EPA Air · stack tests by county and year

Air-emissions stack tests in Washington County, Pennsylvania, 2026

29Stack 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 2026. 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, 2026

Air-emissions stack tests in Washington County, other years

Air-emissions stack tests recorded in Washington County, Pennsylvania, 2026

Date	Facility	Kind	Agency
2026-08-06	EQT MIDSTREAM COMPANY LLC/DEEMSTON WICKS COMP STA	Pass	State
2026-07-13	MARKWEST LIBERTY MIDSTREAM & RESOURCES/JOHNSTON COMP STA	Pass	State
2026-07-01	EQM GATHERING OPCO LLC/BLUE MOON COMP STA	Pass	State
2026-06-24	COLUMBIA GAS TRANS CORP/DONEGAL COMP STA	Pass	State
2026-06-23	MARKWEST LIBERTY MIDSTREAM & RESOURCES/NANCY STEWART	Pass	State
2026-06-17	EQT PROD CO/MOJO COMPRESSOR UNIT	Pass	State
2026-06-16	GOLDEN EAGLE CONST CO/EIGHTY FOUR PLT	Pending	State
2026-06-02	EQM GATHERING OPCO LLC/PISCES COMP STA	Pass	State
2026-05-04	MARKWEST LIBERTY MIDSTREAM & RESOURCES/REDD COMP STA	Pass	State
2026-04-28	MARKWEST LIBERTY MIDSTREAM/ CARPENTER COMP STA	Pass	State
2026-04-22	EQM GATHERING OPCO LLC/TWILIGHT COMP STA	Pass	State
2026-04-16	MARKWEST LIBERTY MIDST & RES/IMPERIAL CIBUS RANCH COMP STA	Pass	State
2026-04-15	MARKWEST LIBERTY MIDST & RES/IMPERIAL CIBUS RANCH COMP STA	Pass	State
2026-04-09	MARKWEST LIBERTY MIDSTREAM & RESOURCES/SHAW COMP STA	Pass	State
2026-04-01	MARKWEST LIBERTY MIDSTREAM/DRYER BOOSTER COMP STA	Pass	State
2026-04-01	EQM GATHERING OPCO LLC/KRYPTONITE COMP STA	Pass	State
2026-03-31	MARKWEST LIBERTY MIDSTREAM/BRIGICH COMP STA	Pass	State
2026-03-31	EQM GATHERING OPCO LLC/KRYPTONITE COMP STA	Pass	State
2026-03-27	MARKWEST LIBERTY MIDSTREAM/SMITH COMP STA	Pass	State
2026-03-24	MARKWEST LIBERTY MIDSTREAM/BAKER COMP STA	Pass	State
2026-03-20	MARKWEST LIBERTY MIDSTREAM & RESOURCES/HARMON CREEK GAS PLT — high-priority violation on file	Pass	State
2026-03-17	MARKWEST LIBERTY MIDSTREAM & RESOURCES/FULTON BOOSTER STA — high-priority violation on file	Pass	State
2026-03-17	MARKWEST LIBERTY MIDST & RESOURCES/THREE BROTHERS COMP STA	Pass	State
2026-02-26	MARKWEST LIBERTY MIDSTREAM & RESOURCES/LOWRY COMP STA	Pass	State
2026-02-24	MARKWEST LIBERTY MIDSTREAM/WELLING COMP STA	Pass	State
2026-02-12	MARKWEST LIBERTY MIDSTREAM & RESOURCES/NANCY STEWART	Pass	State
2026-02-10	K PETROLEUM INC/HACKETT COMP STA — high-priority violation on file	Pass	State
2026-02-09	MARKWEST LIBERTY MIDSTREAM/TIMBERLAKE COMP STA	Pass	State
2026-01-06	PERRYMAN CO/TITANIUM CONVERSION FAC — 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.

What this page shows

This page covers Clean Air Act facilities in the EPA air register with stack tests in Washington county, PA, in 2026. It lists 29 stack tests recorded in 2026.