<Tr> <Th> Basin </Th> <Td> 602 sq mi (1,559 km) </Td> </Tr> <P> The Farmington River is a river, 46.7 miles (75.2 km) in length along its main stem, which is located in northwest Connecticut with major tributaries extending into southwest Massachusetts . Via its longest branch (the West Branch), the Farmington's length increases to 80.4 miles (129.4 km), making it the Connecticut River's longest tributary by a mere 2.3 miles (3.7 km) over the major river directly to its north, the Westfield River . The Farmington River's watershed covers 609 square miles (1,580 km). The river historically played an important role in small - scale manufacturing in towns along its course, but it is now mainly used for recreation and drinking water . The Farmington River Watershed Association is a non-profit organization for conservation and preservation of this river . </P> <P> Headwaters for both main branches of the Farmington River, referred to as the East Branch and West Branch, are found in southwestern Massachusetts, though only the West Branch officially begins north of the Connecticut border . The West Branch rises at the outlet of Hayden Pond in Otis, Massachusetts . In 1994, a 14 - mile (23 km) stretch of the branch was designated a National Wild and Scenic River . The East Branch begins in Hartland, Connecticut at the confluence of Pond, Hubbard and Valley Brooks . However, this branch has been impounded along the first 11 miles of its course to form the Barkhamsted Reservoir and Lake McDonough; it does not assume a particularly river - like appearance until it exits Lake McDonough in New Hartford, Connecticut . The East Branch and West Branch join in New Hartford, Connecticut just about one mile south of Lake McDonough . Upper reaches of the river flow mostly southward, but the river turns northward in Farmington, Connecticut and then runs mostly north and east until it flows into the Connecticut River near the Loomis Chaffee School in Windsor, Connecticut . </P> <P> There are several whitewater sections . One of these, the so - called "Upper Farmington" section of the West Branch in New Boston, Massachusetts, is about 7 miles (11 km) long . It is Class 2 through farm and woods scenery to an iron bridge, where kayak and canoe slalom races are held . Below the bridge the river becomes Class 3 - 4, very technical at low water, and technical and pushy at higher water, with a short gorge with several abrupt drops . </P>

Where does the farmington river start and end
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