Activated sludge and clarifiers: wastewater treatment plants in Colorado
29 plants · 21% of the state · 70 MGD reported by 25 plants
Klarifi identifies 29 publicly owned wastewater treatment plants with activated sludge and clarifiers in Colorado, 21% of the 137 plants in the state (70 MGD reported by 25 plants). The largest is Persigo Wastewater Treatment Plant in Grand Junction at 11.4 MGD.
Activated sludge is the standard mechanical process for cities: aeration basins where bacteria consume organic matter, followed by clarifiers that settle the biomass out. These plants are identified by their circular or rectangular clarifiers and by the suspended-growth process code, and they are the main market for blowers, diffusers, clarifier mechanisms and instrumentation.
The largest activated sludge plants in Colorado
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Persigo Wastewater Treatment Plant | Grand Junction | 11.4 | CO0040053 | Dec 2022 | 1 |
| 2 | Greeley WWTP | Greeley | 9.4 | COL040258 | Dec 2030 | 13 |
| 3 | Big Dry Creek WWTP | Westminster | 6.9 | COR901608 | Jun 2029 | 388 |
| 4 | Parker Water + Sanitation District - North Water Reclamation Facility | Parker | 5.1 | COG072642 | Aug 2018 | 75 |
| 5 | Rainbow Park WWTP | Florence | 4.7 | CO0039748 | Feb 2020 | 0 |
| 6 | South Ft. Collins Sanit. Dist. | Fort Collins | 4.23 | CO0020737 | Jan 2018 | 1 |
| 7 | Northglenn WWTP | Brighton | 3.65 | CO0036757 | Dec 2024 | 10 |
| 8 | Lafayette WWTF | Lafayette | 3.03 | COR900828 | Jun 2029 | 0 |
| 9 | Town Of Windsor Sewarage Treatment Plant | Windsor | 2.85 | CO0020320 | May 2020 | 0 |
| 10 | City Of Louisville | Louisville | 2.68 | CO0023078 | Sep 2016 | 3 |
| 11 | Arapahoe County Water And Waste Water Authority | Englewood | 2.53 | COE015000 | Aug 2020 | 0 |
| 12 | Hill-N-Park STP | Greeley | 1.79 | CO0047287 | Dec 2023 | 5 |
| 13 | San Juan (formerly Vista) WTP | Pagosa Springs | 1.63 | COG081215 | May 2028 | 84 |
| 14 | Berthoud Town Of WWTP | Berthoud | 1.61 | CO0046663 | Jul 2020 | 16 |
| 15 | Clifton #2 West WWTP | Clifton | 1.3 | CO0033791 | Mar 2020 | 0 |
| 16 | Craig WWTF | Craig | 1.09 | CO0040037 | Feb 2021 | 0 |
| 17 | Harold D Thompson Regional WW Reclamation Facility | Fountain | 1.08 | CO0000005 | Jun 2018 | 5 |
| 18 | Fruita Wastewater Reclamation Facility | Fruita | 1.07 | CO0048854 | Sep 2025 | 2 |
| 19 | City Of Trinidad | Trinidad | 1.02 | CO0031232 | Apr 2020 | 0 |
| 20 | Upper Thompson WWTP | Estes Park | 0.88 | CO0031844 | Sep 2024 | 1 |
| 21 | Southwest WWTF | Cortez | 0.79 | CO0027545 | Jan 2018 | 0 |
| 22 | City Of Salida WWTP | Salida | 0.78 | CO0040339 | Nov 2024 | 0 |
| 23 | Perry Park Wsd | Larkspur | 0.18 | COG081366 | May 2028 | 0 |
| 24 | Sageport Wastewater Treatment Plant | Larkspur | 0.09 | CO0043044 | Jan 2024 | 11 |
| 25 | Antonito Town Of | Antonito | 0.08 | CO0040975 | Jun 2024 | 68 |
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
Activated sludge and clarifiers in other states
Activated sludge and clarifiers 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 September 11, 2026.