Okla. Admin. Code § 252:740-3-2
Current through Vol. 41, No. 19, June 17, 2024
Section 252:740-3-2 - Dilutions for whole effluent toxicity testing(a)General. Generally, two whole effluent toxicity tests shall be used to implement the narrative criteria to protect fish and wildlife propagation. The 48-hour acute test will be used to protect against acute toxicity in receiving water, and the 7-day or 21-day chronic test will be used to protect against chronic toxicity outside the chronic regulatory mixing zone.(b)Differing requirements for WET tests.(1) Three different toxicity testing requirements exist. Each is based upon dilution capacity, represented by Q*.(2) When Q* is less than 0.054, acute testing only shall be required.(3) When Q* is greater than 0.33, chronic testing only shall be required.(4) When Q* is greater than or equal to 0.054 and less than or equal to 0.33, both acute and chronic testing shall be required.(5) For a discharge directly to a lake, acute testing only shall be required.(c)Dilutions for chronic WET tests for streams. Whole effluent chronic toxicity testing requires that test organisms be subjected to various effluent dilutions. The dilution series for chronic toxicity testing is based on the critical dilution (CD). The chronic critical dilution equations are as follows: CD = (1.94Q*)/(1 + Q*) when Q* is less than or equal to 0.1823, or CD = 1/(6.17 - 15.51Q*) when Q* is greater than 0.1823 and less than 0.3333, or CD = 1 when Q* is greater than or equal to 0.3333. Q* = Q e/Q u. Q e is the largest thirty-day average flow for an industrial discharge, if known, and the design flow otherwise. Q u is 1 cfs or the 7Q2 receiving stream flow, if known to be larger.(d)Dilutions for acute WET tests. The acute critical dilution is 100%.Okla. Admin. Code § 252:740-3-2
Adopted by Oklahoma Register, Volume 40, Issue 6, December 1, 2022, eff. 10/25/2022Adopted by Oklahoma Register, Volume 40, Issue 24, September 1, 2023, eff. 9/15/2023