Otter Brook Dam in Keene, New Hampshire,
is part of a
network of flood control dams on tributaries of the Connecticut River. Otter Brook Dam not only
prevents flooding along the mainstem of the Connecticut River, but it
also works in conjunction with Surry Mountain Dam in Surry, New Hampshire, to protect the city
of Keene, and downstream areas along the Ashuelot River.
Completed in 1958 at a cost of $4.4 million, Otter Brook Dam has a storage capacity of about 6 billion gallons of water.
Park Rangers, in conjunction with RRT, regulate the amount of water released downstream by raising or lowering the three 2.5'X 4.5' gates located in the gatehouse at the dam. In a time of high water, the gates are lowered in order to hold back the water, when downstream river conditions begin to recede, the gates are raised to release the stored water.
Between late March and early April of 1987, two storms dropped over 5.5 inches of rain, causing the first and only spillway discharge at Otter Brook Dam. Fortunately, Otter Brook Dam had stored water long enough for the flood water from uncontrolled areas in the watershed to recede by the time the spillway discharge occurred on April 7, 1987. Although the 750 cfs peak outflow exceeded the 650 cfs channel capacity it did not cause additional downstream damage. It was estimated that Otter Brook Dam alone prevented $3,593,000 in damages from that two storm event.
Interesting Facts - Otter Brook Dam
- Constructed 1956 - 1958
- Cost of construction - $4,132,500
- Lenght of Dam - 1,288 feet
- Height of Dam - 133 feet
- Base width of dam - 700 feet
- Top width of dam - 25 feet
- Total embankment - 1, 010,000 cubic yards
- Elevation, top of dam - 802 msl
- Length of spillway - 145 feet
- Elevation, spillway crest - 781 msl
- Area of reservoir - 458 acres
- Drainage area - 47.0 square miles
- Maximum capacity - 17,600 acre-feet (5,960,000,000 gallons)
- Highest pool of record - April 1987, pool = 99.4 feet