Illinois wastewater permits expiring in 2026
21 NPDES permits · 5 MGD combined average flow
21 publicly owned wastewater treatment plants in Illinois hold NPDES permits that expire during 2026, issued by Illinois Environmental Protection Agency. The table lists each plant with its permit number, expiry month, average flow, treatment technology and three-year violation count, in order of expiry.
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.
| Facility | City | Avg flow (MGD) | NPDES permit | Expires | Technology | Violations (3y) |
|---|---|---|---|---|---|---|
| Kampsville Stp, Village Of | Kampsville | 0.03 | IL0055832 | Mar 2026 | Uncovered lagoons | 10 |
| Milford Stp, Village Of | Milford | — | IL0023272 | Mar 2026 | Uncovered lagoons | 1 |
| Braidwood Stp, City Of | Braidwood | 0.77 | IL0054992 | May 2026 | Clarifiers, Carrousels / oxidation ditches | 0 |
| Marengo Stp, City Of | Marengo | 0.24 | IL0020729 | May 2026 | Carrousels / oxidation ditches, Biogas balloons | 46 |
| New Lenox-STP #2, Village Of | New Lenox | 0.84 | IL0046264 | Jun 2026 | Clarifiers | 6 |
| Minonk Stw, City Of | Minonk | 0.3 | IL0037818 | Jun 2026 | Aerated lagoons, Uncovered lagoons | 0 |
| Forreston Stw, Village Of | Forreston | 0.08 | IL0022721 | Jun 2026 | Clarifiers, Aerated lagoons, Uncovered lagoons | 0 |
| Nokomis Stp, City Of | Nokomis | 0.08 | IL0020206 | Jun 2026 | Clarifiers, Aerated lagoons, Uncovered lagoons | 98 |
| Warrensburg STP | Warrensburg | 0.03 | IL0034215 | Jun 2026 | Uncovered lagoons | 37 |
| Beecher Stp, Village Of | Beecher | 0.56 | IL0049522 | Jul 2026 | Aerated lagoons, Uncovered lagoons, Carrousels / oxidation ditches, Biogas silos | 0 |
| Polo Stp, City Of | Polo | 0.23 | IL0030449 | Jul 2026 | Uncovered lagoons, Biogas silos | 0 |
| Bradford Stp, Village Of | Bradford | 0.09 | IL0022195 | Jul 2026 | Aerated lagoons, Biogas silos | 34 |
| Big Rock Stp, Village Of | Big Rock | 0.02 | IL0079464 | Jul 2026 | — | 0 |
| Manito Stp, Village Of | Manito | 0.06 | IL0035904 | Sep 2026 | Aerated lagoons | 2 |
| Aqua Illinois - Grant Park STP | Grant Park | 0.05 | IL0050717 | Oct 2026 | Uncovered lagoons | 6 |
| Rushville Stp, City Of | Rushville | 0.31 | IL0021717 | Nov 2026 | Aerated lagoons, Uncovered lagoons | 2 |
| Farmer City Stp, City Of | Farmer City | 0.03 | IL0022462 | Nov 2026 | Clarifiers, Aerated lagoons | 6 |
| Itasca, Village Of - Prospect Avenue WWTP | Itasca | 0.9 | IL0079073 | Dec 2026 | Aerated lagoons | 5 |
| De Pue | Depue | 0.2 | IL0023523 | Dec 2026 | — | 24 |
| Royal Lakes Stp, Village Of | Royal Lakes | 0.00006 | IL0071391 | Dec 2026 | Uncovered lagoons | 22 |
| Ohlman STP | Ohlman | — | IL0032671 | Dec 2026 | Uncovered lagoons | 0 |
Illinois permit renewals in 2026: questions
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 September 11, 2026.