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National Pollutant Discharge Elimination System (NPDES)

National Menu of Best Management Practices (BMPs) for Stormwater-Illicit Discharge Detection and Elimination

Disclaimer: The BMP examples and references included on these fact sheets are not intended to be comprehensive. Additionally, the list of BMPs is not all-inclusive, and it does not preclude MS4s from using other technically sound practices.

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 under an 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.

Phase II MS4s are required to develop a program to detect and eliminate these illicit discharges. This primarily includes developing:

  • a storm sewer system map,
  • an ordinance prohibiting illicit discharges,
  • a plan to detect and address these illicit discharges, and
  • an education program on the hazards associated with illicit discharges.

An effective illicit discharge program needs to be both reactive and proactive. The program is reactive in addressing spills and other illicit discharges to the storm drain system that are found. The program must also be proactive in preventing and eliminating illicit discharges through education, training, and enforcement.

Key BMPs and Resources

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BMP Fact Sheets

EPA is updating the following fact sheets. You can request a copy or recommend any changes by filling out and submitting the form at the bottom of the NPDES Contact Us webpage.

The fact sheets describe the BMPs and generally provide applicability, implementation, and effectiveness information to help municipal stormwater and construction site operators comply with the stormwater Phase II requirements.

Developing an IDDE Program

  • Illicit Discharge Detection and Elimination Program Development
  • Reducing the Occurrence of SSOs

Trash and Illegal Dumping

  • Developing a Used Oil Recycling Program
  • Illegal Dumping Control
  • Trash and Debris Management

Decentralized Wastewater

  • Preventing Septic System Failure
  • Sewage from Recreational Activities

Public Reporting

  • Community Hotlines

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