Summary
Great Lakes Gas Transmission declared unplanned maintenance at Shelvin Compressor Station 3, reducing Emerson Eastbound (LOC #3833975) available capacity to 1.276 Bcf/d effective 08/21/2026 09:00 through 09/25/2026 09:00 -- a 36-day outage. GLGT explicitly warns this may result in Firm Primary (estimated 23% impact), Firm Secondary, and Interruptible curtailments, triggering the Reservation Charge Crediting Mechanism under Section 6.10.3(d). The live EMERSON RECEIPT meter (loc 33975) posted operating capacity of 2.34 Bcf/d on the evening cycle of 2026-08-20 with 1.35 Bcf/d scheduled, indicating the restriction will materially cut into currently flowing volumes.
Trading note
Unplanned GLGT constraint reduces Emerson Eastbound to 1.276 Bcf/d with 23% firm primary curtailment risk, tightening Western Canadian supply into the Upper Midwest; Emerson/Viking GL basis was already deeply negative at -1.655 vs HH on 2026-08-19 (5-day average -1.562), and this outage is bullish for Chicago citygate and Dawn Ontario as Canadian throughput to those markets is squeezed for 36 days starting 08/21.
Reroute potential
Limited: GLGT is the primary Western Canadian import path into Minnesota, Wisconsin, and Michigan; ANR and other Gulf/Midcontinent-sourced pipes serve overlapping Midwest markets but cannot directly replace WCSB volumes entering at Emerson, and the scale of firm curtailments (23% of primary firm) limits full offset.
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View original notice text (as posted by Great Lakes Gas Transmission)
TSP Name: Great Lakes Gas Transmission Limited Partnership
Notice ID: 1223
TSP: 046077343
Notice Type: Maint
Notice Status: Initiate
Posting Date/Time: 08/20/2026 11:05
Notice Eff Date: 08/21/2026
Notice Eff Time: 09:00
Notice End Date: 09/26/2026
Notice End Time: 09:00
Critical: Yes
Required Response: No response required
Subject: CAPACITY REDUCTION GLGT – Emerson Eastbound (Posted: 8/20/26)
Message Text:
Great Lakes Gas Transmission has unplanned maintenance at Shelvin compressor station 3. As a result, capacity will be reduced as follows: Emerson Eastbound (LOC #3833975): 8/21 – 9/25 Available capacity is 1,276 MMcf/d Great Lakes Gas Transmission anticipates that this may result in Firm Primary, Firm Secondary and Interruptible curtailments. The estimated impact to Firm Primary is 23%. The Reservation Charge Crediting Mechanism of Section 6.10.3(d) shall apply to this outage. Please refer to the maintenance schedule for any additional capacity impacts. Please direct any questions to your Account Coordinator, Customer Service Representative, or the Nominations and Scheduling hotline @ 866-454-7572.
