Mich. Comp. Laws § 97.4

Sec. 4. The council may provide by ordinance for the preservation of the purity of a body of water within the city, and within 1/2 mile from the corporate boundaries of the city; prohibit and impose sanctions for the depositing of filth, logs, floating matter, or any injurious thing in such a body of water; control and regulate the anchorage, moorage, and management of watercraft and floats within the jurisdiction of the city; prescribe the mode and speed of entering and leaving the harbor, if any, and of coming to and departing from the docks, wharves, and landings, by watercraft and floats; regulate and prescribe, by ordinances or through a harbormaster or other officer, the location for a watercraft or float, and the changes of station in and use of the harbor required to promote order in the harbor and the safety and convenience of watercraft and floats; and enact and enforce ordinances and regulations that in the opinion of the council are most conducive to the orderly, safe, and convenient use and occupancy of the navigable waters, wharves, docks, piers, and landing places within the city.