The chances that the reservoirs fed by Colorado River water will dry up by 2050 are one-in-two if we don't change our water-management practices and if the climate keeps warming, according to a summary of a new University of Colorado report by LiveScience on MSNBC.com . An estimated 30 million people, most of them in Arizona and southern California, depend on the river for drinking water and irrigation at a time when the system is entering its 10th year of drought and populations are projected to keep growing. Still, the chances that reservoirs like lakes Mead and Powell would go bone dry are less than 10 percent, even in worst-case scenarios, writes the Denver Business Journal . Denver Water's director of planning, David Little, goes a step further, saying it is "not true" that the reservoirs could be depleted (via The Denver Post ). Little points to other research that shows upper parts of the Colorado River Basin could become wetter because of climate change. Nonetheless, he concedes, if giant reservoirs west of Colorado have less water, Denver could see its population rise more quickly than expected, as westerners head east, toward the water.