The Seneca River flows through the Finger Lakes region of Upstate New York in the United States. The main tributary of the Oswego River – the second largest river flowing into Lake Ontario – the Seneca drains in parts of fourteen New York counties. The Seneca flows generally east, and is wide and deep with a gentle gradient. Much of the river has been channelized to form part of the Erie Canal. Geography The Seneca River begins at Geneva in Seneca County, as the outflow of Seneca Lake, flowing east past Waterloo and Seneca Falls. Skirting the northern end of Cayuga Lake at the Montezuma Marsh, it turns north, receiving the Clyde River from the west, forming the Seneca–Cayuga county line, then the border of Cayuga and Wayne counties. The river passes under Interstate 90, flowing northeast past Weedsport, across the middle of Cayuga County into Cross Lake. Below Cross Lake the Seneca River enters Onondaga County. It turns sharply north then east, past Baldwinsville and Liverpool, along the northern edge of metro Syracuse where it receives the outflow of Onondaga Lake. The river then flows north to join the Oneida River at Three Rivers on the Onondaga–Oswego County line, forming the Oswego River. From the confluence, the Oswego flows a further north, emptying into Lake Ontario at the city of Oswego. The Seneca River watershed drains a total of , or about two-thirds of the greater Oswego River basin. There are about of streams in the Seneca basin. The Seneca receives the outflow of seven of the eleven Finger Lakes: Canandaigua, Keuka, Seneca, Cayuga, Owasco, Skaneateles and Otisco. Canandaigua Lake flows via the Canandaigua Outlet and the Clyde River into the Seneca River. Keuka Lake empties into Seneca Lake via the Keuka Lake Outlet. Owasco and Skaneateles Lakes join the Seneca through their eponymous outlet streams, while Otisco Lake flows via Ninemile Creek into Onondaga Lake, which in turn empties into the Seneca. Tributaries Left Black Brook Clyde River Crusoe Creek Spring Lake Outlet Muskrat Creek Right Kendig Creek Silver Creek Sucker Brook Sampson Creek Demont Creek Cayuga Lake Crane Brook Owasco River Skaneateles Creek Dead Creek Crooked Brook Onondaga Lake History Native Americans The river is named for the Seneca people, whose traditional lands extended roughly between Lake Erie and Seneca Lake. The Onondaga inhabited the area in present-day Onondaga County, around Onondaga Lake and Syracuse, and the