Climate, demands affect Colorado River
Summit County correspondent
Aspen, CO Colorado
SUMMIT COUNTY ” There’s good news and bad news when it comes to the state of the Colorado River this year, depending on your geographic perspective. At the very upper end of the system, above-average snowfall helped boost the snowpack.
“We’ve had a pretty good water year on the Blue River,” said water commissioner Scott Hummer, launching a series of talks at the state of the river meeting in Frisco Wednesday evening. “We’re the leader on the West Slope,” Hummer said, adding that the South Platte Basin is the wettest drainage anywhere west of the Mississippi this year.
The snowpack above Dillon Reservoir is at about 95 percent of average for this date and stream flows in Summit County’s Colorado River tributaries are flowing well above historic means, Hummer said.
Denver Water engineer Marc Waage said he expects Dillon Reservoir to fill early, and there is some concern about the potential for flooding in neighborhoods north of Silverthorne. Green Mountain Reservoir should be filled by early July and stay that way through most of the summer recreation season, said the Bureau of Reclamation’s Ron Thomasson.
And since Colorado Springs won’t be taking its full allotment from the headwaters of the Blue around Hoosier Pass, there is also potential for flooding in the town of Blue River this year.
But the local watershed is an exception. Zooming out to some maps that showed the entire western half of the U.S., it’s clear that the larger region is still in the grip of a serious and widespread drought.
Whether or not that drought is related to climate change or global warming is not clear. But the fact is that the Earth has experienced its 12 warmest years ever during the past two decades, said Dr. Andrea Ray, a researcher with the National Oceanic and Atmospheric Administration (NOAA).
Ray said some of the most recent research coming from the International Panel of Climate Change (IPCC) suggests that the rate of warming is increasing.
“Warmer and fewer cold days are virtually certain,” she said, recapping some of the findings from the latest IPCC reports. Those temperature trends won’t be spread evenly across the entire planet, she said, interpreting models showing that some regions may even become a bit colder.
But the global data is mirrored closely by studies of temperature records in north-central Colorado. Colorado-based NOAA researcher Klaus Wolter recently studied temperature records from a number of sites in this region, and after throwing out unreliable data, still found some unequivocal evidence that a strong warming trend has persisted in the north-central part of Colorado for about 50 years, base on temperature records from Grand Lake, Hayden, Steamboat Springs and Walden.
In that span, average low temperatures have climbed by about five degrees, and astounding one degree per decade, while average highs have climbed about two degrees.
Wolter said the warming is most pronounced in the winter and especially in the spring, and the impacts have already shown up in a trend toward earlier snow melt and runoff, well-documented by the U.S. Geological Survey.
On the global scale, scientists are increasingly confident that greenhouse gases generated by human activities are a significant part of the warming trend.
Ray said the computer models show that other sources, including solar forcing (changes in the energy output from the sun) and volcanic influences simply don’t account for the changes in global temperatures.
Based on the projected temperature increases and streamflow changes, it may not be possible to fulfill all present-day water demands in the region, Ray said.
Part of her research efforts have focused on the ability to adapt to the impending changes, she explained.
“There is room for adaptive capacity with regard to water use,” Ray said. But what’s lacking so far are comprehensive estimates as to the costs and benefits of adaptive measures, she concluded.
In the bigger regional picture, those shortages could play out in the ongoing battle over water use between the Upper Colorado River Basin states and the lower basin, said Glenwood Springs water attorney Scott Balcomb, who represents Colorado in those talks.
Balcomb warned that the Colorado is already over-allocated and said every future water developer should realize that new claims may not be available for extended periods of time.
“We’ve got to make a plan that sufficiently flexible to deal with potential climate change,” Balcomb said.
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