CA, apparently, grows almonds for the entire United States, and 80% of the world's almonds, too.
Is it economically important? For sure.
Is it critical for living? No.
Agricultural users should be free to pay market rates for their water like everyone else. They will absolutely still be able to make a profit growing almonds since they basically own the market.
The problem, as others said, is that their cost is artificially low as they don't pay market rate for water.