[throwaway342526]

" However, we would have to worry about food supply issues nationally and economic issues in what is already one of the most economically depressed areas of the country."

The impact would be relatively minor. For example, we could simply stop growing rice in the desert and more than recover all water saved by urban use: http://www.kevinroderick.com/rice.html

There's more water lost to evaporation in rice fields than LA uses in its entirety all year long. We could very easily move California rice production to wet areas in the south which don't suffer droughts and which already produce most of our rice: http://en.wikipedia.org/wiki/Rice_production_in_the_United_S...

[thrownaway2424]

The thing I say about rice is this: at least you can eat it. You can't say that about alfalfa, which uses over 5MAF of water per year (double the water input of rice) for negligible economic benefit (~a billion dollars in water needed to grow ~a billion dollars of alfalfa). This is chiefly used to feed cattle and more than 2/3rds of it is exported.