Idaho Code § 31-3504
Recognizing the need of hospitals for the public welfare and the burden for one (1) county to finance the cost of such construction, operation and maintenance thereof within its own boundaries under certain circumstances, the county commissioners in their respective counties shall have the power to jointly and severally enter into contracts or agreements with one (1) or more adjoining counties to construct, operate and maintain joint county hospitals, either within or without the boundaries of such counties, upon a finding of each such county commissioners that there is a public necessity requiring the financing of such hospital facilities jointly with one (1) or more adjoining counties. The county commissioners shall have the same powers to operate, finance and bond for such joint county hospitals as they would have for a county hospital.
Idaho Code § 31-3504