Wash. Rev. Code § 70A.15.1610
The treasurer of each component city, town, or county shall create a separate fund into which shall be paid all money collected from taxes or from any other available sources, levied by or obtained for the activated authority on property or on any other available sources in such city, town, or county . The collected money shall be forwarded quarterly by the treasurer of each such city, town, or county to the treasurer of the county designated by the board as the treasurer for the authority. The treasurer of the county designated to serve as treasurer of the authority shall establish and maintain funds as authorized by the board.
Money shall be disbursed from funds collected under this section upon warrants drawn by either the authority or the auditor of the county designated by the board as the auditor for the authority, as authorized by the board.
If an authority chooses to use a county auditor for the disbursement of funds, the respective county shall be reimbursed by the board for services rendered by the auditor of the respective county in connection with the disbursement of funds under this section.
RCW 70A.15.1610