Wednesday, Nov. 30, 2005 | 7:57 a.m.
A series of winter storms sweeping across the northern tier of the United States has brought some hope of precipitation for the Colorado River basin, but so far that hope has yet to produce much in the way of wet stuff.
Officials with federal, state and local water agencies hope that the water year that started Oct. 1 will match or exceed last year's inflow into Lake Powell of 105 percent of average.
Last year reversed five years of drought that dropped water levels in Powell -- the Colorado River's upstream reservoir -- and Lake Mead, its downstream reservoir.
Although the drought's effects have been virtually eliminated on the ground in Nevada, moderate drought is hanging on tenaciously to parts of Colorado, Arizona and New Mexico. More troublesome is that the years of drought have sent water levels to historic lows in both lakes Mead and Powell.
Lake Mead is the source for about 90 percent of the water used by the Las Vegas Valley. Overall, the Colorado River provides water to about 20 million people in the West.
The years of drought have left Lake Powell with less than half of its capacity, while Lake Mead is about 60 percent full. The entire river system is at 54 percent of capacity, well below the 92 percent capacity in January 2000.
A bad water year could spell reductions for users and threaten the generation of electricity at Glen Canyon and Hoover dams, which create the river's two huge reservoirs.
So far, the total amount of precipitation that the Colorado River basin has received in the first two months of the water year is about normal -- 99 percent of normal, according to Bruce Williams, daily operations team leader for the Bureau of Reclamation's Boulder Canyon office. The bureau manages river operations and lake levels for the Colorado River.
Williams said it would be premature to judge how the year will go based on the last two months.
"It's early," he said. "It's November, and it's one of the snow-building months. December and January are even bigger. It's off to a good start."
One potential worry is that while overall precipitation is about normal so far, most of it has been in the form of rain. Water system managers would prefer to see snow.
Williams said that to date, the snowpack in the Rocky Mountains of southern Wyoming and Colorado has been about 25 percent below normal.
The results are in line with the National Oceanic and Atmospheric Administration's winter outlook. That forecast, updated Nov. 17, calls for equal chances of greater or lesser amounts of precipitation in the Intermountain West and Rocky Mountains, but a 70 percent chance of above-average temperatures that would lead to rain more than snow.
"The Colorado River depends on snow for its source," said Bob Walsh, a bureau spokesman. "Rains are important, but they're just not as important as snow."
Kelly Redmond, regional climatologist with the Desert Research Institute's Western Regional Climate Center in Reno, said observers would like to see more snow on the ground, especially in the southern Rockies.
"That is what is going to turn into the water that runs into the river in the spring, when most of the runoff occurs," Redmond said.
He said melting snow works better than rain to slowly percolate through the mountain rock, then come out in springs that feed into the main rivers.
Vegetation tends to take more from rainfall than from snow, he said.
"Snow just tends to be a more effective way of recharging the soil moisture column."
Redmond said storms that have been moving through the Northwest this week show promise is bringing more moisture to the upper Colorado River basin.
While he sees a deficit for much of the river basin, "it's the kind of deficit that can be made up relatively quickly," he said.
But the drought's effects still have everyone on guard.
"Although we had a good year, it doesn't take much to take us right back to where we were going before," Redmond said.
Tracy Bower, a Southern Nevada Water Authority spokeswoman, said her agency also is tracking the numbers for snowpack and runoff. Although the agency would like to see higher snowpack numbers, she notes that Tuesday's percentage was "up from 46 percent we saw earlier in the month."
"We'd like to see that number continue to go up," Bower said.
Williams stressed that the winter is just beginning, noting that Mother Nature has a way of throwing a few curveballs into the Western climate.
"It can swing both ways, just like it did last year," he said. "It's hard to really say what a system is going to do until the system arrives."
Launce Rake can be reached at 259-4127 or at [email protected].
archive
