From The New Yorker – Every Delta-related water issue has been complicated by the ongoing Western drought. (Tree-ring analysis shows the past two decades were the driest in more than a thousand years.) Under ideal circumstances, surface water and groundwater are complementary resources: in dry years, increased groundwater pumping makes up for the lower surface flows, while in wet years heavy precipitation allows subterranean aquifers to recharge. But the drought has changed all that, by stressing all resources at once. It has also hugely increased the challenge of maintaining water quality in the Delta hub. As less water flows down the Sacramento from the north, controlling salinity inevitably requires reducing exports to farmers in the south. Those farmers, who are the biggest users of Delta water, feel forced, in turn, to pump more groundwater, which is rapidly becoming as scarce as snowpack in the mountains. (Parts of the San Joaquin Valley have sunk more than islands in the Delta.) Every problem makes every other problem worse. (more)