[mcdude]

Speaking of dams and lake levels, etc.....interesting article in the Daily Sun today about how the output from the dam affects people downstream.

State drops Silver Lake mean high water mark by 2 feet

BELMONT — After reassessing the natural mean high water mark (NMHWM) of Silver Lake, the New Hampshire Department of Environmental Services (DES) on Friday announced it was 466 feet, two feet below the level applied for the past three decades.
The agency detailed its findings in a report submitted to the Legislature last week. Jim Gallagher, chief of the Dam Bureau at DES, who oversaw the preparation of the report, said that on the strength of the analysis of new evidence the agency will revise its records to indicate that 466 feet is the accurate NMHWM of Silver Lake.
Paul O'Connell of the Silver Lake Association said that he has some questions about the methodology and findings of the report and preferred to reserve judgment until they answered.
The state holds all surface waters in public trust and, for lakes of 10 acres or more, owns not only the water but also the land beneath it. The boundary between private property and the public trust is defined by the NMHWM. The NMHWM refers to a line on shore left by the common and usual rise and fall of water, marked by such physical characteristics such as shelving of the bank and changes in the type of soil and species of vegetation.
The issue first arose in 2004 when town officials informed residents submitting site plans and seeking building permits that according to DES the NMHWM was 468 feet. At 468 feet, some 125 property owners at Silver Lake found that between one foot and 49 feet of their lots belonged to the state, depending on the slope of the shoreline, and some found their homes completely surrounded by water.
O'Connell estimated that the issues affecting many, but not all, shorefront property owners would be resolved by lowering the NMHWM by two feet. "It all depends on the slope of their lot," he said.
The Silver Lake Association petitioned DES to reconsider its decision. Determining the NMHWM of Silver Lake is especially challenging since it has been a managed water body where flows and levels have been regulated since the construction of the Lakeport Dam and Lochmere Dam 160 and 102 years ago respectively. Following an extensive study, in 2008 DES reaffirmed its original determination of 468 feet.
The association appeals and when its appeals were denied, turned to the Legislature. Senator Jim Forsythe (R-Strafford) introduced legislation to establish the natural mean high water mark at 465 feet. At the hearing on the bill, the association presented photographs taken upstream of the Lochmere Dam during the biannual drawdown of Lake Winnisquam that revealed stumps of mature trees in the riverbed, which are covered by water during normal flows. The photographs suggested that natural water levels before the Winnipesauke River was dammed were below 468 feet and prompted DES to undertake a fresh study and report its findings to the Legislature.
In October, during the drawdown, DES conducted a second field study, beginning with plotting the location, measuring the elevation and identifying the species of the stumps. Of the ten stumps, eight — two red oaks and six white pines — remained of trees that typically grow in upland surroundings, not in standing water or saturated soil. The average elevation of the stumps was measured at 476.74 feet, which represented the shoreline of the river in its natural condition before the Lochmere Dam was built.
The next step was to determine the flow rate that would reach the elevation of the stumps or the shoreline of the river. Using a model developed by the U.S. Army Corps of Engineers, the flow rate was calculated at 1,110 cubic feet per second (cfs). With the flow at Lochmere of 1,110 cfs, the corresponding flow rate downstream at the Tilton streamgauge was estimated by multiplying the flow at Lochmere by a factor of 1.108, which represents the ratio of the drainage area of the Winnipesaukee River at Tilton — 417 square miles — to its counterpart at Lochmere — 425 square miles. Therefore, when the river reaches the elevation of the stumps — 476.74 feet — the flow at the Tilton gauge is 1,230 cfs. When the flow rate at Tilton is 1,230 cfs, the water level at Silver Lake would be about 466 feet.
"Relying solely on the evidence provided by the stumps," the report reads, "the NMHWM of Silver Lake would be 466 feet."