It has nothing to do with the people. The majority of the water is used for agriculture, which supplies the nation and even the world with water-hungry food.
That is to say, we should be building desalination plants in California. Israel figured out a way to do this economically already. It's high time for CA to follow suit.
[1] https://www.sdcwa.org/your-water/local-water-supplies/seawat...
In other words: California does not value water equally between use cases -- to the point where certain crops are exploiting that imbalance. E.g. almonds might be a special case since, while water intensive, there may be fewer alternative geographies. Cattle, however, are plenty-viable elsewhere & shouldn't receive such an imbalanced incentive to consume water.
One natural starting point: One liter of water is priced uniformly regardless of use...
Before we have desalination, we need more renewable energy.
It kind of sounds like it has everything to do with people, unless people aren't eating that agriculture or eating whatever that agriculture eventually feeds.