If a pollutant exhibits reasonable potential to exceed WQS, a water quality-based permit limit is required for that pollutant. Background levels used in calculating WLA_A and WLA_C are described in OAC 252:606-6-11 through 14. If a pollutant's background level alone exceeds a criterion, the WLA is set equal to that criterion.

1. (1) Streams. The following applies to streams:
2. (A) WLA_A. Where Q_e is expressed in cfs, Equation L-1 is used to determine WLAA. Where Q_e is expressed in MGD, Equation L-2 is used.
3. (B) WLA_C. Depending on the value of Q*, Equation L-3, L-4, or L-5 is used to determine WLA_C.
4. (2) Lakes. Depending on whether the discharge conveyance is a pipe or canal, Equation L-6 or L-7 is used to determine WLA_C, or WLA_A, if an acute criterion applies, in the absence of a chronic criterion.

Added at 41 Ok Reg, Number 23, effective 9-15-24