The mountains that feed the Colorado River are buried under an encouraging blanket of snow, but Southern Nevada Water Authority officials aren’t getting their hopes up just yet.
Snow levels at the headwaters of the river are almost 40 percent above average for this time of year, and forecasters predict that could translate to 10 percent more water than the Colorado carries in an average year.
“This would be one of the best years in the last 10 if it holds up, but it’s still very early,” said Rick Holmes, the authority’s deputy general manager for engineering and operations.
“We’re cautiously optimistic, but we’re not holding our breath,” said authority General Manager Pat Mulroy.
The Colorado River Basin receives the bulk of its heavy, wet snow from January to April. The river has flowed at 69 percent of normal during the past 11 years of record drought in the region.
Roughly 90 percent of the Las Vegas Valley’s drinking water supply comes from the Colorado by way of Lake Mead.
Mulroy said a good year on the river like the one that’s shaping up right now would help the reservoir recover somewhat and stave off the first-ever federal shortage declaration on the Colorado.
Since 2000, the surface of Lake Mead has dropped almost 125 feet. It now sits at 1,089 feet above sea level, 40 percent of its capacity and 14 feet above the trigger point for a shortage that would cut allocations for Nevada and Arizona.
Mulroy said river users have seen such promising starts before, only to have the precipitation slow and the snow on the ground literally vanish into thin air.
Even if higher flows fail to materialize in the spring, Mulroy said, a new water sharing agreement with Mexico and commitments by river users in Nevada, Arizona and California should be enough to keep Lake Mead above the shortage line at elevation 1,075 for another year.
Meanwhile, water use continues to decline in the valley, where the water authority delivered about 3 percent less water in 2010 than it did in 2009.
Some of that might be because of higher than average rainfall last year, though virtually no rain fell during the summer, when water demand is at its peak.
Almost 6 inches of rain fell last year at the official weather station at McCarran International Airport. The valley’s average annual rainfall is about 4.5 inches.