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On the Colorado River, growing concern for trout and chub – Morning Journal

By Brittany Peterson

DENVER, AP — Guiding fishing trips for a year or two is what brought Terry Gunn to the red canyons of northern Arizona. The chance to hike, raft and fly fish attracted retired skier Wendy Hanvold, who worked there serving tables at a fishing lodge. She heard rumors about the intrepid fishing guide who had just returned from a trip to Alaska, and one day as he walked in he approached her table to take her order.

“You steal fish, right? ” she says. “I always wanted to learn.”

It was a match made in Marble Canyon.

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

But that could soon all change as warmer water temperatures threaten fish survival and the Gunns’ livelihoods.

The Colorado River’s main reservoirs, Lake Powell and Lake Mead, are both only about a quarter full. The continued decline, due to overexploitation and an increasingly arid climate, threatens fish and the economies built around them.

“We’re in totally uncharted territory,” said Gunn, who started guiding at Marble Canyon in 1983. That year, Glen Canyon Dam began releasing water in an emergency after the melting record snowfall produced powerful spring runoff, causing the dam to nearly fail. In all these years the river has generally been cold, with typical summer temperatures in the 50s.

But since late August the water temperature at Lees Ferry – the site of a world famous trout fishery – has exceeded 70 degrees seven times. It might be idyllic for a summer swim in the scorching Arizona summer sun, Gunn said, but it’s approaching peril for the beloved sport fish. A few degrees higher can be deadly.

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

As the reservoir drops, it sends warmer water with less oxygen into the river below the dam. If that water reaches 73 degrees, Gunn said his family’s guiding service might start canceling afternoon trips.

Recently, a small respite from cooler temperatures has eased the fear in Lees Ferry, but uncertainty continues to cloud the air.

“Mother Nature holds a handful of trump cards 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 stressed Colorado River. They have suffered voluntary and compulsory cuts and are wondering how to further reduce their dependence on the river by around 15-30%, according to a recent mandate from the Ministry of the Interior.

Struggling aquatic life further complicates the already delicate management of rivers and increases the cost.

A few miles north of Lees Ferry and its trout fishery, there is another threat: the non-native predatory smallmouth bass. They are supposed to be contained in Lake Powell. But this summer they were found in the river below the dam. Smallmouth bass have already wreaked havoc on native fish upstream where the government spends millions of dollars every year to control predators. They were kept at bay in Lake Powell because the Glen Canyon Dam served as their barrier for years – until now. The reservoir’s recent steep decline allows these introduced fish to cross the dam and approach the Grand Canyon, where the largest groups of humpback chub, an endangered ancient native fish, remain.

The National Park Service is going so far as to apply chemicals on Saturday to kill these predatory fish. The infested area is isolated from the river with a vinyl barrier, desirable fish are moved to the main channel, and the substance is applied only in that area, said National Park Service fisheries biologist Jeff Arnold. A second treatment is likely later this fall. The Bureau of Reclamation said it would pay $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 even fish from approaching the dam.

A medium-term solution could involve a technique that allows cold water from the depths of the lake to flow into the river below. Although that would mean giving up hydroelectricity, the cool water would disrupt the spawning of predatory fish. It has been successful in other rivers and could help protect both native fish and rainbow trout.

Several hundred miles downstream, at the site of another threat to fish, a hatchery has completely closed. Lake Mead Fish Hatchery, which once raised endangered razorback suckers and chub, ceased operations earlier this year when the lake plunged below where the hatchery drew its water.

Last month, the State of Nevada and the Bureau of Reclamation announced they were pouring nearly $12 million into a project to draw water from deeper in the lake at the hatchery. The new pipe will draw water from a third straw that the Southern Nevada Water Authority built following a sharp drop in lake levels in the early 2000s. As Lake Mead collapsed this year the agency had to start using it to save Las Vegas, and soon, the Hatchery.

Getting into a quiet hatchery, normally buzzing with water and air compressors, is a challenge, said Brandon Singer, a fish biologist supervising the Nevada Department of Wildlife.

“At first you feel a bit lost, your goal is gone,” Singer said. But it was an opportunity for repair work and for his team to work on species in other parts of the state while they waited for them to return to fish farming.

Maintaining native fish populations is a legal obligation the office has under the Endangered Species Act. He could face a lawsuit if he does not respect this obligation, even if he juggles other pressing demands on the river.

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 going to happen.”

Wendy Gunn says if trout fishing is lost and smallmouth bass take over, she could imagine Lees Ferry becoming a haven for warm-water fish. It would be tragic in many ways, with the disappearance of beloved rainbow trout and the likelihood that native fish downstream would be next, she said, but people would still come and cast lines. .

“Everyone is going to have to adapt,” Wendy said. “Either you roll with it and switch or go.”

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The Associated Press is supported by the Walton Family Foundation for coverage of water and environmental policy. The AP is solely responsible for all content. For all of AP’s environmental coverage, visit https://apnews.com/hub/climate-and-environment