The Black River is a blackwater river that empties into the eastern end of Lake Ontario on the shore of Jefferson County, New York in the United States. The origin of the name is not clear, but it may stem from the natural tannic acid that darkens the water in places. The river flows in a generally northwest direction, with its valley dividing the Adirondack Mountains on the east from the Tug Hill region to the west. Course The Black River originates at North Lake in the foothills of the Adirondacks, in Herkimer County, about east of Boonville. The river flows west into Oneida County then north, past Forestport and Boonville into Lewis County. At Lyons Falls, it is joined by the Moose River from the east just above the eponymous waterfall, where the river drops over a gneiss cliff. Near Glenfield the Black River receives the smaller tributaries of Otter Creek and the Independence River, also from the east. Further north, it passes Lowville, then receives the Beaver River from the east, then the Deer River, its only major western tributary. Starting above Carthage the river briefly divides Lewis and Jefferson Counties before crossing entirely into Jefferson County, where it turns sharply west toward Lake Ontario, flowing past Great Bend, Black River and Watertown. Below Watertown it enters a canyon, well known for its challenging rapids. The river ends at Lake Ontario in the village of Dexter, about west of Watertown, where it empties into the Black River Bay and Marsh, which are parts of the Golden Crescent. For the last few miles it forms the boundary between the Towns of Brownville and Hounsfield. Dams There are at least 17 dams on the Black River, with eight in the upper part above Lyons Falls, and nine below Watertown. The upper and lower reaches of the river have a steep gradient and were originally developed to provide mechanical power for mills, such as the old Georgia-Pacific paper mill (which now sits abandoned and falling into disrepair) in Lyons Falls, and later hydroelectricity. In contrast the middle of the river have practically no gradient and are not suitable to the development of head for industrial or hydropower projects. The three uppermost dams, forming North Lake, Kayuta Lake and the smaller Forestport Reservoir are the only structures forming significant impoundments. The other dams are run-of-the-river, with no appreciable storage capacity, so power