Dam Repairs Moving Forward Slowly

Concord — April 29, 2009 — DES Dam Bureau official Steve Doyon says he is “cautiously optimistic” that the plan to repair the Ossipee River dam complex this year will continue to move forward despite the State’s economic woes. Speaking with the Alliance by email, Doyon said funding for the project, which was authorized in 2006, remains in place and the department expects to present the final plan to the Governor and the Executive Council before the end of the year.

If the plan is approved, the state will replace the deteriorating concrete dam at the northern outlet channel, which is known as the Berry Bay Dam, by enlarging the spillways and installing an automated hydraulic gate system so that discharge capacity can be increased remotely during times of potential flooding.

Depending upon the final price tag and the availability of construction funds, the project to improve the northern outlet may occur in two phases. The first would be the replacement and enlargement of the existing concrete dam, and the second would be the installation of the automated gates.

If it does become a two-phase project, DES will use stoplogs, similar to the system that exists now, to control impoundment levels until the automated gates are installed.

The second dam at the complex, which is on the southern outlet channel and is known as the Head Works Dam, does not require work and will remain in place and be operated manually. The Dam Bureau has selected consulting engineering firm GZA GeoEnvironmental, Inc. to negotiate a contract for the work, according to Kent Finemore, the Dam Bureau representative who is coordinating the work.

The consulting firm will conduct a flood hazard analysis, prepare construction estimates and manage the state permitting process. Once the Governor and Executive Council have signed off on the project, engineering work can begin. DES hopes to begin the permitting process within six months of approval by the Governor and Council.

The water level of the lake has been managed since the dam was constructed in 1919, originally for the benefit of downriver commerce and later for recreation. Each fall the level is lowered to minimize ice damage to the shoreline, and each spring it is raised to accommodate boating and swimming.

During the summer, constant attention to predictions and weather conditions result in opening and closing some gates on the south side as often as five times a week. Reaction time with the present manual system may be days rather than minutes.

Dam Bureau officials say improving the dam control system could reduce flooding, but they concede it won’t prevent it because the channels that connect the big lake and bays create a series of natural bottlenecks that impede the flow of water to the Ossipee River, its only egress, which results in flooding.

[This story is from the Alliance’s spring newsletter, which is on its way to you by mail or available online at www.ossipeelake.org. Click the News tab and then the Newsletter link.]

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