Water resources inventory of Connecticut Part 4: Southwestern coastal river basins

The 44O square miles of the southwestern coastal river basins (394 square miles of which are in Connecticut) yield about 183 billion gallons, or 23.9 inches of runoff during an average year. This amount of runoff is almost entirely derived from precipitation falling on the basins, and is eventually discharged into Long Island Sound. In 1965, some streamflow originated from 5.5 billion gallons of water imported from the Housatonic River basin. Mean annual runoff is generally an index of the water potentially available for development; however, in the basins, large-scale impoundment and diversion of streamflow has preempted most of the surface water available.