(1) An authority created on or after May 1, 1984 shall within 2 years after its creation prepare or cause to be prepared a plan for the future development, construction, and improvement of the port and its facilities, including the maps, profiles, and other data and descriptions necessary to set forth the location and character of the work to be undertaken by the authority. An authority in existence before May 1, 1984 shall prepare or cause to be prepared the plan provided for in this subsection not later than September 30, 1985. The authority shall notify the legislature on April 15, 1985, as to the progress of the plan. The authority shall cause notice by publication to be given upon the completion of the plan in a daily newspaper of general circulation in the area under the jurisdiction of the authority. The notice shall fix the time and place for hearing on the plan, which shall be not less than 30 nor more than 60 days after publication of the notice. Any interested person may file written comments to the plan, if those comments are filed with the secretary-treasurer of the authority not less than 5 days before the date fixed for the hearing. After the hearing, the authority may adopt the plan, with any modifications or amendments, as the official plan of the authority. The authority, after adoption of the plan, may modify, amend, or extend the plan after notice and hearing in the manner prescribed in this subsection.

  (2) The plan and any modification, amendment, or extension, when adopted by the authority after notice and hearing, shall be conclusive except that plans for specific projects, to be undertaken in execution of the official plan, shall not be adopted by the authority without prior individual approval by the governing bodies of its constituent units, the state transportation department, and the department of commerce.