This winter and spring are shaping up to be bad times for the Colorado River, with a federal forecast predicting flows into Lake Powell at barely three-fourths of normal.
While snowpack has been at or above normal since Jan. 1 in crucial areas of the river’s Upper Basin states of Colorado and Utah, it’s held at well below normal in southern Utah and Colorado and across Arizona.
Snowpack is probably the most crucial element for river flows as the melting snows run off into the river gradually, allowing continuous buildup of spring and summer runoff into the river from the mountains and its tributaries.
Overall precipitation that includes rainfall, however, has been poor above Lake Powell since Jan. 1. It dropped from 96% of normal from October through December 2024 to 69% of normal from Jan. 1-15, federal records show.
The result is that the federal Colorado Basin River Forecast Center is now predicting that April through July flows into Powell will be only 76% of normal. That’s down from 81% at the beginning of 2025.
Flows into Powell are crucial for water supplies in the river’s Lower Basin states of Arizona, California and Nevada because Powell funnels the water directly downstream to Lake Mead, which stores water for this basin.
The low water forecasts, combined with weather forecasts of continued low precipitation through spring 2025, raise the very unlikely but not unthinkable possibility the river could suffer a repeat of the very low flows that plagued it both in 2022-23 and in the early years of the 21st century, two river experts told the Arizona Daily Star.
Low water levels at Wahweap Bay of Lake Powell along the Upper Colorado River Basin are shown in June 2021 at the Utah and Arizona border.
The potential low flows for the next two years represent the very worst case scenario that the federal government predicts today. But if the dry weather persists, and federal forecasts show that happening for at least the next 90 days, both Lake Powell and Lake Mead could be at risk of falling to the critically low levels they reached in 2022 and 2023, said Colorado water researcher and author Eric Kuhn and Jack Schmidt, a longtime Utah State University water researcher.
At that time, federal and state officials were deeply concerned that Powell, for one, would fall below the level at which it can generate electricity for millions of customers in seven states across the river basin. That never happened because in 2023, weather conditions did an abrupt about-face, bringing more spring-summer runoff flowing into Powell than in any year since 2011.
Legal ‘tripwire’
But Schmidt, Kuhn and University of New Mexico researcher John Fleck also warned in a recent blog post that the current low forecasts for river flows and releases downstream from Powell raise the very real possibility that by 2027, releases from the Upper Basin may be low enough to cross what they call a legal “tripwire.”
The “tripwire” would kick in if releases from the Upper to the Lower Basin were to fall beneath a 100-year-old minimum amount set by the 1922 Colorado River compact. It would raise concerns about possible violations by Upper Basin states of the compact and a 1944 water rights treaty between the U.S. and Mexico.
Many although not all legal experts say the Upper Basin states of Colorado, New Mexico, Utah and Wyoming are legally obligated under those agreements to release at least 82.5 million acre-feet of water over 10 years from Lee Ferry. That’s a spot located about 1 mile downstream of the Colorado's confluence with the Paria River, and about 16 miles downstream of Lake Powell.
While Upper Basin states sharply dispute that point, Fleck and company’s latest blog post said as river flows and releases are now forecast and planned, the “tripwire” could be crossed by 2027, a mere two years away.
They based much of their concern on the latest monthly forecast from the U.S. Bureau of Reclamation that Powell would release 7.48 million acre-feet to Mead this year. That’s far below the annual release that’s needed over 10 years to meet the compact obligation.
“The chances of Lee Ferry flows dropping below the 82 million acre-foot tripwire are high. The Colorado River Basin needs to be fully prepared before this occurs,” they wrote.
They were referring to the seven states that are now stalemated over how to fix the longstanding imbalance on the river between water supplies and demand. They need to reach agreement on a system to curb water use by the end of 2026 because the existing system for managing the river expires then, but they’re not close to an agreement now.
“The basin’s litigation clock is getting closer and closer to that midnight hour,” the blog post concluded.
Weather forecasts
A year ago, the river’s short-term outlook was even gloomier than now. The federal Colorado Basin River Forecast Center in late 2023 predicted runoff into Powell would be only 65% to 70% of normal in April-July 2024.
But conditions turned around that winter and spring, with additional snows and rainfall pushing the amount of runoff flowing into Powell for that period to well above 80% of normal.
Right now, however, weather forecasts for this winter and spring in the Colorado River Basin point in the opposite direction.
— For the next 8 to 10 days, the federal Climate Prediction Center forecasts below-normal precipitation for most of Arizona, New Mexico and Southern California and near-normal precipitation in much of Colorado and Utah.
— From now until mid-February, the center forecast projects below-normal precipitation in all of Arizona and New Mexico and most of Colorado.
— Looking 90 days ahead into April, the climate center predicts precipitation will fall below normal in all of Colorado, most of Utah and southern Wyoming, along with all of Arizona, New Mexico and Southern California.
These weak precipitation figures and future forecasts all reflect an ongoing La Niña weather pattern that often brings warmer and drier-than-normal winter weather across the Southwest and Southern Rockies. La Niña weather conditions are generally believed by most scientists to be triggered by below-normal sea surface temperatures in the Pacific Ocean.
The river forecast center predicts La Niña conditions will persist from February through April while starting to transition into more neutral conditions favoring neither high nor low precipitation totals in March.
The reservoirs’ levels
Schmidt, of Utah State University, noted in an email to the Star that today, Lakes Powell and Mead contain a total of 17.3 million acre-feet of water. That’s enough to deliver well over 15 years worth of river water into the Central Arizona Project canal serving Tucson and Phoenix.
The lakes haven’t had that much water since July 8, 2021, he noted. An extreme dry period caused them to plunge by nearly one-fourth, to 13.7 million acre-feet by May 2022 and 12.7 million by March 2023. Heavy rains and snows and significant water conservation across the Lower Basin then allowed the reservoirs to rise back.
But today, “it is completely reasonable that if similar years of dry inflows were to occur again in 2025 and 2026, the basin would be forced to implement severe cutbacks in use. It happened before,” Schmidt said.
Eric Kuhn, a former general manager for a northwest Colorado water district, added that the Bureau of Reclamation’s most pessimistic forecast, which looks two years ahead, sees Powell’s water level falling by November 2026 to barely above 3,509 feet. That’s less than 20 feet above its minimum elevation for generating electricity.
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Mead’s most pessimistic forecast puts it at about 1,030 feet by November 2026. That’s five feet above the level at which the most severe cuts in river water deliveries would be made to the Lower Basin states, including Arizona under existing agreements to save river water. That level is also about 33 feet lower than where Mead stood at the end of 2024.
Those most pessimistic projects are far worse, to be sure, than the “most probable” outlook for November 2026 for those reservoirs. That forecast puts Powell nearly 70 feet higher than the most pessimistic forecast and predicts Mead will be well over 30 feet higher, Reclamation figures show.
But the pessimistic forecasts indicate that even with all the conservation and good-to-excellent precipitation in the past two years, the river isn’t out of short-term danger, Kuhn acknowledged.
“I would not call this ridiculously unlikely,” he said of those forecasts. “It’s not a certainty that we’re headed into another deep multi-year drought, but chances are high enough that we need to be fully prepared for one.”
