Water used to grow almonds - 1.1 trillion gallons per year - is just about enough to provide water for around 23 million people in California (~59% of the population).
A $5-$6 billion crop, consuming half the residential water for a $2.7 trillion economy. If you include alfalfa, which is even worse than almonds, it's something comparable to 150% of all the residential water use in California.
It's a spectacular failure on the part of the state of California. Where are the famous CA voter propositions when you need them? A large share of the alfalfa and almonds - aka California's water - gets exported to Asia. It's social and economic suicide for meager benefits.