Mich. Comp. Laws § 486.7
For the purpose of defraying the expenses of such repairing, rebuilding or permanent improvement, and such contingent expenses as may be incurred in the discharge of their duties as directors of such association, the said directors may make from time to time, as the work progresses, an assessment upon the owners of such water-power, assessing and apportioning to and upon each owner thereof, such portion of said expenses as the water-power used or owned by such persons bears to the whole water-power furnished by such canal and its appurtenances; and when a water-power afforded by such canal is owned by a firm or corporation, such firm or corporation shall be considered as an individual member, and such assessment may be made to and upon such firm or corporation.
MCL 486.7