Stevenson Dam: Older than your Grandma

The Stevenson Dam’s life force is the Housatonic River. The Housatonic is a 149-mile river beginning in Western Massachusetts, flowing through Western Connecticut and emptying into the Long Island Sound. (1)

In 1890, the toll house connected to the bridge on the Oxford side was ordered to be taken down, as it was a fire hazard to the bridge. (5) In 1899 the Housatonic Power Company began dreaming up plans for a powerful dam to utilize the river to produce electrical power for the surrounding areas and lessen dependence on coal. (6)

In 1917 a charter amendment allowed work on the dam to begin. Republican Congressman Ebenezer J. Hill from Norwalk held office at the time of the announcement, until his death in September. He was then replaced by Republican Schuler Merritt from Stamford, from November 6, 1917, to March 3, 1931. Today, the fourth congressional district office is held by Democrat Jim Himes (9)

Construction was to begin a half-mile downstream from the location of the Zoar Bridge. The proposed lake bottom was already under survey by the Birkenbine Engineering Company of Philadelphia. Portions of Southbury, Oxford, Newtown, and Monroe were to become inundated. (7) 

Riverside was set to lose homes, schools, churches, summer camps, and a cemetery to the dam. (7) The cemetery was respectfully moved and relocated. (12)

The Housatonic Power company had bought most of the surrounding land before getting the green light on construction. With a history of floods devastating properties and livelihoods in the past, the dam seemed a worthwhile investment to ensure control over the river, despite the loss to some of the towns. (7)

The Stevenson Dam began construction in 1917 with architecture by the Birkinbine Engineering Office and construction by the Housatonic Power Company, which changed names to The Connecticut Light and Power Company and most recently known as Eversource Energy(11). They were racing the clock to complete the dam before their coal supply ran out.

John Babina Jr., a Monroe historian and engineer who worked in avionic systems said in regards to Stevenson Dam, that "It was the most ambitious engineering feat of the East Coast at that time." (12) 800 men were employed to work on its construction. (10) They created Camp Crisfield (12), a little town with a church, carpentry shops, and a hospital for them to live in. Presumably, after the Riverside town was demolished.

The Stevenson Dam is a concrete gravity dam, anchored in a hard bedrock of gneiss. (10) Around 155,000 cubic yards of concrete were used. (8) That’s about 15,500 fully loaded cement trucks worth of concrete being poured. Legend has it a worker fell into the wet concrete one day and never made it out. His sign-out sheet left blank. (10) Some people chalk it up to rumor, but with all that smoke and commotion going on it's not hard to imagine possible.

Construction took two years and cost 5 million dollars (13), worth roughly 77 million dollars adjusted to today’s inflation (15.) The dam was originally designed for power generation, specifically for the New York, New Haven, and Hartford Railway systems. There was some initial dispute as to which side of the river should house the powerhouse, but Monroe had a better bedrock foundation. (10).

The Stevenson Dam opened in the fall of 1919. It stands at 125 feet high and is nearly a quarter-mile across. (8) The dam has a bridge across it owned by the Department of Travel. It is 20 feet above the dam and suspended by 24 concrete piers. The Stevenson Dam Bridge is 23 feet wide transporting Route 34 across the river, connecting Monroe and Oxford counties in Connecticut.

The dam created Lake Zoar. The name of the lake was the source of some controversy but ultimately settled on the name Lake Zoar in remembrance of the Zoar Bridge that once stood there. The reservoir is 1500 acres and its capacity is one and a half billion cubic feet of water. (8)

In 1987, 80 “post-tensioned” anchor cables were bolted to the bedrock to improve the dam's resiliency. This was an engineering update provided to most concrete dams post 1970’s. (10)

At the dam site is the Stevenson Powerhouse. It is a hydroelectric power plant that opened in 1919 along with the dam. At the time it had 3 turbine generators creating a total of 19 MW of power. In 1936 a fourth unit was added and with it 12 more MW. Today, the plant produces a total of 28.9 MW of power. (11)

The recipients of this electric power include New Haven and Fairfield counties. Bridgeport, New Milford, Naugatuck valley from Milford to Waterbury, Danbury, South Norwalk, and other places in Western Connecticut (6).

Unfortunately, a General Electric Factory up the river in Pittsfield Massachussettes routinely dumped PCBs from their factory into the Housatonic until the chemical was banned in the 70s. PCBs are polychlorinated biphenyls, a toxic, colorless, odorless chemical compound. Most of these chemicals are still in the river's sediments today, as they take years to decompose. (1). There are special alerts ranging in severity towards eating the fish from the Housatonic water bodies. The fish have concentrated amounts of PCBs that can be unsafe for consumption.

In the Lake Zoar region specifically, it is advised no one eats the trout, catfish, eel, carp, northern pike. Bass should not be eaten by high-risk groups. Yellow perch, calico bass, rock bass, bluegill, and sunfish were advised to be eaten sparingly. High-risk groups include pregnant women, nursing women, and children under the age of 6. (15)

The presence of PCBs in the sediment in the river affects more than just fishing. Construction for a new bridge upstream of the dam has been denied by the Department of Environmental Protection with concerns of stirring up the chemicals. (1).

The dam bridge as it stands now is over 100 years old. It’s a narrow road with no space for pedestrians to walk and 2 sharp turns to enter which causes accidents. The road is often shut down for repairs as well. (10). A bridge downstream from the dam has been proposed instead, citing less cost, environmental concerns, construction ease, and public acceptance as major factors.(18)

Lake Zoar, which boasts scenic views, 27 miles of shoreline, and seasonal recreational water activities, is nothing short of beautiful. (11) Nearby is the small yet charming Lake Zoar Drive-In. A good place to stop and get a sandwich. It was established in 1993, although the restaurant has been there since the opening of the dam. The modest Lake Zoar Marina sits behind it, renting boat slips during season.

On the Monroe side next to the Powerhouse below the dam, is a small recreational scenic and picnic area with a grill and picnic table. On the outskirts of private property from the Powerhouse is  Webb Mountain Park . There you can camp, rock climb, or hike on one of the many trails in the 135 acres the municipal park has to offer.

Today, the dam is currently managed and maintained by FirstLight Power. (11) Officials at FirstLight have drills with the towns at risk if there were ever to be an accident. Part of Shelton, downtown Derby and parts of Seymour are among those downstream. (10) In 2000 the Stevenson Dam was listed on the National Register of Historic Places, including the bridge and powerhouse. (11) The dam is also one of the few in the US that carries a major highway over it (10).

While the dam is certainly rich with history and enjoyable views, its infrastructure is not meant to last forever. Facades on the powerhouse crumble. Lake Zoar Marina could use a facelift. The bridge is hazardous and countless PCBs lie in the rivers sediment. Yet Stevenson Dam holds a weary charm, despite it all. It’s foundation is strong, but how much longer can Grandma Stevenson Dam hold out?