Winters Run is a 14.6-mile-long (23.5 km) river in Harford County, Maryland. The river begins north of the community of Fallston at the confluence of the West and East Branches, and flows southeast about 11 miles (18 km) to Atkisson Dam in Edgewood. The dam and reservoir were built by the U.S. Army in 1942 to provide an auxiliary fresh water source for nearby Edgewood Arsenal. Upon reaching the tidal line, the river is renamed Otter Point Creek, which empties to Bush River and the Chesapeake Bay.