RCW 35.22.415
RCW 35.22.415: Municipal airport located in unincorporated area—Subject to county comprehensive plan and zoning ordinances.
Whenever a first-class city owns and operates a municipal airport which is located in an unincorporated area of a county, the airport shall be subject to the county's comprehensive plan and zoning ordinances in the same manner as if the airport were privately owned and operated.