Section 327 IAC 2-1-8.1 - Calculation of criteria for toxic substances; generalAuthority: IC 13-14-8; IC 13-14-9; IC 13-18-3
Affected: IC 13-18-4
Sec. 8.1.
(a) Water quality standards for the state of Indiana indicate that all surface waters at all times and at all places, including the mixing zone, shall be free of substances or combinations of substances that are in amounts sufficient to be acutely toxic to humans, other animals, plants, or aquatic life. Toxic substances include, but are not limited to, those substances identified under Section 307(a) of the Clean Water Act. The allowable concentration of a toxic substance in surface water shall be determined for that substance by the procedures in sections 8.2 through 8.9 of this rule.(b) The use of dissolved metal to set and measure compliance with water quality standards for aquatic life is the recommended approach because dissolved metal more closely approximates the bioavailable fraction of metal in the water column than does total recoverable metal. Reasons for the consideration of total recoverable metals criteria include risk management considerations not covered by evaluation of water column toxicity. The commissioner may, after considering sediment and food chain effects for a particular metal, decide to take a more conservative approach for the metal. This approach could include the expression of aquatic life criteria for the metal in the form of total recoverable metal. If the commissioner determines that it is appropriate to express aquatic life criteria for a particular metal in the form of dissolved metal, the criteria shall be determined as follows: (1) If sufficient toxicological data in the form of dissolved metal are available, these data shall be used in sections 8.2, 8.3, and 8.9 of this rule to derive aquatic life criteria directly in the form of dissolved metal.(2) If sufficient toxicological data in the form of dissolved metal are not available, aquatic life criteria shall be derived in the form of total recoverable metal using the procedures in sections 8.2, 8.3, and 8.9 of this rule and then multiplied by criteria conversion factors approved by the commissioner to express the criteria in the form of dissolved metal.(3) If sufficient toxicological data in the form of dissolved metal are not available and criteria conversion factors for the particular metal have not been approved by the commissioner, aquatic life criteria shall be derived in the form of total recoverable metal using the procedures in sections 8.2, 8.3, and 8.9 of this rule and expressed in the form of total recoverable metal.Water Pollution Control Board; 327 IAC 2-1-8.1; filed Feb 1, 1990, 4:30 p.m.: 13 IR 1033; errata filed Jul 6, 1990, 5:00 p.m.: 13 IR 2003; filed Feb 14, 2005, 10:05 a.m.: 28 IR 2055