Idaho Code § 31-2705
Whenever it shall be ordered by an act of the legislature to establish the boundary line between two (2) counties, the board of county commissioners of each county interested in the boundary shall jointly select and retain the services of a professional land surveyor to establish said boundary line, or each county shall select and retain the services of a professional land surveyor who shall jointly establish said boundary, and firmly plant and mark corners and monuments of imperishable material, also to prepare plats and field notes jointly, one (1) copy of which shall be filed with the auditor and recorder of each of the counties so interested. The fees and compensations for such surveys, plats and field notes, shall be paid out of the county treasury upon the order of the county commissioners of each county to the respective surveyors so employed.
Idaho Code § 31-2705