The commissioners shall have power to make surveys and soundings to ascertain the capacities of the aforesaid river and its navigable tributaries for commercial purposes, and to prepare plans therefrom, and to keep records thereof. They shall also have power to regulate, fix, and establish bulkhead and pierhead lines, and the distance between piers, subject to the regulation of the United States Government; to adopt and promulgate rules and regulations for the construction, extension, alteration, improvement, and repair of wharves, piers, bulkheads, docks, slips, and basins: Provided, That, for the purposes of this section, the commissioners shall not have jurisdiction within any city of the first class.