Time and again over the last 15 years, Laura Norman, a research scientist with the U.S. Geological Survey, has seen evidence that when these structures — which Norman calls Natural Infrastructure in Dryland Streams, or NIDS — are placed in gullies, they slow water to mitigate erosion, collect nutrient-rich sediment and plant debris that nourish both crops and wild plants, help store carbon, improve groundwater recharge, and increase downstream water availability by as much as 28 percent. “It’s a snowball effect that counters degradation, and you get all of these ecosystem services,” she says.

The structures on Nutlouis’s farm are integral cogs in a larger system of floodplain farming. It works like this: Nutlouis’s property lies in an alluvial fan, where mineral-rich sediments and plant waste atop mesas and other uplands wash down onto flatter ground with rainwater, snowmelt, and spring water. Across the valley, similar farms rely on this kind of system, many of which feature stone and stick constructions that Nutlouis helped build. The organic materials trapped behind the structures, says Jonathan Sandor, an emeritus agronomy professor at Iowa State University, “are a major input into keeping the fertility of the soils up.” Such small watersheds are optimal: “These gentle slopes and small watersheds allow runoff but reduce the possibility of high runoff velocities that may damage crops,” Sandor explained in a 2008 paper.