Nothing in this subchapter shall diminish any existing (as of March 1, 1975) rights-of-way or easements which are necessary for high voltage electrical transmission, pipelines, water mains, or line haul railroad operations and maintenance. Nothing in this subchapter shall be construed to diminish the existing property rights of Northern Indiana Public Service Company (as of October 1, 1986) with respect to—

(1) a parcel of land owned in fee by the Northern Indiana Public Service Company and used for high voltage electrical transmission lines, pipelines, and utility purposes, beginning at said Company’s Dune Acres substation and extending east to said Company’s Michigan City Generating Station, which parcel by this subchapter is included within the boundaries of the Indiana Dunes National Park and herein designated as area II-I on National Park Service Boundary Map No. 626-80,033-B, dated October 1986, excluding that certain parcel of approximately 6.0 acres adjacent Mineral Springs Road in areas II-I, and

(2) land owned in fee by the Northern Indiana Public Service Company and used for high voltage electrical transmission lines, pipelines, and utility purposes as has by this subchapter been included within the boundaries of the Indiana Dunes National Park and herein designated as area II-H on said National Park Service Boundary Map No. 626-80,033-B.