Lake Mead water level estimates due Monday

By Conor Shine

Friday, Aug. 14, 2015 | 2 a.m.

With Lake Mead's elevation hovering just three feet above a critical threshold that would trigger mandatory cuts in water supplies, Colorado River watchers are anxiously awaiting new projections from the Bureau of Reclamation due out Monday that will guide operations on the drought-stricken system for the next year.

Although the Bureau of Reclamation releases updated projections for the river each month, the August study is the most important, providing data that will help determine how much water is discharged from the upstream Lake Powell reservoir into Lake Mead during the following year.

"It provides water managers and users of the Colorado River some certainty in understanding and anticipating how river operations might affect lake levels," said Southern Nevada Water Authority spokesman Bronson Mack, who added that the information helps his agency react to changes in water quality.

While Lake Mead hit record lows this spring and projections showed the greatest chance ever of triggering the mandatory water cuts next year, it's expected the levels predicted in Monday's report will be safely above the threshold.

Thanks to an especially rainy May, the volume of water flowing through the river has improved slightly, meaning the chance that Lake Mead could dip below 1,075 feet in elevation this year, once a distinct possibility, is now remote. The most recent projections show Lake Mead's elevation at 1,083 feet in January, the start the Bureau of Reclamation's water year.

Even though cuts aren't likely next year, the health of the Colorado River is still in jeopardy following 15 years of severe drought that have comprised the driest stretch in over 100 years. "The total combined storage in both reservoirs is still at its lowest point in history and it's going down every day," said Gary Wockner, executive director of the nonprofit advocacy group Save the Colorado. "There is no real hope on the horizon that the system has stabilized. The situation is getting worse, just not as fast as it was."

Current projections show that Lake Mead's elevation — which currently sits at 1,078 feet — will dip below 1,075 feet as soon as April, but water restrictions won't be enacted unless the reservoir is below that level starting in January of a given year.

"In all likelihood, it's a matter of when, not if," Wockner said, despite conservation measures enacted in California and other Western states. "No one's making new water. They're just re-apportioning the water they're already taking out of the system."

Western states agreed to a system of mandatory cuts of Colorado River water use in 2007. Were the level to dip below 1,075 feet, Las Vegas would lose about 4.5 percent of its annual allocation of 300,000 acre-feet (one acre-foot is equal to 325,851 gallons, roughly the amount that two Las Vegas homes use in a year). Arizona would face an 11.5 percent cut to its supply.

Because Las Vegas currently does not use its full allocation of river water, if mandatory cuts were triggered, residents would not feel the effects immediately.

Further cuts would be implemented were Lake Mead's water level to drop below 1,050 feet and again at 1,025 feet.