The goal of the federal Clean Water Act, found in U.S. Code 33 U.S.C. §1251 et seq., is "to restore and maintain the chemical, physical, and biological integrity of the Nation's waters." Missouri’s water quality standards establish pollutant limits to protect drinking water supply, fishing, swimming, aquatic life and other designated uses. When waterbodies fail to meet state water quality standards, they are considered impaired waters.
The Clean Water Act requires states to develop total maximum daily loads (TMDLs) for all waters listed on its 303(d) list of impaired waters. TMDLs are tools to inform watershed planning. They calculate the maximum amount of a specific pollutant, or load, a water body can absorb and still meet water quality standards. This calculated loading is then divided between the various pollutant sources in the watershed and becomes the goal, or loading target, to restore water quality.
In Missouri, the Missouri Department of Natural Resources develops TMDLs. Each TMDL document includes load allocations for all pollutant sources. It also includes an implementation plan to identify how the load will be reduced to a level that will protect water quality. The implementation strategies document provides guidance for achieving the TMDL targets and describes ways in which stakeholders in the watershed can reduce pollutant loading to the impaired streams. The plan also identifies potential partnerships and funding sources.
Additional Information
Development Prioritizing and Scheduling
Impaired waters are ranked as high, medium or low priority for TMDL development. For impairments ranked as high priority, a specific year is given for when a TMDL may be developed. All priority rankings and development schedules are reevaluated with each new 303(d) list of impaired waters.
- Prioritization Framework for Development of Total Maximum Daily Loads
- TMDL Alternative - Category 5-alt Components
Impairments identified as high priority in the 2022 Section 303(d) list and as scheduled to begin development in 2022 will be provided to EPA for including in the national bridge metric goals. These are called “bridge metrics” because this is just a temporary metric bridging the gap between the 2013-2022 and the 2024-2034 metrics. Beginning with the 2024 Section 303(d) list, a more formalized national 303(d) framework will be implemented. The Missouri water bodies included in the bridge metrics are identified by an asterisk next to the Water Body Identification Number in the TMDLs Under Development tab.
Under Development
All draft TMDLs are made available for review and comment during a 45-day public comment period. Email public comments or questions about TMDLs to tmdl@dnr.mo.gov.
TMDL Documents Under Development
| HUC 8 | Water Body Identification Number and Name | Pollutant | Comments |
|---|---|---|---|
| 07110009 |
| Chlorophyll-a Aquatic Macroinvertebrate Bioassessment | The draft TMDL and Nine Element Watershed Based Plan documents were available for public review and comment from Jan. 24, 2025 to March 10, 2025. |
| 07140102 |
| E. coli | TMDL under development |
| 07140104 |
| Copper Cadmium Lead Nickel Zinc | The draft TMDL document was available for public review and comment from April 7, 2023 to May 22, 2023. |
| 10280101 |
| Chlorophyll-a | TMDL under development |
| 10290107 |
| E. coli | A second draft TMDL and Nine Element Watershed Based Plan documents was available for public review and comment from Oct. 17, 2025, through Dec. 1, 2025. |
| 10300103 |
| E. coli | A draft TMDL is available for public review and comment from April 10, 2026, through May 25, 2026. For more information, review the Lamine River and Muddy Creek public notice. |
| 10300104 |
| Chlorophyll-a | TMDL under development |
Approved TMDLs
Approved TMDLs are the final TMDL document, as approved by the U.S. Environmental Protection Agency after public notice and comment. Access to final TMDL documents are provided below in two different formats. The only difference is the amount of additional information provided about the impaired water body or lake.
- Missouri Approved or Established Total Maximum Daily Loads - A PDF document containing minimal information about the impaired water body or lake and links to the final TMDL document and implementation document, if available.
- Tools and Resources for Watershed Planning and Improvement - A TMDL identifies water quality problems, possible causes and provides targets for restoration. However, actual water quality improvements are often dependent upon voluntary actions and support from local communities and landowners residing within the watershed.
Contact Information
Water Protection Program
Division of Environmental Quality
P.O. Box 176
Jefferson City, MO 65102-0176
United States
