The only permanent thing left behind is another environmental religion, the religion of endless drought. It's a political thing, not science. Now you have a drought lobby installed forever in Sacratomato funded to attack developers and farmers. That's all.
'Forever' is a very long time. Droughts come and go. California underwent a 200 year long drought nearly 1000 years ago. So it can get worse. Far worse. Fortunately, the Pacific ocean is very nearby. Desalinization means that we have access to water forever. That's right. Forever. But it won't be cheap.