Wash. Rev. Code § 87.03.535
For the purpose of organizing a consolidated irrigation district a petition signed by fifty or a majority of the holders of title to, or evidence of title to land susceptible of irrigation within the proposed district shall be presented to the board of county commissioners of the county in which the lands or the greater portion thereof are situated, which petition shall set forth and particularly describe the proposed boundaries of such district, and the name of each existing irrigation district proposed to be included therein, and shall pray that the territory embraced within the boundaries of such proposed district may be organized as a consolidated irrigation district. Such petition shall be accompanied by bond as provided in RCW 87.03.020 and thereupon the same proceedings shall be had for the organization of such consolidated district as is provided in RCW 87.03.020 and 87.03.035 through 87.03.045, and the organization of such consolidated district shall be perfected in the same manner as provided in this chapter for the organization of new districts, except as otherwise provided in this section. The board of directors of each irrigation district proposed to be included in such consolidated district shall be served with a copy of the petition for the organization of such consolidated district together with notice at the time and place of hearing of such petition, at least twenty days prior to such hearing, and the board of county commissioners upon the hearing of such petition shall not grant the same or call an election if it shall appear that the board of directors of any existing irrigation district proposed to be included in such consolidated district have by resolution, regularly passed and entered upon the minutes of the directors meetings of such district, voted against the inclusion of such district into such proposed consolidated district. The board of county commissioners upon the hearing of such petition, shall not modify the boundaries of the proposed district to exclude any of the lands which are contained in any of the existing districts proposed to be included in such consolidated districts, and the order calling an election shall provide an election by the electors of each existing district proposed to be included in such consolidated district, and for an election by the electors of that part of the proposed district not included in any existing district, but no elector may cast more than one vote at such election. Such proposed district shall not be declared organized unless two-thirds of all votes cast in each existing district shall be Irrigation District-Yes, and unless two-thirds of all the votes cast in that part of the proposed district not included in any existing district shall be Irrigation District-Yes. If the organization of such consolidated district is not effected the organization of the district proposed to be included in such consolidated district shall not be affected.
RCW 87.03.535