Stallings Engineering & Stormwater Logo

Illicit Discharge Information & Reporting

Illicit Discharge Detection and Elimination (IDDE)

What is Illicit Discharge?

In general, illicit discharges include any discharge into a storm drain system that is not entirely composed of stormwater. The exceptions include water from firefighting activities and discharges from facilities already covered under a National Pollutant Discharge Elimination System (NPDES) permit. Illicit discharges are a problem because, unlike wastewater, which flows to a treatment plant, stormwater generally flows to waterways without any additional treatment. Illicit discharges often contain pathogens, nutrients, surfactants, and various toxic pollutants.

Nonpoint Source (NPS) Pollution

NPS pollution generally results from land runoff, precipitation, atmospheric deposition, drainage, seepage or hydrologic modification. NPS pollution, unlike pollution from industrial and sewage treatment plants, comes from many diffuse sources. NPS pollution is caused by rainfall or snowmelt moving over and through the ground. As the runoff moves, it picks up and carries away natural and human-made pollutants, finally depositing them into lakes, rivers, wetlands, coastal waters and ground waters.

Identifying and Preventing Illicit Discharge

Keep litter, pet waste, leaves and debris out of street gutters and storm drains—these outlets drain directly to lake, streams, rivers and wetlands.
Apply lawn and garden chemicals sparingly and according to directions.
Dispose of used oil, antifreeze, paints, and other household chemicals properly—not in storm sewers or drains. If your community does not already have a program for collecting household hazardous wastes, ask your local government to establish one.
Clean up spilled brake fluid, oil, grease and antifreeze. Do not hose them into the street where they can eventually reach local streams and lakes.
Control soil erosion on your property by planting ground cover and stabilizing erosion-prone areas.
Encourage local government officials to develop, amend, and enforce construction erosion and sediment control ordinances in your community.
Have your septic system inspected and pumped, at a minimum every three to five years, so that it operates properly.
Purchase household detergents and cleaners that are low in phosphorus to reduce the amount of nutrients discharged into our lakes, streams and coastal waters.