California’s Tulare Lake was once the largest body of freshwater west of the Mississippi River. Located at the southern tip of the San Joaquin Valley, it collected snowmelt from dozens of Sierra Nevada streams. Today, the giant lake is long gone: In the decades after the Gold Rush, it was drained and transformed into farmland. Now, in a modern era of water scarcity, some are eager to see even a small bit of the old Tulare Lake restored. It could be an effective way to recharge groundwater that’s been overtapped by those same farms.