Before humans built water wheels and dams to harness the Shawsheen River's power, for thousands of years the river ran unimpeded into the Merrimack River and, eventually, the Atlantic Ocean.
Such conditions could make a return in Andover, but not before experts, town officials and residents weigh in on the potential impact of removing the Shawsheen River's three remaining dams through a study now underway.
Removal of the three dams — adjacent to Stevens Street near Marland Place, Balmoral Street near Shawsheen Square, and Andover Street in Ballardvale — could allow for increased recreation and wildlife in the river. But the effect on abutting residential and commercial properties is also a concern.
"The river had run free for all those years," said Burt Batcheller, a member of the Shawsheen River Watershed Association. "Dams are temporary things. If you look at the big picture of it, yeah, (dam removal) will affect the environment. But they're affecting the environment now."
The Shawsheen River dam feasibility study officially began last week with an initial meeting between town officials and consultants. Letters were sent to all river abutters informing them of the work planned for this summer.
"It's trying to figure out whether removing the dams is a good idea or not," said Batcheller of the study. "I don't know if everybody is going to agree on what's ultimately done."
In addition to the dam study, two town-sponsored canoe trips are planned this weekend on the Shawsheen River.
On Saturday, May 17, members of the Shawsheen Renaissance project task force and Shawsheen River Watershed Association will explore the river with residents near Shawsheen Square to examine firsthand the future of recreational opportunities there. The renaissance project is looking to make significant longterm changes to the Shawsheen square area.
On May 18, the Conservation Commission is sponsoring a spring hike and canoe trip in the Lowell Junction area.
"It's going to be a fun weekend on the river," said Town Planning Director Paul Materazzo.
According to the dam feasibility study manager, Marty Melchior, also the regional director of Interfluve, a private river restoration design firm, during the next 10 days two workers will collect topographical data of the Shawsheen River and its banks. The data will guide discussion concerning the river's future, he said.
"It really helps us to create a base map," said Melchior. "It really is for construction type of drawings."
Melchior said preliminary engineering this summer could eventually lead to a final design for dam removal, but not before several months of public involvement takes place.
"With these projects there's a tremendous amount of social interaction that has to go on," said Melchior. "You really need to spend a lot of time soliciting public opinion and try to make sure everybody's voices are heard. That can take a while."
Melchior said the removal of a single dam similar to the ones found in Andover generally costs between $100,000 and $250,000. That total can increase if sediment built up near the dams must be removed from the water, he said.
Other than sediment build-up, Melchior said the presence of dams typically warms water temperatures and degrades aquatic habitat by reducing oxygen levels within the water.
Removing the dams would likely restore wildlife habitat, and pathways for both fish and canoes, he said.
"There's quite a long laundry list of negative dam effects," said Melchior. "There's cons of (dam removal), too. Having to deal with all that sediment, you just can't let all that go down stream. You have to talk about removal and the cost with that.
"Part of our study is to look at how much sediment is behind these dams," said Melchior. "We're hoping there's not too much."
The Shawsheen area is known for severe floods, but flooding concerns would potentially be reduced by dam removal, Melchior said.
"They really don't have any ability to store water," said Melchior. "The dams are not flood-control dams."
Removal of Andover's three dams along the Shawsheen River could allow for the reintroduction of many aquatic species like salmon, striped bass and alewife back into the river, according to Conservation Director Bob Douglas.
"That's our wish, to be able to open it up to bring all those fish who have part of their life cycle in fresh water and part of their life cycle in the sea (to) come up into the Shawsheen," said Douglas.
Beyond Andover, Douglas said there are no other dams between the Shawsheen River and Atlantic Ocean.
"It could potentially be a straight shot down through," said Douglas.
"There's enormous opportunity for boating," said Materazzo. "By removing those dams it really expands the river corridor for recreational opportunities."
As part of the Shawsheen Renaissance project, a long-term effort to revitalize Shawsheen Square and its surrounding area, Materazzo said there is potential for boat portages — routes people can use to carry their boats to the river — new riverside trails and a pedestrian footbridge along the river.
"The community has this beautiful amenity that we've really turned our back on for years," said Materazzo.
"It's an underutilized local resource," said Batcheller. "There's a lot of local adventures that can be had on the Shawsheen River."
