Anaerobic digesters and biogas: wastewater treatment plants in Montana
12 plants · 12% of the state · 46 MGD reported by 11 plants
Klarifi identifies 12 publicly owned wastewater treatment plants with anaerobic digesters and biogas in Montana, 12% of the 102 plants in the state (46 MGD reported by 11 plants). The largest is City Of Billings Wastewater Treatment Plant in Billings at 20.31 MGD.
Anaerobic digesters stabilise sludge in sealed heated tanks and produce biogas, visible from the air as digester silos and gas holders. Plants with digesters are typically above 5 MGD and are the buyers of mixing, heating, gas handling, cogeneration and dewatering equipment.
The largest plants with anaerobic digesters in Montana
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | City Of Billings Wastewater Treatment Plant | Billings | 20.31 | MTR000459 | Jan 2028 | 7 |
| 2 | City Of Missoula WWTF No Exposure | Missoula | 7.52 | MT0022594 | Apr 2020 | 7 |
| 3 | City Of Bozeman WWTP | Bozeman | 7.35 | MT0022608 | May 2017 | 0 |
| 4 | City Of Kalispell WWTP | Kalispell | 3.21 | MT0021938 | Jul 2020 | 11 |
| 5 | City Of Helena WWTP | Helena | 3.14 | MT0022641 | Sep 2017 | 37 |
| 6 | Lewistown WWTP | Lewistown | 2.38 | MT0020044 | Aug 2017 | 32 |
| 7 | Water Reclamation Facility | Livingston | 0.69 | MT0020435 | Oct 2021 | 0 |
| 8 | City Of Belgrade- Belgrade Wastewater Treatment Plant | Belgrade | 0.5 | MTX000116 | Sep 2023 | 30 |
| 9 | Choteau Sewage Treatment Ponds | Choteau | 0.25 | MT0020052 | Aug 2026 | 3 |
| 10 | Libby WWTP | Libby | 0.23 | MTR000752 | Jan 2028 | 34 |
| 11 | Stevensville Waste Water Treatment Plant | Stevensville | 0.21 | MT0022713 | May 2024 | 5 |
| 12 | City Of Great Falls WWTP | Great Falls | — | MT0021920 | Aug 2024 | 0 |
Contacts and project signals for every plant on this list
Klarifi adds verified decision-maker contacts, permit limits, discharge monitoring data and the capital projects planned in each city, filterable by technology, size and compliance record.
Other technologies in Montana
Anaerobic digesters and biogas in other states
Anaerobic digesters and biogas in Montana: 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.