Wash. Rev. Code § 87.03.560
The holder or holders of title, or evidence of title, representing one-half or more of any body of lands may file with the board of directors of an irrigation district a petition in writing, praying that the boundaries of the district may be so changed as to include such lands. The petition shall describe the boundaries of the parcel or tract of land, and shall also describe the boundaries of the several parcels owned by the petitioners, if the petitioners be the owners respectively of distinct parcels, but such descriptions need not be more particular than they are required to be when such lands are entered by the county assessor in the assessment book. Such petition must contain the assent of the petitioners to the inclusion within the district of the parcels or tracts of land described in the petition, and of which the petition alleges they are respectively the owners; and it must be acknowledged in the same manner that conveyances of land are required to be acknowledged.
RCW 87.03.560
Acknowledgments: Chapter 64.08 RCW.