On the Colorado River, increasing concern for trout and chub

On the Colorado River, increasing concern for trout and chub

Colorado River Fish At Risk (ASSOCIATED PRESS)

Colorado River Fish At Risk (ASSOCIATED PRESS)

To guide fishing trips for a year or two is what brought Terry Gunn to the red canyons of northern Arizona. The chance for hiking, rafting and fly fishing attracted Wendy Hanvold, a retired ski bum, who took a job waiting tables at a fishing lodge. She heard rumors about the intrepid fishing guide who had just returned from a trip in Alaska, and one day when he came in, he approached her table to take his order.

“You flyfish, 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 service, bought a cabin and raised their son. They pride themselves on showing tourists the best places to catch and release prized rainbow trout beneath rugged cliffs carved by the Colorado River.

But that could all soon change as warmer water temperatures threaten the fish’s survival and Gunn’s livelihood.

Key Colorado River reservoirs Lake Powell and Lake Mead are both only about a quarter full. The continued decline, due to overconsumption and an increasingly drier climate, threatens the fish and the economies built around them.

“We’re in totally uncharted territory,” said Gunn, who began guiding in Marble Canyon in 1983. That year, Glen Canyon Dam began releasing water on an emergency basis after record snowmelt produced heavy spring runoff, resulting in the near-failure of the pond. In all these years, the river has usually been cold, with typical summer temperatures in the 50s.

But since the end of August, the water temperature at Lees Ferry – the site of a world-renowned trout fishery – has risen above 70 degrees seven times. It may be idyllic for a summer dip under the scorching Arizona summer sun, Gunn said, but is approaching danger for the beloved sportfish. A few degrees higher can be fatal.

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

When the reservoir falls, it sends warmer water with less oxygen into the river below the dam. Should the water reach 73 degrees, Gunn said the family’s guide service could start canceling afternoon tours.

Recently, a brief reprieve of cooler temperatures has taken the edge off fears at Lees Ferry, but uncertainty still hangs in the air.

“Mother Nature has 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 undergone voluntary and mandatory cuts and are grappling with how to further reduce dependence on the river by about 15 to 30 percent, according to a recent mandate from the Interior Ministry.

Struggling with aquatic life further complicates the already delicate river management and increases costs.

Just a few miles north of Lees Ferry and the trout fishery there is another threat – non-native predatory fish. They should be confined in Lake Powell. But this summer they were found in the river below the dam. Smallmouth bass have already wreaked havoc on native fish far upriver, where the government spends millions of dollars each year to control the predators. They were kept at bay in Lake Powell because Glen Canyon Dam has acted as a barrier to them for years — until now. The reservoir’s recent sharp decline allows these introduced fish to shoot through the dam and edge closer to the Grand Canyon, where the largest groups of humpbacks, an ancient, endangered, native fish, remain.

The National Park Service is going so far as to use chemicals Saturday to kill these predatory fish. The infected area is sealed off from the river with a vinyl barrier, desirable fish are moved to the main channel, and the drug is applied to that particular area, said National Park Service fisheries biologist Jeff Arnold. A new treatment is likely later this autumn. The Bureau of Reclamation has said it will contribute $30,000 for the second treatment, and is exploring additional funding from the Bipartisan Infrastructure Law and Inflation Reduction Act for long-term solutions such as barriers that would prevent fish from approaching the dam.

A medium-term solution may involve a technique that allows cold water from deeper in the lake to flow into the river below. Although this would mean forgoing hydropower, the cool water would interfere with the spawning of predatory fish. It has been successful in other rivers and can help protect both native fish and rainbow trout.

Several hundred miles downstream, at the site of another fishing threat, one hatchery has completely shut down. The Lake Mead Fish Hatchery, which used to breed endangered razorback sucker and bonytail chub, ceased operations earlier this year when the lake dipped below the point where the hatchery drew water.

Last month, the state of Nevada and the Bureau of Reclamation announced they are kicking in nearly $12 million for a project to draw water from deeper in the lake into the hatchery. The new line will draw water from a third straw that the Southern Nevada Water Authority built after a sharp drop in lake levels in the early 2000s. When Lake Mead plunged this year, the agency had to start using it to save Las Vegas, and soon the hatchery.

Walking into a quiet hatchery, normally buzzing with running water and air compressors, is a challenge, said Nevada Department of Wildlife Supervising Fisheries Biologist Brandon Singer.

“At first you feel a little lost, your purpose is gone,” Singer said. But it has been an opportunity for repair work and for his team to work with species in other parts of the state while they wait for them to return to fish farming.

Maintaining native fish stocks is a legal obligation the agency has under the Endangered Species Act. It could face a lawsuit if it fails to meet that obligation, even as it juggles other pressing demands on the river.

Back upstream near Lake Powell, the introduced rainbow trout do not have the same protection. Losing them would be heartbreaking but feels inevitable, said Terry Gunn, who checks the water temperature religiously. “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 the trout take over, she could imagine Lees Ferry turning into a haven for warm water fish. It would be tragic in many ways, with the beloved rainbow trout gone and the likelihood that native fish downstream could be next, she said, but people would still come to cast lines.

“Everybody just has to adjust,” Wendy said. “Either you roll with it and change, or you go away.”

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

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