Ashuelot River

The Ashuelot River is a tributary of the Connecticut River in southwestern New Hampshire. It runs about 64 miles and is the longest Connecticut River tributary within the state. It rises at Butterfield Pond in Pillsbury State Park near Washington and flows southwest through Ashuelot Pond. From there it runs south past Keene and Swanzey, then turns west at Winchester and joins the Connecticut at Hinsdale. Its watershed is roughly 415 to 425 square miles. The river is dammed for hydroelectricity at Marlow, Keene, Swanzey and Hinsdale. At Surry, the U.S. Army Corps of Engineers built Surry Mountain Dam in 1941 for flood control, forming the 353-acre Surry Mountain Lake. The river became a state designated river in June 1993.

Public carry-in sites on the lower river include Old Stone Arch Bridge (City of Keene), West Swanzey AA Memorial Park and Cresson Covered Bridge Access (Town of Swanzey), Winchester Village Dam Site (State), Ashuelot River Access (NHDOT) near Winchester, and Hinsdale Town Park. According to NHDES, small craft and motorboats use the ponded sections, while canoeists and kayakers paddle the flatwater, quickwater and whitewater reaches. These include Class II-III rapids between Gilsum Gorge and Surry and Class V rapids in Winchester. Several dams have been removed: Winchester Dam in 2002 and the 14-foot Homestead Woolen Mills Dam in Swanzey in 2010. The Nature Conservancy bought Hinsdale's 1922 Fiske Mill Dam, about 1.5 miles above the mouth, in 2022.

The river supports about 15 resident fish species, including brook trout, largemouth and smallmouth bass, and walleye. Walleye, bass, bullheads and perch are the main catch near the Connecticut River confluence.