Illicit discharges are any discharge into a storm drain system this is not composed entirely of stormwater. The exceptions include water from fire fighting activities and discharges from facilities already under an WPDES permit. Illicit discharges are a problem because, unlike wastewater which flows to a wastewater treatment plant, stormwater flows to waterways without any additional treatment. Illicit discharges often include pathogens, nutrients, surfactants, and various toxic pollutants.
As a permitted MS4, the City of Manitowoc has developed a program to detect and eliminate these discharges. The program includes: