Holiday travelers hate it, but heavy snowfall in the Rocky Mountains is usually good news to water managers along the Colorado River.

Usually, but not always.

What Denver residents are calling the Blizzard of 2006 probably won't do much to help the Colorado River recover from drought, federal water supply forecasters said Friday.

The storm closed airports and snarled traffic across Colorado, New Mexico and Wyoming, but nearly all of its snow fell east of the Continental Divide, so its water content will never find its way into the river.

"There's pretty huge snowfall amounts, like 32 inches of new snow on the east side of the Rockies, but relatively less -- maybe a foot or two -- on the west side," said Tom Pagano, water supply forecaster for the U.S. Department of Agriculture's Water and Climate Center in Portland, Ore. "In terms of actually draining into the Colorado River, there isn't a lot of that going on."

The Las Vegas Valley gets about 90 percent of its drinking water from the river by way of Lake Mead.

Seven years of record drought have left Lake Mead and its twin reservoir upstream, Lake Powell, at less than 60 percent of capacity. Recovering from that will require several straight years of above-average snowfall and water runoff in the Rockies.

Pagano said it's too soon to know how this year's snow supply will measure up.

"We don't have an official forecast out yet for the season, but when you look at the snowpack we're seeing around different areas, it's pretty middle of the road in terms of historic perspective for this time of year," he said. "I'd be surprised if the forecasts for January first weren't all that far off from normal, which of course leaves room for lots of changes for the rest of the season."

Jan Curtis, applied climatologist for the Water and Climate Center, said the river gets much of its flow from the heavy, wet snow that typically blankets the mountains from March to May.

The center maintains hundreds of remote sensors that collect snow and soil-moisture conditions across the West. The data are used to forecast how much water will flow into the Colorado and other river systems that feed farms and cities in the region.

As of Friday, the Colorado River basin had received 114 percent of its normal precipitation but accumulated only 89 percent of its normal snow-water content for this time of year.

"A lot of the precipitation that's been falling has been rain, not snow," Curtis explained.

The National Oceanic and Atmospheric Administration is predicting a wet winter for the Southwest, but Curtis said that so far there have been "no signs of that developing."

"Keep in mind, that is a forecast based on statistics, and (in statistics) the opposite can also occur," he said. "That's what makes weather forecasting so difficult."

Bill Rinne is the Southern Nevada Water Authority's new director of surface water resources. Before that, he spent 28 years with the U.S. Bureau of Reclamation, including a recent stint as the bureau's acting commissioner.

Rinne said his philosophy is "it's always good to get snow in the mountains," but "it really is a little early to say" how much water the river might get.

As for this week's blizzard, Rinne echoed Pagano's prediction.

"You just can't hang your hat on this particular storm and say it's going to do much for us," he said.