Wash. Rev. Code § 66.40.100
Upon the filing of a petition as hereinbefore provided, the county auditor with whom it is filed shall cause the names on said petition to be compared with the names on the voters' official registration records provided for by law with respect to such unit. The officer or deputy making the comparison shall place his or her initials in ink opposite the signatures of those persons who are shown by such registration records to be legal voters and shall certify that the signatures so initialed are the signatures of legal voters of the state of Washington and of said unit, and shall sign such certificate. In the event that said petition, after such comparison, shall be found to have been signed by the percentage of legal voters of said unit referred to in RCW 66.40.040, the question shall be placed upon the ballot at the next general election.
RCW 66.40.100