The Manhan River is a 27.6-mile-long (44.4 km) river in western Massachusetts. It is a tributary of the Connecticut River.The river begins near the boundary between the towns of Huntington and Westhampton, Massachusetts, and flows southeast to White Reservoir and then Tighe Carmody Reservoir in Southampton. The river continues southeast, then turns northeasterly and flows through the middle of Easthampton to its confluence with the Connecticut River at a westward curve called The Oxbow.