Wash. Rev. Code § 67.38.150
Unless the cultural arts, stadium and convention district governing body, by resolution, designates some other person having experience in financial or fiscal matters as treasurer of the district, the treasurer of the county in which a cultural arts, stadium and convention district is located shall be ex officio treasurer of the district: PROVIDED, That in the case of a multicounty cultural arts, stadium and convention district, the county treasurer of the county with the greatest amount of area within the district shall be the ex officio treasurer of the district. The district may, and if the treasurer is not a county treasurer shall, require a bond for such treasurer with a surety company authorized to do business in the state of Washington, in an amount and under the terms and conditions as agreed to by the district, by resolution, in such amount from time to time which will protect the authority against loss. The premium on any such bond shall be paid by the authority.
All district funds shall be paid to the treasurer and shall be disbursed by the treasurer only on warrants issued by an auditor appointed by the district, upon orders or vouchers approved by the governing body. The treasurer shall establish a "cultural arts, stadium and convention fund," into which shall be paid district funds as provided in RCW 67.38.140 and the treasurer shall maintain such special funds as may be created by the governing body into which said treasurer shall place all moneys as the governing body may, by resolution, direct.
If the treasurer of the district is a treasurer of the county, all district funds shall be deposited with the county depositary under the same restrictions, contracts, and security as provided for county depositaries; the county auditor of such county shall keep the records of the receipts and disbursements, and shall draw, and such county treasurer shall honor and pay all warrants, which shall be approved before issuance and payment as directed by the district.
RCW 67.38.150