The drought is going to start pinching farms in one year. This thread is about whether the California government should start rationing water now.

It's not that simple. Farm crops are what works well for the soil and climate of that region. You don't see fields of corn in California because it's not an attractive climate for corn. Likewise, you don't see fields of broccoli in Iowa, for the same reasons.

Midwest corn mostly goes to feed for cattle, hogs, and chickens. The corn may not be really great human food, but it gets made into great human food through an extra process step.

Migrant workers will move a lot more easily than a whole agricultual and peripheral industries. They aren't going to willingly abandon productive land in California so long as no one forces them to stop sucking water out of the ground. If water rights laws are abrogated toward the approximate reality that everyone owns that water, and only a fraction can properly be removed such that this maintaining the productivity of California agricultural land is non-competitive compared to other areas of the country, that'd be the free-market solution. But that implodes both the tax and voter based in California, so the incentive now is that the politics will dictate the continued legislated alternative to a market solution. Both the politicians favor this as does the agricultural business interests. Imagine some 35% of California farmland being made fallow, how does California replace that tax base? One of the reasons why it's such a rich state is because of its massive agriculture. Just in wine alone it'd be like saying, OK France can't grow grapes anymore. No matter whether you go with a market solution, a legislated solution, or a hybrid solution, it's all just plain icky. The technical solution is how to cheapen desalination such that it keeps California sufficiently competitive, i.e. things get more expensive but not untenably so.