Mountainair, New Mexico, is not technically a desert. It averages nearly 15 inches (~40 cm) of precipitation a year. Nearly half of that falls in the summer rainy season, from late June into September, in big rapid thunderstorms.
With essentially no surface water for miles around, the ranchers dig stock tanks like this, carving out a depression along a drainage and piling up the dirt they remove into a berm that serves as a dam to hold back runoff for the cattle to drink. We saw this one on a drive Friday with Mom and Dad between Mountainair and Gran Quivira.