The Sudbury River flows northeast from Cedar Swamp in Westborough to its confluence with the Assabet River in Concord. The Upper Sudbury segment starts at Cedar Swamp, a state-designated Area of Critical Environmental Concern, and ends at the outlet of Stearns Reservoir (Reservoir #1) in Framingham. There are several old mill dams along its length. The dams containing the Bracket and Stearns Reservoirs, formerly part of Boston’s water supply, are managed by the Massachusetts Water Resources Authority (MWRA) and the Department of Conservation and Recreation (DCR).
