LACONIA — Deterioration is quite visible on 70-year-old Avery Dam near City Hall.
Sections of concrete have chipped off and a walkway appears bowed.
But there’s nothing to indicate a safety problem, said Corey Clark, a state Department of Environmental Services engineer who examined the structure Tuesday along with DES dam operator Peter Ames.
“It’s in rough shape but there’s not a ton of rebar showing,” Clark said.
Depending on the type of concrete that was used to build the dam, the surface damage may not pose a larger threat.
“There are a couple of dams in the state that are in pretty rough shape visibly, but structurally they are sound because it is all just massed concrete,” he said.
Ames said Opechee Bay will be drawn down next year, allowing a closer inspection of the base of the dam on the Winnipesaukee River.
“Structurally, it’s sound. It’s not like it’s going to blow out,” Ames said.
Clark was working nearby and came to Avery Dam to investigate public concerns at the request of DES Chief Engineer James Gallagher. Former Planning Board member David Stamps and The Laconia Daily Sun had posed questions about the dam to Gallagher.
Gallagher said the state-owned dam was last inspected in 2016 and found to be in fair condition and not in danger of failing. It is scheduled to be inspected again this year.
“The concrete part of the dam is deteriorating and is going to need some work,” he said. “It is what we call maintenance work.
"The concrete deterioration is not affecting the structural stability, but it is something that needs to be addressed to keep it from deteriorating further," Gallagher said. “It will be put in the next biennial request.”
Gallagher said this is considered a low-hazard dam, meaning if it were to fail, there would be property damage but loss of life would not be expected.
“Opechee Bay would drain, but Winnisquam could easily hold the contents of Opechee,” he said.
Although a private company generates hydroelectric power from the dam, the structure's primary purpose is the recreational benefit of impounding water for the bay.
Stamps said he continues to have concerns. He questioned whether the state will provide money needed to make repairs.
“You know what happens with capital budgets in New Hampshire, you know what happens with them,” he said.
The first stone-filled, timber-crib Avery Dam, built by Daniel Avery, was put in place in 1790 or 1791, said local historian Warren Huse.
A section of the dam has the dates, 1790 and 1949, carved into the concrete along with the words, "Avery Dam," but all the letters in Avery, except the A, have deteriorated away.
Huse said the first dams in this area helped power sawmills and gristmills. Waterpower was also used to run textile mills. Later, hydroelectric power was generated.
“In the late 1880s, electricity for the first electric lights in Laconia was generated from the waterpower of the Avery Dam,” Huse said.
Owner-operators of the hydroelectric plant at Avery Dam have been Algonquin Power, Davis Power of California and, most recently, Dichotomy Capital of Scarsdale, New York, which took ownership in 2016.
Work is in progress on the hydroelectric facility, which is controlled by computer and sustained some damage recently when a gate was placed in an improper position.