There is a debate growing in California about whether crops like almonds (that use a lot of water) should be allowed. But all that authoritarian command and control debate about "allowing" certain activities is unnecessary. Just raise prices to some sort of supply and demand matching level (it is a bit awkward to do this because there is not a true free market in water supply but any attempts have got to be better than the current absurdly low prices). Then the almond growers themselves, and the rice growers, and the golf courses, and everyone else will decide if they can still operate in CA or not. No politicians' commands necessary.
Raising prices also creates a secondary benefit over government-imposed rationing -- it provides incentives for people to seek out and invest in new sources of supply. Desalinization, any one?