The 41 largest wastewater treatment plants in Wyoming
Ranked by average flow · 42 MGD combined · 100% of the state's reported flow
Pine Bluffs Wastewater Lagoon in Pine Bluffs is the largest publicly owned wastewater treatment plant in Wyoming by reported average flow, treating about 10 million gallons per day. The 41 plants below treat 42 MGD between them, 100% of the flow reported by all 56 plants in the state. Every plant links to its profile with permit, technology and compliance data.
| # | Facility | City | Avg flow (MGD) | Population | NPDES permit | Expires | Technology | Violations (3y) |
|---|---|---|---|---|---|---|---|---|
| 1 | Pine Bluffs Wastewater Lagoon | Pine Bluffs | 10 | — | WY0032212 | Apr 2029 | Uncovered lagoons | 273 |
| 2 | Sam H. Hobbs Regional WW Facility (prev. Casper Wwtf) | Casper | 6.67 | — | WY0021920 | Oct 2030 | Clarifiers, Uncovered lagoons, Biogas silos | 13 |
| 3 | Dry Creek Water Reclamation Facility | Cheyenne | 4.8 | — | WY0022934 | Oct 2028 | Clarifiers, Biogas silos | 1 |
| 4 | Gillette WWTF | Gillette | 2.92 | — | WY0020125 | Jul 2027 | Clarifiers, Uncovered lagoons, Biogas silos, Biogas balloons | 7 |
| 5 | Sheridan Wastewater Treatment | Sheridan | 2.21 | — | WY0020010 | Nov 2028 | — | 1 |
| 6 | Powell, City Of | Powell | 2.09 | — | WY0020648 | Apr 2028 | — | 7 |
| 7 | Rock Springs Water Reclamation Facility | Rock Springs | 2 | — | WY0022357 | Mar 2029 | Clarifiers, Carrousels / oxidation ditches, Biogas silos, Biogas balloons | 19 |
| 8 | Jackson Wastewater Lagoon | Jackson | 1.94 | — | WY0021458 | Oct 2029 | Aerated lagoons, Uncovered lagoons | 3 |
| 9 | Lander Wastewater Lagoon | Lander | 1.24 | — | WY0020389 | Apr 2026 | Aerated lagoons, Uncovered lagoons | 43 |
| 10 | Evanston WWTF | Evanston | 0.96 | — | WY0020095 | Aug 2029 | Carrousels / oxidation ditches, Biogas balloons | 0 |
| 11 | Buffalo WWTP | Buffalo | 0.79 | — | WY0021024 | Oct 2026 | Uncovered lagoons | 0 |
| 12 | Worland Wastewater Lagoon | Worland | 0.71 | — | WY0020176 | Apr 2027 | — | 0 |
| 13 | Cody Wastewater Lagoon | Cody | 0.6 | — | WY0020451 | Jan 2030 | Aerated lagoons, Covered lagoons | 1 |
| 14 | Basin Wastewater Lagoon | Basin | 0.55 | — | WY0020028 | Dec 2026 | Uncovered lagoons | 38 |
| 15 | Douglas Wastewater Lagoon | Douglas | 0.49 | — | WY0020109 | Oct 2030 | Covered lagoons, Uncovered lagoons | 4 |
| 16 | Torrington Wastewater Lagoons | Torrington | 0.46 | — | WY0020231 | Jul 2029 | Aerated lagoons, Uncovered lagoons | 18 |
| 17 | Lyman Wastewater Lagoon | Lyman | 0.4 | — | WY0020117 | Sep 2027 | Aerated lagoons | 47 |
| 18 | Green River Wastewater Treatment Plant | Green River | 0.37 | — | WY0020443 | Jun 2031 | Aerated lagoons, Uncovered lagoons | 13 |
| 19 | Marbleton Wastewater Lagoon | Marbleton | 0.31 | — | WY0021997 | Mar 2024 | Aerated lagoons, Covered lagoons, Uncovered lagoons | 158 |
| 20 | Thermopolis WWTF | Thermopolis | 0.3 | — | WY0020192 | Aug 2030 | — | 20 |
| 21 | Hudson Wastewater Lagoon | Hudson | 0.25 | — | WY0020664 | Nov 2028 | — | 6 |
| 22 | Kemmerer Wastewater Treatment | Kemmerer | 0.23 | — | WY0020320 | Aug 2028 | Carrousels / oxidation ditches, Biogas balloons | 43 |
| 23 | Moorcroft Wastewater Lagoon | Moorcroft | 0.21 | — | WY0021741 | Jan 2031 | Aerated lagoons, Uncovered lagoons | 28 |
| 24 | Mountain View Wastewater Lagoon | Mountain View | 0.2 | — | WY0022896 | Apr 2030 | Aerated lagoons, Uncovered lagoons | 48 |
| 25 | Hartville Wastewater Treatment | Hartville | 0.14 | — | WY0021440 | Jun 2025 | — | 0 |
| 26 | Big Piney Wastewater Lagoon | Big Piney | 0.14 | — | WY0020133 | Mar 2028 | Uncovered lagoons | 13 |
| 27 | Thayne Wastewater Lagoon | Thayne | 0.14 | — | WY0025895 | Jun 2025 | Aerated lagoons, Uncovered lagoons | 26 |
| 28 | Saratoga Wastewater Lagoons | Saratoga | 0.14 | — | WY0021491 | Jan 2029 | Aerated lagoons, Uncovered lagoons | 20 |
| 29 | Ranchester Wastewater Lagoons | Ranchester | 0.11 | — | WY0022161 | Sep 2030 | Aerated lagoons | 13 |
| 30 | Chief Washakie Recreation Comp | Fort Washakie | 0.1 | — | WYG589101 | Mar 2027 | Aerated lagoons, Uncovered lagoons | 84 |
| 31 | Glenrock Wastewater Lagoon | Glenrock | 0.09 | — | WY0020630 | Jun 2030 | — | 40 |
| 32 | Wright Wastewater Treatment | Wright | 0.09 | — | WY0025992 | Mar 2031 | Aerated lagoons, Uncovered lagoons | 0 |
| 33 | Baggs Wastewater Lagoons | Baggs | 0.08 | — | WY0022888 | Jan 2031 | Aerated lagoons, Uncovered lagoons | 598 |
| 34 | Byron Wastewater Lagoon | Byron | 0.07 | — | WY0020281 | Mar 2029 | Aerated lagoons, Uncovered lagoons | 99 |
| 35 | Dubois Wastewater Lagoon | Dubois | 0.06 | — | WY0020834 | Mar 2029 | Aerated lagoons, Uncovered lagoons | 27 |
| 36 | Encampment Wastewater Lagoon | Encampment | 0.05 | — | WY0020591 | Dec 2026 | Aerated lagoons, Uncovered lagoons | 10 |
| 37 | Upton Wastewater Lagoon | Upton | 0.05 | — | WY0020605 | Dec 2029 | Uncovered lagoons | 6 |
| 38 | Town Of Dixon Wastewater Treatment Lagoon | Dixon | 0.04 | — | WY0021938 | Jun 2030 | Aerated lagoons | 247 |
| 39 | Cokeville Wastewater Treatment Plant | Cokeville | 0.04 | — | WY0021032 | Dec 2030 | Aerated lagoons, Uncovered lagoons | 108 |
| 40 | Manderson Sewer Project | Manderson | 0.02 | — | WY0052442 | Jan 2029 | — | 80 |
| 41 | Ethete Water Treatment Plant | Ethete | 0.0062 | — | WYDW0002I | Jun 2024 | — | 100 |
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 September 11, 2026.