North Carolina Administrative Code › Title 15A - Environmental Quality › Chapter 02 - Environmental Management › Subchapter B - SURFACE WATER AND WETLAND STANDARDS › Section .0200 - CLASSIFICATIONS AND WATER QUALITY STANDARDS APPLICABLE TO SURFACE WATERS AND WETLANDS OF NORTH CAROLINA › Section 02B .0208 - STANDARDS FOR TOXIC SUBSTANCES AND TEMPERATURE

Current through Register Vol. 39, No. 2, July 15, 2024
(a)
				  Toxic Substances: the concentration of toxic substances, either alone or in
				  combination with other wastes, in surface waters shall not render waters
				  injurious to aquatic life or wildlife, recreational activities, or public
				  health, nor shall it impair the waters for any designated uses. Specific
				  standards for toxic substances to protect freshwater and tidal saltwater uses
				  are listed in Rules .0211 and .0220 of this Section, respectively. The
				  narrative standard for toxic substances and numerical standards applicable to
				  all waters shall be interpreted as follows:
(1) The concentration of toxic substances
				  shall not result in chronic toxicity to aquatic life. Any levels in excess of
				  the chronic value for aquatic life shall be considered to result in chronic
				  toxicity. In the absence of direct measurements of chronic toxicity, the
				  concentration of toxic substances shall not exceed the concentration specified
				  by the fraction of the lowest LC50 value that predicts a no effect chronic
				  level as determined by the use of an acceptable Acute to Chronic Ratio (ACR) in
				  accordance with U.S. Environmental Protection Agency (EPA) "Guidelines for
				  Deriving Numerical Water Quality Criteria for the Protection of Aquatic Life
				  and its Uses." In the absence of an ACR, that toxic substance shall not exceed
				  one-one hundredth (0.01) of the lowest LC50 or, if it is demonstrated that a
				  toxic substance has a half-life of less than 96 hours, the maximum
				  concentration shall not exceed one-twentieth (0.05) of the lowest
				  LC50.
(2) The concentration of
				  toxic substances shall not exceed the level necessary to protect human health
				  through exposure routes of fish tissue consumption, water consumption,
				  recreation, or other route identified for the water body. Fish tissue
				  consumption shall include the consumption of shellfish. These concentrations of
				  toxic substances shall be determined as follows:
(A) For non-carcinogens, these concentrations
				  shall be determined using a Reference Dose (RfD) as published by the EPA
				  pursuant to Section 304(a) of the Federal Water Pollution Control Act as
				  amended, a RfD issued by the EPA as listed in the Integrated Risk Information
				  System (IRIS) file, or a RfD approved by the Director after consultation with
				  the State Health director. Water quality standards or criteria used to
				  calculate water quality based effluent limitations to protect human health
				  through the different exposure routes shall be determined as follows:
(i) Fish tissue consumption:
WQS = (RfD x RSC) x Body Weight / (FCR x BCF)
where:
WQS = water quality standard or criteria;
RfD = reference dose;
RSC = Relative Source Contribution;
FCR = fish consumption rate (based upon 17.5
					 gm/person-day);
BCF = bioconcentration factor or bioaccumulation factor
					 (BAF), as appropriate.
Pursuant to Section 304(a) of the Federal Water Pollution
					 Control Act as amended, BCF or BAF values, literature values, or site specific
					 bioconcentration data shall be based on EPA publications; FCR values shall be
					 average consumption rates for a 70 Kg adult for the lifetime of the population;
					 alternative FCR values may be used when it is considered necessary to protect
					 localized populations that may be consuming fish at a higher rate; RSC values,
					 when made available through EPA publications pursuant to Section 304(a) of the
					 Federal Clean Water Pollution Control Act to account for non-water sources of
					 exposure may be either a percentage (multiplied) or amount subtracted,
					 depending on whether multiple criteria are relevant to the chemical;
(ii) Water consumption (including
				  a correction for fish consumption):
WQS = (RfD x RSC) x Body Weight / [WCR+(FCRxBCF)]
where:
WQS = water quality standard or criteria;
RfD = reference dose;
RSC = Relative Source Contribution;
FCR = fish consumption rate (based upon 17.5
					 gm/person-day);
BCF = bioconcentration factor or bioaccumulation factor
					 (BAF), as appropriate;
WCR = water consumption rate (assumed to be two liters per
					 day for adults).
To protect sensitive groups, exposure shall be based on a
					 10 Kg child drinking one liter of water per day. Standards may also be based on
					 drinking water standards based on the requirements of the Federal Safe Drinking
					 Water Act, 42 U.S.C.
					 300(f)(g)-1. For
					 non-carcinogens, specific numerical water quality standards have not been
					 included in this Rule because water quality standards to protect aquatic life
					 for all toxic substances for which standards have been considered are more
					 stringent than numerical standards to protect human health from non-carcinogens
					 through consumption of fish. Standards to protect human health from
					 non-carcinogens through water consumption are listed under the water supply
					 classification standards in Rule .0211 of this Section. The equations listed in
					 this Subparagraph shall be used to develop water quality based effluent
					 limitations on a case-by-case basis for toxic substances that are not presently
					 included in the water quality standards. Alternative FCR values may be used
					 when it is necessary to protect localized populations that may be consuming
					 fish at a higher rate;
(B) For carcinogens, the concentrations of
				  toxic substances shall not result in unacceptable health risks and shall be
				  based on a Carcinogenic Potency Factor (CPF). An unacceptable health risk for
				  cancer shall be more than one case of cancer per one million people exposed
				  (10-6 risk level). The CPF is a measure of the
				  cancer-causing potency of a substance estimated by the upper 95 percent
				  confidence limit of the slope of a straight line calculated by the Linearized
				  Multistage Model or other appropriate model according to U.S. Environmental
				  Protection Agency Guidelines, FR 51 (185): 33992-34003; and FR 45 (231 Part V):
				  79318-79379. Water quality standards or criteria for water quality based
				  effluent limitations shall be calculated using the procedures given in this
				  Part and in Part (A) of this Subparagraph. Standards to protect human health
				  from carcinogens through water consumption are listed under the water supply
				  classification standards in Rules .0212, .0214, .0215, .0216, and .0218 of this
				  Section. Standards to protect human health from carcinogens through the
				  consumption of fish (and shellfish) only shall be applicable to all waters as
				  follows:
(i) Aldrin: 0.05 ng/l;
(ii) Arsenic: 10 ug/l;
(iii) Benzene: 51 ug/l;
(iv) Carbon tetrachloride: 1.6
				  ug/l;
(v) Chlordane: 0.8
				  ng/l;
(vi) DDT: 0.2 ng/l;
(vii) Dieldrin: 0.05 ng/l;
(viii) Dioxin: 0.000005 ng/l;
(ix) Heptachlor: 0.08 ng/l;
(x) Hexachlorobutadiene: 18 ug/l;
(xi) Polychlorinated biphenyls (total of all
				  identified PCBs and congeners): 0.064 ng/l;
(xii) Polynuclear aromatic hydrocarbons
				  (total of all PAHs): 31.1 ng/l;
(xiii) Tetrachloroethane (1,1,2,2): 4
				  ug/l;
(xiv) Tetrachloroethylene:
				  3.3 ug/L;
(xvi) Trichloroethylene:
				  30 ug/l;
(xvii) Vinyl chloride: 2.4
				  ug/l.
The values listed in Subparts (i) through (xvii) of this
					 Part may be adjusted by the Commission or its designee on a case-by-case basis
					 to account for site-specific or chemical-specific information pertaining to the
					 assumed BCF, FCR, or CPF values or other data.