Editor’s note: This article is by Nora Doyle-Burr, of the Valley News, in which it was first published March 18, 2016.
WILDER — Some Upper Valley residents are hopeful that the relicensing of three TransCanada dams on the Connecticut River, including one in Wilder, will require changes in the dams’ operation to reduce erosion along the river’s banks.
As part of the Federal Energy Regulatory Commission’s relicensing process, a TransCanada consultant presented an update on three studies of erosion along the river on Thursday at TransCanada’s river control center in Wilder. Discussions of other studies took place later in the day and more are scheduled for today.
TransCanada’s current licenses for the Wilder, Bellows Falls and Vernon dams are set to expire in April 2019, according to the company’s website. FERC issued the current licenses for a 40-year term in 1979. The relicensing process began in 2012 and is expected to take five years.
Consultant John Field, president of Farmington, Maine-based Field Geology Services, said it will be difficult to determine when erosion is caused by the dams’ operations and when it is caused by natural factors.
After outlining the information he has gathered — including aerial photos from 1958 and 1978, more recent maps and photos and a two-year survey of 21 sites along the river — Field said, “Now what do we do with the data? (We’re) trying to understand where it’s occurring; why it’s occurring.”
In future studies, Field said he would try to “tease” apart the causes of erosion.
In addition to the dams’ operations, possible contributors to erosion along the river include tributaries and the sediment they carry, the height of the riverbanks and soil types.
Of the 21 sites Field has been monitoring since 2013, just three are receding from the top of their banks, he said. Several others have shown losses farther down the bank.
But, Field noted, just because erosion hasn’t been apparent at these sites over the past two years, does not mean that they are not eroding. Instead, it may mean that it takes more than two years for a stable bank to become destabilized, he said.
During a break in Thursday’s meeting, Lyme resident John Mudge, who has owned property along the river since 1962, said he has no doubt the dam is the cause of the erosion on his land. He has previously said he has lost several acres to erosion over the years.
Having watched the river level rise and sink over the course of more than 50 years, Mudge said, the fluctuations are contributing to “one of the largest environmental problems facing the Upper Valley today.”
As soil from his property — and others — falls into the river, the sediment is deposited elsewhere, affecting the river’s flow and wildlife habitat. The soil loss is also gradually reducing the valley’s inventory of agricultural land, he said.
“Give it long enough, there won’t be any farmland along the river,” he said.
The recent closing of River Road in Lyme has drawn the community’s attention to the problems caused by erosion along the river.
The Selectboard chose to close a 500-foot portion of the road south of the East Thetford Bridge last fall on the advice of three engineers and the town’s attorney.
At Town Meeting earlier this month, voters approved taking $145,000 from the unreserved fund balance and raising $100,000 in taxes for relocating or reopening the portion of the road that now is closed.
Lyme residents are not alone in their erosion worries.
John Bruno, of Charlestown, also attended Thursday’s meeting and said his primary concern in the dams’ relicensing is erosion. Charlestown is less than 10 miles north of TransCanada’s Bellows Falls dam.
“I think there certainly is a component of the erosion that is related to the fluctuation in water levels,” said Bruno, who lives along the river and sits on the Mt. Ascutney subcommittee of the Connecticut River Joint Commissions.
Bruno said the river is undermining a large tree on his property. Though the bank hasn’t yet collapsed, Bruno said, “it’s a matter of time.”
He did not think it would be feasible for him to reinforce the bank on his own due to a prohibitive cost of tens of thousands of dollars and a complex permitting process, he said.
There are natural reasons for riverbank erosion that can be difficult to separate from the water level fluctuations from the dams’ operations, said Andrea Donlon of the Connecticut River Watershed Council. Though repeatedly wetting and drying the banks as dams do is known to cause erosion, rivers also naturally change their shape over time.
“It’s really difficult to suss out the causes,” she said.
Unlike other scientific studies, in the case of the dams’ effects on the river there is no control group, she said. There is no way to know what the river would be without the dams.
FERC will be accepting comments from April 1 through May 2 on the first erosion study and other studies filed on March 1. The studies can be found on TransCanada’s website at bit.ly/TransCanadaDams.
More studies are expected in May and August, including the final two erosion studies.
