Wash. Rev. Code § 14.07.030
Any city, town, port district or county is authorized and empowered by and through their corporate authorities to appropriate sums of money and pay the same to any other city, town, port district or county, or deed and convey property already owned to such city, town, port district or county, for use in acquiring and maintaining sites and other facilities for landings, terminals, housing, repair and care of dirigibles, airplanes and seaplanes for the aerial transportation of persons, property, mail or military and naval aircraft and need not require consideration other than the benefit which may be derived by the city, town, port district or county on account of the use therefor and development of such property for said purposes.
RCW 14.07.030