I was surprised to read about how important agriculture is to California, and how thirsty the industry is:
California is known globally for its coastal beaches, mountains, and desert. But the state's most important economic region may be its Central Valley, one of the world's most productive agricultural areas. Virtually all of the almonds, artichokes, lemons, pistachios, and processed tomatoes grown in the United States originate from the valley, whose productive soil is unmatched elsewhere in the country. California's spinach yield, for example is 60 percent more per acre than in the rest of the United States. The state's marine climate allows it to grow crops like broccoli that wilt in humid climates.
California is the world's fifth-largest supplier of food, a big reason why the state would, if an independent country, be the 7th largest economy in the world.
But California's agricultural output demands a lot of water. Irrigation claims up to 41 percent of the state's water supply, while cities such as Los Angeles and San Francisco demand comparatively little. Crops such as almonds, grown exclusively in California in the United States, consume 600 gallons of water per pound of nuts, more than 25 times the water needed per pound of tomato. These water-intensive crops tend to have high profit margins, providing farmers with an incentive to plant them.