Capitalism is an absolutely zero-sum game. The best case scenario for the land owners is they get bought out by the government, and maybe they get off okay if they're given a decent price. But at least some of them just aren't going to get the water they need to operate their farms, which makes that land utterly worthless. All the value just gone. And unless the feds pony up some very attractive buy-outs no one has any incentive what so ever to be the one who makes a sacrifice. It's a war of all against all.

And of course regardless of who does and does not get water all kinds of small towns, small operations, and lots and lots of workers are going to get totally, utterly fucked and thrown out into the streets of LA or Vegas.