Oxidation ditches: wastewater treatment plants in Massachusetts
6 plants · 9% of the state · 12 MGD combined
Klarifi identifies 6 publicly owned wastewater treatment plants with oxidation ditches in Massachusetts, 9% of the 66 plants in the state (12 MGD combined). The largest is Pittsfield Wastewater Treatment Facility in Pittsfield at 7 MGD.
Oxidation ditches are ring-shaped activated sludge reactors with long retention times, common at plants between 0.5 and 10 MGD. They are recognisable from the air by their looped channels and rely on surface aerators or brush rotors, which are frequent replacement and energy-efficiency projects.
The largest oxidation ditch plants in Massachusetts
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Pittsfield Wastewater Treatment Facility | Pittsfield | 7 | MA0101681 | Oct 2026 | 84 |
| 2 | Westborough Wastewater Treatment Plant | Westborough | 4.17 | MA0100412 | Apr 2027 | 2 |
| 3 | Merrimac Wastewater Treatment Plant | Merrimac | 0.28 | MAG580030 | Nov 2026 | 0 |
| 4 | Leo L. Dubois WPCF - Bridgewater Correction Complex | Bridgewater | 0.15 | MAG580040 | Nov 2026 | 40 |
| 5 | Stockbridge W W T P | Stockbridge | 0.1 | MAG580029 | Nov 2026 | 0 |
| 6 | Russell Wastewater Treatment Facility | Russell | 0.04 | MAG580023 | Nov 2026 | 2 |
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
Oxidation ditches in other states
Oxidation ditches 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.