Within three years from November 10, 1978, the Secretary shall develop and transmit to the Senate Committee on Energy and Natural Resources and the House Committee on Interior and Insular Affairs, a general management plan for the protection and development of the national river consistent with the purposes of this subchapter, indicating—

(1) measures for the preservation of the area's resources;

(2) indications of types and general intensities of development (including visitor circulation and transportation patterns, systems and modes) associated with public enjoyment and use of the area, including general locations, timing of implementation, and anticipated costs;

(3) identification of and implementation commitments for visitor carrying capacities for all areas of the unit; and

(4) indications of potential modifications to the external boundaries of the unit, and the reasons therefor.