Oxidation ditches: wastewater treatment plants in Minnesota
30 plants · 6% of the state · 13 MGD reported by 27 plants
Klarifi identifies 30 publicly owned wastewater treatment plants with oxidation ditches in Minnesota, 6% of the 470 plants in the state (13 MGD reported by 27 plants). The largest is Whitewater River Regional WWTP in Saint Charles at 2.35 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 Minnesota
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Whitewater River Regional WWTP | Saint Charles | 2.35 | MN0046868 | Oct 2027 | 13 |
| 2 | Rogers WWTP | Rogers | 1.16 | MN0029629 | Mar 2026 | 5 |
| 3 | Buffalo WWTP | Buffalo | 1.08 | MNL040649 | Dec 2030 | 1 |
| 4 | Becker WWTP | Becker | 0.9 | MN0025666 | Sep 2029 | 10 |
| 5 | Luverne WWTP | Luverne | 0.83 | MN0020141 | Apr 2030 | 2 |
| 6 | Big Lake WWTP | Big Lake | 0.73 | MN0041076 | Mar 2023 | 0 |
| 7 | Kasson WWTP | Kasson | 0.63 | MN0050725 | Dec 2028 | 0 |
| 8 | Albertville WWTP | Albertville | 0.56 | MN0050954 | May 2024 | 0 |
| 9 | Stewartville WWTP | Stewartville | 0.54 | MN0020681 | Nov 2029 | 4 |
| 10 | Otsego East WWTP | Rogers | 0.53 | MN0064190 | Jul 2031 | 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 Minnesota
Oxidation ditches in other states
Oxidation ditches in Minnesota: 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: Oxidation ditch · Activated sludge · Biological nutrient removal · NPDES permit · POTW · all terms