Continued drought depletion of Colorado River bodes ill for California

In another sign of trouble for California’s scarce water supplies, top Arizona water officials said worsening depletion of Colorado River reservoirs will require serious action to address the effects of a 22-year mega-drought that shows no signs of letting up.

Federal projections show that Lake Mead and Lake Powell, the nation’s two largest reservoirs, will continue to decline in the coming months, reaching a level of scarcity that could trigger deeper water cuts in 2023 for the United States. Arizona, Nevada and Mexico – and which could also eventually force similar cuts reductions in California.

“The gravity of the immediate situation is serious,” said Tom Buschatzke, director of the Arizona Department of Water Resources. “We expect that further significant actions to reduce water consumption will be required.”

The Colorado River provides water for nearly 40 million people, flowing to cities, farmlands and tribal nations from the Rocky Mountains to Southern California. For decades, the river has been chronically overexploited. So much water is diverted that the river delta in Mexico largely dried up decades ago, leaving only scattered natural wetlands in an otherwise dry river channel that cuts through farmland.

State and federal officials speak at a meeting in Phoenix on Friday, three days after the Federal Office of Reclamation announced plans to reduce the amount of water discharged from Lake Powell this year to reduce the risk of the reservoir water level dropping too low at the Glen Canyon Dam. . Last year the dam produced enough electricity to supply more than 300,000 homes, something it could not do if water levels dropped so much that it could no longer generate electricity .

Buschatzke added that more needs to be done to protect water levels in Lake Mead, which releases water that flows into Arizona, Nevada, California and Mexico.
Lake Powell, which straddles the Arizona-Utah border, has shrunk to just 24% of its full capacity, the lowest point since it was filled in the 1960s following construction from Glen Canyon Dam.

Water that is released from Lake Powell passes through the Grand Canyon and reaches Lake Mead near Las Vegas. Lake Mead has fallen to 30% of its full capacity, its lowest level since it was filled in the 1930s during the Great Depression.

Latest projections, Buschatzke said, show reduced water discharge from Lake Powell will result in a drop of approximately 22 feet in the level of Lake Mead.

“It’s about maintaining Colorado River flows, including through the Grand Canyon,” Buschatzke said. For if flows were to be severely restricted, Lake Mead’s declines would accelerate.

Buschatzke noted that the surface of Lake Mead now sits just under 1,054 feet above sea level. If the reservoir fell to 895 feet, he pointed out, it would reach “dead pool.” – the point at which water would no longer pass through the Hoover Dam.

The federal government’s latest plan will involve releasing about 500,000 acre-feet of water from the Flaming Gorge Reservoir, which is located upstream, and retaining an additional 480,000 acre-feet in Lake Powell.

California, Arizona and Nevada used 6.8 million acre-feet of water from the Colorado River in 2020. (Each acre-feet is enough water to cover a football field about 1 foot depth.)

If Lake Powell were to descend to lower levels, below an elevation of 3,490 feet, water could still be routed through four 8-foot-wide pipes, the river outlet of the dam works.

“However, if the lake were to decline, that ability to release water would diminish,” said Daniel Bunk, Boulder Canyon operations office chief for the Federal Office of Reclamation. “There is a lot of uncertainty with operating below this level.”

In recent years, state and federal officials have repeatedly brokered agreements to try to reduce the chances of Colorado River reservoirs falling to extremely low levels.

In 2019, representatives from the seven states in the Colorado River Basin signed a set of agreements called the Drought Contingency Plan, which included a pact between California, Arizona and Nevada to take less river water. Mexico has agreed, under a separate agreement, to contribute by leaving some of its water in Lake Mead.

As reservoirs continued to drop, water officials in California, Arizona and Nevada signed another agreement in December to again take less water from the river.

Despite these efforts, reservoirs continued to decline.

Scientists have found that higher temperatures caused by climate change are making the watershed worse than it would otherwise be. They say the warmer atmosphere is effectively “thirstier,” drying out soils and evaporating moisture from the landscape, reducing flows in streams and the Colorado River.

“We’re getting much less runoff than precipitation, which is a very concerning trend and something that will be difficult for us to manage the river in the future,” Buschatzke said.

Last year, the volume of inflow into the reservoirs was the second lowest on record, at just 32% of the average. This year the snowfall was just a little below average, but the influx of it should be just 62% off average, Bunk said.

“We seem to be getting precipitation, but other factors like warmer temperatures, dry ground conditions…they all seem to be conspiring, to some degree, against the actual runoff,” he said.

Buschatzke said the South West had to adapt.

“Our future is probably what we would now call living with shortages,” he said. “We all need to come together to help solve these Colorado River problems.”

Arizona gets about 36% of its water from Colorado. Farmers in parts of the state are facing drastic reductions in Colorado River water, drilling wells to try to make up some of the shortfall.

This year, water delivery cuts in Arizona total more than 800,000 acre-feet, about a quarter of the state’s total distribution.

So far, the cuts have largely not affected Arizona cities, but officials said the state may eventually seek to reduce outdoor water use.

“We need to dig a little deeper, be even more innovative and creative,” said Ted Cooke, executive director of the Central Arizona Project. “Additional voluntary conservation is necessary and may delay larger mandatory shortages.”

Buschatzke said the state is preparing for further reductions next year, and even greater reductions could occur in the region in 2024.

He noted that California is on track to use more than its allotment of 4.4 million acre-feet this year, as state agencies take some of the water they have saved in Lake Mead, as permitted by the 2019 drought agreement.

California has stored 1.3 million acre-feet in Mead and will take about 250,000 acre-feet of that water this year to help as the state’s other supplies have dwindled during the drought, said Bill Hasencamp, manager. of Colorado River Resources for the Metropolitan Water District of Southern California.

“We only take a small portion of the water that we put into Lake Mead,” he said.

“We are asking our customers to increase retention this year. But despite the increased conservation, we need that extra water from the Colorado River,” Hasencamp added. “We put it in there for a dry day, a dry year like this year, and that’s why we have to take it out.”

Nearly two weeks ago, the water district declared a shortage emergency and ordered restrictions on outdoor watering to conserve Northern California’s limited supplies that are delivered through the State Water Project. The restrictions, which will vary for each water agency, are set to go into effect June 1 in parts of Los Angeles, Ventura and San Bernardino counties.

Other areas of Southern California that rely primarily on water from the Colorado River are not subject to the restrictions. But the Metropolitan Water District has urged everyone in the area to cut their water usage by 20%.

Buschatzke, Arizona’s water official, said his state wants to avoid the harsh restrictions currently being implemented in California.

“We don’t want to live on health and safety water allocations in our state. And we could be there at some point in the future,” Buschatzke said. “We are committed to doing everything possible to avoid this outcome.”

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