Lake Mead's Water Level Plunges as 11-Year Drought Lingers
Published: August 13, 2010
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"There's a bit of a perception that folks aren't doing anything about it," said Terry Fulp, deputy regional director of the Lower Colorado Region for the Bureau of Reclamation, the federal agency that operates Lake Mead, Lake Powell and the Hoover Dam. "As we entered this current drought at the start of this decade, it became very apparent we needed at least to sit down and talk about how we are operating the reservoirs and also put some proactive measures in place."
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Nonetheless, scientists contend that the cutbacks called for in the 2007 agreement, euphemized by then-Interior Secretary Dirk Kempthorne as an "agreement to share adversity," are not enough to stop the hemorrhaging.
The lowest reduction mandated by the agreement would cut deliveries by 333,000 acre-feet, about half of what Los Angeles consumes in a year, should the lake's surface fall another 12 feet to 1,075 feet above sea level, or about 33 percent capacity. "Many people think that could happen as early as next year," Udall said.
Greater cutbacks and impacts follow as Mead's surface plunges further. When the 28.5-million-acre-foot reservoir's surface hits 1,050 feet, or about 26 percent capacity, deliveries get slashed by 417,000 acre-feet, Las Vegas shuts down one of its two intakes and Hoover Dam's massive turbines lose the hydraulic pressure needed to generate electricity. The maximum cutback of 500,000 acre-feet kicks in when Mead's surface hits 1,025 feet, or about 20 percent capacity.
Even holding back the maximum 500,000 acre-feet of water -- enough to serve 2 million residents for a year -- accounts for less than a third of the reservoir's current deficit, which is expected to grow as temperatures increase an estimated 2 to 4 degrees Celsius by 2050, as studies predict.
"The cuts that they have proposed are not big enough," said Barnett. Not even close, according to his research. "They're not big enough to cover the climatic effects," he said.
A gamble for Vegas
For Las Vegas, which draws 90 percent of its water supply from the lake, the worst-case scenario would occur if the surface drops below the lower of the city's two intakes to 1,000 feet, cutting off the supply.
The prospect has the Southern Nevada Water Authority pursuing the permits necessary to build a $3.5 billion, 300-mile pipeline to shuttle water from an alternative source in northern Nevada.
Work is already under way on a $700 million project to connect a third intake that would run up through the bottom of the lake, enabling it to be sucked dry. It has been a difficult feat: Last month, construction was halted when workers hit a seam that flooded the excavated cavern. Nobody was injured, although the flood trapped several large pieces of construction equipment underwater.
Scientists and Reclamation officials agree: Las Vegas will not be running dry anytime soon. But that means the spigot on Lake Mead will likely be tightened in the coming years, probably far more than the 2007 agreement calls for.
Even Fulp does not dispute the results of Barnett's most recent study, which predicts that climate change will grow Mead's annual water deficit by as much as 1.5 million acre-feet in 2050, assuming a conservative 10 percent reduction in snow runoff. At 20 percent runoff reduction, the average annual deficit grows by 2 million acre-feet by 2060. According to one of the government's own models, which Barnett cites, Reclamation would be unable to hold Mead's water level above 1,000 feet in a scenario of 20 percent reduction in snowmelt, even if it holds back 3.3 million acre-feet of water.
Studies and models like these prompted Reclamation to launch a two-year study in January that will take a more detailed look at water supply and demand in the region. Fulp said the study will inform decisions about, among other things, how Mead's water gets meted out in the coming decades.
"The risk of losing Lake Mead is negligible," Fulp said. "We're not going to drive this lake into the ground, probably. I don't mean to say it absolutely couldn't happen, but I believe we've got these management options in place so that it wouldn't happen. We would cut deliveries back."
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