County legislative authorities may designate the Washington state association of counties as a coordinating agency in the execution of duties imposed by RCW
36.32.335 through
36.32.360 and reimburse the association from county current expense funds in the county legislative authority's budget for the costs of any such services rendered. Such reimbursement shall be paid on vouchers submitted to the county auditor and approved by the county legislative authority in the manner provided for the disbursement of other current expense funds and the vouchers shall set forth the nature of the service rendered, supported by affidavit that the service has actually been performed.