A former sawmill dam on the Bogue Branch in Bakersfield is being removed, a project that would reconnect 22 miles of stream and, engineers hope, reestablish brook trout passage through the site.
Work should be completed this week, said Lauren Weston, manager of the Franklin County Natural Resources Conservation District, which is in charge of the project.
The Bogue Branch is a tributary of the Missisquoi River’s Tyler Branch, which drains almost 60 square miles of Bakersfield, Enosburg and several other Franklin County towns.
Ultimately, the Missisquoi River flows into northern Lake Champlain.
“If we’re able to remove it in a designed way,” Weston said of the dam, “it’s better for the long-term health of the river.”
Engineers started planning to remove the roughly 125-foot-wide dam several years ago, concerned that sediment building up behind it could cause the structure to fail.
Then, during the 2019 Halloween storm that caused flooding across the state, that’s exactly what happened, Weston said. Bakersfield received more than 6 inches of rain, causing part of the dam to rupture and sending large amounts of sediment downstream.
If the rest of the dam were to collapse, she said, even more sediment would suddenly gush downstream, which could damage a nearby culvert.
By removing the entire structure, engineers hope sediment will move downstream more naturally, establishing what’s known as a geomorphic equilibrium. That would also allow brook trout to live near where the dam’s now located and pass through the area in either direction.
Brook trout can help indicate the health of water they inhabit, according to the U.S. Fish and Wildlife Service. Large numbers of the fish point to a healthy environment, while a decline indicates a deteriorating habitat and poor water quality.
“Certain fish really like to nest in small gravels and cobbles,” said Matt Schley, a water resources engineer at Stone Environmental who is working on the dam removal. “So you really want a balance of natural streambed material.”
The dam, known as Johnsons Mill, was built in 1928. It is located off Witchcat Road, about five minutes south of the Cold Hollow Sculpture Park.
State officials pointed out as early as the 1950s that the dam had minor problems from surface deterioration and insufficient maintenance, according to a University of Vermont study, and by the 1970s, state inspectors had noted cracks in the concrete.
The dam’s spillway may also have been damaged by a heavy snowmelt in 1996, according to the study. In 2016, state officials recommended that the dam be considered for removal.
Weston said dam removal projects have accelerated across Vermont since Tropical Storm Irene swept through much of the state almost exactly a decade ago.
The infrastructure damage caused by the storm made people reconsider how local waterways are managed, she said, and which solutions may work better than others.
“Dams fail,” Weston said. “They’re not permanent structures.”
