Lagoon systems: wastewater treatment plants in Maine
30 plants · 33% of the state · 8 MGD reported by 27 plants
Klarifi identifies 30 publicly owned wastewater treatment plants with lagoon systems in Maine, 33% of the 92 plants in the state (8 MGD reported by 27 plants). The largest is Sanford Wastewater Treatment Facility in Sanford at 1.42 MGD.
Lagoon systems treat wastewater in large earthen ponds over weeks of retention time, with or without mechanical aeration. They serve thousands of small towns because they are cheap to run, but they struggle with ammonia and nutrient limits, fill with sludge over decades and are the plants most often converted or upgraded when a permit is renewed.
The largest lagoons in Maine
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Sanford Wastewater Treatment Facility | Sanford | 1.42 | ME0100617 | Jul 2023 | 4 |
| 2 | Canton Wastewater Treatment Facility | Canton | 0.77 | ME0102067 | Oct 2029 | 4 |
| 3 | Pittsfield Wastewater Treatment Facility | Pittsfield | 0.71 | ME0100528 | Jun 2030 | 20 |
| 4 | Anson Madison Wastewater Treatment Facility | Madison | 0.67 | ME0101389 | Apr 2031 | 2 |
| 5 | Skowhegan Wastewater Treatment Facility | Skowhegan | 0.54 | ME0100625 | Apr 2031 | 90 |
| 6 | Ogunquit Wastewater Treatment Facility | Ogunquit | 0.49 | ME0100986 | Nov 2023 | 8 |
| 7 | Unity Ud WWTF | Unity | 0.47 | ME0101150 | Oct 2022 | 8 |
| 8 | Jackman Wastewater Treatment Facility | Jackman | 0.35 | ME0100978 | Oct 2024 | 0 |
| 9 | Norway Wastewater Treatment Facility | Norway | 0.33 | ME0100455 | Aug 2030 | 0 |
| 10 | Dover-Foxcroft Wastewater Treatment Facility | Dover-Foxcroft | 0.31 | ME0100501 | Feb 2028 | 6 |
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 Maine
Lagoon systems in other states
Lagoon systems in Maine: 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: WWTP · POTW · Biosolids · Anaerobic digester · NPDES permit · all terms