EPA Air · stack tests by state, industry and year

Utilities (NAICS 2211): stack tests in Montana, 2026

31Stack tests

A stack test measures what a source actually emits, at the stack, against the limit in its permit. Each row is one stack test recorded during 2026 at a Montana source whose primary industry code is NAICS 2211. A facility filing more than one industry code is counted under the first one on its record.

Utilities (NAICS 2211) in Montana, other years

Other industries in Montana, 2026

Air-emissions stack tests recorded in Montana, 2026

Date	Facility	Where	Kind	Agency
2026-05-21	COLSTRIP STEAM ELECTRIC STATION	COLSTRIP, Rosebud, MT	Pass	State
2026-05-21	COLSTRIP STEAM ELECTRIC STATION	COLSTRIP, Rosebud, MT	Pass	State
2026-05-18	YELLOWSTONE POWER PLANT — high-priority violation on file	BILLINGS, Yellowstone, MT	Pass	State
2026-05-07	YELLOWSTONE POWER PLANT — high-priority violation on file	BILLINGS, Yellowstone, MT	Pass	State
2026-04-09	COLSTRIP STEAM ELECTRIC STATION	COLSTRIP, Rosebud, MT	Pass	State
2026-04-09	COLSTRIP STEAM ELECTRIC STATION	COLSTRIP, Rosebud, MT	Pass	State
2026-04-09	COLSTRIP STEAM ELECTRIC STATION	COLSTRIP, Rosebud, MT	Pass	State
2026-04-09	COLSTRIP STEAM ELECTRIC STATION	COLSTRIP, Rosebud, MT	Pass	State
2026-04-08	COLSTRIP STEAM ELECTRIC STATION	COLSTRIP, Rosebud, MT	Pass	State
2026-04-08	COLSTRIP STEAM ELECTRIC STATION	COLSTRIP, Rosebud, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-03-13	BASIN CREEK POWER SERVICES	BUTTE, Silver Bow, MT	Pass	State
2026-01-29	COLSTRIP STEAM ELECTRIC STATION	COLSTRIP, Rosebud, MT	Pass	State
2026-01-27	DAVE GATES GENERATING STATION AT MILL CREEK	ANACONDA, Deer Lodge, MT	Pass	State
2026-01-27	DAVE GATES GENERATING STATION AT MILL CREEK	ANACONDA, Deer Lodge, MT	Pass	State
2026-01-27	DAVE GATES GENERATING STATION AT MILL CREEK	ANACONDA, Deer Lodge, MT	Pass	State
2026-01-27	DAVE GATES GENERATING STATION AT MILL CREEK	ANACONDA, Deer Lodge, MT	Pass	State
2026-01-27	DAVE GATES GENERATING STATION AT MILL CREEK	ANACONDA, Deer Lodge, MT	Pass	State
2026-01-27	DAVE GATES GENERATING STATION AT MILL CREEK	ANACONDA, Deer Lodge, MT	Pass	State
2026-01-27	DAVE GATES GENERATING STATION AT MILL CREEK	ANACONDA, Deer Lodge, MT	Pass	State
2026-01-13	COLSTRIP ENERGY LTD PARTNERSHIP	COLSTRIP, Rosebud, MT	Pass	State
2026-01-13	COLSTRIP ENERGY LTD PARTNERSHIP	COLSTRIP, Rosebud, MT	Pass	State
2026-01-13	COLSTRIP ENERGY LTD PARTNERSHIP	COLSTRIP, Rosebud, MT	Pass	State

Primary NAICS code as filed on the facility record; dates as filed by the agency that recorded the stack test. Figures from EPA’s ICIS-AIR download.