Summary
Transwestern Pipeline declared force majeure on its East Mainline, effective Aug 19 2026 9:00AM through Aug 20 2026 8:59AM -- a roughly 24-hour window. The East Mainline is the outbound corridor carrying Permian and San Juan Basin gas westward toward SoCal/Arizona delivery points. No specific capacity volume is stated in the notice.
Trading note
TW East Mainline force majeure creates a split-direction signal: expect bearish pressure at Transwestern Permian basis (most recently -0.815 vs HH on 2026-08-18, five-day average -0.856) and Waha as basin gas is trapped, with bullish pressure at SoCal Gas border as westbound supply is reduced; EPNG is the only remaining reroute path to California, so SoCal basis spike risk is elevated for the Aug 19 gas day.
Reroute potential
Moderate: EPNG is the primary competing pipeline for SoCal border deliveries and remains the sole alternative while TW East Mainline is under force majeure; however, EPNG alone cannot fully replace TW volumes if it is operating near capacity, and any simultaneous EPNG constraint would leave California with zero reroute.
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View original notice text (as posted by Transwestern Pipeline)
Pipeline: Transwestern Pipeline
Notice ID: 120082
Notice Type: Capacity Constraint
Subject: EAST MAINLINE
Posted: Aug 18 2026 6:36PM
Effective: Aug 19 2026 9:00AM
End Date: Aug 20 2026 8:59AM
Notice Type Description: Capacity Constraint
Notice Identifier: 120082
Critical Notice Description: Critical notice
Posting Date/Time: Aug 18 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 19 2026 9:00AM
Notice End Date/Time: Aug 20 2026 8:59AM
Reason: Force Majeure
Location: EAST MAINLINE
