Rule 3745-1-44 | Whole effluent toxicity provisions.

• Effective: March 20, 2024
• Promulgated Under: 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/IC₂₅ 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 IC₂₅.

(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
Five Year Review Date: 3/6/2028
Prior Effective Dates: 10/31/1997, 12/30/2002, 6/7/2011, 2/6/2017