Wash. Rev. Code § 68.54.040
The board of the merger district may, by resolution, reject the petition, or it may concur therein as presented, or it may modify the terms and conditions of the proposed merger, and shall transmit the petition, together with a copy of its resolution thereon to the merging district. If the petition is concurred in as presented or as modified, the board of the merging district shall forthwith present the petition to the auditor of the county in which the merging district is situated, who shall within thirty days examine the signatures thereon and certify to the sufficiency or insufficiency thereof, and for that purpose he or she shall have access to all registration books and records in the possession of the registration officers of the election precincts included, in whole or in part, within the merging district. Such books and records shall be prima facie evidence of truth of the certificate. No signatures may be withdrawn from the petition after the filing.
RCW 68.54.040