Oxidation ditches: wastewater treatment plants in Colorado
9 plants · 6% of the state · 14 MGD combined
Klarifi identifies 9 publicly owned wastewater treatment plants with oxidation ditches in Colorado, 6% of the 139 plants in the state (14 MGD combined). The largest is South Ft. Collins Sanit. Dist. in Fort Collins at 3.52 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 Colorado
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | South Ft. Collins Sanit. Dist. | Fort Collins | 3.52 | CO0020737 | Jan 2018 | 1 |
| 2 | Fort Lupton WWTF | Fort Lupton | 3.02 | CO0021440 | Jun 2023 | 2 |
| 3 | San Juan (formerly Vista) WTP | Pagosa Springs | 1.95 | COG081215 | May 2028 | 81 |
| 4 | Clifton #2 West WWTP | Clifton | 1.3 | CO0033791 | Mar 2020 | 0 |
| 5 | Craig WWTF | Craig | 1.08 | CO0040037 | Feb 2021 | 0 |
| 6 | Pinery WWTF | Parker | 1.06 | CO0041092 | Oct 2016 | 2 |
| 7 | Fruita Wastewater Reclamation Facility | Fruita | 0.99 | CO0048854 | Sep 2025 | 2 |
| 8 | Rifle Reg. WW Reclamation Fac. | Rifle | 0.96 | CO0048151 | Mar 2020 | 2 |
| 9 | Southern Ute Indian Tribe | Ignacio | 0.31 | CO0022853 | Dec 2029 | 18 |
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 Colorado
Oxidation ditches in other states
Oxidation ditches in Colorado: 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 · Sludge dewatering · Tertiary treatment · all terms