ILState-AdministeredSWPPP Requirements in Illinois
Illinois administers NPDES construction stormwater coverage under permit ILR100000 through IEPA. The 1-acre threshold applies statewide. The Chicago metropolitan area is one of the most complex construction stormwater environments in the US — Cook County and the Metropolitan Water Reclamation District (MWRD) impose overlapping requirements. Illinois has a large construction market with high NOI volume processed through IEPA's e-permitting system.
Illinois SWPPP Key Facts
- ✓Permit ILR100000 — statewide NPDES construction general permit
- ✓Chicago metro MS4 complexity: 6-county overlay with MWRD jurisdiction
- ✓IEPA e-permitting mandatory for NOI submission
- ✓$0 NOI fee statewide
- ✓Illinois has one of the highest construction stormwater permit volumes in the Midwest
Administering Agency
- Agency
- Illinois Environmental Protection Agency (IEPA)
- Phone
- 217-782-3362
- Website
- IEPA Stormwater Program
Permit Details
- Permit Name
- Illinois NPDES Construction Site Stormwater Runoff General Permit
- Permit Number
- ILR100000
- Effective Date
- 2014-03-01
- Permit Document
- View Current Permit
SWPPP Thresholds & Triggers
- Acreage Threshold
- 1 acre of land disturbance
Chicago metro MS4 communities (Cook, DuPage, Kane, Lake, McHenry, Will counties) impose additional local stormwater requirements. Projects near Illinois waterways may require IDNR coordination.
Inspection Requirements
- Inspection Frequency
- At least once every 7 days and within 24 hours after a 0.5-inch or greater rain event
- Rain Event Threshold
- 0.5 inches in 24 hours
- Certified Inspector
- Required by state
- Accepted Certifications
- CPESC, CESSWI, IEPA-recognized inspector
IEPA online NOI system (e-permitting) is the required submission method. Large construction market — IEPA processes high NOI volumes.
Penalties & Enforcement
- Max Civil Penalty (Per Day)
- $50,000 per day per violation
- Criminal Penalties
- Class 4 felony for knowing violations; fines up to $50,000/day
IEPA and Illinois Attorney General can pursue enforcement; Chicago metro has active enforcement programs.
Permit Fees
- NOI Filing Fee
- $0
- Other Fees
- Chicago metro MS4 stormwater fees vary by municipality; MWRD may impose additional requirements
How Illinois Differs from Federal Requirements
- ⚠Illinois administers its own ILR100000 permit rather than EPA's federal CGP.
- ⚠MWRD and Chicago-area MS4 requirements add a local layer with no direct federal equivalent.
- ⚠Illinois maximum civil penalty ($50,000/day) exceeds the standard federal CGP penalty ceiling.
SWPPP Tips for Illinois
- ➤In Cook County, contact the MWRD and local MS4 before filing — local ordinances may impose stricter BMP requirements than ILR100000.
- ➤IEPA e-permitting system can have processing delays during peak construction season (spring); submit early.
- ➤Document all SWPPP amendments carefully — Illinois inspectors verify amendment logs during site visits.
Illinois SWPPP FAQs
Does Illinois require a permit for projects under 1 acre?+
No state ILR100000 coverage required under 1 acre unless part of a larger common plan of development. However, Chicago-area MS4 communities may impose local requirements for smaller sites.
What role does MWRD play in construction stormwater in Chicago?+
The Metropolitan Water Reclamation District of Greater Chicago is a regional wastewater and stormwater authority. Projects in its service area may need to comply with MWRD retention/detention standards in addition to ILR100000.
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