Nothing herein contained shall affect any valid existing claim, location, or entry established prior to July 3, 1926, under the land laws of the United States, whether for homestead, mineral, right-of-way, or any other purpose whatsoever, or shall affect the rights of any such claimant, locator, or entryman to the full use and enjoyment of his land: Provided, That under rules and regulations to be prescribed by him the Secretary of the Interior may issue permits to any bona fide claimant, entryman, landowner, or lessee of land within the boundaries herein established to secure timber for use on and for the improvement of his land; and he shall also have authority to issue, under rules and regulations to be prescribed by him, grazing permits and authorize the grazing of livestock on the lands within said park at fees not to exceed those charged by the Forest Service on adjacent areas, so long as such timber cutting and grazing are not detrimental to the primary purpose for which such park is created: Provided, That no permit, license, lease, or authorization for dams, conduits, reservoirs, power houses, transmission lines, or other works for storage or carriage of water, or for the development, transmission, or utilization of power within the limits of said park as constituted by said sections, shall be granted or made without specific authority of Congress.