Idaho Code § 42-2801
The boards of county commissioners of the several counties of the state of Idaho are hereby authorized and empowered to make all necessary orders for and cause to be constructed and maintained public drainage or irrigation systems, reservoirs, drains and ditches and other irrigation or drainage works for the irrigation or drainage of lands lying in said counties, and for such purposes, to enter into contracts for the construction or use of reservoirs and other irrigation or drainage works, constructed or to be constructed by the United States under the provisions of the federal reclamation laws, or for such works built or to be built by other parties or agencies and to take all steps and do all acts necessary or proper to secure an ample water supply for the lands in the county requiring irrigation and adequate drainage works for the lands requiring drainage, and to promote the beneficial use of the public waters of the state and the health and general welfare of the county by means of such works: provided, that nothing herein contained shall be construed to give such board of county commissioners authority over irrigation works except those acquired or constructed by the several counties under the provisions of this chapter: provided, also, that no county bonds shall be issued or sold for such purposes until such indebtedness has been authorized by two-thirds (2/3) of the electors of the county (having the qualifications provided in section 42-2803, Idaho Code,) voting at an election to be held, subject to the provisions of section 34-106, Idaho Code, for such purpose.
Idaho Code § 42-2801