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The County of DuPage
Wheaton, Illinois

Illicit Discharge Detection and Elimination

The  Illinois Environmental Protection Agency (IEPA) General NPDES Permit No. ILR40 requires DuPage County to develop, implement and enforce a program to detect and eliminate illicit discharges in the municipal separate storm sewer system (MS4). As part of this IDDE program, the County is required to effectively prohibit, through ordinance, or other regulatory mechanism, non-storm water discharges into the storm sewer system and implement appropriate enforcement procedures and actions, including enforceable requirements for the prompt reporting to the MS4 of all releases, spills and other non-permitted discharges to the separate storm sewer system, and a program to respond to such reports in a timely manner. Examples of common illicit discharges include sewage, industrial and commercial discharges not covered under another NPDES permit, chlorinated pool water, and spilled or dumped liquids, such as oil.

DuPage County Illicit Discharge Detection and Elimination Ordinance

An IDDE Ordinance for the unincorporated areas of DuPage County was adopted by the County Board on May 26, 2009. With the adoption, the IDDE Ordinance was simultaneously included as Section 16 of the County Code and into Appendix F to the DuPage County Stormwater Management Plan.

Illicit Discharge Monitoring

In an attempt to minimize equipment and staff costs associated with duplicate monitoring efforts, DuPage County has partnered with a majority of the municipal and township permit holders within the County to implement illicit discharge monitoring activities. During dry weather conditions, County staff surveys outfalls and monitors those that are actively discharging. Analysis is performed on the discharged water for a variety of parameters to determine if the flow consists of stormwater or runoff from one of the 21 allowed uses, as stated in ILR40. The monitoring plan anticipates that all of the outfalls discharging into DuPage County's waterways included in the 1:100,000 scale of the National Hydrography Dataset (NHD) will be monitored during the five-year permit cycle. You can view a  map detailing the monitoring cycle.

Suspected Illicit Discharge

In a neighborhood or at a commercial site, look for pipes in disrepair or hoses that lead to a storm drain or body of water. Watch for stains, suds, unusual odors, structural damage to streets or gutters, and abnormal vegetative growth in nearby lakes and streams. Sump pumps, irrigation water, and certain other non-stormwater discharges are not illicit. On or near the water, the most obvious way to spot an illicit discharge is during dry weather. Since storm sewer systems exist to carry stormwater runoff, they are generally active during rain events. Without the presence of rain, water flowing from stormwater outfalls or along swales may carry with it bad news. Some key things to look for are: heavy foam, gray or discolored water, odors (sewage, chlorine, rotten eggs, detergent, chemical, petroleum), oily sheen, trash or unnatural debris, stained pipe, sediment rocks or vegetation and algae growth at or near the outlet. For more information on how to spot an illicit discharge, please review our brochures, A Citizens Guide to Monitoring Stormwater and More Than Rain Down the Drain.

To report a suspected illicit discharge into a municipal separate storm sewer system within DuPage County, please contact the Illicit Discharge Hotline at 630-407-6800 or by email. Please  provide information regarding the outfall location, the type of discharge observed, approximate time of the discharge and contact information if you wish to receive a follow-up.