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National Pollutant Discharge Elimination System (NPDES) Permit Program

The NPDES stormwater program regulates some stormwater discharges from three potential sources: municipal separate storm sewer systems (MS4s), construction activities and industrial activities. NPDES permits maybe required before operators of these systems can discharge stormwater. These permits aim to help prevent stormwater from carrying harmful pollutants into surface waters. Additional NPDES information can be found at the EPA's NPDES Stormwater ProgramMinnesota Pollution Control Agency's stormwater, and  Minnesota Pollution Control Agency's MS4 webpages.

Illicit discharge

The City of St. Louis Park is permitted by the Minnesota Pollution Control Agency (MPCA) to discharge stormwater from the city into Minnesota’s streams, lakes or wetlands as a part of the Municipal Separate Storm Sewer System (MS4) permit.

One of the requirements of the MS4 permit is the detection and elimination of illicit discharges, or non stormwater pollutants entering our storm sewer system. Minnesota’s public waters are highly valued resources, sources of drinking water and provide recreational opportunities for all of us, which all can be negatively impacted if pollutants in stormwater runoff.

What is an illicit discharge?

An illicit discharge is any discharge into our storm sewer system that is not comprised entirely of stormwater or is harmful to the health and welfare of our citizens, environment, surface waters or storm sewer system. Illicit discharges would include items such as:

  • Sewage from broken sewer lines
  • Automotive chemicals or other petroleum products
  • Pesticides, herbicides, paint, household cleaners, etc.
  • Sediment and debris from construction sites

Illicit discharges could be an intermittent discharge, which only occurring a few minutes per day or a few days per year; a continuous discharge, occurring routinely; or transitory discharge, which is only a one-time occurrence. 

What activities are not considered illicit discharges?
  • Emergency or firefighting activities
  • Hydrant flushing
  • Residential car washing
  • Draining swimming pools that are de-chlorinated
What do you do if you suspect or witness an illicit discharge?

If you notice storm sewer discharges with unusual odors, floatables, oil film or coloring, the best way to notify the city is by submitting a request through myStLouisPark, search "illicit discharge." By using myStLouisPark, you can provide the following information to the proper city staff:

  • Area of impact
  • Photo documentation of discharge
  • Description of discharge

You can also contact the engineering department to report the problem or call 911 if you suspect the issue needs immediate attention. City staff can evaluate the situation and determine if harmful pollutants are present and define the proper course of action. The city has developed an Illicit Discharge Detection and Response Plan to manage illicit discharges, which is also incorporated into routine inspection and maintenance activities.