Water Quality Standards (2025)

Tribal code

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Text

Water Quality Standards

for the

Walker River Paiute Tribe

Schurz, Nevada

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TABLE OF CONTENTS

Water Quality Standards for the Walker River Paiute Tribe, Schurz, Nevada ......... 1

(a) Introduction. ................................................................................................................ 4

(b) Definitions .................................................................................................................... 5

(c) Designated uses: ........................................................................................................... 9

(d) Narrative water quality criteria ................................................................................. 10

(e) Numeric water quality criteria ................................................................................... 11

(f) Antidegradation policy ................................................................................................ 12

(g) Antidegradation implementation methods within the WRPT Reservation .............. 13

(h) Wetlands designated uses, narrative and numeric water quality criteria, and

antidegradation requirements:................................................................................................ 17

(i) Mixing Zone Policy (Reserved) ................................................................................. 19

(j) Compliance schedule authorizing provision .............................................................. 20

(k) WQS variance authorizing provision ........................................................................ 21

(l) Water Body-Specific designated uses, criteria, and WQS variances ........................ 22

(m) Tables ........................................................................................................................ 23

Table 1. Aquatic Life Criteria................................................................................................ 24

Table 1a: Conversion Factors for Dissolved Metals Criteria.................................................... 27

Table 1b: Parameters for Calculating Freshwater Dissolved Metals Criteria That Are

Hardness-Dependent ................................................................................................................. 28

Table 2. Copper Aquatic Life Criteria for Fresh Waters .......................................................... 29

Table 3. Selenium Aquatic Life Criteria for Fresh Waters ....................................................... 30

Table 4. Ammonia Aquatic Life Criteria for Fresh Waters ...................................................... 31

Table 5. Human Health Criteria............................................................................................ 32

Footnotes:................................................................................................................ 38

Table 6. Recreational Water Quality Criteria ........................................................................... 39

Table 7. Design Flows .............................................................................................................. 39

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(a) Introduction.

These water quality standards apply to all fresh surface waters of the Walker River, home of the

Walker River Paiute Tribe (WRPT) Reservation, including associated floodplains and wetlands.

The reservation was established in 1874 by Executive Order and is under the General Allotment

Act of 1887. The Walker River Paiutes were originally known as the Agai-Dicutta “Trout

Eaters”.

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(b) Definitions

(1) “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.

(2) “Aquatic community” is an association of interacting populations of aquatic organisms in

a given water body or habitat.

(3) “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.

(4) “Best management practices” or “BMP” means physical, structural, and/or managerial

practices that, when used singularly or in combination, prevent or reduce pollution.

(5) “Bioaccumulation” is the process by which a compound is taken up by an aquatic organism,

both from water and through food.

(6) “Biological integrity” is the condition of the aquatic community inhabiting unimpaired

water bodies of a specified habitat as measured by community structure and function.

(7) “Chronic” defines a stimulus that lingers or continues for a relatively long period of time,

often one tenth 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.

(8) “Clean Water Act” or “CWA” means the federal Clean Water Act, 33 U.S.C. §§ 12511387, as amended.

(9) “Compliance schedule” means a schedule of remedial measures, including an enforceable

sequence of actions or operations, leading to compliance with an effluent limitation or other

limitation, prohibition or standard.

(10) “Criteria” are elements of the WRPT’s water quality standards, expressed as constituent

concentrations, levels, or narrative statements, representing a quality of water that supports a

particular use. When criteria are met, water quality will generally protect the designated use.

(11) “Criteria continuous concentration” (CCC) is the highest instream concentration of a

toxicant or an effluent to which organisms can be exposed indefinitely without causing

unacceptable effect.

(12) “Criteria maximum concentration” (CMC) is the highest instream concentration of a

toxicant or an effluent to which organisms can be exposed for a brief period of time without

causing an acute effect.

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(13) “Cyanotoxins” are toxins produced by cyanobacteria. Cyanobacteria, a type of

phytoplankton also known as blue-green algae, are often the cause of algal blooms in fresh

water and occasionally in marine water. Their toxins can harm people, animals, aquatic

ecosystems, the economy, drinking water supplies, property values, cultural activities, and

recreational activities, including swimming and fishing.

(14) “Design flow" is the flow used for steady-state waste load allocation modeling.

(15) “Designated uses” are those uses specified in water quality standards for each water body

or segment whether or not they are being attained.

(16) “Diversity” is the number and abundance of biological taxa in a specified location.

(17) “E. coli or Escherichia coli” is the name of a specific bacterium used as an indicator of

fecal (pathogen) pollution in fresh water environments and is expressed as colony forming

units (cfu) per 100 milliliters or most probable number (mpn) per 100 milliliters. Analytic

procedures include multiple-tube fermentation and membrane filter techniques. Elevated levels

can be an indicator of the presence of pathogens that can cause human health problems.

(18) “Existing uses” are those uses actually attained in the water body on or after November

28, 1975, whether or not they are included in the water quality standards.

(19) “Federal Indian Reservation,” “Indian Reservation,” or “Reservation” is defined as all

land within the limits of any Indian reservation under the jurisdiction of the United States

Government, notwithstanding the issuance of any patent, and including rights-of-way running

through the reservation.

(20) “Frequency” is how often criteria can be exceeded without unacceptably affecting the

community.

(21) “Geometric mean” (GM) refers to the Nth root of the product of N numbers. Alternatively,

the geometric mean can be calculated by adding the logarithms of N numbers, dividing the

sum by N, and taking the antilog of the quotient. The geometric mean of two numbers is the

square root of the product of the two numbers, and the geometric mean of one number is that

number. Either natural (base e) or common (base 10) logarithms can be used to calculate

geometric means as long as they are used consistently within each set of data, i.e., the antilog

used must match the logarithm used.

(22) “Harmonic mean flow” is the number of daily flow measurements divided by the sum of

the reciprocals of the flows. That is, it is the reciprocal of the mean of reciprocals.

(23) “Indian Tribe” or “Tribe” describes any Indian Tribe, band, group, or community

recognized by the Secretary of the Interior and exercising governmental authority over a

Federal Indian reservation. The use of the word Tribe herein is meant to refer to the Walker

River Paiute Tribe (WRPT).

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(24) “Magnitude” is how much of a pollutant (or pollutant parameter such as toxicity),

expressed as a concentration or toxic unit is allowable.

(25) "Nonpoint source" means any dispersed land-based or water-based activity rather than a

point source that contributes to water quality degradation, including but not limited to,

atmospheric deposition; surface water runoff from agricultural, urban, forest, construction and

mining lands; subsurface or underground sources; or discharges from boats or marine vessels

not otherwise regulated under the National Pollutant Discharge Elimination System program.

(26) “NPDES” means National Pollutant Discharge Elimination System, the national program

for issuing, modifying, revoking and reissuing, terminating, monitoring and enforcing permits,

and imposing and enforcing pretreatment requirements, under CWA § 307, 318, 402, and 405

of the CWA.

(27) “Outstanding National Resource Water” is a high quality water that constitutes an

outstanding Tribal resource due to its extraordinary water quality or ecological values, or

where special protection is needed to maintain critical habitat areas.

(28) “Permit” means a document issued pursuant to Tribal code or federal laws (such as CWA

§§ 401, 402 and 404) specifying waste treatment and control requirements or discharge

conditions.

(29) “Point source” means any discernible, confined or discrete conveyance, including, but not

limited to, any pipe, ditch, channel, sewer, tunnel, conduit, well, discrete fissure, container,

confined animal feeding operation, vessel, or other floating craft, from which pollutants are or

may be discharged.

(30) “Pollutant” means dredged spoil, solid waste, incinerator residue, filter backwash, sewage,

garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive

materials (except those regulated under the Atomic Energy Act of 1954, as amended (42 U.S.C.

2011 et seq.)), heat, wrecked or discarded equipment, rock, sand, cellar dirt and industrial,

municipal, and agricultural waste discharged into water.

(31) “Pollution” is defined as the man-made or man-induced alteration of the chemical,

physical, biological and radiological integrity of water.

(32) “Practicable” means technologically possible, able to be put into practice, and

economically viable.

(33) “Priority pollutants” are those pollutants listed under section 307(a) of the CWA.

(34) “Site-specific criterion” is a water quality criterion that has been derived to be specifically

appropriate to the water quality characteristics and/or species composition at a particular

location.

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(35) “Statistical threshold value” (STV) refers to the approximation of the 90th percentile of

the water quality distribution and is intended to be a value that should not be exceeded by more

than 10 percent of the samples taken.

(36) “Total maximum daily load” (TMDL) is the sum of the individual waste load allocations

(WLAs) and load allocations (LAS); a margin of safety is included with the two types of

allocations so that any additional loading, regardless of source, would not produce a violation

of water quality standards.

(37) “Toxicity test” is a procedure to determine the toxicity of a chemical or an effluent using

living organisms. A toxicity test measures the degree of effect on exposed test organisms of a

specific chemical or effluent.

(38) “Toxic pollutant” refers to those pollutants, or combination of pollutants, including

disease-causing agents, which after discharge and upon exposure, 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 physical deformations, in such

organisms or their offspring.

(39) “Turbidity” means the clarity of water expressed as nephelometric turbidity units (NTU)

and measured with a calibrated turbidity meter.

(40) “Use attainability analysis” (UAA) is a structured scientific assessment of the factors

affecting the attainment of the use which may include physical, chemical, biological, and

economic factors as described in 40 CFR section 131.10(g).

(41) “Whole effluent toxicity” (WET) means the aggregate toxic effect of an effluent measured

directly by a toxicity test.

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The following designated uses shall apply to all waters included in paragraph (a), except wetlands

as defined in paragraph (h):

(1) Aquatic life, including organism consumption - Water quality must provide for the

protection and propagation of fish shellfish and wildlife;

(2) Recreation - Water quality must provide for recreation in and on the water;

(3) Cultural and traditional - Water quality must provide for cultural and traditional uses of

the reservation waters; and

(4) Water supply - Water quality must provide for use of the water as a drinking water

source.

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(d) Narrative water quality criteria

(1) General requirements. All waters included in paragraph (a) shall be free from toxic,

radioactive, conventional, non-conventional, deleterious or other polluting substances in

amounts that will prevent attainment of the designated uses specified in paragraph (c).

(2) Aesthetic qualities and protection of aquatic life and human health. All waters included

in paragraph (a) must be capable of supporting aquatic life uses identified in paragraph (c),

and shall be free from substances, attributable to wastewater discharges or any other pollutant

sources, that:

(i) Settle to form objectionable deposits;

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

(iii) Produce objectionable color, odor, taste, or turbidity;

(iv) Cause injury to, are toxic to, or produce adverse physiological responses in humans,

animals, or plants; and/or

(v) Produce undesirable or nuisance aquatic life.

(3) Protection of cultural and traditional uses. All waters with the cultural and traditional

designated use specified in paragraph (c)(3) shall be free from contaminants at levels that

cause or contribute to an impairment in water-based activities essential to maintaining the

Tribe’s cultural and traditional practices.

(4) Downstream protection. All waters designated in paragraph (a) shall maintain a level of

water quality that provides for the attainment and maintenance of the water quality standards

of downstream waters, including the downstream waters of a state or another federallyrecognized tribe.

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(e) Numeric water quality criteria

(1) Aquatic life criteria. The aquatic life criteria for these water quality standards are contained

in Tables 1, 1a, 1b, 2, 3, and 4. The aquatic life criteria apply as follows:

(i) The aquatic life criteria in Tables 1, 1a, 1b, 2, 3, and 4 apply to all waters designated

for the protection and propagation of fish shellfish and wildlife in paragraph (c).

(2) Human health criteria. The human health criteria for these water quality standards are

contained in Table 5.

(i) The human health criteria for carcinogens in Table 5 were calculated based on an

excess lifetime cancer risk level of 1 in 1,000,000.

(ii) The human health criteria in these standards were calculated using a fish consumption

rate of 22 grams per day (gpd).

(iii) For all waters with the Water Supply designated use specified in paragraph (c) (water

supply use), the human health criteria for “Water Plus Organisms” and the methylmercury

“Organisms Only” criterion as presented in Table 5 apply.

(iv) For all waters with the Aquatic Life designated use specified in paragraph (c) (aquatic

life, including organism consumption), but without the designated use Water Supply

specified in paragraph (c) (water supply), the human health criteria for “Organisms Only”

as presented in Table 5 apply.

(3) Recreational water quality criteria. For all waters with the Recreation designated use

specified in paragraph (c) (recreation in and on the waters), the criteria in Table 6 shall apply.

Additionally, the concentration of total microcystins shall not exceed 8 µg/L in more than three

ten-day periods per recreational season, for more than one recreational season, over a five-year

period and the concentration of total cylindrospermopsin shall not exceed 15 µg/L in more than

three ten-day periods per recreational season, for more than one recreational season, over a

five-year period.

(4) Temperature Criteria. Between November to March the temperature should be less than

or equal to 13 degrees centigrade. Between April and June the temperature should be less than

or equal to 23 degrees centigrade. Between July through October the temperature should be

less than or equal to 28 degrees centigrade.

(5) Design flows. The design flows in Table 7 shall be used to implement the aquatic life and

human health criteria in paragraph (e).

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(f) Antidegradation policy

(1) Existing instream water uses and the level of water quality necessary to protect the existing

uses shall be maintained and protected.

(2) Where the quality of the waters exceeds levels necessary to support the protection and

propagation of fish, wildlife, and recreation in and on the water, that quality shall be maintained

and protected unless the WRPT finds, after full opportunity for intergovernmental coordination

and public involvement, that allowing lower water quality is necessary to accommodate

important economic or social development in the area in which the waters are located. In

allowing such degradation or lower water quality, the WRPT shall assure water quality

adequate to protect existing uses fully. Further, the WRPT shall assure that there shall be

achieved the highest statutory and regulatory requirements for all new and existing point

sources and all cost-effective and reasonable best management practices for nonpoint source

control.

(i) Identification of reservation waters for the protections described in paragraph (f)(2) will

be made on a parameter by parameter basis.

(ii) Before allowing any lowering of high quality water, pursuant to paragraph (f)(2), the

Tribe shall find, after an analysis of alternatives, that such a lowering is necessary to

accommodate important economic or social development in the area in which the waters

are located. The analysis of alternatives shall evaluate a range of practicable alternatives

that would prevent or lessen the degradation associated with the proposed activity. When

the analysis of alternatives identifies one or more practicable alternatives, the Tribe shall

only find that a lowering is necessary if one such alternative is selected for

implementation.

(3) Where high quality waters constitute an outstanding Tribal resource, such as waters of

National and Tribal parks and wildlife refuges and waters of exceptional recreational,

ecological, or cultural significance, that water quality shall be maintained and protected.

(4) In those cases where potential water quality impairment associated with a thermal

discharge is involved, the decision to allow such degradation shall be consistent with section

316 of the Clean Water Act.

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(g) Antidegradation implementation methods within the WRPT Reservation

(1) Applicability. The antidegradation policy in paragraph (f) and these antidegradation

implementation methods shall be applied to all reservation waters of the United States

included in paragraph (a).

(i) The requirements of paragraphs (f) and (g) shall be followed when considering all

requests to authorize new or expanded regulated activities. Regulated activities include,

but are not limited to, any activity that requires a permit, license, or water quality

certification pursuant to sections 401, 402, and 404 of the CWA.

(ii) Antidegradation protections will be addressed in new or reissued general permits

authorized, implemented, or administered by the permitting authority either at the time

the permitting authority develops and issues the general permit or upon review of an

applicant’s request to be covered by a general permit. The permitting authority will

describe, in writing in the permit fact sheet, how the general permit is consistent with the

antidegradation requirements of this paragraph and the antidegradation policy in

paragraph (f).

(2) Existing instream use protection consistent with paragraph (f)(1). For all waters, the

Tribe shall ensure that the level of water quality necessary to protect existing uses is

maintained. In order to achieve this requirement, the Tribe shall consider whether a regulated

activity would lower the water quality to the extent that it would no longer be sufficient to

protect and maintain the existing uses of that water body. If the lowering of water quality

would not protect and maintain the existing uses of that water body, then the Tribe will not

allow the lowering of water quality. Such consideration shall be based on all existing and

readily available water quality-related data and information, as well as any additional waterquality related data and information submitted during the public comment period for the

authorization.

(3) High Quality Water Protection consistent with paragraph (f)(2) of this section. In

determining which waters will receive high quality water protection consistent with

paragraph (f)(2), the Tribe will identify high quality water on a parameter-by-parameter

basis. Each parameter that is determined to be high quality shall be considered and evaluated

independently, consistent with this paragraph (g)(3), at the time an applicant requests

authorization to lower high water quality. A parameter is high quality if its water quality

level exceeds its water quality criterion in paragraph (d) and (e). The Tribe shall ensure that

no regulated activity that results in a lowering of water quality occurs unless the components

outlined in paragraph (g)(3)(i) are available to the Tribe and the Tribe has made a finding

consistent with paragraph (g)(3)(ii).

(i) When determining whether to authorize a lowering of water quality for one or more

parameters that exceeds levels necessary to support the protection and propagation of

fish, and wildlife and recreation in and on the water, the Tribe will consider the following

components and information:

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(1) Identifying Information. Name of the applicant, a description of the nature of the

applicant's business and the pollutants to be discharged, location of the discharge, the

name of and any water quality data for the receiving water body, daily maximum and

average flow to be discharged, and effluent characterization.

Alternatives to consider include (only if warranted and as applicable):

•

Alternative methods of production or operation;

Water conversation practices;

Wastewater minimization technologies;

Improved wastewater treatment facility operation;

Alternative methods of treatment, including advanced treatment beyond

applicable technology requirements of the Clean Water Act;

Relocation or configuration of outfall or diffuser;

Process changes/improved efficiency that reduces pollutant discharge;

Seasonal discharge to avoid critical time period for water quality;

Non-discharge alternatives such as land application; and,

Offsets to the activity or discharge’s effect on water quality.

(2) Analysis of alternatives. Identification and evaluation of a range of practicable (as

defined at (b)(34)) alternatives that would prevent or lessen the degradation

associated with the proposed activity to determine whether the degradation of water

quality is necessary. When the analysis of alternatives identifies one or more

practicable alternatives, the Tribe shall only find that a lowering of high water quality

is necessary, consistent with paragraph (f)(2)(ii), if one such alternative is selected for

implementation.

(3) Socio-economic analysis. Identification and evaluation of the social and economic

development benefits to the area in which the waters are located that will be foregone

if the lowering of water quality is not allowed. Along with the analysis of alternatives,

the socio-economic analysis is used to determine whether the lowering of high water

quality will accommodate important economic and social development in the area in

which the water is located. The “area in which the waters are located” shall be

determined on a case-by-case basis and shall include all areas directly impacted by

the proposed regulated activity. Factors that must be considered in the socioeconomic analysis include, but are not limited to, the ecological and economic

importance of the affected waters, the importance of the development to the affected

community, and the socio-economic health of the affected community as determined

by appropriate analytical methods.

(4) Any additional documentation requested by the Tribe which, in the judgment of

the Tribe, is needed to decide whether to find that a lowering of water quality is

necessary to accommodate important economic and social development in the area in

which the water is located.

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(ii) Once the Tribe has the components and information required in paragraph (g)(3)(i),

the Tribe shall use that information to make a finding as to whether the lowering of water

quality is necessary to accommodate important social and economic development in the

area in which the water is located.

(1) If the proposed lowering of high water quality is either not necessary, or not

important to accommodate social and economic development, the Tribe shall deny the

request to lower water quality.

(2) If the lowering of high water quality is necessary to accommodate important

social and economic development goals, the Tribe may allow a lowering to the high

quality water as long as one of the alternatives identified in paragraph (g)(3)(i)(2) is

selected for implementation and incorporated into the authorization for the activity. If

no practicable alternative was identified by the analysis of alternatives, but the

lowering of high water quality will accommodate important social or economic

development the Tribe may allow the lowering of high water quality. If a nondegrading practicable alternative is selected, no lowering of the high quality water

will occur, and the Tribe does not need to allow the lowering.

(3) In no event will the Tribe allow water quality to be lowered below the level

required to fully protect existing and designated uses.

(4) To ensure the opportunity for public involvement, the Tribe shall provide public

notice and request public comment on the preliminary decision to allow a lowering of

high water quality. The preliminary decision will provide relevant information

regarding the lowering of high water quality, including the alternatives analysis,

socio-economic analysis, the estimated amount of assimilative capacity available in

the water body, and the estimated amount of assimilative capacity to be utilized by

the proposed activity. To the extent possible, public notice regarding the finding to

allow a lowering of water quality will be coordinated with other required notices for

public review.

(5) To fulfill intergovernmental coordination, the Tribe shall notify local, state, and

federal agencies that operate in the area impacted by the activity and request

comment on the preliminary decision to allow a lowering of water quality in a high

quality water based on whether it is necessary to accommodate important social and

economic development in the area of the waters impacted by the activity.

(6) Before allowing any degradation of water quality, the Tribe shall identify point

sources and tribal-regulated nonpoint sources that discharge to, or otherwise impact,

the receiving water. The Tribe shall coordinate with other agencies, as necessary, to

assure compliance with the highest statutory and regulatory requirements for all new

and existing point sources and/or all tribal required cost-effective and reasonable best

management practices for non-point source control. If compliance with the highest

statutory and regulatory requirements for all new and existing point sources and all

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point sources cannot be assured, the Tribe will not allow a lowering of high water

quality.

(4) Outstanding Tribal resource water protection consistent with paragraph (f)(3). For

reservation waters assigned as outstanding Tribal resource waters, the Tribe shall ensure,

through the application of appropriate controls on point and tribal regulated nonpoint

pollutant sources, that water quality is maintained and protected. No new or expanded point

source discharges will be allowed to outstanding Tribal resource waters unless it is on a short

term and temporary basis, consistent with paragraph (g)(4)(iii).

(i) Any person or entity may nominate a specific reservation water to be assigned as an

outstanding Tribal resource water. The person or entity may transmit a written

nomination to the Tribe, at any time, including why the reservation water warrants

outstanding Tribal resource protection. The Tribe shall determine whether the nominated

water qualifies as an outstanding Tribal resource water as described in paragraph (g)(4).

(ii) The tribe shall issue a public notice regarding the decision to assign a water as an

outstanding Tribal resource water. The Tribe will maintain a comprehensive list of the

reservation waters that have been assigned as an outstanding Tribal resource waters

consistent with paragraph (f)(3).

(iii) The Tribe may allow short-term, temporary water quality degradation in an

outstanding Tribal resource water only if the short-term, temporary degradation is limited

to the shortest possible time, does not impact existing uses, and does not alter the

essential or special characteristics that make the reservation water an outstanding Tribal

resource water. Short-term shall be considered any period that is measured in the context

of weeks to months, not years.

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(h) Wetlands designated uses, narrative and numeric water quality criteria, and antidegradation

requirements:

(1) Definition: Wetlands within the WRPT Reservation were classified utilizing the Cowardin

classification system. There are 10,223.1 acres of wetlands classified according to the USFWS

National Wetlands Inventory (NWI) database defined as freshwater emergent, freshwater

forested, freshwater scrub shrub, freshwater ponds, including lakes and reservoirs. Freshwater

Emergent Wetlands include 1,460.2 acres. Freshwater Forested and Scrub/Shrub Wetlands

include 1,239.79 acres. Freshwater Ponds include 522.48 acres. Lakes-Reservoirs include

2,690.35 acres.

(2) Designated Uses. For waters designated in paragraph (a) that constitute wetlands, as

defined by the Cowardin classification scheme, the designated uses are: base flow discharge,

cultural and traditional uses, flood flow attenuation, groundwater recharge, indigenous floral

and faunal diversity and abundance, nutrient cycling, organic carbon export/cycling, protection

of downstream water quality, recreation, resilience against climatic effects, sediment/shoreline

stabilization, surface water storage, and water-dependent wildlife. 1

(3) Narrative criteria. All waters included in paragraph (a) that constitute wetlands, as defined

by the Cowardin classification scheme, shall maintain the biological, physical, and chemical

conditions of reference wetlands 2, specifically: base flow, flow regime, wetland hydroperiod;

chemical, nutrient, dissolved oxygen regime of the wetland; conditions favorable to protection

and propagation of threatened, endangered, and at-risk species; conductivity; floristic quality;

integrity of species diversity, abundance, zonation; normal movement of fauna; pH of wetland

waters; salinity; size and shape of the wetland; soil type horizon structure; water currents;

erosion and sedimentation patterns; water levels or elevations; and water temperature

variations.

(4) Numeric criteria. For all waters included in paragraph (a) that constitute wetlands, numeric

criteria identified in Table 1, 1a, 1b, Table 2, Table 3, Table 4, and the “Organism Only”

column of Table 5, apply.

(5) Recreational water quality criteria. For all waters included in paragraph (a) that constitute

wetlands, numeric criteria identified in Table 6 shall apply.

Additionally, the concentration of total microcystins shall not exceed 8 µg/L in more than

three ten-day periods per recreational season, for more than one recreational season, over a

five-year period and the concentration of total cylindrospermopsin shall not exceed 15 µg/L

in more than three ten-day periods per recreational season, for more than one recreational

season, over a five-year period.

These wetlands-specific designated uses represent the uses specified in 101(a)(2) of the Clean Water Act.

Note: A “reference wetland” is a specific locality on a water body which is unimpaired or minimally impaired and

is representative of the expected biological integrity of other localities on the same water body or nearby water

bodies.

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(6) Antidegradation requirements. For waters designated in paragraph (a) that constitute

wetlands, as defined by the Cowardin classification scheme, the following antidegradation

requirements shall apply:

(i) Maintenance and protection of existing instream water uses and the level of water

quality necessary to protect the existing uses consistent with paragraphs (f) and (g);

(ii) No net loss to the water quality, functions, values, area, or ecological integrity of high

quality wetlands, unless, after satisfying applicable antidegradation provisions including

avoidance, minimization, and mitigation/replacement requirements, the WRPT determines

that allowing degradation is necessary to accommodate important social or economic

development in the area in which the wetlands are located consistent with paragraphs (f)

and (g); and

(iii) No loss to the water quality, functions, values, area, or ecological integrity of wetlands

assigned as Outstanding National Resource Waters consistent with paragraphs (f) and (g).

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(i) Mixing Zone Policy (Reserved)

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(j) Compliance schedule authorizing provision

The WRPT authorizes the use of compliance schedules, on a case-by-case basis, for water

quality-based effluent limits in National Pollutant Discharge Elimination System (NPDES)

permits, when appropriate, and consistent with 40 CFR 122.47, for new, recommencing, or

existing dischargers to require compliance as soon as possible with water quality-based

effluent limitations calculated to meet water quality standards issued or revised after July 1,

1977.

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(k) WQS variance authorizing provision

The WRPT may consider issuing WQS variances per this section. Any WQS variances adopted

subsequent to the adoption of this section must be consistent with the regulation at 40 CFR

131.14. A WQS variance is not effective for CWA purposes and thus cannot be implemented

for purposes of NPDES permitting or CWA section 401 certification until EPA has approved

it under CWA section 303(c).

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(l) Water Body-Specific designated uses, criteria, and WQS variances

Paragraph l will catalog any variances adopted in the future and is intentionally left blank until

such time as it is needed.

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(m) Tables

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Table 1. Aquatic Life Criteria

Aquatic Life Criteria

Freshwater

Criterion Continuous

Concentration (CCC)

(µg/L)

Compound

CAS Number

Criterion Maximum

Concentration (CMC)

(µg/L)

Acrolein

107028

Aldrina

309002

1.5

20000

Alkalinityb

alpha-Endosulfan

959988

Aluminum pH 5.0 – 10.5

7429905

Ammonia

7664417

a,c

0.11

0.056

Acute (CMC) and chronic (CCC) freshwater aluminum

criteria values for a site shall be calculated using the

2018 Aluminum Criteria Calculator (Aluminum Criteria

Calculator V.2.0.xlsx, or a calculator in R or other

software package using the same 1985 Guidelines

calculation approach and underlying model equations as

in the Aluminum Criteria Calculator V.2.0.xlsx) as

established in EPA’s Final Aquatic Life Ambient Water

Quality Criteria for Aluminum 2018 (EPA 822–R–18–

001). Where required by federal regulations,

measurements of total recoverable aluminum shall be

used. To apply the aluminum criteria for Clean Water

Act purposes, criteria values based on ambient water

chemistry conditions must protect the water body over

the full range of variability, including during conditions

when aluminum is most toxic.

See Table 4

7440382

340

150

beta-Endosulfan

33213659

0.11

0.056

Cadmiume

7440439

See Table 1b

Carbaryl

63252

2.1

57749

1.2

0.0043

Chloride

16887006

860000

230000

Chlorine

7782505

0.041

Arsenicd,e

a,c

Chlordane

2921882

0.083

16065831

See Table 1b

Chromium (VI)e

18540299

Coppere

7440508

See Table 2

57125

5.2

8065483

0.1

Chlorpyrifos

Chromium (III)

Cyanide

Demeton

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Aquatic Life Criteria

Freshwater

Criterion Continuous

Concentration (CCC)

(µg/L)

Compound

CAS Number

Criterion Maximum

Concentration (CMC)

(µg/L)

Diazinon

333415

0.17

Dieldrin

60571

0.24

0.056

Endrin

72208

0.086

0.036h

gamma-BHC (Lindane)

58899

0.95

Guthion

86500

0.01

76448

0.26

0.0038

Heptachlor

1024573

0.26

0.0038

7439896

1000

Lead

Malathion

7439921

121755

See Table 1b

0.1

Mercurye,j

7439976

Reserved

Methoxychlor

72435

0.03

Mirex

0.001

Heptachlor Epoxide

a,i

Iron

2385855

Nickel

7440020

See Table 1b

Nonylphenol

84852153

Oxygen, Dissolvedk

7782447

June-October ≥5.0 mg/l; November-May ≥6.0 mg/l

Parathion

56382

0.065

87865

Pentachlorophenol

pHm

Polychlorinated Biphenyls

(PCBs)

Seleniume

6.6

0.013

15l

6.5 – 9

0.014

7782492

See Table 3

7440224

See Table 1b

Sulfide-Hydrogen Sulfide

7783064

Toxaphene

8001352

0.73

0.0002

0.46

0.072

Silver

a,e,o

Tributyltin (TBT)

Zinc

4,4'-DDT

7440666

See Table 1b

50293

0.55

0.001

Notes to Table 1

1. The CMC is the highest allowable one-hour average instream concentration of a pollutant and is not to be

exceeded more than once every three years. Except where noted otherwise, the CCC is the highest allowable fourday average instream concentration of a pollutant and is not to be exceeded more than once every three years.

2. Because of variations in chemical nomenclature systems, this listing of toxic pollutants does not duplicate

the listing in Appendix A to 40 CFR Part 423 - 126 Priority Pollutants. The Chemical Abstracts Services (CAS)

registry numbers provide a unique identification for each chemical.

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Footnotes to Table 1:

a. These criteria are based on the 1980 criteria, which used different Minimum Data Requirements and

derivation procedures from the 1985 Guidelines. The CMC derived using the 1980 Guidelines was derived

to be used as an instantaneous maximum. Therefore, in order to treat these in a similar manner to more recent

criteria developed using the 1985 Guidelines, the CMC values given are the result of dividing by 2 to obtain

a value that is more comparable to a CMC derived using the 1985 Guidelines.

b. The CCC of 20mg/L is a minimum value except where alkalinity is naturally lower, in which case the

alkalinity cannot be lower than 25% of the natural level.

c. This value was derived from data for endosulfan and is most appropriately applied to the sum of alphaendosulfan and beta-endosulfan.

d. This recommended water quality criterion was derived from data for arsenic (III), but is applied here to total

arsenic.

e. Freshwater criteria for these metals are expressed in terms of the dissolved metal in the water column. See

Office of Water Policy and Technical Guidance on Interpretation and Implementation of Aquatic Life Metals

Criteria. See Table 1a for conversion factors to convert between total recoverable and dissolved

measurements.

g. These recommended water quality criteria are expressed as µg free cyanide per liter.

h. The derivation of the CCC for this pollutant did not consider exposure through the diet, which is probably

important for aquatic life occupying upper trophic levels.

i. This value was derived from data for heptachlor and there was insufficient data to determine relative toxicities

of heptachlor and heptachlor epoxide.

k. For fresh waters, see Quality Criteria for Water, 1986 ("Gold Book"). The duration and the frequency

designated for impairment is one that protects the highest designated use for aquatic life for the protection of

aquatic life in freshwaters (mg/L of DO) for the 30-day mean. Also see the EPA DO Fact sheet.

https://www.epa.gov/system/files/documents/2021-07/parameter-factsheet_do.pdf

l. Freshwater aquatic life values for pentachlorophenol are expressed as a function of pH and values displayed

in table correspond to a pH of 7.8. CCC = e 1.005(pH) – 5.134, CMC = e 1.005 (pH) – 4.869

m. Reserved

o. The result of the equation given in Table 1b for silver must be divided by 2 to obtain a value that is more

comparable to a CMC derived using the 1985 Guidelines.

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Table 1a: Conversion Factors for Dissolved Metals Criteria

Metal

Arsenic

Cadmium

Chromium

III

Chromium

Copper

Lead

Mercury

Nickel

Selenium

Silver

Zinc

Freshwater CMC

1.000

1.136672-[(ln

hardness)(0.041838)]

0.316

Freshwater CCC

1.000

1.101672-[(ln

hardness)(0.041838)]

0.860

0.982

0.962

0.960

1.46203-[(ln

hardness)(0.145712)]

0.85

0.998

—

0.85

0.978

0.960

1.46203-[(ln

hardness)(0.145712)]

—

0.997

—

0.986

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Table 1b: Parameters for Calculating Freshwater Dissolved Metals Criteria That Are

Hardness-Dependent

Chemical

Cadmium

0.978

0.819

1.273

3.866

3.725

1.460

2.255

0.740

0.819

1.273

-4.719

0.846

—

0.847

Chromium

III

Lead

Nickel

Silver

Zinc

0.846

1.72

0.847

-6.59

0.884

0.6848

Freshwater Conversion Factors (CF)

CMC

CCC

1.1366721.101672-[(lnhardness)(0.041838)]

[(lnhardness)(0.041838)]

0.316

0.860

-4.705

1.46203-[(lnhardness)(0.145712)]

0.0584

0.998

0.997

—

0.884

0.85

0.978

—

0.986

Hardness-dependent metals criteria are calculated using the following equations:

CMC (dissolved) = exp{mA [ln(hardness)]+ bA} (CF)

CCC (dissolved) = exp{mC [ln(hardness)]+ bC} (CF)

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Table 2. Copper Aquatic Life Criteria for Fresh Waters

Metal

CAS No.

Copper

7440508

Criterion

Maximum Criterion

Continuous

Concentration

(CMC)

Concentration

(CCC)

(µg/L)

Acute (CMC) and chronic (CCC) freshwater copper criteria shall

be developed using EPA’s 2007 Aquatic Life Ambient Freshwater

Quality Criteria—Copper (EPA–822–R–07–001), which

incorporates use of the copper biotic ligand model (BLM). Where

sufficiently representative ambient data for DOC, calcium,

magnesium, sodium, potassium, sulfate, chloride, or alkalinity are

not available, the WRPT shall use the 10th percentile values from

publicly available peer-reviewed datasets such as the US

Geological Survey National Waters Information System (NWIS)

and EPA’s Storage and Retrieval Data Warehouse.

The CMC is the highest allowable one-hour average instream concentration of copper. The CMC is not to be exceeded

more than once every three years.

The CCC is the highest allowable four-day average instream concentration of copper. The CCC is not to be exceeded

more than once every three years.

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Table 3. Selenium Aquatic Life Criteria for Fresh Waters

Criterion Element

Fish Tissuea (Egg-Ovary)b

Magnitude

15.1 mg/kg dw

Fish Tissuea

(Whole Body or Muscle)d

8.5 mg/kg dw

11.3 mg/kg dw muscle

(skinless, boneless filet)

1.5 µg/L in lentic aquatic

systems

Water Columne

(Monthly Average Exposure)

Duration

Instantaneous

measurementc

Instantaneous

measurementc

Frequency

Not to be exceeded

30 days

Not more than once

in three years on

average

Not to be exceeded

3.1 µg/L in lotic aquatic

systems

Water Columne

WQCint =

Number of days/month Not more than once

(Intermittent Exposure)f

WQC30-day – Cbkgrnd(1 – fint)

with

elevated in three years on

fint

concentration

average

Fish tissue elements are expressed as steady-state.

Egg/ovary supersedes any whole-body, muscle, or water column element when fish egg/ovary concentrations are

measured, except as noted in footnote d below.

Fish whole-body or muscle tissue supersedes water column element when both fish tissue and water concentrations

are measured, except as noted in footnote d below.

Water column values are based on dissolved total selenium in water and are derived from fish tissue values via

bioaccumulation modeling. When selenium inputs are increasing, water column values are the applicable criterion

element in the absence of steady-state condition fish tissue data.

Where WQC30-day is the water column monthly element for either lentic or lotic waters; Cbkgrnd is the average

background selenium concentration; and fint is the fraction of any 30-day period during which elevated selenium

concentrations occur, with fint assigned a value ≥0.033 (corresponding to 1 day).

Fish tissue data provide instantaneous point measurements that reflect integrative accumulation of selenium over

time and space in fish population(s) at a given site.

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Table 4. Ammonia Aquatic Life Criteria for Fresh Waters

mg Total Ammonia Nitrogen (TAN)/L

Acute (CMC) equation

(1 hour average)

Chronic (CCC) equation

(30-day rolling average)*

Note: Ammonia criteria are a function of pH and temperature. At the standard normalized pH of 7.0 and

temperature of 20 oC, the acute criterion would be 17 mg TAN/L and the chronic criterion would be 1.9 mg TAN/L.

Criteria duration: the acute criterion is a one-hour average and the chronic criterion is a thirty-day rolling average.

Criteria frequency: Not to be exceeded more than once in 3 years.

* Not to exceed 2.5 times the CCC as a 4-day average within the 30-days, i.e. 4.8 mg TAN/L at pH 7 and 20 oC.

more than once in 3 years on average.

Note to Table 4: Acute (CMC) and chronic (CCC) freshwater ammonia criteria were developed using EPA’s 2013

Aquatic Life Ambient Water Quality Criteria for Ammonia - Freshwater (EPA–822–R–13–001), which is hereby

incorporated by reference. Illustrations, tables, and formulae used in the development of these equations can be found

on pages 40-52 of the criteria document. Alternative equations for the presence or absence of Oncorhynchus sp.

(rainbow trout) can be found on pages 41-42 of the document.

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Table 5. Human Health Criteria

Calculated Human Health Criteria based on a Fish Consumption Rate of 22

grams/day

and Cancer Risk Level of 1 in 1,000,000 people (10-6)

Pollutant

CAS

Number

Water +

Organism

(µg/L)

Organism

Only

(µg/L)

1,1,1-Trichloroethane a

71556

10000

200000

1,1,2,2-Tetrachloroethane

79345

0.2

1,1,2-Trichloroethane a

79005

0.55

8.6

1,1-Dichloroethylene a

75354

300

20000

1,2,4,5-Tetrachlorobenzene

95943

0.03

1,2,4-Trichlorobenzene a

120821

0.069

0.073

1,2-Dichlorobenzene a

95501

1000

3000

1,2-Dichloroethane a

107062

9.9

630

1,2-Dichloropropane

78875

0.9

1,2-Diphenylhydrazine

122667

0.03

0.2

1,2-Trans-Dichloroethylene a

156605

100

4000

1,3-Dichlorobenzene

541731

1,3-Dichloropropene

542756

0.27

1,4-Dichlorobenzene a

106467

300

900

2,4,5-Trichlorophenol b

95954

300

600

2,4,6-Trichlorophenol b

88062

1.4

2.7

2,4-Dichlorophenol b

120832

2,4-Dimethylphenol b

105679

100

2000

2,4-Dinitrophenol

51285

300

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Calculated Human Health Criteria based on a Fish Consumption Rate of 22

grams/day

and Cancer Risk Level of 1 in 1,000,000 people (10-6)

Pollutant

CAS

Number

Water +

Organism

(µg/L)

Organism

Only

(µg/L)

2,4-Dinitrotoluene

121142

0.048

1.6

2-Chloronaphthalene

91587

800

1000

2-Chlorophenol b

95578

800

2-Methyl-4,6-Dinitrophenol

534521

3,3'-Dichlorobenzidine

91941

0.049

0.14

3-Methyl-4-Chlorophenol b

59507

500

2000

4,4'-DDD

72548

0.00012

4,4'-DDE

72559

0.000017

4,4'-DDT

50293

0.00003

Acenaphthene b

83329

Acrolein

107028

400

Acrylonitrile

107131

0.061

6.7

Aldrin

309002

7.4e-7

alpha-BHC

319846

0.00035

0.00038

alpha-Endosulfan

959988

Anthracene

120127

300

400

Antimony a,c,d

7440360

5.3

580

Arsenic c, j

7440382

0.014

0.047

Asbestos a,c,e

1332214

7 million

fibers/L

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Calculated Human Health Criteria based on a Fish Consumption Rate of 22

grams/day

and Cancer Risk Level of 1 in 1,000,000 people (10-6)

Pollutant

CAS

Number

Water +

Organism

(µg/L)

Organism

Only

(µg/L)

Barium a,c,e,f

7440393

1000

Benzene a

71432

0.58

Benzidine

92875

0.00014

0.01

Benzo(a) Anthracene

56553

0.0012

0.0013

Benzo(a) Pyrene a

50328

0.00012

0.00013

Benzo(b) Fluoranthene

205992

0.0012

0.0013

Benzo(k) Fluoranthene

207089

0.012

0.013

beta-BHC (beta-HCH)

319857

0.0079

0.014

beta-Endosulfan

33213659

Bis(2-Chloro-1-Methylethyl) Ether

108601

200

3000

Bis(2-Chloroethyl) Ether

111444

0.03

2.1

Bis(2-Ethylhexyl) Phthalate a

117817

0.32

0.37

Bis(Chlormethyl) Ether

542881

0.00015

0.017

Bromoform a

75252

110

Butylbenzyl Phthalate

85687

0.1

Carbon Tetrachloride a

56235

0.4

Chlordane a

57749

0.0003

0.00031

Chlorobenzene a,b

108907

100

800

Chlorodibromomethane a

124481

0.8

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Calculated Human Health Criteria based on a Fish Consumption Rate of 22

grams/day

and Cancer Risk Level of 1 in 1,000,000 people (10-6)

Pollutant

CAS

Number

Water +

Organism

(µg/L)

Organism

Only

(µg/L)

Chloroform a

67663

2000

Chlorophenoxy Herbicide (2,4,5-TP)

[Silvex] a

93721

100

400

Chlorophenoxy Herbicide (2,4-D) a

94757

1300

12000

Chrysene a

218019

0.12

0.13

Copper a,b,c,e

7440508

1300

Cyanide a

57125

400

Di-n-Butyl Phthalate

84742

Dibenzo(a,h) Anthracene

53703

0.00012

0.00013

Dichlorobromomethane a

75274

0.94

Dieldrin

60571

0.0000012

Diethyl Phthalate

84662

600

Dimethyl Phthalate

131113

2000

Dinitrophenols

25550587

1000

Dioxin c

1746016

4.6e-9

4.7e-9

Endosulfan Sulfate

1031078

Endrin

72208

0.03

Endrin Aldehyde a

7421934

Ethylbenzene a

100414

120

Fluoranthene

206440

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Calculated Human Health Criteria based on a Fish Consumption Rate of 22

grams/day

and Cancer Risk Level of 1 in 1,000,000 people (10-6)

Pollutant

CAS

Number

Water +

Organism

(µg/L)

Organism

Only

(µg/L)

Fluorene

86737

Gamma-BHC (HCH); Lindane a

58899

4.1

4.3

Heptachlor a

76448

0.0000057

Heptachlor Epoxide a

1024573

0.000031

Hexachlorobenzene a

118741

0.000076

0.000077

Hexachlorobutadiene a

87683

0.009

Hexachlorocyclohexane (HCH) Technical

608731

0.0064

0.0098

Hexachlorocyclopentadiene a,b

77474

Hexachloroethane

67721

0.1

Indeno(1,2,3-cd) Pyrene

193395

0.0012

0.0013

Isophorone

78591

1800

Manganese b,c,e,g

7439965

100

Methoxychlor a

72435

0.02

Methyl Bromide

74839

100

10000

Methylene Chloride a

75092

1000

Methylmercury c,h

22967926

N/A

0.3 mg/kg

N-Nitrosodi-n-Propylamine c

621647

0.0047

0.46

N-Nitrosodimethylamine c

62759

0.00065

2.7

N-Nitrosodiphenylamine c

86306

5.5

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Calculated Human Health Criteria based on a Fish Consumption Rate of 22

grams/day

and Cancer Risk Level of 1 in 1,000,000 people (10-6)

Pollutant

CAS

Number

Water +

Organism

(µg/L)

Organism

Only

(µg/L)

Nickel c,d

7440020

310

Nitrates a,c,e

14797558

10000

Nitrobenzene b

98953

500

Nitrosamines c

0.000766

0.418

Nitrosodibutylamine c

924163

0.006

0.2

Nitrosodiethylamine c

55185

0.000766

0.418

Nitrosopyrrolidine c

930552

0.016

Pentachlorobenzene

608935

0.1

Pentachlorophenol (PCP) a,b

87865

0.02

0.04

pH c,e

5-9

Phenol b

108952

4000

300000

Polychlorinated Biphenyls (PCBs) a,c,i

1336363

0.000058

Pyrene

129000

Selenium a,c

7782492

760

Solids Dissolved and Salinity c,e

250000

Tetrachloroethylene a

127184

Thallium c

7440280

0.22

0.43

Toluene a

108883

500

Toxaphene a

8001352

0.00068

0.00069

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Calculated Human Health Criteria based on a Fish Consumption Rate of 22

grams/day

and Cancer Risk Level of 1 in 1,000,000 people (10-6)

Pollutant

CAS

Number

Water +

Organism

(µg/L)

Organism

Only

(µg/L)

Trichloroethylene a

79016

0.6

Vinyl Chloride a

75014

0.022

1.6

Zinc b,c

7440666

1400

4600

Footnotes:

a. EPA has issued a Maximum Contaminant Level (MCL) for this chemical which may be more

stringent. Refer to EPA's National Primary Drinking Water Regulations.

b. The criterion for organoleptic (taste and odor) effects may be more stringent. Refer to National

Recommended Water Quality Criteria - Organoleptic Effects.

c. EPA did not update its National Recommended Human Health Water Quality Criteria for this

pollutant in 2015. This table's criteria values are calculated using the 2015 revised inputs for body

weight, drinking water intake rate, and a fish consumption rate of 22 g/day (refer to 2015 EPA

Updated Ambient Water Quality Criteria for the Protection of Human Health). The criteria values

in this table therefore may not match the values in (cite to EPA's 304a) which are based on pre2015 inputs.

d. This criterion was revised to reflect EPA's q1* or RfD as contained in the Integrated Risk

Information System (IRIS) as of May 17, 2002. The fish tissue bioconcentration factor (BCF) is

from the 1980 Ambient Water Quality Criteria document.

e. Criteria for these pollutants are from the National Recommended Water Quality Criteria - Human

Health Criteria Table. They are not calculated based on this table's inputs for fish consumption

rate and cancer risk level.

f. This human health criterion is the same as originally published in the Quality Criteria for Water,

1976 ("Red Book") which predates the 1980 methodology and did not utilize the fish ingestion

BCF approach. This same criterion value is published in the Quality Criteria for Water, 1986

("Gold Book").

g. The Human Health for the consumption of Water + Organism criterion for manganese is not

based on toxic effects, but rather is intended to minimize objectionable qualities such as laundry

stains and objectionable tastes in beverages.

h. This fish tissue residue criterion for methylmercury is based on the total fish consumption rate.

i. This criterion applies to total PCBs (e.g., the sum of all congener or all isomer or homolog or

Aroclor analyses).

j. This criterion for arsenic refers to the inorganic form only.

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Table 6. Recreational Water Quality Criteria

Estimated Illiness Rate:

36 per 1,000 primary contact recreators

Magnitude

GM (cfu/100 mL)a

STV (cfu/100 mL)

126

410

Criteria Elements

Indicator

coli

(fresh water)

EPA Method 1600, or another equivalent method, shall be used to

measure culturable enterococci. EPA Method 1603 (U.S. EPA, 2002b),

or another equivalent method, shall be used to measure E. coli.

Duration and Frequency: The water body GM should not be greater

than the selected GM magnitude in any 30-day interval. There should

not be greater than a ten percent excursion frequency of the selected

STV magnitude in the same 30-day interval.

Table 6. Design Flows

Criteria

Aquatic Life Acute Criteria (CMC)

Aquatic Life Chronic Criteria (CCC)

Human Health Criteria

Design Flow

1 Q 10 or 1 B 3

7 Q 10 or 4 B 3

Harmonic Mean Flow

Notes to Table 7:

1. CMC (Criteria Maximum Concentration) is the water quality criterion to protect against acute effects in

aquatic life and is the highest instream concentration of a priority pollutant consisting of a short

term- average not to be exceeded more than once every three years on the average;

2. CCC (Continuous Criteria Concentration) is the water quality criterion to protect against chronic effects in

aquatic life and is the highest in stream concentration of a priority pollutant consisting of a 4-day average

not to be exceeded more than once every three years on the average;

3. 1 Q 10 is the lowest one-day flow with an average recurrence frequency of once in 10 years determined

hydrologically;

4. 1 B 3 is biologically based and indicates an allowable exceedance of once every 3 years. It is determined

by EPA's computerized method (DFLOW model);

5. 7 Q 10 is the lowest average 7 consecutive day low flow with an average recurrence frequency of once in

10 years determined hydrologically;

6. 4 B 3 is biologically based and indicates an allowable exceedance for 4 consecutive days once every 3

years. It is determined by EPA's computerized method (DFLOW model).

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This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.