Idaho Code § 42-2809
For the purpose of performing the acts and exercising the powers granted by section 43-1801 of the Idaho Code and the act of Congress of August 11, 1916, entitled "An Act to Promote Reclamation of Arid Lands," (39 Stat. 506), counties in which irrigation projects have been duly established by order of the board of county commissioners under the provisions of this chapter, shall be considered to be irrigation districts of the state of Idaho and vested with all the powers and authority granted to irrigation districts by said section 43-1801 of the Idaho Code, and by the said act of Congress of August 11, 1916, entitled "An Act to Promote the Reclamation of Arid Lands," and the board of county commissioners of such counties are authorized to act as the directors of such district for such purpose and to exercise all the powers granted to the directors of irrigation districts.
Idaho Code § 42-2809