All lands, rights in lands, rights of way, and water courses acquired under the authority of this act for State or Federal flood control works and improvements, shall be acquired without cost to the United States, and no moneys made available for flood control in this Commonwealth, by the United States, shall be used for such purposes unless in either event the Government of the United States, or any of its agencies or instrumentalities, shall first consent thereto, nor shall the Government of the United States be deemed liable for any damages, by reason of its contribution, arising in connection with the construction of any State or Federal public works or improvements. The Commonwealth hereby agrees that after such State public works and improvements are constructed where the Federal Government has contributed, the same will be operated and maintained in accordance with all rules and regulations prescribed by the Secretary of War¹ of the United States, subject to all the limitations imposed by this act.