A long stretch of highway running between Los Angeles and San Francisco separates the dry hills to the west from the green plains of the San Joaquin Valley to the east, where much of America’s fruit, nuts and vegetables are grown. Every couple of miles billboards hint at the looming threat to the valley. “Is growing food a waste of water?” one billboard asks. Another simply says, “No Water, no Jobs”. In the San Joaquin Valley agriculture accounts for 18% of jobs and agriculture runs on water. Most of it comes from local rivers and rainfall, some is imported from the river deltas upstate, and the rest is pumped out of groundwater basins.