Experts explain Ipswich dam options based on study
Wicked Local Ipswich
By Dan Mac Alpine
ipswich@wickedlocal.com
Posted Dec 19, 2018 at 4:50 PM
Updated Dec 19, 2018 at 4:54 PM
Removing the Ipswich Mills Dam would likely lower water levels from the dam to the railroad bridge between a foot and two feet, dam experts said at meeting last week, but dam removal would improve the river ecologically, especially for fish.
Groundwater levels would drop about a foot, up to 100 feet from the river, in the affected area, however the Ipswich River would remain navigable to canoes and kayaks in all but the most extreme drought or low-water conditions experts said.
“You won’t find a better fish ladder than the one at the dam now,” Ben Gahagan, of the Massachusetts Division of Marine Fisheries, said. “Dam removal is a better passage than the fish ladder.”
A crowd of a about 200 filled Room A in Town Hall last Thursday night and heard results of a preliminary feasibility study on dam removal, with the majority favoring removal according to stickers participants placed on folding topic boards at meeting’s end.
“I want to make clear we have no plans to remove the dam,” said Senior Planner Ethan Parsons, who served as a project manager for the study. “We are conducting a feasibility study.”
The dam, a head of tide dam, is at the Riverwalk footbridge.
“We have a lot more process before a decision is made,” said Wayne Castonguay, executive director of the Ipswich River Watershed Association.
The town currently owns the dam and would make the decision to keep it or remove it.
Other presenters included Castonguay and Neal Price of the Horsley Witten Group Inc. that authored the preliminary study.
Study funding came from the National Fish and Wildlife Foundation, the National Oceanographic and Atmospheric Administration, the Massachusetts Department of Fish and Game, the Massachusetts Environmental Trust and the U.S. Department of the Interior.
Study findings included:
The dam currently blocks anadromous fish from moving upstream, such as American shad, that live in salt water and spawn in freshwater, despite a fish ladder at the dam
A dam has been at the location since about 1635 and the current dam, which is in good shape, is over 100 years old, with liability likely to town taxpayers if dam failure causes damage down stream.
Removing the dam would have little to no impact downstream including on the Choate Bridge or on shellfish beds.
The dam no longer serves the purpose for which it was originally built, to provide power to a mill next to it, and lacks the height to produce electricity; EBSCO now occupies the former mill site.
Lower water levels may require monitoring of or repairs to an existing EBSCO building closest to the Ipswich River and more study is required to determine whether or not a portion of the building is on pilings that would rot if exposed to air.
Saltwater would likely flow up to about the railroad bridge, if the dam were removed, however more study is required to determine water salinity and how far ocean salinity would flow up river; the current dam blocks tidal influence from moving upstream.
The dam currently creates a pond-like system in the river from the dam to about the railroad bridge, Castonguay said and “degrades” the river’s water quality, its ability to support anadromous fish by “impeding” the fishes’ progress upstream and causes general “ecological” damage.
The Ipswich River Watershed Association favors removing the dam.
The canoe entry water level, at the end of Peatfield Street, would drop, especially during low-flow conditions, Price said.
Responding to resident questions about invasive species, especially plants, taking land the dropped water level would expose or of increasing taxes for those who live along the Ipswich River, from the dam to about the railroad bridge, because they would have more land, experts said such concerns were unfounded.
Native plant seeds now dormant in the soil would likely sprout and support a wide variety of birds and wildlife, the experts said.
Any exposed soil would likely be more like a wetland than usable, dry land, Neal said and a reason why no other dam removal like this resulted increased land or property taxes for homeowners.
Neal said those concerned about the dam removal should visit Exeter, N.H., a community that recently removed a similar dam on a similar river and offered to lead fact-finding tour there.
“This river will never return to pristine conditions,” Casonguay said, partly because of the water withdrawals upstream. “We’re working to improve conditions and give species a chance.”
]]>