Wash. Rev. Code § 89.12.030
The provisions of this chapter shall be applicable to any irrigation or reclamation district organized under the laws of this state contracting or intending to contract with the United States under the federal reclamation laws with respect to a water supply for irrigation from the Columbia Basin project or from any project or division of a project hereafter undertaken in this state by the United States under those laws, and shall govern as to any lands which are now or may hereafter be included in any such district and as to the relationship between any such district and any such lands. The prospect of the construction of the irrigation features of the Columbia Basin project and of other works under the federal reclamation laws for the irrigation of lands in this state requires the granting of authority to irrigation and reclamation districts and to state and county officers to assist the United States, in accordance with the policy of this enactment, in meeting the problems of land speculation and in limiting the size of holdings of lands that may be benefited by such works, and otherwise to cooperate with the United States in connection with the irrigation of lands in this state. The provisions of this chapter, however, are supplemental to other provisions of the law of the state, not inconsistent herewith, which pertain to such districts.
RCW 89.12.030