RCW 52.02.150: Organization conclusive.

After the expiration of five days from the approval of the resolution of the county legislative authority declaring the district to be organized, and the filing of the certified copies of the resolution of the county legislative authority with the county auditor and the county assessor, the creation of the district is complete and its legal existence cannot thereafter be questioned by any person by reason of a defect in the proceedings for the organization of the district.