I hate to break it to you, but modern farming methods rely on irrigation, there are very very few places where natural rainfall can support modern farming techniques... The insanely high yields per acre are only possible with irrigation. Water table depletion isn't limited to one county in California... most of the farmland in the US is depleting their aquifers, at varying rates, but few are not being depleted.
I live and have lived in Iowa and Nebraska. That Red area is over the Ogalla Aquifer, and it is being pumped out so fast that there are earthquakes, and the table is dropping. The tan areas in Iowa are where you don’t see many pivots.
You made my point. That water is going away, and isn’t coming back.