The Department of Transportation shall, in a manner consistent with the Maine Administrative Procedure Act, Title 5, chapter 375, establish tolls for the use of such ferry line or lines by vehicles, freight and passengers. Tolls collected from the operation of the Maine State Ferry Service shall at all times be kept in a separate fund distinct from all other moneys of the State and shall be used for the operation and debt retirement of the ferry service.   [PL 1981, c. 456, Pt. A, §88 (NEW).]