The treasurer of the county in which a port district is located shall be treasurer of the district unless the commission of a port district which has for the last three consecutive years received annual gross operating revenues of one hundred thousand dollars or more, excluding tax revenues and grants for capital purposes, designates by resolution some other person having experience in financial or fiscal matters as treasurer of the port district to act with the same powers and under the same restrictions as provided by law for a county treasurer acting on behalf of a port district: PROVIDED, That any port district which was authorized by the county treasurer to appoint its own treasurer prior to July 24, 1983, may continue to appoint its own treasurer. The commission may, and if the treasurer is not the county treasurer it shall, require a bond, with a surety company authorized to do business in the state of Washington, in an amount and under the terms and conditions which the commission by resolution from time to time finds will protect the district against loss. The premium on such bonds shall be paid by the district. All district funds shall be paid to the treasurer and shall be disbursed by him or her upon warrants signed by a port auditor appointed by the port commission, upon vouchers approved by the commission.