Paul Kehmeier is a fourth-generation farmer from western Colorado. One hundred and twenty years ago, his great grandfather Wilhelm Kehmeier bought land in Delta County, dug an irrigation ditch to bring water from a nearby stream, and got to work planting. The Kehmeier family has been farming on the same land ever since, growing alfalfa, hay and oats. But a few years ago, Paul Kehmeier did something unusual: he decided not to water about 60% of his fields.