Idaho Code § 42-2707
Whenever the board of county commissioners of any county shall adjudge that it is desirable and for the general welfare and benefit of the people of the county and for the interest of the county to convey real property belonging to the county, however acquired, whether by tax foreclosure or in any other manner, not necessary for the use of the county, to the United States of America for use in connection with federal projects within the scope of the federal Reclamation Act of June 17, 1902, and federal acts amendatory thereof and supplemental thereto, for the reclamation and irrigation of arid lands, such board of county commissioners, by majority vote, are hereby authorized to convey such property to the United States of America for use in connection with such federal projects as aforesaid for the reclamation and irrigation of arid lands.
Idaho Code § 42-2707