More than 30,000 small dams currently block river tributaries from Maine to Maryland. New initiatives to remove them are aimed at restoring
Although dam removals have been happening since 1912, the vast majority have occurred since the mid-2010s, and they have picked up steam since the 2021 Bipartisan Infrastructure Law, which provided funding for such projects. To date, 806 Northeastern dams have come down, with hundreds more in the pipeline. Across the country, 2023 was a watershed year, with a total of 80 dam removals. Says Andrew Fisk, Northeast regional director of the nonprofit American Rivers, “The increasing intensity and frequency of storm events, and the dramatically reduced sizes of our migratory fish populations, are accelerating our efforts.”
Dam removals in the Northeast don’t generate the same media attention as massive takedowns on West Coast rivers, like the Klamath or the Elwha. That’s because most of these structures are comparatively miniscule, built in the 19th century to form ponds and to power grist, textile, paper, saw, and other types of mills as the region developed into an industrial powerhouse.
But as mills became defunct, their dams remained. They may be small to humans, but to the fish that can’t get past them “they’re just as big as a Klamath River dam,” says Maddie Feaster, habitat restoration project manager for the environmental organization Riverkeeper, based in Ossining, New York. From Maryland and Pennsylvania up to Maine, there are 31,213 inventoried dams, more than 4,000 of which sit within the 13,400-square-mile Hudson River watershed alone. For generations they’ve degraded habitat and altered downstream hydrology and sediment flows, creating warm, stagnant, low-oxygen pools that trigger algal blooms and favor invasive species. The dams inhibit fish passage, too, which is why the biologists at the mouth of the Saw Kill transported their glass eels past the first of three Saw Kill dams after counting them...
Jeremy Dietrich, an aquatic ecologist at the New York State Water Resources Institute, monitors dam sites both pre- and post-removal. Environments upstream of an intact dam, he explains, “are dominated by midges, aquatic worms, small crustaceans, organisms you typically might find in a pond.” In 2017 and 2018 assessments of recent Hudson River dam removals, some of which also included riverbank restorations to further enhance habitat for native species, he found improved water quality and more populous communities of beetles, mayflies, and caddisflies, which are “more sensitive to environmental perturbation, and thus used as bioindicators,” he says. “You have this big polarity of ecological conditions, because the barrier has severed the natural connectivity of the system. [After removal], we generally see streams recover to a point where we didn’t even know there was a dam there.”
Pictured: Quassaick Creek flows freely after the removal of the Strooks Felt Dam, Newburgh, New York.
American Rivers estimates that 85 percent of U.S. dams are unnecessary at best and pose risks to public safety at worst, should they collapse and flood downstream communities. The nonprofit has been involved with roughly 1,000 removals across the country, 38 of them since 2018. This effort was boosted by $800 million from the Bipartisan Infrastructure Law. But states will likely need to contribute more of their own funding should the Trump administration claw back unspent money, and organizations involved in dam removal are now scrambling to assess the potential impact to their work.
Enthusiasm for such projects is on the upswing among some dam owners — whether states, municipalities, or private landholders. Pennsylvania alone has taken out more than 390 dams since 1912 — 107 of them between 2015 and 2023 — none higher than 16 feet high. “Individual property owners [say] I own a dam, and my insurance company is telling me I have a liability,” says Fisk. Dams in disrepair may release toxic sediments that potentially threaten both human health and wildlife, and low-head dams, over which water flows continuously, churn up recirculating currents that trap and drown 50 people a year in the U.S.
Numerous studies show that dam removals improve aquatic fish passage, water quality, watershed resilience, and habitat for organisms up the food chain, from insects to otters and eagles. But removals aren’t straightforward. Federal grants, from the National Oceanic and Atmospheric Administration or the Fish and Wildlife Service, favor projects that benefit federally listed species and many river miles. But even the smallest, simplest projects range in cost from $100,000 to $3 million. To qualify for a grant, be it federal or state, an application “has to score well,” says Scott Cuppett, who leads the watershed team at the New York State Department of Environmental Conservation’s Hudson River Estuary Program, which collaborates with nonprofits like Riverkeeper to connect dam owners to technical assistance and money...
All this can be overwhelming for dam owners, which is why stakeholders hope additional research will help loosen up some of the requirements. In 2020, Yellen released a study in which he simulated the removal of the 1,702 dams in the lower Hudson watershed, attempting to determine how much sediment might be released if they came down. He found that “the vast majority of dams don’t really trap much sediment,” he says. That’s good news, since it means sediment released into the Hudson will neither permanently worsen water quality nor build up in places that would smother or otherwise harm underwater vegetation. And it shows that “you would not need to invest a huge amount of time or effort into a [costly] sediment management plan,” Yellen says. It’s “a day’s worth of excavator work to remove some concrete and rock, instead of months of trucking away sand and fill.” ...
On a sunny winter afternoon, Feaster, of Riverkeeper, stands in thick mud beside Quassaick Creek in Newburgh, New York. The Strooks Felt Dam, the first of seven municipally owned dams on the lower reaches of this 18-mile tributary, was demolished with state money in 2020. The second dam, called Holden, is slated to come down in late 2025. Feaster is showing a visitor the third, the Walsh Road Dam, whose removal has yet to be funded. “This was built into a floodplain,” she says, “and when it rains the dam overflows to flood a housing complex just around a bend in the creek.” ...
On the Quassaick, improvements are evident since the Strooks dam came out. American eel and juvenile blue crabs have already moved in. In fact, fish returns can sometimes be observed within minutes of opening a passageway. Says Schmidt, “We’ve had dammed rivers where you’ve been removing the project and when the last piece comes out a fish immediately storms past it.”
There is palpable impatience among environmentalists and dam owners to get even more removals going in the Northeast. To that end, collaborators are working to streamline the process. The Fish and Wildlife Service, for example, has formed an interagency fish passage task force with other federal agencies, including NOAA and FEMA, that have their own interests in dam removals. American Rivers is working with regional partners to develop priority lists of dams whose removals would provide the greatest environmental and safety benefits and open up the most river miles to the most important species. “We’re not going to remove all dams,” [Note: mostly for reasons dealing with invasive species management, etc.] says Schmidt. “But we can be really thoughtful and impactful with the ones that we do choose to remove.”
-via Yale Environment 360, February 4, 2025
