Montana wastewater permits expiring in 2028
5 NPDES permits · 21 MGD combined average flow
5 publicly owned wastewater treatment plants in Montana hold NPDES permits that expire during 2028, issued by Montana 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) |
|---|---|---|---|---|---|---|
| City Of Billings Wastewater Treatment Plant | Billings | 20.31 | MTR000459 | Jan 2028 | Clarifiers, Uncovered lagoons, Biogas silos | 7 |
| Libby WWTP | Libby | 0.23 | MTR000752 | Jan 2028 | Carrousels / oxidation ditches, Biogas balloons | 34 |
| Town Of Chester WWTF | Chester | — | MT0020338 | Feb 2028 | Uncovered lagoons | 13 |
| Town Of Columbus - Waste Water Treatment Facility | Columbus | 0.14 | MT0031801 | Oct 2028 | Aerated lagoons | 24 |
| Lodge Grass, Town Of WWTF | Lodge Grass | — | MT0021890 | Dec 2028 | Aerated lagoons, Uncovered lagoons | 56 |
Montana permit renewals in 2028: 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.