The Farmington River is a river located in northwest Connecticut, with major tributaries extending into southwest Massachusetts. Via its longest branch (the West Branch), the Farmington's length increases to , making it the Connecticut River's longest tributary by a mere over the major river directly to its north, the Westfield River. The Farmington River's watershed covers . The river historically played an important role in small-scale manufacturing in towns alongside it, 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.