Wash. Rev. Code § 36.32.054
(2) Within sixty days of publishing the draft districting plan, the committee must:
(d) Either:
(6) Each commissioner district established by a redistricting committee under this section must comprise as nearly as possible one-fifth of the population of the county. The boundaries of commissioner districts must:
[ 2018 c 301 s 5.]
Findings—Short title—2018 c 301: See notes following RCW 36.32.051.