Mich. Comp. Laws § 124.281

Sec. 1. As used in this act: (a) "Authority", unless the context clearly implies a different meaning, means an authority incorporated under section 2. (b) "Constituent municipality" or "constituent municipalities" includes all of the municipalities that signed or became signatories of articles of incorporation of any authority incorporated under this act. However, if an authority is incorporated by 2 or more counties, each municipality within the respective territorial limits of the counties, whether the counties are original incorporators or subsequently became a constituent part of the authority under section 6, is a constituent municipality. (c) "Indian tribe" means an Indian tribe, band, nation, or other organized group or community of Indians that is recognized as eligible for services by the United States secretary of the interior because of their status as Indians. (d) "Municipality" means a county, township, city, or village. (e) "Sewage disposal system" includes all interceptor sewers, storm sewers, sanitary sewers, combined sanitary and storm sewers, sewage treatment plants, and all other plants, works, instrumentalities, and properties used or useful in connection with the collection, treatment, or disposal of sewage or industrial wastes. (f) "Solid waste management system" includes all plants, works, instrumentalities, and properties used or useful in connection with the collection, transportation, processing, or disposal of discarded or waste materials of any sort, including access roads and facilities for resource recovery. Solid waste management system does not include the storage or disposal of toxic materials. (g) "Water supply system" includes all plants, works, instrumentalities, and properties used or useful in connection with obtaining a water supply, the treatment of water, or the distribution of water.