A report released Wednesday suggests declining flows on the Colorado River are not only putting power generation at the Glen Canyon Dam at risk, but impacting the ability to deliver water to Nevada, California, Arizona and Mexico, otherwise known as the lower basin.

Compiled by the Utah Rivers Council, the Glen Canyon Institute and the Great Basin Water Network, the report asks Congress to fund major repairs to the dam, which the groups say would be unable to effectively pump water should the reservoir drop below 3,490 feet.

At 3,490 feet, the dam’s ability to generate power for over 5 million people will be kneecapped, falling below the hydropower penstocks that funnel water to the turbines.

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But it will also force the Bureau of Reclamation to pump water through the river outlet works, which the report warns are outdated and could severely limit deliveries to the lower basin, where nearly 30 million people rely on the Colorado River.

“The hydropower penstocks are not only generating hydropower, they’re also the primary mechanism with which the upper basin meets its water delivery obligations to the lower basin states and Mexico,” said Zach Frankel, executive director of the Utah Rivers Council.

The report comes just weeks after the Bureau of Reclamation issued the most extreme water cuts to date — states in the basin need to conserve an additional 2 million to 4 million acre-feet of water, which is roughly one-third of the Colorado River’s annual flow.

Coincidentally, the report released Wednesday points to a 2 million to 4 million acre-foot deficit if the dam’s infrastructure isn’t updated.

If water drops to 3,450 feet, the dam can pump 9.09 million acre-feet annually, still able to deliver the roughly 7.5 million acre-feet apportioned to the lower basin.

But if levels continue to fall, there won’t be enough pressure to pump water through the outlets.

“Because of the reducing water pressure as water levels drop, there simply is not enough water above the river outlet works to push 7.5 million acre-feet through the system,” Frankel said.

According to an analysis from Utah State University, if the level falls to 3,440 feet, the dam can pump 8.28 million acre-feet annually — at 3,430 feet, it can pump 7.41 million acre-feet, which would be a violation of the Colorado River Compact.

If it falls to 3,400 feet, the Bureau of Reclamation can only deliver a meager 3.47 million acre-feet to the lower basin each year, which is almost how much water southern California alone is allotted. And at 3,370 feet, the reservoir would reach deadpool, meaning no water would pass through the dam. The only water in the river at that point would be from tributaries and runoff below Lake Powell.

“If you don’t get enough water through Lake Powell, that’s a massive bottleneck,” said Nick Halberg, research and policy analyst for the Utah Rivers Council.

The outcome would be catastrophic, likely sparking legal battles between states, damaging ecosystems, causing widespread economic harm and straining an already tense water situation in northern Mexico.

The Bureau of Reclamation’s own outlook suggests Lake Powell could fall just below 3,500 feet in March 2023. And according to an analysis from the Utah Rivers Council, in the coming years the reservoir could see those once unthinkable levels, where the dam would no longer generate power or even approach deadpool.

“We don’t have a magic crystal ball, we can’t tell better than anybody else what the next five winters are going to hold for the Colorado River Basin,” Halberg said. “... What we can do, however, is look at periods in the past.”

Using past trends as a model — specifically dramatic four-year declines from 2000 to 2004, and a less dramatic period from 2017 to 2021 — levels could sink below the hydropower tunnels between December 2023 and December 2026.

And by December 2024 to June 2027, the models suggest levels could drop to a point where the upper basin is unable to deliver the allotted water to the lower basin, violating the Colorado River Compact.

A worst-case scenario would be deadpool by June 2025.

“This river is declining so rapidly that our infrastructure is not ready for it,” said Erik Balken, executive director of the Glen Canyon Institute. “And so there’s a real urgency to start studying alternatives to manage this reservoir at these extremely low levels.”

When the desert runs dry

The report suggests two solutions — one would be to modify the river outlet works, whether that means widening the existing tubes, or drilling more.

A second option would be to construct new bypass tunnels for the Glen Canyon Dam, which would give the system “full flexibility,” Balken said.

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“Glen Canyon Dam could be operated all the way down to a natural river level, if the bureau decided to do that,” he said.

Exactly how much those renovations would cost is unclear — a study alone could cost around $2 million, which the Bureau of Reclamation has expressed interest in. And adjusting for 2022 dollars, the original bypass tunnels cost about $84 million.

“We don’t really know how much it’s going to cost,” said Kyle Roerink with the Great Basin Water Network. “But I think in this time of crisis, we would be wise to cross our T’s and dot our I’s. I can’t imagine Congress neglecting this.”

A spokesperson for the Bureau of Reclamation says the agency is preparing a statement in response to the report.

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