If three privately-owned dams were removed from Andover's stretch of the Shawsheen River, canoers could paddle the length of Andover and native fish the river has not seen in more than 100 years could return.
This is the hope of conservation experts and a team of engineers who has spent the last year studying the Shawsheen, engineering the removal of the dams and its impact on the watershed.
A public forum will be held on the project, which is roughly one-third complete, on Wednesday, Dec. 2 at 7 p.m. in the Public Safety Center, 32 North Main St.
"These are the only dams that are on the Atlantic side of the Merrimack. From an ecological standpoint, if the dams were taken down, it would create a habitat for fish that haven't spawned in the Shawsheen for hundreds of years. It would also create the opportunity to canoe from Tewksbury to Andover and all the way to the Merrimack," said Bob Douglas, Andover's conservation director. "It would be the first time water flowed, uninterrupted, since before these very old dams were installed."
The three dams in the study are the Ballardvale dam near Andover Street, the Stevens Street dam near the Post Office and Marland Place and the Balmoral Street dam. The Stevens Street dam is owned by Atria Senior Living Group and the Balmoral dam is owned by the Balmoral Condo Association, while the Ballardvale dam is owned by two abutting companies.
The dams, built during the 19th century era of mills and industry, are no longer used. The Ballardvale and Stevens Street dams were built to harness water power; the Balmoral was built as an ornamental dam by mill tycoon William Wood, said Douglas.
Now more than 100 years old, the dams pose a liability and are costly to maintain, he said.
Douglas stressed that ultimately, the dam owners "are in the driver's seat" of the removal process.
"Any dam removal would have to go through the permitting process, and we're still in the fact-finding process," said Douglas.
There is also the potential for grant money or funding from state and local agencies to remove the dams, said Douglas.
Next week's meeting will have a presentation on the project as well as open discussion and a question-and-answer session.
Thomas Ardito, president of the Center for Ecosystem Restoration, said his engineering firm will work on historical review, permitting and designing the dam removal through 2010, with possible removal of the Stevens Street and Balmoral dams in 2011.
The Ballardvale dam would be removed later, Ardito said.
Dam removal must be carefully engineered, he said, accounting for changes in water level, sediment buildup and effect on area storm drains, bridges and other infrastructure.
"These dams are in urban areas, and in some cases there are wetlands that are created or modified by the dams. There is a lot of engineering that needs to be done, to create the kinds of habitats we're looking for," said Ardito. "We've done quite a lot of surveying of the river, and determining how things will look when the dams come out."
An open meeting about the dam removal project was held in December 2008, and discussion became heated with some residents in attendance concerned the dams' removal would cause flooding to their homes or reduce the water level to a trickle.
Ardito said neither scenario would occur if the dams are removed.
"The volume of water coming downstream is not affected by dams," he said. "Yes, certainly the removal of the dams will reduce the depth in some parts, and certainly the width. But this is naturally a pretty shallow river ... Look at the areas between the dams and you get an idea of what it would look like without the dams."
The Shawsheen River flows 25 miles from Concord to Lawrence, where it meets the Merrimack River 30 miles from the Atlantic Ocean.
The target species in the dam removal project are herring and shad, said Ardito, and fish that migrate between fresh and salt water to spawn. Herring and shad are ecologically important, he said, because other species of birds and marine wildlife depend on them, and will populate a habitat where they thrive.
"Dam removal improves water quality, stream temperature and leads to a more healthy and diverse ecosystem," said Ardito.
For more information on the Shawsheen dam removal project, including a completed feasibility study, visit www.ecorestoration.org
