 The largely industrialized cities of the Naugatuck River Valley were developed on each side of the river, with periodic sections of forested areas, before it enters the Housatonic River at Derby, at about above sea level.As part of the Housatonic River watershed, the Naugatuck River historically hosted the southernmost Atlantic salmon ("Salmo salar") migrations.Historical runs of anadromous fish also included native American shad ("Alosa sapidissima", Connecticut's state fish), alewife ("Alosa pseudoharengus") and blueback herring ("Alosa aestivalis").