Oops! 40,000 acre-feet of water slipped through the cracks at Lake Powell

As the drought-strapped Colorado River struggled to feed water into Lake Powell to keep its massive storage system and power turbines from crashing in 2021 and 2022, the U.S. Bureau of Reclamation, its operator, was scrambling to bring in extra water from Flaming Gorge and Blue Mesa reservoirs.

Since the return of healthier flows in 2023, water levels in Flaming Gorge and Blue Mesa have been restored, as required under a 2019 Colorado River Basin drought response plan.

But the subsequent shifting of water in 2023 to balance the contents of lakes Powell and Mead, required under a set of operating guidelines approved in 2007, resulted in an accidental release of 40,000 acre-feet of water that will not be restored to the Upper Basin because it is within the margin of error associated with such balancing releases, according to Alex Pivarnik, supervisory hydrologist with Reclamation’s Upper Colorado Basin Region.


“Under the 2007 Interim Guidelines, this was the first time Reclamation balanced the contents between lakes Powell and Mead in near real-time, working against quickly changing hydrology over the course of just a few months. Getting it within 0.5% is pretty remarkable, given the circumstances,” Pivarnik said via email, referring to the hundreds of thousands of acre-feet of water that was being moved at the time relative to the size of the mistake.

Though 40,000 acre-feet of water isn’t much on the massive Colorado River, it is enough to serve some 80,000 houses for one to two years, to irrigate 20,000 acres of corn on the Eastern Plains or to keep the taps flowing in the Grand Junction-area for two years.

“Some people might wonder what’s the harm,” said Mark Ritterbush, water services manager for Grand Junction. The city is one of three water providers in the Grand Valley, some of whom also rely on the Colorado River. “But does it matter? Absolutely. It is all one water.”

The seven-state Colorado River Basin is divided into an upper and lower section, with the Upper Basin covering Colorado, New Mexico, Utah and Wyoming and the Lower Basin comprising Arizona, California and Nevada.

The Upper Basin is home to four major reservoirs. Flaming Gorge, on the Utah-Wyoming border, Colorado’s Blue Mesa, New Mexico’s Navajo, and Lake Powell. They serve as liquid bank accounts, ensuring the Upper Basin states can meet their legal obligations to deliver water to states in the Lower Basin, where Lake Mead serves a similar function.

A map showing the Colorado RIver's path from Colorado to the Gulf of California in Mexico.

Looking ahead, Upper Basin states say the way the reservoirs are managed during drought emergencies needs to change to protect against such mistakes and to better protect Upper Basin water supplies.

“Reclamation missed its operating target for releases by 40,000 acre-feet. Everyone should recognize that this is a shortcoming of the 2007 guidelines,” said Chuck Cullom, executive director of the Upper Colorado River Commission, which oversees the Colorado River for the Upper Basin states.

“It’s almost impossible to hit perfect. But this is a function of trying to balance contents [of Powell and Mead],” Cullom said.

Despite the drought response and a healthy water year in 2023, lakes Powell and Mead have returned to critical low levels, leaving the system vulnerable in ways similar to those that existed prior to the emergency loans from the Upper Basin states, according to the Colorado Water Conservation Board (CWCB), whose staff presented a memo on the topic at its May meeting. The CWCB is the state’s lead water planning agency.

As the giant river system continues to struggle to serve 40 million people, tribal communities, farmers and Mexico, tense negotiations to redo the 2007 operating guidelines, which expire in 2026, are underway.

“With regard to future reservoir operations in the post-2026 negotiations,” Cullom said, “I would say that the upper division states have learned a great deal from the operation of the [drought response plan], and in the event that the federal government wants to continue to have the flexibility to move the water from upper basin units to protect the operation of Lake Powell. … I would expect those lessons would be reflected [in the new operating guidelines].”

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