EPA Air · stack tests by county and year
Air-emissions stack tests in Crook County, Wyoming, 2025
- 4Stack tests
A stack test measures what a source actually emits, at the stack, against the limit in its permit. Each row below is one stack test recorded against a source in Crook County, Wyoming during 2025. A facility can appear several times: this is the year’s record of what happened, not a list of places. The sources themselves are on the Crook County facility page.
Crook County, Wyoming, 2025
Air-emissions stack tests in Crook County, other years
What stands out
- Stack tests in Crook County, Wyoming, fell from 7 in 2023, the previous year on file, to 4 in 2025.
- The county’s file for stack tests holds 7 years of events, from 2018 through 2026.
- Its 4 stack tests rank 15th of the 16 county cells in Wyoming for 2025.
- Its 4 stack tests are 0.3% of the 1,362 the state’s file holds for 2025.
Every line is computed by formula from the state’s stored file; nothing is estimated.
Air-emissions stack tests recorded in Crook County, Wyoming, 2025
| Date | Facility | Kind | Agency |
|---|---|---|---|
| 2025-10-22 | COLONY PLANT (BENTONITE PERFORMANCE MINERALS) | Pass | State |
| 2025-08-13 | COLONY EAST AND WEST PLANTS (AMERICAN COLLOID COMPANY) | Pass | State |
| 2025-08-13 | COLONY EAST AND WEST PLANTS (AMERICAN COLLOID COMPANY) | Pass | State |
| 2025-08-13 | COLONY EAST AND WEST PLANTS (AMERICAN COLLOID COMPANY) | Pass | State |
Dates as filed by the agency that recorded the stack test. Figures from EPA’s ICIS-AIR download.
What this page shows
Clean Air Act facilities in the EPA air register are covered for Crook county, WY, in 2025. Stack tests recorded in 2025: 4.