Illicit Discharge Detection & Elimination

Illicit discharges are generally any discharge into a storm drain system that is not composed entirely of stormwater. The exceptions include water from fire fighting activities and discharges from facilities already under an NPDES permit. Illicit discharges are a problem because, unlike wastewater which flows to a wastewater treatment plant, stormwater generally flows to waterways without any additional treatment. Illicit discharges often include pathogens, nutrients, surfactants, and various toxic pollutants.

Phase II MS4 entities are required to develop programs to detect and eliminate illicit discharges. This primarily includes developing:

  • a storm sewer system map,
  • an ordinance prohibiting illicit discharges,
  • enforcement
  • 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 programs are reactive in addressing spills and other illicit discharges to the storm drain system that are found. These programs must also be proactive in preventing and eliminating illicit discharges through education, training and enforcement.


If you observe illegal dumping/illicit discharge or if you see anyone pouring something into a storm drain inlet, ditch or stream, please call the Merrillville Stormwater Utility at (219) 472-8668.

  • This could be along a back property line, along a stream bank, in a woods or in some other off-road area.
  • Another form of illegal dumping involves putting debris or pouring anything other than stormwater runoff into a storm sewer inlet.
  • Debris or waste dumped down a storm sewer inlet causes water pollution and block drainage resulting in potential flooding.
  • Storm sewers outlet directly into lakes, streams and rivers, so anything that goes into a storm drain will end up in a water body.
  • Stormwater runoff from sites where debris is dumped can carry pollutants into the storm sewer system.

Merrillville Stormwater Utility sometimes relies on citizens to report illegal dumping so that it can be cleaned up and water quality can be protected. When you call to report illegal dumping, it is helpful to have the following information:

  • Digital photos or video of any suspicious activity
  • Location of the dumping or discharge
  • Time the incident was observed
  • Description of what was being dumped
  • Vehicle description if a vehicle was involved
  • License plate information
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