The Environmental Protection Agency (EPA) is approving a revision to the Washington State Implementation Plan (SIP) that was submitted by the Department of Ecology (Ecology) in coordination with the Spokane Regional Clean Air Agency (SRCAA). This revision updates the SIP with local SRCAA regulations that apply in lieu of, or in supplement to, Ecology's statewide general air quality regulations for SRCAA's jurisdiction. We are also approving SRCAA's adoption by reference of certain Ecology general air quality regulations, which do not have local agency replacement corollaries, to apply in SRCAA's jurisdiction.