Mich. Comp. Laws § 120.22: Lease of property; maximum term, bond.

Sec. 22.

Each port commission shall have power to lease under such covenants and conditions as the commission may prescribe, all storage facilities, wharves, piers, bulkheads, docks, sheds, warehouses, industrial locations and other property owned and controlled by said port district upon such terms as the port commission may deem proper: Provided, That no lease shall be executed for longer than a period of 50 years and every such lease shall be secured by a bond with surety satisfactory to or approved by the port commission.