RWA photo
Lake Whitney Dam: Ready to be improved for “the next 160 years.”
The Lake Whitney Dam on the border of New Haven and Hamden has been going strong since 1860, when Eli Whitney and the city built it. But it’s in need of rehabilitation — a major construction project — to prepare it for the climate challenges of the next century and beyond. That can be done while also keeping an eye on the community and environmental concerns of the present.
That was the message from Lawrence Marcik, Regional Water Authority (RWA) capital program lead and dam engineer who has been working on it for “most of my career,” and Sunder Lakshminarayanan, vice president of engineering and environmental services, at a meeting Monday morning attended by around 20 community members.
The online meeting offered the RWA’s latest update on its progress to rehabilitate the Lake Whitney Dam, a project that has been years in the making.
The rehabilitation project’s goals are to improve the dam’s structural stability generally, better control seepage (which happens “with all dams,” Marcik said), and improve the dam’s ability to withstand the “probable maximum flood,” which Marcik estimated at about a foot of rain a day for three days. All of this, the team emphasized, is to be done while also attending to environmental and community concerns, including historic conservation and protection.
The construction work itself entails a few challenges. The Mill River’s water flow still needs to be managed. The nearby water treatment plant needs to receive enough water to stay operational. Existing utilities need to be protected. And the project’s plans must pass through several authorities — the city of New Haven, town of Hamden, state Department of Energy and Environmental Protection, federal Environmental Protection Agency and the Army Corps of Engineers — before construction can begin.
“It’s time for the dam to be upgraded” to meet the needs of “the next 160 years,” Marcik said, and “given climate change,” its capacity needs to be improved.
Another in-person meeting will be held on Thursday, June 13, at 6 p.m. (RSVP at whitneydam@rwater.com). The next meeting after that will be held in the early fall, offering further detail on the steps the RWA will take in this complex project, from building a temporary dam upstream at Davis Street to doing construction behind the existing dam at the border of New Haven and Hamden.
The Lake Whitney Dam is one part of the larger scope of the RWA’s work. Its 270 employees oversee 140 square miles of watershed, treating 45 million gallons of water per day for 430,000 customers in 15 towns. The water treatment plant on Whitney Avenue is one of 11 plants, and the Lake Whitney Dam one of over 31 dams, the RWA owns and runs. The Lake Whitney Dam is the oldest of them. It was completed in 1860, “before Abraham Lincoln became president,” said Marcik.
The dam was built under an agreement between entrepreneur Eli Whitney, a contractor (W.C. McCullen and Son), and the New Haven Water Company, predecessor to the RWA. Thanks to the dam, Whitney got hydropower to run his arms factory (just in time for the Civil War) and the city of New Haven got a source for potable water and fire protection.
The dam is “largely unchanged” since 1860, Marcik said, though it has been modified. Six years after it was finished, Whitney and the city added an additional four feet to the structure to increase capacity. In 1917 the dam was raised again, and the spillway — where the water flows over the dam — elongated to its present length of 250 feet.
Still from Regional Water Authority
Covered bridge in East Rock Park during the flood of 1982.
The second half of the 20th century saw the installation of intake towers, underground pipes, and a pressure release valve to account for large storms. The high water mark for such storms (so far) was a flood in June 1982, after almost 12 inches of rain fell over three days. The Lake Whitney Dam weathered that storm despite having 27 to 29 inches of water spilling over it at the flood’s height. In hindsight, the flood lingers as indicating what the dam should be able to withstand.
At some point, RWA engineers are expecting more rain — much more than what fell in the 1982 flood.
Lakshminarayanan said that the design process for the project is about 45 percent complete. After considering alternatives, the RWA has settled on the general plan of building a temporary dam at Davis Street, which crosses Lake Whitney upstream from the reservoir, to maintain the water in the lake at its current level upstream. The water level behind the dam will then be lowered to a level of 10 feet to allow for construction to happen; Marcik estimated that the lake between the two dams will, for a time, be a stream.
In the Q&A period that followed, questions from community members arose about the design of the dam when it’s finished and the state of the lake during construction, especially its potential as a breeding ground for mosquitoes in the mud flats the lowered water level will reveal. Marcik assured participants that environmental concerns were foremost. Fish and other wildlife would be transported to the lake upstream of the temporary dam as the water level was lowered.
The details of the design have also not been worked out yet, but “the path that we’re taking is the one that preserves the façade of the dam,” Marcik said. The original stone wall, save for a notch cut in it, will remain as it is. “The actual face of the dam and the spillway will not be disrupted or touched,” he said. “All the construction is on the upstream side.”
Actual construction likely will not start for a year and a half, due to the necessity of getting permits for the work, especially from the Army Corps of Engineers. Once construction is allowed, the project will likely take years to complete.
“We are in the mode of fine-tuning the design,” Lakshminarayanan said. As they run their plans by local, state, and federal agencies, “all of those entities will give input. It’s going to be a very holistic approach.” But “we want to make sure we listen to the concerns of the community,” and community members’ concerns are issues “we’ll start getting into the weeds about” as the design proceeds.
“There will be a lot more community meetings,” he said. “We would like to keep this communication a two-way street.”
Marcik echoed his colleague, encouraging community members to reach out to him. “It’s my pet project, so I’ll be here for the end of it,” he said.
The next community meeting about the Lake Whitney Dam Project is on Thursday, June 13, at 6 p.m. RSVP at whitneydam@rwater.com for location.