Madam Brett Dam in Beacon, New York. Luwa Elena Yin

The hard work of removing obsolete dams from Hudson River tributaries.

By Luwa Elena Yin

George Jackman often goes into the hills in the Hudson Valley to walk on the trails that stretch along the slopes. Some are particularly rough, covered with tree branches sticking out from every possible direction; some are so steep that a person can barely stand on them. 

Most of the time, Jackman is looking at dams. Some have been there for years before Jackman noticed their existence. Some form waterfalls and reservoirs that have become attractions to the local community. Tourists take photos of them. Weddings take place right above them. 

But Jackman is not there for a relaxing tour. He looks at the dams with a sense of melancholy and frustration. He believes that fish swimming upstream, unable to reach their spawning grounds because of the dams, feel the same way.

Jackman grew up fishing and hunting on the south shore of Long Island. Nature was a respite from a chaotic home life. “I grew up in a very dysfunctional family,” Jackman said. “The only stability in my life was nature.”

At the age of 20, he joined the New York City Police Department. He stayed there for two decades, rising to the rank of lieutenant. He said that he patrolled some “rough neighborhoods” in Brooklyn and that his experience taught him a lot about talking to people in the communities where they lived. Toward the end of his career with the NYPD, while some of his colleagues were pursuing educational opportunities in criminal justice, Jackman began a college degree in biology at Queens College; he graduated with a bachelor’s degree and an award for the highest grade point average. Soon after, he was offered a scholarship at City University of New York Graduate Center for his master’s and Ph.D. degrees; he graduated with a doctorate in ecology, evolution, and behavior.

Now, Jackman works as a habitat restoration manager at Riverkeeper, a local nonprofit and advocacy group for the Hudson River. His major project there is to remove dams from the river’s tributaries. The dams block the flow and function of a river, he said, and “it’s a violation of those rivers’ rights.” The dams themselves, Jackman said, are mostly “obsolete remnants from the Industrial Revolution”; they are “ghosts of capitalism past.” They were built a century ago for many reasons—water supply, mill powering, or even aesthetics. The original owners are long gone, and now the dams are either privately owned by someone from the same family line or have become public properties. A number of them are unpossessed and even unidentified. They could be as short as five feet and as tall as 45 feet. 

Jackman focuses primarily on dams that are considered priority barriers to migratory fish. He conducts planning, outreach, fundraising, and communications to advocate for fish passage and dam removal.

Dam removal is a collaborative effort, from the beginning to the end. It’s never a one-person job. Mostly, Riverkeeper is the general contractor for dam removal projects. Having ensured that the permits are obtained, Jackman is always there when a project is taking place, he said. After a dam is removed, he and his colleagues at Riverkeeper restore and stabilize the landscape by planting trees, for example, which is sometimes turned into a joint effort with college students, local nonprofits, and landscape architects from the local municipality.

Jackman sometimes maps the dams. If he sees one that’s not listed in the dam inventory, he will call the dam safety officials at the New York State Department of Conservation. But most “ghost dams,” as they’re called, do not rise to a level of high hazard, he said. He keeps a database for them, however, just in case. 

The river’s herrings, shads, and eels, for example, are in danger. A 2020 report published by Riverkeeper shows that as many as 16 fish species in the Hudson River are declining, one reason being the dams. The organization launched the Saving Hudson River Fish Campaign in response to the dire conditions. One of many efforts was Riverkeeper’s 2016 dam removal project at Wynants Kill, which was a collaboration with the City of Troy and the New York State Department of Environmental Conservation. Within a few days of the removal, thousands of river herring were coming back to the creek for the first time in 85 years.         

Every season that fish are kept from their natural homes is a season during which fish populations are depleted. And the dams pose other kinds of threats, as well. Having existed for more than a century, many dams are on the edge of breaching, or already breached. Depending on the size of the impoundment behind the dams, the water would possibly flow naturally, or it might flood the nearby landscape once the dam fails. “They are either going to come out in a controlled fashion or a giant kinetic burst,” Jackman said. “So, we either start dealing with them, or they will deal with us.”

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Dams were built thousands of years ago in human history. People built them for traditional reasons—such as water supply, irrigation, flood control, and transportation. 

But during the Industrial Revolution, people started to exploit rivers for their power. While industries such as iron mining and cement manufacturing were expanding, mill dams began appearing almost everywhere powering water wheels.

The number of dams built in the United States during the 18th century was 21, according to the Army Corps of Engineers. It jumped to 2,526 in the 19th century and then more than 10,000 in the mid-20th century. As the political scientist William R. Lowry wrote in Dam Politics: Restoring America’s Rivers, “By the late twentieth century, most American rivers were substantially different from what they had been prior to human intervention.”

In the second half of the 20th century, as part of the growing environmental movement, attitudes toward dams began to change. People began to consider removing dams that were no longer serving their purposes. Not only were dams harming rivers, but they were also becoming dangerous. A 1999 report found that more than 400 dams failed in the United States from 1985 to 1994. In the same year as that report, the Edwards Dam on the Kennebec River in Maine was removed. The project is credited with helping start the dam removal movement. In the Kennebec River, the population of alewives, a migratory fish species, changed from zero to five million within 20 years of the removal. In 2012, two hydropower dams on the Elwha River were removed in Washington State. The project was the largest one in U.S. history. Species such as shad, salmon, and steelhead started to come back to the river.

American Rivers, a national non-profit institution, has kept a database of dam removal projects in the country since 1912. Updated in February 2023, the database documents 2,002 projects. 

But there is still a long way to go. As of now, there are still officially 91,757 dams in the country and 1,915 in New York, with 97% listed as High Hazard Potential Dams. High Hazard Potential is a classification for dams whose failure or misoperation will cause loss of human life and significant property destruction, according to the U.S. Department of Homeland Security. 

In New York, one of the most recent dam removal projects was on Furnace Brook, a tributary of the Hudson, in Westchester County. The project was led by Riverkeeper. Built about 100 years ago, the five-foot-high, 75-foot-long mill dam was removed in November 2020. It was known as Furnace Brook Barrier #1, the first barrier that migratory fish encountered. It also set an invisible line between brackish and freshwater. Both are important to the fish. The dam was drilled by an excavator and taken down within a day. It was not a huge dam, but fish would look at it as a huge barrier that they would never be able to pass, Jackman explained. “It’s like tearing down the Berlin Wall,” he said in a video that recorded part of the dam removal.

Lopane feels strongly about seeing and visualizing the texture of the landscape. Thus, this has become a part of her fieldwork for the upcoming project. 

“Rivers and brooks and streams have evolved over a billion years since there’s been water on the planet,” she said. “And when we went in and just plunk some crap in there, we messed it up.”

Lopane was a part of the restoration team with Jackman for the 2020 project on Barrier #1. Much bigger and thus more complex than the previous one, the Maiden Lane Dam project has been in its planning phase for about five years. The removal is slated for this fall.

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On a recent Friday afternoon, I met George Jackman in Beacon, NY, along with his colleagues Maddie Feaster and Matthew Best, all wearing hoodies and caps. We got out of the car after a few minutes of driving from the train station. Before we saw Fishkill Creek, Jackman looked at me and said, “You can already hear the dam.”

I imagined that there was a trail leading to the dam, but a concrete structure that looked like a beam from the foundation of an old factory was the only way to reach it. “Ready to climb?” Jackman asked, hopping on the beam. 

Another structure we encountered was a concrete fence, at about the thigh level, that we had to climb over. Jackman was leading the way and stopped from time to time, making sure that I didn’t fall or break my camera. I had failed to wear a good pair of hiking boots, not realizing we’d have to climb.

George Jackman, habitat restoration manager at Riverkeeper, was standing close to Madam Brett Dam in Beacon, New York. Luwa Elena Yin

Finally, we reached the dam. It was a substantial dam, 16 feet high and 210 feet long, standing athwart Fishkill Creek, a 33-mile tributary of the Hudson River. This dam once powdered gristmill. It was operated by Catheryna Brett, one of the first European settlers in the city. The dam is now privately owned. Jackman has already acquired permission from the owner to remove it.

The water rushed down from the top of the dam, roaring and forming a beautiful waterfall. Although curvy, the stream is still wide as it flows to the Hudson River. The waterfall has a name, “sucker fall,” Jackman said, mainly because of the white sucker fish that are abundant here.

Jackman reached the river before I did. He stood there, feeling the chilly breeze and modeling the crests and troughs of different parts of the water with his palm and fingers. Aside from the concrete beams that lead to the dam, there was also the remnants of a wheel and a water race with a sluice gate that was not in use anymore. This was too many unnatural structures for Jackman, who looked at them with great melancholy. “The creek has been abused,” he said.

It was overcast, and the water was a grayish blue. There was hardly any green coverage along the shore. The wild winter bush, an abandoned mill, and the water were all blended into monotone. As both of us stopped talking for a while, all I could hear was the roar of the water, falling over the dam. I felt a sense of awe. 

But all of a sudden, Jackman became excited, throwing his arms in the air and touching his head. “Oh, my god,” he said twice. 

I had never seen him this cheerful before.

He pointed toward the bottom of the waterfall; there I saw a great blue heron. It had beautiful light gray and azure blue feathers and a long bill; it was standing at the bottom of the waterfall and looking into the water. The heron was at a perfect spot for fishing because instead of swimming upstream, fish normally get stuck at that location because of the waterfall, Jackman told me. The herons are master fishers, and the one we were looking at was probably hunting for herring.

Then, two others came to the water. One came closer to us, standing on a branch and spreading its wings. The gorgeous sky blue, mixed with threads of snow white, popped up. “This is why we are doing this,” Jackman said. “We are doing it for the fish they are eating.” He pulled out his phone, rushing to get photos. “It’s not just for the river. It’s for everything.” There are ospreys, great blue herons, and bald eagles along this river. “You name it,” he said, adding more names to the wildlife list.

After we moved to another spot close to the pond upstream, we saw a bald eagle.

“You are having one hell of a good day,” Feaster, Jackman’s colleague, said to me. This was only her second time seeing a bald eagle since she moved to upstate New York, she said.

As we were walking back to the small parking lot of Madam Brett Park, we walked past the massive old Tioronda hat factory, which opened in 1879. It had been idle for years before being destroyed by a 2017 fire. Beacon was once the capital of the hat-making industry in New York State. Now, the grass has been growing all over, and the remaining structure of the factory is on the edge of collapsing.

“The Mad Hatter, you know where that’s from?” Jackman asked me. “The Mad Hatter in Batman, the old Batman, the real Batman?” The character became mad as a hatter because of mercury poisoning. What that probably meant, Jackman said, was that there’s still mercury in the soil, left from the hat-making industry.

Another type of dam that Jackman took me to that day was a hydropower dam. It was taller than other dams I had seen, and there was an entire electricity-generating facility nearby. The dam was connected to a turbine. If the turbine is uncovered with fish swimming into it, Jackman said, they could be chopped up instantly. 

Hydroelectricity is reusable but not sustainable, Jackman said. The cost of the energy to the life of the river is just too high.

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Dam removal is not without its controversies. Some environmentalists and many power companies continue to believe that hydroelectric dams are a good source of renewable energy. Others are not so sure.

Many hydropower dams, especially those that are already on the list for removal, are not generating that much power, said Geoffrey Goll, president of the consulting firm Princeton Hydro. One of the hydropower dams that the firm worked on recently was only powering 100 houses, he said. “I always make the joke that if somebody says ‘Can we put hydropower on this small dam,’ I say, ‘Sure, you could do that. You make a kiosk, and you put a light bulb, and you say this dam is powering this one light bulb!” he said. “It’s really all it can do. It’s just not enough.”

Gareth Hougham, a dam removal advocate with Hudson Valley Stream Conservancy, said when the area behind a dam is flooded, small plants, tree stumps, and organics in the soil that were originally part of the landscape go underwater. They begin to rot as time goes by and start to give off carbon dioxide and methane. This is another reason not to keep too many hydroelectric dams.

When the stream rushes down through the reservoir, it becomes warmer, Hougham said. The temperature downstream might be 10 degrees higher than the stream is naturally. Many fish like cold water because it can hold more oxygen. Some species, such as trout, are more sensitive and demanding in terms of water temperature. Rainbow trout, for example, cannot survive when the water is above 77 degrees Fahrenheit. Dams “create havoc with the ecology of the streams below,” Hougham said.

A fish encounters a dam. Courtesy of Gareth Hougham, president of the
Hudson Valley Stream Conservancy.

Aside from considering the environmental harms upstream ponds have, engineers also need to consider what would happen after a dam is removed. There is intense labor and cost that go into removing a dam: it can’t be knocked down overnight.

Princeton Hydro was the engineer of the Maiden Lane Dam removal project. Designers from the firm created a plan that dealt with the sediment that was in the pond behind the dam. It is about 20 feet high and holds about 40,000 cubic yards of sediment, said Goll. He often calls rivers and streams the “conveyor belts” of the breakdown of the mountains and hills. As erosion on the landscape continues to happen, everything from the fine clay to the coarse cobbles gets carried away, and depending on the speed of the water and the grade of the area where it flows, some sink to the bottom along the way. 

The sediment is “a reflection of the watershed,” said Goll. The composition of the sediment tends to be different for individual ponds. Engineers and designers need to determine the best way to transport it downstream, whether at a fast speed or a controlled, gradual speed, without affecting the riverbank. When the amount of sediment is excessive, a part of it might be removed beforehand and put elsewhere on the land to stabilize, which will eventually become a part of the landscape. 

The design sheet from the consulting firm Princeton Hydro for Maiden Lane Dam in Cortlandt, New York. Luwa Elena Yin

Goll thinks of dam removal projects as more of a prediction-making process than a design process; he cannot predict with 100% accuracy where the river will go once the dam is removed. Goll showed me the design sheet of the Maiden Lane Dam project. There are two dotted lines drawn along the lines of the actual waterway. Between them are the waterway and the potential area of the floodplain. This is the area where Goll knows the river channel will be, 95% of the time, he said. However, no matter how extensive the investigation is, the actual river channel is rarely the same as predicted because the sediments and the landscape are always gradually changing. “It is a natural system,” he said. “It’s not like we’re building a house, where we know every two-by-four has its own beam and column.” 

Rivers sometimes surprised Goll by going in a slightly different direction than he’d expected, and in those cases, he said, he respected what nature wanted to do without trying to fix the landscape afterward: “You’ll look at it and go, ‘You know what, I didn’t predict that, but it looks pretty darn good.’” 

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Jackman and his colleagues at Riverkeeper often conduct fish surveys before and after a dam is removed. Before Barrier #1 on Furnace Brook was removed, a group of graduate students from State University of New York College of Environmental Science and Forestry took a sampling survey. They found eight species downstream, within 30 meters of the dam, including a high density of eels.

Born in the Sargasso Sea, American eels migrate to the Hudson River and its freshwater tributaries, where they mature. At a certain point in their life circle, they are cued to return to the ocean. Their sex is determined by environmental factors, such as density. Eels living in a high density environment are destined to become males. In order to become females, the flock needs to spread, migrate upstream, and grow large and fertile.

Dams are one of many reasons why American eel populations are in long-term decline. Approximately 90% of the glass eel population is blocked by dams, and eels have lost about one-third of their habitat.

Jamawissa Creek is the original name of Furnace Brook, Jackman told me. It means “a place of small beavers” in Algonquin. But the detailed history of the brook was fragmented and hard to reconstruct. This is the loss of a culture that Jackman might never be able to recover. 

On our tour of Fishkill Creek, Jackman showed me a third dam. It was in a picturesque spot, and on the other side of the creek, a wedding was taking place. The wedding photographer was taking photos of the group with the dam as a background. Nearby was a catering hall.

This dam was so steep that I could feel the water droplets on my face. It must be extremely hard for fish to pass, and I thought it was one of the projects that Jackman was prioritizing.

But he said it’s extremely hard to propose a removal for a dam that has become a tourist attraction. “Everything about this dam says to me: impossible,” he said. “Because everyone would find it objectionable.” 

Jackman, however, intended to work on it. He would continue educating people, advocating for the fish, and trying, one by one, to clear New York’s rivers of their dams. It was therefore only impossible, in his words, “for now.”