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Franklin Falls Dam Flood Risk Management Project

Franklin Falls DamFranklin Falls Dam in Franklin is located on the Pemigewasset River, which joins with the Winnipesaukee River about three miles downstream to form the Merrimack River. From Concord, it can be reached by taking U.S. Route 93 to Route 127 south, or U.S. Route 3 to Route 127 north.

Franklin Falls Dam is a key unit in the comprehensive plan of flood risk management for the Merrimack River Basin. It provides flood protection to communities along the entire length of the Merrimack River, including Franklin, Northfield, Boscawen, Canterbury, Concord, and Bow. Along with Blackwater Dam and the dams at Hopkinton and Everett Lakes, Franklin Falls Dam also reduces flooding in the principal industrial and residential centers on the Merrimack River, including Manchester and Nashua and the Massachusetts cities of Lowell, Lawrence, and Haverhill.

Construction of the project began in November 1939 and was completed in October 1943 at a cost of $7.9 million. The project has prevented $178.3 million in flood damages since it was built (as of September 2011).

The work involved:

  • Relocating a cemetery in Hill;
  • Moving several homes on the floodplain in Hill to other locations;
  • Demolishing several homes located on the floodplain in Hill; and
  • Relocating about nine miles of Route 3A.

The project consists of an earthfill dam with stone slope protection 1,740 feet long and 140 feet high; two gated horseshoe conduits, each 19 feet high, 22 feet wide, and 542 feet long; and a chute spillway founded on rock with a concrete weir 546 feet long. The weir’s crest elevation is 27 feet below the top of the dam.

Franklin Falls Dam has a permanent pool of 440 acres with a maximum depth of about seven feet. The flood storage area of the project totals 2,800 acres. This acreage extends about 12.5 miles upstream through the towns of Hill, Sanbornton, New Hampton, and Bristol, and ends at Ayers Island Dam in Bristol, which is owned by the Public Service Company of New Hampshire. The project and associated lands cover 3,683 acres. Franklin Falls Dam can store up to 50.2 billion gallons of water for flood control purposes. This is equivalent to 2.8 inches of water covering its drainage area of 1,000 square miles, which represents the largest drainage area upstream of the 35 dams built by the Corps’ New England Division.

There are two hydroelectric power plants upstream of Franklin Falls Dam, within the reservoir area, that are owned and operated by private interests. One plant, Salmon Brook Station, is situated at the Giles Pond Dam on Salmon Brook in Franklin, approximately .75 mile from Franklin Falls Dam. This facility was built on Corps land and produces 0.2 megawatts of power, which is sold to the Public Service Company of New Hampshire. The second plant, Newfound Hydroelectric, is situated at the Newfound Hydroelectric Dam on the Newfound River in Bristol, approximately 11 miles upstream of Franklin Falls Dam. This facility, which lies on private property but discharges within the Franklin Falls reservoir area, produces 1.5 megawatts of power, which is also sold to the Public Service Company of New Hampshire. A third hydroelectric power facility, Eastman Falls Station in Franklin, is at Eastman Falls Dam, about 1.5 miles downstream of Franklin Falls Dam. Situated on private property, Eastman Falls Station is owned by the Public Service Company of New Hampshire. The 440-acre permanent pool behind Franklin Falls Dam is created by the backwaters of the Eastman Falls Dam, which requires this pool to generate power.

The Reservoir Regulation Team (RRT) is the "nerve center" for the New England flood control dams such as Franklin Falls Dam. Using radio and satellite communications, the team constantly monitors river levels and weather conditions that influence flood control decisions.

The Reservoir Control Center provides information about river flows, dam operations, snow depths, recreational water releases, and more.

For more information, or for recreation opportunities, call (603) 934-2116 or visit the website at:

- Updated: May 4, 2021