Lake Mead Edges Closer to Historic Low Level, Raising River Concerns

Lake Mead. The white ring

Rose Davis / Bureau of Reclamation

Lake Mead. The white ring “around the tub” shows how much elevation the surface of the lake has lost.

Lake Mead, the vast reservoir behind historic Hoover Dam outside Las Vegas, is flirting with historic low levels. And that doesn’t bode well for any of the seven states (or Mexico) that share Colorado River water.

The surface elevation of Mead July 7 was 1,082.19 feet, or about 40 percent full, with a historic low of 1,080 reached in 2010. But more important, it isn’t that far away from 1,075 feet, at which point the U.S. secretary of the interior could declare a shortage on the river.

The first-time ever declaration could suspend or alter “the Law of the River,” the infinitely complex and arcane set of 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 Bureau of Reclamation, which operates Hoover Dam, has in fact projected that Lake Mead will match the historic 1,080 low by November, with the possibility of hitting the 1,075  benchmark sometime next year, said spokeswoman Rose Davis. The river has been stressed by drought dating back to 2000, and by population growth in the Southwest that is only going to increase.

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.

“I would argue vociferously that the 20 percent decline is due at least in part to climate change we are already experiencing,” said Brad Udall, senior fellow at the University of Colorado Law School and a foremost authority on Western water.

“The problem with Lake Mead is that it’s overused by 1.2 million acre feet every year,” Udall said in an interview with Rocky Mountain PBS I-News. “With increased demands and with climate change, it’s a double wallop. What do we do with this 1.2 million acre-feet deficit?”

That’s a question that has drawn a lot of conversation. But for starters, Arizona would take it in the shorts.

When Congress approved the Central Arizona Project in 1968, the result was a 336-mile long concrete aqueduct that serves Phoenix and Tucson. In exchange, Arizona agreed to move to the back of the line with its water rights.

“Under the 1968 law, we’ll be shutting down the entire Arizona supply before California loses one drop,” said Udall. “That is not politically tenable, it’s not economically tenable. It’s idiocy, actually.”

If a shortage is declared, and depending on how dire it becomes, the situation could only grow worse. At 1,000 feet, Lake Mead would become a “dead pool,” a nightmare scenario in which it 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.

But that could never happen, right, the loss of another 82 feet?

Well, in 2000 Mead was 91 percent full at 1,210 feet, and that was 128 feet ago.

The other half of the equation is Mead’s upstream counterpart, Lake Powell. Powell can be thought of as the bank through which the upper basin states – Colorado, Wyoming, Utah and New Mexico – pay the water they owe to the lower basin, California, Arizona and Nevada. In a typical year, that amounts to some 8.23 million-acre feet.

Thanks to a good snow year in the Upper Colorado River Basin, Powell is now in better shape than Mead. On July 6, it was 52 percent full and had been rising with  snowmelt at about a foot per week.

Even so, the years 2000-2013, in terms of inflow to Powell, were the lowest since the closure of Glen Canyon Dam in 1963. That ranged from 24 percent of average in the extreme drought and wildfire year of 2002 to 147 percent of average in the great snow year of 2011.

One proposal being floated by the Glen Canyon Institute, an environmental group in Salt Lake City, that would surely meet fierce resistance in the upper basin calls for draining Powell to keep Mead full.

“If you’re really pretty smart you might fill Powell first, because there’s more evaporation at (the lower elevation) Mead,” said Udall. “But filling Mead first would uncover Glen Canyon. That’s their goal.”

More fundamental to any solution is examining the basic principle that undergirds the Law of the River – first in time, first in right – a very serious version of “first dibs.”

“The West was settled by agriculture, and oftentimes agriculture still holds the most senior water rights,” said Udall. “It made sense when many were farming and before the West was full of people. About 70 percent of the river’s water goes to agricultural uses.”

The holder of the most senior right has the highest priority, and the most senior water right in the lower basin is held by California’s Imperial Valley Irrigation District, Udall said.

“At the end of those priorities are Los Angeles and San Diego and some 20 million people. It’s nonsensical that you’d shut off Los Angeles and San Diego, while in the California scheme of things, the Imperial would get off scot-free. Over time, the first in time, first in right rule has created major inequities and diseconomies that have to be dealt with.”

Either that or pray for several consecutive years of amazing snowpack.

“That would correct the situation,” said the Bureau of Reclamation’s Davis.

Said Udall, “The other way to look at this is that the glass is half full. We still have 80 percent of the river, still a lot of water. But we’ve got to use it correctly, and that means a healthy agriculture industry that doesn’t use 70 percent. It could be a system in which agriculture is paid handsomely not to plant in very dry years. We need to do better in using water wisely.”


Update: A previous version of this post said incorrectly that the Bureau of Reclamation had projected Lake Mead would hit the 1,075 shortage declaration level by January, 2015.

3 thoughts on “Lake Mead Edges Closer to Historic Low Level, Raising River Concerns

  1. Poor LA and San Diego! What ever happened to desalinization? With the oceans rising and the lakes falling, it would seem an ideal solution for them.

  2. I visited Los Angeles in March this year & despite the acknowledged serious drought conditions many public fountains shot precious water into the air on an 80 degree days where evaporation easily stole some of the recirculating water. It’s time for folks in Las Vegas & LA to turn off their “water features” (yes you, Mirage dancing fountains & Disney’s water curtain) and get serious about water conservation.

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