Assabet River group eyes removal of old dams; Federal report due this year.

Byline: Pam Pollan 

The Organization for the Assabet River is exploring the idea of removing several old dams on the river in anticipation of an Army Corp of Engineers' study due out this year that will make recommendations on dam removal along the Assabet.

The organization held a workshop on the subject March 14 at the Forbes Municipal Building in Westboro. The workshop gave an overview of the progress that has been made in restoring the health of the Assabet River and the challenges that remain. The river, which stretches nearly 31 miles from Westboro to Concord, has seven former mill dams and two flood-control dams, according to OAR's Web site, www.assabetriver.org.

"A lot of people don't realize there are that many dams on the river," OAR's Policy Director Alison Field-Juma said.

Northboro is home to two old mill dams - the Aluminum City Dam, or Sawmill Dam, near Route 20, which was built in 1925; and the Allen Street Dam, or Woodside Dam, near Hudson and Allen streets.

The dams in Northboro are fairly small and go mostly unnoticed, except by people who live nearby or who paddle the river, Ms. Field-Juma said.

"The dams are always full. The water is almost always up to the brim. If there is additional water, the extra water spills out," she said. "Those old mill dams are not being used to manage the water level. They're just sitting there full. So if you remove them, the river level would be lower because the water wouldn't be all pooling behind the dam. If you remove the dam, the water level will drop, which would actually reduce the chance of flooding."

The Nichols Dam in Westboro, built in 1968 by the U.S. Department of Agriculture's Soil Conservation Service, was designed to aid with flood control and fish and wildlife development, according to OAR's Web site.

"The big picture of this is Westboro's wastewaster treatment plant discharged into the water at the headwaters of the river. That has an impact on the river, in part because the dams trap nutrients and they feed the aquatic weeds," Ms. Field-Juma said. "Wastewaster conveyed downriver can be cleaned up, and even though this is happening this doesn't totally solve the problem because nutrients behind the dam are recycled over and over."

The goal, she said, is to restore the river to its natural, free-flowing condition by not only removing dams, but planting native vegetation and putting in the right kinds of rocks. Ms. Field-Juma said this would help to improve the water quality to a level the state deems swimmable and fishable.

"The term fishable not only means that you can fish in the river, but that it is also a healthy habitat for the fish and all wildlife," she said.

One alternative to dam removal is to require wastewater treatment facilities to discharge fewer nutrients.

"If you do nothing about it, it's probably going to get worse. In the short term, we hope to see some improvements because all of the wastewater treatment plants are being upgraded. But in the long term, because of climate change, we can expect there will be more dry summers and the water will get hotter, and that will make the problems of the river worse," Ms. Field-Juma said. "We want to take a very broad look at all the options that are available."

ART: PHOTOS

PHOTOG: T&G Staff Photos/PAUL KAPTEYN

CUTLINE: (1 AND 2) The Allen Street Dam in Northboro is one of several dams on the Assabet River that may be removed. (3) Mallard ducks swim above the Aluminum City Dam in Northboro, one of several dams eyed for removal. (4) An icicle hangs from a large log overhanging the Allen Street Dam in Northboro.