Surry Mountain Dam is a part of a network of flood control dams on tributaries of the Connecticut River. Built in 1941, Surry Mountain Dam is the oldest U.S. Army Corps of Engineers flood control dam in the Upper Connecticut River Basin, and one of the oldest in New England. The dam is located in Surry, New Hampshire on the Ashuelot River, 34.6 miles north of where the Ashuelot River and the Connecticut River converge. Surry Mountain Dam not only prevents flooding along the Connecticut River, but works in conjunction with Otter Brook Dam to prevent local flooding in Keene and other downstream communities along the Ashuelot River. The lake has a storage capacity of 10.6 billion gallons of water, drains an area of 100 square miles and has a maximum pool level of 65 feet (normal pool level is 15 feet.)

The Reservoir Regulation Team (RRT), located in Concord, MA is the "nerve center" for the New England flood control dams such as Surry Mountain Lake. Using radio and satellite communications, RRT constantly monitors river levels and weather conditions that influence flood control decisions. By monitoring these conditions, RRT can coordinate the efforts of all the flood control facilities in New England

Park rangers, in conjunction with RRT, regulate the amount of water released downstream by raising or lowering two 4.5'x10' gates located in the granite gatehouse at the dam. In a time of high water, the gates are lowered in order to hold back the water, only to be released when downstream river conditions begin to recede.

In April 1987, two storms dropped over 4 inches of rain, and significant run-off occurred from snow melt, causing the first and only emergency spillway discharge to occur since the dam was built. Significant flooding did result in the Keene area, when the outflow rose to 2,250 cfs which greatly exceeded the channel capacity of 1,250 cfs. Although some flooding did result, it was estimated that Surry Mountain Dam prevented $7,956,000 in damages along the Ashuelot and Connecticut Rivers from that two storm event.

Interesting Facts - Surry Mountain Dam

• Constructed 1939 - 1941

• Cost of construction - $2,551,000

• Lenght of Dam - 1,800 feet

• Height of Dam - 86 feet

• Top width of dam - 30 feet

• Total embankment - 1,105,000 cubic yards

• Elevation, top of dam - 568 msl

• Length of spillway - 338 feet

• Elevation, spillway crest - 550 msl

• Drainage area - 100 square miles

• Inches of runoff - 5.9"

• Maximum capacity - 31,680 acre-feet (10.6 billion gallons)

• Highest pool of record - April 1987, pool = 66.1 feet (+100% full)

• 2nd highest pool of record - October 2005 = 63.47 feet (96% full)

Last Updated: January 24, 2011