Colorado likely will heat up 2.5 degrees to 4 degrees over the next 40 years, causing stream flows to shrink as spring and summer become hotter, according to a study commissioned by the Colorado Water Conservation Board. "There have been a lot of reports out there, (but) this one really focuses on Colorado," said Jennifer Gimbel, director of the water conservation board.
Among the report's findings:
* Summers will become extremely hot, registering as warm or warmer than the hottest 10 percent of summers between 1950 and 1999.
* Little change in annual precipitation will occur, but temperature increases alone are expected to have a significant impact on snow and water supplies.
* Stream flows in the Colorado River Basin will shrink from 5 percent to 20 percent, exacerbating water shortages already forecast because of population growth.
* Spring runoff will arrive earlier, altering the times when farmers and utilities can expect their water to arrive.
* Summer water demand by homeowners will rise because of temperature increases.
* Despite warmer winters, temperatures above 8,000 feet will remain well below freezing, helping preserve snowpack and mountain environments.
The report was compiled by the University of Colorado Western Water Assessment, a partnership between the university, the National Oceanic and Atmospheric Administration, the CU Cooperative Institute for Research into Environmental Sciences and the Colorado Climate Center at Colorado State University...
"We need to be very careful about how we use our remaining Colorado River allocation," [Brad Udall director of the Western Water Assessment] said. "That water is a moving target under climate change. We don't know how much of it there is or how consistently we can expect it to be there." As a result, he said, Colorado needs to ensure it can keep enough water in the bank - Lake Powell - so that it can meet its obligations to downstream states while protecting Colorado's portion. Whether that means Colorado needs to build a major new reservoir in the state isn't clear yet, Udall said.
