(1) The powers of the port district shall be exercised through a port commission consisting of three or, when permitted by this title, five members. Every port district that is not coextensive with a county having a population of five hundred thousand or more shall be divided into the same number of commissioner districts as there are commissioner positions, each having approximately equal population, unless provided otherwise under subsection (2) of this section. Where a port district with three commissioner positions is coextensive with the boundaries of a county that has a population of less than five hundred thousand and the county has three county legislative authority districts, the port commissioner districts shall be the county legislative authority districts. In other instances where a port district is divided into commissioner districts, the port commission shall divide the port district into commissioner districts unless the commissioner districts have been described pursuant to RCW 53.04.031. The commissioner districts shall be altered as provided in chapter 53.16 RCW.

Commissioner districts shall be used as follows: (a) Only a registered voter who resides in a commissioner district may be a candidate for, or hold office as, a commissioner of the commissioner district; and (b) only the voters of a commissioner district may vote at a primary to nominate candidates for a commissioner of the commissioner district. Voters of the entire port district may vote at a general election to elect a person as a commissioner of the commissioner district.

(2)(a) In port districts with five commissioners, two of the commissioner districts may include the entire port district if approved by the voters of the district either at the time of formation or at a subsequent port district election at which the issue is proposed pursuant to a resolution adopted by the board of commissioners and delivered to the county auditor.

(b) In a port district with five commissioners, where two of the commissioner districts include the entire port district, the port district may be divided into five commissioner districts if proposed pursuant to a resolution adopted by the board of commissioners or pursuant to a petition by the voters and approved by the voters of the district at the next general or special election occurring sixty or more days after the adoption of the resolution. A petition proposing such an increase must be submitted to the county auditor of the county in which the port district is located and signed by voters of the port district at least equal in number to ten percent of the number of voters in the port district who voted at the last general election.

Upon approval by the voters, the commissioner district boundaries shall be redrawn into five districts ((within one hundred twenty days))prior to the first day of January in the year in which the two additional commissioners shall be elected and submitted to the county auditor pursuant to RCW 53.16.015. The new commissioner districts shall be numbered one through five and the three incumbent commissioners representing the three former districts shall represent commissioner districts one through three. The two at large incumbent commissioners shall represent commissioner districts four and five. If, as a result of redrawing the district boundaries more than one of the incumbent commissioners resides in one of the new commissioner districts, the commissioners who reside in the same commissioner district shall determine by lot which of the numbered commissioner districts they shall represent for the remainder of their respective terms.

The port commissioners shall divide the port district into five commissioner districts prior to the first day of ((June))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.