Lake Powell is edging closer to a critical threshold that some experts say could lead to higher electricity costs across parts of the West.
Recent data shows water levels just 34 feet above minimum power pool—the elevation at which Glen Canyon Dam can no longer produce hydropower.
A spokesperson for the U.S. Bureau of Reclamation (USBR), which manages the reservoirs, told Newsweek earlier this month that its recent projections “show Lake Powell could reach minimum power pool in March 2027, but it’s important to note that these projections assume a continuation of the current guidelines, which expire at the end of this year.”
The larger picture also extends beyond Lake Powell’s shores. The drought-stricken Colorado River along which it is situated provides municipal water for about 40 million people, produces more than 8 billion kilowatt-hours of hydropower each year, enough to power roughly 700,000 homes, and sustains 5.5 million acres of farmland.
According to USBR, Glen Canyon Dam, the nation's second-highest concrete arch dam after Hoover Dam, created Lake Powell, which can store 25.16 million acre-feet of water and serves as a drought reserve for cities, industry and agriculture across the West. Its hydropower is distributed to Wyoming, Utah, Colorado, New Mexico, Arizona, Nevada and Nebraska.
What Happens if Glen Canyon Dam Loses Hydropower Generation?
Power generation starts to decline long before Lake Powell reaches its critical level—as water levels fall, reduced pressure through the turbines makes the dam progressively less efficient at generating electricity, professor of civil, construction and environmental engineering at the University of Alabama Hamid Moradkhani told Newsweek.
If the reservoir falls below the minimum power pool level, the dam can no longer generate hydropower. Water releases downstream would continue, but they would be routed through river outlet works instead of the turbines, a system with lower capacity that can pose additional operational and maintenance challenges if relied on for long periods, the expert explained.
The question then becomes how utilities would replace that lost power.
“Utilities would most likely replace the lost hydropower through a combination of wholesale-market purchases, electricity imported from other regions, and increased generation from natural-gas plants,” Moradkhani said. “The basic economic problem is that relatively low-cost hydropower would be replaced by electricity whose price can be higher and more volatile.”
“Customers may not see an immediate, one-to-one increase in their bills. However, higher replacement-power costs would likely be reflected in rates over time, especially for utilities that depend heavily on federal hydropower,” Moradkhani added.
Dwindling water supplies reducing hydropower and contributing to higher power costs or electric bills “is a recurring pattern rather than a one-time event,” according to Moradkhani.
He added: “Our nationwide study found that drought reduced U.S. hydropower generation by approximately 300 million megawatt-hours between 2003 and 2020 and produced an estimated $28 billion in losses to the hydropower sector. About half of those losses occurred in the western United States.”
Vincent Tidwell, a chief scientist at Pacific Northwest National Laboratory, told Newsweek that drought impacts hydropower generation somewhere in the Western U.S. “almost every year."
“Hydropower losses depend strongly on the scale being considered. At an individual facility or in a specific basin, drought impacts can be substantial. For example, Edward Hyatt at Lake Oroville in California had to be shut down with no power produced for several months in 2021 due to reservoir levels dropping too low,” he explained.
Tidwell noted that Oroville was an “extreme case.” Across the broader fleet of hydropower plants in California and Oregon's Southern Cascades, drought has a less significant effect. During an extreme period, hydropower output can fall by about half compared with typical conditions, as occurred during 2012-2015. At the level of the Western Interconnection, the reduction is smaller, with extreme years resulting in roughly 20 percent less hydroelectric generation than average, Tidwell said.
“That’s because drought rarely affects all regions of the West simultaneously. When one area experiences a decline, other plants can ramp up and send power to that area to partially compensate for any loss,” Tidwell added.
The Tradeoff Between Lake Powell and Lake Mead
Then there's the ripple effect on Lake Mead, the nation's largest reservoir. Water released from Lake Powell eventually flows into Lake Mead, but federal water managers said earlier this year they would take steps to bolster water levels at Glen Canyon Dam amid concerns about hydropower generation, including reducing downstream releases. They acknowledged the move could further diminish Hoover Dam's hydropower output.
Moradkhani said: “Holding more water in Lake Powell can help protect Glen Canyon Dam and keep it above critical operating levels. But the same decision means less water reaches Lake Mead, adding pressure to Hoover Dam and its hydropower production.
“The key message is that protecting Glen Canyon Dam by holding more water in Lake Powell can shift some of the hydropower risk downstream to Lake Mead and Hoover Dam. This is not simply a Lake Powell issue; it is a systemwide Colorado River water-and-energy tradeoff.”
Meanwhile, Tidwell said that low storage levels in Lake Mead, and limited flows from Lake Powell are likely to limit power generation at Lake Mead, though he said it should be noted that Powell and Mead together account for just around 5.5 percent of the normal hydropower generation across the Western Electricity Interconnect.
He explained: “While drought may reduce hydropower generation along the Colorado River, hydropower is one part of a larger, integrated electric grid. Grid planners and operators use a range of resources, planning processes, and operational tools to maintain reliable electricity service.
“The issue is not only how much hydropower is generated over a year, but also when that generation is available and what other grid services hydropower can still provide. During drought, hydropower may still support grid reliability, but its role can change depending on water availability, operating constraints, and regional grid conditions. Broader drought impacts include increased electricity prices, directly impacting large industrial and commercial users while most households will not see this price increase impact if they are in regulated markets or did not opt for real-time pricing.”
USBR previously told Newsweek that the Colorado River Basin has been grappling with the lowest snowpack on record. “The basin’s poor hydrologic outlook underscores the need for new operating guidelines for the Colorado River system,” they said.
“The [Interior] Department and Reclamation remain committed to reducing the collective risk of both Lake Powell and Lake Mead falling below critical elevations to protect critical infrastructure so that it can continue to function as authorized to meet the water and hydropower needs of the basin,” the USBR added.
Contact Newsweek editors on this story: James Rushton and Cristina Diciu.