Drought news: Hope and angst for the upcoming snowpack season up and down the #ColoradoRiver Basin

From the Las Vegas Review-Journal (Henry Brean):

After 14 years of record drought, it will take an unusually wet year — one like the basin saw in 2011 — to stave off the first-ever water shortages on the overdrawn river and slow the decline of its two main reservoirs.

Lake Mead, the source for 90 percent of the Las Vegas Valley’s water supply, has seen its surface fall by more than 100 feet since the drought began. Current projections call for it to lose another 25 vertical feet of water and sink to a record low by November 2014.

Should the lake keep falling from there, it could force the shutdown of one of two intake pipes used to deliver water to the valley. The Southern Nevada Water Authority is rushing to complete a new $817 million intake that will draw from the deepest part of the reservoir, but the complicated project is unlikely to be finished until late next year or early 2015.

“This is an alarming trend, and one that we would really like to see come to an end,” said water authority spokesman J.C. Davis. “Even if we have an ‘average’ year on the Colorado this year, Lake Mead is projected to continue falling. In order to make a significant dent, we would need at a minimum something on the order of 150 percent of normal.”

Almost all of the river’s flow starts as snow that collects in the mountains of Colorado, Utah and Wyoming from November to late May. Lake Powell, on the Utah-Arizona border, fills with that water in early summer, rising sometimes by a foot or more a day as the snow starts to melt and water flows downstream…

Pennsylvania-based AccuWeather, which supplies data for the Las Vegas Review-Journal’s daily weather page, is forecasting a wet, snowy season in the Northwest, the Rockies and in California, where heavy precipitation in December and January could help fill reservoirs drained by dry conditions in that state…

Just don’t get your hopes up quite yet, Goodbody said. “I’d be reluctant to put a whole lot of stock in forecasts like that. They’re fairly low-skill.”

Long-range forecasts for the Rockies are tricky because the mountains rest between two areas generally influenced by the El Niño and La Niña weather phenomena. It’s even more complicated right now, Goodbody said, because the climate is in what he called a “neutral phase” between El Niño and La Niña.

But the stage is set for a good winter on the Colorado.

The heavy downpours that triggered devastating floods in eastern Colorado last month also soaked the headwaters for the river, moistening soil left parched by the long dry spell. Goodbody said that could allow more snowmelt to flow down into the river system rather than be absorbed by the dry ground.

The flow of water into Lake Powell was more than twice what it normally is in September, which is the driest month of most water years but ranked as the third wettest of water year 2013.

That’s almost unheard of, Goodbody said, and it serves to illustrate just how unusually wet September was and how unusually dry it was during the rest of last year.

More Colorado River Basin coverage here and here.

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