The 50 largest wastewater treatment plants in Colorado
Ranked by average flow · 98 MGD combined · 92% of the state's reported flow
Persigo Wastewater Treatment Plant in Grand Junction is the largest publicly owned wastewater treatment plant in Colorado by reported average flow, treating about 10.37 million gallons per day. The 50 plants below treat 98 MGD between them, 92% of the flow reported by all 139 plants in the state, and serve about 1,019,951 people. Every plant links to its profile with permit and compliance data. Treatment technology is shown with a free Klarifi account.
| # | Facility | City | Avg flow (MGD) | Population | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|---|
| 1 | Persigo Wastewater Treatment Plant | Grand Junction | 10.37 | 75,531 | CO0040053 | Dec 2022 | 1 |
| 2 | Greeley WWTP | Greeley | 8.34 | 109,084 | COL040258 | Dec 2030 | 13 |
| 3 | Big Dry Creek WWTP | Westminster | 6.94 | 122,100 | COR901608 | Jun 2029 | 388 |
| 4 | Parker Water + Sanitation District - North Water Reclamation Facility | Parker | 4.83 | 58,804 | COG072642 | Aug 2018 | 80 |
| 5 | Rainbow Park WWTP | Florence | 3.97 | 47,504 | CO0039748 | Feb 2020 | 0 |
| 6 | South Ft. Collins Sanit. Dist. | Fort Collins | 3.52 | 14,153 | CO0020737 | Jan 2018 | 1 |
| 7 | Steamboat Springs WWTP | Steamboat Springs | 3.46 | 26,851 | CO0020834 | Dec 2021 | 34 |
| 8 | St Vrain Sanitation District | City Of Longmont | 3.34 | 52,634 | CO0041700 | Nov 2017 | 4 |
| 9 | Northglenn WWTP | Brighton | 3.11 | 38,973 | CO0036757 | Dec 2024 | 7 |
| 10 | Fort Lupton WWTF | Fort Lupton | 3.02 | 7,974 | CO0021440 | Jun 2023 | 2 |
| 11 | Town Of Windsor Sewarage Treatment Plant | Windsor | 2.58 | 33,311 | CO0020320 | May 2020 | 0 |
| 12 | Lafayette WWTF | Lafayette | 2.39 | 30,377 | COR900828 | Jun 2029 | 0 |
| 13 | Cherokee Metro District Water Reclamation Facility | Colorado Springs | 2.39 | 42,300 | COX048348 | Jul 2023 | 547 |
| 14 | City Of Louisville | Louisville | 2.34 | 21,171 | CO0023078 | Sep 2016 | 2 |
| 15 | Arapahoe County Water And Waste Water Authority | Englewood | 2.23 | 41,512 | COE015000 | Aug 2020 | 0 |
| 16 | Breckenridge Sanitation District | Breckenridge | 2.11 | 5,061 | CO0021539 | Aug 2020 | 0 |
| 17 | San Juan (formerly Vista) WTP | Pagosa Springs | 1.95 | 12,577 | COG081215 | May 2028 | 81 |
| 18 | City Of Trinidad | Trinidad | 1.76 | 8,340 | CO0031232 | Apr 2020 | 0 |
| 19 | Golden City Of | Jefferson County | 1.66 | — | CO0042170 | Sep 2017 | 0 |
| 20 | Hill-N-Park STP | Greeley | 1.58 | 10,733 | CO0047287 | Dec 2023 | 5 |
| 21 | Sterling City Of | Sterling | 1.4 | 13,998 | CO0026247 | Feb 2017 | 9 |
| 22 | Aspen Consolidated Sanitation District | Aspen | 1.39 | 6,995 | CO0026387 | Apr 2031 | 10 |
| 23 | Vail WWTP | Vail | 1.36 | — | CO0021369 | Feb 2026 | 6 |
| 24 | Berthoud Town Of WWTP | Berthoud | 1.36 | 10,512 | CO0046663 | Jul 2020 | 14 |
| 25 | Clifton #2 West WWTP | Clifton | 1.3 | 22,678 | CO0033791 | Mar 2020 | 0 |
| 26 | Delta WWTP | Delta | 1.2 | 10,180 | COR900345 | Jun 2029 | 1 |
| 27 | Woodmen Hills Metro Dist WWTF | Peyton | 1.19 | 18,281 | CO0047091 | Jan 2020 | 0 |
| 28 | Upper Monument Crk Reg WWTF | Colorado Springs | 1.1 | 9,930 | CO0042030 | Apr 2020 | 38 |
| 29 | Craig WWTF | Craig | 1.08 | 9,048 | CO0040037 | Feb 2021 | 0 |
| 30 | Pinery WWTF | Parker | 1.06 | 9,741 | CO0041092 | Oct 2016 | 2 |
| 31 | Telluride Regional WWTF | Telluride | 1.05 | 9,000 | CO0041840 | Nov 2025 | 92 |
| 32 | Harold D Thompson Regional WW Reclamation Facility | Fountain | 1.04 | 3,400 | CO0000005 | Jun 2018 | 4 |
| 33 | Fruita Wastewater Reclamation Facility | Fruita | 0.99 | 13,408 | CO0048854 | Sep 2025 | 2 |
| 34 | Rifle Reg. WW Reclamation Fac. | Rifle | 0.96 | 10,420 | CO0048151 | Mar 2020 | 2 |
| 35 | Iowa Hill Water Reclamation | Breckenridge | 0.89 | 15,000 | CO0045420 | Feb 2024 | 0 |
| 36 | Upper Thompson WWTP | Estes Park | 0.85 | 10,000 | CO0031844 | Sep 2024 | 1 |
| 37 | Southwest WWTF | Cortez | 0.82 | 8,762 | CO0027545 | Jan 2018 | 0 |
| 38 | Stonegate Village Metro Dist | Parker | 0.76 | 9,741 | COE011000 | Aug 2020 | 3 |
| 39 | Las Animas WWTP | Las Animas | 0.72 | 2,290 | CO0040690 | Jan 2026 | 76 |
| 40 | City Of Salida WWTP | Salida | 0.69 | 6,635 | CO0040339 | Nov 2024 | 0 |
| 41 | Gypsum WWTF | Gypsum | 0.64 | 8,078 | COG080991 | May 2025 | 129 |
| 42 | Woodland Park City Of | Woodland Park | 0.61 | — | CO0043214 | Oct 2020 | 1 |
| 43 | Snowmass Water And San Dist | Snowmass Village | 0.6 | 3,090 | CO0023086 | Apr 2020 | 4 |
| 44 | Low Point WWTP | Johnstown | 0.56 | 17,320 | CO0047058 | Apr 2017 | 0 |
| 45 | Estes Park Sanitation District | Estes Park | 0.53 | 5,886 | CO0020290 | Dec 2020 | 19 |
| 46 | Buena Vista Sanitation District WWTF | Buena Vista | 0.5 | 4,213 | CO0045748 | Oct 2020 | 1 |
| 47 | Rocky Ford Sewage Lagoons | Rocky Ford | 0.49 | 3,874 | CO0023850 | Jul 2020 | 64 |
| 48 | Evergreen WWTP | Evergreen | 0.48 | 8,309 | CO0031429 | Mar 2018 | 0 |
| 49 | Black Hawk/central City Sd WWTF | Black Hawk | 0.47 | 1,679 | CO0046761 | Jun 2017 | 4 |
| 50 | Milliken Sanitation District | Milliken | 0.46 | 8,493 | CO0042528 | Jul 2020 | 2 |
Treatment technology for each plant is shown with a free Klarifi account. Create one →
Largest plants 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: WWTP · POTW · MGD · NPDES permit · Filter press · FOG · all terms
Cite this page
Journalists, researchers and educators are welcome to quote these figures. Please credit Klarifi as the source and link to this page.
Klarifi. “Largest wastewater treatment plants in Colorado (2026).” Updated October 26, 2026. https://klarifi.io/facilities/colorado/largestNeed a custom cut of the data for a state, a county or a list of plants? Email info@klarifi.io.