PUBLIC NOTICE PUGET SOUND CLEAN AIR AGENCY Proposed Order of Approval No. 12553 Northwest Pipeline LLC Snohomish 22902 Echo Lake Rd, Snohomish, WA The Puget Sound Clean Air Agency is providing public notice for a proposed permit for Northwest Pipeline LLC Snohomish to overhaul one of the two natural gas-fueled combustion turbines at the Snohomish compressor station. Currently, the two turbines are each rated at approximately 12,639 horsepower; this project would uprate one of the turbines to approximately 17,274 horsepower. This upgrade will lower nitrogen oxide emissions by approximately ten tons per year and increase carbon monoxide emissions by approximately sixteen tons per year. All other pollutants are expected to have nominal changes that are less than one ton per year. After this project, the facility’s total potential to emit all pollutants will be below the major source operating permit thresholds. Therefore, this facility will no longer be classified as a “synthetic minor” facility and will instead be considered a “natural minor” facility. PRELIMINARY DETERMINATION The Agency has completed a review of application No. 12553. Based on this review, the Agency has made a preliminary determination that the proposal meets all the requirements of Regulations I, II, and III, and draft Order No. 12553 should be approved, subject to the conditions in the draft Order of Approval. The draft Order of Approval will be open for public comment through 4:30 PM PDT on July 16, 2026. This turbine upgrade project is a component of the larger Northwest Pipeline Huntingdon Connector Project. The Department of Ecology, with the Puget Sound Clean Air Agency and the Northwest Clean Air Agency as co-lead agencies, has issued a Mitigated Determination of Nonsignificance (MDNS) for the Huntingdon Connector Project. The Environmental Checklist and MDNS for the Huntingdon Connector Project are available on the Department of Ecology’s SEPA Register website at https://apps.ecology.wa.gov/separ/Main/SEPA/Search.aspx. The comment period for the MDNS closes at 11:59 PM PT on June 30, 2026. PUBLIC COMMENT The proposed Order of Approval (along with the information considered in making this preliminary determination) is available from the Agency’s website at www.pscleanair.gov. These documents are also on file and available for inspection at the Agency’s office located at 1904 Third Avenue, Suite 105, Seattle, Washington, telephone (206) 343-8800. Written comments with respect to the proposed Order must be mailed to Carl Slimp, Engineer, at Puget Sound Clean Air Agency, 1904 Third Avenue, Suite 105, Seattle, Washington 98101, faxed to the Engineering Manager at (206) 343-7522, or e-mailed to PublicComment@pscleanair.gov by 4:30 pm PDT on July 16, 2026. Comments may also be submitted orally at a public hearing. The public hearing on the proposed Order of Approval will be held on Zoom on July 16, 2026. The hearing will begin at 10 AM PDT and will end when all who wish to comment have spoken, but no earlier than 10:15 AM. The hearing may be accessed at the following web address: https://us02web.zoom.us/j/81537862597 Meeting ID: 815 3786 2597 Passcode: 336845 The hearing may also be accessed by phone by dialing (253) 215-8782 and entering the Meeting ID and Passcode listed above. All comments received during the comment period will become part of the public record. Once the Agency has reviewed and responded to comments from the public, the proposed Order of Approval will, if necessary, be revised and either denied or issued in final form. Published: June 16, 2026. EDH1032338

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