The idea that farmers' water rights are inalienable seems absurd to me. A state can be in a drought but farmers needn't curb their usage at all?
If each suburban plot of land in California hypothetically came with a guarantee of 100k gallons of water a month, there would be no doubt that this would be cut immediately when a drought hit. It's only farmers' lobbying power that stops their water rights from being restructured wholesale.
With that said, I do think agriculture rightfully gets a lot of water allocated. Much of it seems wasted, though.
The free market had its say when these water rights were sold, taking it back from them with eminent domain so we can charge more is not the free market.
I suggest you watch this very informative talk by the water board director to the MIT alumni club last year to help clarify your POV: http://m.youtube.com/watch?v=rShYQVZvX-k
http://www.cnbc.com/2015/05/28/west-coast-drought-why-califo...
Doesn't look like a free market to me.