The dock board is also vested with exclusive regulation and control of the harbor and the waterfront within or abutting upon the territorial limits of such county or municipality, consistent with the laws of the United States governing navigation, and may make reasonable rules and regulations governing the traffic and use thereof, and to promote the sanitary condition of said harbor and waterfront and to prevent the pollution of the waters within said harbor and governing the use and improvement of riparian land, and structures thereon, within and abutting upon the territorial limits of such county or municipality.