In the Colorado River, increased concern for trout and walleye

By Brittany Peterson/AP

That’s what brought Terry Gunn to the red canyons of northern Arizona to lead fishing trips for a year or two. The chance to hike, raft and fly fish lured Wendy Hanvold, a retired skier, who took a job waiting tables at a fishing lodge. He had heard rumors of an intrepid fishing guide who had just returned from a trip to Alaska, and one day he approached his desk when he came in to pick up his order.

“You’re a fly fish, aren’t you?” he said. “I’ve always wanted to learn.”

It was a match made in Marble Canyon.

Since then, the couple has opened a fishing shop, a guide service, bought a lodge and raised their son. They pride themselves on showing tourists the best places to catch and release prized rainbow trout beneath the steep cliffs carved by the Colorado River.

But that could all change soon as the temperature of the water heat threatens the survival of the fish and the livelihood of the Gunns.

Key Colorado River reservoirs Lake Powell and Lake Mead are both only about a quarter full. Steady declines due to overexploitation and increasingly arid climates threaten fish and the economies built around them.

“We’re in completely uncharted territory,” said Gunn, who began guiding at Marble Canyon in 1983. That year, Glen Canyon Dam began an emergency release after record snowmelt caused heavy spring runoff, resulting in a near-failure. dam. Throughout the years, the river has typically been cold, with typical summer temperatures in the 50s.

But since the end of August, the water temperature at Lees Ferry, a world-famous trout fishing spot, has risen above 70 degrees seven times. Gunn may be unusual for a summer bath in the blazing Arizona summer sun, but it’s approaching danger for its beloved sport fish. A few degrees higher can be fatal.

To make matters worse, when temperatures rise, the amount of dissolved oxygen in the water decreases, making it difficult for fish to even breathe.

As the reservoir drops, 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 cancel afternoon trips.

Recently, a brief respite from the cold temperatures has eased the fear at Lees Ferry, but uncertainty still taints the air.

“Mother Nature has a few cards up her sleeve, and if she decides to play one, there’s nothing you can do about it,” Gunn said.

Seven states, Mexico, and tribal nations depend on the highlighted Colorado River. They have undergone voluntary and involuntary cuts and are struggling to reduce their trust in the river by about 15 to 30 percent, according to a recent mandate from the Department of the Interior.

Fighting aquatic life makes already delicate river management more difficult and costly.

A few miles north of Lees Ferry and its trout fishery lies another threat – the non-native predatory smallmouth bass. They were supposed to be stored at Lake Powell. But this summer they were found in the river below the dam. Smallmouth bass have already wreaked havoc on the local fishery, where the government spends millions of dollars each year to control the predators. They have been kept in Lake Powell since Glen Canyon Dam has acted as a barrier for them for years – until now. Recent dramatic declines in the reservoir allow these introduced fish to jump the dam and approach the Grand Canyon, where the largest populations of ancient, endangered, native fish remain.

The National Park Service is going so far as to apply chemicals on Saturday to kill these predatory fish. National Park Service fisheries biologist Jeff Arnold said an infected area is sealed off from the river with a vinyl barrier, the desired fish are moved to the main channel and the substance is applied to that area. A second treatment is possible later this fall. The Bureau of Reclamation said it would contribute $30,000 for the second treatment, and is exploring additional funding from the Bipartisan Infrastructure Act and the Inflation Reduction Act for longer-term solutions, such as barriers that would prevent fish from even approaching the dam.

A medium-term solution may involve a technique that allows cold water from deep in the lake to flow into the river below. Although this means giving up hydropower, the cooler water will 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 down the road, in another fish threat, a hatchery was completely shut down. The Lake Mead Fish Hatchery, which used to raise endangered razorbills and bonetail fry, shut down earlier this year when the lake dropped below the hatchery’s withdrawal point.

Last month, the state of Nevada and the Bureau of Reclamation announced they were spending about $12 million on a project to pump water from the lake’s depths into the reservoir. The new line will take water from a third spillway built by the Southern Nevada Water Authority after lake levels dropped dramatically in the early 2000s. As Lake Mead dwindled dramatically this year, the agency had to start using it to save Las Vegas and soon the hatchery.

Brandon Singer, a fish biologist with the Nevada Department of Wildlife, said breaking into a silent hatchery, usually filled with running water and air compressors, is a challenge.

“At first you feel lost, your purpose is gone,” the singer said. But it was an opportunity for renovations and for his team to work on species in other parts of the state while they wait for them to return to fish farming.

Conserving local fish populations is a legal obligation under the bureau’s Endangered Species Act. If he fails to fulfill this obligation, even if he fulfills other current requirements in the river, he can face court.

From near Lake Powell upstream, introduced rainbow trout do not have the same protection. Terry Gunn, who religiously checks the water temperature, says losing them would be heartbreaking but feels inevitable. “It’s like watching a family member grow old or die—it’s going to happen.”

Wendy Gunn says if the trout fishery is lost and smallmouth bass take over, she can imagine Lees Ferry becoming a haven for warm water fish. He said it would be tragic in many ways, with the beloved rainbow trout gone and native fish likely to be in the next stream, but people would still come to cast lines.

“Everyone will have to adapt,” Wendy said. “Either you roll with it and change, or you walk away.”

The Associated Press receives support from the Walton Family Foundation to cover water and environmental politics. AP is responsible for all content.

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