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 1-8.2 - Determination of acute aquatic criteria (AAC)

Current through July 10, 2024
Authority: IC 13-14-8; IC 13-14-9; IC 13-18-3
Affected: IC 13-18-4
Sec. 8.2.
In order to ensure that the concentration of a substance or
				  combination of substances does not become acutely toxic to aquatic organisms,
				  an acute aquatic criterion (AAC) will be determined by one (1) of the following
				  methods:
(1) The following for Method
				1:
(A) If no AAC is available 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, for the substance, an AAC can be calculated using
				the procedures in this subdivision.
(B) An acute criterion can be calculated
				using modified U.S. EPA procedures when acute toxicity data are available for
				at least five (5) North American genera of freshwater organisms, including
				representatives of the following families:
(i)
				The family Salmonidae.
(ii) The
				family Cyprinidae or Centrarchidae.
(iii) Another family, not represented in item
				(i) or (ii), in the Class Osteichthyes.
(iv) The family Daphnidae.
(v) Another aquatic macroinvertebrate
				family.
(C) Resident
				species data are preferred for the required data set in clause (B). If one (1)
				or more of the required families are not a site resident, the requirement may
				be waived and appropriate substitution will be made. If data are not available
				for resident species, data for nonresident species may be substituted and will
				be assumed to be representative of resident species. The AAC is calculated
				using the following procedures:
(i) If the
				acute toxicity of the chemical has not been adequately shown to be related to a
				water quality characteristic, such as hardness, pH, or temperature, the AAC is
				calculated using the following procedures:
(AA) For each species for which at least one
				(1) acute value is available, the species mean acute value (SMAV) is calculated
				as the geometric mean of the results of all tests in which the concentrations
				of test material were stable as shown by measured values. For a species for
				which no such result is available, the SMAV should be calculated as the
				geometric mean of all available acute values, for example, results of
				flow-through tests in which the concentrations were not measured and results of
				static and renewal tests based on initial concentrations of test
				material.
(BB) For each genus for
				which one (1) or more SMAVs are available, the genus mean acute value (GMAV) is
				calculated as the geometric mean of the SMAVs available for the
				genus.
(CC) The GMAVs are ordered
				from high to low.
(DD) Ranks (R)
				are assigned to the GMAVs from "1" for the lowest to "N" for the highest. If
				two (2) or more GMAVs are identical, successive ranks are arbitrarily
				assigned.
(EE) The cumulative
				probability, P, is calculated for each GMAV as R/(N + 1).
(FF) The (T) GMAVs (T = 2 for N = 5; T = 3
				for N = 6 or 7; T = 4 for N = 8 or greater) are selected that have cumulative
				probabilities closest to five-hundredths (0.05). If there are fewer than
				fifty-nine (59) GMAVs, these will always be the two (2) (for N = 5), three (3)
				(for N = 6 or 7), or four (4) (for N = 8 or greater) lowest GMAVs.
(GG) Using the selected GMAVs and Ps, the
				final acute value (FAV) is calculated as:
S2
=
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							 image
L
=
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							 image
A
=
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FAV
=
eA
AAC
=
FAV/2
*E
=
Summation
(HH)
				If, for a commercially, recreationally, or ecologically important species, the
				geometric mean of the acute values from flow-through tests in which the
				concentrations of test material were measured is lower than the calculated FAV,
				then that geometric mean is used as the FAV instead of the calculated
				FAV.
(ii) If data are
				available to show that acute toxicity to two (2) or more species is similarly
				related to a water quality characteristic, the AAC is calculated using the
				procedures as follows:
(AA) For each species
				for which comparable acute toxicity values are available at two (2) or more
				different values of the water quality characteristic, a least squares
				regression of the acute toxicity values on the corresponding values of the
				water quality characteristic is performed to obtain the slope of the curve that
				describes the relationship. Because the best documented relationship is that
				between hardness and acute toxicity of metals and a log-log relationship fits
				these data, geometric means and natural logarithms of both toxicity and water
				quality are used in the rest of this procedure to illustrate the method. For
				relationships based on other water quality characteristics, such as pH or
				temperature, no transformation or a different transformation might fit the data
				better, and appropriate changes will be made as necessary throughout this
				method.
(BB) Each acute slope is
				evaluated as to whether or not it is meaningful, taking into account the range
				and number of tested values of the water quality characteristic and the degree
				of agreement within and between species. If meaningful slopes are not available
				for at least one (1) fish and one (1) invertebrate, or if the available slopes
				are too dissimilar, or if too few data are available to adequately define the
				relationship between acute toxicity and the water quality characteristic, the
				AAC is calculated using the procedures in item (i).
(CC) Individually, for each species, the
				geometric mean of the available acute values is calculated and then each of the
				acute values for a species is divided by the mean for the species. This
				normalizes the acute values so that the geometric mean of the normalized values
				for each species individually and for any combination of species is one
				(1.0).
(DD) The values of the water
				quality characteristic are similarly normalized for each species
				individually.
(EE) All the
				normalized data are treated as if they were for the same species and a least
				squares regression of all the normalized acute values on the corresponding
				normalized values of the water quality characteristic is performed to obtain
				the pooled acute slope, V.
(FF) For
				each species the geometric mean, W, of the acute toxicity values and the
				geometric mean, X, of the water quality characteristic are calculated. (These
				were calculated in subitems (CC) through (DD).)
(GG) For each species the logarithmic
				intercept, Y, is calculated using the equation:
(HH) For each species calculate the SMAV at Z
				using the equation:
(II) Obtain the
				FAV at Z by using the procedures described in subitems (BB) through (HH),
				replacing "value" with "intercept".
(JJ) The final acute equation is written as:
Where:
V
=
pooled acute slope (from subitem (EE))
A
=
FAV at Z (from subitem (II))
Since V, A, and Z are known, the FAV can be calculated for
				  any selected value of the water quality characteristic.
(KK) The AAC is equal to the FAV/2.
(D) If data are not
				available for at least five (5) North American freshwater genera meeting the
				requirements in clause (B), go to subdivision (2).