Wash. Rev. Code § 85.05.081
In all proceedings hereafter had to organize diking districts, all notices, petitions or proceedings shall contain and set forth all matters and things required by existing law, and in addition thereto shall contain and set forth, so far as is necessary or applicable, all matters and things required by the provisions of this act, and all diking districts now existing, which may exercise any of the rights, powers or authority conferred by the provisions of this act, the proceedings to obtain the benefits hereof, must contain such allegations, and such steps and proceedings must be taken, as is rendered necessary by the provisions of this act; and the commissioners of existing diking districts are hereby given the right, power and authority to institute all proceedings and to take all necessary steps to secure the benefits of the provisions of this act, and all proceedings to secure the benefits thereof and all judgments to be rendered in such proceedings, including the filing of transcripts and the making of levies, and all other proceedings, shall be in addition to proceedings, assessments or levies, theretofore made in any prior proceedings.
RCW 85.05.081