Fast Facts

Here are some facts about the Upper Connecticut River and its watershed. For more, explore our web site and its extensive links.
length ~ depth ~ watershed ~elevation~ towns ~ state boundary ~ flow ~ dams ~ tributaries ~ water quality ~ shoreland protection ~ special designations


The Connecticut River is the largest river in New England. It flows 410 miles from its source at Fourth Connecticut Lake, a tiny beaver pond 300 yards from the Canadian border, to Long Island Sound. New Hampshire and Vermont share some two thirds of the river's length, or 275 miles.


The river's depth varies from a few inches to 130' deep just below the French King Bridge in Gill, Massachusetts. The depth of the river in most places is constantly changing as the river transports and rearranges its load of sediment.


The Connecticut River drains 4.5 million acres, or 7,000 square miles, of New Hampshire and Vermont. This amounts to 63% of the whole four-state watershed (which is 11,250 square miles, or 7.2 million acres). The watershed is a long basin lying between the spines of the Green Mountains of Vermont and the White Mountains of New Hampshire. The river's watershed includes 41% of Vermont's total land area, 33% of New Hampshire's, and also a very small part of Quebec, in the Hall Stream basin.


The Connecticut River rises a few hundred yards south of the Canadian border at Fourth Connecticut Lake, at an elevation of 2,670 feet above sea level. It drops half of that elevation before it ever leaves the town of Pittsburg. By the time the river reaches the Massachusetts line, it has fallen to approximately 190 feet above sea level.


Lying within the upper Connecticut River's watershed are 114 Vermont towns and 93 New Hampshire towns. Fifty-three towns border the river, 27 in Vermont and 26 in New Hampshire.

State boundary

The border between New Hampshire and Vermont was set by King George II in 1764 as the western bank of the Connecticut River. The U.S. Supreme Court re-affirmed this boundary in 1934 as the ordinary low-water mark on the Vermont shore, and markers were set. In some places, the state line is now inundated by the impoundments of dams built after this time.


In the Connecticut River, flows vary widely according to location, time of year, snow melt, precipitation, and management of dams. For more information, and links to US Geological Survey gages that give real time flow data, click here.


There are 13 existing dams on the mainstem of the upper Connecticut River, and two more that the river has breached. There are hundreds of smaller dams on tributaries throughout the watershed.


The Connecticut River is the sum of hundreds of tributaries, large and small. For more information about the major VT and NH tributaries, click here.

Water quality

The quality of the river's waters has greatly improved in the last 40 years. To learn more about the safety of the river for swimming, click here.

Shoreland protection

Shoreland on the NH side of the Connecticut River is protected by state law, which requires a 50 foot building setback and a 150 foot natural shoreland buffer, and in many towns by local zoning which is often more protective. While some VT towns have local zoning that protects their Connecticut River shoreland, there is no state protection for shorelands in Vermont.

Special designations

Congress created the Silvio O. Conte National Fish & Wildlife Refuge in 1991, encompassing the entire four-state watershed, with the Connecticut River as its centerpiece. The following year, NH General Court designated the Connecticut River into the New Hampshire Rivers Management and Protection Program. In 1998, the White House designated the Connecticut as an American Heritage River.