Colorado River managers are proposing a plan to protect Grand Canyon fish, but some say it’s not enough

Colorado River managers are proposing a plan to protect Grand Canyon fish, but some say it’s not enough

Federal water managers have proposed a new plan to protect the Grand Canyon’s native fish species, but conservation groups say it’s not enough.

Water levels in Lake Powell, the nation’s second-largest reservoir, have fallen to historic lows as the region struggles to rein in demand in response to drought conditions fueled by climate change. These lower water levels have allowed non-native fish to pass through Glen Canyon Dam, which holds back Lake Powell, and eat native fish that live on the other side, in the portion of the Colorado River that runs through the Grand Canyon.

The native species in question is the humpback, which is found nowhere on Earth except the Colorado River and its tributaries. It was previously considered “endangered,” but was downgraded to “endangered” in 2021. The fish continues to receive protection under the Endangered Species Act.

Lake Powell, which began filling in the 1960s, was stocked with non-native fish such as smallmouth bass for recreational fishing in 1982. Smallmouth bass prefer warm water near the surface of the reservoir. Now that the reservoir’s surface is lowered, the fish are able to move low enough to enter the pipes inside Glen Canyon Dam that allow water to pass from one side to the other.

The Bureau of Reclamation, the federal agency that manages dams and reservoirs in the West, released a draft plan to release water from the dam in northern Arizona. It proposed five new ways to manage releases from the dam in an effort to keep native fish thriving in the Colorado River below Lake Powell — four of which involve attempts to make the water cooler, disrupting the spawning patterns of non-native fish.

This 2023 chart shows the pipes through which Lake Powell fish can pass into the section of the Colorado River that flows through the Grand Canyon.

US Geological Survey

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Bureau of Reclamation

This 2023 chart shows the pipes through which Lake Powell fish can pass into the section of the Colorado River that flows through the Grand Canyon.

Taylor MacKinnon, Southwest director of the Center for Biological Diversity, objects to two elements of the draft plan. The first is tangible change, he said.

MacKinnon encouraged federal water managers to consider making physical changes to the dam’s intakes themselves — such as adding barriers — to prevent fish from passing through.

“The Bureau of Reclamation has a lot of smart engineers on staff,” he said. “The fact that they haven’t figured out how to do it yet shows that they haven’t made it a priority.”

The second issue described by MacKinnon is more ideological. He said federal water managers are not doing enough to consider the reservoir’s long-term viability in the face of a drought climate.

“Federal agencies need to become proactive,” he said. “They need to look at the science. They need to look at projections for future Colorado River flows in one or two decades. All of this information suggests that Glen Canyon Dam faces inevitable climate deadlock and inevitable obsolescence due to the climate.

Deadpool is the point at which the water in Lake Powell drops too low to pass water through Glen Canyon Dam. A number of conservation groups are encouraging water managers to consider a future in which the dam and reservoir are taken out of use.

The Bureau of Reclamation’s draft plan is now in a 45-day public comment period, which begins on February 9, 2024.

This story is part of ongoing Colorado River coverage, produced by KUNC in Colorado and supported by the Walton Family Foundation. KUNC is solely responsible for its editorial coverage.

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