Michigan Compiled Laws, Chapter 333. Health § 333.2415

Sec. 2415. Two or more counties or a city having a population of 750,000 or more and 1 or more counties, by a majority vote of each local governing entity and with approval of the department, may unite to create a district health department. The district board of health shall be composed of 2 members from each county board of commissioners or in case of a city-county district 2 members from each county board of commissioners and 2 representatives appointed by the mayor of the city. With the consent of the local governing entities affected, a county or city may have a greater number of representatives.