Most of the time, the researchers found, the utilities fell back on carbon-emitting sources like natural gas and coal to fill their power needs. It’s not ideal, but it makes sense, says Amir AghaKouchak, a civil and environmental engineer at the University of California, Irvine. “Under drought conditions, the priority is to use water for people and cities, and managers might prefer to burn gas for energy,” he says. “Because you have alternatives for getting energy from different sources—but you don't have alternatives for water.”