For years, the Prairie Pothole Region has bothered me in a very specific way. On a map, it looks like a normal landscape: fields, gentle slopes, small streams. But hydrologically, it behaves like something else entirely. The surface is peppered with countless depressions—wetlands and "potholes"—that can store water for days, months, or even years. Most of the time, rainfall and snowmelt do not move cleanly downhill into channels. They disappear into storage. Then, sometimes, they don't.