Illicit Discharge Detection & Elimination

What is an Illicit Discharge?

Illicit discharges are any discharges that go into the storm sewer system that are not composed entirely of stormwater, with some exceptions. Some examples of illicit discharges:

  • Dewatering of sediment-laden water from construction sites
  • Improper washing of equipment, vehicles, or other maintenance activities
  • Improper connection of sanitary sewers
  • Dumping or spilling of paint, household cleaners and chemicals, yard waste, fertilizer, oil and other hazardous materials in or near the storm drain

These discharges are considered ‘illicit’ because public stormwater systems are not designed to accept non-stormwater wastes. Stormwater systems do not treat stormwater in the same way that sanitary sewage or waste water is treated. These wastes are treated at a wastewater treatment plant to achieve a legally specific water quality standard before being discharged to our surface waters.


City Code makes exceptions for activities such as water line flushing and other potable water sources, landscape irrigation, foundation or footing drains, firefighting activities, and any other water source not containing pollutants.

To Report an Illicit Discharge

If there is an immediate threat to human health or safety, call 911 first. 

  • Contact the Minnesota Duty Officer at 651-649-5451 or 1-800-422-0798 
  • Krista Spreiter, Natural Resources Coordinator 
    Email Krista Spreiter
    Office Phone:  651-255-1123 
    Fax:  651-452-8940
  • Mendota Heights Police Department
    Phone: 651-452-1366

Additional Information

For more information on Illicit Discharges, and how you can prevent stormwater pollution: