According to a piece in the Washington Post, "... across California’s vital agricultural belt, nervousness over the state’s epic drought has given way to alarm. Streams and lakes have long since shriveled up in many parts of the state, and now the aquifers — always a backup source during the region’s periodic droughts — are being pumped away at rates that scientists say are both historic and unsustainable."
38 million people, 27 million cultivated acres, CA grows more than half the country's fruits, veg and nuts.