Data from NASA satellites show that the total amount of water stored in the Sacramento and San Joaquin river basins — that is, all of the snow, river and reservoir water, water in soils and groundwater combined — was 34 million acre-feet below normal in 2014. That loss is nearly 1.5 times the capacity of Lake Mead, America's largest reservoir. Statewide, we've been dropping more than 12 million acre-feet of total water yearly since 2011. Roughly two-thirds of these losses are attributable to groundwater pumping for agricultural irrigation in the Central Valley. Farmers have little choice but to pump more groundwater during droughts, especially when their surface water allocations have been slashed 80% to 100%.