Every fall, a crane trundles in and, three times a day, hoists a massive steel hopper from beneath the swirling pools of the Winooski River Salmon Hole.
The cargo: fish. Atlantic salmon are heaved into pickup trucks by the dozens and deposited as far as 20 miles away into the greater Lake Champlain basin as part of the effort, which has existed since 1993.
In the past few years, scientists have seen record numbers of the species lifted from the Salmon Hole. In 2023, the latest data available, teams pulled out 212 salmon — the highest number in 30 years.
The largest tributary to Lake Champlain, the Winooski River snakes 90 miles from Cabot in the east, connecting to seven brooks and streams on the way. Those waters are home to some of the highest-population salmon runs in Vermont, and scientists say the fish are a reliable measure of the lake’s and basin’s ecological health.
So, the salmon's success is a good sign — and an endorsement of water quality efforts.
But those close to the efforts say accelerated climate change and federal budget cuts pose a threat to future progress.
“Atlantic salmon are native to Lake Champlain, and it’s part of our role to maintain those native populations,” said Lee Simard, a leading Salmon Hole researcher from the Vermont Department of Fish and Wildlife. “And if the salmon are doing well, then that’s a good indication of the overall health of the Lake Champlain ecosystem.”
Fish and Wildlife is cracking down on sea lampreys, an invasive parasitic fish, as part of its efforts to bolster salmon numbers.
Also called “vampire fish,” lamprey have no natural predators in the basin — allowing them to use rows of razor teeth to bore holes into salmon unchecked, siphoning fluids and nutrients to sustain themselves and leaving the salmon to bleed out en masse.
Researchers have constructed low-head dams — concrete structures hidden just beneath the water — to ensnare adult lamprey, isolate them and use chemical lampricides to exterminate them and their larvae.
Measures were implemented in 2023 and have yielded positive results since then, Simard said.
“We’ve had record-low wounding rates,” he said. “As a result, more salmon are surviving and being able to come back to the river to spawn, and so we’ve been seeing stronger returns in recent years.”
Another area of improvement for the salmon has been with invasive plant removal.
Species like buckthorn, honeysuckle and bittersweet outcompete native river plants for sunlight and soil nutrients, said Tim Larned, superintendent of the Winooski Valley Park District, the main stewardship org for the Salmon Hole. The lack of native plants means less food for insects like mayflies and caddisflies — a vital food source for Atlantic salmon.
These plants damage the river’s water quality, too. The group’s initiatives help stabilize that food cycle and inform locals about the river’s conservation.
“At the Salmon Hole, we had a large group from Burlington High School help us out,” Larned said. “We spent the day clearing a couple of areas down there, and a high school group can get really motivated and get into pulling out good-sized stumps.”
The Friends of the Winooski River nonprofit replaces those stumps with anywhere from 1,500 to 3,000 native tree saplings every year, according to its website.
Native forests are usually best positioned to live along rivers and purify the water by absorbing runoff and expunging excess nutrients like nitrogen and phosphorus.
“Having natural areas up to the edge of the water helps improve the habitat,” Larned said. “Anything that we can do on the shoreline can help … fish down in the river.”
Increased flooding threatens to undo those efforts in a single moment — endangering salmons’ migratory routes and livelihood.
Last July, the Winooski River and the Salmon Hole flooded for miles. The high-velocity torrents clawed through the riverbanks, ripping trees from the ground and eroding the soil. The erosion makes it difficult for remaining trees to stay rooted and prevents new trees from growing at all.
Michele Braun, executive director of the Friends of the Winooski River, explained that the sudden decrease in trees allowed swaths of sediment to seep into the river unimpeded.
Unprecedented amounts of phosphorus latched onto that sediment and sank to the bottom of the river. Algal blooms produced by that phosphorus imbibe oxygen and clog salmons’ gills, causing them to asphyxiate.
“Cyanobacteria and algae blooms are driven by phosphorus coming from the river,” Braun said. “We need to reduce the phosphorus content contribution in the river by about a third, and we need projects to improve the general health of the sediment transport system of the river, and that should improve water quality and reduce phosphorus to Lake Champlain.”
In addition to phosphorus, PFAS — or polyfluoroalkyl substances, dubbed “forever chemicals” — are also infiltrating the salmons’ home.
Last year, an activist group sounded the alarm when manufacturer GlobalFoundries dumped PFAS-ridden effluent into the Winooski River. Subsequent research from the state Department of Environmental Conservation found PFAS levels at 26.36 parts per trillion — gravely higher than the state’s 20 parts per trillion safeline.
Salmon that breathe PFAS-contaminated water suffer from toxic buildup in their skin tissue. Marine biologists are finding that the toxicity can sterilize salmon and lead to ferroptosis — a form of cell death that can cause virus buildup.
“PFAS are a big problem, but we don’t have much information about it,” Braun said. “The testing for PFAS is super expensive. My husband, a water quality scientist, is doing a study on PFAS and says it costs nearly $7,000 to collect one sample. We just wish we had more answers.”
The Friends of the Winooski River coordinates one of Vermont’s largest water quality monitoring efforts. The group works with over 30 organizations to conduct annual studies to get some of those answers, Braun said.
But the Trump administration’s budget cut spree is jeopardizing the studies’ longevity, Braun said.
Slashed funding has halted the Friends of the Winooski River’s ongoing projects, she said.
“We’re very concerned about long-term funding,” Braun said. “Half of our funding was frozen in February and projects were significantly set back. We’ve had great support from Vermont Fish and Wildlife, but we’re worried about their funding too. With all of the federal disinvestment in climate change and resilience, we’re going to be in a difficult position in the future. It’s daunting.”
The president has also proposed that the U.S. Fish and Wildlife Ecological Services Program, a close ally of Vermont Fish and Wildlife, lose $37 million of its budget.
Despite an uncertain future, other success stories in Lake Champlain are a silver lining. Simard said it took 50 years of hatchery stocking and intervention for lake trout populations to stabilize in the basin.
Simard said it might not be possible to achieve similar outcomes with Atlantic salmon because of dam usage and changing regulations for fisheries management, but he, his fellow researchers and volunteer groups want to do their best to get there.
As Braun put it: “We’re on the right track, but we need to keep it up.”
The Community News Service is a program in which University of Vermont students work with professional editors to provide content for local news outlets at no cost.
