Wash. Rev. Code § 36.94.330
The governing body of a municipal corporation proposing to transfer all or part of its property to a county in the manner provided by RCW 36.94.310 through 36.94.350 and the legislative authority of a county proposing to accept such property, and to assume if it so agrees any indebtedness of the municipal corporation in consideration of such transfer, shall adopt resolutions or ordinances authorizing respectively the execution of a written agreement setting forth the terms and conditions upon which they have agreed and finding the transfer and acquisition of property pursuant to such agreement to be in the public interest and conducive to the public health, safety, welfare, or convenience. Such written agreement may include provisions, by way of description and not by way of limitation, for the rights, powers, duties, and obligations of such municipal corporation and county with regard to the use and ownership of property, the providing of services, the maintenance and operation of facilities, the allocation of costs, the financing and construction of new facilities, the application and use of assets, the disposition of liabilities and indebtedness, the performance of contractual obligations, and any other matters relating to the proposed transfer of property, which may be preceded by an interim period of operation by the county of the property and facilities subsequently to be transferred to that county. The agreement may provide for a period of time during which the municipal corporation may continue to exercise certain rights, privileges, powers, and functions authorized to it by law including the ability to promulgate rules and regulations, to levy and collect special assessments, rates, charges, service charges and connection fees, and to adopt and carry out the provisions of a comprehensive plan, and amendments thereto, for a system of improvements and to issue general obligation bonds or revenue bonds in the manner provided by law, or the agreement may provide for the exercise for a period of time of all or some of such rights, privileges, powers, and functions by the county. The agreement may provide that either party thereto may authorize, issue and sell, in the manner provided by law, revenue bonds to provide funds for new water or sewer improvements or to refund or advance refund any water revenue, sewer revenue or combined water and sewer revenue bonds outstanding of either or both such parties. The agreement may provide that either party thereto may authorize and issue, in the manner provided by law, general obligation or revenue bonds of like amounts, terms, conditions and covenants as the outstanding bonds of either or both such parties and such new bonds may be substituted or exchanged for such outstanding bonds to the extent permitted by law.
RCW 36.94.330