Lagoon systems: wastewater treatment plants in Colorado
67 plants · 48% of the state · 47 MGD reported by 57 plants
Klarifi identifies 67 publicly owned wastewater treatment plants with lagoon systems in Colorado, 48% of the 139 plants in the state (47 MGD reported by 57 plants). The largest is Persigo Wastewater Treatment Plant in Grand Junction at 10.37 MGD.
Lagoon systems treat wastewater in large earthen ponds over weeks of retention time, with or without mechanical aeration. They serve thousands of small towns because they are cheap to run, but they struggle with ammonia and nutrient limits, fill with sludge over decades and are the plants most often converted or upgraded when a permit is renewed.
The largest lagoons in Colorado
| # | Facility | City | Avg flow (MGD) | NPDES permit | Expires | Violations (3y) |
|---|---|---|---|---|---|---|
| 1 | Persigo Wastewater Treatment Plant | Grand Junction | 10.37 | CO0040053 | Dec 2022 | 1 |
| 2 | Greeley WWTP | Greeley | 8.34 | COL040258 | Dec 2030 | 13 |
| 3 | Steamboat Springs WWTP | Steamboat Springs | 3.46 | CO0020834 | Dec 2021 | 34 |
| 4 | Town Of Windsor Sewarage Treatment Plant | Windsor | 2.58 | CO0020320 | May 2020 | 0 |
| 5 | Cherokee Metro District Water Reclamation Facility | Colorado Springs | 2.39 | COX048348 | Jul 2023 | 547 |
| 6 | Arapahoe County Water And Waste Water Authority | Englewood | 2.23 | COE015000 | Aug 2020 | 0 |
| 7 | City Of Trinidad | Trinidad | 1.76 | CO0031232 | Apr 2020 | 0 |
| 8 | Golden City Of | Jefferson County | 1.66 | CO0042170 | Sep 2017 | 0 |
| 9 | Hill-N-Park STP | Greeley | 1.58 | CO0047287 | Dec 2023 | 5 |
| 10 | Sterling City Of | Sterling | 1.4 | CO0026247 | Feb 2017 | 9 |
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
Lagoon systems in other states
Lagoon systems 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 · Biosolids · Filter press · FOG · all terms