Wash. Rev. Code § 53.46.090
Upon receipt of the certificate from the principal county auditor as provided in RCW 53.46.080 it shall be the duty of the board of county commissioners of each county to levy on all taxable property of the consolidated port district which lies within the county a tax sufficient to raise the amount necessary to meet the county's proportionate share of the total tax levy. Such taxes shall be levied and collected in the same manner as other taxes are levied and collected. The proceeds shall be forwarded quarterly by the treasurer of each county to the principal county treasurer. The principal county treasurer shall place to the credit of said consolidated port district all funds received from the other county treasurers as well as those amounts he or she shall have collected for the account of the port district. The principal county treasurer shall be the treasurer of the consolidated port district and shall perform all functions required of a treasurer of a port district.
RCW 53.46.090