Section 140. Criteria for surface water  


Latest version.
  • A. Instream water quality conditions shall not be acutely1 or chronically2 toxic except as allowed in 9VAC25-260-20 B (mixing zones). The following are definitions of acute and chronic toxicity conditions:

    "Acute toxicity" means an adverse effect that usually occurs shortly after exposure to a pollutant. Lethality to an organism is the usual measure of acute toxicity. Where death is not easily detected, immobilization is considered equivalent to death.

    "Chronic toxicity" means an adverse effect that is irreversible or progressive or occurs because the rate of injury is greater than the rate of repair during prolonged exposure to a pollutant. This includes low level, long-term effects such as reduction in growth or reproduction.

    B. The following table is a list of numerical water quality criteria for specific parameters.

    Table of Parameters6, 7

    PARAMETER
    CAS Number

    USE DESIGNATION

    AQUATIC LIFE

    HUMAN HEALTH

    FRESHWATER

    SALTWATER

    Public Water Supply3

    All Other Surface Waters4

    Acute1

    Chronic2

    Acute1

    Chronic2

    Acenapthene (μg/l)
    83329

    670

    990

    Acrolein (μg/l)
    107028

    6.1

    9.3

    Acrylonitrile (μg/l)
    107131

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.51

    2.5

    Aldrin (μg/l)
    309002

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    3.0

    1.3

    0.00049

    0.00050

    Ammonia (μg/l)
    766‑41‑7

    Chronic criterion is a 30-day average concentration not to be exceeded more than once every three (3) years on the average.(see 9VAC25-260-155)

    Anthracene (μg/l)
    120127

    8,300

    40,000

    Antimony (μg/l)
    7440360

    5.6

    640

    Arsenic (μg/l)5
    7440382

    340

    150

    69

    36

    10

    Bacteria
    (see 9VAC25-260-160 and 170)

    Barium (μg/l)
    7440393

    2,000

    Benzene (μg/l)
    71432

    Known or suspected carcinogen; human health criteria at risk level 10-5

    22

    510

    Benzidine (μg/l)
    92875

    Known or suspected carcinogen; human health criteria at risk level 10-5

    0.00086

    0.0020

    Benzo (a) anthracene (μg/l)
    56553

    Known or suspected carcinogen; human health criteria at risk level 10-5

    0.038

    0.18

    Benzo (b) fluoranthene (μg/l)
    205992

    Known or suspected carcinogen; human health criteria at risk level 10-5

    0.038

    0.18

    Benzo (k) fluoranthene (μg/l)
    207089

    Known or suspected carcinogen; human health criteria at risk level 10-5

    0.038

    0.18

    Benzo (a) pyrene (μg/l)
    50328

    Known or suspected carcinogen; human health criteria at risk level 10-5

    0.038

    0.18

    Bis2-Chloroethyl Ether
    111444

    Known or suspected carcinogen; human health criteria at risk level 10-5

    0.30

    5.3

    Bis2-Chloroisopropyl Ether (μg/l)
    108601

    1,400

    65,000

    Bis2-Ethylhexyl Phthalate (μg/l)
    117817

    Known or suspected carcinogen; human health criteria at risk level 10-5. Synonym = Di-2-Ethylhexyl Phthalate.

    12

    22

    Bromoform (μg/l)
    75252

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    43

    1,400

    Butyl benzyl phthalate (μg/l)
    85687

    1,500

    1,900

    Cadmium (μg/l)5
    7440439

    Freshwater values are a function of total hardness as calcium carbonate (CaCO3) mg/l and the WER. The minimum hardness allowed for use in the equation below shall be 25 and the maximum hardness shall be 400 even when the actual ambient hardness is less than 25 or greater than 400.

    Freshwater acute criterion (μg/l)
    WER [e {1.128[In(hardness)] – 3.828}]

    Freshwater chronic criterion (μg/l)
    WER [e {0.7852[In(hardness)] – 3.490}]

    WER = Water Effect Ratio = 1 unless determined otherwise under 9VAC25-260-140 F

    e = natural antilogarithm

    ln = natural logarithm

    3.9
    CaCO3 = 100

    1.1
    CaCO3 = 100

    40
    X WER

    8.8
    X WER

    5

    Carbon tetrachloride (μg/l)
    56235

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    2.3

    16

    Chlordane (μg/l)
    57749

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    2.4

    0.0043

    0.09

    0.0040

    0.0080

    0.0081

    Chloride (μg/l)
    16887006

    Human Health criterion to maintain acceptable taste and aesthetic quality and applies at the drinking water intake.

    Chloride criteria do not apply in Class II transition zones (see subsection C of this section).

    860,000

    230,000

    250,000

    Chlorine, Total Residual (μg/l)
    7782505

    In DGIF class i and ii trout waters (9VAC25-260-390 through 9VAC25-260-540) or waters with threatened or endangered species are subject to the halogen ban (9VAC25-260-110).

    19

    See 9VAC25-260-110

    11

    See 9VAC25-260-110

    Chlorine Produced Oxidant (μg/l)
    7782505

    13

    7.5

    Chlorobenzene (μg/l)
    108907

    130

    1,600

    Chlorodibromomethane (μg/l)
    124481

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    4.0

    130

    Chloroform (μg/l)
    67663

    340

    11,000

    2-Chloronaphthalene (μg/l)
    91587

    1,000

    1,600

    2-Chlorophenol (μg/l)
    95578

    81

    150

    Chlorpyrifos (μg/l)
    2921882

    0.083

    0.041

    0.011

    0.0056

    Chromium III (μg/l)5
    16065831

    Freshwater values are a function of total hardness as calcium carbonate CaCO3 mg/l and the WER. The minimum hardness allowed for use in the equation below shall be 25 and the maximum hardness shall be 400 even when the actual ambient hardness is less than 25 or greater than 400.

    Freshwater acute criterion μg/l

    WER [e{0.8190[In(hardness)]+3.7256}] (CFa)

    Freshwater chronic criterion μg/l
    WER [e{0.8190[In(hardness)]+0.6848}] (CFc)

    WER = Water Effect Ratio = 1 unless determined otherwise under 9VAC25-260-140.F

    e = natural antilogarithm

    ln = natural logarithm

    CF = conversion factor a (acute) or c (chronic)

    CFa= 0.316

    CFc=0.860

    570
    (CaCO3 = 100)

    74
    (CaCO3 = 100)

    100
    (total Cr)

    Chromium VI (μg/l)5
    18540299

    16

    11

    1,100

    50

    Chrysene (μg/l)
    218019

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.0038

    0.018

    Copper (μg/l)5
    7440508

    Freshwater values are a function of total hardness as calcium carbonate CaCO3 mg/l and the WER. The minimum hardness allowed for use in the equation below shall be 25 and the maximum hardness shall be 400 even when the actual ambient hardness is less than 25 or greater than 400.

    Freshwater acute criterion (μg/l)

    WER [e {0.9422[In(hardness)]-1.700}] (CFa)

    Freshwater chronic criterion (μg/l)
    WER [e {0.8545[In(hardness)]-1.702}] (CFc)

    WER = Water Effect Ratio = 1 unless determined otherwise under 9VAC25-260-140 F.

    e = natural antilogarithm

    ln = natural logarithm

    CF = conversion factor a (acute) or c (chronic)

    CFa = 0.960

    CFc = 0.960

    Acute saltwater criterion is a 24-hour average not to be exceeded more than once every three years on the average.

    13
    CaCO 3 = 100

    9.0
    CaCO3 = 100

    9.3
    X WER

    6.0
    X WER

    1,300

    Cyanide, Free (μg/l)
    57125

    22

    5.2

    1.0

    1.0

    140

    16,000

    DDD (μg/l)
    72548

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.0031

    0.0031

    DDE (μg/l)
    72559

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.0022

    0.0022

    DDT (μg/l)
    50293

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    Total concentration of DDT and metabolites shall not exceed aquatic life criteria.

    1.1

    0.0010

    0.13

    0.0010

    0.0022

    0.0022

    Demeton (μg/l)
    8065483

    0.1

    0.1

    Diazinon (μg/l)
    333415

    0.17

    0.17

    0.82

    0.82

    Dibenz (a, h) anthracene (μg/l)
    53703

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.038

    0.18

    1,2-Dichlorobenzene (μg/l)
    95501

    420

    1,300

    1,3-Dichlorobenzene (μg/l)
    541731

    320

    960

    1,4 Dichlorobenzene (μg/l)
    106467

    63

    190

    3,3 Dichlorobenzidine
    91941

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.21

    0.28

    Dichlorobromomethane (μg/l)
    75274

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    5.5

    170

    1,2 Dichloroethane (μg/l)
    107062

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    3.8

    370

    1,1 Dichloroethylene (μg/l)
    75354

    330

    7,100

    1,2-trans-dichloroethylene (μg/l)
    156605

    140

    10,000

    2,4 Dichlorophenol (μg/l)
    120832

    77

    290

    2,4 Dichlorophenoxy acetic acid (2,4-D) (μg/l)
    94757

    100

    1,2-Dichloropropane (μg/l)
    78875

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    5.0

    150

    1,3-Dichloropropene (μg/l)
    542756

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    3.4

    210

    Dieldrin (μg/l)
    60571

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.24

    0.056

    0.71

    0.0019

    0.00052

    0.00054

    Diethyl Phthalate (μg/l)
    84662

    17,000

    44,000

    2,4 Dimethylphenol (μg/l)
    105679

    380

    850

    Dimethyl Phthalate (μg/l)
    131113

    270,000

    1,100,000

    Di-n-Butyl Phthalate (μg/l)
    84742

    2,000

    4,500

    2,4 Dinitrophenol (μg/l)
    51285

    69

    5,300

    2-Methyl-4,6-Dinitrophenol (μg/l)
    534521

    13

    280

    2,4 Dinitrotoluene (μg/l)
    121142

    Known or suspected carcinogen; human health criteria at risk level 10-5

    1.1

    34

    Dioxin 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (μg/l)
    1746016

    5.0 E-8

    5.1 E-8

    1,2-Diphenylhydrazine (μg/l)
    122667

    Known or suspected carcinogen; human health criteria at risk level 10-5

    0.36

    2.0

    Dissolved Oxygen (μg/l)
    (See 9VAC25-260-50)

    Alpha-Endosulfan (μg/l)
    959988

    Total concentration alpha and beta-endosulfan shall not exceed aquatic life criteria.

    0.22

    0.056

    0.034

    0.0087

    62

    89

    Beta-Endosulfan (μg/l)
    33213659

    Total concentration alpha and beta-endosulfan shall not exceed aquatic life criteria.

    0.22

    0.056

    0.034

    0.0087

    62

    89

    Endosulfan Sulfate (μg/l)
    1031078

    62

    89

    Endrin (μg/l)
    72208

    0.086

    0.036

    0.037

    0.0023

    0.059

    0.060

    Endrin Aldehyde (μg/l)
    7421934

    0.29

    0.30

    Ethylbenzene (μg/l)
    100414

    530

    2,100

    Fecal Coliform
    (see 9VAC25-260-160

    Fluoranthene (μg/l)
    206440

    130

    140

    Fluorene (μg/l)
    86737

    1,100

    5,300

    Foaming Agents (μg/l)
    Criterion measured as methylene blue active substances. Criterion to maintain acceptable taste, odor, or aesthetic quality of drinking water and applies at the drinking water intake.

    500

    Guthion (μg/l)
    86500

    0.01

    0.01

    Heptachlor (μg/l)
    76448

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.52

    0.0038

    0.053

    0.0036

    0.00079

    0.00079

    Heptachlor Epoxide (μg/l)
    1024573

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.52

    0.0038

    0.053

    0.0036

    0.00039

    0.00039

    Hexachlorobenzene (μg/l)
    118741

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.0028

    0.0029

    Hexachlorobutadiene (μg/l)
    87683
    Known or suspected carcinogen; human health criteria at risk level 10-5.

    4.4

    180

    Hexachlorocyclohexane Alpha-BHC (μg/l)
    319846

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.026

    0.049

    Hexachlorocyclohexane Beta-BHC (μg/l)
    319857

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.091

    0.17

    Hexachlorocyclohexane (μg/l) (Lindane)

    Gamma-BHC
    58899

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.95

    0.16

    0.98

    1.8

    Hexachlorocyclopentadiene (μg/l)
    77474

    40

    1,100

    Hexachloroethane (μg/l)
    67721

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    14

    33

    Hydrogen sulfide (μg/l)
    7783064

    2.0

    2.0

    Indeno (1,2,3,-cd) pyrene (μg/l)
    193395

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.038

    0.18

    Iron (μg/l)
    7439896

    Criterion to maintain acceptable taste, odor or aesthetic quality of drinking water and applies at the drinking water intake.

    300

    Isophorone (μg/l)
    78591

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    350

    9,600

    Kepone (μg/l)
    143500

    zero

    zero

    Lead (μg/l)5
    7439921

    Freshwater values are a function of total hardness as calcium carbonate CaCO3 mg/l and the water effect ratio. The minimum hardness allowed for use in the equation below shall be 25 and the maximum hardness shall be 400 even when the actual ambient hardness is less than 25 or greater than 400.

    Freshwater acute criterion (μg/l)
    WER [e {1.273[In(hardness)]-1.084}]

    Freshwater chronic criterion (μg/l)
    WER [e {1.273[In(hardness)]-3.259}]

    WER = Water Effect Ratio = 1 unless determined otherwise under 9VAC25-260-140 F

    e = natural antilogarithm

    ln = natural logarithm

    120
    CaCO3 = 100

    14
    CaCO3 = 100

    240 X WER

    9.3 X WER

    15

    Malathion (μg/l)
    121755

    0.1

    0.1

    Manganese (μg/l)
    7439965

    Criterion to maintain acceptable taste, odor or aesthetic quality of drinking water and applies at the drinking water intake.

    50

    Mercury (μg/l) 5
    7439976

    1.4

    0.77

    1.8

    0.94

    Methyl Bromide (μg/l)
    74839

    47

    1,500

    Methyl Mercury (Fish Tissue Criterion mg/kg) 8
    22967926

    0.30

    0.30

    Methylene Chloride (μg/l)
    75092

    Known or suspected carcinogen; human health criteria at risk level 10-5 Synonym = Dichloromethane

    46

    5,900

    Methoxychlor (μg/l)
    72435

    0.03

    0.03

    100

    Mirex (μg/l)
    2385855

    zero

    zero

    Nickel (μg/l)5
    744002

    Freshwater values are a function of total hardness as calcium carbonate CaCO3 mg/l and the WER. The minimum hardness allowed for use in the equation below shall be 25 and the maximum hardness shall be 400 even when the actual ambient hardness is less than 25 or greater than 400.

    Freshwater acute criterion μg/l
    WER [e {0.8460[In(hardness)] + 1.312}] (CFa)

    Freshwater chronic criterion (μg/l)
    WER [e {0.8460[In(hardness)] - 0.8840}] (CFc)

    WER = Water Effect Ratio = 1 unless determined otherwise under 9VAC25-260-140 F

    e = natural antilogarithm

    ln = natural logarithm

    CF = conversion factor a (acute) or c (chronic)

    CFa = 0.998

    CFc = 0.997

    180
    CaCO3 = 100

    20
    CaCO3 = 100

    74 X WER

    8.2 X WER

    610

    4,600

    Nitrate as N (μg/l)
    14797558

    10,000

    Nitrobenzene (μg/l)
    98953

    17

    690

    N-Nitrosodimethylamine (μg/l)
    62759

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.0069

    30

    N-Nitrosodiphenylamine (μg/l)
    86306

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    33

    160 60

    N-Nitrosodi-n-propylamine (μg/l)
    621647

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.050

    5.1

    Nonylphenol
    1044051

    28

    6.6

    7.0

    1.7

    Parathion (μg/l)
    56382

    0.065

    0.013

    PCB Total (μg/l)
    1336363

    Known or suspected carcinogen; human health criteria at risk level 10-5

    0.014

    0.030

    0.00064

    0.00064

    Pentachlorophenol (μg/l)
    87865

    Known or suspected carcinogen; human health criteria risk level at 10-5

    Freshwater acute criterion (μg/l)
    e (1.005(pH)-4.869)

    Freshwater chronic criterion (μg/l)
    e (1.005(pH)-5.134)

    8.7
    pH = 7.0

    6.7
    pH = 7.0

    13

    7.9

    2.7

    30

    pH
    See 9VAC25-260-50

    Phenol (μg/l)
    108952

    10,000

    860,000

    Phosphorus Elemental (μg/l)
    7723140

    0.10

    Pyrene (μg/l)
    129000

    830

    4,000

    Radionuclides

    Gross Alpha Particle Activity (pCi/L)

    15

    Beta Particle & Photon Activity (mrem/yr) (formerly man-made radionuclides)

    4

    Combined Radium 226 and 228 (pCi/L)

    5

    Uranium (μg/L)

    30

    Selenium (μg/l)5
    7782492

    WER shall not be used for freshwater acute and chronic criteria. Freshwater criteria expressed as total recoverable.

    20

    5.0

    290 X WER

    71
    X WER

    170

    4,200

    Silver (μg/l)5
    7440224

    Freshwater values are a function of total hardness as calcium carbonate (CaCO3) mg/l and the WER. The minimum hardness allowed for use in the equation below shall be 25 and the maximum hardness shall be 400 even when the actual ambient hardness is less than 25 or greater than 400.

    Freshwater acute criterion (μg/l)
    WER [e {1.72[In(hardness)]-6.52}] (CFa)

    WER = Water Effect Ratio = 1 unless determined otherwise under 9VAC25-260-140 F

    e = natural antilogarithm

    ln = natural logarithm

    CF = conversion factor a (acute) or c (chronic)

    CFa = 0.85

    3.4; CaCO3 = 100

    1.9 X WER

    Sulfate (μg/l)

    Criterion to maintain acceptable taste, odor or aesthetic quality of drinking water and applies at the drinking water intake.

    250,000

    Temperature

    See 9VAC25-260-50

    1,1,2,2-Tetrachloroethane (μg/l)
    79345

    Known or suspected carcinogen; human health criteria at risk level 10-5)

    1.7

    40

    Tetrachloroethylene (μg/l)
    127184

    Known or suspected carcinogen; human health criteria at risk level 10-5)

    6.9

    33

    Thallium (μg/l)
    7440280

    0.24

    0.47

    Toluene (μg/l)
    108883

    510

    6,000

    Total Dissolved Solids (μg/l)
    Criterion to maintain acceptable taste, odor or aesthetic quality of drinking water and applies at the drinking water intake.

    500,000

    Toxaphene (μg/l)
    8001352

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.73

    0.0002

    0.21

    0.0002

    0.0028

    0.0028

    Tributyltin (μg/l)
    60105

    0.46

    0.072

    0.42

    0.0074

    1, 2, 4 Trichlorobenzene (μg/l)
    120821

    35

    70

    1,1,2-Trichloroethane (μg/l)
    79005

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    5.9

    160

    Trichloroethylene (μg/l)
    79016

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    25

    300

    2, 4, 6-Trichlorophenol
    88062

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    14

    24

    2-(2, 4, 5-Trichlorophenoxy propionic acid (Silvex) (μg/l)
    93721

    50

    Vinyl Chloride (μg/l)
    75014

    Known or suspected carcinogen; human health criteria at risk level 10-5.

    0.25

    24

    Zinc (μg/l)5
    744066

    Freshwater values are a function of total hardness as calcium carbonate (CaCO3) mg/l and the WER. The minimum hardness allowed for use in the equation below shall be 25 and the maximum, hardness shall be 400 even when the actual ambient hardness is less than 25 or greater than 400.

    Freshwater acute criterion μg/l
    WER [e {0.8473[In(hardness)]+0.884}] (CFa)

    Freshwater chronic criterion μg/l
    WER [e{0.8473[In(hardness)]+0.884}] (CFc)

    WER = Water Effect Ratio = 1 unless determined otherwise under 9VAC25-260-140 F

    e = base e exponential function.

    ln = log normal function

    CFa = 0.978

    CFc = 0.986

    120 CaCO3 = 100

    120 CaCO3 = 100

    90
    X WER

    81
    X WER

    7,400

    26,000

    1One hour average concentration not to be exceeded more than once every 3 years on the average, unless otherwise noted.

    2Four-day average concentration not to be exceeded more than once every 3 years on the average, unless otherwise noted.

    3Criteria have been calculated to protect human health from toxic effects through drinking water and fish consumption, unless otherwise noted and apply in segments designated as PWS in 9VAC25-260-390-540.

    4Criteria have been calculated to protect human health from toxic effects through fish consumption, unless otherwise noted and apply in all other surface waters not designated as PWS in 9VAC25-260-390-540.

    5Acute and chronic saltwater and freshwater aquatic life criteria apply to the biologically available form of the metal and apply as a function of the pollutant's water effect ratio (WER) as defined in 9VAC25-260-140 F (WER X criterion). Metals measured as dissolved shall be considered to be biologically available, or, because local receiving water characteristics may otherwise affect the biological availability of the metal, the biologically available equivalent measurement of the metal can be further defined by determining a Water Effect Ratio (WER) and multiplying the numerical value shown in 9VAC25-260-140 B by the WER. Refer to 9VAC25-260-140 F. Values displayed above in the table are examples and correspond to a WER of 1.0. Metals criteria have been adjusted to convert the total recoverable fraction to dissolved fraction using a conversion factor. Criteria that change with hardness have the conversion factor listed in the table above.

    6The flows listed below are default design flows for calculating steady state waste load allocations unless statistically valid methods are employed which demonstrate compliance with the duration and return frequency of the water quality criteria.

    Aquatic Life:

    Acute criteria

    1Q10

    Chronic criteria

    7Q10

    Chronic criteria (ammonia)

    30Q10

    Human Health:

    Noncarcinogens

    30Q5

    Carcinogens

    Harmonic mean

    The following are defined for this section:

    "1Q10" means the lowest flow averaged over a period of one day which on a statistical basis can be expected to occur once every 10 climatic years.

    "7Q10" means the lowest flow averaged over a period of seven consecutive days that can be statistically expected to occur once every 10 climatic years.

    "30Q5" means the lowest flow averaged over a period of 30 consecutive days that can be statistically expected to occur once every five climatic years.

    "30Q10" means the lowest flow averaged over a period of 30 consecutive days that can be statistically expected to occur once every 10 climatic years.

    "Averaged" means an arithmetic mean.

    "Climatic year" means a year beginning on April 1 and ending on March 31.

    7The criteria listed in this table are two significant digits. For other criteria that are referenced to other sections of this regulation in this table, all numbers listed as criteria values are significant.

    8The fish tissue criterion for methylmercury applies to a concentration of 0.30 mg/kg as wet weight in edible tissue for species of fish and/or shellfish resident in a waterbody that are commonly eaten in the area and have commercial, recreational, or subsistence value.

    C. Application of freshwater and saltwater numerical criteria. The numerical water quality criteria listed in subsection B of this section (excluding dissolved oxygen, pH, temperature) shall be applied according to the following classes of waters (see 9VAC25-260-50) and boundary designations:

    CLASS OF WATERS

    NUMERICAL CRITERIA

    I and II (Estuarine Waters)

    Saltwater criteria apply

    II (Transition Zone)

    More stringent of either the freshwater or saltwater criteria apply

    II (Tidal Freshwater), III, IV, V, VI and VII

    Freshwater criteria apply

    The following describes the boundary designations for Class II, (estuarine, transition zone and tidal freshwater waters) by river basin:

    1. Rappahannock Basin. Tidal freshwater is from the fall line of the Rappahannock River to the upstream boundary of the transition zone including all tidal tributaries that enter the tidal freshwater Rappahannock River.

    Transition zone upstream boundary – 38° 4' 56.59"/-76° 58' 47.93" (430 feet east of Hutchinson Swamp) to 38° 5' 23.33"/-76° 58' 24.39" (0.7 miles upstream of Peedee Creek).

    Transition zone downstream boundary - 37° 58' 45.80"/-76° 55' 28.75" (1,000 feet downstream of Jenkins Landing) to 37° 59' 20.07/-76° 53' 45.09" (0.33 miles upstream of Mulberry Point). All tidal waters that enter the transition zone are themselves transition zone waters.

    Estuarine waters are from the downstream boundary of the transition zone to the mouth of the Rappahannock River (Buoy 6), including all tidal tributaries that enter the estuarine waters of the Rappahannock River.

    2. York Basin. Tidal freshwater is from the fall line of the Mattaponi River at N37° 47' 20.03"/W77° 6' 15.16" (800 feet upstream of the Route 360 bridge in Aylett) to the upstream boundary of the Mattaponi River transition zone, and from the fall line of the Pamunkey River at N37° 41' 22.64" /W77° 12' 50.83" (2,000 feet upstream of Totopotomy Creek) to the upstream boundary of the Pamunkey River transition zone, including all tidal tributaries that enter the tidal freshwaters of the Mattaponi and Pamunkey Rivers.

    Mattaponni River transition zone upstream boundary – N37° 39' 29.65"/W76° 52' 53.29" (1,000 feet upstream of Mitchell Hill Creek) to N37° 39' 24.20"/W76° 52' 55.87" (across from Courthouse Landing). Mattaponi River transition zone downstream boundary – N37° 32' 19.76"/W76° 47' 29.41" (old Lord Delaware Bridge, west side) to N37° 32' 13.25"/W76° 47' 10.30" (old Lord Delaware Bridge, east side).

    Pamunkey River transition zone upstream boundary – N37° 32' 36.63"/W76° 58' 29.88" (Cohoke Marsh, 0.9 miles upstream of Turkey Creek) to N37° 32' 36.51"/W76° 58' 36.48" (0.75 miles upstream of creek at Cook Landing). Pamunkey River transition zone downstream boundary – N37° 31' 57.90"/ 76° 48' 38.22" (old Eltham Bridge, west side) to N37° 32' 6.25"/W76 48' 18.82" (old Eltham Bridge, east side).

    All tidal tributaries that enter the transition zones of the Mattaponi and Pamunkey Rivers are themselves in the transition zone.

    Estuarine waters are from the downstream boundary of the transition zones of the Mattaponi and Pamunkey Rivers to the mouth of the York River (Tue Marsh Light) including all tidal tributaries that enter the estuarine waters of the York River.

    3. James Basin. Tidal Freshwater is from the fall line of the James River in the City of Richmond upstream of Mayo Bridge to the upstream boundary of the transition zone, including all tidal tributaries that enter the tidal freshwater James River.

    James River transition zone upstream boundary – N37° 14' 28.25"/W76° 56' 44.47" (at Tettington) to N37° 13' 38.56"/W76° 56' 47.13" 0.3 miles downstream of Sloop Point.

    Chickahominy River transition zone upstream boundary – N37° 25' 44.79"/W77° 1' 41.76" (Holly Landing).

    Transition zone downstream boundary – N37° 12' 7.23"/W76° 37' 34.70" (near Carters Grove Home, 1.25 downstream of Grove Creek) to N37° 9' 17.23"/W76° 40' 13.45" (0.7 miles upstream of Hunnicutt Creek). All tidal waters that enter the transition zone are themselves transition zone waters.

    Estuarine waters are from the downstream transition zone boundary to the mouth of the James River (Buoy 25) including all tidal tributaries that enter the estuarine waters of the James River.

    4. Potomac Basin. Tidal Freshwater includes all tidal tributaries that enter the Potomac River from its fall line at the Chain Bridge (N38° 55' 46.28"/W77° 6' 59.23") to the upstream transition zone boundary near Quantico, Virginia.

    Transition zone includes all tidal tributaries that enter the Potomac River from N38° 31' 27.05"/W77° 17' 7.06" (midway between Shipping Point and Quantico Pier) to N38° 23' 22.78"/W77° 1' 45.50" (one mile southeast of Mathias Point).

    Estuarine waters includes all tidal tributaries that enter the Potomac River from the downstream transition zone boundary to the mouth of the Potomac River (Buoy 44B).

    5. Chesapeake Bay, Atlantic Ocean, and small coastal basins. Estuarine waters include the Atlantic Ocean tidal tributaries, and the Chesapeake Bay and its small coastal basins from the Virginia state line to the mouth of the bay (a line from Cape Henry drawn through Buoys 3 and 8 to Fishermans Island), and its tidal tributaries, excluding the Potomac tributaries and those tributaries listed above.

    6. Chowan River Basin. Tidal freshwater includes the Northwest River and its tidal tributaries from the Virginia-North Carolina state line to the free flowing portion, the Blackwater River and its tidal tributaries from the Virginia-North Carolina state line to the end of tidal waters at approximately state route 611 at river mile 20.90, the Nottoway River and its tidal tributaries from the Virginia-North Carolina state line to the end of tidal waters at approximately Route 674, and the North Landing River and its tidal tributaries from the Virginia-North Carolina state line to the Great Bridge Lock.

    Transition zone includes Back Bay and its tributaries in the City of Virginia Beach to the Virginia-North Carolina state line.

    D. Site-specific modifications to numerical water quality criteria.

    1. The board may consider site-specific modifications to numerical water quality criteria in subsection B of this section where the applicant or permittee demonstrates that the alternate numerical water quality criteria are sufficient to protect all designated uses (see 9VAC25-260-10) of that particular surface water segment or body.

    2. Any demonstration for site-specific human health criteria shall be restricted to a reevaluation of the bioconcentration or bioaccumulation properties of the pollutant. The exceptions to this restriction are for site-specific criteria for taste, odor, and aesthetic compounds noted by double asterisks in subsection B of this section and nitrates.

    3. Procedures for promulgation and review of site-specific modifications to numerical water quality criteria resulting from subdivisions 1 and 2 of this subsection.

    a. Proposals describing the details of the site-specific study shall be submitted to the board's staff for approval prior to commencing the study.

    b. Any site-specific modification shall be promulgated as a regulation in accordance with the Administrative Process Act. All site-specific modifications shall be listed in 9VAC25-260-310 (Special standards and requirements).

    E. Variances to water quality standards.

    1. A variance from numeric criteria may be granted to a discharger if it can be demonstrated that one or more of the conditions in 9VAC25-260-10 H limit the attainment of one or more specific designated uses.

    a. Variances shall apply only to the discharger to whom they are granted and shall be reevaluated and either continued, modified or revoked at the time of permit issuance. At that time the permittee shall make a showing that the conditions for granting the variance still apply.

    b. Variances shall be described in the public notice published for the permit. The decision to approve a variance shall be subject to the public participation requirements of the Virginia Pollutant Discharge Elimination System (VPDES) Permit Regulation, 9VAC25-31 (Permit Regulation).

    c. Variances shall not prevent the maintenance and protection of existing uses or exempt the discharger or regulated activity from compliance with other appropriate technology or water quality-based limits or best management practices.

    d. Variances granted under this section shall not apply to new discharges.

    e. Variances shall be submitted by the department's Division of Scientific Research or its successors to the Environmental Protection Agency for review and approval/disapproval.

    f. A list of variances granted shall be maintained by the department's Division of Scientific Research or its successors.

    2. None of the variances in this subsection shall apply to the halogen ban section (9VAC25-260-110) or temperature criteria in 9VAC25-260-50 if superseded by § 316(a) of the Clean Water Act requirements. No variances in this subsection shall apply to the criteria that are designed to protect human health from carcinogenic and noncarcinogenic toxic effects (subsection B of this section) with the exception of the metals, and the taste, odor, and aesthetic compounds noted by double asterisks and nitrates, listed in subsection B of this section.

    F. Water effect ratio.

    1. A water effects ratio (WER) shall be determined by measuring the effect of receiving water (as it is or will be affected by any discharges) on the bioavailability or toxicity of a metal by using standard test organisms and a metal to conduct toxicity tests simultaneously in receiving water and laboratory water. The ratio of toxicities of the metal(s) in the two waters is the WER (toxicity in receiving water divided by toxicity in laboratory water = WER). Once an acceptable WER for a metal is established, the numerical value for the metal in subsection B of this section is multiplied by the WER to produce an instream concentration that will protect designated uses. This instream concentration shall be utilized in permitting decisions.

    2. The WER shall be assigned a value of 1.0 unless the applicant or permittee demonstrates to the department's satisfaction in a permit proceeding that another value is appropriate, or unless available data allow the department to compute a WER for the receiving waters. The applicant or permittee is responsible for proposing and conducting the study to develop a WER. The study may require multiple testing over several seasons. The applicant or permittee shall obtain the department's Division of Scientific Research or its successor approval of the study protocol and the final WER.

    3. The Permit Regulation at 9VAC25-31-230 C requires that permit limits for metals be expressed as total recoverable measurements. To that end, the study used to establish the WER may be based on total recoverable measurements of the metals.

    4. The Environmental Protection Agency views the WER in any particular case as a site-specific criterion. Therefore, the department's Division of Scientific Research or its successor shall submit the results of the study to the Environmental Protection Agency for review and approval/disapproval within 30 days of the receipt of certification from the state's Office of the Attorney General. Nonetheless, the WER is established in a permit proceeding, shall be described in the public notice associated with the permit proceeding, and applies only to the applicant or permittee in that proceeding. The department's action to approve or disapprove a WER is a case decision, not an amendment to the present regulation.

    The decision to approve or disapprove a WER shall be subject to the public participation requirements of the Permit Regulation, 9VAC25-31-260 et seq. A list of final WERs will be maintained by the department's Division of Scientific Research or its successor.

    5. A WER shall not be used for the freshwater and saltwater chronic mercury criteria or the freshwater acute and chronic selenium criteria.

Historical Notes

Derived from VR680-21-01.14B, eff. May 20, 1992; amended, Volume 14, Issue 04, eff. December 10, 1997; Errata, 14:12 VA.R. 1937 March 2, 1998; amended, Virginia Register Volume 19, Issue 23, eff. August 27, 2003; Volume 20, Issue 09, eff. February 12, 2004; amended, Virginia Register Volume 26, Issue 12, eff. February 1, 2010; Errata, 26:12 VA.R. 2065 February 15, 2010.

Statutory Authority

§ 62.1-44.15 of the Code of Virginia; 33 USC § 1251 et seq. of the federal Clean Water Act; 40 CFR Part 131.