Wash. Rev. Code § 91.08.130
The board shall file a petition, verified by its chair and signed by the prosecuting attorney, in the superior court of the county, praying that the property described may be taken or damaged for the purpose specified and that compensation therefor be ascertained by a jury or by the court in case a jury be waived. Such petition shall allege the creation of the waterway district and contain a copy of the order directing the proceeding, a reasonably accurate description of the lots or parcels of land or other property which will be taken or damaged, and the names of the owners and occupants of said lands and of said persons having any interest therein so far as known to the said board, or as appears from the records in the office of the county auditor.
RCW 91.08.130