The county executive, with the advice of the county health officer, is hereby authorized at any time and from time to time to negotiate and contract with any hospital accredited by the American Hospital Association and the American College of Surgeons for the care in such hospitals of indigent and medically indigent residents of the county who are certified by the county welfare board as eligible for payment of cost of care by the county, pursuant to rule 900 of the manual of the state department of public welfare. (Mont. Co. Code 1965, § 89-56; 1970 L.M.C., ch. 25, § 1; 1972 L.M.C., ch. 16, § 13.)