Illicit Discharge Detection & Elimination

What is an illicit discharge?

The storm sewer system is designed to transport storm water to the nearest river, stream, lack, or wetland.  Any waste or pollution that enters the storm sewer system will flow directly to the nearest waterbody without treatment and may cause serious environmental damage.  Any discharge into a storm sewer system, river, stream, or waterbody that is not composed entirely of storm water is called an illicit discharge.

Common Illicit Discharges

  • Commercial car wash wastewater
  • Restaurant cooking oil
  • Gas, oil, paints, cleaners
  • Fertilizer, grass, leaves, pesticides, pet waste, trash
  • Concrete washout and sediment from construction sites
  • Installation of pipes that bypass sanitary connections or septic drain fields that produce a direct discharge to a waterbody

These illicit discharges may be the result of:

  • Dumping them into the storm sewer system.
  • Allowing fertilizers, grasses, leaves, pesticides, and/or pet waste to wash into storm drains.
  • Improperly working and/or designed wastewater treatment systems that produce discharges to the waterbody.

Be Proactive & Report Suspected Illicit Discharges Promptly

  • Report any suspicious discharges using the online Storm Water Illicit Discharge Report Form, or call the Planning & GIS Department at (406) 454-6905.
  • Clean up hazardous spills immediately.
  • Pick up litter and trash near storm drains and in ditches.
  • Clean up pet waste and dispose of it in the trash.
  • Vegetate bare areas to reduce soil erosion.
  • Do not blow leaves, grass clippings, and mulch into the streets.  Instead, sweep them up and dispose of them properly.
  • Recycle oil, antifreeze, and batteries.
  • Bring household products like paint, paint thinners, and solvents to a hazardous waste dump site.