All lands acquired pursuant to this subchapter shall be taken by the Secretary subject to all valid existing rights granted by the United States for railroad, telephone, telegraph, and pipeline purposes. The Secretary is authorized to grant rights-of-way, easements, permits, and other benefits in, through and upon all lands acquired for the White Pass Trail unit for pipeline purposes, pursuant to the Acts of February 25, 1920 (
41 Stat. 449), August 21, 1935 (
49 Stat. 678), and August 12, 1953 (
67 Stat. 557), and for railroad purposes pursuant to the Act of May 14, 1898 (
30 Stat. 409): Provided, That significant adverse impacts to park resources will not result.