The Dana Dam was constructed was first constructed by Charles Dana to create a seasonal skating pond and swimming pool for his children.
Pat Tomlinson / Hearst Connecticut Media file photoWILTON — About 80 trees will be removed from Merwin Meadows in the coming weeks as officials prepare to finally remove Dana Dam and reopen the stream, making it easier for fish to again travel the waterway.
Removing Dana Dam has been in the works since before 2008 but stalled due to the economy. Wilton resumed its efforts in 2016, partnering with Save the Sound as the lead project manager a year or two after, said Michael Conklin, Wilton's environmental affairs director. Save the Sound also received federal grants to hire a contractor to complete the work, making it a reality.
"A natural, free flowing river ultimately will be better for the environment," Conklin said.
The removal will be done in phases beginning with the tree work this month so the equipment can get to the dam. A temporary roadway will be built on one side so vehicles can enter the site, he said.
Alex Krofta, Save the Sound's ecological restoration projects manager, said this timing is to protect the endangered northern long-eared bat, which begins raising its young in trees in April.
"Save the Sound, Wilton, and the contractor are committed to cutting as few trees as possible," Krofta said, adding they might not need to remove all 80.
The Mianus Chapter of Trout Unlimited has agreed to plant two trees for each tree that is cut down to restore the area at the end of the project, Conklin added.
"In the short term, the area will look very different," he said. "It could look decimated to some people."
Conklin said that is just because the current trees are mature, while the replanted ones will be smaller.
Some site work will occur in the spring and most of the construction and demolition will happen during the low summer flows in the Norwalk River, with completion expected in the fall. The dam itself will be taken down last using a jackhammer mounted on an excavator, Krofta said.
The new stream channel will have pools, riffles, banks and floodplains with native vegetation, Krofta said. Part of the existing channel will also be rerouted away from the railroad embankment to reduce stream pollution and create more stability for the railroad.
"The site will go from an artificial concrete waterfall and unnatural pond — really, an 'impoundment' — back to a flowing stream," he said.
Krofta said the dam must be removed because it traps sediment that flows downstream creating riverbed habitat, as well as blocks the passage of fish and other organisms.
"Dams impair water quality by creating large, stagnant 'impoundments' that have low oxygen levels and warm water temperatures, which are harmful to fish and other aquatic life," Krofta said.
He added that most dams don't prevent or reduce flooding, but increase the risk of it through possible dam failure and reducing natural flood plains. Dana Dam, in particular, is a high priority because it is the first barrier upstream from Long Island Sound preventing migratory fish, such as eel, lamprey and river herring, from getting to the spawning habitat in the upper stretches of the Norwalk River.
Krofta said removing the dam should make about 10 river miles of habitat available to those species, "whose return will support populations of dozens of species of fish, birds, and other wildlife."
He said it will also create new vegetated riverbanks and floodplains which are important for clean water and wildlife habitat.
There are other dams in Connecticut being removed, including Kinneytown Dam in Seymour and the Lower Collinsville Dam in Avon and Burlington.
Anthony Allen, Save the Sound's restoration strategy director, said dam removal is becoming widely accepted and encouraged for ecological restoration.
"Connecticut has the most dams per river mile of any state in the nation, with more than 5,000 structures disrupting the flow of our rivers and streams and segmenting habitat for fish and wildlife," Allen said. "Most of these dams no longer serve a purpose, and are not regularly or properly maintained, resulting in an increased risk of dam breach or failure."
kayla.mutchler@hearstmediact.com