What you say is true, right on the money. And there are pictures of low water in reservoirs.
But something else is involved as well, methinks.
Several other factors, so I can only guess what you mean. I'll skip divine punishment, because there are a lot of good folks in California living amongst the evil liberals.
One factor is population. Cramming millions of people into a desert area was not such a good idea, as water was already in short supply. And that's what large areas of Southern California are - desert areas. A huge influx of people over the last fifty years made a bad situation worse.
Another factor is politics. Liberal greenies are flushing millions of water away for the sake of their favorite tiny plants and fish, diverting the water away from where it is truly needed. It's a nice thought to restore wetlands and marshes to what they were 500 years ago, except for the fact that millions of people are here now and the greenies won't give consideration to the needs of those people.
So maybe divine intervention is how you remove millions of people to restore a balance. Cut off the tap and they'll leave?