The majority of water in Santa Barbara is derived from local sources. While there is a lot of local agriculture, it is primarily on coastal planes, not in classic desert areas like Imperial Country. In our current year we've had less than half our typical rainfall, and it has has been going on like this for three years now. Our last drought, when the desal plant was first built, took seven years to set in, we've reached the crisis point in this drought much more quickly. My point is I don't think we're quite as dumb as the rest of the state where they can't ever manage on local sources in normal years, we can. But when things go dry quickly like they have, we get caught out.
Of course building a desal plant in an emergency is actually a rain dance. It worked perfectly last time, and given the predictions of an El Nino for next year, it should work this time as well.