Wash. Rev. Code § 36.56.100
When the rights, powers, functions, and obligations of a metropolitan municipal corporation are transferred pursuant to this chapter, all real and personal property owned by the metropolitan municipal corporation shall become that of the county.
All reports, documents, surveys, books, records, files, papers, or other writings relating to the administration of the powers, duties, and functions transferred pursuant to this chapter and available to the metropolitan municipal corporation shall be made available to the county.
All cabinets, furniture, office equipment, motor vehicles, and other tangible property employed in carrying out the rights, powers, functions, and obligations transferred by this chapter and available to the metropolitan municipal corporation shall be made available to the county.
All funds, credits, or other assets held in connection with powers, duties, and functions herein transferred shall be assigned to the county.
Any appropriations or federal grant made to any committee, division, board, or other department of a metropolitan municipal corporation for the purpose of carrying out the rights, powers, functions, and obligations authorized to be assumed by a county pursuant to this chapter shall on the effective date of such transfer be credited to the county for the purpose of carrying out such transferred rights, powers, functions, and obligations.
RCW 36.56.100