Wash. Rev. Code § 35.59.040
Any municipality, and any agency, subdivision, taxing district or municipal corporation of the state is authorized to convey or lease any lands, properties or facilities to any other municipality for the development by such other municipality of a multi-purpose community center or a system of such centers or to provide for the joint use of such lands, properties or facilities or any other facilities of a multi-purpose community center, and is authorized to participate in the financing of all or any part of such multi-purpose community center or system of such centers on such terms as may be fixed by agreement between the respective legislative bodies without submitting the matter to a vote of the electors thereof, unless the provisions of the Constitution or laws of this state applicable to the incurring of indebtedness shall require such submission.
RCW 35.59.040
Joint operations by municipal corporations, deposit and control of funds: RCW 43.09.285.