Rule 3745-1-44. Whole effluent toxicity provisions

119.03 [Comment: For dates of non-regulatory government publications, publications of recognized organizations and associations, federal rules and federal statutory provisions referenced in this rule, see rule 3745-1-03 of the Administrative Code.] [Comment: See rule 3745-2-09 of the Administrative Code for whole effluent toxicity water quality based effluent limit calculation procedures.] (A) Protection of aquatic life - whole effluent approach. (1) An acute toxicity level of 0.3 acute units (TU a ) applies outside the mixing zone to limited resource water, warmwater, exceptional warmwater, coldwater, seasonal salmonid, and modified warmwater habitat use designations in accordance with this chapter and the following equation: TU a = 100/LC50 Where: LC50 = the median lethal concentration as defined in rule 3745-2-02 of the Administrative Code. (2) A chronic toxicity level of 1.0 chronic toxic units (TU c ) applies outside the mixing zone to warmwater, exceptional warmwater, coldwater, seasonal salmonid, and modified warmwater habitat use designations, where: TU c = 100/IC 25 for all chronic endpoints, except that: TUc = 100/(geometric mean of NOEC and LOEC) for survival or mortality endpoints using daphnid species when this is more restrictive than the TU c value resulting from the definition based on IC 25 . (B) The chronic toxicity level does not apply to limited resource water use designations. (C) For undesignated waters, an acute toxicity level of 0.3 TU a and a chronic toxicity level of 1.0 TU c applies outside of the mixing zone. (D) Acute toxicity within the mixing zone is regulated by paragraph (B) of 3745-33-07 of the Administrative Code. Last updated March 25, 2024 at 10:07 AM Supplemental Information Authorized By: 6111.03 , 6111.041 , 6111.12 Amplifies: 6111.12 3/6/2028 10/31/1997, 2/6/2017