Trout and Chub Concerns Grow on the Colorado River


DENVER (TBEN) — To accompany a year or two of fishing trips, Terry took Gunn to the red canyons of northern Arizona. The chance to hike, raft and fly-fish attracted Wendy Hanvold, a retired ski bum, who took a job there at the waiting tables at a fishing lodge. She heard rumors of the intrepid fishing guide who had just returned from a trip to Alaska, and one day, as he entered, he approached his table to take his order.

“You fly fish, don’t you?” she said. “I’ve always wanted to learn it.”

It was a match made in Marble Canyon.

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

But it could all change soon, as warmer water temperatures threaten the survival of fish and the Gunn’s livelihoods.

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

“We’re in totally uncharted territory,” said Gunn, who started touring Marble Canyon in 1983. That year, the Glen Canyon Dam began emergency water discharges after record melting snow caused a powerful runoff in the spring, resulting in the near-failure of the Dam. In all these years the river has been mostly cold, with typical summer temperatures in the 50’s.

But since late August, the water temperature at Lees Ferry – site of a world-famous trout fishery – has risen above 70 degrees seven times. That may be idyllic for a summer swim under Arizona’s blazing summer sun, Gunn said, but nears danger to the beloved sportfish. A few degrees higher can be deadly.

ALSO READ  For chewy Japanese noodles, borrow an Italian technique

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

As the reservoir descends, it sends warmer water with less oxygen to the river below the dam. If that water reaches 73 degrees, Gunn said his family’s guide service could cancel the afternoon trips.

Recently, a small reprieve from cooler temperatures has allayed fears at Lees Ferry, but uncertainty is still in the air.

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

Seven states, Mexico and tribes depend on the stressed Colorado River. They have undergone voluntary and mandatory budget cuts and are grappling with how to further reduce their dependence on the river by about 15 to 30 percent, according to a recent interior ministry mandate.

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

Just a few miles north of Lees Ferry and its trout fishery, there’s another threat: non-native predatory smallmouth bass. They would be in Lake Powell. But this summer they were found in the river below the dam. Smallmouth bass has already wreaked havoc on native fish upstream, where the government spends millions of dollars each year to keep the predators in check. They were kept at bay in Lake Powell because Glen Canyon Dam has served as a barrier to them for years — until now. The recent sharp drop in the reservoir allows these introduced fish to blast through the dam and get closer to the Grand Canyon, where the largest groups of humpback roach, an ancient, endangered, native fish remain.

ALSO READ  Latest Hurricane Ian Updates: Storm Brings Heavy Rain, Winds To South Florida

The National Park Service will even go so far as to apply chemicals to kill these predatory fish on Saturday. The contaminated area is closed off from the river with a vinyl barrier, the desired fish are moved to the main channel, and the substance is applied only to that area, said National Park Service fisheries biologist Jeff Arnold. A second treatment is likely later this fall. 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 longer-term solutions, such as barriers that would prevent fish from even approaching the dam.

A medium-term solution could be a technique that allows cold water to flow from deeper in the lake into the river below. While this would mean foregoing hydropower, the cool water would disrupt the spawning of predatory fish. It has been successful in other rivers and can help protect native fish as well as rainbow trout.

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

Last month, the state of Nevada and the Bureau of Reclamation announced they were investing nearly $12 million in a project to draw water from deeper in the lake to the hatchery. The new line will draw water from a third straw that the Southern Nevada Water Authority has built after a severe drop in water 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.

ALSO READ  Spielberg's 'The Fabelmans' is a juicy ode to the magic of cinema

Walking into a quiet hatchery, normally bustling with running water and air compressors, is a challenge, said the Nevada Department of Wildlife overseeing fish biologist Brandon Singer.

“At first you feel a little 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 as they await their return to fish farming.

Preserving native fish populations is a legal obligation the agency has under the Endangered Species Act. It can sue if it fails to meet that obligation, even if it juggles other urgent demands on the river.

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

Wendy Gunn says that if the trout fishery is lost and smallmouth bass takes over, she can envision Lees Ferry transitioning to a warmwater fishing haven. It would be tragic in many ways, with the much-loved rainbow trout gone and the chance that native fish downstream could be next, she said, but people would still come to cast lines.

“Everyone will just have to adapt,” Wendy said. “You play with it and change or you leave.”

The The Bharat Express News receives support from the Walton Family Foundation for its coverage of water and environmental policies. The TBEN is solely responsible for all content. For all of TBEN’s environmental reporting, visit