When a prairie river carries more water in one year than another, the obvious place to look for an explanation is the sky. A year with more snow and rain should have more water in rivers. That was also how I initially thought about year-to-year changes in river flow. But while studying the Prairie Pothole Region, I learned that this is only part of the story. What happens after water reaches the ground can be just as important as how much falls from the sky.
