Stormwater Management: Elmhurst vs Naperville

When does my project in DuPage County need a stormwater permit?

Under the DuPage County Countywide Stormwater and Floodplain Ordinance (DuPage County Code Ch. 15), a stormwater permit is required for development that disturbs land or alters drainage, and on-site detention is required when the project adds 25,000 square feet or more of net new impervious area. Any work within the regulatory floodplain, an Isolated Water of DuPage County, or another wetland also requires a permit regardless of impervious threshold. Permits are issued by DuPage County Stormwater Management or by a DCSM-certified municipality.

What is the release rate for stormwater detention in DuPage County?

The maximum allowable release rate from a detention facility is 0.10 cubic feet per second per acre of disturbed area, evaluated against the pre-development peak discharges for the 2-year, 24-hour and 100-year, 24-hour critical-duration storms using ISWS Bulletin 75 rainfall depths. This release rate applies countywide because the ordinance is adopted under 55 ILCS 5/5-1062 and binds every DuPage municipality.

Does the DuPage stormwater ordinance apply inside cities like Naperville or Wheaton?

Yes. Because 55 ILCS 5/5-1062 authorizes DuPage County to adopt a single countywide stormwater ordinance, the DuPage County Countywide Stormwater and Floodplain Ordinance applies in every one of DuPage's 38 municipalities, not just unincorporated areas. Many municipalities are "certified communities" that issue permits locally, but DuPage County Stormwater Management is the ordinance authority and can enforce countywide.

Who enforces the stormwater ordinance in DuPage County?

DuPage County Stormwater Management (DCSM) enforces the ordinance countywide. Remedies include stop-work orders, permit denial or revocation, civil action in the DuPage County Circuit Court, and orders requiring restoration of floodplain storage or wetlands disturbed without authorization.

What are Naperville's stormwater rules?

Property owners must keep storm sewer inlets clear and never dump debris or chemicals into them. Development projects must comply with both city standards and DuPage County stormwater ordinance.

Where can I discharge my sump pump in Naperville?

Sump pump discharge cannot be directed to sidewalks or streets. It should be directed to your yard where it can be absorbed without flowing onto neighboring properties.