Wash. Rev. Code § 53.12.130
Two additional port commissioners shall be elected at the next district general election following the election at which voters authorized the increase in port commissioners to five members.
The port commissioners shall divide the port district into five commissioner districts prior to the first day of January in the year in which the two additional commissioners shall be elected, unless the voters approved the nomination of the two additional commissioners from district-wide commissioner districts as permitted in RCW 53.12.010(2). The new commissioner districts shall be numbered one through five and the three incumbent commissioners shall represent commissioner districts one through three. If, as a result of redrawing the district boundaries two or three of the incumbent commissioners reside in one of the new commissioner districts, the commissioners who reside in the same commissioner district shall determine by lot which of the first three numbered commissioner districts they shall represent for the remainder of their respective terms. A primary shall be held to nominate candidates from districts four and five where necessary and commissioners shall be elected from commissioner districts four and five at the general election. The persons elected as commissioners from commissioner districts four and five shall take office immediately after qualification as defined under RCW 29A.04.133.
In a port district where commissioners are elected to four-year terms of office, the additional commissioner thus elected receiving the highest number of votes shall be elected to a four-year term of office and the other additional commissioner thus elected shall be elected to a term of office of two years, if the election is held in an odd-numbered year, or the additional commissioner thus elected receiving the highest number of votes shall be elected to a term of office of three years and the other shall be elected to a term of office of one year, if the election is held in an even-numbered year. In a port district where the commissioners are elected to six-year terms of office, the additional commissioner thus elected receiving the highest number of votes shall be elected to a six-year term of office and the other additional commissioner shall be elected to a four-year term of office, if the election is held in an odd-numbered year, or the additional commissioner receiving the highest number of votes shall be elected to a term of office of five-years and the other shall be elected to a three-year term of office, if the election is held in an even-numbered year. The length of terms of office shall be computed from the first day of January in the year following this election.
Successor commissioners from districts four and five shall be elected to terms of either six or four years, depending on the length of terms of office to which commissioners of that port district are elected.
RCW 53.12.130