Water Quality Standards Review

Water quality standards are the foundation for a wide range of programs under the federal Clean Water Act (CWA). The goal for water quality standards is protecting water uses through applying criteria. The department continually works to improve Missouri’s water quality standards to best reflect the most recent science and regulatory obligations extended to Missouri’s waters. For information about variances from the water quality standards, which allow deviation from meeting a water quality-based effluent limit for dischargers for a limited time, visit Water Quality Standards Variances. 

Three-year Review

Section 303(c)(1) of the Clean Water Act and the regulations EPA developed to implement that section, located in Code of Federal Regulations 40 C.F.R. § 131.20, require that states from time to time, but at least once every three years, hold public hearings to review applicable water quality standards and, as appropriate, modify and adopt water quality standards. Any new or revised water quality standards resulting from the standards review are required to be submitted to EPA for review and approval. If EPA has published new or updated Clean Water Act section 304(a) criteria recommendation and the state does not adopt the new or revised water quality criteria during the standards review, the state must explain why when reporting the results of the standards review to EPA.

A stakeholder workgroup provides input and assistance to the department in developing and refining appropriate water quality standards for protecting Missouri’s streams, lakes and wetlands. For meeting information, please review the Water Quality Standards Workgroup webpage.