Wash. Rev. Code § 89.30.013
Said petition shall describe the lands proposed to be irrigated in township and ranges and in case of smaller bodies of land, in legal subdivisions or fractions thereof, shall give the name of the county in which said respective irrigable lands are situated, and shall state all the possible sources of water supply from which said lands can be irrigated: PROVIDED, That nothing herein contained shall be construed to limit the power of any district organized under the provisions of this chapter to utilize any other source of water supply not mentioned in the petition. Said petition shall also define the boundaries of the proposed district, which said boundaries shall include all of the lands, a major portion of which can be irrigated from the proposed sources of water supply, shall give the name by which the petitioners desire the district to be designated and shall state that the petitioners desire to have the territory included within the boundaries defined, organized into a reclamation district under the provisions of this chapter.
RCW 89.30.013