By Bob Audette, Brattleboro Reformer Feb 1, 2021
CHESTERFIELD, N.H. — Last summer was an especially dry summer around the region, leaving many boat owners on Lake Spofford high and, if not dry, kind of muddy.
“Anybody in the channel area and many folks around the lake suffered from the low water level,” said John Zannotti, who asked the Board of Selectmen on Wednesday to reconsider how it adjusts the lake level at Spofford each year. “Some people couldn’t even get their boats into their boathouses.”
Zannotti said that in August he had to move his boat out of the channel because it was impossible to get it from the dock to the main lake without churning up the bottom.
“We had a situation,” he said, asking the board to consider a way of striking a balance between protecting the lake and preserving its recreational use.
The level of Spofford Lake is adjusted by installing or taking out boards at a dam that feeds into Partridge Brook.
Zannotti, who reviewed almost 10 years of board minutes, said the board and the New Hampshire Department of Environmental Services reached an agreement in 2002 to keep the lake level 14 inches below the abutment of the dam, or an elevation of 716 feet and 10 inches.
But, noted Zannotti, the starting point of the lake level in 2020 was set by the Board of Selectmen at 17.5 inches below the abutment, which means because of the summer drought, Spofford Lake never reached the level agreed upon in 2002.
Between Aug. 18 and Sept. 16, said Zannotti, the lake dropped two-and-a-half inches, to nine inches below the agreed upon level.
The low level led to a skegging, or dragging the rear of the boat or the propeller in the lake bottom, especially along the channel, the area of the lake leading up to the dam, and other areas where the lake is shallow even when full.
Zannotti noted that board minutes for mid-2020 state the board height was set at 17.5 inches below the abutment with no discussion noted. Zannotti said this was not unusual in other minutes he reviewed.
“What I haven’t seen for the last 10 years is any kind of discussion at the board,” he said. “Since we’re talking about the jewel of the town there should be some discussion, some process which evaluates the ecological issues and balance against the recreational desires of so many people in town.”
Zannotti said that in a normal year, Spofford Lake can expect between three and four inches of rain through June, July and August.
“We didn’t get any rain,” he said. But, he added, if it had been a normal rain year, the lake level would still have been two inches low.
“The starting point of 17.5 inches was clearly a major contributor,” said Zannotti.
By the end of the summer, it was difficult to launch boats from docks, boathouses and the lake’s launching ramps, where boaters often had to motor onto their trailers, which can cause damage to both the boat and the lake bottom.
“I can’t imagine that that is good for the lake,” said Zannotti.
Mike Gold, who lives next door to Wares Grove Beach, said swimmers at the beach didn’t have much water to swim in as the summer progressed.
“Bathers went well past the markers to get deep enough water to enjoy, thus putting themselves in the heart of the boat traffic lane,” he said, saying water was barely waist deep at the markers.
“It never seemed a day went by when a boat did not run aground while coming in to Wares Grove,” he added.
Liz Pelkey, who lives on the north shore with her husband, Kevin, said they had to use the last tie-down on their 40-foot dock because otherwise, “We were in the muck.”
In their family’s 70 years on the lake, said Pelkey, the lake has never been this low.
She said it’s not just a problem on the shoreline, but also out in the lake, where safely submerged rocks at locations such as Harris Point, Turtleback and Whaleback are getting closer to the bottoms of boats. After hitting a rock at Whaleback, she said, she contacted N.H. Marine Patrol, which sent a pair of officers who eventually moved the markers to note the increased danger.
Pelkey said officers with the N.H. Marine Patrol mentioned they had not seen this particular problem before and that the lake “was definitely a hazard” for people who weren’t familiar with it.
LAKE SEDIMENT Gary Winn, who was leading the meeting with Chairwoman Jeanny Aldrich out, noted he was not on the board when the decision was made about the lake level. However, he said the board received a study of the lake sediment last year that was commissioned by the Spofford Lake Association and conducted by the Dr. Lisa Doner, masters student William Tifft, and Plymouth State University’s Sedimentology Lab. Wynn said the board considered the report when it made its decision last year about lowering the lake level.
The team collected four sediment cores from Spofford Lake, ranging between 25 and 53 feet long, dating back about 300 years.
The report notes that in the last 40 years, the sediment has changed from mostly sand to sand and organic material washed away from the shore of the lake by increased water levels. Turbulence and waves created by boats and small personal watercraft also contribute to shoreline erosion, states the report.
The increase in runoff from the basin that surrounds the lake and the type of materials being washed into the lake at the shore have contributed to low oxygen levels in the lake, states the report.
And last summer, Spofford Lake experienced a cyanobacteria bloom, linked to a type of black algae that grows at the bottom of lakes. Certain conditions can cause the algae to detach from the bottom and float to the surface.
“[T]here has been a distinct and prolonged trend towards more organic material in the accumulating sediments after A.D. 1910, and after A.D. 1980 the amount of organic material reaching the lake bottom exceeds that of any prior time period,” states the report. “[T]he increase in organic deposition is associated with increases in anoxia and reducing conditions in the deep basin ...”
While Spofford Lake is mostly spring fed, it does receive some input from a small number of the brooks and streams. But those are not the sources of most of the material coming into the lake. Now it is coming from the entire basin surrounding the lake, and that sediment is rich in nutrients, notes the report.
“These ancient soils are normally buried and protected from erosion,” states the report.
Due to development around the lake, the sediment gets washed down from the hills and settles on the banks of the lake, eventually getting washed in by waves, contributing to de-oxygenation.
“Along the lake shore ... deep soil layers are continuously exposed and eroded by waves and can supply material to the lake along the entire length of shoreline,” states the report.
Many New Hampshire lakes have developed “armored” shorelines, beaten by wind-driven waves, leaving behind bedrock ledges or a surface layer of boulders and cobbles, states the report.
“Human activities, however, have altered the natural distribution of wave energy along lakes all over the world,” states the report.
A 2013 report issued by the New Hampshire Department of Transportation notes that the natural low water level of the lake is at 711.6 feet elevation, more than five feet below the high-water level set in 2002.
“[L]ake levels have been artificially high by damming for over 100 years,” states the sediment report.
With a high water level, the entire perimeter of the lake is susceptible to erosion of nutrient rich soils.
In addition to the natural waves battering the shore during high lake level conditions, following 1980 there was a boom in the use of low-cost watercraft, in particular, small personal watercraft like Jet Skis.
“Sustained wind speeds of 20 mph can create wave heights on a lake three feet, about the size of a motorboat boat wake travelling at full speed,” states the report. “But wind waves only impact the armored, downwind shores of the lake while boat wakes can impact every shore, most of which are highly vulnerable to wave action. Personal watercraft, in particular, can travel in shallow water at relatively high speeds, causing wakes that travel up onto the fragile shores, directly hitting soils, and exposing roots of tree and shoreline shrubs.”
Bayard Tracy, the chairman of the Spofford Lake Association, said the summer of 2020 was one of the three driest since 1960.
“The lake is a bowl,” he said. “If it rains, we can’t get the water out of the lake fast enough. That’s why we want to run this a little lean.”
High water can cause even more damage to the fragile shoreline, he said.
“Erosion is a big problem,” said Tracy. “It has changed the character of the lake over the past 40 years.”
Tracy told the Reformer before the meeting that when the board set the lake level in 2020, it was acknowledging the challenges outlined in the core sediment report.
“When they put this in, they didn’t know what the weather would be,” said Tracy. “It made a lot of sense.”
Tracy said people are “loving the lake to death,” with 6,800 boat launches last year, an increase of 22 percent over the previous year.
“We did have a pandemic,” he said. “It’s understandable people want to get out on the lake. But still, there comes a point with a lake this size, it gets stressed and starts to change.”
He also noted that boats skegging could also be a result of too much sediment being washed into the lake, filling it in slowly.
“And when you lose 10 inches of water level, which is what happened last summer, it makes a huge difference,” said Tracy.
The town is developing a steep slopes overlay, which is aimed at protecting the lake by imposing stringent regulations on development on the hills above it.
“This steep slopes thing should have been done 20 years ago,” Pam Walton, a former chairwoman of the SLA, told the Reformer before the meeting. “Without that, this lake is going to continue to have problems.”
At the close of his presentation, Zannotti suggested the board take more seriously the lake level and not adjust the dam without discussion.
“The board should be proactive in managing the lake level throughout the summer,” he said.
He also asked the board to consider producing a boater safety pamphlet that explains what the town expects from users of the lake, including the 150-foot no wake zone, which is designed to protect swimmers and people in canoes and kayaks, as well as the shoreline from erosion.
“Education is probably a good first step,” he said.
Wynn said the board will be looking at the issue “on a more formal basis “ in the future.