When drought strikes, California farmers often pump water from underground aquifers to water their crops. But increasingly dry conditions are straining that resource. … [David Freyberg of Stanford University] says many people are looking at ways to replenish the state’s dwindling groundwater supplies. In California, a lot of water typically comes from winter snow that falls high in the mountains. During warmer months, that snow melts and trickles down to farmland. But as the climate warms, more precipitation is falling as rain instead of snow. So it rushes into rivers and runs past many areas where it’s needed.