Drawdown allows for dam repairs in Canaan
Published: 12-09-2023 12:16 AM
Modified: 12-09-2023 11:41 PM
CANAAN — The New Hampshire Department of Environmental Services began drawing down the water level of Goose Pond by a foot a day starting in October to allow for repairs to its century-old dam.
But having drained the pond to the department’s desired height — around 22 feet below typical level — the bureau’s work isn’t totally finished.
With heavy rain in the forecast for this weekend, the pond will have to come down “a little bit more” as it naturally refills, said Corey Clark, chief engineer for NHDES’ dam bureau.
“We still can’t discharge too, too much,” Clark said, lest they inundate downstream neighbors.
Repairs are set to include the installation of 20 “relief wells” around the base of the dam that will ease pressure from groundwater, a pipe system to discharge water into Goose Pond Brook, and fixes to the dam’s spillway, the concrete chamber that discharges water into Goose Pond Brook.
A trio of wooden floodgates at the bottom of the dam also are set to be replaced with a single, stainless steel gate.
The repairs come about a decade after department officials were first alerted to cracks in the 31-foot-tall dam’s concrete and following required monitoring and feasibility studies.
The project, which will be completed with federal money from the American Rescue Plan Act, is estimated to cost about $6 million, and is part of a larger effort in the state to replace aging dams.
In the winter, NHDES typically drops the water level of the lake by about eight feet to prevent ice damage to the shoreline and create space for springtime runoff. But this fall’s dramatic drawdown is of another order of magnitude.
The lake, which typically covers around 600 acres in Canaan and Hanover, has shrunk to about a quarter of its size.
The drawdown will stay in place until the end of construction, which is expected to begin this spring and last through the winter of 2025.
In the meantime, the state will continue to monitor water levels at Goose Pond, and adjust as necessary.
Frances Mize is a Report for America corps member. She can be reached at email@example.com or 603-727-3242.