Spent plenty of time in the area to know it is a desert. They get their water from the Colorado River basin ~ and a little further North they can get water from the Aquaduct.
I even know personally the first regular employee of the California Water Authority (to wit, the Aquaduct) whose job was to run up and down a long segment and reset valves.
Just what is it you want to know about water in California ~ 'cause you sure don't sound like you have the slightest idea about it.
If you read my posts again, you will see that I was supporting your position.