[Transwestern Pipeline] [Capacity Constraint] EAST MAINLINE
SEV 4/5Force Majeure1 days
Summary
Transwestern Pipeline declared force majeure on the East Mainline effective Aug 18 2026 at 9:00 AM through Aug 19 2026 at 8:59 AM -- a roughly 24-hour outage window. The East Mainline carries Permian and San Juan Basin gas westbound toward SoCal and Arizona delivery points. No specific capacity volume is stated in the notice.
Trading note
TW East Mainline force majeure removes westbound Permian/San Juan takeaway capacity for approximately one gas day; expect bearish pressure at Transwestern Permian basis (most recently -0.855 vs HH on 2026-08-17, 5-day average -0.809) and Waha as basin gas backs up, with bullish pressure at SoCal Gas and Arizona delivery points -- EPNG is the only remaining California alternative and may lack sufficient spare capacity to fully absorb displaced volumes.
Reroute potential
Limited: EPNG is the primary competing pipeline for SoCal border and Arizona deliveries, but a simultaneous EPNG constraint would eliminate all California reroute; even absent a concurrent EPNG event, EPNG spare capacity may be insufficient to absorb full East Mainline volumes on short notice.
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