|Cities||Thompson, Putnam, Killingly|
|- location||Thompson, Windham County, Connecticut, United States|
|- elevation||480 ft (150 m)|
|Mouth||Empties into Quinebaug River|
|Danielson, Windham County, Connecticut, United States|
|185 ft (56 m)|
|Length||23.5 mi (37.8 km)|
|- location||Danielson, CT|
The Fivemile River is a 23.5-mile-long (37.8 km) river located in Connecticut's Northeast Corner and flows through the towns of Thompson, Putnam, and Killingly.The original Nipmuc name was Assawaga, meaning "place between" or "halfway place". The Assawaga received its English name from the fact that the first land laid out upon it was "supposed to be about five miles from" Woodstock, Connecticut. The Five Mile is a tributary of the Quinebaug River and is part of the Thames River watershed. Its source is Little Pond (also known as Schoolhouse Pond), close to the Massachusetts border. It empties into the Quinebaug River at Danielson, near the intersection of Connecticut Route 12 and U.S. Route 6.
The Fivemile River has several dams, most of which are former mill operations. Its largest impoundment is Quaddick Reservoir, though there are several smaller dams including those that were built for the purpose of harnessing waterpower for industry. The best examples of surviving mill villages can be seen in Killingly in villages such as Pineville, Ballouville, Attawaugan, and Dayville.
- Killingly, Windham County, Connecticut History
- Environmental Protection Agency
- Connecticut Department of Environmental Protection