Wash. Rev. Code § 85.05.230
Where any diking system is sought to be constructed by any district organized under the provisions of this act along any river or watercourse to prevent overflow therefrom, and it shall become necessary to provide against the washing away of the banks of said river or watercourse so as to prevent injury to such proposed diking system, or any system which may have already been completed, such district, by and through its board of commissioners, may make such portions of lands lying along said dikes which are threatened to be washed away by said river or watercourse part of the right-of-way of said dike system, and may construct along the banks of said river or watercourse, as a part of said diking system, such protection as may be necessary to protect said dike, and in such cases such tract or parcel of land may be condemned and appropriated under the law of eminent domain as provided herein as a part of the right-of-way of such dike system; and when not condemned or appropriated at the time said system is established and constructed, said diking district, by and through its board of commissioners, may, at any time thereafter, when any portion of said system is threatened to be washed away by such river or watercourse, file their petition with the court condemning and appropriating for the use of said district so much of the land lying along said river or watercourse as may be necessary to be used for the protection of said diking system, and the proceedings therein for the making of compensation therefor and the payment of damages by reason of such appropriation shall be the same, or as near as may be applicable, as other proceedings for the condemnation of right-of-way provided for in this act.
RCW 85.05.230