Nothing in this subchapter shall be construed as affecting in any way any rights of owners and operators of cattle and sheep herds, existing on the date immediately prior to , to trail their herds on traditional courses used by them prior to , and to water their stock, notwithstanding the fact that the lands involving such trails and watering are situated within the park: , That the Secretary may designate driveways and promulgate reasonable regulations providing for the use of such driveways.November 12, 19711971-11-12November 12, 19711971-11-12Provided