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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View original notice text (as posted by Transwestern Pipeline)
Pipeline: Transwestern Pipeline
Notice ID: 120058
Notice Type: Capacity Constraint
Subject: EAST MAINLINE
Posted: Aug 17 2026 6:36PM
Effective: Aug 18 2026 9:00AM
End Date: Aug 19 2026 8:59AM
Notice Type Description: Capacity Constraint
Notice Identifier: 120058
Critical Notice Description: Critical notice
Posting Date/Time: Aug 17 2026 6:36PM
Notice Status Description: Initiate
Required Response Indicator Description: No response required
TSP: 7933047
TSP Name: TRANSWESTERN PIPELINE COMPANY, LLC
Subject: EAST MAINLINE
Notice Effective Date/Time: Aug 18 2026 9:00AM
Notice End Date/Time: Aug 19 2026 8:59AM
Reason: Force Majeure
Location: EAST MAINLINE
