Record May Rain in Colorado, but Lake Mead still Hits Benchmark Low

Lake Mead's water level has dropped 135 feet since 2000.

Visible Earth / NASA

Lake Mead's water level has dropped 135 feet since 2000.

Taking note: From midnight until 2 a.m. Wednesday, the U.S. Bureau of Reclamation reported the surface elevation of Lake Mead at 1,074.99 feet, a new record low. That’s a fraction below the 1,075 benchmark at which the U.S. secretary of the interior could declare a shortage on the Colorado River system.

No one expects the declaration anytime soon. But if Reclamation projects the vast reservoir behind Hoover Dam outside of Las Vegas to be at or below 1,075 feet next January, all bets are off.

By noon Wednesday, the lake level had ticked back up to 1,075.09. Granted, these are tiny differences in numbers. But for observers of the lake, and its upstream counterpart, Lake Powell, as well as for the many environmentalists and others deeply concerned about the health of the Colorado River, it’s like watching the proverbial slow motion train wreck.

A first-time ever shortage declaration could suspend or alter “the Law of the River,” the infinitely complex rules that govern the river’s use, starting with the Colorado River Compact of 1922, and changed by many agreements, lawsuits and rulings since, including acts of Congress and a Supreme Court decree.

The Colorado River Commission, with Secretary of Commerce Herbert Hoover serving as chairman, met in Santa Fe, New Mexico, in the Fall of 1922.

Bureau of Reclamation / U.S. Department of the Interior

The Colorado River Commission, with Secretary of Commerce Herbert Hoover serving as chairman, met in Santa Fe, New Mexico, in the Fall of 1922.

A declaration could change state water allotments, most likely first in Arizona, experts say, because of agreements made in approving the Central Arizona Project, which serves Phoenix and Tucson.

If a shortage is declared, and depending on how dire it becomes, the situation could grow worse. At 1,000 feet, Lake Mead would lose its ability to serve the two million residents of Las Vegas, and Hoover Dam would lose its capacity to generate electricity depended upon in three states.

For that to happen, the surface would have to drop another 75 feet, which is a huge amount of water. But in 2000 Mead was 91 percent full at 1,210 feet. Which means it has dropped 135 feet since then. Las Vegas is constructing deeper intakes from the lake, a hugely expensive project that is ongoing.

Much has been stated lately about the stress on the river, most likely over-allocated between the seven states from the get-go, and punished by persistent drought over the last 15 years. Those concerns are justified.

Annual flows that averaged 15 million acre-feet during the years prior to 2000 averaged about 12 million between 2000 and 2010, a decline of 20 percent, analyses have shown.

Across the Southwest, the nation’s hottest and driest region, abnormal is becoming the rule. Colorado experienced its wettest May in the history of record keeping. Most of California remains at the highest level of drought, D4 or exceptional drought, while much of Nevada is one step below at D3, extreme drought.

Which doesn’t make for one big happy family along the Colorado.

Meanwhile, the Colorado Climate Center reported this week that the river was flowing at 170 percent of average into Utah. That’s a lot of water moving downhill. Stay tuned.

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