Mich. Comp. Laws § 46.173
Whenever the county board of commissioners of a county determines to establish and provide any of the improvements, facilities, or services hereinbefore authorized, it shall designate the "county agency" therefor which shall be the board of county road commissioners, the drain commissioner, or the board of public works of the county as may be determined by resolution of the county board of commissioners. Before commencing the improvements, facilities, or services, or entering into a contract with any other unit of government for supply or use of the improvements, facilities, and services, the county agency shall prepare or obtain from competent sources and file with the county board of commissioners, maps, plans, designs, specifications, and estimates of the proposed improvements or facilities. The county agency shall have supervision and control of the management and operation of all improvements, facilities, and services established pursuant to this act and further shall have the following duties and powers: To make and execute proposed alterations, changes, and extensions of the improvements, facilities, or services authorized herein; to locate, acquire, purchase, construct, alter, repair, maintain, and operate the improvements, facilities, and services authorized herein and enter into and execute contracts therefor; to obtain or prepare data for and determine rates, charges, and assessments to be imposed and collected for any improvements, facilities, and services authorized herein; to review and make adjustments of rates, charges, and assessments where the same are deemed excessive or inadequate; to engage consultants, assistants, attorneys, and employees; to act as the applicant, agents, or sponsor for the county in the borrowing or loaning of money, issuing of notes or bonds and receiving of any gift or grant of funds or property for the purposes authorized herein; to enter into and execute agreements with units of government, for the use of any such improvements, facilities, or services and the collection of rates, charges, and assessments; and to make all necessary rules governing the use and operation of such improvements, facilities, or services.
MCL 46.173