BOSTON — The latest flooding in Vermont has heightened concerns about the state’s hundreds of dams, a third of which are more than a century old.
This week’s deluge from Hurricane Beryl’s remnants was a minor blow to the hundreds of dams compared to last year’s flooding, when five failed and nearly 60 overflowed. But the second major 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 aging dams still standing on our rivers provide no flood protection, despite popular belief,” said Andrew Fisk, Northeast regional director for the environmental advocacy group American Rivers. “Dams that were not specifically designed for flood protection frequently fill to capacity and provide no storage capacity. And they often divert water at high velocities outside the main channel, leading to bank erosion and impacting communities.”
The challenge for dams in Vermont is taking place all over the country as more dams overflow or fail during heavy rains. The Rapidan Dam, a 1910 hydroelectric dam in Minnesota, was badly damaged last month by the second-worst flooding in its history. And in Texas, flooding damaged the spillway of the Lake Livingston Dam, about 65 miles (105 kilometers) northeast of Houston.
There are about 90,000 major dams in the U.S. At least 4,000 are in poor or unsatisfactory condition and could kill people or just harm the environment if they failed, according to data from the U.S. Army Corps of Engineers. They inspections, upgrades and even emergency repairs.
Like the rest of New England, Vermont has mostly older, small dams built to power textile mills, store water, or provide irrigation to farms. The concern is that they have outlived their usefulness and Climate change can cause storms They were never built to withstand this.
Last year’s flooding in Vermont drew an inordinate amount of attention to dams, largely because of the failures and near-failures. In the capital city of Montpelier, a dam threatened to send water over its emergency overflow and through parts of the city. The National Inventor of Dams, a database maintained by the U.S. Army Corps of Engineers, lists 372 dams in the state, 62 of which are rated as highly hazardous, meaning lives could be lost if the dam fails. Ten of those were rated as in poor condition, meaning remedial action is needed.
State officials say they actually regulate 417 dams, but there are hundreds of others that are too small and pose little danger to be regulated.
Last year’s storms prompted a rapid inspection of all dams in the state, with more than $1.5 million spent on stabilizing and repairing storm damage.
“The team had never been confronted with a situation where, you know, 8 inches of widespread rainfall across the entire state of Vermont,” said Neil Kamman, director of the Water Investment Division at the Vermont Department of Environmental Conservation. “It put a strain on all the facilities 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 of and created a lot of unknown uncertainties on the landscape in terms of downstream risk because of, you know, potential dams that were destabilized.”
In response, the Legislature approved the appointment of four more staff members to the dam safety program, bringing the total to nine, and appropriated an additional $4 million for a dam safety program, up from $200,000. That money can be used for emergency hazard reduction, dam restoration or removal.
This time, dam safety officials said the damage was minimal. No dams are believed to have failed and only one dam — Harvey’s Lake in Barnet, which is classified as a low-risk structure — overflowed. But even then, there is unlikely to be any significant impact on property or nearby roads, officials said.
Julie Moore, secretary of the Vermont Agency of Natural Resources, said at a news conference Friday that inspections have shown that the Winooski River Valley Flood Control Reservoir “continues to do its job well” and that levels at the Waterbury Reservoir “are stabilizing with ample storage capacity remaining.” She also said officials had completed inspections of “seven high-risk” dams in the northern part of the state and that “no damage has been identified.”
This year’s floods came too early for the extra money and staff to have an impact, but Kamman said the experience of responding to last year’s flood helped shape the team’s more robust response this time around.
“The biggest difference between the response this year and last year is the fact that we had a plan in place for a large-scale event that would put a lot of pressure on a lot of facilities at once,” he said.