Vermont’s largest dam is in need of an upgrade.
Or at least that’s what the Vermont Department of Environmental Conservation and the U.S. Army Corps of Engineers have proposed in a plan to update the Waterbury Dam and restore its full flood protection capacities.
“The state operates the major flood control facilities in the Winooski River Valley that are designed to protect our population centers from Barre all the way down to Richmond from catastrophic flooding,” said Neil Kamman, the director of the department’s Water Investment Division. “Waterbury is our biggest and most complex of those. It’s absolutely critical to maintain public safety for Vermonters that live nearby.”
The gates that hold water in the Waterbury Reservoir are deteriorating and can only hold three-quarters of the water levels the dam was originally intended to retain to protect against flooding, according to Ben Green, the dam safety engineer with the department. While the floodgates are still able to protect downstream communities from high water levels in the Winooski River, the project aims to address risks that engineers identified as early as 2005, the public notice states.
The declines come, in part, from a chemical reaction that causes concrete to swell and crack, but most of the need for repair comes from age — the dam is nearly 100 years old, Green said.
To protect the most damaged sections of the spillway from further cracking, engineers propose repairing the most-damaged concrete throughout the dam’s spillway — a process that involves chipping back the exposed concrete and sealing it to protect against future instances of this chemical reaction.
The proposal also suggests fully replacing two flood gates from the original dam that was completed in 1938 and refurbishing the dam’s third gate, which was built in 1950. The plan recommends replacing a pedestrian bridge with a stronger one at a higher elevation. That would allow it to support maintenance vehicles and equipment for occasional upkeep of the dam and protect it from high water levels.
The only new design the plan puts forth is a concrete apron — a ramp beneath the dam to hold bedrock in place and protect against erosion as water comes over the dam, Green said. Geological analyses have found the area beneath the dam’s spillway is susceptible to future erosion without added structure, he said.
The state originally began construction on the dam in 1933 — six years after the Winooski River saw historic flooding — to hold water upstream in the Waterbury reservoir and protect against downstream flooding. These spillways’ capacities were pushed to extremes during the historic flooding the state saw in 2023.
“Really the most positive part of this project is that the completion of it will allow full restoration of the flood pools, so we’ll improve the dams’ future capability to safely store and manage flood pools,” Green said.
Yet those benefits are still far off since financing for the project has not been fully secured, and the engineering design and permitting have not been completed. The project team has completed the preliminary engineering analyses and environmental assessment. Community members are able to offer public comment online until Feb. 25.
Vermont’s congressional delegation has secured authorizations for funding of the project through the federal Water Resources Development Act. The funding split had been 35% state and 65% federal, up until the 2022 legislation, Kamman said, which brought the split to 7.5% state and 92.5% federal.
The U.S. The Army Corps of Engineers has close to $50 million in the bank for this project but still needs another $40 million, Kamman said. Since the existing funds are dollars appropriated for the U.S. Army Corps of Engineers, and not a federal grant, he sees more stability in a time when federally funded projects are largely in limbo.
Construction is slated to begin in 2027 and is expected to take three years. Even as officials look to close this funding gap, the state is moving ahead on the project.
“It is obviously a very uncertain environment with respect to federal appropriations right now,” Kamman said. “But water infrastructure is pretty important stuff, and we will see how things progress in the coming congressional sessions.”
Clarification: This story has been updated to make it clear when the state originally began construction on the dam and when that work was completed.
