Wash. Rev. Code § 85.28.020
The person or persons desiring the location and establishment of such ditch or drain may file in the superior court of the county in which the lands sought to be appropriated are situated, a petition showing the name of the petitioner or petitioners; a description of the lands to be benefited, and of those over which the ditch would pass, and setting forth the name of every owner, incumbrancer, or other person or party interested in the lands over which said ditch would pass, or any part thereof, so far as the same can be ascertained from the public records of the county. Such petition shall also show the object for which the lands are sought to be appropriated, the necessity for the appropriation, and the length, width and depth of the ditch on the lands of each separate owner, with a description of said ditch, as nearly as practicable; and shall also set out the estimated damage to the lands of each owner to be crossed by such ditch.
RCW 85.28.020