In another sign of serious trouble for California’s scarce water supplies, top Arizona water officials said the depletion of Colorado River reservoirs will require serious action to combat the effects of a 22-year megadrought that shows no signs. to give in
Federal projections show that Lakes Mead and Powell, the nation’s two largest reservoirs, will continue to decline in the coming months, reaching a level of scarcity that will likely trigger further water cuts in 2023 for Arizona, Nevada and Mexico, and could also eventually force similar reductions in California.
“The gravity of the immediate situation is dire,” said Tom Buschatzke, director of the Arizona Department of Water Resources. “We hope that it will apply more actions to reduce the use of water.”
The Colorado River supplies nearly 40 million people with water, flowing to cities, farmlands and tribal nations from the Rocky Mountains to Southern California. For decades, the river has suffered from chronic overexploitation. So much water is diverted that the river delta in Mexico dried up decades ago, leaving only scattered natural wetlands in an otherwise dry river channel running through farmland.
State and federal officials spoke at a meeting in Phoenix on Friday, three days after the Federal Bureau of Reclamation announced plans to reduce the amount of water released from Lake Powell this year to reduce risks of the reservoir’s water level dropping. too much at Glen Canyon Dam. Last year, the dam generated enough power to supply the needs of more than 300,000 homes, something it could not do if water levels drop so low that it can no longer generate electricity.
Buschatzke added that more needs to be done to protect the water levels of 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 after construction. of the Glen Canyon Dam.
Water released from Lake Powell flows through the Grand Canyon and into Lake Mead near Las Vegas. Lake Mead has dropped to 30% of its full capacity, its lowest level since it filled in the 1930s during the Great Depression.
The latest projections, according to Buschatzke, show that the reduction in discharges from Lake Powell will cause a drop of about 6 meters in the level of Lake Mead.
“This is about maintaining flows in the Colorado River, including through the Grand Canyon,” Buschatzke said. Because if the flows are severely restricted, the decline of Lake Mead would accelerate.”
Buschatzke noted that the surface of Lake Mead is currently just under 1,054 feet above sea level. If the reservoir dropped to 895 feet, he noted, it would reach the “dead pool,” the point at which the water would stop flowing through Hoover Dam.
The federal government’s latest plan is to release about 500,000 acre-feet of water from the Flaming Gorge Reservoir upstream and retain another 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-foot is enough water to cover a football field about a foot deep.)
If Lake Powell were to recede to lower levels, below the 3,490-foot mark, the water could still be conveyed through four 8-foot-wide pipes.
“However, if the lake were to shrink, that ability to release water is diminished,” said Daniel Bunk, chief of the Federal Bureau of Reclamation’s Office of Boulder Canyon Operations. “There is a lot of uncertainty in trading below that level.”
In recent years, state and federal officials have repeatedly brokered agreements to try to reduce the risks of Colorado River reservoirs falling to critically low levels.
In 2019, representatives of the seven Colorado River basin states signed a set of agreements called the Drought Contingency Plan, which included a pact between California, Arizona and Nevada to take less water from the river. Mexico has agreed, in a separate agreement, to contribute by leaving some of its water in Lake Mead.
As reservoirs continue to recede, water managers in California, Arizona and Nevada signed another agreement in December to go back to taking less water from the river.
Despite those efforts, the reservoirs have continued to decline.
Scientists have found that rising temperatures caused by climate change are making the drought much worse than it would be in the basin. 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 rainfall, which is a very worrying trend, and something that will challenge river management in the future,” Buschatzke said.
Last year, the flow to the reservoirs was the second lowest in history, with only 32% of the average. Snow this year has been a little below average, but the influx is expected to be only 62% of average, Bunk said.
“It looks like we’re getting the precipitation, but other factors, like warmer temperatures, dry soil conditions… seem to be conspiring, to some extent, against actual runoff,” he said.
Buschatzke said the Southwest needs to adapt.
“Our future is probably what we would now call living in scarcity,” he said. “We have to all come together to help solve these Colorado River problems.”
It is estimated that Arizona gets 36% of its water from the Colorado. Farmers in some parts of the state are coping with dramatic water shortages from the Colorado River, drilling wells to try to partially make up for the shortage.
This year, reductions in water deliveries in Arizona total more than 800,000 acre-feet, about a quarter of the state’s total allocation.
So far, the cuts haven’t affected Arizona cities, but officials said the state could eventually try to reduce outdoor water use.
“We have to dig a little deeper, be more innovative and creative,” said Ted Cooke, CEO of the Central Arizona Project. “Additional voluntary conservation is necessary and can help delay larger mandatory measures.”
Buschatzke said the state is preparing to deal with additional cuts next year, and even bigger cuts could come across the region in 2024.
He noted that California is on track to use more than its 4.4 million acre-feet allotment this year because state agencies are withdrawing some of the water they have saved from Lake Mead, as allowed in the California drought agreement. 2019.
California has stored 1.3 million acre-feet in the Mead, and will draw about 250,000 acre-feet of that water this year to help as the state’s other supplies have been reduced during the drought, said Bill Hasencamp, resource manager. of the Colorado River for the Metropolitan Water District of Southern California.
“We’re only taking a small part of the water that we put into Lake Mead,” he said.
“We ask our customers to increase conservation this year. But despite increased conservation, we need that additional water from the Colorado River,” added Hasencamp. “We have put it there to use it in a dry year like this, and that is 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 delivered through the State Water Project. The restrictions, which will vary by water agency, will 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 region to reduce water use by 20%.
Buschatzke, Arizona’s water chief, said his state wants to avoid the severe restrictions being enforced in California.
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