Washington Revised Code Title 29A. Elections § 29A.16.040. Precincts--Boundaries may be altered

(1) Precinct boundaries may be altered at any time as long as sufficient time exists prior to a given election for the necessary procedural steps to be honored. Except as permitted under subsection (3) of this section, no precinct changes may be made during the period starting seven days prior to the first day for candidates to file for the primary election and ending with the day of the general election.

(2) The county legislative authority may establish by ordinance a limitation on the maximum number of active registered voters in each precinct within its jurisdiction. The number may be less than the number established by law, but in no case may the number exceed one thousand five hundred active registered voters.

(3) The county auditor shall temporarily adjust precinct boundaries when a city or town annexes unincorporated territory to the city or town, or whenever unincorporated territory is incorporated as a city or town. The adjustment must be made as soon as possible after the approval of the annexation or incorporation. The temporary adjustment must be limited to the minimum changes necessary to accommodate the addition of the territory to the city or town, or to establish the eligible voters within the boundaries of the new city or town, and remains in effect only until precinct boundary modifications reflecting the annexation or incorporation are adopted by the county legislative authority.