The Sudbury River flows from Cedar Swamp in Westborough northeast 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, and 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).
The Upper Sudbury River received an Overall grade of C. The Upper Sudbury received a grade of D for Streamflow Alteration, reflecting the dry riverbed in Hopkinton during droughts and manipulation of flow at the reservoir dams. There is a dearth of water quality data for the Upper Sudbury and the Scenic Assessment has not yet been carried out. The Recreation grade of D- provides an opportunity to raise the grade through improving public access and passage around dams.