Designation of Areas for Air Quality Planning Purposes; Redesignation Request and Associated Maintenance Plan for Whatcom County, WA 2010 SO2 Nonattainment Area

On July 25, 2024, the State of Washington (WA) submitted a request for the Environmental Protection Agency (EPA) to redesignate to attainment a portion of Whatcom County immediately surrounding the now permanently closed aluminum smelter, Intalco Aluminum LLC, which the EPA designated nonattainment for the 2010 1-hour primary sulfur dioxide (SO<INF>2</INF>) National Ambient Air Quality Standard (NAAQS). Washington also submitted a request for the EPA to approve a State Implementation Plan (SIP) revision containing a maintenance plan for the area. The EPA is taking the following final actions: we have determined that the Whatcom County (partial) SO<INF>2</INF> nonattainment area (Whatcom County area or area) is attaining the 2010 1-hour primary SO<INF>2</INF> NAAQS; we are approving Washington's plan for maintaining attainment of the 2010 1- hour primary SO<INF>2</INF> NAAQS in the area; and we are redesignating the Whatcom County area to attainment for the 2010 1-hour primary SO<INF>2</INF> NAAQS.