Anaerobic digesters and biogas: wastewater treatment plants in Oregon
17 plants · 13% of the state · 128 MGD combined
Klarifi identifies 17 publicly owned wastewater treatment plants with anaerobic digesters and biogas in Oregon, 13% of the 127 plants in the state (128 MGD combined). The largest is Willow Lake WWTP in Salem at 42.45 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 Oregon
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Willow Lake WWTP | Salem | 42.45 | ORL026409 | Dec 2030 | 2 |
| 2 | Durham Waste Handling | Tigard | 24.25 | ORL028118 | Dec 2030 | 6 |
| 3 | Medford Rwrf | Central Point | 16.52 | OR0026263 | Jul 2026 | 1 |
| 4 | Gresham WWTP | Portland | 11.55 | OR0026131 | Aug 2026 | 0 |
| 5 | Albany-Millersburg WRF | Albany | 8.27 | OR0028801 | Jan 2031 | 2 |
| 6 | Tryon Creek WWTP | Lake Oswego | 5.22 | OR0026891 | Apr 2029 | 2 |
| 7 | Mcminnville WWTP | Mcminnville | 4.99 | OR0034002 | Dec 2008 | 2 |
| 8 | Grants Pass STP | Grants Pass | 4.92 | OR0028843 | Sep 2014 | 16 |
| 9 | Sweet Home STP | Sweet Home | 1.88 | OR0020346 | Mar 2010 | 27 |
| 10 | Ashland WWTP | Ashland | 1.67 | OR0026255 | Jan 2027 | 13 |
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 Oregon
Anaerobic digesters and biogas in other states
Anaerobic digesters and biogas in Oregon: 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 October 26, 2026.
Wastewater terms: Anaerobic digester · Biosolids · Sludge dewatering · Centrate · Equalization tank · Ozonation · all terms