Oxidation ditches: wastewater treatment plants in Minnesota
30 plants · 7% of the state · 12 MGD reported by 28 plants
Klarifi identifies 30 publicly owned wastewater treatment plants with oxidation ditches in Minnesota, 7% of the 460 plants in the state (12 MGD reported by 28 plants). The largest is Buffalo WWTP in Buffalo at 1.23 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 | Buffalo WWTP | Buffalo | 1.23 | MNL040649 | Dec 2030 | 1 |
| 2 | Rogers WWTP | Rogers | 1.09 | MN0029629 | Mar 2026 | 5 |
| 3 | Becker WWTP | Becker | 0.91 | MN0025666 | Sep 2029 | 10 |
| 4 | Luverne WWTP | Luverne | 0.79 | MN0020141 | Apr 2030 | 3 |
| 5 | Big Lake WWTP | Big Lake | 0.74 | MN0041076 | Mar 2023 | 0 |
| 6 | Kasson WWTP | Kasson | 0.64 | MN0050725 | Dec 2028 | 0 |
| 7 | Stewartville WWTP | Stewartville | 0.6 | MN0020681 | Nov 2029 | 4 |
| 8 | Whitewater River Regional WWTP | Saint Charles | 0.58 | MN0046868 | Oct 2027 | 13 |
| 9 | Albertville WWTP | Albertville | 0.58 | MN0050954 | May 2024 | 0 |
| 10 | Otsego East WWTP | Rogers | 0.51 | MN0064190 | Jul 2031 | 0 |
| 11 | Spring Valley WWTP | Spring Valley | 0.48 | MN0051934 | Aug 2028 | 18 |
| 12 | Grand Marais | Grand Marais | 0.48 | MN0020010 | Oct 2029 | 18 |
| 13 | Princeton | Princeton | 0.45 | MN0024538 | Feb 2029 | 2 |
| 14 | Belle Plaine WWTP | Belle Plaine | 0.43 | MN0022772 | May 2027 | 30 |
| 15 | North Branch WWTP | North Branch | 0.37 | MN0024350 | Apr 2025 | 0 |
| 16 | Wadena WWTP | Wadena | 0.29 | MN0020672 | Jun 2028 | 1 |
| 17 | Dawson WWTP | Dawson | 0.23 | MN0021881 | Apr 2029 | 12 |
| 18 | Cannon Falls_wwtf | Cannon Falls | 0.22 | MN0022993 | Apr 2029 | 7 |
| 19 | Wabasha WWTP | Wabasha | 0.18 | MN0025143 | Aug 2025 | 0 |
| 20 | Chatfield WWTP | Chatfield | 0.18 | MN0021857 | Jan 2030 | 0 |
| 21 | Lakefield WWTP | Lakefield | 0.17 | MN0020427 | Apr 2030 | 2 |
| 22 | Caledonia WWTP | Caledonia | 0.16 | MN0020231 | Jan 2024 | 18 |
| 23 | Appleton WWTP | Appleton | 0.15 | MN0021890 | Jan 2028 | 15 |
| 24 | Rushford WWTP | Rushford | 0.11 | MN0024678 | Feb 2031 | 1 |
| 25 | Richmond WWTP | Richmond | 0.09 | MN0024597 | Dec 2027 | 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 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 September 11, 2026.