General management plans for the preservation and use of each System unit, including areas within the national capital area, shall be prepared and revised in a timely manner by the Director. On January 1 of each year, the Secretary shall submit to Congress a list indicating the current status of completion or revision of general management plans for each System unit. General management plans for each System unit shall include—
((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 System unit; and
((4)) indications of potential modifications to the external boundaries of the System unit, and the reasons for the modifications.