Two dams, separated by 200 miles and built 200 years apart, tell the same story. Both span rivers at the heart of their communities. Both served their purpose once — powering mills, driving industry. Both fell into disrepair. Both were classified as hazards, with inspection reports documenting their deterioration.
The Clark Sawmill Dam collapsed during a historic flood in Vermont. The other still stands in Watertown — for now. And while it's not at risk of imminent collapse, the Watertown Dam serves no useful function and has a negative imapact on the region's environment. It's one of thousands of similar structures, across the U.S.: aging dams that remain in place long after their original purpose has disappeared. Many sit upstream from homes, roads and town centers. Responsibility for their maintenance is spread across understaffed agencies and slow-moving bureaucratic processes. Massachusetts alone has more than 3,000 dams. The state says only a handful still serve their original purpose.
A Dam That Serves No Purpose
The Massachusetts Department of Conservation and Recreation owns the 180-foot-long, 8-foot-high concrete structure that spans the Charles River just upstream from Watertown Square. The state's Office of Dam Safety classifies it as having "Significant Hazard Potential" — meaning its failure could cause loss of life and damage to homes, businesses and transportation infrastructure.
The dam generates no power. It provides no water supply. It offers no flood control.
"We generally advocate for the removal of dams that are no longer serving any purpose," said Lisa Kumpf, river restoration director at Charles River Watershed Association. "There are a few dams on the Charles River that do serve a purpose for flood control, and a few others in our watershed that also serve a purpose for surface water intake for drinking water.... But there are many, many defunct dams that we do advocate for the removal of because it promotes ecological health and restoration."
"The Watertown Dam is what's known as a head-of-tide dam," Kumpf said. "It was actually the first dam built on the Charles River, back in 1634. And it was originally a site for an Indigenous fish weir."
The current concrete structure was rebuilt in 1966 after Hurricane Diane damaged the previous dam. The fish ladder was added in 1972.
A Warning From Vermont
The collapse of the Clark Sawmill Dam shows what can happen when warnings go unheeded.
Built on the Winooski River in Cabot, Vermont, the site had hosted dams since Moses Stone erected the first sawmill there in 1797. The stone-and-concrete version that collapsed dated to the late 19th century. By 1997, when the mill stopped operating, the dam had already outlived its purpose.
In 2006, a river management plan concluded the dam threatened downstream property. By 2016, engineers were more direct: the dam and mill works were in ruins and needed removal to improve public safety.
But removing a dam is not simple. A FEMA buyout fell through after Tropical Storm Irene. The Vermont River Conservancy couldn't reach a deal with the landowner, who wanted more for the property than it was worth.
The dam remained standing when July 10, 2023, arrived.
The Day Everything Changed
In early July 2023, Vermont's ground was already saturated. June rainfall had run one to two inches above average. On July 7, flash flooding near Killington dropped more than four inches of rain. By the next day, soil moisture levels exceeded the 98th percentile.
Then a slow-moving storm stalled over the state. Rain fell continuously from July 9 to 11, dropping three to nine inches of precipitation.
On July 10, the rain-swollen Winooski River surged through Lower Cabot. The Clark Sawmill Dam could not hold. No one was killed. But the river was fundamentally changed.
Michele Braun, executive director of Friends of the Winooski River and a member of the Clark Sawmill Dam working group, warned that the collapse will permanently alter the river's behavior.
"It will result in a much deeper stream channel," Braun said. "That means the stream is less connected to its floodplains. Unable to spread out during future rainstorms, water will move faster and with more power, increasing flood risk downstream."
Jennifer Miner, Cabot's emergency management director, lives just upstream from where the dam once stood.
"We all look like we have the Grand Canyon in our backyards," Miner said.
Understanding the Risk
Clark Sawmill Dam shows what happens when warnings remain unresolved. Similar conditions exist in Watertown: aging infrastructure, documented concerns and a review process stretching across years But a dam's classification can be confusing. "Significant Hazard Potential" sounds alarming. But Kumpf said the terminology refers to what could happen if a dam fails — not how likely failure is.
"There's a hazard potential classification, but then there's also a condition rating," Kumpf said. "The dams that have the most issues for failure during extreme storms — which are getting more frequent in the Northeast with climate change — are high hazard potential, poor quality dams."
Watertown Dam has significant hazard potential, one grade below high hazard. Its condition rating has improved over time. In 2016, a state inspection rated the dam in "Poor" condition. That rating triggered concern among river advocates and helped prompt a formal feasibility study. By 2021, the dam's condition had changed to "Fair." According to Massachusetts dam safety standards, a "Fair" rating means the structure is functioning as intended but has notable maintenance and operational issues requiring continued monitoring. The change happened after the state completed repairs and maintenance work recommended in the 2016 inspection. More recently, Kumpf said, additional upgrades have further improved the rating.
But that doesn't mean advocates think it should stay.
"The real incentive for removing Watertown Dam is for promotion of biodiversity and habitat space," Kumpf said.
Who Would Be Affected
Downstream of Watertown Dam is Watertown Square — the center of town.
"In the case of a breach, which again I think is pretty unlikely, that would be the area that would be flooded," Kumpf said.
She pointed to 2010, the most recent major flooding event affecting the Charles River watershed. Water flooded areas throughout the watershed for several days in April. At Watertown, the dam didn't breach, but floodwater went around it.
"That would probably be the more likely scenario if there were another extreme event like that," Kumpf said. "It would flood the roads that are around the Charles — California Street on the south side. A little bit further downstream of the dam is Watertown Center. Galen Street is one of the major crossings for vehicle traffic of the Charles River in that area. So that would be a huge issue."
"I've been there on times when we've seen the flooding around the banks of the Watertown Dam and that whole little park that's set up on the side gets covered over with water," said Hartman Deetz, a Mashpee Wampanoag tribal member and advocate for dam removal. "So it's not preventing flooding. It's actually causing flooding."
Climate change is making these scenarios more likely.
Hartman Deetz, who has witnessed flooding at the dam site and advocates for its removal
"We have not seen the worst of the storms that we're going to get, for sure," Kumpf said. "We are getting wetter in the Northeast with climate change. And we might see things that are happening in the Charles system that we haven't seen in the past."
Amber Siegel, senior restoration manager at Charles River Watershed Association, said removal could actually improve flood management.
"One of the benefits of removing that dam, especially from a climate resiliency perspective, is when we take down that dam, it can actually improve natural flood management," Siegel said. "In taking out that dam, we reduce the starting point for that flooding, and in lowering that, that means there is more space for that water to overflow when a storm event happens."
"Free-flowing rivers are critical to climate resilience because they allow floodwaters to spread out naturally across floodplains, reducing downstream damage during extreme weather brought on by our warming planet," said Ali Hiple, policy manager at Conservation Law Foundation.
The Fish That Can't Get Through
Every spring, migrating fish attempt to pass through Watertown on their way upstream. A fish ladder exists. But it doesn't work for all species.
"The ladder only works for herring — in the Charles, that's really the blueback herring and the alewife herring species," Kumpf said. "While a lot do get up there, the ladder is actually on the wrong side of the river. It's on the shallow side, so it makes it harder for the fish to find the ladder in the first place."
American shad, a key species present in the Charles River, cannot use the ladder — it's not the right size. Rainbow smelt are too small to use the rungs.
"When we remove a dam like Watertown Dam, which is blocking a few key species including American shad and rainbow smelt from getting further upstream, we remove those barriers and open up more potential spawning habitat for those species," Kumpf said.
400 Years of History
Before European colonization, the Charles River flowed freely to the sea. What is now called Back Bay in Boston was a tidal marsh where Indigenous people built networks of fish weirs to harvest migrating herring and shad.
Deetz described a river of abundance.
"It was such a great abundance of fish in that area that it was really actually a no-man's land where a lot of local tribes could come and partake," Deetz said. "It was a coming together place. It was a crossroads. It was a means of trade."
The herring runs held deep cultural significance.
"In the spawning season, they said the rivers would turn black with the herring because there were just that many of them," Deetz said. "As you got through that lean time of winter, one of the things that showed you that spring was coming back was the herring coming up the river. That's the mark of our new year."
The fish sustained communities through winter and fed the soil in spring.
"One of the first things before you even plant seed, you put that old herring into the ground to fertilize the soil, add that nutrients back in and feed the earth," Deetz said. "That's why it's the beginning of our new year. It's when life returns."
The Watertown Dam disrupted this cycle almost immediately — and was protested from the start.
"It was the first dam put onto the Charles River and it was protested against and people wrote letters of complaint to the Massachusetts Bay Colony even as it was being introduced back in the 1600s," Deetz said. "It was objected to then. It has been objected to ever since."
In 1783, the dam was raised several feet to increase power yield, completely blocking spring fish runs. Nipmuc ancestors in Natick petitioned the state legislature in opposition.
Siegel said removing the dam would carry significance beyond ecology.
"The dams had a lot of negative impacts on Indigenous communities," Siegel said. "When removing the Watertown Dam, which bars herring from traveling, it would be a really significant indicator of how we were working to restore relationships with those Indigenous populations."
Deetz framed it as fulfilling an obligation.
"To be able to see these dams removed, it's for Native people us fulfilling our obligation as caretakers," he said. "To be able to advocate for those things that those neighbors of ours, our relatives need."
Whose History Gets Preserved?
Some have argued for preserving dams as historic structures. Deetz challenges that framing.
"You're looking at people who want to preserve the past of 250 years and trample over the 12,000 years of history of Native people," Deetz said. "It's a blink of an eye in the time we've been here."
He noted the double standard in how history is treated.
"There's no similar outcry when it's the places that are significant to Native people that are being changed and forgotten and altered and built upon and developed," he said.
For Deetz, the question is simple.
"Everything has history. Is that history something that we want to hold on to? The history of damming up the river and blocking the flow of the water?" he said. "Or do we want to say that that's something that we did and we're able to move past?"
The Slow Grind of Public Process
Recognition of the problem isn't lacking.
In June 2021, the Massachusetts Division of Ecological Restoration released a feasibility study confirming removal was possible and beneficial. Estimated cost: $2-3 million. The study identified contaminated sediments behind the dam that would require management.
In December 2022, Watertown City Council wrote a letter supporting removal.
Then the process slowed.
City officials say the municipality is not driving the decision. In a statement, the city said staff are monitoring ongoing conversations about potential restoration or removal of the dam and are proceeding in accordance with guidance from the Massachusetts Department of Conservation and Recreation.
DCR contracted an engineering consultant in 2024 to conduct a separate alternatives analysis. That triggered three rounds of community meetings: July 2024, September 2024, November 2025. At each meeting, comment periods were extended. The study was originally expected to be complete by spring 2025.
Once a decision is made, the project faces a lengthy permitting process.
"Dam removal requires a lot of permits — at least five, sometimes seven or more," Bresney said. "It's a bit of a dance because you don't know how much the project is going to cost until you put it out to bid and ask contractors to put in bids for construction. But you can't do that until you have your permits."
Kumpf said technical barriers aren't the problem.
"One of the challenges that we've really experienced is a lack of willingness to prioritize removal of this dam," Kumpf said. "DCR is a huge agency that covers the whole state, and they do oversee and own a lot of dams, and some are higher hazard potential and in poor condition than Watertown Dam. So that has been a challenge in terms of priorities."
She added, "We've found through a feasibility study in 2021, and now an alternatives analysis that's being wrapped up by DCR, that there's not actually any significant technical challenges to removing the dam. It's more a political challenge."
Susie Bresney, a project manager in the Division of Ecological Restoration's dam removal program, said DCR has not officially decided to remove the dam — but the direction seems clear.
"The most recent study that they completed really only looked at dam removal," Bresney said, "but they haven't officially said, 'Yes, we're going to remove this dam.' That would be the biggest milestone that we're all sort of waiting for."
What Removal Would Look Like
Three alternatives are under consideration:
- Option 1: Partial breach and lowering of the dam to a non-jurisdictional level.
- Option 2: Full dam removal, including river restoration.
- Option 3: Keeping the dam as-is, with continued inspections and maintenance.
Whichever option is taken, if the dam comes down, the river would change.
"When a dam is removed, basically that pool of water that it forms behind the dam, called the impoundment, would reduce in size," Kumpf said. "The banks, especially close to where the spillway is, would become more contained. They would shrink the width of the river channel at that location."
The slow, reflective pool would become a running river.
"It would be more running most of the time and would look more like a natural river," Kumpf said. "For a little bit of time, there would be some exposure of those banks. Through some sediment analysis, engineers have seen that it's actually pretty coarse riverbed material where there would be exposure — some cobbles and boulders and gravel at some locations, and other locations along the banks are more wetland, marshy."
Based on other dam removals, vegetation would grow back within a few years.
"There would definitely need to be care given to managing potential invasive plants that can come in to those exposed banks," Kumpf said. "But we would expect that to grow in nicely over a few years."
Bresney said the changes would bring a rare opportunity for an urban area.
"By lowering the artificial depths of the water to a more natural depth, we gain wetlands along the sides of the river," Bresney said. "That's a huge advantage, especially in an urban environment where we can't make wetlands anymore. There's no space. So this is a really unique opportunity to gain more floodplain in a really urbanized area."
Siegel added that the restored banks would help manage flooding naturally.
"When the banks of the river are restored, it can absorb that water more naturally and help us manage it," Siegel said.
A Precedent for the State
Kumpf said removing Watertown Dam would matter beyond this single site.
"Removing Watertown Dam would really show — it would be a precedent to removing dams not just for hazardous reasons, but for promoting biodiversity and ecological restoration," Kumpf said. "That is not currently being prioritized by a lot of dam owners throughout the state, both state-owned and municipal and private."
She pointed to the Healey-Driscoll administration's biodiversity plan, which set specific goals for preserving and enhancing biodiversity statewide.
"Which is really at the forefront of adapting ecosystems to climate change," Kumpf said, "and not just responding to climate disaster issues for people."
A chance for change
Bresney said community support for removing the dam has been unusually strong.
"There really aren't many voices saying, 'No way, don't remove the dam,'" Bresney said. "And that's actually unique. Pretty much every other project that I have worked on that is really visible and in the center of a town, there are at least some people saying, 'We absolutely have to keep this dam.'"
Removing Watertown Dam would restore fish passage on the Charles River for the first time in nearly 400 years. It would acknowledge the rights of Indigenous communities who depended on the river. And it would show Massachusetts is willing to act before disaster strikes.
One dam will be removed from the Charles River main stem this year, in 2026. Whether Watertown Dam follows depends on whether the state treats ecological restoration as a priority — or waits for the next storm to decide.
Additional reporting on the Clark Sawmill Dam collapse from Vermont Public Radio.