Heavy monsoon rains have helped to relieve the Southwest’s historic drought, but water officials say the deluge isn’t enough to reverse a drying trend that has depleted the region’s primary water sources.

Much of the West remains entrenched in a 23-year “historically unprecedented” drought driven by climate change, said Jonathan Deason, an environmental engineering professor at George Washington University.

“It’s going to take about three years of above-average rainfall to have substantial recovery,” he said.