The 45 largest wastewater treatment plants in Wyoming
Ranked by average flow · 33 MGD combined · 100% of the state's reported flow
Sam H. Hobbs Regional WW Facility (prev. Casper Wwtf) in Casper is the largest publicly owned wastewater treatment plant in Wyoming by reported average flow, treating about 6.6 million gallons per day. The 45 plants below treat 33 MGD between them, 100% of the flow reported by all 58 plants in the state. 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 | Sam H. Hobbs Regional WW Facility (prev. Casper Wwtf) | Casper | 6.6 | — | WY0021920 | Oct 2030 | 14 |
| 2 | Dry Creek Water Reclamation Facility | Cheyenne | 5.48 | — | WY0022934 | Oct 2028 | 1 |
| 3 | Gillette WWTF | Gillette | 2.88 | — | WY0020125 | Jul 2027 | 7 |
| 4 | Sheridan Wastewater Treatment | Sheridan | 2.11 | — | WY0020010 | Nov 2028 | 1 |
| 5 | Rock Springs Water Reclamation Facility | Rock Springs | 1.98 | — | WY0022357 | Mar 2029 | 19 |
| 6 | Jackson Wastewater Lagoon | Jackson | 1.93 | — | WY0021458 | Oct 2029 | 3 |
| 7 | Powell, City Of | Powell | 1.67 | — | WY0020648 | Apr 2028 | 7 |
| 8 | Lander Wastewater Lagoon | Lander | 1.11 | — | WY0020389 | Apr 2026 | 47 |
| 9 | Evanston WWTF | Evanston | 1.01 | — | WY0020095 | Aug 2029 | 0 |
| 10 | City Of Rawlins Wastewater Treatment Facility | Rawlins | 0.85 | — | WY0020427 | Apr 2026 | 6 |
| 11 | Worland Wastewater Lagoon | Worland | 0.76 | — | WY0020176 | Apr 2027 | 0 |
| 12 | Buffalo WWTP | Buffalo | 0.75 | — | WY0021024 | Oct 2026 | 0 |
| 13 | Green River Wastewater Treatment Plant | Green River | 0.66 | — | WY0020443 | Jun 2031 | 13 |
| 14 | Basin Wastewater Lagoon | Basin | 0.58 | — | WY0020028 | Dec 2026 | 35 |
| 15 | Cody Wastewater Lagoon | Cody | 0.54 | — | WY0020451 | Jan 2030 | 2 |
| 16 | Marbleton Wastewater Lagoon | Marbleton | 0.46 | — | WY0021997 | Jul 2031 | 155 |
| 17 | Torrington Wastewater Lagoons | Torrington | 0.44 | — | WY0020231 | Jul 2029 | 18 |
| 18 | Douglas Wastewater Lagoon | Douglas | 0.43 | — | WY0020109 | Oct 2030 | 4 |
| 19 | Thermopolis WWTF | Thermopolis | 0.27 | — | WY0020192 | Aug 2030 | 20 |
| 20 | Mountain View Wastewater Lagoon | Mountain View | 0.25 | — | WY0022896 | Apr 2030 | 50 |
| 21 | Kemmerer Wastewater Treatment | Kemmerer | 0.24 | — | WY0020320 | Aug 2028 | 43 |
| 22 | Hudson Wastewater Lagoon | Hudson | 0.22 | — | WY0020664 | Nov 2028 | 6 |
| 23 | Lyman Wastewater Lagoon | Lyman | 0.2 | — | WY0020117 | Sep 2027 | 47 |
| 24 | Town Of Bear River Wastewater Lagoons | Bear River | 0.17 | — | WY0031712 | Sep 2027 | 7 |
| 25 | Glenrock Wastewater Lagoon | Glenrock | 0.17 | — | WY0020630 | Jun 2030 | 40 |
| 26 | Chief Washakie Recreation Comp | Fort Washakie | 0.16 | — | WYG589101 | Mar 2027 | 77 |
| 27 | Saratoga Wastewater Lagoons | Saratoga | 0.16 | — | WY0021491 | Jan 2029 | 20 |
| 28 | Ten Sleep Wastewater Lagoons | Ten Sleep | 0.15 | — | WYG740962 | Jul 2026 | 14 |
| 29 | Thayne Wastewater Lagoon | Thayne | 0.15 | — | WY0025895 | Jun 2025 | 23 |
| 30 | Ranchester Wastewater Lagoons | Ranchester | 0.12 | — | WY0022161 | Sep 2030 | 13 |
| 31 | Big Piney Wastewater Lagoon | Big Piney | 0.1 | — | WY0020133 | Mar 2028 | 13 |
| 32 | Wright Wastewater Treatment | Wright | 0.09 | — | WY0025992 | Mar 2031 | 0 |
| 33 | Baggs Wastewater Lagoons | Baggs | 0.08 | — | WY0022888 | Jan 2031 | 591 |
| 34 | Byron Wastewater Lagoon | Byron | 0.08 | — | WY0020281 | Mar 2029 | 96 |
| 35 | Greybull Wastewater Lagoon | Greybull | 0.07 | — | WY0020583 | Jun 2027 | 284 |
| 36 | Dubois Wastewater Lagoon | Dubois | 0.06 | — | WY0020834 | Mar 2029 | 27 |
| 37 | Upton Wastewater Lagoon | Upton | 0.05 | — | WY0020605 | Dec 2029 | 5 |
| 38 | Cokeville Wastewater Treatment Plant | Cokeville | 0.05 | — | WY0021032 | Dec 2030 | 108 |
| 39 | Encampment Wastewater Lagoon | Encampment | 0.04 | — | WY0020591 | Dec 2026 | 10 |
| 40 | Town Of Dixon Wastewater Treatment Lagoon | Dixon | 0.03 | — | WY0021938 | Jun 2030 | 247 |
| 41 | Manderson Sewer Project | Manderson | 0.02 | — | WY0052442 | Jan 2029 | 76 |
| 42 | Ethete Water Treatment Plant | Ethete | 0.01 | — | WYDW0002I | Jun 2024 | 125 |
| 43 | Hartville Wastewater Treatment | Hartville | 0.01 | — | WY0021440 | Jun 2025 | 0 |
| 44 | Moorcroft Wastewater Lagoon | Moorcroft | 0.0086 | — | WY0021741 | Jan 2031 | 29 |
| 45 | Riverside Waste Water Treatment Facility | Casper | 0.0048 | — | WY0032662 | Jun 2024 | 41 |
Treatment technology for each plant is shown with a free Klarifi account. Create one →
Largest plants in Wyoming: 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. “The 45 largest wastewater treatment plants in Wyoming (2026).” Updated October 26, 2026. https://klarifi.io/facilities/wyoming/largestNeed a custom cut of the data for a state, a county or a list of plants? Email info@klarifi.io.