The Watertown Dam spans the Charles River 980 feet (300 m) upstream from the Watertown Bridge near Watertown Square in Watertown, Massachusetts. The dam is located where the Charles River tidal estuary historically ended (the tides no longer reach this point because of the downstream Charles River Dam). Watertown Dam is of earthen construction, a gravity dam. Its length is 220 feet (67 m). Its capacity is 30 acre feet (37,000 m³). Normal storage is 20 acre feet (25,000 m³).