Indiana Administrative Code
Title 327 - WATER POLLUTION CONTROL DIVISION
Article 2 - WATER QUALITY STANDARDS
Rule 1 - Water Quality Standards Applicable to All State Waters Except Waters of the State Within the Great Lakes System
Section 1-8.3 - Determination of chronic aquatic criteria (CAC)
Universal Citation: 327 IN Admin Code 1-8.3
Current through March 20, 2024
Authority: IC 13-14-8; IC 13-14-9; IC 13-18-3
Affected: IC 13-18-4
Sec. 8.3.
In order to ensure that the concentration of a substance or combination of substances does not produce chronic effects on aquatic organisms, a chronic aquatic criterion (CAC) will be determined by one (1) of the following methods:
(1) The following for Method 1:
(A) If no CAC is
given for the substance in section 6(a)(3), Table 6-1 of this rule, section
6(a)(3), Table 6-2 of this rule, or section 6(a)(5) of this rule, a CAC can be
calculated using the procedures in this subdivision.
(B) The CAC is derived in the same manner as
the FAV in section 8.2(1) of this rule by substituting CAC for FAV, chronic for
acute, MATC (maximum acceptable toxicant concentration) for
LC50, SMCV (species mean chronic value) for SMAV, and
GMCV (genus mean chronic value) for GMAV.
(C) If chronic toxicity data are not
available for at least five (5) North American freshwater genera meeting the
requirements in section 8.2(1)(B) of this rule, go to subdivision
(2).
(2) The following for Method 2:
(A) The CAC can be calculated
by dividing the FAV by an acute-chronic ratio (or geometric mean of the
acute-chronic ratios if more than one (1) is available) for at least one (1)
North American freshwater species.
(B) If no acute-chronic ratio is available
for at least one (1) North American freshwater species, go to subdivision
(3).
(3) The following for Method 3:
(A) The CAC can be calculated
by dividing the FAV by a factor of forty-five (45). If, for a commercially,
recreationally, or ecologically important species, the geometric mean of the
chronic values is lower than the calculated CAC, then that geometric mean is
used as the CAC instead of the calculated CAC.
(B) If the data needed in clause (A) are not
available, no CAC can be calculated and the discharger will be required to
develop the minimum data base necessary to calculate the CAC (ninety-six (96)
hour LC50 for rainbow trout, fathead minnow, or bluegill
and a forty-eight (48) hour LC50 for a
daphnid).
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