In 2007, the seven states that rely on the Colorado River for water reached an agreement on a plan to minimize the water shortages plaguing the basin. Drought had gripped the region since 1999 and could soon threaten Lake Powell and Lake Mead, the largest reservoirs in the nation.

Now, that future has come to pass and the states are again attempting to reach an agreement. The Colorado River faces a crisis brought on by more than 20 years of drought, decades of overallocation and the increasing challenge of climate change, and Lake Mead and Lake Powell, its largest reservoirs, have fallen so low that their ability to provide water and generate electricity in the Southwest is at risk. But reaching consensus on how to avoid that is proving to be more challenging than last time.

“The magnitude of the problem is so much bigger this time, and it’s also so much more immediate,” said Elizabeth Koebele, an associate professor of political science at the University of Nevada, Reno.