Desalination can provide for a lot more, even then, consumer usage is nothing compared to agricultural and industrial use.
We need a national water grid ASAP, before climate change threatens the food security of the US.
That would result in the export and subsidizing of the wasteful water management practices of the west. We could then look forward to a few years of record crops, then no crops as all the water runs out across the grid at the same time.
The pragmatic approach would simply be to price water so farmers and consumers are incentivized to use it efficiently.
People growing almonds with flood irrigation (and similar high water needy things) in cali or az
almonds, pistachios, sugar beets.. these (and others) are taking a toll on california's environment to produce some luxury goods for profit - not to provide food for the starving.
And almonds are hardly any more of a luxury food than a 20 minute shower or front lawn. Look at residential water consumption; how much really goes to basic living vs wasted? And how much effort goes into conserving or reusing water efficiently?
The point is to price water any let it flow to the most efficient use as determined by the market. When that happens, you’ll find that suddenly farmers stop flooding fields to grow alfalfa for Australian cattle and pick crops that are economically viable with the water constraints we have. Maybe nuts are too expensive to grow here; we don’t really know.