Water Quality Standards

Oklahoma’s Water Quality Standards are a set of rules adopted by Oklahoma in accordance with the federal Clean Water Act, applicable federal regulations, and state pollution control and administrative procedure statutes. Water Quality Standards serve a dual role: they establish water quality benchmarks and provide a basis for the development of water-quality based pollution control programs, including discharge permits, which dictate specific treatment levels required of municipal and industrial wastewater dischargers.

Identification and protection of beneficial uses are vital to Water Quality Standards implementation. Currently recognized beneficial uses for some or all of the waters in Oklahoma include public and private water supply, fish and wildlife propagation, agriculture, hydropower, municipal and industrial process and cooling water, primary body contact recreation (such as swimming), secondary body contact recreation (such as boating or fishing), navigation, and aesthetics. Physical, chemical, and biological data on Oklahoma’s rivers, streams, and lakes obtained primarily through “use attainability analyses” are used to ascertain the condition of individual waters, determine appropriate present and future beneficial uses, and set realistic standards to protect them.

Through assignment of as many beneficial uses as are attainable, Oklahoma’s Water Quality Standards ensure that existing water quality is not unduly impacted. Science-based narrative and numerical criteria imposed in the Water Quality Standards ensure attainment of beneficial uses while limiting waste and pollution of state waters. For water bodies that have quality greater than that required to protect beneficial uses, such as Scenic Rivers, some municipal water supply lakes, and water possessing critical habitat for endangered species, the Water Quality Standards include an anti-degradation policy statement that provides more stringent protection and is designed to keep stream water quality from declining in these areas.

Although all Oklahoma surface water receives broad protection through the Water Quality Standards, explicit protection is afforded to approximately 27,000 stream and river miles and 650,000 lake surface acres. Beneficial uses have also been assigned to all groundwaters of the state that have a mean concentration of Total Dissolved Solids of 10,000 milligrams per liter or less.

The Board also promulgates Water Quality Standards implementation rules. Implementation rules provide a bridge between Water Quality Standards and water quality management by providing consistent application of numeric and narrative criteria. As in development of the Water Quality Standards themselves, an extensive public participation process is utilized to ensure that the state’s water quality management process strikes an appropriate balance between environmental protection and sound public policy.

The Water Quality Standards Implementation rules contain Use Support Assessment Protocols (USAP) for Oklahoma waterbodies. Developed in coordination with all Oklahoma environmental agencies, the USAP establish a consistent and scientific decision methodology for determining whether a waterbody’s beneficial uses are being supported, outlining minimum data requirements for that decision methodology.