PHOENIX – Lake Mead has fallen to its lowest level since the reservoir was filled in the 1930s following the construction of the Hoover Dam, marking a new milestone for the water-deprived Colorado River in a downward spiral that shows no sign of loosening.
The reservoir near Las Vegas holds water for towns, farms, and tribal lands in Arizona, Nevada, California, and Mexico. Years of relentless drought and higher temperatures due to climate change are reducing theflow into the lake, contributing to Colorado’s large mismatch between water demands and dwindling supplies.
The lake’s rapid decline exceeded expectations just a few months ago. Its surface hit a new low on Wednesday night when it surpassed the altitude of 1,071.6 feet, a record set in 2016. But unlike that year, when the inflows helped push the lake level up. , the watershed is now so parched and depleted that East Mead is expected to continue declining next year and into 2023.
Lake Mead, the largest reservoir in the country, now represents only 36% of its full capacity.
Previously:The Hoover Dam, a symbol of the modern West, faces epic water shortage
Federal government expected to declare official Lake Mead shortage this summer
Over the past month, Mead has already fallen below the official shortage line, which the federal government is expected to declare in August. This will trigger major cuts in water allocations for Arizona, Nevada, and Mexico next year. And even larger water cuts could be imposed on the southwest if the reservoir continues to decline, which the government estimates are likely.
“It should represent an earthquake in people’s sense of urgency, on all fronts,” said Felicia Marcus, visiting researcher in the Water in the West program at Stanford University.
The continued decline of the reservoir, Marcus said, should sound “alarm bells” across the West that the days of usual approaches are over and “we need to speed up whatever we can to use less water.”
This includes accelerating efforts that cities and water agencies are already undertaking in parts of the southwest, such as investing in recycling wastewater, capturing stormwater, or cleaning up polluted groundwater, a declared Marcus. And that also includes promoting conservation and more efficient use of water in a variety of ways, she said, ranging from investing in water-saving technologies on farms to supply cash back to homeowners to remove grass and replace it with drought tolerant landscaping.
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The Colorado River and its tributaries provide water to cities from Denver to Tucson and approximately 4.5 million acres of farmland from Wyoming to the US-Mexico border. About 70% of the water diverted in the seven US states is used for agriculture, flowing to the hay and cotton fields, orchards and farms that produce much of the country’s winter vegetables.
The watershed has been ravaged by one of the driest 22-year spells in centuries. Scientists describe the past two decades as a mega-drought made worse by climate change, and say the Colorado River basin is undergoing “aridification” that will make water management more difficult for generations to come.
In 2000, Lake Mead was nearly full and its surface was lapping at the gates of the Hoover Dam spillway. Since then, the tank has fallen nearly 143 feet. And it is now at its lowest level since 1937.
Two years ago, representatives from the seven states that depend on the Colorado River gathered at the Hoover Dam to sign a package of agreements called the Drought Contingency Plan, which included measures to take less water and share. reductions during a shortage to reduce risk. of Lake Mead falling to extremely low levels.
But declines continued and drought intensified over the past year, with much of the watershed choking across the 12 driest months in 126 years of records. The river and its tributaries decreased, reducing the flow into Lake Powell on the Utah-Arizona border, in turn causing water levels to drop at Lake Mead.
Climate change means a “thirstier” landscape
Over the past year, declines in water levels have accelerated, exceeding previous estimates due to extremely dry conditions in the Rocky Mountain watershed, where much of the river’s flow comes from melting. snow. Warmer temperatures have made the entire watershed “thirstier,” as climatology researchers say, eroding the river’s flow as vegetation draws more water and more moisture evaporates. of the landscape.
The changes are clearly visible along the shores of Lake Mead, beneath the whitish mineral “tub ring” that covers the rocky slopes of the desert.
In just 12 months, the lake level has dropped almost 20 vertical feet.
The reservoir reached record territory four days earlier than the Federal Bureau of Salvage predicted just over two weeks ago.
To accommodate the changing shores of the Lake Mead National Recreation Area, workers relocated marinas and enlarged boat launching ramps.
“It’s scary that it’s happening so quickly,” Marcus said. “I think people are surprised it’s so bad so soon, because of the role temperature plays in aridification and sublimation – all those big words that just mean it’s so hot, that the substance is sore. ‘evaporates, so even the snow and precipitation that we do get doesn’t get that far.
She said the drop in Lake Mead levels is an emergency and should be treated as such.
“The yellow alert has passed. This is the red alert, ”Marcus said.
The response, she said, should accelerate a series of actions to accommodate a smaller water supply from the river.
“And luckily, for a lot of the things that we use water for, we can use a lot less water and we can use it more times than we do,” Marcus said. “There is a lot of room to become more efficient. It’s just that we are a little in denial about the gravity of the situation. “
“We know what to do. We just have to turn up the volume ‘
During the last severe drought in California from 2012 to 2016, Marcus served as chairman of the State Water Resources Control Board, which adopted mandatory conservation rules for cities and towns. These rules have had a lasting effect on reducing water consumption.
She said representatives from the seven states that depend on the Colorado River have done an impressive job meeting and agreeing on past agreements such as the Drought Contingency Plan. And they’ll soon have to face negotiations again over how to deal with shortages after 2026, when existing rules expire.
Officials from Arizona, Nevada, California and Mexico spoke of other ways to work together on long-term projects to boost water supplies. One idea they are exploring would be for Arizona to work with Mexico to build a desalination plant on the shore of the Sea of Cortez and trade some of the drinking water produced for some of the water from the Colorado River in Mexico.
Officials from the Southern Nevada Water Authority in Las Vegas have offered to invest in a water recycling project in Southern California, which would allow the agency to use some of the river’s water in return. Colorado of the Metropolitan Water District. Arizona water officials are also planning to join the other agencies and take part in the project.
Marcus said various promising efforts are underway and the retreat from the shores of Lake Mead shows the region needs to pick up the pace.
“We have to let go and go faster on all of this,” she said. “We know what to do. We just have to turn up the volume. “
This includes investing in infrastructure projects to reduce reliance on imported water from elsewhere, Marcus said, and investing in better sensor networks so that officials don’t. ” not guess on the basis of outdated models that were not designed for a world facing climate change. “
She offered another analogy for the worsening Colorado River crisis.
“The house is on fire and we’re always rearranging the furniture and thinking, you know, do we want to redecorate the kitchen? Marcus said. “This is not to denigrate all the work that has been done. It’s just that we need to do a lot more.
Follow reporter Ian James on Twitter: @ByIanJames
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