Do you know of a statistic or set of statistics that says that, equalized I guess for climate and crop type, California agriculture uses water more efficiently than anywhere else in the world?Note that water is only one input of many (labor, capital, seeds, etc.), so I'd expect that water-use efficiency will be low in places where water is cheap (Imperial Valley) and high where it's expensive (Israel). California ag will only improve water efficiency efficient when water is expensive, and ag water prices will rise when farmers are selling water to urban and environmental buyers.
I could swear that I've seen something like that somewhere.
It tends to deflate the enviro crusade a little, I think, if it's true, because it shows that (assuming demand is constant) California may in fact be the best place to grow the water-intensive crops, and not vice-versa.
Bottom Line: When water is scarce (and price reflects scarcity), we will be more efficient in the ways we use it.