Lake Mead At Lowest Level Since 1937, When Biggest US Reservoir Was First Being Filled

Lake Mead—America’s largest reservoir, Las Vegas’ main water source and an important indicator for water supplies in the Southwest—will fall this week to its lowest level since 1937 when the manmade lake was first being filled, according to forecasts from the federal Bureau of Reclamation.



The record-setting low water mark—a surface elevation of 1,081.8 feet above sea level—will not trigger any restrictions for the seven states in the Colorado River Basin. Restrictions will most likely come in 2016 when the lake is projected to drop below 1,075 feet, a threshold that forces cuts in water deliveries to Arizona and Nevada, states at the head of the line for rationing. But the steadily draining lake does signal an era of new risks and urgency for an iconic and ebbing watershed that provides up to 40 million people in the U.S. and Mexico with a portion of their drinking water. The rules governing the river are complex, but the risk equation is straightforward: less supply due to a changing climate, plus increasing demands from new development, leads to greater odds of shortages.

No area is more vulnerable than Las Vegas, which draws 90 percent of its water from Lake Mead. Today, in the midst of the basin’s driest 14-year period in the historical record, the gambler’s paradise is completing an expensive triage. The regional water authority is spending at least $US 829 million of ratepayer money to dig two tunnels—one at the lake bottom that will be completed next spring and the other an emergency connection between existing intakes—to ensure that the 2 million residents of southern Nevada can still drink from Mead as more of the big lake reverts to desert.

EDIT

While the lower basin keeps an eye on Lake Mead, the upper basin is more concerned about water levels in Lake Powell, the second largest reservoir on the Colorado, 180 miles upstream (290 kilometers) from Mead. The upper basin put forward a plan this spring to keep more water in Powell. The states would do this by paying farmers not to farm and by changing how smaller mountain reservoirs are managed. Three urban water utilities in the lower basin, along with Denver and the federal government, put up $US 11 million to develop a similar basin-wide program.

EDIT

http://ecowatch.com/2014/07/07/lake-mead-reservoir-record-low-drought/1/