Lake Mead, the vast reservoir behind iconic Hoover Dam outside Las Vegas, is holding its own in later summer, after plummeting in July past levels not seen since it first filled in the 1930s.
The surface elevation of Lake Mead reached the historic low of 1,081.75 feet above sea level during the week of July 7, according to the Bureau of Reclamation. On Aug. 13, the bureau reported the level at 1,080. But as of Wednesday, it had inched back to 1,081.31.
This is all being closely watched by the seven states and Mexico that share Colorado River water. Should Mead fall to 1,075 feet it would trigger a declared shortage on the river, at which point water deliveries could be impacted.
The lake has dropped 128 feet since 2000, during the prolonged drought over big stretches of both the upper and lower basins. But the Upper Colorado River Basin runoff this spring and summer was 94 percent of average, compared to only 47 percent in 2013 and 45 percent in 2012.
Last month, the bureau said it expected a release to Mead from upstream Lake Powell of 8.23 million acre feet during water year 2015, an improvement on the 7.48 million acre feet for water year 2014.
The water year begins Oct. 1. An acre feet is generally considered sufficient water for a suburban family of four for a year.
But even with enhanced deliveries from Lake Powell, the bureau has projected that Mead will continue to fall in 2015.
In an interview with Rocky Mountain PBS I-News, Brad Udall, a Western water expert and senior fellow at the University of Colorado School of Law, summed up Lake Mead’s dilemma.
“The problem with Lake Mead is that it’s overused by 1.2 million acre feet every year,” Udall said. “With increased demands and with climate change, it’s a double wallop. What do we do with this 1.2 million acre-feet deficit?”
Ultimately, it might mean revisiting “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.