EPA Air · stack tests by county and year
Air-emissions stack tests in Yellowstone County, Montana, 2025
- 52Stack 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 Yellowstone County, Montana 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 Yellowstone County facility page.
Yellowstone County, Montana, 2025
Air-emissions stack tests in Yellowstone County, other years
Air-emissions stack tests recorded in Yellowstone County, Montana, 2025
| Date | Facility | Kind | Agency |
|---|---|---|---|
| 2025-12-12 | WESTERN SUGAR COOPERATIVE — high-priority violation on file | Pass | State |
| 2025-12-12 | WESTERN SUGAR COOPERATIVE — high-priority violation on file | Pass | State |
| 2025-12-04 | BILLINGS REFINERY | Pass | State |
| 2025-12-04 | BILLINGS REFINERY | Pass | State |
| 2025-12-04 | BILLINGS REFINERY | Pass | State |
| 2025-12-04 | BILLINGS REFINERY | Pass | State |
| 2025-12-04 | BILLINGS REFINERY | Pass | State |
| 2025-12-04 | BILLINGS REFINERY | Pass | State |
| 2025-12-04 | BILLINGS REFINERY | Pass | State |
| 2025-11-18 | YELLOWSTONE COUNTY GENERATING STATION | Pass | State |
| 2025-11-13 | BILLINGS REFINERY | Pass | State |
| 2025-10-28 | BILLINGS REFINERY | Pass | State |
| 2025-10-28 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-10-28 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-10-28 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-10-10 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-10-09 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-10-09 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-10-09 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-10-09 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-10-09 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-09-02 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-09-02 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-08-22 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-08-13 | PAR MONTANA BILLINGS REFINERY | Pass | State |
| 2025-08-13 | PAR MONTANA BILLINGS REFINERY | Pass | State |
| 2025-08-08 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-08-08 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-08-08 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-08-06 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-08-06 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-08-06 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-08-06 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-08-06 | PAR MONTANA BILLINGS REFINERY | Pass | State |
| 2025-08-06 | PAR MONTANA BILLINGS REFINERY | Pass | State |
| 2025-08-06 | PAR MONTANA BILLINGS REFINERY | Pass | State |
| 2025-08-06 | PAR MONTANA BILLINGS REFINERY | Pass | State |
| 2025-08-06 | PAR MONTANA BILLINGS REFINERY | Pass | State |
| 2025-08-04 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-07-22 | PAR MONTANA BULK TERMINAL | Pass | State |
| 2025-07-02 | YELLOWSTONE POWER PLANT — high-priority violation on file | Pass | State |
| 2025-05-30 | YELLOWSTONE POWER PLANT — high-priority violation on file | Pass | State |
| 2025-05-01 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-05-01 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-05-01 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-05-01 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-05-01 | CHS INC REFINERY LAUREL | Pass | State |
| 2025-04-25 | YELLOWSTONE POWER PLANT — high-priority violation on file | Pass | State |
| 2025-04-25 | YELLOWSTONE POWER PLANT — high-priority violation on file | Pass | State |
| 2025-01-20 | WESTERN SUGAR COOPERATIVE — high-priority violation on file | Pass | State |
| 2025-01-20 | WESTERN SUGAR COOPERATIVE — high-priority violation on file | Pass | State |
| 2025-01-14 | WESTERN SUGAR COOPERATIVE — high-priority violation on file | Pass | State |
Dates as filed by the agency that recorded the stack test. Figures from EPA’s ICIS-AIR download.