The West could be facing a water shortage in the Colorado River that threatens a century-old agreement between states that share the dwindling resource.
That possibility once felt far off, but could come earlier than expected. One prominent water and climate scientist is sounding the alarm that the Colorado River system could reach that crossroads in the next five years, possibly triggering an unpredictable chain-reaction of legal wrangling that could lead to some water users being cut off from the river.
Brad Udall, a senior water and climate scientist at Colorado State University’s Colorado Water Institute, sits by the Blue River in Silverthorne, which is filled with the snow and rain that falls in the Rocky Mountains of Colorado. Water from the Blue River feeds the Colorado River and the tens of millions of people who rely on it across seven western states, 30 Native American tribes and Mexico.
The flow of the Colorado River has dropped 20 percent since the 1900s. Roughly half of that decline is due to climate change, which has fueled a 20-year megadrought across Colorado and the West. That rapid decline could soon cause problems between the states that share this water, Udall said.
Udall said the deal contains a fatal flaw: fixed numbers, which were set when climate change wasn’t a concern.
“You can't have fixed numbers in a declining system,” Udall said. “That's going to unduly impose pain on [parties] that are completely undeserving and never signed up for that.”Part of that agreement requires states in the upper Colorado River basin — Colorado, Wyoming, Utah and New Mexico — to keep a certain amount of water in the river to ensure the flow reaches states in the lower basin, including Arizona, California and Nevada. That agreement was amended in the 1940s to ensure river water also reached Mexico.
If the river keeps drying up, that agreement could soon be broken. That could trigger a formal water delivery shortage and what’s known as a “compact call” for the first time. The result could mean upper-basin states, including Colorado, are forced to cut off some water users to make sure there is enough water in the river to flow downstream.
“That will be a day of reckoning for the upper basin,” Udall said.
Udall’s projections for the Colorado River aren’t a certainty, but if climate, drought and water conditions continue as expected over the next five years, the amount of water delivered from the upper-basin states could drop below the agreed-upon 10-year running average amount of about 8.2 million acre-feet per year for the first time.
