MS4 Stormwater Permit/Plan

Under the authority of the Federal Clean Water Act and Water Pollution Control Act, the Missouri Department of Natural Resources (MDNR) has regulatory authority to require local government entities, like St. Charles County, to improve or maintain stormwater quality within their boundaries. To accomplish this, the MDNR issues a permit to the County known as the Municipal Separate Storm Sewer System (MS4) Permit (PDF), which allows the discharge of stormwater into waters of the State.

The permit establishes a 5-year plan setting out how the County will help improve the quality of impaired waters of the nation and assure that unimpaired waters remain unimpaired. The County is also required to complete an annual report that updates the status of the county’s progress in implementing its 5-year stormwater plan.

The permit requires the County to address 6 Minimum Control Measures (MCM). The County's 5-year plan to address these 6 MCMs is included in the permit. Information regarding the different County staff positions that have responsibility for each measure and a prioritized schedule to address each measure are also included in the permit.


We would like to hear your comments and suggestions regarding our Stormwater Management Plan or any other thoughts you may have for strategies to protect our waterways from pollution and erosion. Please contact the Development Review Division by email or call 636-949-1814 with any comments or suggestions you may have.