The select and common councils of cities of the first class, be and they are hereby authorized, from time to time, to revise and establish the line beyond which no wharf or pier shall extend, and also to revise and establish the arbitrary low-water line or bulk-head line, on the Delaware river, in front of cities of the first class, in conformity with those now established by the secretary of war or as they may, from time to time be established by him during the progress of the work of the improvement of the harbors of said cities.
53 P.S. § 14216