Tack Factory Dam to be removed 11-10-16

Tack Factory Dam to be removed

By James Kukstis
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Thursday
Posted Nov 10, 2016 at 12:00 PM

Wicked Local Hanover

For the past 342 years, the herring population in the brook that bears its name has been unable to utilize the majority of their natural habitat.

Thanks to work by the North & South Rivers Watershed Association and the Massachusetts Bays National Estuary Program, those fish will be able to access 86 percent of that habitat by next spring.

Work will begin this December to remove the Tack Factory Dam on Third Herring Brook, the dividing line between Hanover and Norwell. The dam is owned by the Cardinal Cushing Centers.

This dam is one of four historic obstacles on Third Herring Brook. The YMCA removed one upstream in 2014, and another further upstream, owned by the Hanover Mall, is the next that the NSRWA would like to remove. The fourth is the Jacobs Pond Dam, which will likely not be removed, but may have a fish ladder installed to aid fish transit.

These dams, which largely serve no modern purpose, segment wildlife habitats by making it difficult, or impossible, for fish to make it through. By removing these obstructions, the fish are able to move further upstream to spawn.

There are more than 3,000 dams in Massachusetts, and only 200 of those serve any modern purpose.

Removal of the Tack Factory Dam has been in the works since 2002, and the $420,000 project is being funded by a combination of federal and state grants, private foundations, and individual contributions.

The earthen dams were constructed in the colonial period to power sawmills and gristmills, and were then rebuilt during the industrial revolution to power factories. This particular dam powered a tack factory, hence its name.

The NSRWA has been systematically lowering the water level in the man-made pond behind the dam over the past few months, which will help for a natural transition once the obstacle is removed.

"People misguidedly think that somehow it's going to flood something," said Samantha Woods, Executive Director of the NSRWA. "A controlled release of that water is what you want."

Woods said that if there was any upside to this year's drought, it was that it made the process of lowering the water level in the pond easier. The newly exposed land is muddy, but is already showing signs of vegetation.

The removal of this dam is a big step in the ongoing project to restore the Brook.

"This dam is really critical," Woods said. "It's the first dam from the North River so it's the first to obstruct anything from the ocean, so fish like herring and eels that migrate from the ocean can't get past this dam right now, and haven't been able to for the past several hundred years."

While the removal and restoration will help a number of species, the herring population is particularly important to restore.

"The species itself is a real keystone species," Woods said. "A lot of different species like to eat this. It's an important part of the ecosystem, and holds up other species. Out to sea, they're eaten by striped bass, tuna: all the things we like to eat. They're a critical sea forage fish, and they're also critical to the ecology of the streams themselves. Lots of bird life wait for this spring run of herring, utilizing this protein to have their populations live."

The NSRWA is fundraising for the next phase of the project, which will monitor the herring populations in the brook by tagging them and tracking their movement. Woods said the results of the removal will be seen as early as next spring, and in four to five years they will be able to fully measure the effect on the herring population.

The removal of the Dam should be complete by January. Woods said that now is the right time of year for a project like this, as it is the lowest part of the stream flow, and it is the time with the least amount of biological activity in the water.

"The herring are a particularly iconic fish. Many of our brooks were named after them. Their populations are really in big trouble. They're ninety percent depleted."

Woods said the herring were under consideration a few years ago to be listed as endangered, but weren't found to be at that level yet. By removing dams and restoring the brook to full stream, the NSRWA aims to help make sure they never get there.

Follow James Kukstis on Twitter at @MarinerJamesK.