Impaired Waters

Under Code of Federal Regulations 40 C.F.R. 130.7, states are required to submit to the U.S. Environmental Protection Agency (EPA), a written methodology document describing the states approach in considering and evaluating existing readily available data and information used to develop its 303(d) list of impaired waterbodies. The department invites the public to review and submit written comments on the draft listing methodology document, before submitting it to the Missouri Clean Water Commission for approval. While EPA does not approve or disapprove the listing methodology document, the department must provide the methodology used during its review of the state’s 303(d) impaired waters list and its determination to list or not to list waters. 

Under 40 C.F.R. 130.7, each state is also required to report the status of their impaired and threatened waters still needing a Total Maximum Daily Load by April 1 of every even-numbered year. Following approval by the Missouri Clean Water Commission, the Section 303(d) list, the 305(b) report and the assessment data on the remaining waters of the state is submitted to EPA as part of Missouri's Section 305(b) Integrated Water Quality Report.

Notice

NEW The department currently is preparing for the 2024-2026 Integrated Water Quality Monitoring and Assessment Report, also known as the 305(b) report and the 303(d) list. The department is requesting readily available and qualified water quality data collected through Oct. 31, 2024. For more information, please review the Request for Water Quality Data.