Idaho wastewater permits expiring in 2026
6 NPDES permits · 1 MGD combined average flow
6 publicly owned wastewater treatment plants in Idaho hold NPDES permits that expire during 2026, issued by Idaho Department of Environmental Quality. 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) |
|---|---|---|---|---|---|---|
| White Bird Sewage Treatment System | White Bird | — | ID0024252 | Mar 2026 | Aerated lagoons | 11 |
| Richfield WWTP | Richfield | — | ID0021211 | Apr 2026 | Aerated lagoons, Uncovered lagoons | 19 |
| Salmon Sewage Lagoon | Salmon | 1.02 | ID0020001 | May 2026 | Aerated lagoons, Uncovered lagoons | 0 |
| Cottonwood STP | Cottonwood | — | ID0021849 | Aug 2026 | Uncovered lagoons | 22 |
| Ahsahka Wastewater Treatment Plant | Orofino | 0.02 | ID0025224 | Dec 2026 | — | 0 |
| Riverside Water And Sewer District WWTP | Orofino | — | ID0024503 | Dec 2026 | Aerated lagoons, Uncovered lagoons | 4 |
Idaho 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.