When you say "exported" and "local" are you referring to California, or the United States?
States need to be responsible for different resources, but as a whole, the United States must be self sufficient. No reasonable geopolitical strategy would require importing vital resources like food and wter.
"Must be"? No. Perhaps it would be nice, but even that is questionable.
> No reasonable geopolitical strategy would require importing vital resources like food and wter.
"Only a Sith deals in absolutes." More to the point, a reasonable geopolitical strategy would do so if self-sufficiency was either unattainable, or merely had an opportunity costs that exceeded the strategic value. Anyhow, the US is a massive net food exporter; and if California cuts backs due to drought, that will make production elsewhere in the world -- including elsewhere in the US -- that would otherwise be economically marginal more viable. Even if self-sufficiency in food was essential, these cutbacks wouldn't threaten it.
Anyway, these cutbacks are because there literally isn't water in the systems in which they hold rights to deliver to senior rights holders, not because farmers (which don't account for all the affected senior rights holders) are being politically targeted. Even if food self-sufficiency was a geopolitical strategic necessity, and even if curtailment would impact it, you can't deliver water that doesn't exist.