Illinois NPDES permit search
Status, expiry and violations for 666 municipal wastewater permits · issued by IEPA
In short
How do I look up an NPDES permit in Illinois?
Search this page by permit number or plant name for a municipal plant’s permit status, expiry date and violations. For the official file, search Illinois EPA’s Document Explorer or Illinois EPA’s DMR search. EPA’s ECHO database shows the monitoring results and violations of every permit. The 3,381 industrial permits in Illinois are listed in Klarifi with a free account.
Links to official sources checked September 2026.
Effective
648
Administratively continued
17
Expired
1
Plants with effluent violations, 3 years
490
Where to find official Illinois NPDES records
Illinois Environmental Protection Agency (IEPA) runs the NPDES program in Illinois under authorization from EPA Region 5. It issues and enforces the permits and keeps the official file: applications, permits, fact sheets and monitoring reports. IEPA website ↗
permit documents · enforcement
Open Attribute Search, type part of the facility name (and a city or county) and open the site for its scanned documents by type, NPDES permits included.
DMRs
Search by NPDES ID or permit name and a monitoring year for the discharge monitoring data; results can be exported.
permit documents
Search the table by NPDES number, facility or county and open the notice for the draft permit.
permits · DMRs · inspections · violations · enforcement
EPA’s Enforcement and Compliance History Online. Search water facilities by permit number, name or city; the Detailed Facility Report lists inspections, violations and enforcement actions, and Effluent Charts plot monitoring results against the permit limits.
- Permit numbers
- Permits follow EPA’s format (IL0020788); Document Explorer also indexes sites by an Illinois EPA Bureau ID.
- Discharge monitoring reports
- Through EPA’s NetDMR.
- Violations and enforcement
- Illinois EPA’s enforcement orders since 2002 ↗
Industrial and commercial NPDES permits in Illinois
Most NPDES permits are not held by municipal plants. EPA’s permit database lists 3,381 individual permits in force for industrial and commercial facilities in Illinois (manufacturers, food processors, mines, power plants, landfills), 139 of them major dischargers, plus 1,780 facilities covered by a general permit, mostly for stormwater. 543 of the individual permits recorded at least one effluent violation in the last three years.
| Facility | Permit | Status | Expires | Effluent violations |
|---|
Unlock 3,381 industrial permits in Illinois
Search every industrial and commercial discharger in Illinois by name or permit number, with permit status, expiry and violation history. Free with a Klarifi account.
Industrial and commercial NPDES permits in Illinois: permits in force (effective or administratively continued) held by facilities EPA does not class as publicly owned treatment works or federal facilities. Source: EPA ICIS-NPDES via Klarifi, October 2026.
Violations at Illinois wastewater plants
490 of the 666 municipal plants on this page recorded at least one effluent violation, a monitored value above a permit limit, in the last three years, and 524 had a violation of any kind, including late or missing monitoring reports. Each plant’s page shows its own count. EPA’s enforcement records list 48 formal cases naming Illinois wastewater plants, 16 of them since fiscal year 2020, with $10.1 million in penalties assessed. Enforcement cases in Illinois →
Permit renewals by year
An NPDES permit runs for five years. To keep discharging, a plant must apply for renewal at least 180 days before the expiry date, and the renewed permit usually arrives with tighter effluent limits, new monitoring requirements or a compliance schedule. That is why the year a permit expires is the year a plant starts budgeting for upgrades: nutrient removal, disinfection, capacity or controls.
2029: 80 permits
2030: 152 permits
2031: 37 permits
Largest permit holders in Illinois
| Facility | City | Avg flow (MGD) | Design (MGD) | NPDES permit | Status | Expires | Violations (3y) |
|---|---|---|---|---|---|---|---|
| MWRDGC Terrence J O'Brien Water Reclamation Plant | Skokie | 205.79 | 450 | IL0028088 | Administratively continued | Jul 2022 | 16 |
| Metropolitan Water Reclamation | Chicago | 281.73 | — | ILL028061 | Effective | Dec 2030 | 10 |
| Sanitary District Of Decatur | Decatur | 34.42 | — | ILL028321 | Effective | Dec 2030 | 1 |
| East Moline Wastewater | East Moline | 4.16 | 27.8 | IL0028550 | Effective | Mar 2031 | 2 |
| Rock River Water Reclamation District | Rockford | 23.71 | — | ILL027201 | Effective | Dec 2030 | 10 |
| Springbrook Water Reclamation Center | Naperville | 20.15 | — | ILL034061 | Effective | Dec 2030 | 0 |
| Greater Peoria Sanitary And Sewage District | Peoria | 19.22 | — | ILL021288 | Effective | Dec 2030 | 12 |
| Spring Creek STP | Springfield | 16.41 | — | ILL021989 | Effective | Dec 2030 | 29 |
| Bloomington Normal WRD -West STP | Bloomington | 16.33 | — | ILL027731 | Effective | Dec 2030 | 0 |
| O Fallon STP | O Fallon | 2.57 | 14.6 | IL0021636 | Effective | Mar 2031 | 0 |
Illinois NPDES permits: questions
NPDES permit search in other states
Sources and methodology
Flow, permit and violation figures come from the EPA's ICIS-NPDES discharge monitoring records. Population served comes from the Clean Watersheds Needs Survey 2022. Treatment structures are identified by Klarifi's review of aerial imagery, and capital improvement projects are extracted from published municipal budget documents. Violations are counted over the last three years of monitoring reports.
Data refreshed October 12, 2026.
Wastewater terms: NPDES permit · POTW · Significant industrial user · MGD · Centrate · Ozonation · all terms