If the Secretary of the Army, acting through the Chief of Engineers, finds that the proposed project to be erected at the location to be declared non-navigable under this section is in the public interest, on the basis of engineering studies to determine the location and structural stability of the bulkheading and filling and permanent pile-supported structures in order to preserve and maintain the remaining navigable waterway and on the basis of environmental studies conducted pursuant to the National Environmental Policy Act of 1969 [42 U.S.C. 4321 et seq.], then those portions of the East River in New York County, State of New York, bounded and described as follows are hereby declared to be not navigable waters of the United States within the meaning of the laws of the United States, and the consent of Congress is hereby given to the filling in of all or any part thereof or the erection of permanent pile-supported structures thereon: That portion of the East River in New York County, State of New York, lying shoreward of a line with the United States pierhead line as it exists on March 7, 1974, bounded on the north by the south side of Rutgers Slip extended easterly, and bounded on the south by the southeasterly border of Battery Park at a point adjacent to the westerly end of South Street extended south by southwest, is hereby declared to be non-navigable waters of the United States. This declaration shall apply only to portions of the above-described area which are bulkheaded and filled or occupied by permanent pile-supported structures. Plans for bulkheading and filling and permanent pile-supported structures shall be approved by the Secretary of the Army, acting through the Chief of Engineers. Local interests shall reimburse the Federal Government for engineering and all other costs incurred under this section.