Wash. Rev. Code § 53.46.010
Two or more port districts may be joined into one consolidated port district in the following manner: The port commissioners of each of the port districts proposed to be consolidated may, or on petition of ten percent of the qualified electors residing within each of the districts proposed to be consolidated based on the total vote cast in the last general election, shall, by joint resolution submit to the qualified electors of the port districts to be consolidated the proposition of consolidating such districts into one port district. Such resolution or petition in request thereof shall identify each port district to be consolidated, listing its assets and liabilities; state the name by which the port district resulting from the consolidation shall be known; legally describe each port commissioner district to be created within the port district resulting from the consolidation; state the terms and conditions, if any, under which the consolidation is proposed; and call a special election in the territory of the port districts to be consolidated, to determine whether such consolidation shall take place, and to fill the offices of the port commission of the port district resulting from the consolidation. The resolution or petition shall provide that the commission in the proposed district shall consist of three, five, or seven commissioners and that the number shall be approved by the voters at the time the proposition for consolidation is voted upon. The proposition in this respect shall provide that the commissioners shall be elected one each from commissioner districts which shall be described as set forth in this section, or if such districts are not so described then the commissioners shall be elected at large.
RCW 53.46.010