Lake Powell, facing an existential crisis from drought and climate change, is getting a nearly 1 million acre-foot reprieve.

The way has been cleared for the federal government to send a half-million acre-feet of water from an upstream reservoir to Lake Powell. At the same time, the feds will keep nearly 500,000 more acre-feet in Powell instead of letting it flow downstream to Lake Mead.

These actions should prevent Lake Powell from falling so low in the near future that Glen Canyon Dam’s power-generating turbines would have to be shut off.

But many experts agree the fix is only temporary as long as river flows keep declining as they have since 2000. More steps, including additional conservation, will be required to keep the river system sustainable in the long run, authorities said.

The two short-term fixes for Powell announced late last week are:

The seven Colorado River Basin states wrote a letter to U.S. Assistant Interior Secretary Tanya Trujillo, accepting Interior’s April 8 proposal to hold back 480,000 acre-feet of water from the ailing Lake Powell reservoir at the Arizona-Utah border. That water had been scheduled to flow to Lake Mead for delivery to cities, farms and tribes in the Lower Colorado River Basin states of Arizona, California and Nevada.

That means Lake Mead will get 7 million acre-feet from Powell in the water year 2021-22, which ends Sept. 30, 2022 — the lowest release from Powell in many years. But at least for the rest of this year and into next year, the cuts in deliveries from Powell won't reduce the amount of water Arizona cities and farms get from CAP -- Lake Mead will simply absorb the cuts and fall lower.

The U.S. Bureau of Reclamation and the river’s four Upper Basin states signed off on a related proposal to send a half-million acre-feet to Powell from the Flaming Gorge reservoir upstream, at the Utah-Wyoming border. The water will leave Flaming Gorge between May 1, 2022, through April 30, 2023.

Both actions almost certainly insure Powell will get through the upcoming year if not longer without falling below 3,490 feet. That’s the level at which Glen Canyon Dam could no longer generate electricity. Today, Powell stands at about 3,522 feet, more than 75 feet below where it stood two years ago, as arid conditions in the West have reduced flows into the 59-year-old reservoir. It is 24% full, holding about 5.75 million acre-feet or nearly 1.9 trillion gallons of water.

Also, Interior Department officials had expressed concerns that operating the dam with the lake that low could imperil much of the dam’s concrete and steel infrastructure. Below 3,490 feet, Powell’s water would have to be routed downstream through a set of four outlet tubes, lying away from the dam’s turbines, that have never handled water for an extended period before.

“It should get us through the low period right now to March and April 2023 and significantly reduce” the chance of Powell falling below 3,490, said Eric Kuhn, former general manager of the northern Colorado-based Colorado River Water Conservation District. “But if we had another bad year in winter 2022-23, there’s still a chance it could go below 3,490 in the winter of 2023-24.”

In a statement accompanying the public release of the states’ letter to Trujillo, Arizona Department of Water Resources Director Tom Buschatzke said: “The Basin States’ response agrees immediate action is necessary to support operations at the dam . . . While the emergency responses receiving consideration from the Secretary of the Interior are unprecedented, more work is required across the entire Colorado River Basin to ensure the stability of the system. In the Lower Basin, significant additional conservation is required to support the elevations in Lake Mead, now and for the future.”

There are two separate problems on the river right now, said John Fleck, an author and former head of the University of New Mexico’s Water Resources Research Program. One is to protect the dam’s physical infrastructure and to maintain its power generation, “and these actions at Flaming Gorge and holding back water from Lake Mead helps a great deal with that problem.

“We have another problem, related to this problem — the imbalance between supply and consumption. That is why the reservoir is going down. These moves do nothing for that,” said Fleck.

In the seven states’ letter to Trujillo, their water leaders recounted past efforts to get a handle on the problem of declining river flows and reservoirs. Those include the 2007 guidelines they approved that set the first threshold levels in Lake Mead where shortages in deliveries will be declared; the 2019 Drought Contingency Plan, which instituted a series of Lower Basin cutbacks that take effect as Lakes Mead and Powell keep declining; and a plan to compensate water users for saving up to 500,000 acre feet in the Lower Basin this year.

But the letter added, “Our collective efforts notwithstanding, record low runoff, particularly over the past two years, has contributed to historically low storage in Colorado River reservoirs. We appreciate your continuing efforts to work closely with each of the Governor’s representatives as we face extraordinary circumstances on the Colorado River as a result of historic drought, low-runoff conditions, and depleted storage over the past two decades.”

The four Upper Basin states of New Mexico, Utah, Colorado and Wyoming approved the 500,000 acre-foot release of water from Flaming Gorge to Powell as part of what they call a Drought Response Operations Plan. The Interior Department must approve that release, but that is likely a formality at this point.

“Developing the 2022 Drought Response Operations Plan is an unprecedented and significant action by the Upper Colorado River Basin states to protect the Colorado River System for all who rely on it,” said Rebecca Mitchell, Colorado’s representative to the four-state Upper Colorado River Commission that manages Upper Basin water issues.

When added to 161,000 acre-feet released last year from Flaming Gorge and Blue Mesa Reservoir, near Gunnison, Colorado, Mitchell said: “The Upper Basin has contributed 661,000 acre-feet of water to protect critical elevations at Lake Powell. The Upper Basin States are doing our part to protect the Colorado River system.”

Flaming Gorge sits on the Green River and is designed mainly for electric power production and water storage, with a power regime that’s aimed at also protecting habitat for the river’s imperiled native fish.

Unlike Lakes Powell and Mead, Flaming Gorge’s water levels have been relatively stable. The reservoir currently holds slightly below 3 million acre-feet and is about 78% full.

Theoretically, the reservoir could release a half-million acre-feet annually for five or six years before reaching dangerously low levels, although Kuhn said, “I don’t think they have six years” to keep delivering water from Flaming Gorge to Powell while authorities search for longer-term solutions.

“I think this gives them another year, maybe two at the most, of continued well below average hydrology for planning,” Kuhn said. “I think one of the advantages, one of the good things about this, is that they’re leaving some water in Flaming Gorge for future years if they need to draw on it.

“Reclamation has left themselves with the ability to do this again through 2024. At some point, they are going to run out of those options — they aren’t going to be there.”

Utah’s Upper Colorado River Commissioner, Gene Shawcroft, was quoted by KUNC radio in Fort Collins as lauding a spirit of collaboration between the upper basin states. While the U.S. Bureau of Reclamation “had the pen most of the time,” Shawcroft said the four states were involved in every word of the agreement and worked collaboratively so the federal government was not in greater control of their fates.

But Utah environmentalist John Weisheit said the reclamation agency and the states are operating on hope and prayers.

“I think it’s totally ridiculous. Five hundred thousand acre-feet (from Flaming Gorge) is going to do nothing but delay the inevitable,” said Weisheit, director of the Moab-based Living Rivers, which advocates draining Lake Powell and sending its water to Mead to restore Glen Canyon upstream and to reduce evaporation in the reservoir system.

“They are burning the furniture to stay warm. It’s desperation. These managers are responsible for 40 million people living in the Colorado River Basin, and they are failing.”

Colorado River researcher Brad Udall added the federal government's moves make sense for one year but that beyond that, it's time to find longer-term fixes for the depleted river.

"I worry that we’re looking for spare quarters in ash trays rather than finding long term solutions," said Udall, of Colorado State University.

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Contact Tony Davis at 520-349-0350 or tdavis@tucson.com. Follow Davis on Twitter@tonydavis987.