Dam removal opens waters
Removing unused dams is rare but is becoming more accepted as a way to improve river health, particularly by allowing fish to move back into historic breeding grounds.
The removal of the Merrimack Village Dam will open about 14 miles of the river, from the confluence with the Merrimack River up to a dam in the center of Milford, to fish such as alewife, shad and salmon.
New Hampshire has about 4,800 dams, most of them quite small and few of them serving any purpose. A dozen have been removed since 2001 and seven more are being eyed for destruction, according to the Dam Removal and River Restoration Program run by the New Hampshire Department of Environmental Services.
Nationally, somewhere around 500 dams have been removed this decade, according to national monitoring projects, out of several hundred thousand that exist.
In many ways, the Merrimack Village Dam was an easy one to get rid of.
Originally built to serve a mill, and rebuilt at the start of the 20th century to create a water supply, it has served no purpose for decades. Its owner, Pennichuck Corp., wanted to get rid of it to save maintenance costs and paid half of the half-million-dollar cost.
There were no abutter complaints: Few properties lie along the river between the Everett Turnpike and the Merrimack River, where the water flow would be affected.
Just as important, there were few environmental issues, mostly because the sediment collected by the dam was entirely sand rather than toxin-collecting mud or silt. Some past dam removals, notably the Fort Edward Dam on the Hudson River, released a huge “pulse” of accumulated pollutants and did great damage downstream.