Um, there is some truth to this.
I don't know all of the details, but the main freeway between Sacramento / San Fran and Southern California is I-5, which is mostly farm land. There are signs all along the freeway that say something like "no water, no farms". I forget exactly what they say, but I remember seeing them last time and I looked it up when I got home. But it's something about how the government has diverted water from that area to some place else, fucking up the farms in the area.
A quick search turned up this:
http://www.farmwater.org/
(Not that I give a fuck what Glen Beck says.)