Harvey's Lake Dam
DAM UPDATE | Steve Adler
More progress was made during calendar year 2015 on improving the outflow from Lake Harvey than had occurred in the preceding 40 years. Members of the Lake Harvey Association will recall that at the last annual meeting, your Trustees reported on the plans to reopen the Dam to its original capacity. In addition to its historical function of providing power to downstream mills, the Dam on the outflow creek from Lake Harvey has functioned to maintain consistent water levels in the lake. It was supposed to allow excess water to be released over the spillway and through openings in the Dam during high water events. These latter functions became far more difficult to achieve as the creek silted in and the Dam became overgrown with vegetation, reducing its capacity to allow release of flood waters.
As a consequence, flood waters have for decades been backing up into the lake, bringing with them nutrient rich water from South Peacham which has increased lake vegetation and created a delta at the entrance to the outflow creek. Over time, this adversely affects water quality in the lake, recreation potential and fish habitat.
We last reported to the Lake Harvey Association members that the Barnet Selectboard had embarked on Phase I of a three part project to address the situation. We now happily report that Phase I was completed very successfully and as shown on the photographs accompanying this update, the entire width of the Dam has been reopened and the silt immediately upstream of the Dam dredged out. This has essentially quadrupled the spillway capacity at a cost of $134,798 to the Town of Barnet (approximately $15,800 to the project manager Fairbanks Mill and $119,000 to contractor JA McDonald). With greater release capacity, the water flowing through the fertilizer-rich farmlands in South Peacham will generally take the path of least resistance and flow over the Dam and not back up into the lake. The exception will be in storm events where the outflow overwhelms what the Dam can handle and water continues to back up into the lake. We know from our engineering studies and the calculations of Dr. Richard Downer that there are events where the existing Dam, even operating at maximum capacity, can only handle about 25% of the total outflow because of the very large watershed area for South Peacham Brook. That is the problem we still need to address.
Phase 11 of this project involves installing a new Dam, likely with an adjustable system such as a rubber bladder, which will allow greater control of Lake Harvey water levels and be high enough so that flood waters flowing from South Peacham Brook do not back up into the lake. Enter the beavers. The beavers were kind enough to construct a remarkably efficient dam in the narrows of the outflow creek. This dam worked so well that even when all the flashboards were removed from the existing Dam, the lake level remained high. Thus, we did not have the projected three foot drop in lake levels that required all of us to remove boats from the lake by Labor Day 2015. The beavers’ fine engineering also identified a way to construct a dam on the outflow creek which protects the Loon habitat and reduces the cost of Phase II by use of a significantly shorter dam than had been anticipated. The result of all of this: we now have our existing Dam operating at its peak efficiency and we know pretty closely where to locate a new dam.
The Town of Barnet is now actively preparing for Phases II and III of the Lake Harvey Dam Project. This will involve, for Phase II, doing some soil borings to more specifically identify the size and design of a new dam located about two/thirds of the way down the outlet creek and shortly before the confluence of the South Peacham Brook, and then permitting and contracting for building a new dam. Phase III would involve removing the existing Dam or at least lowering it substantially. These alterations will be expensive and require significant State permitting. At the March 2016 Barnet Town Meeting, the plans were explained to the Town by Selectboard member Dylan Ford who has become the point person for these projects and an excellent proponent. Judging by comments at the Town Meeting, most Barnet residents understand and agree with the Selectboard’s efforts to improve water quality and preserve fish habitat in this vital municipal resource which is Lake Harvey. Trustee David Price has volunteered his time to work with Ms. Ford in effort to try and secure grant money for this project. It is hoped the project will itself occur in 2017 with soil borings at the proposed new dam site over the winter of 2016-2017. It is always possible that the Town will look to the Lake Association for support. Thus it remains vital that this Association speak with a unified voice. We need to have as many camp owners and visitors to the lake as possible joining our Association and continuing to support our efforts to solve this decades old problem of the Dam on Lake Harvey.
|THEN: Dam 1972||NOW: Dam May 11, 2015|
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