CANAAN — During the recent warm, humid weather, any swimmer or boater headed for relief at Goose Pond would have been out of luck.

Since the New Hampshire Department of Environmental Service’s Dam Bureau began drawing down the water in Goose Pond in Canaan last fall in order to make repairs to the pond’s dam, the water level has dropped approximately 20 feet, said Corey Clark, the bureau’s chief engineer.

As Goose Pond, approximately 3-to-4 miles long and a half-mile across, has shrunk from 620 acres to roughly 200 acres of remaining water, the drawdown has exposed a ghostly landscape of boulders, rocky outcrops, small islands and the stumps of trees that were cut in 1918 to make way for the first dam.

On a torrid morning last month, Clark was on site to check on the progress of two out-of-state crews working to make repairs and mix the cement that will line the tunnel leading from the dam.

Of the 273 state-owned dams, Clark said, the bureau is responsible for maintenance and repairs on 208 dams; of those, 64 dams, including the one at Goose Pond, are considered high-hazard.

The last time a complete drawdown occurred in order to make repairs was in 1990, Clark said. Starting in 2012, leakage has been found, he said.

If the dam were to fail, flood waters would cross Route 4 into Enfield, hit Mascoma Lake, run into the Mascoma River and, projections show, would reach Lebanon with a “probable loss of life down stream,” Clark said.

Michael Riese, a full-time resident on Goose Pond who is also the president of the Goose Pond Lake Association, kayaked the lake with his wife in April, but that is no longer possible given the shallowness of the water. There are 180 houses on the lake, and of those, Riese said, between 35 and 40 are owned by year-round residents. The Lake Association helps to monitor both water quality and the wildlife population, and works to keep out invasive plant species, Riese said.

Although homeowners and renters are not thrilled about seeing Goose Pond empty during the summer months, when recreation is arguably at its best, “nobody from the Lake Association is chaining themselves to the dam,” Riese said.

The state gave homeowners plenty of notice, said Kevin McCullough, who has had a house on Goose Pond since 2010. While it would be nice to have the lake available this summer, the options came down, he said, to either “a planned drawdown or a catastrophic drawdown.”

Given the potential threat to life, there was no opposition to emptying the dam so that repairs could be made, Riese said, adding that the Dam Bureau “has been transparent, terrific and open” in its communications with residents.

Currently, Goose Pond is the Dam Bureau’s biggest project, Clark said.

On average, the bureau draws down two to three bodies of water annually, while simultaneously tackling other projects. Dams are “very, very expensive structures, so we have to prioritize and work with the (state) Legislature and do what we can to maintain the dams in a satisfactory condition,” Clark said.

The dam’s cost is roughly $6.4 million. The majority of the cost is covered by the federal 2021 American Rescue Plan Act; $500,000 is covered by the state of New Hampshire, Clark said. Work is expected to continue through mid-winter 2025 and conclude by the spring.

“The intent is to start filling the pond this winter,” Clark said. Depending on the meteorological conditions and spring runoff, it should take about a year for Goose Pond to fill up, he added.

Apart from repairs, the crews will install 20 pressure-relief wells, 4 inches across, along the base of the dam to capture water and bring it down to Goose Pond Brook, Clark said.

The slope of the embankment leading up to the dam will be flattened to improve stability and permit the installation of drainage material to capture any potential seepage; and for aesthetic reasons.

There are presently five gates in all at the dam: when the project is completed, that number will be reduced to three gates, both new and rehabilitated, that will allow easier management of the pond’s water levels.

The Bureau’s criterion is that a high-hazard dam must withstand the effects of a 1,000-year storm event; this requirement recently replaced the criterion that high-hazard dams must withstand a 100-year storm event multiplied by 2.5, Clark said. The bureau also requires that one foot must separate the top of the dam from the surface of the body of water.

“The analysis that goes into determining these design events rely on current rainfall amounts. These rainfall amounts are updated as necessary based on current climate conditions,” Clark wrote in an email.

As the pond has drained, Clark said, “it appears that most of the wildlife has migrated down (stream) with the lowering of the water surface.”

Residents have found in the exposed bottom beer cans, boots, fishing tackle — and even one 14-foot wooden row boat, Riese said.

Now the narrow, shallow tributary that originates at Goose Pond’s northern headwater and runs to the lake’s southern end, where the dam is located, is a reminder of where a stream once ran through woodlands.

Nicola Smith can be reached at mail@nicolasmith.org.