Mich. Comp. Laws § 331.203
The board of supervisors of any county coming within the provisions of section 2 of this act, is hereby authorized and empowered to raise by taxation necessary funds for the purpose of acquiring, owning, constructing, equipping, maintaining and operating a hospital for the treatment of contagious or infectious diseases and for the treatment of indigent persons suffering from any physical ailment or impairment, and for temporary detention of mentally ill patients, both non-indigent and indigent. In no case shall a tax for the original acquisition and construction exceed in any 1 year 1 mill on each dollar of the assessed valuation of said county. If deemed expedient by said board, moneys for acquisition or construction purposes hereunder may be raised by taxation during successive years, and said board of supervisors may also appropriate from any unexpended moneys in the general fund of the county for such purposes. All money raised by taxation within the county, and all moneys appropriated by said board of supervisors for such purposes, shall constitute a special fund for acquisition or construction and equipment of the hospital. Moneys raised by taxation or appropriated by the board of supervisors for acquisition or construction purposes, and subsequently found not to be needed therefor, may be used to defray the expenses of operation and maintenance.
MCL 331.203