Cloud seeding is a geoengineering technique that involves using planes and cannons that shoot silver iodide into clouds, causing a reaction that makes storm clouds create 5 to 15 percent more precipitation. Utah and Colorado have been cloud seeding in the Upper Colorado River Basin for decades, spending between $1 and $1.5 million each year, and New Mexico recently began approving cloud seeding permits.

Frank McDonough, a scientist at the nonprofit Desert Research Institute, tells AP that “the research that’s come out over the last 10 years or so really seems to have convinced [states] that cloud seeding is a legitimate way to increase snowpack and subsequent water resources.” The federal funding comes at a critical time as the Colorado River basin’s key reservoirs reach record lows, and Western cities and industries struggle to conserve water even as supplies continue to shrink. (AP, Explainer: Yale Environment 360)