The Housatonic River is a river, approximately 149 mi (240 km) long, in western Massachusetts and western Connecticut in the United States. It flows south to southeast, and drains about of southwestern New England into Long Island Sound. Its watershed is just to the west of the watershed of the lower Connecticut River.
The river's total fall is 1430 feet (959 feet from the confluence of its east and west branches). Its major tributaries are the Williams, Green and Konkapot Rivers in Massachusetts, the Tenmile River in New York, and the Shepaug, Pomperaug, Naugatuck, and Still Rivers in Connecticut. It receives the Naugatuck River at Derby, Connecticut, and the Still River south of New Milford, Connecticut.
Five dams impounded the river in Connecticut to produce hydroelectricity, the Falls Village, Bulls Bridge, Shepaug, Stevenson and Derby dams. The last three dams form a chain of lakes, Candlewood Lake, Lake Lillinonah, Lake Zoar and Lake Housatonic, from New Milford south to Shelton.
Inspired by the river during his honeymoon, the American classical music composer Charles Ives wrote The Housatonic at Stockbridge as part of his composition Three Places in New England during the 1910s. The town of Stockbridge is located in southwestern Massachusetts. The river enters Stockbridge on the east side of town then turns south towards Connecticut.
From about 1932 until 1977 the river received PCB pollution from the General Electric plant at Pittsfield, Massachusetts. Although the water quality has improved in recent decades, the river continues to be contaminated by PCBs.
The United States Navy named a ship for the Housatonic river. The USS Housatonic has the distinction of being the first ship in history to be sunk by a submarine, the confederate vessel CSS H.L. Hunley.
The Housatonic River is also a popular fly fishing destination. Fly fishing on the Housatonic River has been compared with many western rivers and boasts some of the finest trophy trout fishing in the eastern United States. The most popular area for fly fishing is between the Falls Village Dam and the town of Cornwall Bridge in Litchfield County.