It’s only May, and it’s already shaping up to be a stressful summer for many western states. Low mountain snowpack is a big part of the problem. Both the mighty Rio Grande and the Colorado River are experiencing low flow in places, prompting concerns about everything from water shortages to the plight of suffocating fish. U.S. officials have already launched rescue missions for an endangered minnow in New Mexico, where parts of the Rio Grande have already started to run dry—an unusual event so early in the season.