Mich. Comp. Laws § 141.65

Sec. 5. This act and the powers and authority hereby granted shall be deemed cumulative and confirmatory of powers heretofore or hereafter granted to counties to borrow money or incur obligations for county purposes or issue bonds of the county or contract to secure repayment of moneys borrowed. If provision was heretofore or hereafter made for borrowing money, incurring obligations, or issuing bonds by counties, those provisions or the provisions of this act may be followed at the election of county authorities.