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Posted 7/20/2012

Release no. 2012-069

Tim Dugan

CONCORD, Mass. – The U.S. Army Corps of Engineers, New England District, the communities of Hopkinton, Henniker, Dunbarton, and Weare, along with several other agencies and groups will observe the 50th anniversary of the Hopkinton and Everett Dams in a ceremony on July 28, 2012 at the project office in Hopkinton, New Hampshire.


“This project is a great example of applied engineering and science successfully mitigating flood risk and damage, and adding immeasurable value to the region,” said District Engineer Col. Charles Samaris, commander of the Corps’ New England District. "These dams have protected downstream citizens in New Hampshire and Massachusetts for 50 years. They have proven to be a very successful investment of time and money, preventing more than $217 million in flood damages since their construction."


The dam at Hopkinton Lake, on the Contoocook River in Hopkinton, and the dam at Everett Lake, on the Piscataquog River in Weare, are connected by a two-mile long canal and in moderate to severe flooding are operated as a single flood risk management project. Construction of the dual facility was completed in 1962 at a cost of $21.4 million.


A ceremony to observe the 50th anniversary of the completion of the dams will be held on Saturday, July 28, 2012 at the project office at 2097 Maple Street in Contoocook, N.H. The Corps’ New England District Color Guard will open the ceremony at 10 a.m. There will be guided tours of the dams for visitors and other activities.


The Hopkinton Everett Lakes project provides flood protection to residential, commercial, and industrial property downstream on the Contoocook and Piscataquog rivers, which are tributaries of the Merrimack River. The Hopkinton Dam protects the communities of Contoocook, Penacook, Boscawen, Canterbury, Concord, and Bow, while the Everett Dam protects sections of Weare and Goffstown. Operating in conjunction with other Corps dams in the Merrimack River Basin, the project also helps protect major industrial centers along the Merrimack River, including Manchester and Nashua and the Massachusetts communities of Lowell, Lawrence and Haverhill.


Hopkinton Dam is 790-feet-long and 76-feet-high and can impound a 3,700‑acre lake. Nearby Everett Dam is 2,000-feet-long and 115-feet-high and can impound a 2,900-acre lake. The lakes have a combined storage capacity of 51 billion gallons of water and are linked by a canal, which allows water to be diverted between the two pools. 

In November 1927, New England rivers and streams, including the Merrimack River and its tributaries, flooded, claimed several lives and caused serious flood damage. In March 1936, the worst flood in three centuries inundated the eastern and central United States. In New England, floodwaters claimed 24 lives, left 77,000 people homeless, and caused damage in New Hampshire and Massachusetts estimated at $36 million.  As a result of this devastation, New Hampshire and Massachusetts soon initiated a comprehensive plan to reduce the Merrimack River Basin's disastrous flooding potential. In June 1938, Congress approved the construction of the Hopkinton Everett dams as part of a coordinated system of flood control for the basin.


In September 1938, the basin again suffered crippling flood losses when the most powerful hurricane ever to hit the region slammed into the northeast, overflowing riverbanks and causing widespread destruction. It wasn't until 1957 that the state legislatures of New Hampshire and Massachusetts established the Merrimack River Valley Flood Control Commission, which smoothed the way for the project's construction. An interstate compact was approved and the Corps initiated design studies. Construction of the dams began in November 1959 and was completed in December 1962.


Two canals act in conjunction to divert the floodwaters of the Contoocook River stored behind the dam at Hopkinton Lake to the flood storage area behind the dam at Everett Lake. During minor and moderate flooding, there is enough flood storage area behind the dam at Hopkinton Lake to store the floodwaters from the Contoocook River, and there is enough storage area behind the dam at Everett Lake to hold back floodwaters from the Piscataquog River. However, when major flooding occurs, there is not enough land behind the dam at Hopkinton Lake to hold the large volume of floodwaters from the Contoocook River. If not held back, these floodwaters would race downstream and threaten lives and property. There is, however, enough land behind the dam at Everett Lake on the Piscataquog River to hold not only potentially damaging floodwaters from the Piscataquog River, but also the excessive floodwaters from the Contoocook River that the dam at Hopkinton Lake cannot contain.


During the 1987 flood this combined project utilized 95 percent of its storage capacity and prevented $24.5 million in flood damages. Most flooding on the Contoocook River is either minor or moderate and does not require the transfer of excessive floodwaters through the canals.


For up-to-date information, call Park Manager Stephen Dermody at (603) 746-3601 or visit the lakes’ web site at or