Water quality standard variance

(a) A water quality standards variance is a time-limited designated use and criterion for a specific pollutant(s) or water quality parameter(s) that reflect the highest attainable condition during the term of the water quality standards variance. All water quality standard variances shall be developed in accordance with and meet the requirements of 40 CFR 131.14, which are hereby, incorporated by reference, and shall be subject to U.S. Environmental Protection Agency review and approval or disapproval. (b) A water quality standard variance may be developed on a discharger specific, reach specific, waterbody specific, or other site-specific basis. The time-limited designated use and criterion associated with the water quality standard variance do not replace the underlying waterbody designated use and criterion. Additionally, all other applicable water quality standards not specifically addressed by the variance remain applicable. A water quality standard variance serves as the applicable water quality standard for implementing Oklahoma Pollutant Discharge Elimination System (OPDES) permit limits and CWA §401 certification for the term of the water quality standard variance. The underlying waterbody designated use and criterion shall remain applicable for all other CWA purposes.