The EPA subsequently listed the town as a toxic site and led a cleanup effort to repair the damage.

The Sudbury River starts at Cedar Swamp Pond in a swampy area in Westborough and flows northeast 32.7 miles (52.6 km), starting at an elevation of 327 feet (100 m) and descending through the towns of Westborough, Hopkinton, Southborough, Ashland, Framingham, Wayland, Sudbury, Lincoln and finally Concord, where it merges (42.4653°N 71.3584°W) with the Assabet River at Egg Rock to form the beginning of the Concord River, at an elevation of 100 ft (30 m).

The average flow rate for 37 years of complete data (1981–2016) is 201 cubic feet per second (cfs).

Any time depth exceeds 13.0 feet the river is considered to be in major flood status.

The infestation on the Sudbury River is particularly bad between the Fenwick Street and Saxonville dams, where the water surface can be more than 80% covered.

[5] For those interested in renting, the South Bridge Boat House, on Route 62 west of the center of Concord offers "Rent a canoe or kayak and explore miles of peaceful waterways on the Assabet, Sudbury and Concord Rivers.