Mich. Comp. Laws § 123.381

Sec. 1. As used in this act: (a) "Local unit of government" means any county, city, village, township, school district, port district, metropolitan district or other governmental unit or entity in or of this state; and in or of another state. (b) "Waste disposal system" means sewers, intercepters or waste treatment facilities, and facilities for the collection and disposal of refuse, garbage, liquid and solid waste materials. (c) "Water supply system" means installations including pipe lines and other facilities needed for the pumping, treatment and distribution of water supplies.