The Naugatuck River is a 40.2-mile-long (64.7 km) river in the U.S. state of Connecticut. Its waters carve out the Naugatuck River Valley in the western reaches of the state, flowing generally due south and eventually emptying into the Housatonic River at Derby, Connecticut and thence 11 miles (18 km) to Long Island Sound. The Plume and Atwood Dam in Thomaston, completed in 1960 following the Great Flood of 1955, creates a reservoir on the river and is the last barrier to salmon and trout migrating up from the sea.