When the United States of America shall acquire by purchase, condemnation or otherwise any or all of the real estate belonging to the Monongahela navigation company, consisting of locks, dams, abutments, lockhouses or other real estate used in connection with the slack-water improvements on the Monongahela river, the Commonwealth of Pennsylvania hereby cedes to the government of the United States jurisdiction over the said real estate so acquired.
74 P.S. § 21