Flooding in Vermont raises concerns about the future of the state’s hundreds of aging dams

BOSTON– The latest flooding in Vermont has added new urgency to concerns about the state’s hundreds of dams, a third of which are more than a century old.

This week’s deluge caused by the remnants of Hurricane Beryl wasn’t as bad for the hundreds of dams compared to last year’s floods, when five failed and nearly 60 overflowed. But the second serious flood in a year raises concerns about the viability of these structures, as climate change brings heavier rains and more powerful storms.

“The many thousands of outdated dams that remain on our rivers do not provide flood protection, despite what many may think,” said Andrew Fisk, Northeast regional director for the environmental advocacy group American Rivers. “Dams not created specifically for flood protection are regularly full and do not provide storage capacity. And they also often direct water away from the main channel at high speeds, which causes bank erosion and impacts on communities.”

The challenge facing dams in Vermont is playing across the country as more dams overflow or fail during heavy rains. The Rapidan Dam, a 1910 hydroelectric dam in Minnesota, was seriously damaged last month by the second worst flood in its history. And in Texas, flooding damaged the spillway of the Lake Livingston dam, about 65 miles northeast of Houston.

There are about 90,000 significant dams in the US. At least 4,000 are in poor or unsatisfactory condition and could kill people or just harm the environment if they fail, according to data from the U.S. Army Corps of Engineers. They they need inspections, updates and even emergency repairs.

Like the rest of New England, Vermont has mostly small, old dams built to power textile factories, store water, or provide irrigation for farms. The concern is that they have outlived their usefulness and climate change can bring storms they were never built to withstand.

Last year’s flooding in Vermont brought outsized attention to dams, largely due to their failures and near-failures. In the capital Montpelier, a dam was at risk of sending water down the emergency spillway and through parts of the city. The National Dam Inventor, a database regulated by the U.S. Army Corps of Engineers, lists 372 dams in the state, with 62 classified as high hazard, meaning lives could be lost if the dam fails. Ten of them were classified in poor condition, meaning corrective measures are needed.

State officials say they actually regulate 417 dams and that there are hundreds of others that are too small and of minimal risk to be regulated.

Last year’s storms led to a rapid inspection of all of the state’s dams, with more than $1.5 million spent to stabilize and repair storm damage.

“The team has never come across a situation of, you know, 8 inches of widespread rain across essentially the entire state of Vermont,” said Neil Kamman, director of the Water Investment Division at the Vermont Department of Environmental Conservation. “It stressed every facility that the state of Vermont owns and that the dam safety team manages, but it filled hundreds of dams, caused the failures that you know about, and created a lot of unknown uncertainties on the landscape in terms of downstream risk due to , you know, to the destabilization of possible dams.”

In response, the legislature approved the hiring of four employees for the dam safety program, bringing the total to nine, and allocated an additional $4 million for a dam safety program, up from $200,000. This money can be used for emergency risk reduction, restoration or removal of dams.

This time, dam safety officials said damage was minimal. No dams are believed to have failed and only one dam – Harvey’s Lake in Barnet, which is classed as a low risk structure – has overtopped. But even in that case, there was not likely to be any significant impact on nearby properties or roads, officials said.

Julie Moore, secretary of the Vermont Agency of Natural Resources, said during a news conference Friday that inspections found that the Winooski River Valley flood control reservoir “continues to do its job well” and that levels in the reservoir Waterbury “is stabilizing with plenty of storage remaining.” These dams and the East Barre Dam are essential for flood control in an area stretching from Barre to Essex.

She also said authorities have completed inspections of “seven particularly at-risk dams” in the northern part of the state and that “no damage has been identified.”

This year’s floods occurred too soon for the additional money and staff to make an impact. But Kamman said last year’s flood response experience helped shape the team’s more robust response this time around.

“The biggest difference between this year’s response and last year’s is the fact that we came up with a game plan for a widespread event that would overwhelm a large number of facilities at the same time,” he said.