1. Surface water classifications. Procedures for the classifications of streams and lakes of the state shall follow this subsection. Classifications of streams and lakes are listed in appendix I and appendix II, respectively.

a. Class I streams. The quality of the waters in this class shall be suitable for the propagation or protection, or both, of resident fish species and other aquatic biota and for swimming, boating, and other water recreation. The quality of the waters shall be suitable for irrigation, stock watering, and wildlife without injurious effects. After treatment consisting of coagulation, settling, filtration, and chlorination, or equivalent treatment processes, the water quality shall meet the bacteriological, physical, and chemical requirements of the department for municipal or domestic use.

b. Class IA streams. The quality of the waters in this class shall be the same as the quality of class I streams, except that where natural conditions exceed class I criteria for municipal and domestic use, the availability of softening or other treatment methods may be considered in determining whether ambient water quality meets the drinking water requirements of the department.

The Sheyenne River from its headwaters to one-tenth mile downstream from Baldhill Dam is not classified for municipal or domestic use.

c. Class II streams. The quality of the waters in this class shall be the same as the quality of class I streams, except that additional treatment may be required to meet the drinking water requirements of the department. Streams in this classification may be intermittent in nature which would make these waters of limited value for beneficial uses such as municipal water, fish life, irrigation, bathing, or swimming.

d. Class III streams. The quality of the waters in this class shall be suitable for agricultural and industrial uses. Streams in this class generally have low average flows with prolonged periods of no flow. During periods of no flow, they are of limited value for recreation and fish and aquatic biota. The quality of these waters must be maintained to protect secondary contact recreation uses (e.g., wading), fish and aquatic biota, and wildlife uses.

e. Wetlands. These water bodies, including isolated ponds, sloughs, and marshes, are to be considered waters of the state and will be protected under section 33.1-16-02.1-08.

f. Lakes and reservoirs. The type of fishery a lake or reservoir may be capable of supporting is based on the lake's or reservoir's geophysical characteristics. The capability of a lake or reservoir to support a fishery may be affected by seasonal or climatic variability or other natural occurrences, which may alter the physical and chemical characteristics of the lake or reservoir.

Class Characteristics

1 Cold water fishery. Waters capable of supporting growth of cold water fish species (e.g., salmonids) and associated aquatic biota. 2 Cool water fishery. Waters capable of supporting natural reproduction and growth of cool water fishes (e.g., northern pike and walleye) and associated aquatic biota. These waters are also capable of supporting the growth and marginal survival of cold water species and associated biota. 3 Warm water fishery. Waters capable of supporting natural reproduction and growth of warm water fishes (e.g., largemouth bass and bluegill) and associated aquatic biota. Some cool water species may also be present. 4 Marginal fishery. Waters capable of supporting a fishery on a short-term or seasonal basis (generally a "put and take" fishery). 5 Not capable of supporting a fishery due to high salinity.

2. Mixing zones. North Dakota mixing zone and dilution policy is contained in appendix III.

3. Numeric standards.

a. Class I streams. The physical and chemical criteria for class I streams are listed in table 1 and table 2. b. Class IA streams. The physical and chemical criteria shall be those for class I streams, with the exceptions for chloride, percent sodium, and sulfate as listed in table 1. c. Site-specific sulfate standard. The physical and chemical criteria for the Sheyenne River from its headwaters to one-tenth of a mile downstream from Baldhill Dam shall be those for class IA streams, with the exception of sulfate as listed in table 1. d. Class II streams. The physical and chemical criteria shall be those for class IA, with the chloride and pH and sulfates as listed in table 1. e. Class III streams. The physical and chemical criteria shall be those for class II, with the exceptions for sulfate as listed in table 1. f. Wetlands, including isolated ponds, class 4 lakes not listed in appendix II, sloughs and marshes. The physical and chemical criteria shall be those for class III streams, with exceptions for temperature, dissolved oxygen as listed in paragraph 6 of subdivision g,

and other conditions not attributable to municipal, industrial, domestic, or agricultural sources.

g. Lakes and reservoirs.

(1) The physical and chemical criteria for class I streams shall apply to all classified lakes or reservoirs listed in appendix II.

(2) In addition, a guideline for use as a goal in any lake or reservoir improvement or maintenance program is a growing season (April through November) average chlorophyll-a concentration of twenty µg/l.

(3) The temperature standard for class I streams does not apply to Nelson Lake in Oliver County. The temperature of any discharge to Nelson Lake shall not have an adverse effect on fish, aquatic biota, recreation, and wildlife.

(4) A numeric temperature standard of not greater than fifty-nine degrees Fahrenheit [15 degrees Celsius] shall be maintained in the hypolimnion of class I lakes and reservoirs during periods of thermal stratification.

(5) The numeric dissolved oxygen standard of five mg/l as a daily minimum does not apply to the hypolimnion of class III and IV lakes and reservoirs during periods of thermal stratification.

(6) The numeric dissolved oxygen standard of five mg/l as a daily minimum and the maximum temperature of eighty-five degrees Fahrenheit [29.44 degrees Celsius] shall not apply to wetlands and class 4 lakes.

(7) Lake Sakakawea must maintain a minimum volume of water of five hundred thousand-acre feet [61,674-hectare meters] that has a temperature of fifty-nine degrees Fahrenheit [15 degrees Celsius] or less and a dissolved oxygen concentration of not less than five mg/l.

History: Effective January 1, 2019; amended effective July 1, 2021; January 1, 2024.

General Authority: NDCC 61-28-04; S.L. 2017, ch. 199, § 1

Law Implemented: NDCC 23.1-11, 61-28; S.L. 2017, ch. 199, § 26

TABLE 1

MAXIMUM LIMITS FOR SUBSTANCES IN

OR CHARACTERISTICS OF CLASSES I, IA, II, AND III STREAMS

CAS1 No.	Substance or Characteristic (a = aquatic life) (b = municipal & domestic drinking water) (c = agricultural, irrigation, industrial) (d = recreation)	Maximum Limit
7429905	Aluminum2 (a)	Acute Standard 750 micrograms per liter (µg/l) Chronic Standard 87 µg/l Where the pH is equal to or greater than 7.0, and the hardness is equal to or greater than 50 mg/l as CaCO3 in the receiving water after mixing, the 87 µg/l chronic total recoverable aluminum criterion will not apply, and aluminum will be regulated based on compliance with the 750 µg/l acute total recoverable aluminum criterion.
7446-41-7	Ammonia (Total as N) (a)	Acute Standard The one-hour average concentration of total ammonia as nitrogen in mg/l does not exceed, more often than once every three years on the average, the numerical value given by the following: $$0.7249 \times \left( \frac{0.0114}{1 + 107.204 - pH} + \frac{1.6181}{1 + 10pH - 7.204} \right) \times MIN(51.93, 23.12 \times 100.036 \times (20 - T))$$ Where Oncorhynchus are absent; or $$MIN \left( \left( \frac{0.275}{1 + 107.204 - pH} + \frac{39.0}{1 + 10pH - 7.204} \right), \left( 0.7249 \times \left( \frac{0.0114}{1 + 107.204 - pH} + \frac{1.6181}{1 + 10pH - 7.204} \right) \times (23.12 \times 100.036 \times (20 - T)) \right) \right)$$ Where Oncorhynchus are present

		Chronic Standard The 30-day rolling average concentration of total ammonia as nitrogen expressed in mg/l is not to exceed, more than once every three years on average, the chronic criteria magnitude calculated using the following formula: $$0.8876 \times \left( \frac{0.0278}{1 + 107.688 - pH} + \frac{1.1994}{1 + 10pH - 7.688} \right) \times \left( 2.126 \times 100.028 \times (20 - MAX(T,7)) \right)$$ In addition, the highest four-day average within the 30-day averaging period should not be more than 2.5 times the criteria more than once in three years on average.
7440-39-3	Barium (Total) (b)	1.0 mg/l (1-day arithmetic average)
7440-42-8	Boron (Total) (c)	0.75 mg/l (30-day arithmetic average)
16887-00-6	Chloride (Total) (a, b, c)	Class I: 100 mg/l (30-day arithmetic average) Class IA: 175 mg/l (30-day arithmetic average) Class II and Class III: 250 mg/l (30-day arithmetic average)
7782-50-5	Chlorine Residual (Total) (a)	Acute: 0.019 mg/l Chronic: 0.011 mg/l
None	Cylindrospermopsin (d)	15 µl For Clean Water Act water quality criterion, no more than 3 excursions (10-day assessment periods) within a single recreational season in a single year.
None	Microcystins (d)	8 µl For Clean Water Act water quality criterion, no more than 3 excursions (10-day assessment periods) within a single recreational season in a single year.
7782-44-7	Dissolved Oxygen (a)	5 mg/l as a daily minimum (up to 10% of representative samples collected during any 3-year period may be less than this value provided that lethal conditions are avoided)
14797-55-8	Nitrate as N³ (a, b)	1.0 mg/l (up to 10% of samples may exceed)
14797-65-0	Nitrite as N (b)	1.0 mg/l
None	E. coli⁴ (d)	Not to exceed 126 organisms per 100 ml as a geometric mean of representative samples collected during any 30-day consecutive period, nor shall more than 10 percent of samples collected during any 30-day consecutive period individually exceed 409 organisms per 100 ml. For assessment purposes, the 30-day consecutive period shall follow the calendar month. This standard shall apply only during the recreation season May 1 to September 30.
None	pH (a)	Class I and IA: 6.5 - 9.0 (up to 10% of representative samples collected during any 3-year period may exceed this range, provided that lethal conditions are avoided). Class II and Class III: 6.0 - 9.0 (up to 10% of representative

		samples collected during any 3-year period may exceed this range, provided that lethal conditions are avoided).
108-95-2	Phenols (Total) (b)	0.3 mg/l (organoleptic criterion) (one-day arithmetic average)
7782-49-2	Selenium in Fish Flesh5 (a)	Egg-Ovary: 15.1 mg/kg Dry Weight Whole Body: 8.5 mg/kg Dry Weight Muscle: 11.3 mg/kg Dry Weight
7440-23-5	Sodium (b, c)	Class I: 50 percent of total cations as milliequivalents per liter (mEq/l) Class IA, II, and III: 60 percent of total cations as mEq/l
18785-72-3	Sulfates (Total as SO4) (b)	Class I: 250 mg/l (30-day arithmetic average) Class IA and II: 450 mg/l (30-day arithmetic average) Class III: 750 mg/l (30-day arithmetic average)
	Sulfates (Total as SO4) (a, b)	Site Specific: 750 mg/l (maximum) applies to the Sheyenne River from its headwaters to 0.1 mile downstream from Baldhill Dam 131.10(b) requirement: The water quality standards for the Red River and the portions of the Sheyenne River located downstream from the segment of the Sheyenne River to which the site-specific sulfate standard applies must continue to be maintained. The Sheyenne River from 0.1 mile downstream from Baldhill Dam to the confluence with the Red River shall not exceed 450 mg/l sulfate (total) 30-day arithmetic average, and the Red River shall not exceed 250 mg/l sulfate (total) 30-day arithmetic average after mixing downstream from the confluence of the Sheyenne River. Regulated pollution control efforts must be developed to achieve compliance with these water quality standards.
None	Temperature (a)	Eighty-five degrees Fahrenheit [29.44 degrees Celsius]. The maximum increase shall not be greater than five degrees Fahrenheit [2.78 degrees Celsius] above natural background conditions.
None	Combined radium 226 and radium 228 (Total) (b)	5 pCi/l (30-day arithmetic average)
None	Gross alpha particle activity, including radium 226, but excluding radon and uranium (b)	15 pCi/l (30-day arithmetic average)
1 CAS No. is the chemical abstract service registry number. The registry database contains records for specific substances identified by the chemical abstract service.
2 The US EPA 2018 recommended national criteria (304(a) criteria) for aluminum can be used for site-specific chronic and acute criteria when appropriate and data is available. The criteria is based upon multiple linear regression (MLR) models for fish and invertebrate species. Data requirements are pH, DOC, and total hardness to quantify the effects of these water chemistry parameters on the bioavailability and associated toxicity of aluminum to aquatic organisms.
3 The standard for nitrates (N) is intended as benchmark concentration when stream or lake specific

data is insufficient to determine the concentration that will cause excessive plant growth (eutrophication). However, in no case shall the concentration for nitrate plus nitrite N exceed 10 mg/l for any waters used as a municipal or domestic drinking water supply.

⁴ Where the E. Coli criteria are exceeded and there are natural sources, the criteria may be considered attained, provided there is reasonable basis for concluding that the indicator bacteria density attributable to anthropogenic sources is consistent with the level of water quality required by the criteria. This may be the situation, for example, in headwater streams that are minimally affected by anthropogenic activities.

⁵ Fish tissue elements are expressed as steady-state instantaneous measurement not to exceed the criteria in the table. When fish egg/ovary concentrations are measured, the egg/ovary criterion element supersedes any whole-body, or muscle criterion element. The fish flesh values in Table 1 and the water column criteria in Table 2 are independently applicable. Water column criterion elements that are derived site-specifically using an empirical bioaccumulation factor approach or a bioaccumulation mechanistic model approach, once duly established under the provisions of 40 CFR 131 will supersede the criteria in Table 2 and will be subordinate to fish tissue criterion elements when both fish and water concentrations are measured. Any site-specific water column criterion element established under the provisions of 40 CFR 131 is the applicable criterion in the absence of fish tissue measurement, or in waters with new discharges of selenium where steady state has not been achieved between water and fish tissue at the site.

(MICROGRAMS PER LITER)

CAS No.	Pollutant (Compounds)	Aquatic Life Value Classes I, IA, II, III		Human Health Value
		Acute	Chronic	Classes I, IA, II2	Class III3
71-55-6	1,1,1-Trichloroethane			10,0007	200,000
79-00-5	1,1,2-Trichloroethane4			0.55	8.9
79-34-5	1,1,2,2-Tetrachloroethane4			0.2	3
75-35-4	1,1-Dichloroethylene4			300	20,000
156-60-5	1,2-trans-Dichloroethylene7			100	4,000
120-82-1	1,2,4-Trichlorobenzene			0.071	0.076
95-50-1	1,2-Dichlorobenzene7			1,000	3,000
541-73-1	1,3-Dichlorobenzene			7	10
106-46-7	1,4-Dichlorobenzene7			300	900
107-06-2	1,2-Dichloroethane4			9.9	650
78-87-5	1,2-Dichloropropane			0.90	31
542-75-6	1,3-Dichloropropylene (1,3-Dichloropropene) (cis and trans isomers)			0.27	12
122-66-7	1,2-Diphenylhydrazine4			0.03	0.20
121-14-2	2,4-Dinitrotoluene4			0.049	1.7
95-57-8	2-Chlorophenol			30	800
120-83-2	2,4-Dichlorophenol			10	60
88-06-2	2,4,6-Trichlorophenol4			1.5	2.8
91-58-7	2-Chloronaphthalene			800	1,000
91-94-1	3,3'-Dichlorobenzidine4			0.049	0.15
105-67-9	2,4-Dimethylphenol			100	3,000
51-28-5	2,4-Dinitrophenol			10	300
94-75-7	2,4-D			1,300	12,000
72-54-8	4,4'-DDD4			0.00012	0.00012
75-55-9	4,4'-DDE4			0.000018	0.000018
50-29-3	4,4'-DDT4	0.5512	0.00112	0.000030	0.000030
534-52-1	2-Methyl-4,6-Dinitrophenol			2	30
59-50-7	3-Methyl-4-Chlorophenol			500	2,000
83-32-9	Acenaphthene			70	90
107-02-8	Acrolein	3	3	3	400
107-13-1	Acrylonitrile4			0.061	7.0
15972-60-8	Alachlor			27
309-00-2	Aldrin4	1.5		7.7E-07	7.7E-07
319-84-6	alpha-BHC4 (Hexachlorocyclohexane-alpha)			0.00036	0.00039
319-85-7	beta-BHC4 (Hexachlorocyclohexane-beta)			0.008	0.014
58-89-9	gamma-BHC (Lindane)4 (Hexachlorocyclohexane-gamma)	0.95		4.27	4.4
959-98-8	alpha-Endosulfan	0.1111	0.05611	20	30

33213-65-9	beta-Endosulfan	0.1111	0.05611	20	40
120-12-7	Anthracene (PAH)5			300	400
1332-21-4	Asbestos4,7			7,000,000 f/l	7,000,000 f/l
1912-24-9	Atrazine			37
71-43-2	Benzene4			2.1	58
92-87-5	Benzidine4			0.00014	0.011
56-55-3	Benzo(a)anthracene (PAH)4 (1,2-Benzanthracene)			0.0012	0.0013
50-32-8	Benzo(a)pyrene (PAH)4 (3,4-Benzopyrene)			0.00012	0.00013
205-99-2	Benzo(b)fluoranthene (PAH)4 (3,4-Benzofluoranthene)			0.0012	0.0013
207-08-9	Benzo(k)fluoranthene (PAH)4 (11,12-Benzofluoranthene)			0.012	0.013
12587-47-2	Beta/photon emitters			4 mrem/yr7
111-44-4	Bis(2-chloroethyl) ether4			0.030	2.2
108-60-1	Bis(2-chloro-1-Methylethyl) ether			200	4,000
117-81-7	Bis(2-ethylhexyl) phthalate4			0.32	0.37
15541-45-4	Bromate			107
75-25-2	Bromoform (HM)5 (Tribromomethane)			7.0	120
85-68-7	Butyl benzyl phthalate			0.10	0.10
63-25-2	Carbaryl (1-naphthyl-N-methycarbamate)	2.1	2.1
1563-66-2	Carbofuran			407
56-23-5	Carbon tetrachloride4 (Tetrachloromethane)			0.40	5
57-74-9	Chlordane4	1.2	0.0043	0.00031	0.00032
14998-27-7	Chlorite			1,0007
108-90-7	Chlorobenzene (Monochlorobenzene)			1007	800
124-48-1	Chlorodibromomethane (HM)5			0.80	21
67-66-3	Chloroform (HM)4 (Trichloromethane)			60	2,000
2921-88-2	Chlorpyrifos	0.083	0.041
218-01-9	Chrysene (PAH)4			0.12	0.13
57-12-5	Cyanide (total)	22	5.2	4	400
75-99-0	Dalapon			2007
103-23-1	Di(2-ethylhexyl)adipate			4007
333-41-5	Diazinon	0.17	0.17
53-70-3	Dibenzo(a,h)anthracene (PAH)4 (1,2,5,6-Dibenzanthracene)			0.00012	0.00013
67708-83-2	Dibromochloropropane			0.27
75-27-4	Dichlorobromomethane (HM)5			0.95	27
156-59-2	Dichloroethylene (cis-1,2-)			707
60-57-1	Dieldrin4	0.24	0.056	1.2E-06	1.2E-06
84-66-2	Diethyl phthalate			600	600
131-11-3	Dimethyl phthalate			2,000	2,000
84-74-2	Di-n-butyl phthalate			20	30
88-85-7	Dinoseb			77
1746-01-6	Dioxin (2,3,7,8-TCDD)4			5.00E-09	5.10E-09

85-00-7	Diquat			207
1031-07-8	Endosulfan sulfate			20	40
145-73-3	Endothall			1007
72-20-8	Endrin	0.086	0.036	0.03	0.03
7421-93-4	Endrin aldehyde			1	1
100-41-4	Ethylbenzene7			68	130
106-93-4	Ethylene dibromide (EDB)			0.057
206-44-0	Fluoranthene			20	20
86-73-7	Fluorene (PAH)5			50	70
1071-83-6	Glyphosate			7007
	Halocetic acids14			607
1024-57-3	Heptachlor epoxide4	0.26	0.0038	0.000032	0.000032
76-44-8	Heptachlor4	0.26	0.0038	0.0000059	0.0000059
118-74-1	Hexachlorobenzene4			0.000079	0.000079
87-68-3	Hexachlorobutadiene4			0.01	0.01
77-47-4	Hexachlorocyclopentadiene			4	4
67-72-1	Hexachloroethane4			0.10	0.10
193-39-5	Indeno(1,2,3-cd) pyrene (PAH)4			0.0012	0.0013
78-59-1	Isophorone4			34	1,800
72-43-5	Methoxychlor			0.02	0.02
74-83-9	Methyl bromide (HM) (Bromomethane)			100	10,000
75-09-2	Methylene chloride (HM)4 (Dichloromethane)			20	1,000
98-95-3	Nitrobenzene			10	600
62-75-9	N-Nitrosodimethylamine4			0.00069	3
621-64-7	N-Nitrosodi-n-propylamine4			0.005	0.51
86-30-6	N-Nitrosodiphenylamine4			3.3	6
84852-15-3	Nonylphenol (Isomer mixture)13	28	6.6
23135-22-0	Oxamyl (Vydate)			2007
56-38-2	Parathion	0.065	0.013
53469-21-9	PCB-1242 (Arochlor 1242)4		0.01410	0.00006410	0.00006410
126764-11-2	PCB-1016 (Arochlor 1016)4		0.01410	0.00006410	0.00006410
11104-28-2	PCB-1221 (Arochlor 1221)4		0.01410	0.00006410	0.00006410
11141-16-5	PCB-1232 (Arochlor 1232)4		0.01410	0.00006410	0.00006410
12672-29-6	PCB-1248 (Arochlor 1248)4		0.01410	0.00006410	0.00006410
11097-69-1	PCB-1254 (Arochlor 1254)4		0.01410	0.00006410	0.00006410
11096-82-5	PCB-1260 (Arochlor 1260)4		0.01410	0.00006410	0.00006410
87-86-5	Pentachlorophenol	198	158	0.03	0.04
108-95-2	Phenol			4,000	300,000
1918-02-1	Picloram			5007
129-00-0	Pyrene (PAH)5			20	30
122-34-9	Simazine			47
100-42-5	Styrene			1007
127-18-4	Tetrachloroethylene4			10	29
108-88-3	Toluene			57	520

8001-35-2	Toxaphene4	0.73	0.0002	0.0007	0.00071
688-73-3	Tributyltin	0.46	0.072
79-01-6	Trichloroethylene4			0.60	7
75-01-4	Vinyl chloride4 (Cloroethylene)			0.022	1.6
1330-20-7	Xylenes			10,0007
		Aquatic Life Value Classes I, IA, II, III		Human Health Value
CAS No.	Pollutant (Elements)	Acute	Chronic	Classes I, IA, II2	Class III3
7440-36-0	Antimony			5.6	640
7440-38-2	Arsenic7	3409	1509	107
7440-41-7	Beryllium4			47
7440-43-9	Cadmium	7.386,15	2.396,15	57
16065-83-1	Chromium (III)	5,611.706,15	268.226,15	100(total)7
18540-29-9	Chromium (VI)	16	11	100(total)7
7440-50-8	Copper	51.686,15,16	30.506,15,16	1000
7782-41-4	Fluoride			4,0007
7439-92-1	Lead	476.826	18.586	157
7439-97-6	Mercury	1.7	0.012	0.050	0.051
7440-02-0	Nickel	1,516.926,15	168.546,15	1007	4,200
7782-49-2	Selenium	20	5	507
7440-22-4	Silver	41.076,15
7440-28-0	Thallium			0.24	0.47
7440-61-1	Uranium			307
7440-66-6	Zinc	387.836,15	387.826,15	7,400	26,000

¹ Except for the aquatic life values for metals, the values given in this appendix refer to the total (dissolved plus suspended) amount of each substance unless otherwise noted. For the aquatic life values for metals, the values refer to the total recoverable method for ambient metals analyses.

² Based on two routes of exposure - ingestion of contaminated aquatic organisms and drinking water.

³ Based on one route of exposure - ingestion of contaminated aquatic organisms only.

⁴ Substance classified as a carcinogen, with the value based on an incremental risk of one additional instance of cancer in one million persons.

⁵ Chemicals which are not individually classified as carcinogens but which are contained within a class of chemicals, with carcinogenicity as the basis for the criteria derivation for that class of chemicals; an individual carcinogenicity assessment for these chemicals is pending.

⁶ Hardness dependent criteria. Value given is an example based on a CaCO₃ hardness of 400 mg/l. Criteria for each case must be calculated using the following formula:

For the Criterion Maximum Concentration (CMC):

Cadmium	CMC = e0.9789[n (hardness)] - 3.866
Chromium (III)	CMC = e0.8190[n (hardness)] + 3.7256
Copper	CMC = e0.9422[n (hardness)] - 1.7000
Lead	CMC = e1.2730[n (hardness)] - 1.4800
Nickel	CMC = e0.8460[n (hardness)] + 2.2550
Silver	CMC = e1.7200[n (hardness)] - 6.5900
Zinc	CMC = e0.8473[n (hardness)] + 0.8840

CMC = Criterion Maximum Concentration (acute exposure value)

The threshold value at or below which there should be no unacceptable effects to freshwater aquatic organisms and their uses if the one-hour concentration does not exceed that CMC value more than once every three years on the average.

For the Criterion Continuous Concentration (CCC):

Cadmium	CCC = e0.7977D (hardness) - 3.909
Chromium (III)	CCC = e0.8190D (hardness) + 0.6848
Copper	CCC = e0.8549D (hardness) - 1.7020
Lead	CCC = e1.2730D (hardness) - 4.7050
Nickel	CCC = e0.8460D (hardness) + 0.0584
Silver	No CCC criterion for silver
Zinc	CCC = e0.8473D (hardness) + 0.8840

CCC = Criterion Continuous Concentration (chronic exposure value)

The threshold value at or below which there should be no unacceptable effects to freshwater aquatic organisms and their uses if the four-day concentration does not exceed that CCC value more than once every three years on the average.

7 Safe Drinking Water Act (MCL).

8 Freshwater aquatic life criteria for pentachlorophenol are expressed as a function of pH. Values displayed in the table correspond to a pH of 7.8 and are calculated as follows:

CMC = exp [1.005 (pH) - 4.869]

CCC = exp [1.005 (pH) - 5.134]

9 This criterion applies to total arsenic.

10 This criterion applies to total PCBs (i.e., the sum of all congener or all isomer or homolog or Arochlor analyses).

11 This criterion applies to the sum of alpha-endosulfan and beta-endosulfan.

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

13 The nonylphenol criteria address CAS numbers 84852-15-3 and 25154-52-3.

14 The criterion is for a total measurement of 5 haloacetic acids, dichloroacetic acid, trichloroacetic acid, monochloroacetic acid, bromoacetic acid, and dibromoacetic acid.

15 Hardness values shall be no greater than 400 mg/l. For waters with hardness concentrations greater than 400 mg/l, the actual ambient hardness may be used where a site-specific water effect ratio has been determined consistent with the environmental protection agency's water effect ratio procedure.

16 The department will recognize the biotic ligand model as an appropriate tool for developing site-specific limits for copper as well as the water-effects ratio (WER) method.