53 Pa. Stat. § 14203
The directors of the Department of Wharves, Docks and Ferries, in any city of the first class, shall have authority, after the appropriation by councils, or said city, or by the Commonwealth of Pennsylvania, of the money required therefor, to erect and construct retaining structures adjoining the banks of navigable streams located within its corporate limits, for the purpose of protecting the channel of such streams; and when any such retaining structure shall have been erected or constructed the cost thereof per foot shall be filed in the office of said director, and no riparian owner, lessee or licensee, shall use any such retaining structure for the purpose of constructing, extending, altering, improving or repairing, any wharf, or other building in the nature of a wharf, or other harbor structure, or for other wharf purposes, without having previously paid to the said director of the city in which such retaining structure is erected or constructed the cost of erecting so much of said retaining structure as is so used; and any such person who shall use any such retaining structure as aforesaid, before the cost thereof has been paid to the said director as aforesaid, shall pay to the said city a penalty of twenty-five dollars per day for every day on which such retaining structure shall be so used, to be collected as debts of a similar nature are now collected. All money paid to the director under the provisions of this act shall be paid by him into the city treasury, to be used by the said city, only for the purpose of developing, extending, and improving the wharves owned by the said city.
53 P.S. § 14203