Illicit Discharges

Illicit discharges include any substance that is dumped into a stormwater drainage system, river, lake or stream that is not composed entirely of water. Harmful materials that are discharged often cause odors, kill fish and create an overgrowth of vegetation, like algae blooms.

Household Prevention

  1. Never dump anything down a storm drain.

  2. Household wastewater from laundry, showers and dishwashers is handled differently than stormwater at the water treatment facility. All water leaving a home should go through the wastewater treatment system.

  3. Recycle used motor oil. When it rains, stormwater can wash motor oil off streets and into catch basins that drain into rivers and lakes. Call your local recycling center to find a place to dispose of oil properly.

  4. Wash your car on your lawn. This will help prevent dirty water and suds from reaching lakes and streams. The grass will act as a natural filter and get watered at the same time!

  5. Pick up animal waste. When it rains, stormwater washes animal waste from pavement into drains, adding harmful bacteria to our rivers and lakes.

  6. Sweep sidewalks. Don’t hose dirt, trash or chemicals into the street.

How to Recognize Problems

If you spill hazardous materials or see warning signs of an illicit discharge, like oil slicks, suds or foul odors, contact the Wisconsin Department of Natural Resources 24 Hour Spill Hotline at 1-800-943-0003.

Common signs include:

  • Dry Weather Flow: When a storm drain has flow discharging and is has not rained in at least 72 hours, an illicit discharge may be present.

  • Suds: Improperly connected car washes and pipes from washing machines often cause illicit suds in and around storm drains that deplete oxygen levels in water and harm fish. 

  • Sewage: Sewage pollutes rivers and lakes when people have septic tank overflow pipes or improperly dump travel-trailer waste. Signs of sewage include a distinct odor, black staining in pipes, gray water and evidence of sanitary waste, like toilet paper.  

  • Oil and Gas: Recognized as a sheen in the water, oil and gas often enter water bodies as stormwater runoff from gas station spills and oil leaks on pavement. 

Learn more about what you can do in your home, lawn or community

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