Very interesting article. However, it only talks about drinking water and the real problem is water for agriculture and the author doesn’t talk much about cost of desalinated water vs cost of acquirer water. My own professional experience suggests desal water is cost-effective within sophisticated fertigation, controlled-environment systems which produce high value crops, but probably not for the more expansive wheat, maize, rice systems we use to grow our staples and animal feeds. Maybe we’ll be able to achieve this in an era of renewables.

Wouldn't it be easier to take the farms to where the water is, rather than bring the water here?

The grandfathering of water use rights from 100 years ago and the political clout of rural areas guaranteed by the typical state/federal senate apportioning makes this extremely difficult to turn around from having the farms in the desert in California and Arizona. How do we fix that?

Farms need a lot more than water, though. They need square footage, soil quality, suitable climate, access to infrastructure for shipping, and a good amount of cheap labor. All of those (except, increasingly, cheap labor) can be found in California.