RCW 52.06.060: Merger by petition.

If three-fifths of all the qualified electors in the merging district sign the petition to merge, no election on the question of the merger is necessary and the auditor, or lead auditor if the merging district is located in more than a single county, shall return the petition, together with a certificate of sufficiency to the board of the merging district. The boards of the respective districts shall then adopt resolutions declaring the districts merged in the same manner and to the same effect as if the merger had been authorized by an election.