Where any lands included within the boundary of the monument on the map referred to in subsection ¹ 460uu(a) of this title are legally occupied or utilized on December 31, 1987, for grazing purposes, pursuant to a lease, permit, or license which is—

(a) for a fixed term of years issued or authorized by any department, establishment, or agency of the United States, and

(b) scheduled for termination before December 31, 1997,

the Secretary, notwithstanding any other provision of law, shall allow the persons holding such grazing privileges (or their heirs) to retain such grazing privileges until December 31, 1997, subject to such limitations, conditions, or regulations as the Secretary may prescribe to insure proper range management. No grazing shall be permitted on lands within the boundaries of the monument on or after January 1, 1998.