((a)) **   —** To protect the air, land, water, and natural and cultural values of the System and the property of the United States in the System, no solid waste disposal site (including any site for the disposal of domestic or industrial solid waste) may be operated within the boundary of any System unit, other than—

((1)) a site that was operating as of ; or

((2)) a site used only for disposal of waste generated within that System unit so long as the site will not degrade any of the natural or cultural resources of the System unit.

((b)) ** .—** The Secretary shall prescribe regulations to carry out this section, including reasonable regulations to mitigate the adverse effects of solid waste disposal sites in operation as of , on property of the United States.