Surface water

In Massachusetts, the drainage area of the Quinebaug River is about 154 mi2, and that of the French River is about 95 mi2. These areas contain the headwater streams of Shetucket River, which is one of two major tributaries of the Thames River in Connecticut. The Quinebaug River basin contains 54 lakes and ponds, 31 of which have an area of 10 acres or more. The largest lake is East Brimfield Reservoir in Brimfield and Sturbridge, which is 420 acres. The French River basin contains 67 lakes and ponds, 38 of which cover at least 10 acres. Only one lake in this basin, Webster Lake (Lake Chabunagungamaug) in Webster (1,195 acres), is larger than 500 acres.

The Quinebaug River begins at an unnamed pond near Mashapaug Pond in Union, Conn., flows northward into Massachusetts, and then 75 mi southeastward and southward to its confluence with the Shetucket River. The Quinebaug River has a moderate slope of about 13 ft/mi from the headwaters area to the USGS streamflow-gaging station near the Massachusetts border in Quinebaug, Conn., a distance of about 29 river mi. The French River begins near Leicester, Mass., and flows southward to its confluence with the Quinebaug River in northeastern Connecticut. Together, the average daily discharge of the French and Quinebaug Rivers at the State line with Connecticut is about 300 Mgal.