Any powers granted to the commission shall be regarded as in aid of and supplemental to, and in no case a limitation upon, any of the powers vested in the commission by other laws of this Commonwealth, or by the laws of the States of Maine, New Hampshire, Massachusetts, Connecticut, Rhode Island, New York, New Jersey, Delaware, Maryland, Virginia, North Carolina, South Carolina, Georgia and Florida, or by the Congress of the United States or the terms of said compact.