Wash. Rev. Code § 35.59.020
The legislature finds that in many areas of the state local services and facilities can be more effectively and economically provided by combining two or more services and/or facilities in a single multi-purpose community center or a system of such centers. Any municipality shall have and exercise the authority and powers granted by this chapter whenever it appears to the legislative body of such municipality that the acquisition, construction, development and operation of a multi-purpose community center or a system of such centers will accomplish one or more of the following: Reduce costs of land acquisition, construction, maintenance or operation for affected public services or facilities; avoid duplication of structures, facilities or personnel; improve communication and coordination between departments of a municipality or governmental agency or between municipalities and governmental agencies; make local public services or facilities more convenient or useful to the residents and citizens of such municipality.
RCW 35.59.020