Dry conditions are the worst they’ve been in almost 20 years across the Colorado River watershed, which acts as the drinking and irrigation water supply for 40 million people in the American Southwest.

As the latest round of federal forecasts for the river’s flow shows, it’s plausible, maybe even likely, that the situation could get much worse this year.

Understanding and explaining the depth of the dryness is up to climate scientists throughout the basin. We called several of them and asked for discrete numbers that capture the current state of the Colorado River basin.