WASHINGTON STATE DEPARTMENT OF ECOLOGY NOTICE OF PUBLIC COMMENT PERIOD SEPA MDNS for the Northwest Williams Pipeline Huntingdon Connector project Comment Period: June 15 (12:00 AM) – June 30, 2026 (11:59 PM) Project locations: • Sumas Compressor Station, 4738 Jones Road, Sumas, WA 98295. • Mt. Vernon Compressor Station,1539 Lange Road, Mount Vernon, WA 98273. • Snohomish Compressor Station, 22902 Echo Lake Road, Snohomish, WA 98296 • Sumner Compressor Station, 3104 166th Ave. East, Lake Tapps, WA 98391 Submit comments online at https://ecology.commentinput.com?id=kbx2Y6KmWJ or mail to Tom Buroker, WA Department of Ecology, Northwest Region Office, PO Box 330316 Shoreline, WA 98133-9716. To review project documents, visit https://apps.ecology.wa.gov/separ/Main/SEPA/Record.aspx?SEPANumber=202602451 Proposed project: Huntingdon Connector Compressor Upgrades Project Williams Northwest Pipeline LLC (Northwest) is proposing a project to increase the efficiency and capacity of Northwest's existing natural gas pipeline system by uprating and modifying equipment at four of Northwest's existing compressor stations: Sumas (Whatcom County), Mt. Vernon (Skagit County), Snohomish (Snohomish County), and Sumner (Pierce County). The Project is designed to deliver up to 77.99 thousand decatherms per day (Mdth/d) of incremental firm transportation capacity in western Washington. The WA Department of Ecology, Northwest Clean Air Agency and Puget Sound Clean Air Agency, acting as co-lead agencies, are issuing a SEPA mitigated determination of nonsignificance and starting a 14-day public comment period for the environmental review of the project. The project optimizes fuel usage by uprating and re-wheeling existing compressor units, installing emissions reducing equipment, and providing incremental firm transportation capacity through efficiency gains at the existing Project compressor stations. All construction activities will occur within previously developed industrial sites, avoiding new land disturbance or impacts to surrounding land uses. Public comment periods are also underway for the air quality permits. For more information, visit https://nwcleanairwa.gov/public-notices/ (for the Sumas compressor) and https://pscleanair.gov/175/Permits-Open-for-Comment (for the Snohomish compressor). Questions? Contact Meg Bommarito at Meg.Bommarito@ecy.wa.gov or 425-681-6236. IPL0348844 Jun 15 2026