Mich. Comp. Laws § 120.35

Sec. 35. This act shall not be construed to repeal, amend, or modify any law heretofore enacted, providing a method of harbor improvement, regulation or control in this state, but shall be held to be an additional and concurrent method providing for such purpose and except by agreement between the port commission and the parties at interest, shall not be construed to include within its terms any property now or hereafter devoted to public use, owned, operated or controlled by any person, municipality or private corporation.