On a wet day in late August, George Jackman, an aquatic ecologist who works on habitat restoration, stood at the edge of Quassaick Creek in upstate New York.
The Quassaick, which flows through the small town of Newburgh, New York, and empties into the Hudson River, was unusually shallow after a summer with little rain. “It looks bucolic now,” Jackman said. “But it can be a raging torrent.”
For 300 years this torrent had been contained by a small dam that once fed a nearby mill, where the Stroock Felt company made carriage blankets for the horse and carriage trade, then military blankets and woolen uniforms during the first World War. .
Further upstream, other dams once produced electricity to run local candle and iron factories, woolen and paper mills – sites which made Newburgh a bustling industrial town in the 19th and early of the XXth century.
Most of these factories have long since closed, but their dams have remained, creating an ecological problem that Jackman, who quit his job as a New York City police lieutenant in 2005 to pursue a doctorate in ecology, is determined to tackle. solve.
Tributaries like the Quassaick provide critical habitat for fish that swim upstream to spawn, like river herring, striped bass, and Atlantic sturgeon, and for species that do the reverse, like American eel . Dams disrupt their ancient pathways, fragmenting habitat and interfering with the life cycles of these migratory species. Conservationists like Jackman, who works for the environmental group Riverkeeper, want to take them down.
For him, the dams are an ugly reminder of a terrible past. “It was a hellish place,” Jackman says. When the dams powered nearby industries, he says, “there were no environmental laws. There were no child labor laws. There were no unions. There was no Clean Air Act, no Clean Water Act. It was a place of death.
Jackman’s mission is to dismantle these “ghosts of capitalism,” as he calls the abandoned structures, and bring damaged ecosystems back to life.
He is not alone: environmental movements in the United States and Europe have locked their views on the destruction of dams. In the Pacific Northwest, Indigenous leaders led the charge against the Gorge Dam, 100 miles northeast of Seattle. Last year, a record number of dams were removed from European rivers. And in New York State, the demands of activists are also gaining ground. Two years ago, an excavator demolished the Stroock mill dam: a barrier that had blocked the path of migrating fish for centuries disappeared in a week.
Riverkeeper wants to continue and is looking for funds to demolish the barriers above the Stroock dam. “We’re trying to restore habitat to dispossessed organisms in long-term decline,” Jackman said.
It is a matter of urgency, he said, not only because aquatic species are under threat, but because obsolete structures are failing. “If they were to break through in one big kinetic burst, some of them would endanger people’s lives.”
BBefore the dams were built, generations of river herring swam from the Atlantic Ocean to New York Harbor, up the Hudson River and its many tributaries, following their instincts to seek cool stream beds where they could lay their eggs. But for the past three centuries, when the fish reached Quassaick Creek, more than 50 miles from the port, they came to a dead halt, blocked by the Stroock Felt Mill Dam and older dams before that. Their numbers began to steadily decline.
Across America’s 3 million miles of rivers, hundreds of thousands of dams built to power factories in the early industrial age are still in place. In New York State, in the Hudson River estuary, only half of the river’s 67 tributaries flow freely; the others are blocked by no less than 2,000 low dams.
Dams fragment habitat, impeding the flow of sediments and nutrients and degrading river ecosystems upstream and downstream. “With climate change, the waters are getting warmer, so especially for cold-water species, trapping them further downstream can be problematic for their survival rate,” said Serena McClain, director of river restoration for the non-profit group American Rivers.
The dams also pose a risk of flooding: they weren’t built to withstand the stronger storms that came with a warmer planet, and they’re deteriorating. When they collapse, they can flood neighboring communities.
But those barriers are beginning to fall. Since 1998, more than 1,500 dams have been removed across the country, according to American Rivers, including two large hydroelectric dams along the Elwha River in Washington state that endangered wild salmon populations, and many other small dams such as the mill dams on the tributaries of the Hudson.
Some people have opposed plans to remove dams on the grounds that these remnants of American industrial heritage should be preserved. Others use ponds created by dams for boating or swimming; landowners may worry that pond drainage will leave an unsightly mud pit and spoil their view of the waterfront.
“Maybe they have a house, a dock, they fish there,” said Brian Rahm, director of the Water Resources Institute in New York, which works on removing barriers. Rahm is therefore working with landscape architects to sketch out what the waterways will look like when the dams are removed and the banks restored and reseeded. “When they imagine change, they only see things going away; it’s hard to imagine the desirability of what could be put there in its place.
FFurther upstream, Jackman cut his way with a machete through a towering thicket of Japanese knotweed to reach Walsh Mill Dam. The dam no longer feeds the grain and sawmills that once stood nearby and begins to crack, making it a hazard to its neighbors.
Just downstream is the Mullins Courtyard apartment complex, a housing estate for low-income tenants that was built in the creek’s floodplain. The complex was flooded during recent severe storms: after Hurricane Ida last September, the Mullins apartments were flooded and the playground was submerged under several feet of water. If Walsh Dam were to collapse in another hurricane, the flooding could be catastrophic.
To make matters worse, on the edge of the Quassaick is a main sewer – which, if destroyed, could flood the area with human waste.
Such flooding could be financially devastating for residents of Newburgh, where more than twice as many people live below the poverty line as in the county as a whole. Low-income people are less likely to receive housing assistance from the Federal Emergency Management Agency after a natural disaster, and when they do receive funds, they tend to receive less.
Riverkeeper has submitted a proposal to the National Oceanic and Atmospheric Administration to fund further work on the Quassaick, hoping some of the $800 million set aside in last year’s infrastructure bill for the removal of the dam. And in the Hudson Valley, other projects are also planned; by 2030, the State Department‘s Estuarine Program for Environmental Conservation intends to dismantle the dams to reconnect at least 25 miles of streams.
Environmentalists say that when even small and seemingly insignificant structures are demolished, there is a cascading effect on the entire riparian ecosystem. Sediment that once accumulated behind the barriers now flows freely, forming riffles, mudflats and sandbars that harbor various aquatic creatures and create tidal marshes that help protect the shoreline from violent storms.
When the natural flow of a stream is restored, “you get a richer population of insects, and the insects feed the fish, and the fish feed the birds, and the birds provide a wider web of services, and other animals come in,” Rahm says. “You get a more resilient ecosystem all around, and it just trickles down from the flow.”
Evidence suggests that migrating fish find their way to their cold water spawning grounds, even when their routes have been blocked for many generations. A study published in the journal BioScience found that “upstream migration was evident within weeks to months” after the demolition of small dams in the Midwestern and Eastern United States, and “up to 95% of all species found downstream of dams migrated upstream in 1-3 years”.
In some cases the fish move much faster: When a dam was removed from the Wynants Kill near Troy at the upper end of the Hudson River estuary, within days underwater cameras recorded thousands of silver river herring swimming in the newly opened stretch of river.
Before returning to his truck, Jackman stood at the edge of the Quassaick and pointed out where the creek had begun to meander from its old course in the two years since the dam was removed. Now that the dam is gone, “the river is regaining its shape,” he said. “We have to let the water go where it needs to go.”