When the U.S. Bureau of Reclamation announced last month that the country’s largest reservoir, Lake Mead, had fallen to its lowest-ever level at 1,074ft (327m), the question many asked was: How will it affect one of California’s primary drinking sources?
After all, some 19 million Californians, nearly half the state’s population, receive some part of their water from the Colorado River, which flows into the 80-year-old reservoir created by Hoover Dam outside Las Vegas.
By inching below the 1,075ft threshold, the lake’s historic low provoked a Level 1 Water Shortage declaration, signaling the start of potential water cuts to Arizona and Nevada. If Lake Mead sinks to 1,025ft (312m), the Department of Interior will seize control of its management and water allocation, and if it falls to 900ft (274m) it will be considered “deadpool,” meaning that water is no longer passing through the turbines. Falling water levels are the result of a drought in the Colorado River Basin that has dragged on for 16 years and counting.
For Glen MacDonald, the John Muir memorial chair in geography and former director of the Institute of the Environment and Sustainability at the University of California, Los Angeles, the May pronouncement was “the line in the sand.”
“According to the laws, [California] wouldn’t have to take a cut. But they’re worried if this goes down to 1,045ft, and then 1,025ft, it’s going to be really problematic,” said MacDonald. Like most state water experts, he doesn’t think shortages will be triggered next year, but he isn’t ruling out water cuts in 2018 and beyond. The Bureau of Reclamation reports a 64 percent chance that Lake Mead, with its 60 million acre-foot (74 billion cubic-meter) capacity, will fall below the 1,025ft threshold by 2019, requiring an emergency federal response. Given the unknowns, he said, “this is the best over-the-horizon look we can get.”
The legislation MacDonald referred to, the Colorado River Compact of 1922, handed California senior rights over the river and stipulated that Nevada and Arizona must be the first to make cuts in times of shortage. But if bad turns to worse in the region’s persistent drought, officials are already discussing the possibility of new negotiations taking shape.
“Cuts to California? Not anytime soon,” said Jeffrey Kightlinger, general manager of the Metropolitan Water District of Southern California, which distributes 4 million acre-feet (4.9 billion cubic meters) of water – most of it from Lake Mead – to 19 million customers each year. The crucial period, he said, is between 1,075ft and 1,020ft, because “we have no rules lower than 1,020, so everyone has to talk about next levels of action. The expectation is, at some point, California would likely be sharing the pain as well. [So] while California is not willing to put water on the table, we also agree that we shouldn’t wait until 1,020ft – we should be having the conversation earlier.”
Unofficial proposals that are being floated include eventual Colorado River cuts to California in the range of 300,000–350,000 acre-feet (370–430 million cubic meters) – a little less than 10 percent of the 4.4 million acre-feet the state currently draws from the river. “Losing 10 percent of your water portfolio would be tough,” said MacDonald, who suggested California negotiators may sit down sooner to hammer out a deal, mitigating to avoid the more precarious political impacts of a water crisis engulfing the West.
On the upside, increased rainfall this winter enabled California’s Department of Water Resources to announce in April that it is boosting water delivery to meet 60 percent of requests through the 2016 calendar year – up from 20 percent last year and 5 percent in 2014. (The last time 100 percent of water requests were allocated was 2006.)
Heavy rains brought on by El Niño helped fill key reservoirs in northern California, including Lake Oroville (now at 92 percent capacity), Shasta (90 percent capacity) and Folsom (83 percent). More than two-fifths of California still remains in what the U.S. Drought Monitor calls “extreme drought,” but the State Water Resources Control Board responded to the wet winter by loosening restrictions on water use.
Yet despite the significant relief to the north, that’s not likely to translate into additional water moving south from the Delta to compensate for the eventual shortages caused by a shrinking Lake Mead – not least because of the tenuous recovery and preservation efforts of the Delta’s fragile fisheries. “The allocations are already set from the Delta. There’s not going to be any more allocated,” said Shane Hunt, public affairs officer at the Bureau of Reclamation for the Mid-Pacific region. “We are still dealing with the drought. Just because two of our reservoirs, Shasta and Folsom, are above average doesn’t mean the rest of them are. We’re having a lot of problems delivering to customers.”
MacDonald said it’s physically conceivable, but politically improbable, that more Bay-Delta water will be sent south to offset future demands of Metropolitan. “In a perfect world, if we had cuts in the Colorado River, and we had surplus capacity up in the San Joaquin Valley, you would offset the amount of water needed,” he said. “But nobody here is counting on being able to do that. No rational person is thinking that we’re going to get a lot more water out of the Delta for L.A.”
Kightlinger of Metropolitan agrees. “We don’t see a Delta impact in the near future. Our game plan is that we’ll be making up [the shortage] with more conservation and more recycling,” a process that currently reuses about 400,000 acre-feet (490 million cubic meters), or 10 percent of the region’s water each year, he said. “We expect to have some losses, but to stem our losses best we can. We don’t expect to get more imported water from either the Colorado or northern California.”
So, returning to the original question of how Lake Mead’s historic low will impact California’s crucial drinking source, the best answer may be: in the near term not a whole lot, but in the long term, quite a bit. Still, UCLA’s MacDonald strikes a note of optimism. “This is manageable right now by taking strong action in terms of conservation and infrastructure,” he said, suggesting that if Southern California increases stormwater capture to 300,000 acre-feet by 2025, it could offset the potential 10 percent cut from the Colorado River. But time is of the essence.
“This is it. We’ve seen our vulnerabilities,” said MacDonald. “In a sense, we should take advantage of the drought: If we can learn some lessons, we can put into place some strategies that will get us through this century.”