TC Energy's Columbia Gas Transmission declared force majeure Thursday after an unexpected mechanical problem on its Mountaineer XPress system forced an immediate pressure drop on a key transmission line between Jackson County and Cabell County, West Virginia. The restriction cut capacity on the affected segment to zero starting with the September 25 cycle, blocking roughly 1.8 billion cubic feet per day of firm service—nearly matching the 1.88 billion cubic feet recently scheduled through that stretch. Mountaineer XPress is a 2.7-billion-cubic-foot-per-day Appalachian pipeline that moves Marcellus and Utica gas toward markets across the Southeast and Gulf Coast.
Natural gas futures spiked on the news. October contracts rose 4.5%, or 13.6 cents, to $3.159 per million British thermal units by 11:00 a.m. Eastern time Thursday, after climbing more than 12% since early Wednesday, according to market snapshots cited in the report. Other quotes later Thursday showed front-month prices between $3.28 and $3.39, with day-over-day gains around 8% to 9%. Henry Hub spot prices heading into the session had been closer to $2.90. The physical problem affects a 164-mile, 36-inch pipeline segment running south through West Virginia into Cabell County. A separate outage declared September 23 by DT Midstream at the West Braxton meter cut another 400,000 dekatherms per day of Appalachian receipts into Columbia's system, with no estimated return date.
The report notes that upstream receipts at Mountaineer XPress entry points had not yet dropped materially Thursday—Sherwood about 714,000 dekatherms per day, Corral about 267,000, Viking about 5,000—but the full restriction should appear in Friday nominations. If the 1.8 billion cubic feet per day can't find alternate routes, producers may need to reroute or shut in wells. The market reaction mirrors a 2020 force majeure on the same pipeline near Leach that cut Appalachian production by more than 2.2 billion cubic feet per day in a single day and lifted NYMEX prices. Criterion Research, quoted in the report, said an update was expected Friday morning. TC Energy has not provided a restoration date.
The outage matters because Mountaineer XPress is a critical takeaway route for Appalachian gas, feeding local distribution companies, industrial customers, power plants, and other pipelines across roughly 10 states through Columbia's 11,900-mile transmission network. A 1.8-billion-cubic-foot-per-day hole in a 2.7-billion-cubic-foot-per-day pipe is large enough to move prices sharply. But late September is shoulder season—heating demand is low and cooling demand is fading—and many generators have dual-fuel capability or firm contracts on multiple pipelines. No utility has reported residential or commercial outages, and no power plant has confirmed a loss of gas supply tied to this event. Whether the outage becomes a consumer problem depends on how quickly gas can be rerouted, how much storage and linepack Columbia can deploy, and how other Appalachian pipelines absorb the displaced volumes.
Mechanical problems on large-diameter transmission lines can be short—a compressor, valve, or regulator issue fixed in days—or they can require pressure cuts, inspections, and federal coordination lasting weeks. Columbia has a recent history of both. The 2023 Line VB rupture in Virginia produced a long force majeure and later federal litigation over how long the company maintained restrictions. The report emphasizes that what matters now is Friday's official update, any capacity posting for the affected segment, whether producers shut in or shift gas to alternative pipelines like Rover or Transco, and whether any utility or generator notices appear. The first day's futures spike captured trader attention, but the next official notice will determine whether the outage is a brief disruption or a sustained supply constraint with real consumer impact.