Dam walk yields views and warnings

COLEBROOK — A dozen or so people ambled across the concrete and stone behemoth of the Colebrook River Dam under a crisp autumn sky on the morning of Saturday, Oct. 5 while a bald eagle circled overhead, occasionally divebombed by an angry avian neighbor. It was one of the final Housatonic Heritage Walks of the season, and the topic was floods.

“As a Corps, we’ve gotten away from saying flood prevention because it’s just not realistic to prevent floods,” said Natural Resource Specialist James Jylkka of the U.S. Army Corps of Engineers, New England District. He clarified that the Corps uses the terms “flood risk management” or “flood mitigation” because, as Jylkka said, “If there’s a major event like there was in ’55, there’s going to be damage downstream.”

The event in question was the quick succession of two hurricanes, Connie and Diane, in August of 1955 which devastated interior New England, especially Northwest Connecticut. According to the National Weather Service (NWS), the event was so destructive because the first storm, Connie, saturated the ground, which Diane then dumped up to 20 inches of rain on top of a week later. It was a very similar set up to that which caused the catastrophic flooding in the Southeast from Hurricane Helene in September.

According to the NWS, Connecticut suffered the biggest losses from that event in New England, with 77 lives lost and over 350 million dollars in property damage. Matthew Coleman, operations manager of the Naugatuck River Basin with the Corps, maintained that major flooding from large hurricanes during the 1930s and 1950s was the major impetus behind the Corps reservoir program in New England. Coleman and Jylkka confirmed that the Colebrook River Dam, which stops up Colebrook River Lake (and hides the now-submerged lost village of Colebrook River), was built as a result of the 1955 floods. The dam was finished in 1969.

Jylkka was careful to point out that floods and storms are contextual. The dam regulates its water level throughout the year – on the day of the outing, the water was quite low, which is typical Jylkka said – and so if a storm like 1955’s that arrived in fall when the water was low, it might not have such disastrous impacts. Should it arrive in spring with high water, it could be devastating.

“It doesn’t take a major hurricane to cause this devastation,” he said, referring to the events of 1955. “It’s site specific and context specific.”

An example of this was the flooding along the Little River in August which claimed three lives and wreaked havoc upon the town of Oxford and downstream municipalities. The flooding resulted not from a hurricane, but from a series of slow moving, drenching thunderstorms that dropped enough precipitation that many thought the storms might have overtaken Diane’s current record for 24-hour rainfall. After review, Diane still holds the record, but the damage from the storms remains — Route 34 in Oxford only reopened on Oct. 16, nearly two months after the floods.

Coleman said that the stretch of river which flooded in August is not under the Corps’ management – on that day, “our reservoirs did do their jobs.” However, Jylkka maintained that waterways are complex systems, and many watersheds are not under the Corps’ management. Many reservoirs are managed by drinking water firms who like to keep the reservoirs full, thus making them flood prone, Jylkka said. Even flooding in Vermont could have impacts in the Northwest Corner, he said.

For their part, the Corps has “a laundry list of stringent requirements” that keep their watersheds very well managed, Jylkka said. Coleman assured that the Corps has “a whole team of professionals on the ground in the New England District,” both doing boots on the ground maintenance and operation alongside a team of engineers monitoring weather and flow conditions.

As climate change brings wetter and wilder storms to the region, Jylkka suggested that residents “be smart and be prepared – It is more critical than ever for people to be aware of their surroundings.”