As snow melts off from one of the thinnest snowpacks ever recorded in the Western U.S., the implications for the water supply of the Colorado River Basin are beginning to come into alarmingly sharp focus. Critically low inflows into Lake Powell — the reservoir behind the Glen Canyon Dam — are expected to cause critically low levels as early as August 2026. The water line in Lake Powell currently sits at an elevation of 3,526 feet. If the lake level drops below 3,490 feet — termed the minimum power pool — the turbines that generate electricity have to be shut down. When the water level reaches critically low thresholds, “air is sucked down like a whirlpool into the penstocks, forming explosive bubbles which can cause massive failure inside the dam,” wrote Wade Graham, a writer and historian, in a piece for High Country News.
With the turbines closed, water could be diverted through four eight-foot wide pipes called river outlet works (ROWs). However, these pipes are also subject to damage from cavitation at critically low levels, and Graham wrote that cavitation damage was observed by the Bureau of Reclamation in 2023 when the pipes were used during the April High Flow Experiment. Between the turbines and the river outflow works, there is no way to prevent significant, potentially catastrophic damage to Glen Canyon Dam if water levels drop below 3,490 feet.
The most recent elevation projections released by the Bureau of Reclamation indicates the minimum power pool could be reached by December 2026 in the most probable scenario, and as early as August 2026 if minimum inflow conditions persist. The Colorado Basin River Forecast Center’s April 1 estimate for Lake Powell was 39% lower than the March 1 forecast, and now puts the chance of record low water supply into Lake Powell at more than 30%. With the potential failure of the Glen Canyon Dam becoming more likely, why isn’t the Bureau of Reclamation shutting the gates to preserve the level of Lake Powell until more inflows help the water level recover? In short, the 40 million people who live in the Colorado River Basin need the water.
Seven U.S. states and two Mexican states all share water from the Colorado River. A complicated network of laws and treaties form what is known as The Law of the River. In essence, each state is guaranteed a certain amount of water, but has been allowed to use far more than that, as long as downstream obligations are still met. However, these levels are not tied at all to the current hydrology of the Colorado River Basin. As drought continues to plague the Colorado River Basin, states have relied more and more on draining Lake Powell and Lake Mead, the reservoir behind the Hoover Dam, to get their water. Climate change is bringing less snow on average each winter, meaning that even in good years, reservoirs cannot refill.
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Negotiations over the future of the Colorado River and its storage systems have remained deadlocked for two years, while lake levels continue to drop. The Upper Basin States, Colorado, Wyoming, Utah, and New Mexico, have fundamental disagreements with the Lower Basin States, California, Nevada, and Arizona, over who should have to bear the brunt of water shortages. As November 11 and February 14 deadlines came and went, the possibility of a deal imposed by the Federal Government grew, but perhaps not as quickly as the likelihood that any agreement will wind up in court.
Whether or not states can come up with an agreement on the operation of the Colorado River and its reservoir systems, Lake Powell continues to drop towards the critical minimum power pool. The Bureau of Reclamation has discussed the possibility of releasing huge amounts of water from the Flaming Gorge Reservoir, located on the Wyoming-Utah border. Releases from the Flaming Gorge Reservoir and other reservoirs in 2021 and 2022 helped prop up Lake Powell the last time it came close to reaching the minimum power pool. Flaming Gorge Reservoir is only at 64% of its normal level, and may not be able to provide many more emergency releases. Amy Haas, Director of the Colorado River Authority of Utah, told the Salt Lake Tribune “you may get two or three or four major releases out of Flaming Gorge before you’ve brought that reservoir down to the mud.”
Emergency releases from other reservoirs may save the Glen Canyon Dam one more time, but the long-term future of the Colorado River Basin, and the 40 million people that live in it, is far from certain. Indecision about how to manage the impacts of climate change, not to mention inaction on preventing further warming, continues to fuel problems of monumental size that grow increasingly intractable with each passing year. Habitual overuse of water resources in the Colorado River Basin has led to unsustainable growth of urban areas and agriculture across the Southwest. As the crisis begins to take hold, next winter’s snowpack could be the most important snowpack of the last century. Let’s hope it’s a deep one.
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