## EPA United States Office of Water EPA823-B-94-005a EnvironmentalProtection (4305) Agency August 1994 

## Water Quality Standards Handbook:
Second Edition

Contains Update #1 August 1994 to restore and maintain the chemical, physical, andbiologicalintegrityof the Nation’s waters.” Section 101(a)of the CleanWaterAct

## EPA United States EnvironmentalProtection Agency Office of Water EPA-823-B94-005a (4305) August 1994 

## Water Quality Standards Handbook:
Second Edition

Contains Update #1 August 1994 ”

... to restore and maintain the chemical, physical,andbiologicalintegrityof theNation’s waters.” Section101(a)of the CleanWaterAct

## WATER QUALITY STANDARDS HANDBOOK SECOND EDITION

Water Quality StandardsBranch Office of ScienceandTechnology U.S. Environmental Protection Agency Washington, DC 20460
September1993

Contains update#1 August 1994

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## U.S. Environmental Protection Agency Water Resource Center (RC-4100) 401 M Street, SW. Washington, DC 20460Table ofContents
FOREWORD

Dear Colleague: The following document entitled Water Quality Standards Handbook - Second Edition provides guidance issued in support of the Water Quality Standards Regulation (40 CFR 131, as amended). This Handbook includes the operative provisions of the first volume of the Handbook issued in 1983 and incorporates subsequent guidance issued since 1983. The 1993 Handbook contains only final guidance previously issued by EPA - it contains no new guidance. Since the 1983 Handbook has not been updated in ten years, we hope that this edition will prove valuable by pulling together current program guidance and providing a coherent document as a foundation for State and Tribal water quality standards programs. The Handbook also presents some of the evolving program concepts designed to reduce human and ecological risks, such as endangered species protection; criteria to protect wildlife. wetlands. and sediment quality; biological criteria to better define desired biological communities in aquatic ecosystems; and nutrient criteria. This Handbook is intended to serve as a “living document,” subject to future revisions as the water quality standards program moves forward, and to reflect the needs and experiences of EPA and the States. To this end, the Handbook is published in a loose leaf format designed to be placed in three ring binders. This copy of the Handbook includes updated material for 1994 (see Appendix X), and EPA anticipates publishing additional changes periodically and providing them to Handbook recipients. To ensure that you willreceive these updates, please copy the reader response card in Appendix W and mail it to the address on the reverse. The handbook also contains alisting, bytitle and date, oftheguidance issued since the Handbook was first published in1983 that isincorporated inthe Second Edition. Copies ofthese documents areavailable upon request. The Water Quality Standards Handbook - Second Edition provides guidance on the national water quality standards program. EPA regional offices and States may have additional guidance that provides more detail on selected topics of regional interest. For information on regional or State guidance, contact the appropriate regional water quality standards coordinator listed in Appendix U. EPA invites participation from interested parties in the water quality standards program, and appreciates questions on this guidance as well as suggestions and comments for improvement. Questions or comments may be directed to the EPA regional water quality standards coordinators or to: David Sabock, Chief U.S. Environmental Protection Agency Water Quality Standards Branch (4305) 401 M Street, S.W. Washington, D.C. 20460 Telephone (202) 475-7315
Betsy Southerland, Acting Director Standards and Applied Science Division (8/15/94) IIIWater Quality Standards Handbook - Second Edition Note to the Reader The Water Quality Standards Handbook, first issued in 1983, is a compilation of EPA’s guidance on the water quality standards program and provides direction for States in reviewing, revising and implementing water quality standards. The Water Quality Standards Handbook - Second Edition retains all the guidance in the 1983 Handbook unless such guidance was specifically revised in subsequent years. An annotated list of the major guidance and policy documents on the water quality standards program issued since 1983 is included in the Introduction and material added to the Second Edition by periodic updates since 1993 is summarized in Appendix X. Material in the Handbook contains only guidance previously issued by EPA; it contains no new guidance. The guidance contained in each of the documents listed in the Introduction is either: 1) incorporated in its entirety, or summarized, in the text of the appropriate section of this Handbook, or 2) attached as an appendix (see Table of Contents). If there is uncertainty or perceived inconsistency on any of the guidance incorporated into this Handbook, the reader is directed to review the original guidance documents or call the Water Quality Standards Branch at (202) 260-1315. Copies of all original guidance documents not attached as appendices may be obtained from the source listed for each document in the Reference section of this Handbook. Limited free copies of this Handbook may be obtained from: Office of Water Resource Center, RC-4100 U. S. Environmental Protection Agency 401 M Street, S.W. Washington, DC 20460 Telephone: (202) 260-7786 (voice mail publication request line) Copies may also be obtained from: Education Resource Information Center/Clearinghouse for Science, Mathematics and Environmental Education (ERIC) 1929 Kenny Road Columbus, OH 43210-1080 (Telephone: 614-292-6717) (VISA, Mastercard and purchase order numbers from schools and businesses accepted)
U.S. Department of Commerce National Technical Information Service (NTIS) 5285 Port Royal Road Springfield, VA 22161 (Telephone: 1-800-553-6847) (American Express, VISA and Mastercard accepted)

Robert S. Shippen Editor iv (8115194)Table of Contents
TABLE OF CONTENTS

Foreword
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii Note tothe Reader
. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv Table of Contents
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Glossary
. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GLOSS-1 Introduction
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INT-1 History of the Water Quality Standards Program
....................... INT-1 Handbook Changes Since 1983
................................. INT-5 Overview of the Water Quality Standards Program
..................... INT-8 The Role of WQS in the Water Quality Management Program
.............. INT-13 Future Program Directions
................................... INT-14 Chapter 1 - General Provisions (40 CFR 131 - Subpart A) 1.1 Scope-40 CFR 131.1
.................................... 1-1 1.2 Purpose - 40 CFR 131.2
................................... 1-1 1.3 Definitions - 40 CFR 131.3
................................. 1-1 1.4 State Authority - 40 CFR 131.4
.............................. 1-2 1.5 EPA Authority - 40 CFR 131.5.
.............................. 1-3 1.6 Requirements for Water Quality Standards Submission - 40 CFR 131.6
...... 1-4 1.7 Dispute ResoIution Mechanism - 40 CFR 131.7
..................... 1-4 1.8 Requirements for Indian Tribes To Qualify for the WQS Program - 40 CFR 131.8
.. ........................................... 1-9 1.9 Adoption of Standards for Indian Reservation Waters
................ 1-18 Endnotes
................................................ 1-21 Chapter 2 - Designation of Uses (40 CFR 131.10) 2.1 Use Classification - 40 CFR 131.10(a)
.......................... 2-1 2.2 Consider Downstream Uses - 40 CFR 131.10(b)
.................... 2-4 2.3 Use Subcategories - 40 CFR 131.10(c)
.......................... 2-5 2.4 Attainability of Uses
. 40 CFR 131.10(d)
......................... 2-5 2.5 Public Hearing for Changing Uses - 40 CFR 131.10(e)
................ 2-6 2.6 Seasonal Uses - 40 CFR 131.10(f)
............................. 2-6 2.7 Removal of Designated Uses - 40 CFR 131.10(g) and (h)
.............. 2-6 2.8 Revising Uses to Reflect Actual Attainment - 40 CFR 131.10(i)
........... 2-8 2.9 Use Attainability Analyses - 40 CFR 131.10(j) and (k)
................ 2-9

(8/15/94) vChapter 3 - Water Quality Criteria (40 CFR 131.11)

3.1 EPA Section 304(a) Guidance
..................... 32 Relationship of Section 304(a) Criteria to State Designated Uses
......... 3.3 State Criteria Requirements
...................... 3.4 Criteria for Toxicants
.......................... 3.5 Forms of Criteria
............................ 3.6 Policy on Aquatic Life Metals Criteria
............... 3.7 Site-Specific Aquatic Life Criteria
.................. Endnotes
...................................... Chapter 4 - Antidegradation (40 CFR 131.12) 3-1 3-10 3-12 3-13 3-23 3-34 3-38 3-45

4.7 4.8 History of Antidegradation
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1 Summary of the Antidegradation Policy
. . . . . . . . . . . . . 4-1 State Antidegradation Requirements
. . . . . . . . . . . . . . . . . . . . . . . . . . 4-2 Protection of Existing Uses - 40 CFR 131.12(a)(1)
. . . . . . . . . . . . . . . . . . 4-3 Protection of Water Quality in High-Quality Waters - 40 CFR 131.12(a)(2)
. . . . 4-6 Applicability of Water Quality Standards to Nonpoint Sources Versus Enforceability of Controls
. . . . . . . . . . . . . . . . . 4-9 Outstanding National Resource: Waters (ONRW) - 40 CFR 131.12(a)(3)
. . . . 4-10 Antidegradation Application and Implementation
. . . . . . . . . . . . . . . . . . 4-10 Chapter 5-General Policies (40CFR 131.13) 5.1 Mixing Zones
. . . ................. . . . . . 5.2 Critical Low-Flows
. . . . . . . ............... . . . . 5.3 Variances From Water Quality Standards
. . .............. . Chapter 6 - Procedures for Review and Revision of Water Quality Standards

(40 CFR 131 Subpart C) 6.1 State Review and Revision
............................ 6.2 EPA Review and Approval
........................... 6.3 EPA Promulgation
............................... Chapter 7-The Water Quality-based Approach toPollution Control 7.1 Determine Protection Level
........................ 7.2 Conduct Water Quality Assessment
................... 7.3 Establish Priorities
............................. 7.4 Evaluate Water Quality Standards for Targeted Waters
............. 7.5 Define and Allocate Control Responsibilities
.............. 7.6 Establish Source Controls
........................ 7.7 Monitor and Enforce Compliance
................... 7.8 Measure Progress
................................ 5-1 5-9 5-11

6-1 6-8 6-13

7-2 7-3 7-5 7-6 7-7 7-8 7-12 7-13 References
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . REF-1
vi (8/15/94)Table of Contents Appendices: A- Water Quality Standards Regulation - 40 CFR 131. B- Chronological Summary of Federal Water Quality Standards Promulgation Actions. C- Biological Criteria: National Program Guidance for Surface Waters, April 1990. D- National Guidance: Water Quality Standards for Wetlands, July 1990. E- An Approach for Evaluating Numeric Water Quality Criteria for Wetlands Protection, July 1991. F- Coordination Between the Environmental Protection Agency, Fish and Wildlife Service and National Marine Fisheries Service Regarding Development of Water Quality Criteria and Water Quality Standards Under the Clean Water Act, July 1992. G - Questions and Answers on: Antidegradation, August 1985. H- Derivation of the 1985 Aquatic Life Criteria. I- List of EPA Water Quality Criteria Documents. J- Attachments to Office of Water Policy and Technical Guidance on Interpretation and Implementation of Aquatic Life Metals Criteria, October 1993. K- Procedures for the Initiation of Narrative, Biological Criteria, October 1992. L- Interim Guidance on Determination and Use of Water-Effect Ratios for Metals, February 1994. M- Reserved. N- IRIS [Integrated Risk Information System/Background Paper. O- Reserved. P- List of 126 Section 307(a) Priority Toxic Pollutants. Q- Wetlands and 401 Certification: Opportunities and Guidelines for States and Eligible Indian Tribes - April 1989. R- Policy on the Use of Biological Assessments and Criteria in the Water Quality Program, May 1991. S- Reserved. T- Use Attainability Analysis Case Studies. (8/15/94) viiWater Quality Standards Handbook - Second Edition U- List of EPA Regional Water Quality Standards Coordinators. V- Water Quality Standards Program Document Request Forms. W- Update Request Form for Wafer Quality Standards Handbook - Second Edition. X- Summary of Updates

viii (8/15/94)

## GLOSSARY

WATER QUALITY STANDARDS HANDBOOK

SECOND EDITIONGlossary
GLOSSARY

The “Act” refers to the Clean Water Act (Public Law 92-500, as amended (33 USC 1251, et.seq. ) (40 CFR 131.3.) “Acute” refers to a stimulus severe enough to rapidly induce an effect; in aquatic toxicity tests, an effect observed in 96- hours or less is typically considered acute. When referring to aquatic toxicology or human health, an acute affect is not always measured in terms of lethality (USEPA, 1991a.) “Acute-chronic ratio” (ACR) is the ratio of the acute toxicity of an effluent or a toxic-ant to its chronic toxicity. It is used as a factor for estimating chronic toxicity on the basis of acute toxicity data, or for estimating acute toxicity on the basis of chronic toxicity data (USEPA, 1991a.) “Acutely toxic conditions” are those acutely toxic to aquatic organisms following their short-term exposure within an affected area (USEPA, 1991a.) “Additivity” is the characteristic property of a mixture of toxicants that exhibits a total toxic effect equal to the arithmetic sum of the effects of the individual toxicants (USEPA, 1991a.) “Ambient toxicity” is measured by a toxicity test on a sample collected from a water body (USEPA, 1991a.) “Antagonism” is the characteristic property of a mixture of toxicants that exhibits a less-than-additive total toxic effect (USEPA, 1991a.) “Aquatic community” is an association of interacting populations of aquatic organisms in a given water body or habitat (USEPA, 1990; USEPA, 1991a.) “Averaging period” is the period of time over which the receiving water concentration is averaged for comparison with criteria concentrations. This specification limits the duration of concentrations above the criteria (USEPA, 1991a.) “Bioaccumulation” is the process by which a compound is taken up by an aquatic organism, both from water and through food (USEPA, 1991a.) “Bioaccumulation factor” (BAF) is the ratio of a substance’s concentration in tissue versus its concentration in ambient water, in situations where the organism and the food chain are exposed (USEPA, 1991a.) “Bioassay” is a test used to evaluate the relative potency of a chemical or a mixture of chemicals by comparing its effect on a living organism with the effect of a standard preparation on the same type of organism. Bioassays are frequently used in the pharmaceutical industry to evaluate the potency of vitamins and drugs (USEPA, 1991a.)
(9/15/93) GLOSS-1Water Quality Standards Handbook - Second Edition

“Bioavailability” is a measure of the physicochemical access that a toxicant has to the biological processes of an organism. The less the bioavailability of a toxicant, the less its toxic effect on an organism (USEPA, 1991a.) “Bioconcentration” is the process by which a compound is absorbed from water through gills or epithelial tissues and is concentrated in the body (USEPA, 1991a.) “Bioconcentration factor” (BCF) is the ratio of a substance’s concentration in tissue versus its concentration in water, in situations where the food chain is not exposed or contaminated. For non-metabolized substances, it represents equilibrium partitioning between water and organisms (USEPA, 1991a.) “Biological criteria” are narrative expressions or numeric values of the biological characteristics of aquatic communities based on appropriate reference conditions. As such, biological criteria Serve as an index of aquatic community health. It is also known as biocriteria (USEPA, 1991a.) “Biological integrity” is the condition of the aquatic community inhabiting unimpaired water bodies of a specified habitat as measured by community structure and function (USEPA, 1991a.) “Biological monitoring” describes the use of living organisms in water quality surveillance to indicate compliance with water quality standards or effluent limits and to document water quality trends. Methods of biological monitoring may include, but are not limited to, toxicity testing (such as ambient toxicity testing or whole-effluent toxicity testing) and biological surveys. It is also known as biomonitoring (USEPA, 1991a.) “Biological survey or biosurvey” is collecting, processing, and analyzing a representative portion of the resident aquatic community to determine its structural and/or functional characteristics (USEPA. 1991a.) “Biomagnification” is the process by which the concentration of a compound increases in species occupying successive trophic levels (USEPA, 1991a.) “Cancer potency slope factor” (q1*) is an indication of a chemical’s human cancer-causing potential derived using animal studies or epidemiological data on human exposure; based on extrapolation of high-dose levels over short periods of time to low-dose levels and a lifetime exposure period through the use of a linear model (USEPA, 1991a.) “Chronic” defines a stimulus that lingers or continues for a relatively long period of time, often onetenth of the life span or more. Chronic should be considered a relative term depending on the life span of an organism. The measurement of a chronic effect can be reduced growth, reduced reproduction, etc., in addition to lethality (USEPA, 1991a.) “Community component” is a general term that may pertain to the biotic guild (fish, invertebrates, algae), the taxonomic category (order, family, genus, species), the feeding strategy (herbivore, omnivore, predator), or the organizational level (individual, population, assemblage) of a biological entity within the aquatic community (USEPA, 1991a.)

GLOSS-2 (9/15/93)

### Glossan



### “Completely mixed condition” 

## is defined as no measurabledifference in the concentration of a pollutant exists across a 

## transect of the water body (e.g., does not vary by 5%) (LJSITA. 1991a.) “Criteria” 

## areelementsof Statewaterquality standards, expressed asconstituentconcentrations,levels, or narrative statements,representinga quality of water that supports a particular use. When criteria are met, water quality will generally protect the designateduse(40 CFR 131.3.) “Criteria continuous concentration” (CCC) 

## isthe EPA nationalwaterquality criteria recommendation for the highest instream concentrationof a toxicant or an effluent to which organisms can be exposedindefinitely without causingunacceptable effect (USEPA, 1991a.) “Criteria maximum concentration” (CMC) 

## isthe EPA national 

## water quality criteria recommendation for the highest instream concentrationof a toxicant or an effluent to which organisms can be exposedfor a brief period of time without causingan acuteeffect (USEPA, 1991a.) “Critical life stage” 

## is the period of time in an organism’s lifespan in which it is the most susceptible to adverseeffects causedby exposure to toxicants, usually during early development (egg, embryo, larvae). 

## Chronic toxicity tests are often run on critical life stagesto replace long duration, life cycle testssince 

## the most toxic effect usually occursduring the critical life stage (USEPA, 

## 1991a.) “Critical species” 

## isaspecies that is commercially or recreationally important at thesite, aspecies that exists at the site and is listed asthreatenedor endangeredunder section4 of the Endangered SpeciesAct, or a speciesfor which there is evidence 

## that the lossof the speciesfrom the site is likely to cause 

## anunacceptableimpacton acommercially or recreationally important species, athreatenedor endangered species,theabundances

of avariety of otherspecies,or thestructure or function of the community (USEPA, 1994a.) “Design flow" 

## is the flow usedfor steady-state waste load allocation modeling (USEPA, 1991a.) 

### “Designated 

## uses” are thoseusesspecified in water quality standardsfor eachwater body or segment whether 

## or not they are being attained(40 CFR 131.3.) “Discharge length scale” 

## isthesquareroot of thecross-sectional areaof anydischargeoutlet (USEPA, 1991a.) “Diversity” is 

## the number andabundanceof biological taxa in a specified location (USEPA, 1991a.) “Effective concentration” (EC) 

## is a point estimateof the toxicant concentrationthat 

## would causean observableadverseeffect (suchasdeath, immobilization, or serious incapacitation) in a given percentageof the test 

## organisms(USEPA, 1991a.) “Existing 

## uses” are thoseusesactually attained in the water body on or after November 28, 1975, 

## whether or not they are included in the water quality standards(40 CFR 131.3.)

(8/15/94) 

### GLOSS-3

## Water

Quality Standards

Handbook - SecondEdition 

### “Federal Indian Reservation, ” “Indian Reservation,” or “Reservation” 

## is defined as 

## all land within the limits of any Indian reservation under thejurisdiction of the United StatesGovernment, notwithstanding the issuanceof any patent, and including rights-of-way running through the reservation (40 CFR 131.3.) “Final acute value” 

## (FAV) is an estimate of the concentration of the toxicant corresponding to a cumulative probability of 0.05 in the acutetoxicity valuesfor all generafor which acceptable acutetestshavebeenconductedon the toxicant (USEPA, 1991a.) “Frequency” 

## is how often criteria can be exceededwithout unacceptablyaffecting the community (USEPA, 1991a.) “Harmonic mean 

## flow” is the number of daily flow measurementsdivided by the sum of the reciprocalsof theflows. That is, it isthereciprocalof themeanof reciprocals(USEPA, 1991a.) “Indian Tribe” or “Tribe” 

## describesany Indian Tribe, band, group, or community recognizedby the Secretaryof the Interior andexercisinggovernmentalauthority overa FederalIndian reservation (40 CFR 131.3.) “Inhibition concentration” 

## (IC) is a point estimateof the toxicant concentrationthat would causea given percent reduction (e.g., IC25) in a non-lethal biological measurement of the test organisms, suchas reproduction or growth (USEPA, 1991a.) “Lethal concentration” 

## is the point estimateof the toxicant concentrationthat would be lethal to a given percentageof the testorganismsduring a specified period (USEPA, 1991a.) “Lipophilic” 

## is a high affinity for lipids (fats) (USEPA, 1991a.) “Load allocations” 

## (LA) the portion of a receiving water TMDL that is attributed either lo one of its existing or future nonpoint sourcesof pollution or to natural 

## background sources(USEPA, 1991a.) “Lowest-observed-adverse-effect-level” 

## (LOAEL) isthelowestconcentrationof aneffluent or toxicant that resultsin statistically significant 

## adversehealtheffectsasobservedin chronic or subchronic humanepidemiology studiesor animal exposure(USEPA, 1991a.) “Magnitude” 

## is how much of a pollutant (or 

## pollutant parameter such as toxicity), expressedas a concentrationor toxic unit is allowable (USEPA, 1991a.) “Minimum level” (ML) 

## refersto the level atwhich theentire analytical systemgivesrecognizablemass spectraand acceptablecalibration points when analyzing for pollutants of concern. This level correspondsto the lowest point at which the calibration curve is 

## determined (USEPA, 1991a.) “Mixing zone” 

## is anareawhereaneffluent dischargeundergoes 

## initial dilution andisextendedto cover the secondarymixing in the ambient 

## water body. A mixing zone is an allocated impact zone where water quality criteria can be exceededas long asacutely toxic conditions are prevented (USEPA, 1991a.) GLOSS-4 (8/15/94)

### Glossary



### “Navigable waters” 

## refer to the waters of the United States, including the territorial seas(33 USC 1362.) “No-observed-adverse-effect-level” (TVOAEL) 

## isatesteddoseof aneffluent or atoxicant below which no adverse biological effects are observed, as identified from chronic or subchronic human epidemiology studiesor animal exposurestudies(USEPA, 1991a.) “No-observed-effect-concentration” (NOEC) 

## is the highest testedconcentration of an effluent or a toxicant at which noadverse effectsareobservedontheaquatictestorganismsat aspecific time of observation. Determined using hypothesistesting (USEPA, 1991a.) “Nonthreshotd 

## effects” are associated with exposureto chemicalsthat have no safeexposure levels. (i.e., cancer) (USEPA, 1991a.) “Persistent pollutant” 

## is not subjectto decay, degradation,transformation, volatilization, hydrolysis, or photolysis (USEPA, 1991a.) “Pollution” 

## is defined asthe man-madeor man-inducedalteration of the chemical, physical, biological and radiological integrity of water (33 USC 1362.) “Priority 

## po1Mant.s” are thosepollutants listed by the Administrator under section307(a) of the Act (USEPA, 1991a.) “Reference ambient concentration” 

## (RAC) is theconcentrationof a chemical in water which will not causeadverseimpactsto human health; RAC is expressedin units of mg/l (USEPA, 1991a.) “Reference conditions” 

## describethe characteristicsof water body segmentsleast impaired by human activities. As such,referenceconditions canbeusedto describeattainablebiological or habitat conditions for water body segmentswith common watershed/catchmentcharacteristicswithin defined geographical regions. “Reference tissue concentration” (RTC) 

## is the concentrationof a chemical in edible fish or shellfish tissuewhich will not causeadverseimpactsto human health when ingested. RTC is expressed in units of mg/kg (USEPA, 1991a.) “Reference dose” (Rfl)) 

## is an estimateof the daily exposureto human population that is likely to be without appreciablerisk of deleteriouseffectduring a lifetime; derivedfrom NOAEL or LOAEL (USEPA, 1991a.) “Section 304(a) criteria” 

## are developedby EPA underauthority of section304(a)of theAct basedon the latestscientific information on the relationship that the effect of a constituentconcentration hason particular aquaticspeciesand/or human health. This information is issuedperiodically to the Statesasguidancefor usein developing criteria (40 CFR 131.3.) “Site-specific aquatic life criterion” 

## is a water quality criterion for aquatic life that hasbeenderived to be specifically appropriate to the water quality characteristicsand/or speciescomposition at a particular location (USEPA, 1994a.) (8/15/94) 

## GLOSS-S

### ater Quality StandardsHandbook

### - Second 

### Edition

“States” 

## include: the 50 States,the District of Columbia, Guam, the Commonwealth of Puerto Rico, Virgin Islands, American Samoa, the Trust Territory of the Pacific Islands, and the Commonwealth of the Northern Mariana Islands,andIndian Tribes that EPA determinesqualify for treatment as Statesfor the purposesof water quality standards(40 CFR 131.3.) “Steady-state model” 

## is a fate and transport model that usesconstantvalues of input variables to predict constant 

## valuesof receiving water quality concentrations(USEPA, 1991a.) “STORET” 

## is EPA’s computerized water quality databasethat includes physical, chemical, and biological data measuredin water bodiesthroughout the United States(USEPA, 1991a.) “Sublethal” 

## refers to a stimulus below the level that causes 

## death(USEPA, 1991a.) “Synergism” 

## isthecharacteristicproperty of amixture of toxicantsthatexhibits agreater-than-additive total toxic 

## effect (USEPA, 1991a.) “Threshold 

## effects” result from chemicals that have a safe level (i.e.. acute, subacute,or chronic human health effects) (USEPA, 1991a.) “Total maximum daily load” (TMDL) 

## isthesumof the 

## individual wasteloadallocations (WLAs) and load allocations (LAS); a margin of safety is included with the two typesof allocations sothat any additional loading, regardlessof source, would not produce a violation of water quality standards(USEPA, 1991a.) “Toxicity test” 

## is a procedure to determine the toxicity of a chemical or an effluent using living organisms. A toxicity testmeasures thedegreeof effect on exposed 

## testorganismsof a specific chemical or effluent (USEPA, 1991a.) “Toxic pollutant” 

## refers to those pollutants, or combination of pollutants, including disease-causing agents,which after dischargeanduponexposure,ingestion, inhalation, or assimilation into any organism. either directly from the environment or 

## indirectly by ingestion through food chains, will. or on the basis of information available to the administrator, cause death, disease, behavioral abnormalities, cancer, genetic mutations, physiological malfunctions (including malfunctions in reproduction) or physicaldeformations, in suchorganismsor their offspring (33 llSC section 1362.) “Toxic units” (TUs) 

## are a measureof toxicity in aneffluent asdeterminedby the acutetoxicity units (T1’a) or chronic toxicity units (TUc) measured(USEPA, 1991a.) “Toxic unit acute” 

## (TUa) is the reciprocal of the effluent concentrationthat causes50 percent of the organismsto die by the end of the acuteexposureperiod (i.e., lOO/LC& (USEPA, 1991a.) “Toxic unit chronic” (TUc) 

## is the reciprocal of the effluent concentrationthat causes 

## no observable effect on 

## the test organisms by the end of the chronic exposure period (i.e., lOO/NOEC) (ITSEPA. 1991a.)

GLOSS-6 (8/15/94)

### Glossay



### “Use attainability 

## analysis” (UAA) is a structured scientific assessment of the factors affecting the 

## attainment of the usewhich may include 

## physical, chemical, biological, and economic factors asdescribed in section 131.10(g) (40 CFR 131.3.) “Waste load allocation” (WLA) 

## is the portion of a receiving water’s TMDL that is allocated to 

## one of its existing or future point sourcesof pollution (USEPA, 1991a.) “Waters of the United States” 

## refer to: 

## (1)
(2) 

## (3)

(4) (5) (6) 

## (7) all waterswhich arecurrently used,were usedin the past, or may besusceptibleto use in interstateor foreign commerce, including all waterswhich are subjectto the ebb and flow of the tide; all interstatewaters, including interstatewetlands; all other waterssuchasintrastatelakes, rivers, streams(including intermittent streams). mudflats, sandflats, wetlands, sloughs, prairie potholes. wet meadows, playa lakes. or natural pondsthe useor degradationof which would affect or could affect interstate or 

## foreign commerce, including any suchwaters: (9 which are or could be usedby interstateor foreign travelers for 

## recreational or other 

## purposes; (ii) from which fish or shellfish areor could betakenandsold in interstateor foreign commerce; or (iii) which are or could be used for industrial purposes by industries in 

## interstate commerce. all impoundmentsof watersotherwise defined aswaters of the United Statesunder this definition; tributaries of waters in paragraphs(1) through (4) of this definition; the territorial sea;and wetlands adjacentto waters (other than waters that are themselveswetlands) identified 

## in paragraphs(1) through (6) of this definition. “Wetlands” are defined as thoseareas that are inundatedor saturatedby surfaceor groundwater at a frequency and duration 

## sufficient to support, and that under normal circumstancesdo support, a prevalence of 

## vegetation typically adaptedfor life in saturatedsoil conditions. Wetlands generalI) include swamps, marshes,bogs, and similar areas. Waste treatment systems, including treatment ponds or lagoons 

## designed to meet the 

## requirementsof the Act (other than cooling pondsasdefined in 40 CFR 423. I l(m) which also meet the criteria for this definition) are not watersof the United States.(40 CFR 232.2.)
(8/15/W) 

## GI,OSS-7

### WaterQuality StandardsHandbook- SecondEdition



### “Water-effect ratio” (WER) 

## is anappropriatemeasureof thetoxicity of a material obtained in a site water divided by the samemeasureof the toxicity of the samematerial obtained simultaneously in a laboratory dilution water (USEPA, 1994a.) “Water quality assessment” 

## is anevaluationof 

## thecondition of awater body usingbiological surveys, chemical-specific analysesof pollutants in water bodies, 

## and toxicity tests(USEPA, 1991a.) “Water quality limited segment” 

## refersto any segmentwhere it is known that 

## water quality doesnot meet applicable water quality standards and/or 

## is not expectedto meetapplicable water quality standardseven after application of technology-basedeffluent limitations required by sections 301(b)(l)(A) and (B) and 306 

## of the Act (40 CFR 131.3.) “Water quality standards” (WQS) 

## areprovisionsof Stateor Federallaw which consistof adesignated useor usesfor the watersof the United States,waterquality criteria for suchwatersbasedupon suchuses. Water quality standards areto protect public health or welfare, enhancethe quality of the water and servethe purposesof the Act (40 CFR 131.3.) “Whok-efIluent toxicity” 

## is the total toxic effect of an effluent measureddirectly with a toxicity test (USEPA, 1991a.)

GLOSS-8 (8/15/!-M)