Wash. Rev. Code § 54.40.070
Within thirty days after the public utility district commission divides the district into District A and District B, the county legislative authority shall call a special election, to be held at the next special election date provided for under RCW 29A.04.321 that occurs sixty or more days after the call, at which time the initial commissioners for District A and District B shall be elected. No primary shall be held and a special filing period shall be opened as provided in RCW 29A.24.171 and 29A.24.181. The person receiving the greatest number of votes for each position shall be elected.
The person who is elected receiving the greatest number of votes shall be elected to a four-year term of office, and the other person who is elected shall be elected to a two-year term of office, if the election is held in an even-numbered year, or the person who is elected receiving the greatest number of votes shall be elected to a three-year term of office, and the other person who is elected shall be elected to a one-year term of office, if the election is held in an odd-numbered year. The length of these terms of office shall be calculated from the first day in January in the year following their elections.
The newly elected commissioners shall assume office immediately after being elected and qualified and shall serve until their successors are elected and qualified and assume office in accordance with RCW 29A.60.280. Each successor shall be elected to a four-year term of office.
RCW 54.40.070