished. Roth theTMDL and NPDES
usesof water quality criteria require theability to translate between dissolved metal and total recoverable metal. Appendix J, Attachment #3 provides guidance on this translation.



### 3.6.4 Guidance on Monitoring

Use of Clean Sampling and Analytical Techniques

Inassessing waterbodies todetermine thepotential for toxicity problems duetometals, thequality of the data used isan important issue. Metals data
are used todetermine attainment status for water quality standards, discern trends in water quality, estimate background loads for TMDLs, calibrate fate and transport models, estimate effluent concentrations (including effluent variability),
assesspermit compliance, and conduct research. The quality of trace level metal data, especially below 1 ppb, may be compromised due to contamination of samples during collection, preparation, storage, andanalysis. Depending on the level of metal present, the useof “clean” and “ultraclean” techniques for sampling andanalysis may be critical to accurate data for implementation of aquatic life criteria for metals.

The significance of the sampling and analysis contamination problem increases asthe ambient and effluent metal concentration decreases and, therefore, problems are more likely in ambient measurements. “Clean” techniques refer tothose requirements (or practices for sample collection and handling) necessary to product reliable analytical data inthe part per billion (ppb) range. “Ultraclean” techniques refer to those requirements or practices necessary to produce reliable analytical data inthepart pertrillion (ppt) range. Because typical concentrations of metals in surface waters and effluents vary from one metal to another, the effect of contamination on the quality of metals monitoring data varies appreciably.

EPA plans to develop protocols on the use of clean and ultra-clean techniques and is coordinating with the United States Geological Survey (USGS) onthis project, bccausc USGS has been doing work on these techniques for some time, especially thesampling proccdurcs. Draft protocols for clean tcchniqucs were presented at theNorfolk, VA analytical methods confcrcnce in the Spring of 1994 and final protocols are expected to be available in early 1995. The development of comparable protocols for ultraclean techniques isunderway and are expected to be available in late 1995. In dr\,cloping these protocols, we will consider the costs of these techniques and will give guidance as to the situations where their useisnecessary. Appendix L, pp. 98-108 provide some general guidance on the use of clean analytical tcchniqucs. We recommend that this guidance hc used by States and Regions asan interim step, while the clean and ultra-clean protocols are hcing dcicloped.

(8!15/94) 3-37WaterOualrtv StandardsHandbook -SecondEd&m

Useof ~listoricd l&a

The concerns about metals sampling andanalysis discussed above raise corresponding concerns about the validity of historical data. Data on effluent and ambient metal concentrations are collected by avariety of organizations including Federal agencies (e.g., EPA, USGS), State pollution control agencies andhealth departments, local govern ment agencies, municipalities, industrial dischargers, researchers, and others. The dataarecollected for avariety of purposes as discussed above.

Concern about the reliability of the sample collection and analysis procedures is greatest where they have been used to monitor very low level metal concentrations. Specifically, studies haveshown datasetswith contamination problems during sample collection and laboratory analysis, that have resulted in inaccurate measurements. For example, in developing a TMDL for New York Harbor. some historical ambient data showed extcnslve metals problems in the harbor, while other historical ambient data showed only limited metaIs problems. Careful resampling and analysis In 19921993 showed the Iatter view was correct. The key to producing accurate data is appropriate quality assurance (QA) and quality control (CJ‘) procedures. EPA believes that most historical data for metals, collected and analyzed with appropriate QA andQC atlevels of 1ppbor higher, are reliable. The data used in development of EPA criteria are also considered reliable, both because they meet the above test and because thetoxicity testsolutions arecreated byadding known amounts of metals.

With respect toeffluent monitoring reported byan NPDES permittee, thepermittee isresponsible for collecting and reporting quality data on a Discharge Monitoring Report (DMR). Permitting authorities should continue to consider the information reported to be true, accurate, and complete ascertified bythepermittee. Where the permittee becomes aware of new information specific totheeffluent discharge thatquestions the quality of previously submitted DMR data, the permittee must promptly submit that information to the permitting authority. The permitting authority will consider all information submitted by the permittee in determining appropriate enforcement responses to monitoring/reporting and effluent violations. (See Appendix J, Attachment #4for additional details.)

cl 

### 3.7 Site-Specific Aquatic Life Criteria

The purpose ofthis section istoprovide guidance for thedevelopment of site-specific water quality criteria which reflect local environmental conditions. Site-specific criteria are allowed by regulation and are subject to EPA review and approval. The Federal water quality standards regulation at section 

### 131.1l(b)( l)(ii) provides Stateswith theopportunity toadopt water quality criteria thatare*

...modified toreflect site-specific conditions. * Site-specific criteria, as with all water quality criteria, must bebased on asound scientific rationale in order to protect the designated use. Existing guidance and practice
are that EPA will approve site-specific criteria developed using appropriate procedures.

Asite-specific criterion isintended tocome closer than the national criterion to providing the intended level of protection to the aquatic life at the site, usually by taking into account the biological and/or chemical conditions (i.e., the species composition and/or water quality characteristics) atthesite. The fact that the U.S. EPA hasmadethese procedures available should not be interpreted as implying that the agency advocates that states derive site-specific criteria before setting statestandards. Also, derivation of
a site-specific criterion does not change the intended level of protection of the aquatic life at thesite.



### 3.7.1 History of Site-Specific Criteria Guidance

National water quality criteria for aquatic life may beunder- or over-protective if:

3-38 (8115194)Chapter 3-WaterQud+ Cruu-itI

(1) the species at the site are more or less sensitive than those included in the national criteria data set (e.g., the national criteria data set contains data for trout, salmon, penaeid shrimp, and other aquatic species that have been shown to be especially sensitive to some materials), or
(2) physical and/or chemical characteristics of the site alter the biological availability and/or toxicity of the chemical (e.g., alkalinity, hardness, pH, suspended solids and salinity influence theconcentration(s) of the toxic form(s) of some heavy metals, ammonia and other chemicals).

Therefore, it is appropriate that site-specific procedures address each of these conditions separately aswell asthecombination of thetwo. In the early 1980’s, EPA recognized that laboratory-derived water quality criteria might not accurately reflect site-specific conditions and, in response, created three procedures toderive sitespecific criteria. This Handbook contains the details of these procedures, referenced below.

1. The Recalculation Procedure is intended to take into account relevant differences between the sensitivities of the aquatic organisms in the national dataset and the sensitivities of organisms that occur at the site (seeAppendix L, pp. 90-97).



### 2. The Water-Effect Ratio Procu (called the Indicator Species Procedure in USEPA, 1983a; 1984f ) provided for the use of a water-effect ratio (WER) that is intended to take into account relevant differences between the toxicities of the chemical in laboratory dilution water and in site water (seeAppendix L).



### 3. The Resident ws Procedm intended to take into account both kinds of differences simultaneously (seeSection 3.7.6).

These procedures were first published inthe 1983 

### Water Quality Stundurds Handbook (USEPA, 1983a) and expanded upon in the Guidelinasfor 

### Deriving Numerical Aquaric Site-SpeciJic Watt>r Quuiity Criteriu by Mtdfiing hlurionul Critcriu (USEPA, 1984f). Interest hasincreased in recent years as states have devoted more attention to chemical-specific water quality criteria foraquatic life. In addition, interest in water-effect ratios increased when they were integrated into someof the aquatic life criteria for metals that were promulgated for several states in the National Toxics Rule (57 E.B60848. December 22, 1992). The 

### Oflee of Water Policy and Technicul GuidanceonIntegwetarion andImplementation of Aquutic Lif4 Criteria for Metals (USEPA, 19930 (see Section 3.6 of this Handbook) provided further guidance onsite-specific criteria for metals by recommending the useof dissolved metals for setting and measuring compliance with water quality standards.

The early guidance concerning WERs (USEPA, 1983a; 1984f) contained few details and needed revision, especially to take into account newer guidance concerning metals. To meet this need, EPA issued 

### Interim Guidunc-e on the Determination and UseofWater-Eflec.1Rutiosfor Metals in 1994 (Appendix L). Metals are specifically addressed in Appendix L because of the National Toxics Rule and because of current interest inaquatic life criteria for metals; although most of this guidance also applies to other pollutants, someobviously applies only tometals. Appendix L supersedes a!1guidance concerning water-effect ratios and the Indicator Species Procedure given in Chapter 4 of the 

### Wuter Quality Stand&s Handbook (USEPA, l983a) and in

### Guidelinesfor Deriving h?unericul Aquutic SiteSpecljic Water Quuiity Criteriu by Mod@ing Nutional Criteria (USEPA, 1984f). Appendix I- (p. 90-98) also supersedes the guidance in these earlier documents for the Recalculation Procedure forperforming site-specific criteria modifications. The Resident Species Procedure remains essentially unchanged since 1983 (except for changes in the averaging priods to conform to the 1985aquatic life criteria guidelines (USEPA. 198Sb) and ispresented in Section 3.7.6, below.

(8f15f94) 

### 3-39Water Oual~tv Stan&r& Handbook -Second Edition

The previous guidance concerning site-specific procedures did nor allow the Recalculation Procedure and the WER procedure to be used together inthederivation ofasite-specific aquatic life criterion; the only way to take into account both species composition and water quality characteristics in the determination of a sitespecific criterion was to usethe Resident Species Procedure. Acidic change contained Atgendk

w excut in iurisdictions thataresm the National Toxics Rule. the Recalculation Procedure and the WER Procedure may 

### now be

ther provided that the recalculation procedure is performed first. Both the Recalculation Procedure and theWER Procedure
are based directly on the guidelines for deriving national aquatic life criteria (USEPA 1985 )and, when the two are used together, use of the Recalculation Procedure must be performed first because the Recalculation Procedure hasspecific implications concerning the determination of the WER.



### 3.7.2 Preparing to Calculate Site-Specific 

### Criteria
Adopting site-specific criteria in water quality standards is a State option--not a requirement. Moreover, EPA is not advocating that States use site-specific criteria development procedures for setting all aquatic life criteria asopposed tousing the National Section 304(a) criteria recommendations. Site-specific criteria are not needed in all situations. When aStateconsiders thepossibility of developing site-specific criteria, it is essential to involve the appropriate EPA Regional office atthe start of the project.

This early planning isalso essential if it appears thatdatageneration andtesting may beconducted byaparty other than theStateor EPA. The State and EPA needtoapply theprocedures judiciously and must consider thecomplexity of theproblem andtheextent of knowledge available concerning the fate and effect of the pollutant under consideration. If site-specific criteria are developed without early EPA involvement in the planning and design of the task. the State may expect EPA to take additional time to closely scrutinize theresults before granting anyapproval totheformally adopted standards.

The following sequence of decisions need to be made before any of the procedures are initiated:

+ verify that site-specific criteria are actually needed (e.g., that the useof clean sampling and/or analytical techniques, especially for metals, do not result in attainment of standards.)

+ Define thesite boundaries.

+ Determine from the national criterion document and other sources if physical and/or chemical characteristics areknown to affect the biological availability and/or toxicity of amaterial of interest.

+ If data in the national criterion document and/or from other sources indicate that the range of sensitivity of the selected resident speciestothematerial of interest isdifferent from therange for thespecies inthenational criterion document, andvariation inphysical and/or chemical characteristics of the site water isnot expected to beafactor, usethe 

### Reculmlurion Prowdure (Section 3.7.4).

3-40 (8!15!94)Chuplcr 3-Wtrwr Qdiry Critrria

+ If data in the national criterion document and/or from other sources indicate that physical and/or chemical characteristics of the site water may affect the biological availability and/or toxicity of thematerial of interest, and the selected resident species range of sensitivity issimilar tothat for the species in the national criterion document,


### use the 

### Wuter-E$Pct Ratio Procedure (Section 3.7-S).

+ If data in the national criterion document and/or from other sources indicated that physical and/or chemical characteristics of the site water may affect the biological availability and/or toxicity of thematerial 

### of interest, and the selected resident species range of sensitivity isdifferent from that for the species in the national criterion document, and if both these differences are to be taken into account, use the 

### Reculculwion Procedure inconjunction with the Wuter-E$ect Rutio Procedure or usethe 

### Resident SpeciesProcedure (Section 3.7.6).



### 3.7.3 Definition ofaSite

Since the rationales for site-specific criteria are usually based on potential differences in species sensitivity, physical and chemical characteristics of the water, or acombination of the two, the concept of site must be consistent with this rationale.

In the general context of site-specific criteria, a “site” may be a state, region, watershed, water-body, or segment ofawaterbody. The sitespecific criterion is to be derived to provide adequate protection for the entire site, however the site isdefined.

If water quality effects on toxicity are not a consideration, the site can be 

### as large as a generally consistent biogeographic zone permits. For example, large portions of the Chesapeake Bay, Lake Michigan, or the Ohio River may be considered asone site if their respective aquatic communities donotvary substantially. However, when asite-specific criterion isderived using the Recalculation Procedure, all species that “occur at the site” need to be taken into account when deciding what species, if any, are to be deleted from the dataset. Unique populations or less sensitive uses within sites may justify a designation asadistinct site.

If the species of a site are toxicologically comparable to those in the national criteria data setfor amaterial of interest, and physical and/or chemical water characteristics aretheonly factors supporting modification of the national criteria, then the site can be defined on the basis of expected changes in the material’s biological availability and/or toxicity due to physical and chemical variability of the site water. However, when asite-specific criterion is derived using a WER, theWER isto beadequately protective of the entire site. If, for example. a site-specific criterion is being derived for an estuary, WERs could bedetermined using samples of thesurface water obtained from various sampling stations, which, to avoid confusion, should not be called “sites”. Ifall theWERs were sufficiently similar,
one site-specific criterion could be derived to apply to the whole estuary. If tht: WERs were sufficiently different, either thelowest WE,Rcould be usedto derive asite-specific criterion for the whole estuary, or thedata might indicate that the estuary should bedivided into two or more sites, eachwith its own criterion.



### 3.7.4 The Recalculation Procedure

The Recalculation Procedure is intended tocause a site-specific criterion to appropriately differ from anational aquatic life criterion ifjustified by demonstrated pertinent toxicological differences between the aquatic species that occur atthe site and those that were used in the derivation of the national criterion. There areatleastthree reasons why suchdifferences might exist between thetwo setsof species.

+ First, the national dataset contains aquatic species thataresensitive to many pollutants,Water &al~ty Standards Handbook -Second Edltlon

but these and comparably sensitive species might not occur atthe site.

+ Second, aspecies that is critical atthe site might be sensitive to the pollutant and require alower criterion. (A critical species is a species that is commercially or recreationally important atthesite, aspecies that exists at the site and is listed as threatened or endangered under section 4of the Endangered SpeciesAct, oraspeciesfor which there isevidence that the loss of the species from the site is likely to cause an unacceptable impact on a commercially or recreationally important species, athreatened
or endangered species, the abundances of a variety of other species, or the structure or function of the community.)

+ Third, the species that occur at the site might represent a narrower mix of species than those in the national dataset due to a limited range of natural environmental conditions.

The procedure presented in Appendix L, pp. 90- 98 isstructured sothat corrections and additions
can be made to the national dataset without the deletion process being used to take into account taxa that do not occur at the site; in effect, this procedure makes it possible toupdate thenational aquatic life criterion. All corrections and additions that have been approved by EPA are required, whereas useof the deletion process is optional. The deletion process may not be used to remove species from the criterion calculation that are not currently present at a site due to degraded conditions.

The Recalculation Procedure is more likely to result in lowering acriterion if the net result of addition anddeletion istodecrease thenumber of genera in the dataset. whereas the procedure is
more likely to result in raising acriterion if the net result of addition and deletion is to increase the number of genera in the dataset.

For the lipid soluble chemicals whose national Final Residue Values arebasedon Food and Drug Administration (FDA) action levels, adjustments inthose values basedon the percent lipid content of resident aquatic species is appropriate for the derivation of site-specific Final Residue Values. For lipid-soluble materials, the national Final Residue Value isbasedon anaverage I1percent lipid content for edible portions for thefreshwater chinook salmon and lake trout and anaverage of 10 percent lipids for the edible portion for saltwater Atlantic herring. Resident species of
concern may have higher (e.g., Lake Superior siscowet, a race of lake trout) or lower (e.g., many sport fish) percent lipid content than used for thenational Final Residue Value.Chapter 3-Wufrr QucdirvCriwrkr

For some lipid-soluble materials such as polychlorinated biphenyls (PCB) and DDT, the national Final Residue Value isbasedon wildlife
consumers of fish andaquatic invertebrate species rather than an FDA action level because the former provides a more stringent residue level. Seethe National Guidelines (USEPA, 1985b) for details.

For the lipid-soluble materials whose national Final Residue Values are based on wildlife effects, the limiting wildlife species (mink for PCB and brown pelican for DDT) areconsidered acceptable surrogates for resident avian and mammalian species (e.g., herons, gulls, terns, otter, etc.) Conservatism isappropriate for those two chemicals, andnolessrestrictive modification ofthenational Final Residue Value isappropriate. The site-specific Final Residue Value would be the sameasthe national value.

3.7.5 

### The Water-Effect Ratio (WER) Procedure

The guidance ontheWater-Effect Ratio Procedure presented in Appendix L is intended to produce WERs that may be used to derive site-specific aquatic life criteria from most national and state aquatic life criteria that were derived from laboratory toxicity data.

As indicated in Appendix L, the determination of awater-effect ratio may require substantial resources. A discharger should consider cost-effective, preliminary measures described in this Appendix L (e.g., useof “clean” sampling and chemical analytical techniques especially for metals, or in non-NTR States, a recalculated criterion) todetermine ifanindicator species site-specific criterion isreally needed. In many instances, useof theseother meaSuresmay eliminate theneedfor deriving water-effect ratios. The methods described in the 1994 interim guidance (Appendix L) should be sufficient to develop site-specific criteria that resolve concerns of dischargers when there appears to be no instream toxicity but, where (a) a discharge appears to exceed existing or proposed water quality-based permit limits, or (b) an instream concentration appears to exceed an cxlsting or proposed water quality criterion.

WERs obtained usinp the methods described in &pendix L should onlv beusedtoadjust aauatic

. . life mena that were derived usinp laboratory toxicitv WERs determined using the methods described herein cannot beusedtoadjust the residue-based mercury Criterion Continuous Concentration (CCC) or the field-based selenium freshwater criterion.
Except in jurisdictions that are subject to the NTR, the WERs may also be used with sitespecific aquatic life criteria that arederived using the Recalculation Procedure described in Appendix L (p.90).

Water-wfect Ratios in the Detivafion of Site-Specfic C.lireti.0

A central question concerning WIlRs is whether their use by a State results in a sitc-specific criterion subject to EPA review and approval under Section 303(c) of the Clean Water Act?

Derivation of awater-effect ratio by aState isa site-specific criterion adjustment subject to EPA review and approval/disapproval under Section 303(c). There are two options by w.hich this review can beaccomplished.
Option 1:

A State may derive and submit each individual water-effect ratio determination toEPA ior review and approval. This would be accomplished through the normal review and revision process usedby aState.
Option 2:

A Statecan amend its water quality standards to provide a formal procedure which includes derivation of water-effect ratios, appropriate definition of sites, and enforceable monitoring provisions to assure that designated uses are

(8115194) 3-43Water Quality Standards Handtxmk -Second Edition

protected. Both this procedure and the resulting criteria would be subject to full public participation requirements. EPA would review andapprove/disapprove this protocol asarevised standard as part of the State’s triennial review/revision. After adoption oftheprocedure, public review of asite-specific criterion could be accomplished in conjunction with the public review required for permit issuance. For public information, EPA recommends that once ayear theState publish alist of site-specific criteria.

An exception to this policy applies tothe waters of the jurisdictions included in the National Toxics Rule. The EPA review isnot required for thejurisdictions included in the National Toxics Rulewhere EPA establishd theprocedure forthe State for application to the criteria promulgated. The National Toxics Rule was a formal rulemaking process (with notice andcomment) in which EPA pre-authorized the useof acorrectly applied water-effect ratio. That sameprocess has not yet taken place in States not included in the National Toxics Rule.

However, the National Toxics Rule does not affect State authority to establish scientifically defensible procedures to determine Federally authorized WERs. to certify those WERs in NPDFS permit proceedings, or to deny their application based on the State’s risk management analysis.

Asdescribed inSection 121.36(b)(iii) ofthewater quality standards regulation (theofficial regulatory reference tothe National Toxics Rule), thewatereffect ratio is a site-specific calculation. As indicated on page 60866 of the preamble to the National Toxics Rule, therule wasconstructed as arebuttabIe presumption. Thewater-effect ratio is assigned a value of 1.Ountil a different watereffect ratio is derived from suitable tests representative of conditions in the affected waterbody. It isthe responsibility of theStateto determine whether to rebut theassumed value of 1.OintheNational Toxics Rule andapply another value ofthewater-effect ratio inorder toestablish
asite-specific criterion. The site-specific criterion isthen usedtodevelop appropriate NPDES permit limits. The rule thus provides a State with the flexibility to derive an appropriate site-specific criterion for specific waterbodies.

As a point of emphasis, although awater-effect ratio affects permit limits for individual dischargers, it is the State in all cases that determines ifderivation ofasite-specific criterion basedonthewater-effect ratio isallowed and it is the State that ensures that the calculations and dataanalysis aredone completely and correctly.

3.7.6 The Resident Species Procedure

The resident Species Procedure for thederivation ofasite-specific criterion accounts for differences in resident species sensitivity d differences in biological availability and/or toxicity ofamaterial due to variability in physical and chemical characteristics of asite water. Derivation of the site-specific criterion maximum concentration (CMC) and site-specific criterion continuous concentration (CCC) are accomplished after the complete acute toxicity minimum datii set requirements have been met by conducting tests with resident species in sitewater. Chronic tests may also be necessary. This procedure is designed tocompensate concurrently for any real differences between the sensitivity range of speciesrepresented inthenational datasetandfor site water which may markedly affect the biological availability and/or toxicity of the material of interest.

Certain families oforganisms have bezn specified intheNational Guidelines acutetoxicity minimum data set (e.g., Salmonidae in fresh water and Penaeidae or Mysidae insaltwater); ifthis orany other requirement cannot be met because the family or other group (e.g., insect or hcnthic crustacean) in fresh water is not represented by resident species, select a substitute(s) from a sensitive family represented by one or more resident species and meet the 8family minimum datasetrequirement. Ifall thefamilies atthesite have been tested and the minimum data set requirements have not been met, use the mostChapter 3-Water Oualim Crireria

sensitive resident family mean acute value asthe site-specific Final Acute Value.

To derive the criterion maximum concentration divide thesite-specific Final Acute Value bytwo. The site-specific Final Chronic Value can be obtained as described in the Appendix L. The lower of thesite-specific Final Chronic Value (as described in the recalculation procedure - Appendix L, p. 90) and the recalculated sitespecific Final Residue Value becomes the sitespecific criterion continuous concentration unless plant or other data (including dataobtained from the site-specific tests) indicates alower value is appropriate. If aproblem isidentified, judgment should be used in establishing the site-specific criterion.

The frequency of testing (e.g., the need for seasonal testing) will berelated tothevariability ofthephysical andchemical characteristics ofsite water as it is expected to affect the biological availability and/or toxicity of the material of interest. As the variability increases, the frequency of testing will increase. Many of the limitations djscussed for the previous two procedures would also apply tothis procedure.



## Endnotes

1.Proceedings in production.

Contact: Ecological Risk Assessment Branch (4304)

U.S. Environmental Protection Agency 401 M Street, S.W. Washington, DC 20460 Telephone (202) 260-1940

(8/15iW) 3-45Chapter4-Antidegradation

CHAPTER 4

ANTIDEGRADATION

(40 CFR 131.12)

Table of Contents

4.1 History of Antidegradation

.................................... 4-1

4.2 Summary of the Antidegradation Policy

............................ 4-1

4.3 State Antidegradation Requirements

............................... 4-2

4.4 Protection of Existing Uses -40 CFR 131.12(a)(1)

..................... 4-3

4.4.1 Recreational Uses

................................... 4-4

4.4.2 Aquatic Life/Wildlife Uses

.............................. 4-5

4.4.3 Existing Uses and Physical Modifications

..................... 4-5

4.4.4 Existing Uses and Mixing Zones

.......................... 4-6

4.5 Protection of Water Quality in High-Quality Waters -30 CFR 131.12(a)(2)

...... 4-6

4.6 Applicability of Water Quality Standards to Nonpoint Sources Versus Enforceability of Controls

............................................. 4-9

4.7 Outstanding National Resource Waters (ONRW) -40 CFR 131.12(a)(3)

....... 4-10

4.8 Antidegradation Application and Implementation

...................... 4-10

4.8.1 Antidegradation, Load Allocation, Waste Load Allocation. Total Maximum

Daily Load, and Permits

.............................. 4-12

4.8.2 Antidegradation and the Public Participation Process

............. 4-13