Each county which designates the Washington state association of county officials as the agency through which the duties imposed by RCW
36.47.020 may be executed is authorized to reimburse the association from the county current expense fund for the cost of any such services rendered: PROVIDED, That no reimbursement shall be made to the association for any expenses incurred under RCW
36.47.050 for travel, meals, or lodging of such county officials, or their representatives at such meetings, but such expenses may be paid by such official's respective county as other expenses are paid for county business. Such reimbursement shall be paid only on vouchers submitted to the county auditor and approved by the legislative authority of each county in the manner provided for the disbursement of other current expense funds. Each such voucher shall set forth the nature of the services rendered by the association, supported by affidavit that the services were actually performed.