For generations, the Hudson River has been both a natural artery of the Northeast and a mirror of the region’s environmental choices. Once written off as an industrial sewer, the river has seen remarkable recovery since the height of its pollution in the mid-20th century. But the work is far from finished. Climate change, habitat stress, and invasive species now test the resilience of an ecosystem that, by some measures, has improved dramatically—and by others, remains in a precarious balance.
“I would give it about a B rating,” says Dr. Stuart Findlay, an aquatic ecologist at the Cary Institute of Ecosystem Studies in Millbrook who has spent more than three decades studying the river. “On the plus side, water quality is hugely improved from what it was 30, 40 years ago. But some of the fishes are not doing so well, and that brings the score down.”
Findlay will speak at the Hudson River Maritime Museum on September 24 from 7-8:30pm on “Hudson River Ecology: How is the Hudson River Doing & How Do We Know?”
From Sewage to Clean Water
Findlay’s “B” assessment begins with water quality. In the 1970s, stretches of the Hudson were plagued by raw sewage, industrial effluent, and oil slicks. Combined sewer overflows routinely discharged untreated waste during heavy rains, leaving water unsafe for swimming or fishing. Federal legislation—the Clean Water Act of 1972—spurred investment in wastewater treatment plants, while state and local efforts tightened enforcement and upgraded systems.
“Wastewater management is the single biggest driver of improvement,” Findlay explains. “Those combined sewer overflows, at least in this part of the river, don’t happen much anymore. That’s gotten a whole lot better. So that kicks the score up.”
Educators and students collect data along the Hudson River as part of the Hudson River Environmental Conditions Observing System (HRECOS) network, which provides continuous water quality monitoring and helps scientists track long-term ecological change.
The impact is clear in monitoring data. HRECOS, a network of sensors deployed along the estuary, tracks salinity, oxygen, pH, and turbidity in real time. Dissolved oxygen, once chronically low in many reaches, now remains within healthy ranges. “Low oxygen was a real problem,” Findlay says. “It basically doesn’t happen anymore. And we can say that with confidence because we’ve got sensors that tell us even at night when no one’s out measuring.”
In recent months, a new tool has made that vigilance more accessible to everyone. Riverkeeper, with funding secured by Senator Chuck Schumer, has launched a Water Quality Portal that provides real-time and historical data on water quality along the Hudson River watershed. The interactive map lets residents explore when and where it’s safe to swim or boat, whether fish are safe to eat, the cleanliness of drinking water, and even local pollution sources. For scientists like Dr. Findlay, such transparency is a welcome reinforcement to systems like HRECOS. The new portal helps extend that confidence to communities—what happens upstream or downstream can now be tracked by anyone with internet access.
Fish in Flux
If water chemistry is a success story, fish populations reveal a more uneven picture. American shad, once so abundant that their spring runs fed entire river communities, have declined to a fraction of historic levels. Atlantic sturgeon, another keystone species, were driven close to collapse by overfishing.
“Shad are still not doing well,” Findlay cautions. “They’re trying to make a comeback, but it would be unfair to say it’s happened yet. Sturgeon look as though they’re making a comeback. They’re not in free fall anymore, but they have a long way to go to get back to what many people would call acceptable levels.”
The biology of sturgeon complicates recovery. Females may not reproduce until age 30, meaning population rebounds span human generations. Shad, meanwhile, continue to face disputed levels of harvest pressure even as habitat restoration projects attempt to ease their migration.
Vital Habitats
Beyond fish, two habitats dominate Findlay’s concern: submerged aquatic vegetation and tidal wetlands. Both provide critical nursery grounds for fish and invertebrates, stabilize sediments, and filter pollutants.
After Hurricane Irene in 2011, submerged vegetation was “essentially wiped out completely,” Findlay recalls. Yet it has rebounded to roughly 80 percent of prior coverage. “This year looks quite good,” he notes, though he cautions that what counts as “the best we’ve seen” may not represent a permanent baseline.
Tidal wetlands—like Constitution Marsh across from West Point—are in better shape, bolstered by regulatory protections that curb dredging and development. Roughly 200 tidal wetlands line the estuary, some large enough to be named, many small and unnamed. Their survival, however, hinges on whether they can keep pace with sea level rise. “As best we can tell, some will and some won’t,” Findlay says. “So the useful thing is, for those that won’t, what can we do about it, if anything?”
Climate as the Defining Force
When asked to weigh human shoreline impacts against climate change, Findlay reframes the question. “Climate change is human-driven,” he points out. “It’s got to be the biggest thing—how fast water’s coming in, how long it stays dry, what the temperature cycles are like.”
The stakes are sobering. Projections indicate the Hudson River will rise by about one meter—more than three feet—by the end of the century. Already, sea level at the Battery in Lower Manhattan has climbed more than a foot since 1900. Along the mid-Hudson, train stations such as Peekskill routinely flood during high tides and storms. “The parking lot floods regularly now,” Findlay says. “The train tracks aren’t much higher.”
Future adaptation will involve both engineering and retreat. Rail lines and riverfront roads will need to be raised. Wastewater plants and fuel depots may need relocation. “There’s going to be some retreat and just let the river have part of the shore back,” Findlay predicts. The good news, he adds, is that these changes are gradual enough to be folded into infrastructure planning. “That kind of thinking is now pretty widespread,” he says. “It was not true 20 years ago.”
Trade-offs and Contradictions
Findlay emphasizes that environmental decision-making often involves difficult trade-offs. He points to the recently installed Champlain Hudson Power Express, a buried transmission line in the river bringing Canadian hydropower to New York City. Its construction disrupted river sediments, and scientists worry the line’s magnetic field could affect fish that rely on electromagnetic cues for migration.
“There’s a downside to this power line,” Findlay acknowledges. “But there’s an upside too: that hydropower is less polluting than certainly burning coal and even probably burning natural gas. So there’s an upside from a human point of view and a downside from an ecological point of view.”
Reconciling such contradictions requires transparency and public participation. “Rather than just saying, ‘Nope, let’s do this,’ which frankly got us into some of these messes in the past, the goal is to lay out the pluses and minuses,” Findlay says. “Here’s what we know, here’s what we don’t know, and how do we balance them?”
Eyes on the River
For Findlay, the Hudson’s greatest defense may be the number of organizations monitoring it. From Riverkeeper to Clearwater to Scenic Hudson to the state Department of Environmental Conservation, a web of advocates and regulators scrutinizes every major proposal. “It would be really hard for some major change to be imposed under cloak and dagger,” he says. “People are going to know, and they’ll have a chance to say something.”
That vigilance, however, does not guarantee action. Findlay expresses frustration at the lack of progress on invasive species entering via the New York State Canal System. Despite decades of warnings, political will has lagged. “It’s pathetic,” he says bluntly. “We know what’s happened, we know what could happen, and there’s just no movement to do something serious about it.”
Citizens’ Role
Asked how ordinary people can support the river, Findlay is unequivocal: pay attention. “The natural resources of the state belong to the people,” he says. “Clean air, the Hudson River, vistas—they belong to the people of New York. So pay attention to how your stuff is being looked after.” That can mean following local press, signing up for newsletters, or attending public meetings. “You can’t say, ‘I didn’t know how to find out.’ Information acquisition these days is easy.”
A Cautious Optimism
Despite looming threats, Findlay resists fatalism. “I’m an optimistic person,” he says. “We do know a lot about what’s going on, plus and minus, and there are a lot of people with the best interest of the resource at heart. That doesn’t mean there won’t be problems, because there will. But we’re going to do our best when they crop up, and we’ll do our best to get out in front of them.”
For a river that has endured centuries of exploitation, that optimism reflects both hard-won progress and ongoing vigilance. The Hudson may not be pristine, but neither is it the lost cause some once declared. Its grade, for now, is a B—solid, but with plenty of room for extra credit.
Tickets to Findlay’s lecture at the Hudson River Maritime Museum on September 24 from 7-8:30pm are $10, $5 for museum members.
A Brief History of the Hudson’s Recovery
By the mid-20th century, the Hudson River was in crisis. Decades of unchecked industrial discharge, municipal sewage, and oil spills had left large stretches of the estuary unsafe for recreation or fishing. General Electric alone dumped an estimated 1.3 million pounds of PCBs into the upper Hudson between 1947 and 1977, contaminating sediments and prompting a decades-long federal Superfund cleanup.
The tide began to turn with the passage of the federal Clean Water Act in 1972, which required states and municipalities to modernize wastewater treatment and curtail raw sewage discharges. Local victories soon followed. Grassroots advocacy groups like Scenic Hudson and Clearwater—Pete Seeger’s sloop-based nonprofit launched in 1966—raised public awareness, sued polluters, and lobbied for stronger enforcement. Seeger often called the river “an open sewer,” but he believed citizens could reclaim it with persistence and song. His Clearwater festival became both a fundraiser and rallying point for a generation of river activists.
Over the ensuing decades, billions were invested in wastewater infrastructure. The Hudson River Estuary Program, created in 1987, coordinated scientific research and restoration efforts. By the 1990s, swimming and boating had returned to reaches once deemed off-limits. Today, PCBs remain a challenge in the upper river, but water quality in much of the estuary is dramatically improved.
That progress, however, is only partial. As Dr. Stuart Findlay notes, “Wastewater improvements took 20 or 30 years to put in place.” The next chapter—adapting to sea level rise and climate disruption—may prove just as demanding.
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Jules Conway