Watertown Dam Removal

This post is authored by the Charles River Watershed Association (CRWA). The analysis and opinions in the post are those of the CRWA. Senator Brownsberger shares it for discussion without endorsing the analysis and opinions.

Along the Charles River Greenway, near the bustling Watertown Square and Galen Street Bridge, you will find a site of rushing water over a concrete structure. Many know this site to be the spillway of the Department of Conservation and Recreation (DCR)’s Watertown Dam. Watertown Dam is an aging, 180-ft long, 8-ft high concrete weir structure located in the Charles River in Watertown, MA. Previous dam structures at the site were originally built to power industry of the 1800s and the current dam now serves no purpose, whether it be for power, water supply or flood control. Instead, it is a barrier to a free-flowing Charles River, impeding migratory fish passage, destroying the river ecosystem, and harming climate resilience.

The current dam is a “significant hazard potential” structure in fair condition. If it were to fail during a severe storm, flooding may put downstream areas in Brighton, Newton and Watertown “at risk of loss of life, damage to property and critical infrastructure, and large-scale economic disruption,” according to the Watertown Dam Removal Feasibility Study . Removing the spillway will eliminate any chance of catastrophic dam failure.

This is becoming more significant with stronger storms and increased rainfall occurring more frequently as a result of a changing climate.

The feasibility study also found that if the dam were to be removed, there would be no changes in flooding downstream. Additionally, flood elevations would be reduced by six feet as far as half a mile upstream of the dam.

On the ecological and ethical side, dam removal has the potential to welcome migratory fish populations back to an additional forty miles of the Charles River ecosystem, restoring life to our river and healing historic wrongs. Kristen Wyman from the Natick Nipmuc Indian Council spoke about the significance of the potentially removing the Charles River Dam in Natick as a member of the Town of Natick Charles River Dam Advisory Committee:

“Who would have ever thought, my ancestors, that I’d be speaking here a couple of hundred years later about the potential removal of one of those dams. I am encouraging us to think long-term about the possibility of that fish being revived because we do not give up that hope as Indigenous people, we will never give up that hope. We know that all things are possible.”

– Kristen Wyman, Nipmuc leader and member of Natick Nipmuc Tribal Council, Charles River Dam Advisory Committee Meeting on November 9, 2021.

Every spring, migrating alewife, American eel, American shad, blueback herring and rainbow smelt migrate through the Charles River into Watertown. While some Alewife and blueback herring can pass the fish ladder on the Watertown Dam, many fish cannot pass through. The fish ladder is on the shallower side of the river and very few fish stray from the deep water, where the water is colder. Thus, many fish never even find the ladder and cannot proceed past Watertown.

A study by the Massachusetts Division of Marine Fisheries and the U.S. Fish and Wildlife Service has found that the female American shad are unable to climb the ladder at Watertown Dam. Removing the dam would allow free passage for the fish unable to climb ladders.

Removal would also eliminate the congregation of fish trying to get up the ladder and decrease the subsequent instances of predation and poaching.

Not only is the dam bad for fish passage, it degrades the quality of the water in the Charles River in the impoundment, or ponded, section of the river upstream of the dam.

Because the water is slowed down, water temperatures increase and dissolved oxygen levels decrease – bad for fish and other aquatic wildlife. These conditions can also lead to increases in potentially harmful algae or cyanobacteria outbreaks in the river, which can be a danger to folks on the water and dogs who may go into the water.

Additionally, the benthic, or bottom, habitat in the impoundment stretch of river would improve after dam removal, making it better suited for macroinvertebrate bugs that fish feed on and a better habitat for the fish species to move and thrive.

In June 2021, the Massachusetts Division of Ecological Restoration (DER) released the final draft of the Watertown Dam Removal Feasibility Study. The report confirms removing Watertown Dam is indeed feasible.

The removal of Watertown Dam is supported by, and not limited to, the following organizations: Native Fish Coalition Massachusetts, Sierra Club Massachusetts, Trout Unlimited Greater Boston Chapter.

With the bipartisan infrastructure law in place, federal funding from agencies such as the National Oceanic and Atmospheric Administration (NOAA), U.S. Fish and Wildlife Service, Army Corps of Engineers, US Department of Transportation, and more, are being made available for dam removal and restoration projects like the Watertown Dam. The migratory fish make this project competitive for funding, especially from NOAA.

Speaking of costs, because this dam is owned by DCR, taxpayers are on the hook for ongoing inspection and maintenance of the dam structure. Removal would be a one time cost with all of the environmental benefits and eliminate any ongoing maintenance for a structure which is not currently serving a purpose.

In conclusion, removal of the Watertown Dam offers the opportunity to improve habitat, transform water quality, restore native plants, improve recreational paddling passage, and remediate contaminated sediment, increase climate resilience for future extreme weather events, and protect downstream areas from future flooding.

For more information read CRWA’s story map A River Interrupted and visit CRWA’s Watertown Dam website.

25 replies on “Watertown Dam Removal”

  1. We need to remove these dams. They are no longer useful and cause untold environmental damage. It’s time for us to think about the future, not the past.

  2. The Watertown Dam removal makes ecological sense and is in keeping with dam removals all over the country. Let’s get rid of it, so we can enjoy a freeflowing Charles River.

    1. Thank you for proposing to get rid of the damn and hopefully other human structures that destroy the environment .

  3. Prior to COVID I would go to Watertown frequently. as many bus exchanges at Watertown Sq. As a MA Sierra Club member, I strongly support the removal of the Watertown Dam at Watertown Square, to allow the Charles to flow more freely, help the wildlife especially the migratory fish, increase the water quality and allow the Charles to be Climate Resilient.
    I hope the South Natick spillway is removed as well so there is more continuous Charles flowing naturally.

  4. I, too, am a 50yr. resident in the affected dam removal area and also support this measures for all the stated reasons.

  5. We strongly support the removal of the Watertown Dam for environmental (and fish!), safety, and recreational reasons.

  6. It is high time the town officials remove the Watertown Dam for many ecological sound benefits for the natural ecosystem and humans depending on them! Every action helps to stop the ecocide unfolding everywhere.


  7. So is there a plan to remove the dam?? If not, then who in Watertown is responsible for that??

    1. Hi Jean,
      Some of the arguments against dam removal have been surrounding people like the aesthetics of the spillway that people think is a Waterfall. However this dam was built at the “head of tide” or area where the high tide historically came up to, so this area has a natural change in elevation. Comment below from Marilynne Roach of the Historical Society in Watertown also talks about this. Feasibility study found there is a change in elevation so design of dam removal would and can include features like riffles, rocks so people can hear and see the sound of water flowing over a surface.
      Other concerns some residents have is if the dam removal would have negative impact on wildlife upstream, answer is no, dam removal would have a positive impact, the wildlife have evolved with free flowing river over thousands of years, improved water quality, lower temperatures and dissolved oxygen and connectivity would all be a big benefit.
      If you have any more questions or concerns feel free to reach out to me directly at rkearns@crwa.org.

  8. My main concern about removing the Watertown dam is that I suspect that there is a considerable amount of toxic sludge backed up behind it that is fairly stable in its current undisturbed state at the bottom of the river. This sludge is a legacy of the industrial activity in Waltham and Watertown over the past 200 years or so. Removing the dam will undoubtedly send large quantities of this sludge into the lower Charles River basin where it could cause innumerable problems for both people and animals if it turns out to be toxic. I do not support the removal of the dam until the sediments in the sludge behind it have been thoroughly tested and are determined not to pose a risk to the long-term health of the Charles River.

    1. Hi Peter,
      Great question and concern. This is something that would be addressed in the design, permitting and construction of this or any dam removal. Any sediments that are contaminated would be subject to a sediment management plan.
      The feasibility study did have some amount of sediments that would be removed and remediated off site which is another environmental benefit to this project. Would much rather have these sediments be managed properly. This has been done and is planned to be done in other dam removals successfully in the Housatonic River in Pittsfield and the Monatiquot River in Braintree to name a couple. Feel free to reach out to discuss more my email is rkearns@crwa.org.

  9. There are so many reasons to do this! Thanks for publishing this, Will. Like Jean, I would be interested to hear the arguments against but I am confident that the benefits of removing will overcome any resistance.

  10. I’m not knowledgeable about this subject, so will rely on the experts. It sounds like there are many good reasons to remove the dam. I too am curious if there are any benefits to keeping or altering it, but none have been stated (will the birds that I enjoy watching find other places to feed?). A free-flowing Charles would be nice!

    1. Hi Larry,
      The birds will still feed there, as well as at the other upstream dams and fish ladders where the migratory fish congregate.
      A free-flowing river in Watertown could allow for more passage of Alewife, Blueback Herring, American Shad (who’s females can’t get up the fish ladder), and Rainbow Smelt (who can’t get up the fish ladder). Increased passage and access to spawning habitat means more baby fish and therefore more food for birds and other wildlife.
      If you have any more questions or would like to chat feel free to reach out to me at rkearns@crwa.org

  11. Well past time for the dam to go! I have lived near the Watertown Dam for 5 years now, first in the Nonantum neighborhood of Newton and in Watertown for the last 2+ years. I frequently ride my bike along the river and stop by the dam to see the fish, birds and occasional small brown mammal swimming in the water (possibly river otters.) The Charles River is such a beautiful resource. Let’s get rid of that dam already and let nature restore it’s native resiliency.

  12. I, also, am a Watertown resident, and I have attended two presentations by the CRWA. They have convinced me that the Watertown dam should be removed by experts as soon as feasible. I look forward to that.

  13. Something to think about:
    The drop in water level at this location was originally a natural feature of the landscape well before anyone built anything there.
    The first published reference to the site is in William Wood’s 1634 New-England’s Prospect, where he describes a 1633 visit to Watertown and its “fall of fresh waters, which convey themselves into the Ocean through Charles River.”
    The Charles was tidal until the dam was built at Boston: salt water flowed upstream twice a day as far as this fall.
    Therefore, the original natural state of the river included a fall low enough to allow fish passage over the drop yet high enough to stop an ordinary high tide.

  14. An earlier comment by Dr. del Tredichi raised questions about the possibility that toxic sludge could be released by removal of the dam. I am not an expert on dams, but I am an ecologist and policy analyst, a resident of Watertown, and a contributor to the Town’s Resilience/Climate Plan. So in response to Dr. Tredichi’s concerns, I first looked for a recent and authoritative scientific review of experience with dam removals around the world, paying particular attention to what it had to say about toxics, chemicals, health risks, etc. With that in mind, I carefully read the (long) Watertown Dam Feasibility Study noted in Sen. Brownsberger’s posting. Here is a (short) summary of what I learned:
    The most authoritative general scientific review I found on dam removal is Foley et al. (2017). Dam removal: Listening in. Water Resources Research, 53(7), 5229–5246. https://doi.org/10.1002/2017WR020457. On the subject of toxic chemicals, it concludes that the impoundments behind dams “may contain toxic substances, and the release of contaminants in the accumulated sediment are a major concern for local communities [Wildman and MacBroom, 2005], especially after the calamitous 1973 removal of Fort Edward Dam on the Hudson River released PCB-contaminated sediment [Shuman, 1995]. Because many reservoirs were created decades or centuries ago, neither the original topography nor the composition of accumulated materials may be well known. Evaluation of potential contaminants such as DDT, heavy metals, toxins, and radionuclides is now common, and purposeful dam removals are engineered to prevent or limit their release [e.g., Stanley and Doyle, 2003; Evans and Wilcox, 2014; Evans, 2015].”

    The Watertown Dam Feasibility Study (link in Sen. Brownsberger’s posting) took the risks of toxic sediment release seriously. It tested for a comprehensive range chemicals of concern in the sediments above and below the dam that could be mobilized by dam removal. Chemicals detected at levels above those that scientists have shown to pose a danger to human and ecosystem health include lead, chromium, arsenic, and multiple PAH’s (polycyclic aromatic hydrocarbons). Other chemicals of concern that were detected, but not at levels currently known to threaten health, include PCBs (polychlorinated biphenyls) and chlorinated pesticides. The Study concluded: “Chemical constituents found within the sediment exceed the requirements of Massachusetts Contingency Plan (MCP) guidance and will require additional testing to develop a formal sediment management plan. It is anticipated that up to 1,700 cubic yards (CY) of sediment will need to be removed surrounding the direct upriver vicinity of the dam, and additional sediment pockets found in the former impoundment would be tested, removed, and disposed of off-site, if necessary” (Executive Summary Table 1, pg. ES-i). (Those wishing to explore the exhaustive details behind this conclusion will find it useful to search the full report using terms “sediment,” “chemical,” or “contaminant.” Summary text appears on pp. 13-14, 55, 66, 70, pg. 16 of the appendix “Sediment Sampling Report”).

    I conclude that before I could support an otherwise desirable dam removal (with all the free river, ecological, and flood safety benefits that would entail), I would need to see the additional chemical testing, health risk assessment, and “formal sediment management plan” recommended by the Watertown Dam Feasibility Study. Is such an effort in the works?

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