Removal of Potter Hill Dam would improve Pawcatuck River fish passage, reduce flooding risks
By CYNTHIA DRUMMOND/ecoRI News contributor
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| The Potter Hill Dam in Westerly, R.I., was originally built in the 1780s and is failing. (Cynthia Drummond photos) |
Rhode Island residents, state legislators, and municipal officials were recently presented with several options regarding the future of the deteriorating Potter Hill Dam, which once powered Westerly’s Potter Hill Mill.
During a March 18 online public
information meeting, participants applauded the proposal to remove the only
remaining dam on the Pawcatuck River, but some residents worried that removing
the dam would significantly lower the water level of the river, draining
wetlands and impacting wells and property values.
Funded by a $100,000 grant, the
first funding of a multiyear award from the National Oceanic and Atmospheric
Administration (NOAA), the project has received additional monetary and in-kind
donations totaling $112,500.
Participating groups, in addition to NOAA, are The Nature Conservancy, the Westerly Town Council, the Westerly Conservation Commission, the U.S. Fish & Wildlife Service (USFWS), the U.S. Geological Survey, the Rhode Island Department of Environmental Management, the Southern Rhode Island Conservation District, and the Wood-Pawcatuck Watershed Association (WPWA). (The town of Hopkinton borders the river on the other side, however, the study doesn’t have a Hopkinton representative.)
The derelict Potter Hill Mill,
recently the focus of a failed private redevelopment plan, continues to crumble
into the river. The Potter Hill Dam, first built in the 1780s and rebuilt in
the early 1900s, is also failing. Both the dam and the mill are currently in
receivership.
Westerly director of development
services Lisa Pellegrini described the site as “a big, expensive problem,”
which, in addition to posing a public safety hazard, puts the town at an
increased risk for flooding.
“If the dam fails, there will be a
devastating flood that will greatly affect Westerly,” she said.
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| The Potter Hill Mill, built of Westerly granite in the 1840s, is collapsing into the Pawcatuck River. |
Water resources engineer Nils Wiberg, of the Providence-based environmental engineering firm Fuss & O'Neill, presented a technical overview of the study, which evaluated several options for removing part or all of the dam.
The project will be the final step
in an initiative that began a decade ago with fish passage enhancements at the
Lower Shannock, Horseshoe Falls and Kenyon Mill dams, followed by the removals
of the White Rock and Bradford dams.
“So here we are at Potter Hill dam,
which is, I’ll say, the last significant barrier to upstream migration,” Wiberg
said. “There is a fish ladder there. That fish ladder is probably on the order
of 30 or 40 years old.”
The existing fish ladder is outdated
and largely ineffective. Migrating fish, such as river herring, crowd together
as they attempt to navigate several millrace channels searching for the fish
ladder, and become easy prey for cormorants and gulls.
The dam’s spillway also poses a
hazard to paddlers, who must portage their kayaks and canoes, but the greatest
threat, Wiberg said, is the dam suddenly collapsing altogether.
“If those gates were to give way
during a storm or a flood, the whole upstream region of the river could be
drained in an uncontrolled manner,” he said.
Engineers and scientists have
analyzed every aspect of the river and the dam, from water flow to the river
bottom, sediment transport, and nearby bridges and wetlands. They considered
several options before arriving at their preferred course of action: removing
the dam and returning the river to its natural state with a low-flow channel
created for fish passage.
During the meeting’s public comment
period, several residents said they were concerned that their shallow wells
might run dry when the water level drops by a projected 3-5 feet.
Sen. Dennis Algiere, R-Westerly, and
Rep. Brian Patrick Kennedy, D-Hopkinton, said they had received calls from
constituents afraid that their shorelines will become several feet of muck.
“They’re very concerned that this will
not only take away their current riverfront location, but also significantly
lower the value of their homes,” Kennedy said.
Hiscox Road resident Brian Tarpey
said he worried about losing the wetlands.
“These are going to disappear,” he
said. “You can say you’re turning it into scrubland or whatever you want, but
you’re taking several hundred acres of wetlands and destroying them.”
Before the recent meeting, WPWA
executive director Christopher Fox told ecoRI News that the objective was to
restore the river and wetlands to their natural state, which would, in turn,
mitigate flooding.
“You’re restoring the floodplain of
the river to its natural characteristics,” he said. “Think of it this way: the
dam is flooding the floodplain as though we were experiencing heavy rainfall,
because it’s a manmade block across the river. Take the block out, and now the
floodplains are no longer just standing water. They’re dry land waiting for
flood waters to come.”
USFWS biologist Suzanne Paton said
the removal of the dam would improve fish passage and help turtles.
“The whole Wood-Pawcatuck watershed is a high priority for the Fish and Wildlife Service because we know it’s such an important river for fish passage, and also for wood turtles and spotted turtles, which right now are being proposed for federal listing,” she said.
“We’re really concerned about turtle populations and we have really good
habitat for wood turtle and spotted turtle in the Wood-Pawcatuck watershed.
It’s a nice healthy river system for the most part. Just having the river
connected and open and flowing naturally so that species can move up and down
river at will and not have to get out and cross the road is always just
fantastic.”
Project planning is expected to
continue through the fall. Questions and comments can be submitted online.
Cynthia Drummond worked most
recently for The Westerly Sun, where for 10 years she covered the towns of
Charlestown, Richmond, and Hopkinton and the Chariho School District.