• State Standards in Effect for CWA Purposes
• Federally Proposed or Promulgated Standards
• Federal Clean Water Act Determinations that New or Revised Standards Are Necessary

State Standards in Effect for CWA Purposes

• [See Rules of Department of Natural Resources: Division 20- Chapter 7 - 10 CSR 20-7.010 - 10 CSR 20-7.050 (2012) ]
  (Effective December 26, 2019) Water quality standards for waters of the state. Please note that some provisions in this document have not been approved by EPA and are therefore not in effect for CWA purposes.  See the cover page for more information.
• [See Variances to Missouri Surface Water Quality Standards ]
  (Effective February 25, 2015) Information detailing EPA-approved variances from water quality standards for dischargers to Missouri surface waters.

Federally Proposed or Promulgated Standards

• Proposed Nutrient Criteria for Missouri Lakes and Reservoirs (December 2017)

Federal Clean Water Act Determinations that New or Revised Standards Are Necessary

EPA has issued the following determinations under Clean Water Act section 303(c)(4)(B) that new or revised standards are necessary. EPA may propose federal replacement standards in these cases if the state does not adopt standards consistent with the Act.

• Determinations that New Water Quality Standards are Necessary to Protect the Mississippi River for Recreation
  • For segments upstream and downstream of St. Louis
    • [See Determination Letter 12/12/2008 ]
  • For the segment near St. Louis
    • [See Determination Letter 10/29/2009 ]
• Determination that New Water Quality Standards are Necessary to Protect Water Body Segments in the State of Missouri
  • [See Determination Letter ] (10/31/2006)
  • [See EPA's Detailed Analysis ]

Top of Page

• Rules of Department of Natural Resources: Division 20 - Chapter 7 - 10 CSR 20-7.010 - 10 CSR 20-7.050 (2019) (PDF)(135 pp, 5 MB)
• Variances to Missouri Surface Water Quality Standards (PDF)(2 pp, 232 K)
• Determination that WQS are needed for 141 Water Body Segments in the State of Missouri (PDF)(7 pp, 553 K, October 31, 2006)
• EPA’s Detailed Analysis of Whether New or Revised Water Quality Standards are Necessary for 141 Water Body Segments (PDF)(17 pp, 137 K, October 31, 2006)
• Determination that WQS are needed for Mississippi River segments upstream and downstream of St. Louis (PDF)(6 pp, 272 K, December 12, 2008)
• Determination that WQS are needed for the Mississippi River segment near St. Louis (PDF)(10 pp, 182 K, October 29, 2009)