DENVER (AP) — That’s what brought Terry Gunn to the red canyons of northern Arizona to lead fishing trips for a year or two. The opportunity for hiking, rafting and fly-fishing attracted Wendy Hanvold, a retired skier who took a job waiting tables at the Fisherman’s Lodge there. She had heard rumors of a fearless fishing guide who had just returned from a trip to Alaska, and one day when he came in she went to his desk to take his order.
“You’re a flycatcher, aren’t you?” she said. “I always wanted to learn.”
It was a match made in Marble Canyon.
Since then, the couple opened a fishing shop, guide services, bought a house, raised a son. They pride themselves on showing tourists the best places to catch and release the prized rainbow trout beneath the rocky cliffs carved by the Colorado River.
But things could soon change, as higher water temperatures threaten fish survival and Anna’s livelihood.
Key Colorado River reservoirs Lake Powell and Lake Mead are only about a quarter full. Continued declines from overexploitation and an increasingly arid climate threaten the fish and the economy built around it.
“We’re in completely uncharted territory,” said Gunn, who started guiding Marble Canyon in 1983. That year, Glen Canyon Dam began an emergency release after record snowmelt triggered powerful spring runoff that caused the water to nearly fail. the dam During all these years, the river was generally cold, with typical summer temperatures in the 50s.
But since the end of August, the water temperature in Lees Ferry – the site of a world-famous trout fishery – has risen above 70 degrees seven times. That may be idyllic for a summer swim under the blazing Arizona summer sun, Gunn said, but it’s approaching danger for the beloved sport fish. A few degrees higher can be fatal.
To make matters worse, as temperatures rise, the amount of dissolved oxygen in the water drops, making it difficult for fish to even breathe.
When the reservoir is lowered, it sends warmer water with less oxygen into the river below the dam. If the water reaches 73 degrees, Gunn said his family’s guide service may start canceling trips after lunch.
Recently, a slight reprieve due to cooler temperatures has eased the fears at Lees Ferry, but uncertainty is still in the air.
“Mother Nature has a few trump cards, and if she decides to play one of them, there’s nothing you can do about it,” Gunn said.
Seven states, Mexico and tribal nations depend on the busy Colorado River. They experienced voluntary and mandatory cuts and are grappling with how to further reduce their dependence on the river by about 15-30 percent, for the last mandate Department of Internal Affairs.
The struggle of aquatic life further complicates the already delicate management of the river and increases the cost.
Just a few miles north of Lees Ferry and its trout fishery, there is another threat, the non-native predatory perch. They are believed to be held in Lake Powell. But this summer they are were found in the river below the dam. Smallmouth bass have already wreaked havoc on local fish upstream, where the government spends millions of dollars each year to control the predators. They were kept at bay in Lake Powell because the Glen Canyon Dam acted as a barrier to them for years – until now. The recent dramatic drawdown of the reservoir allows these introduced fish to push through the dam and approach the Grand Canyon, where the largest populations of humpback, an ancient and endangered native fish, remain.
The National Park Service goes so far as to use chemicals on Saturdays to kill these predatory fish. The infested area is sealed off from the river with a vinyl barrier, the desired fish are moved into the main channel and the substance is applied specifically to that area, said National Park Service fisheries biologist Jeff Arnold. A second treatment will likely take place later this fall. The Bureau of Reclamation said it will contribute $30,000 for the second treatment and is exploring additional funding from the Bipartisan Infrastructure Act and the Inflation Reduction Act for long-term solutions, such as barriers that will keep fish from even approaching the dam.
A medium-term solution may involve engineering that allows cold water from the depths of the lake to flow into the river below. Although this would mean giving up hydropower, the cooler water would prevent predatory fish from spawning. This has been successful in other rivers and can help protect both native fish and rainbow trout.
A few hundred miles downstream, in another threat to the fish, one hatchery came to a complete halt. The Lake Mead fish hatchery, which used to breed endangered walleye and walleye, shut down earlier this year when the lake dropped below the point where the hatchery took water.
Last month, the state of Nevada and the Bureau of Reclamation announced they would invest nearly $12 million in a project to draw water from deep in the lake to the hatchery. The new line will receive water from a the third drop which the Southern Nevada Water Authority built after a severe drop in lake levels in the early 2000s. When Lake Mead plummeted this year, the agency had to start using it to save Las Vegas, and soon the hatchery.
Entering the silent hatchery, which is usually bustling with running water and air compressors, is a challenge, said biologist Brandon Singer, who oversees the Nevada Department of Wildlife.
“At first you feel kind of lost, your purpose is gone,” Singer said. But it was an opportunity to make repairs and for his team to work on species in other parts of the state while they await their return to fish farming.
Maintaining native fish populations is a legal obligation of the bureau under the Endangered Species Act. He could face legal action if he defaults on that commitment, even as he juggles other pressing demands on the river.
Back upstream near Lake Powell, introduced rainbow trout do not have the same protection. Losing them would be heartbreaking but seems inevitable, said Terry Gunn, who religiously checks the water temperature. “It’s like watching a family member grow old or die — it’s bound to happen.”
Wendy Gunn says if the trout fishery is lost and smallmouth bass take over, she can imagine Fox Ferry moving into a warm water haven. She said it would be tragic in many ways with the beloved rainbow trout gone and the possibility that local fish in the lower reaches could be next, but people would still come to cast their lines.
“Everybody’s going to have to adapt,” Wendy said. “You either change or you leave.”
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