Lagoon systems: wastewater treatment plants in Massachusetts
10 plants · 15% of the state · 5 MGD combined
Klarifi identifies 10 publicly owned wastewater treatment plants with lagoon systems in Massachusetts, 15% of the 66 plants in the state (5 MGD combined). The largest is Erving Wastewater Treatment Plant #2 in Erving at 1.72 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 Massachusetts
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Erving Wastewater Treatment Plant #2 | Erving | 1.72 | MA0101052 | Nov 2026 | 36 |
| 2 | Plymouth Wastewater Treatment Facility | Plymouth | 1.31 | MAG590040 | Oct 2027 | 5 |
| 3 | Concord Wastewater Treatment Facility | Concord | 0.68 | MAG590030 | Oct 2027 | 5 |
| 4 | Salisbury Wastewater Treatment Facility | Salisbury | 0.59 | MA0102873 | Jan 2021 | 16 |
| 5 | Ipswich Wastewater Treatment Plant | Ipswich | 0.5 | MAG590036 | Oct 2027 | 2 |
| 6 | Templeton W W T P | Templeton | 0.2 | MAG580038 | Nov 2026 | 19 |
| 7 | Oxford Rochdale Wastewater Treatment Plant | North Oxford | 0.17 | MAG580026 | Nov 2026 | 0 |
| 8 | Leo L. Dubois WPCF - Bridgewater Correction Complex | Bridgewater | 0.15 | MAG580040 | Nov 2026 | 40 |
| 9 | Marion Wastewater Treatment Facility | Marion | 0.09 | MA0100030 | Nov 2022 | 17 |
| 10 | Leicester Water Supply WWTF | Leicester | 0.09 | MAG580027 | Nov 2026 | 5 |
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 Massachusetts
Lagoon systems in other states
Lagoon systems in Massachusetts: 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.