Mich. Comp. Laws § 123.64

Sec. 4. A county board of commissioners may provide funds for 1 or more of the following purposes by an appropriation from the county general fund and may raise these funds by an ad valorem property tax levy on property within the county subject to taxation for county purposes, but, except upon approval of a majority of the qualified electors of that county voting on a question of whether to increase this limitation, said tax shall never exceed in any 1 year 1/4 of 1 mill on the equalized valuation of the county: (a) Purchasing or acquiring by condemnation property for a public park, zoological garden, airport, or other purpose authorized by this act. (b) Improving or maintaining property purchased or acquired pursuant to subdivision (a). (c) Contributing towards the maintenance of a public park, zoological garden, airport, or other facility authorized by this act which is owned or held in trust by a township, city, or village within the county, or by an adjoining county.