Lower Sudbury River

The Sudbury River flows northeast from Cedar Swamp in Westborough to its confluence with the Assabet River in Concord. The Lower Sudbury segment starts at the outlet of Stearns Reservoir (Reservoir #1) in Framingham and runs to the confluence in Concord. A large portion of this segment—from just below the Saxonville dam in Framingham to the confluence—together with contiguous sections of the Sudbury and Concord Rivers, was federally designated in 1999 as a Wild & Scenic River, reflecting its natural beauty and free-flowing condition. Much of the segment in Sudbury, Wayland, and Concord is in the Great Meadows National Wildlife Refuge managed by the US Fish and Wildlife Service. It is a very popular destination for warmwater fishing, wildlife viewing, and boating.

The Lower Sudbury River received an Overall grade of B. The river has relatively good water quality and receives relatively little wastewater discharge. The contamination of fish by mercury from the Nyanza Superfund site upstream in Ashland resulted in a grade of F for the Fish Edibility indicator. Several upstream dams, the largest controlled as part of the MWRA metropolitan Boston water supply system, alter the natural streamflow, and this along with other factors result in a grade of D for the Streamflow Alteration indicator.