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Water: Current Water Quality Criteria

National Recommended Water Quality Criteria

EPA's compilation of national recommended water quality criteria is presented as a summary table containing recommended water quality criteria for the protection of aquatic life and human health in surface water for approximately 150 pollutants. These criteria are published pursuant to Section 304(a) of the Clean Water Act (CWA) and provide guidance for states and tribes to use in adopting water quality standards.

Aquatic Life Criteria Table

      Freshwater Saltwater  
Pollutant CAS Number P/NP* CMC 1 
CCC 1 
CMC 1 
CCC 1 
Publication Year
Acrolein 107028 P 3ug/L 3ug/L     2009
Aldrin 309002 P 3.0 G   1.3 G   1980
Alkalinity NP   20000 C     1986
alpha-Endosulfan 959988 P 0.22 G, Y 0.056 G, Y 0.034 G, Y 0.0087 G, Y 1980
Aluminum pH 6.5 – 9.0 7429905 NP 750 I 87 I, S     1988
Ammonia 7664417 NP FRESHWATER CRITERIA ARE pH, Temperature and Life-stage DEPENDENT

Arsenic 7440382 P 340 A, D 150 A, D 69 A, D 36 A, D 1995
beta-Endosulfan 33213659 P 0.22 G, Y 0.056 G, Y 0.034 G, Y 0.0087 G, Y 1980
Carbaryl 63252 NP 2.1 2.1 1.6 2012
Cadmium 7440439 P 2.0 D, E 0.25 D, E 40 D 8.8 D 2001
Chlordane 57749 P 2.4 G 0.0043 G 0.09 G 0.004 G 1980
Chloride 16887006 NP 860000 230000     1986
Chlorine 7782505 NP 19 11 13 7.5 1986
Chloropyrifos 2921882 NP 0.083 0.041 0.011 0.0056 1986
Chromium (III) 16065831 P 570 D, E 74 D, E     1995
Chromium (VI) 18540299 P 16 D 11 D 1,100 D 50 D 1995
Copper 7440508 P Freshwater criteria calculated using the BLM mm - See Document 4.8 D, cc 3.1 D, cc 2007
Cyanide 57125 P 22 Q 5.2 Q 1 Q 1 Q 1985
Demeton 8065483 NP   0.1 C   0.1 C 1985
Diazinon 333415 NP 0.17ug/L 0.17ug/L 0.82ug/L 0.82ug/L 2005
Dieldrin 60571 P 0.24 0.056 O 0.71 G 0.0019 G 1995
Endrin 72208 P 0.086 0.036 O 0.037 G 0.0023 G 1995
gamma-BHC (Lindane) 58899 P 0.95   0.16 G   1995
Guthion 86500 NP   0.01 C   0.01 C 1986
Heptachlor 76448 P 0.52 G 0.0038 G 0.053 G 0.0036 G 1980
Heptachlor Epoxide 1024573 P 0.52 G, V 0.0038 G, V 0.053 G, V 0.0036 G, V 1981
Iron 7439896 NP   1000 C     1986
Lead 7439921 P 65 D, E 2.5 D, E 210 D 8.1 D 1980
Malathion 121755 NP   0.1 C   0.1 C 1986




P 1.4 D, hh


0.77 D, hh


1.8 D, ee, hh


0.94 D, ee, hh


Methoxychlor 72435 NP   0.03 C   0.03 C 1986
Mirex 2385855 NP   0.001 C   0.001 C 1986
Nickel 7440020 P 470 D, E 52 D, E 74 D 8.2 D 1995
Nonylphenol 84852153 NP 28ug/L 6.6ug/L 7ug/L 1.7ug/L 2005
Nutrients NP See EPA's Ecoregional criteria for Total Phosphorus, Total Nitrogen, Chlorophyll a and Water Clarity (Secchi depth for lakes; turbidity for streams and rivers) (& Level III Ecoregional criteria)
Oxygen, Dissolved Freshwater
Oxygen, Dissolved Saltwater
Parathion 56382 NP 0.065 I 0.013 I     1995
Pentachlorophenol 87865 P 19 F 15 F 13 7.9 1995
pH NP   6.5 – 9 C   6.5 – 8.5 C, P 1986
Phosphorus Elemental 7723140 NP         1986
Polychlorinated Biphenyls (PCBs)   P   0.014 N   0.03 N
Selenium 7782492 P L, R 5.0 R 290 D, dd 71 D, dd 1999
Silver 7440224 P 3.2 D, E   1.9 D   1980
Solids Suspended and Turbidity NP NARRATIVE STATEMENT—SEE DOCUMENT C 1986
Sulfide-Hydrogen Sulfide 7783064 NP   2.0 C   2.0 C 1986
Toxaphene 8001352 P 0.73 0.0002 0.21 0.0002 1986
Tributyltin (TBT) NP 0.46 0.072 0.42 0.0074 2004
Zinc 7440666 P 120 D, E 120 D, E 90 D 81 D 1995
4,4'-DDT 50293 P 1.1 G, ii 0.001 G, ii 0.13 G, ii 0.001 G, ii 1980
*P/NP – Indicates either a Priority Pollutant (P) or a Non Priority Pollutant (NP).


A This recommended water quality criterion was derived from data for arsenic (III), but is applied here to total arsenic, which might imply that arsenic (III) and arsenic (V) are equally toxic to aquatic life and that their toxicities are additive.  No data are known to be available concerning whether the toxicities of the forms of arsenic to aquatic organisms are additive.  Please consult the criteria document for details.

C The derivation of this value is presented in the Red Book (EPA 440/9-76-023, July, 1976). The CCC of 20mg/L is a minimum value except where alkalinity is naturally lower, in which case the criterion cannot be lower than 25% of the natural level.

D Freshwater and saltwater criteria for 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 (PDF)," (49 pp, 3MB) October 1, 1993, by Martha G. Prothro, Acting Assistant Administrator for Water, available on NSCEP's web site and 40CFR§131.36(b)(1). Conversion Factors applied in the table can be found in Appendix A to the Preamble- Conversion Factors for Dissolved Metals.

E The freshwater criterion for this metal is expressed as a function of hardness (mg/L) in the water column. The value given here corresponds to a hardness of 100 mg/L. Criteria values for other hardness may be calculated per the equation presented in the criteria document.

F Freshwater aquatic life values for pentachlorophenol are expressed as a function of pH. Values displayed in table correspond to a pH of 7.8.

G This Criterion is based on 304(a) aquatic life criterion issued in 1980, and was issued in one of the following documents: Aldrin/Dieldrin (PDF) (153 pp, 7.3MB) (EPA 440/5-80-019), Chlordane (PDF) (68 pp, 3.1MB) (EPA 440/5-80-027), DDT (PDF) (175 pp, 8.3MB) (EPA 440/5-80-038), Endosulfan (PDF) (155 pp, 7.3MB) (EPA 440/5-80-046), Endrin (PDF) (103 pp, 4.6MB) (EPA 440/5-80-047), Heptachlor (PDF) (114 pp, 5.4MB) (EPA 440/5-80-052), Hexachlorocyclohexane (PDF) (109 pp, 4.8MB) (EPA 440/5-80-054), Silver (EPA 440/5-80-071). The Minimum Data Requirements and derivation procedures were different in the 1980 Guidelines than in the 1985 Guidelines (PDF) (104 pp, 3.3MB).  If evaluation is to be done using an averaging period, the acute criteria values given should be divided by 2 to obtain a value that is more comparable to a CMC derived using the 1985 Guidelines.

I This value for aluminum is expressed in terms of total recoverable metal in the water column.

J This value was derived using the GLI Guidelines (60 FR 15393-15399, March 23, 1995; 40CFR132 Appendix A); the differences between the 1985 Guidelines and the GLI Guidelines are explained on page iv of the 1995 Updates. No decision concerning this criterion was affected by any considerations that are specific to the Great Lakes.

L The CMC = 1/[(f1/CMC1) + (f2/CMC2)] where f1 and f2 are the fractions of total selenium that are treated as selenite and selenate, respectively, and CMC1 and CMC2 are 185.9 ug/l and 12.82 ug/l, respectively.  However, based on findings from a February 2009 SETAC Pellston Workshop on Ecological Assessment of Selenium in the Aquatic Environment, diet is the primary pathway of selenium exposure to aquatic life, and traditional methods for predicting toxicity on the basis of exposure to dissolved concentrations are not appropriate for selenium. (To view a summary of the SETAC Pellston workshop including key findings visit http://www.setac.org/resource/resmgr/publications_and_resources/selsummary.pdf).

M U.S. EPA. 1973. Water Quality Criteria 1972. EPA-R3-73-033. National Technical Information Service, Springfield, VA.; U.S. EPA. 1977. Temperature Criteria for Freshwater Fish: Protocol and Procedures. EPA 600/3-77-061. National Technical Information Service, Springfield, VA.

N This criterion applies to total PCBs, (e.g., the sum of all congener or all isomer or homolog or Aroclor analyses.)

O The derivation of the CCC for this pollutant (Endrin) did not consider exposure through the diet, which is probably important for aquatic life occupying upper trophic levels.

P According to page 181 of the Red Book:

For open ocean waters where the depth is substantially greater than the euphotic zone, the pH should not be changed more than 0.2 units from the naturally occurring variation or any case outside the range of 6.5 to 8.5. For shallow, highly productive coastal and estuarine areas where naturally occurring pH variations approach the lethal limits of some species, changes in pH should be avoided but in any case should not exceed the limits established for fresh water, i.e., 6.5-9.0.

Q This recommended water quality criterion is expressed as ug free cyanide (as CN)/L.

R EPA is in the process of updating this criterion to reflect the latest scientific information. See EPA's Aquatic Life Criterion - Selenium website for more information.

S There are three major reasons why the use of Water-Effect Ratios might be appropriate.

  1. The value of 87 µg/l is based on a toxicity test with the striped bass in water with pH = 6.5–6.6 and hardness <10 mg/L. Data in "Aluminum Water-Effect Ratio for the 3M Plant Effluent Discharge, Middleway, West Virginia" (May 1994) indicate that aluminum is substantially less toxic at higher pH and hardness, but the effects of pH and hardness are not well quantified at this time.
  2. In tests with the brook trout at low pH and hardness, effects increased with increasing concentrations of total aluminum even though the concentration of dissolved aluminum was constant, indicating that total recoverable is a more appropriate measurement than dissolved, at least when particulate aluminum is primarily aluminum hydroxide particles. In surface waters, however, the total recoverable procedure might measure aluminum associated with clay particles, which might be less toxic than aluminum associated with aluminum hydroxide.
  3. EPA is aware of field data indicating that many high quality waters in the U.S. contain more than 87 g aluminum/L, when either total recoverable or dissolved is measured.

V This value was derived from data for heptachlor and the criteria document provides insufficient data to estimate the relative toxicities of heptachlor and heptachlor epoxide.

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

cc When the concentration of dissolved organic carbon is elevated, copper is substantially less toxic and use of Water-Effect Ratios might be appropriate.

dd The selenium criteria document (EPA 440/5-87-006, September 1987) provides that if selenium is as toxic to saltwater fishes in the field as it is to freshwater fishes in the field, the status of the fish community should be monitored whenever the concentration of selenium exceeds 5.0 µg/L in salt water because the saltwater CCC does not take into account uptake via the food chain.

ee This recommended water quality criterion was derived on page 43 of the mercury criteria document (PDF) (144 pp, 6.4MB) (EPA 440/5-84-026, January 1985). The saltwater CCC of 0.025 ug/L given on page 23 of the criteria document is based on the Final Residue Value procedure in the 1985 Guidelines. Since the publication of the Great Lakes Aquatic Life Criteria Guidelines in 1995 (60 FR 15393-15399, March 23, 1995), the Agency no longer uses the Final Residue Value procedure for deriving CCCs for new or revised 304(a) aquatic life criteria.

hh This recommended water quality criterion was derived from data for inorganic mercury (II), but is applied here to total mercury. If a substantial portion of the mercury in the water column is methylmercury, this criterion will probably be under protective. In addition, even though inorganic mercury is converted to methylmercury and methylmercury bioaccumulates to a great extent, this criterion does not account for uptake via the food chain because sufficient data were not available when the criterion was derived.

ii This criterion applies to DDT and its metabolites (i.e., the total concentration of DDT and its metabolites should not exceed this value).

mm The available toxicity data, when evaluated using the procedures described in the “Guidelines for Deriving Numerical National Water Quality Criteria for the Protection of Aquatic Organisms and Their Uses” indicate that freshwater aquatic life should be protected if the 24-hour average and four-day average concentrations do not respectively exceed the acute and chronic criteria concentrations calculated by the Biotic Ligand Model.

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Human Health Criteria Table

new icon Final 2015 Updated National Recommended Human Health Criteria

      Human Health for the consumption of  
Pollutant CAS Number P/NP* Water + Organism
Organism Only
Publication Year
Acenaphthene 83329 P 70 A 90 A 2015
Acrolein 107028 P 3 400 2015
Acrylonitrile 107131 P 0.061 C 7.0 C 2015
Aldrin 309002 P 0.00000077
0.00000077 C 2015
alpha-Hexachlorocyclohexane (HCH) 319846 P 0.00036 C 0.00039 C 2015
alpha-Endosulfan 959988 P 20  30  2015
Anthracene 120127 P 300  400  2015
Antimony 7440360 P 5.6 B, D 640 B, D 2002
Arsenic 7440382 P 0.018 C, D, E 0.14 C, D, E 1992
Asbestos 1332214 P 7 million fibers/L D, F   1991
Barium 7440393 NP 1,000 D, G   1986
Benzene 71432 P 0.58-2.1 C, D  16-58 C, D 2015
Benzidine 92875 P 0.00014 C 0.011 C 2015
Benzo(a)anthracene 56553 P 0.0012 C 0.0013 C 2015
Benzo(a)pyrene 50328 P 0.00012 C, D 0.00013 C, D 2015
Benzo(b)fluoranthene 205992 P 0.0012 C
0.0013 C
Benzo(k)fluoranthene 207089 P 0.012 C
0.013 C
Beryllium 7440417 P D  
beta-Hexachlorocyclohexane (HCH) 319857 P 0.0080 C 0.014 C 2015
beta-Endosulfan 33213659 P 20  40  2015
Bis(2-Chloro-1-methylethyl) Ether 108601 P 200  4,000  2015
Bis(2-Chloroethyl) Ether 111444 P 0.030 C 2.2 C 2015
Bis(2-Ethylhexyl) Phthalate 117817 P 0.32 C, D 0.37 C, D 2015
Bis(Chloromethyl) Ether
542881 NP 0.00015 C 0.017 C 2015
Bromoform 75252 P 7.0 C, D 120 C, D 2015
Butylbenzyl Phthalate 85687 P 0.10 C 0.10 C 2015
Cadmium 7440439 P D  
Carbon Tetrachloride 56235 P 0.4 C, D C, D 2015
Chlordane 57749 P 0.00031 C, D 0.00032 C, D 2015
Chlorobenzene 108907 P 100 A, D 800 A, D 2015
Chlorodibromomethane 124481 P 0.80 C, D 21 C, D 2015
Chloroform 67663 P 60 D 2,000 D 2015
Chlorophenoxy Herbicide (2,4-D) 94757 NP 1,300 D 12,000 D
Chlorophenoxy Herbicide (2,4,5-TP) [Silvex] 93721 NP 100 D 400 D 2015
Chromium (III) 16065831 P D Total  
Chromium (VI) 18540299 P D Total  
Chrysene 218019 P 0.12 C, D 0.13 C, D 2015
Copper 7440508 P 1,300 A, D 1992 
Cyanide 57125 P 4 D 400 D 2015
Dibenzo(a,h)anthracene 53703 P 0.00012 C
0.00013 C
Dichlorobromomethane 75274 P 0.95 C, D 27 C, D 2015
Dieldrin 60571 P 0.0000012 C 0.0000012 C 2015
Diethyl Phthalate 84662 P 600  600  2015
Dimethyl Phthalate 131113 P 2,000 2,000 2015
Di-n-Butyl Phthalate 84742 P 20 30  2015
Dinitrophenols 25550587 NP 10 1,000 2015
Endosulfan Sulfate 1031078 P 20  40  2015
Endrin 72208 P 0.03 D 0.03 D 2015
Endrin Aldehyde 7421934 P 2015
Ethylbenzene 100414 P 68 D 130 D 2015
Fluoranthene 206440 P 20  20  2015
Fluorene 86737 P 50  70  2015
gamma-Hexachlorocyclohexane (HCH) [Lindane] 58899 P 4.2D 4.4 D 2015
Heptachlor 76448 P 0.0000059 C, D 0.0000059 C, D 2015
Heptachlor Epoxide 1024573 P 0.000032 C, D 0.000032 C, D 2015
Hexachlorobenzene 118741 P 0.000079 C, D 0.000079 C, D 2015
Hexachlorobutadiene 87683 P 0.01 C, D 0.01 C, D 2015
Hexachlorocyclohexane (HCH) -Technical 608731 NP 0.0066 C 0.010 C 2015
Hexachlorocyclopentadiene 77474 P 4 A, D 4 A, D 2015
Hexachloroethane 67721 P 0.1 C 0.1 C 2015
Indeno(1,2,3-cd)pyrene 193395 P 0.0012 C 0.0013 C 2015
Isophorone 78591 P 34 C 1,800 C 2015
Manganese 7439965 NP 50 A, G, H 100 A, G
Methylmercury 22967926 P     0.3 mg/kg I 2001
Methoxychlor 72435 NP 0.02 D 0.02 D 2015
Methyl Bromide 74839 P 100  10,000  2015
Methylene Chloride 75092 P 20 C, D 1,000 C, D 2015
Nickel 7440020 P 610 B 4,600 B 1998
Nitrates 14797558 NP 10,000 D, G   1986
Nitrobenzene 98953 P 10 A 600 A 2015
Nitrosamines NP 0.0008 1.24 1980
Nitrosodibutylamine, N 924163 NP 0.0063 C 0.22 C 2002
Nitrosodiethylamine, N 55185 NP 0.0008 C 1.24 C 2002
Nitrosopyrrolidine, N 930552 NP 0.016 C 34 C 2002
N-Nitrosodimethylamine 62759 P 0.00069 C 3.0 C 2002
N-Nitrosodi-n-Propylamine 621647 P 0.0050 C 0.51 C 2002
N-Nitrosodiphenylamine 86306 P 3.3 C 6.0 C 2002
Pathogen and Pathogen Indicators See EPA's 2012 Recreational Water Quality Criteria 2012
Pentachlorobenzene 608935 NP 0.1  0.1  2015
Pentachlorophenol 87865 P 0.03 A, C, D 0.04 A, C, D 2015
pH NP 5 – 9   1986
Phenol 108952 P 4,000 A 300,000 A 2015
Polychlorinated Biphenyls (PCBs)   P 0.000064 C, D, J 0.000064 C, D, J 2002
Pyrene 129000 P 20  30  2015
Selenium 7782492 P 170 D 4200 D
Solids Dissolved and Salinity NP 250,000 G   1986
Tetrachloroethylene 127184 P 10 C, D 29 C, D 2015
Thallium 7440280 P 0.24 D 0.47 D 2003
Toluene 108883 P 57 D 520 D
Toxaphene 8001352 P 0.00070 C, D 0.00071 C, D 2015
Trichloroethylene 79016 P 0.6 C, D 7 C, D 2015
Vinyl Chloride 75014 P 0.022 C, D 1.6 C, D 2015
Zinc 7440666 P 7,400 A 26,000 A 2002
1,1,1-Trichloroethane 71556 P 10,000 D 200,000 D 2015
1,1,2,2-Tetrachloroethane 79345 P 0.2 C C 2015
1,1,2-Trichloroethane 79005 P 0.55 C, D 8.9 C, D 2015
1,1-Dichloroethylene 75354 P 300 D 20,000 D 2015
1,2,4,5-Tetrachlorobenzene 95943 NP 0.03
1,2,4-Trichlorobenzene 120821 P 0.071 D
0.076 D
1,2-Dichlorobenzene 95501 P 1,000 D 3,000 D 2015
1,2-Dichloroethane 107062 P 9.9 C, D 650 C, D 2015
1,2-Dichloropropane 78875 P 0.90 C, D 31 C, D 2015
1,2-Diphenylhydrazine 122667 P 0.03 C
0.2 C 2015
Trans-1,2-Dichloroethylene 156605 P 100 D 4,000 D
1,3-Dichlorobenzene 541731 P 7 10 2015
1,3-Dichloropropene 542756 P 0.27 C 12 C 2015
1,4-Dichlorobenzene 106467 P 300 D 900 D 2015
2,3,7,8-TCDD (Dioxin) 1746016 P 5.0E-9 C, D 5.1E-9 C, D 2002
2,4,5-Trichlorophenol 95954 NP 300 A 600 A 2015
2,4,6-Trichlorophenol 88062 P 1.5 A, C 2.8 A, C 2015
2,4-Dichlorophenol 120832 P 10 A 60 A 2015
2,4-Dimethylphenol 105679 P 100 A 3,000 A 2015
2,4-Dinitrophenol 51285 P 10  300  2015
2,4-Dinitrotoluene 121142 P 0.049 C 1.7 C 2015
2-Chloronaphthalene 91587 P 800  1,000  2015
2-Chlorophenol 95578 P 30 A 800 A 2015
2-Methyl-4,6-Dinitrophenol 534521 P 2 30 2015
3,3'-Dichlorobenzidine 91941 P 0.049 C 0.15  C 2015
3-Methyl-4-Chlorophenol 59507 P 500 A 2,000 A 2015
p,p′-Dichlorodiphenyldichloroethane (DDD) 72548 P 0.00012 C 0.00012 C 2015
p,p′-Dichlorodiphenyldichloroethylene (DDE) 72559 P 0.000018 C 0.000018 C 2015
p,p′-Dichlorodiphenyltrichloroethane (DDT) 50293 P 0.000030 C 0.000030 C 2015

*P/NP – Indicates either a Priority Pollutant (P) or a Non Priority Pollutant (NP).


A This chemical has a criterion for organoleptic (taste and order) effects. In some cases, the organoleptic criterion may be more stringent.

B 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.

C This criterion is based on carcinogenicity of 10-6 risk.

D EPA has issued a Maximum Contaminant Level (MCL) for this chemical under the Safe Drinking Water Act.  In some cases, the MCL may be more stringent.  For more information see EPA's National Primary Drinking Water Regulations.

E This recommended water quality criterion for arsenic refers to the inorganic form only.

F This criterion for asbestos is the Maximum Contaminant Level (MCL) developed under the Safe Drinking Water Act (SDWA).

G This human health criterion is the same as originally published in the Red Book which predates the 1980 methodology and did not utilize the fish ingestion BCF approach. This same criterion value is published in the Gold Book.

H This 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.

I This fish tissue residue criterion for methylmercury is based on a total fish consumption rate of 0.0175 kg/day.

J This criterion applies to total PCBs (e.g., the sum of all congener or all isomer or homolog or Aroclor analyses).

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Organoleptic Effects (e.g., taste and odor)

Pollutant CAS Number Organoleptic Effect Criteria
FR Cite/
Acenaphthene 83329 20 Gold Book
Color NP Gold Book
Iron 7439896 300 Gold Book
Red Book
Monochlorobenzene 108907 20 Gold Book
Tainting Substance NP Gold Book
3-Chlorophenol 0.1 Gold Book
4-Chlorophenol 106489 0.1 Gold Book
2,3-Dichlorophenol 0.04 Gold Book
2,5-Dichlorophenol 0.5 Gold Book
2,6-Dichlorophenol 0.2 Gold Book
3,4-Dichlorophenol 0.3 Gold Book
2,4,5-Trichlorophenol 95954 1 Gold Book
2,4,6-Trichlorophenol 88062 2 Gold Book
2,3,4,6-Tetrachlorophenol 1 Gold Book
2-Methyl-4-Chlorophenol 1800 Gold Book
3-Methyl-4-Chlorophenol 59507 3000 Gold Book
3-Methyl-6-Chlorophenol 20 Gold Book
2-Chlorophenol 95578 0.1 Gold Book
Copper 7440508 1000 Gold Book
2,4-Dichlorophenol 120832 0.3 Gold Book
2,4-Dimethylphenol 105679 400 Gold Book
Hexachlorocyclopentadiene 77474 1 Gold Book
Manganese 7439965
Nitrobenzene 98953 30 Gold Book
Pentachlorophenol 87865 30 Gold Book
Phenol 108952 300 Gold Book
Zinc 7440666 5000 45 FR79341


1. These criteria are based on organoleptic (taste and odor) effects. Because of variations in chemical nomenclature systems, this listing of pollutants does not duplicate the listing in Appendix A of 40 CFR Part 423. Also listed are the Chemical Abstracts Service (CAS) registry numbers, which provide a unique identification for each chemical.

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Additional Notes

  1. Criteria Maximum Concentration and Criterion Continuous Concentration

    The Criteria Maximum Concentration (CMC) is an estimate of the highest concentration of a material in surface water to which an aquatic community can be exposed briefly without resulting in an unacceptable effect. The Criterion Continuous Concentration (CCC) is an estimate of the highest concentration of a material in surface water to which an aquatic community can be exposed indefinitely without resulting in an unacceptable effect. The CMC and CCC are just two of the six parts of an aquatic life criterion; the other four parts are the acute averaging period, chronic averaging period, acute frequency of allowed exceedence, and chronic frequency of allowed exceedence. Because 304(a) aquatic life criteria are national guidance, they are intended to be protective of the vast majority of the aquatic communities in the United States.

  2. Criteria Recommendations for Priority Pollutants, Non Priority Pollutants and Organoleptic Effects

    This compilation lists all priority toxic pollutants and some non priority toxic pollutants, and both human health effect and organoleptic effect criteria issued pursuant to CWA §304(a). Blank spaces indicate that EPA has no CWA §304(a) criteria recommendations. For a number of non-priority toxic pollutants not listed, CWA §304(a) "water + organism" human health criteria are not available, but EPA has published MCLs under the SDWA that may be used in establishing water quality standards to protect water supply designated uses. Because of variations in chemical nomenclature systems, this listing of toxic pollutants does not duplicate the listing in Appendix A of 40 CFR Part 423. Also listed are the Chemical Abstracts Service CAS registry numbers, which provide a unique identification for each chemical.

  3. Human Health Risk

    The human health criteria for the priority and non priority pollutants are based on carcinogenicity of 10-6 risk. Alternate risk levels may be obtained by moving the decimal point (e.g., for a risk level of 10-5, move the decimal point in the recommended criterion one place to the right).

  4. Water Quality Criteria published pursuant to Section 304(a) or Section 303(c) of the CWA

    Many of the values in the compilation were published in the California Toxics Rule. Although such values were published pursuant to Section 303(c) of the CWA, they represent the Agency's most recent calculation of water quality criteria and are thus the Agency's 304(a) criteria.

  5. Calculation of Dissolved Metals Criteria

    The 304(a) criteria for metals, shown as dissolved metals, are calculated in one of two ways. For freshwater metals criteria that are hardness-dependent, the dissolved metal criteria were calculated using a hardness of 100 mg/l as CaCO3 for illustrative purposes only. Saltwater and freshwater metals' criteria that are not hardness-dependent are calculated by multiplying the total recoverable criteria before rounding by the appropriate conversion factors. The final dissolved metals' criteria in the table are rounded to two significant figures. Information regarding the calculation of hardness dependent conversion factors are included in the footnotes.

  6. Maximum Contaminant Levels

    The compilation includes footnotes for pollutants with Maximum Contaminant Levels (MCLs) more stringent than the recommended water quality criteria in the compilation. MCLs for these pollutants are not included in the compilation, but can be found in the appropriate drinking water regulations (40 CFR 141.11-16 and 141.60-63), or can be accessed through the Safe Drinking Water Hotline (800-426-4791) or online.

  7. Organoleptic Effects

    The compilation contains 304(a) criteria for pollutants with toxicity-based criteria as well as non-toxicity based criteria. The basis for the non-toxicity based criteria are organoleptic effects (e.g., taste and odor) which would make water and edible aquatic life unpalatable but not toxic to humans. The table includes criteria for organoleptic effects for 23 pollutants. Pollutants with organoleptic effect criteria more stringent than the criteria based on toxicity (e.g., included in both the priority and non-priority pollutant tables) are footnoted as such.

  8. Gold Book

    The "Gold Book" is Quality Criteria for Water: 1986. EPA 440/5-86-001.

  9. Correction of Chemical Abstract Services Number

    The Chemical Abstract Services number (CAS) for Bis(2-Chlorisoprpyl) Ether, has been revised in IRIS and in the table. The correct CAS number for this chemical is 108-60-1. The previous CAS number for this pollutant was 39638-32-9.

  10. Contaminants with Blanks

    EPA has not calculated criteria for contaminants with blanks. However, permit authorities should address these contaminants in NPDES permit actions using the States' existing narrative criteria for toxics.

  11. Specific Chemical Calculations

    Selenium—Aquatic Life
    This compilation contains aquatic life criteria for selenium that are the same as those published in the proposed CTR. In the CTR, EPA proposed an acute criterion for selenium based on the criterion proposed for selenium in the Water Quality Guidance for the Great Lakes System (61 FR 58444). The GLI and CTR proposals take into account data showing that selenium's two prevalent oxidation states in water, selenite and selenate, present differing potentials for aquatic toxicity, as well as new data indicating that various forms of selenium are additive. The new approach produces a different selenium acute criterion concentration, or CMC, depending upon the relative proportions of selenite, selenate, and other forms of selenium that are present.
    EPA is currently undertaking a reassessment of selenium, and expects the 304(a) criteria for selenium will be revised based on the final reassessment (63 FR 26186). However, until such time as revised water quality criteria for selenium are published by the Agency, the recommended water quality criteria in this compilation are EPA's current 304(a) criteria.

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Appendix A—Conversion Factors for Dissolved Metals

Metal Conversion Factor
freshwater CMC freshwater CCC saltwater CMC saltwater CCC1
Arsenic 1.000 1.000 1.000 1.000
Cadmium 1.136672-[(ln hardness)(0.041838)] 1.101672-[(ln hardness)(0.041838)] 0.994 0.994
Chromium III 0.316 0.860
Chromium VI 0.982 0.962 0.993 0.993
Copper 0.960 0.960 0.83 0.83
Lead 1.46203-[(ln hardness)(0.145712)] 1.46203-[(ln hardness)(0.145712)] 0.951 0.951
Mercury 0.85 0.85 0.85 0.85
Nickel 0.998 0.997 0.990 0.990
Selenium 0.998 0.998
Silver 0.85 0.85
Zinc 0.978 0.986 0.946 0.946

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Appendix B—Parameters for Calculating Freshwater Dissolved Metals Criteria That Are Hardness-Dependent

Chemical mA bA mC bC Freshwater Conversion Factors (CF)
Cadmium 1.0166 -3.924 0.7409 -4.719 1.136672-[(lnhardness)(0.041838)] 1.101672-[(lnhardness)(0.041838)]
Chromium III 0.8190 3.7256 0.8190 0.6848 0.316 0.860
Copper 0.9422 -1.700 0.8545 -1.702 0.960 0.960
Lead 1.273 -1.460 1.273 -4.705 1.46203-[(lnhardness)(0.145712)] 1.46203-[(lnhardness)(0.145712)]
Nickel 0.8460 2.255 0.8460 0.0584 0.998 0.997
Silver 1.72 -6.59 0.85
Zinc 0.8473 0.884 0.8473 0.884 0.978 0.986

Hardness-dependant metals' criteria may be calculated from the following:

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

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

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The Gold Book

Quality Criteria for Water, 1986 (PDF) (477 pp., 4.6 MB) May 1986

The Red Book

Quality Criteria for Water, 1976 (PDF) (534 pp., 6.2 MB) July 1976

Chemical Specific Criteria Documents from the 1980s

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