IMO, California is single-handedly responsible for much of the dearth of water throughout the southeast US.
California worked fine with 10-15 million people, 20 million tops. All the infrastructure was built in the 40s to 60s for 20 million people. Now the state has 40 million.
It’s somewhat of a self-correcting problem because, the fine weather and scenery notwithstanding, it’s become a real sh!thole and people are leaving. They aren’t leaving fast enough, though. You just have to get 20 million to leave.
The recent droughts are so bad that I’m not sure California would work even with 20 million people.