Mich. Comp. Laws § 280.281

Sec. 281. Any municipal corporation may contract to pay all or any part of a special drain assessment for drain improvements made by any county agency or drainage district benefiting property of the municipal corporation, but in no event shall such payment exceed its proportionate share of the expenses of the improvements. For the purposes of this section, "municipal corporation" means any county, township, charter township, city, village, metropolitan district, public authority or a drainage district.