EPA Air · stack tests by county and year

Air-emissions stack tests in Washington County, Pennsylvania, 2025

59Stack 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 Washington County, Pennsylvania 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 Washington County facility page.

Washington County, Pennsylvania, 2025

Air-emissions stack tests in Washington County, other years

Air-emissions stack tests recorded in Washington County, Pennsylvania, 2025

Date	Facility	Kind	Agency
2025-12-17	ETC NORTHEAST PIPELINE/REVOLUTION CRYO PLT	Pass	State
2025-11-19	MCC INTL/MILLER CENT CAST INC/MCDONALD PLT — high-priority violation on file	Pass	State
2025-11-11	COLUMBIA GAS TRANS LLC/REDD FARM COMP STA	Pass	State
2025-11-05	MARKWEST LIBERTY MIDST & RESOURCES/THREE BROTHERS COMP STA	Pass	State
2025-11-04	ROVER PIPELINE LLC/BULGER COMP STA	Pass	State
2025-10-24	DIVERSIFIED PROD LLC/NV 60 WELLPAD	Pass	State
2025-10-17	DIVERSIFIED PROD LLC/NV 34 WELLPAD — high-priority violation on file	Pass	State
2025-10-16	DIVERSIFIED PROD LLC/NINEVEH 58 WELL PAD — high-priority violation on file	Pass	State
2025-10-15	UGI GIBRALTAR GATHERING LLC/GIBRALTAR COMP STA	Pass	State
2025-10-14	EQM GATHERING OPCO LLC/MCINTOSH COMP STA	Pass	State
2025-10-14	EQM GATHERING OPCO LLC/MCINTOSH COMP STA	Pass	State
2025-10-07	JESSOP STEEL LLC/WASHINGTON PLT	Pass	State
2025-10-07	MARKWEST LIBERTY MIDSTREAM RES/DOWN HOME COMPRESSOR STATION	Pass	State
2025-09-29	NATL FUEL SUPPLY CORP/BUFFALO COMP STA	Pass	State
2025-09-24	EQM GATHERING OPCO LLC/BLUE MOON COMP STA	Pass	State
2025-09-23	MARKWEST LIBERTY MIDSTREAM & RESOURCES/GODWIN COMP STA	Pass	State
2025-09-22	EQM GATHERING OPCO LLC/BLUE MOON COMP STA	Pass	State
2025-09-08	MARKWEST LIBERTY MID & RES / HOSKINS BOOSTER COMP STA	Pass	State
2025-09-04	EQT MIDSTREAM COMPANY LLC/DEEMSTON WICKS COMP STA	Pass	State
2025-08-26	EQM GATHERING OPCO LLC/STEELHEAD COMP STA	Pass	State
2025-08-19	CNX MIDSTREAM OPR CO LLC/MOR-44 COMP STA	Pass	State
2025-08-14	MARKWEST LIBERTY MIDSTREAM & RESOURCES/LOWRY COMP STA	Pass	State
2025-08-11	CNX MIDSTREAM OPR CO LLC/NV-57 COMP STA	Pass	State
2025-07-16	ROVER PIPELINE LLC/BULGER COMP STA	Pass	State
2025-07-16	CNX MIDSTREAM OPR CO LLC/NV-57 COMP STA	Pass	State
2025-07-15	MARKWEST LIBERTY MIDSTREAM & RESOURCES/JOHNSTON COMP STA	Pass	State
2025-07-09	EQM GATHERING OPCO LLC/BLUE MOON COMP STA	Pass	State
2025-07-08	EQM GATHERING OPCO LLC/BLUE MOON COMP STA	Pass	State
2025-07-02	FLEXSYS AMER LTD PAR/MONONGAHELA — high-priority violation on file	Pass	State
2025-07-02	COLUMBIA GAS TRANS CORP/DONEGAL COMP STA	Pass	State
2025-06-23	EQT PROD CO/MOJO COMPRESSOR UNIT	Pass	State
2025-06-03	JESSOP STEEL LLC/WASHINGTON PLT	Pass	State
2025-06-03	EQM GATHERING OPCO LLC/PISCES COMP STA	Pass	State
2025-05-12	MARKWEST LIBERTY MIDSTREAM & RESOURCES/REDD COMP STA	Pass	State
2025-05-07	EQM GATHERING OPCO LLC/MAKO COMP STA	Pass	State
2025-04-29	MARKWEST LIBERTY MIDSTREAM/ CARPENTER COMP STA	Pass	State
2025-04-23	EQM GATHERING OPCO LLC/TWILIGHT COMP STA	Pass	State
2025-04-10	MARKWEST LIBERTY MIDSTREAM & RESOURCES/SHAW COMP STA	Pass	State
2025-04-02	MARKWEST LIBERTY MIDSTREAM/DRYER BOOSTER COMP STA	Pass	State
2025-04-02	EQM GATHERING OPCO LLC/KRYPTONITE COMP STA	Pass	State
2025-04-02	EQM GATHERING OPCO LLC/KRYPTONITE COMP STA	Pass	State
2025-04-01	MARKWEST LIBERTY MIDSTREAM/BRIGICH COMP STA	Pass	State
2025-04-01	EQM GATHERING OPCO LLC/KRYPTONITE COMP STA	Pass	State
2025-03-28	MARKWEST LIBERTY MIDSTREAM/SMITH COMP STA	Pass	State
2025-03-25	MARKWEST LIBERTY MIDSTREAM/BAKER COMP STA	Pass	State
2025-03-25	EQT PROD CO/MOJO COMPRESSOR UNIT	Pass	State
2025-03-19	MARKWEST LIBERTY MIDSTREAM & RESOURCES/FULTON BOOSTER STA — high-priority violation on file	Pass	State
2025-02-27	MARKWEST LIBERTY MIDSTREAM & RESOURCES/LOWRY COMP STA	Pass	State
2025-02-26	MARKWEST LIBERTY MIDSTREAM/WELLING COMP STA	Pass	State
2025-02-20	MARKWEST LIBERTY MIDSTREAM & RESOURCES/NANCY STEWART	Pass	State
2025-02-19	MARKWEST LIBERTY MIDST & RESOURCES/THREE BROTHERS COMP STA	Pass	State
2025-02-19	EQM GATHERING OPCO LLC/BLUE MOON COMP STA	Pass	State
2025-02-10	MARKWEST LIBERTY MIDSTREAM/TIMBERLAKE COMP STA	Pass	State
2025-02-03	K PETROLEUM INC/HACKETT COMP STA — high-priority violation on file	Fail	State
2025-01-28	ROVER PIPELINE LLC/BULGER COMP STA	Pass	State
2025-01-27	LOAN ASSET ISSUER LLC/WEST FINLEY 4 WELL PAD	Pass	State
2025-01-17	ENSINGER INC/WASHINGTON	Pass	State
2025-01-10	EQM GATHERING OPCO LLC/BLUE MOON COMP STA	Pass	State
2025-01-07	NATL FUEL SUPPLY CORP/BUFFALO COMP STA	Pass	State

Dates as filed by the agency that recorded the stack test. Figures from EPA’s ICIS-AIR download.

What this page shows

This page covers Clean Air Act facilities in the EPA air register with stack tests in Washington county, PA, in 2025. It lists 59 stack tests recorded in 2025.