Many people are surprised to find out that most of the water that fills Gross Reservoir comes from tributaries of the Colorado River on the western slopes of Colorado. Unrelenting drought and years of rising temperatures due to climate change are pushing the long-overallocated Colorado River into new territory, setting the stage for the largest mandatory water cutbacks to date.

The Colorado River’s flow has shrunk during one of the driest 22-year periods in centuries. Scientists say the West is experiencing a megadrought and one that’s worsened by humanity’s heating of the planet.

The drought over the past year has hit especially hard in the Colorado River watershed. Last spring and summer, months of extreme heat combined with the lack of monsoon rains baked the soils dry and shrank the amount of runoff, sapping the river and its tributaries. A year ago, about 4% of the West was in a severe drought. Now, about 58% of the West is classified as being in a severe, extreme or exceptional drought.  

This all speak to what a bad idea it is for Denver Water to try to pull more water out of the Colorado River system to fill an expanded Gross Reservoir! A good article by Ian James on what the southwest faces can be read at the Arizona Republic.