The process for establishing and assuring adequate implementation of new and revised Water Quality Standards, including schedules of compliance under 303(c) of the Clean Water Act

Summary – The state’s Water Quality Standards (WQS) are the basis for its water quality program. Water Quality Standards and technology-based limits form the basis for water quality pollution control permitting. Designated use(s) of the waters, criteria to support that use(s) and general criteria including anti-degradation policies are the infrastructure for the standards. Water Quality Standards for designated uses for all classified water bodies in Missouri set maximum allowable concentrations for 110 chemicals as well as other criteria such as dissolved oxygen. Designated use(s) may be changed based upon use attainability analysis. The state’s Water Quality Standards contain both narrative criteria that apply to all waters and specific criteria adopted from the U.S. Environmental Protection Agency (EPA) for the protection of all aquatic organisms in classified waters. Missouri complies with Section 307(a) and Section 304(a) of the Clean Water Act, adopting numeric criteria for toxic pollutants if the presence of these substances is likely to affect the water body’s use. The anti-degradation requirement for Missouri is built upon EPA minimum requirements to conserve, maintain and protect existing uses and water quality. Variances from the Water Quality Standards provide time-limited alternatives to changing the standard temporarily, based on the assurance that the standards will be attained. The implementation of Water Quality Standards is consistent with the EPA’s desire for an integrated strategy for water quality control. Section 303 of the Clean Water Act includes the requirement that Water Quality Standards be reviewed once for each three-year period. The Water Pollution Control Program completed a review of the standards beginning in 1968 and continuing through 1973, 1977