South Natick dam defenders rise up before key vote; engineering & financial updates shared

South Natick dam defenders rise up before key vote; engineering & financial updates shared

The town of Natick has involved the public since the start of its formal process to determine the fate of the South Natick dam and spillway (aka, waterfall) that it owns. An advisory committee consisting of town officials as well as members of the public—including some whose properties are near or abut the Charles River—has been meeting since early 2021. Natick has held numerous meetings and surveyed the public to gather input.

But with the Charles River Dam Advisory Committee poised to make a recommendation to the Select Board next month, a group seeking to Save Natick Dam (“this most beautiful spot in Natick”) has increasingly made its presence known. About 700 people have signed a petition as of this writing and yard signs have mushroomed at homes and businesses nearby the dam. The group held a rally on short notice attended by 30 or so people over the weekend, and local news outlets have given the cause attention as well. (Disclosure: We’re river neighbors.)

“In our canvassing of people in the immediate vicinity, the vast majority are unaware a decision is going to be made,” and most are in favor of keeping the dam, says Natick’s Brad Peterson, who is among those organizing the campaign to repair the dam and save the spillway. “Just ask anybody down there now.”

save natick dam


Natick has been deciding between repairing the nearly 90-year-old earthen dam or getting rid of the spillway/waterfall. A viable way to keep the trees atop the dam and the dam itself hasn’t been found. Arguments for ditching the dam relate to safety (it’s a high hazard dam that if unexpectedly breached could cause major damage), ecology, native American history, as well as financial in that the town is looking hard at cost savings as it faces a possible override. Groups such as the Charles River Watershed Association have been pushing hard for dam removal to restore rivers.  Those in favor of keeping the dam and spillway don’t want to lose the picturesque park and rue loss of the “pond” above the dam that will revert to a river expected to be navigable or not by kayaks and canoes based on the season.

As part of the consulting flood during this review process, the advisory committee and public were shown a landscape design firm’s renderings of possible park upgrades under either scenario, though with an acknowledgement there’s no funding for such elaborate makeovers at this point.

Peterson credits the town with holding a public process, but says some issues have yet to be explored fully. For example, while there’s been a focus on returning the river to an ecosystem that existed before the dam, he says there’s been little discussion of the ecosystem that has formed over the years since the dam was installed, including in the pond area above it. There’s also an argument that the spillway, which spans the river, might be aerating the water in a way that benefits the environment. In addition, Peterson says if the town did invest in repairing the dam, it could update it to allow for flood control.

South Natick Dam

“If the spillway is removed, that part of the Charles River will be just like any other part of the Charles River. It will lose that stunning aesthetic,” he says. While acknowledging the trend toward removing dams, and some for good reason, he adds: “Not all dams are equal.”

Engineering viewpoint

The increased activity by dam defenders follows that June 27 advisory meeting (see presentation slides below) during which engineering consultant Stantec, a firm that specializes in dam removal, concluded during its state-funded research that disposing of the spillway is feasible from a regulatory and technical perspective. Stantec has consulted on dozens of possible dam removals, and has completed removals of a dozen Massachusetts dams, some described as “a lot of fun.” Many of its projects have been done in partnership with the Commonwealth’s Division of Ecological Restoration, which advocates for dam removal.

About 12 minutes into the Natick Pegasus recording of the June 27 meeting, Stantec’s Gordon Clark began going over findings from the firm’s site reconnaissance and preliminary design for spillway removal. A final report is being readied for the town by the end of July.

The focus included the water impoundment areas above the dam, with the most significant change anticipated in the area between the current spillway and the private red footbridge—we could be looking at the depth of water during normal flows falling from 6 feet to 1 foot or less. Stantec modeled the likely impact on water depth and flow—a slight increase in speed is expected above the dam—as well as changes to the surrounding land. The river’s width could shrink 20{64d42ef84185fe650eef13e078a399812999bbd8b8ee84343ab535e62a252847} to 25{64d42ef84185fe650eef13e078a399812999bbd8b8ee84343ab535e62a252847} in the immediate stretch above the dam, the firm found.

Stantec reviewed research by another consulting firm called GZA that delivered an earlier dam removal project design of its own, determined the dam was in “poor” condition, and conducted sediment sampling. Stantec did its own sampling and is the first to present a possible design for breaching the spillway.

Few changes are expected downriver, per Stantec, though sediment stored at the dam will head in that direction. Sediment sampling showed some contamination, but Stantec’s Mike Chelminksi said there were no “showstoppers.”

Save Natick Dam’s Peterson would like to see deeper sediment testing, and in fact Stantec has recommended that more sediment research would be needed.

stantec dam summary

Financial angle

Natick Deputy Town Administrator Jon Marshall briefed the advisory committee during the June 27 meeting on the probable cost of repairing the dam-plus vs. removing the spillway. This updates the estimates made more than a year ago with partner GZA, and now includes estimates for maintenance and operations, as well as replacing the fish ladder, which fish have given up trying to scale.

For dam repair, Marshall reviewed one-time engineering and construction costs, such as repairing the earthen berm and replacing the fish ladder. That would total $2.64M. He also reviewed ongoing operations and maintenance costs, including state compliance and preventative maintenance, and this would total  $830K over 30 years.

For spillway removal, there would be one-time engineering and construction costs, including for the spillway demolition and water/sediment management, and that’s estimated to total $1.5M. There would be no ongoing maintenance costs.

So overall, one-time costs would be more than $1M higher with dam repair, plus the town would have the ongoing costs.

We reached out to a town official for clarification on what, if anything, Natick has been paying for dam maintenance, and will update this post if we get additional information.

There are possible outside sources of funding for repair or removal that include state and federal grants.

“We’re good at reaching out and trying to find ways to fund things outside of taxpayer dollars,” Marshall said.

Natick Director of Sustainability Jillian Wilson-Martin said that her team’s research has found that “the scale of the grants that are available for dam removal or spillway removal… are much larger.” Some grants apply to either approach, but you’ll likely score more points with the grant givers if you’re going the removal route, she said, noting that the feds and state are encouraging removals over repairs.

Natick Spring Annual Town Meeting in 2019 approved spending $1.2M for dam repair, but this was before the spillway removal option emerged. In either scenario, the town would likely have to go back to Town Meeting to help cover either the higher estimated cost for dam repair or to introduce the spillway removal option and seek funding.

Regardless of which way the town goes on this decision, it seems clear that the dam and spillway have at least a couple more years of life based on this project timeline presented by Marshall.


dam repair timeline

Discussion continues

The Charles River Dam Advisory Committee is slated to meet on July 19 and 26 to deliberate and then decide on its recommendation to the Select Board. Three-quarters of the committee will need to reach agreement on a recommendation to send to the board.

While the committee certainly seems to be leaning toward spillway removal based on their parting thoughts, Save Natick Dam’s Peterson vows that the group will make a push to further educate the public and the committee in weeks to come.

Ona Ferguson, who has been moderating the advisory meetings on behalf of a consulting firm, said during one transition at the June 27 meeting:

“I think we’re struggling right now and through this whole process with the fact this is a river and we can’t know everything about it or what it will do. It’s not the kind of thing you can answer. We’re trying to learn what we can and imagine what we can together and with the support of people who know rivers with different perspectives.”

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