Environmental advocates are warning that recent changes to Colorado River management could seriously harm threatened fish in the Grand Canyon. Federal officials are tweaking the amount of water released from Lake Powell in an effort to keep water flowing normally through hydroelectric generators, but those changes may allow invasive species to pass downstream and hurt native fish that live there.
It all has to do with the humpback chub, a species of fish that lives nowhere else on earth besides the Colorado River system. Named after a fleshy bump behind its head, the beleaguered species has become something of a folk mascot for the Colorado River, even inspiring a grassroots campaign to rename a Colorado baseball team.
In 2021, the species was reclassified from “endangered” to “threatened,” but environmentalists said more work to protect the fish was still needed.
Now, its most important habitat may face new threats.
“There's a significant risk that we're going to lose decades of recovery progress for humpback chub in the Grand Canyon and for the species writ large as a result of decisions that are made this year,” said Taylor McKinnon, Southwest director at the Center for Biological Diversity.
The threats all have to do with invasive species like the smallmouth bass. Those fish, introduced into Lake Powell in 1982, like to live in the warm water near the reservoir’s surface. For years, the surface of the reservoir has been far away from the pipes that allow water to flow through Glen Canyon Dam and into the Colorado River on the other side.
But today, the surface of Lake Powell is dropping.
The nation’s second-largest reservoir is caught in the middle of a messy imbalance. Climate change is fueling a 26-year megadrought, putting less water into the Colorado River. Humans are under pressure to reduce their water use across the cities and farms of the Southwest, but state policymakers have been at a monthslong standstill in negotiations about how to do that.
As a result, Lake Powell has dropped to record lows in recent years, and was on track to drop to new historic nadir later this summer before the federal government announced plans to prop it up. The plans would keep the warm water near the reservoir’s surface right near the intakes that allow water, and invasive fish, to pass into the Grand Canyon.
Once there, McKinnon said the invasive fish could “wipe out” the world’s last large source population of humpback chub. He said the new plans — and broader Colorado River management in recent years — are not doing enough to consider wildlife.
“As the states have fought and failed to come up with an agreement about how much water each state gets, the Colorado River’s ecosystems and endangered species have really fallen by the wayside.”
Curiously, the same federal plans that are endangering fish in the Grand Canyon are providing a rare boost for native fish in a different part of the Colorado River system, further north.
Part of the plan to boost water levels at Lake Powell includes adding water from upstream. Massive releases from Flaming Gorge Reservoir, which straddles Utah-Wyoming border, could mimic the natural springtime flows that can help river-based wildlife. Similar releases in 2022 provided a huge boost to populations of razorback sucker, an endangered native species, according to the environmental nonprofit Western Resource Advocates.
