Residents of the Mid-Atlantic states may know of Passaic Falls in New Jersey, Bushkill Falls (the "Niagara of Pennsylvania"), or the Great Falls of the Potomac in Maryland. Yet there are many other falls that are less known, just beyond the view from the highway. Some thunder awesomely, others are gossamer trickles. And, surprisingly, some are in the heart of the region's biggest cities. These natural water wonders are for the most part on public...