Stevenson Dam celebrates 100 years

September 6, 2017

MONROE — It was 100 years ago this fall that excavation began on the Stevenson Dam, still one of the largest dams in Connecticut and one of the most complicated civil engineering projects ever attempted in the state.

It’s a project that’s still talked about today, with its share of urban legends, frustrated motorists, wildlife and grand views, particularly after a day of heavy rain.

“It was actually a project of what was then the New York, New Haven and Hartford Railroad, said John Babina Jr., a member of the Monroe Historical Society. “In the early 20th century, the railroad was looking for way to power its new electric locomotives.”

Back then the nation was mostly powered by coal. In late 1916 the country was plunged into what was called a coal famine, and there were worries that not only would there be no coal for industry, but no coal for home heating.

Ships, trains, factories and just about everything else ran on coal, directly or indirectly.

“At that time, people were scrambling for another source of power, and the Housatonic River was seen as being part of the solution,” Babina said.

As the project in the Housatonic River was just getting under way, a battle was brewing between Oxford and Monroe over which side would get the powerhouse, because getting the powerhouse would mean snaring a big taxpayer. At first, Oxford seemed to have the upper hand.

“But after they took a look at the bedrock, there was no choice but to put the powerhouse on the Monroe side,” Babina said. The powerhouse is still Monroe’s biggest single-site taxpayer, according to First Selectman Steve Vavrek.

Construction began in the fall of 1917 after the company now known as Connecticut Light & Power was created to build it. Today, CL&P is the biggest electricity supplier in the state. It no longer owns the dam and its powerhouse; now it’s owned by FirstLight.

The bridge, grudgingly supported atop the spillway by 24 concrete piers, is owned by the state DOT, carrying Rt. 34 between Monroe and Oxford.

More than 800 men aided by dozens of mules worked on the project. Many lived there, creating a tiny temporary city, complete with a small hospital, a chapel, a 300-seat mess hall, carpenter shops and a machine shop. The men worked “night and day” according to a speech given by Gov. Marcus H. Holcomb in the fall of 1919 at a press conference staged at the construction site.

Officials point out that the dam is designed for power generation, not flood control. It can’t hold back floodwaters; the water that enters Lake Zoar — the 1.45 square-mile lake created by the dam — soon finds its way through or over the Stevenson Dam.

They also say that — contrary to popular belief — Lake Zoar does not have a lot of water. The dam is kept in good shape, but even if it were to somehow catastrophically fail, there would be only minor flooding experienced downstream.

The dam is anchored in gneiss, which is very hard bedrock.

So strong is the rock that the gravity-type dam wasn’t physically anchored to the bedrock until 1987 when 80 “post tensioned” anchor cables were installed to give the dam improved resiliency in the event of a major earthquake. Hundreds of concrete dams in the U.S. were similarly stabilized beginning in the late 1970s; this work is ongoing.

Another commonly held belief is that there’s a body of a construction worker encased the dam, a poor soul who fell into the wet concrete.

“No record of that,” Babina said. “That legend began with a report of a man who signed in but never signed out. He probably just took off.”

There have been plans to replace the dam’s bridge with a proper stand-alone bridge about 250 feet upstream from the dam, but this idea, surprisingly, was met with local opposition.

The roadway has to be shut down frequently for repairs, sometimes for days at a time, and the sharp corners at both ends have seen countless crashes over the years. There’s no space for pedestrians, and two tractor-trailers traveling in opposite directions barely have room for each other.

It’s among a small number of dams in the United States that still carry major highways on their backs. Officials throughout the years have said the two make for odd bedfellows because dams and bridges present their own engineering challenges.

The Hoover Dam, spanning the Colorado River between Nevada and Arizona, closed its highway for good in October 2005, when the new Colorado River Bridge, carrying Route 93, opened.

Lake Zoar gets its name from the corner of Newtown and Monroe that once called itself Zoar, after the Biblical city Zoara near the Dead Sea.

At a recent visit, a pair of bald eagles could be seen wheeling overhead, looking for dazed fish that found their way through the dam’s four turbines.