53 Pa. Stat. § 14200
If any person or persons shall construct, alter, or improve any wharf or building or harbor structure, as aforesaid, within the limits of said cities, beyond low-water mark, without license or an order of court, as hereinafter provided, first having been obtained, such wharf or building or harbor structure shall be deemed a public or common nuisance, and such person or persons shall be guilty of maintaining a nuisance, and, upon conviction, shall be sentenced to pay a fine of five hundred dollars, or suffer an imprisonment of six months, or either, or both, according to the discretion of the court; and, where the said nuisance shall be in existence at the time of the conviction and sentence, it shall be lawful for the court, in its discretion, to direct either the defendant, or sheriff of the proper county, at the expense of the defendant, to abate the same: Provided, That in all cases where any license or order has been or shall be given or made, permitting the erection, construction, extension, alteration, or improvement of any wharf, building, or harbor structure, aforesaid, beyond low-water mark of the waterways, or any harbor structure, within the limits of said cities, the person or persons to whom such license or order has been or shall be granted shall, within six months from the date of said license or order, commence the work for which such license or order shall have been granted, and shall prosecute such work with due diligence to completion; otherwise said license or order shall become void: Provided, further, That all licenses granted or orders made for the erection, construction, extension, alteration, or improvement, aforesaid, prior to the passage of this act, shall be and become void within six months after this act shall take effect, unless said work shall have been begun thereon and shall be prosecuted with due diligence to completion.
53 P.S. § 14200