Illicit Discharge


What is an illicit discharge?
The US Environmental Protection Agency defines it as “any discharge into a storm drain system that is not composed entirely of stormwater”. A stormwater system is designed to manage runoff from rainfall. Anything other than rain – trash, yard debris, oil and grease, pet waste, fertilizers – doesn't belong in the drain!

Why is it important to prevent illicit discharges?
Unlike wastewater, stormwater isn’t treated before it enters our streams and rivers. Anything that the water picks up as it moves across driveways and parking lots makes it into the waterways that we rely on for recreation and drinking water supplies. Illicit discharges can be detrimental to the environment and water quality and can cause serious problems for wildlife.

What is the difference between an illicit discharge and an illicit connection?
An illicit discharge can be indirect (e.g., oil spilled in a parking lot) or direct. An illicit connection is an unauthorized, direct discharge of pollutants into a stormwater system through a pipe or other direct connection. One example is a home or business that has a sanitary sewer line from a toilet or shower connected directly to the stormwater system. These systems should always be separate.

What are some examples of illicit discharges?
These should never enter the stormwater system, either directly or indirectly! The drain is just for rain!

  • Automotive fluids
  • Paint
  • Cooking grease and oils
  • Household cleaners
  • Yard debris (grass clippings, leaves, etc)
  • Pet waste

How do you identify an illicit discharge or connection?
Look for pipes or hoses emptying onto the ground or directly into the stormwater system. Nearby streams and rivers may be cloudy or discolored or have an oily or soapy sheen on the surface. They may also have a foul odor or excessive algae growth. Because stormwater systems are only meant to carry rainwater, there should be little to no flow through an outfall structure to a river or stream if there has been no recent rain.

REPORT AN ILLICIT DISCHARGE to the City of Duluth Stormwater Division
Contact us at 770.497.5311 or