USACE CWMS - Thames Watershed

The Corps Water Management System (CWMS) includes four interrelated models to assist with water management for the basin:
- GeoHMS (Geospatial Hydrologic Modeling Extension)
- ResSIM (Reservoir System Simulation)
- RAS (River Analysis System)
- FIA (Flood Impact Analysis)
The Thames River Basin is located within the states of
Connecticut, Massachusetts and Rhode Island. Of the 1,474 square miles that make up the basin, 1,162
square miles, or 79% of the basin, extends into Connecticut. About 17% of the basin is located in
Massachusetts and the remaining 4% in Rhode Island. The basin is characterized by a hilly terrain
comprised of lakes, ponds and several reservoirs. Elevations within the Thames River Basin range from
600 feet to about 1200 feet above mean sea level in the northwest.
The coastal location of the Thames River basin exposes it to the effects of cyclonic disturbances and
coastal storms in the region, resulting in periods of heavy precipitation. On an average, this basin
receives approximately 46 inches of precipitation annually. The average annual snowfall in Groton,
Connecticut is about 25 inches, which is representative of the coastal regions of the Thames River
Basin. Within the upper Quinebaug River watershed, the average annual snowfall ranges from 54 to 65
inches.
The Thames River basin derives its name from Thames River, which is a 15 mile long tidal estuary
extending from the confluence of the Shetucket and Yantic Rivers near Norwich, CT to Long Island
Sound at New London, CT. Some of its major tributaries include the French River, Quinebaug River,
Yantic River, Shetucket River, Willimantic River, Natchaug River and Mt. Hope River. Of these, the
Quinebaug and French Rivers have their origins in Massachusetts.
The key inflow gages in the Thames River basin include Yantic River at Yantic, Natchaug River at
Willimantic, Shetucket River Near Willimantic, Little River Near Oxford, French River Below Dam at
Hodges Village and Quinebaug River Below East Brimfield Dam At Fiskdale.
There are six USACE dams located within the Thames River Basin. They include the Mansfield Hollow
Dam on the Natchaug River, Buffumville Dam on Little River, Hodges Village Dam on French River and
East Brimfield Dam, Westville Dam and West Thompson Dam on Quinebaug River. Mansfield Hollow
Dam primarily serves the purpose of flood protection for the community of Willimantic located
immediately below the dam. Similarly, other dams primarily provide flood protection to downstream
communities – Buffumville Lake and Hodges Village dams to the town of Oxford, East Brimfield Dam to
the town of Sturbridge, Westville Dam to the town of Southbridge and West Thompson Dam to the town
of Putnam.
The Thames River basin is one of the most rural basins in the New England Region, with majority of the
land use characterized by agriculture, forest land and open space. Dairy, poultry operations and truck
farming form the major agriculture businesses. Major manufacturing industries within the basin include
textiles, lumber, machinery and fabricated metals. While wholesale and retail trade industries have seen
an increase in employment in recent years, agriculture, forestry and fisheries have continued to decline
steadily.