The Department of Playground and Recreation is authorized to construct, maintain and operate groins, jetties, breakwaters, seawalls, pipe lines, and other work or structures, for the purpose of protecting public beach properties in the City and for the purpose of creating additional beach areas, and is further authorized to construct, maintain and operate piers, wharves, bath houses, lifesaving stations and equipment or other structures for recreation purposes upon, along or out from any beach properties owned or controlled, now or hereafter, by the City, provided the same do not interfere with the use of the waters of the Pacific Ocean for the purpose of commerce, navigation and fishery.