Denver Water releases outlook for 2012 summer operations; adjusts operations in the north end of its system
By Bob Berwyn
SUMMIT COUNTY — If the drier-than-average weather continues the next few weeks, Dillon Reservoir is unlikely to fill this year, although it should come within a couple feet of maximum storage sometime in June.
With average spring precipitation, the reservoir should fill in June, but it’s unlikely there will be enough water to sustain a lengthy rafting season in the Lower Blue, according to Denver Water, which late last week released a detailed outlook for Dillon Reservoir operations.
NOAA’s Climate Prediction Center is calling for higher than average chance for drier- and warmer-than-average conditions for much of Colorado through May, but that general outlook doesn’t tell the whole story, as one or two wet spring storms can significantly alter the runoff picture.
Under a dry scenario, Denver Water expects the reservoir to reach a maximum elevation of about 9,015 feet in June, then drop rather quickly, by about six feet in July and another seven feet by the end of September.
Even under the dry scenario, water levels would remain high enough for reservoir operations through most of the summer.
With above-normal precipitation through May, the reservoir is projected to fill in June and stay close to maximum capacity through the summer. The provisional outlook is subject to change, depending on developing conditions. For example, a hot and dry summer on the Front Range could result in a quicker draw-down, while a wet monsoon season could reduce the demand for water.
In a message on its website, Denver Water indicated that reservoir storage is above normal for this time of year. But storage is only one indicator of drought and “reservoir levels can drop quickly when we don’t get much snow and rain,” the water provider wrote.
Based on the dry winter in the watersheds that help supply the Front Range, Denver Water said it reduced the amount of water leaving the Moffat Treatment Plant — fed by Gross Reservoir, north of Boulder — to reserve more water in the north end of our system.
According to Denver Water, the north end of the system is more susceptible to supply problems during a dry year, an issue the utility hopes to address with expansion of the Moffat Collection System Project, which would enlarge Gross Reservoir and provide 18,000 acre-feet of additional water supply through increased diversions from the Colorado River Basin.
The last time Dillon Reservoir didn’t fill was in 2004, when it remained about 10 feet below its maximum elevation. That ended a string of three years in a row when it didn’t fill. In recent years, the reservoir has fill as early as May 24 (2010) and as late as July 27 (2012), when Denver Water had to adjust for massive amounts of late-season runoff.
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