You make a very simple statement without any real justification: "We just need to stop growing such crops." I'm guessing that you have all sorts of justification for this and assume that those justifications are well-known and generally agreed. But for those of us less educated, what is the justification? Why shouldn't agriculture be given priority in these regions?
Why is water different than land in this regard? When a developer wants to put up a new subdivision, they buy property from the current owner. Why shouldn't water shares be the same?
If you eliminate 100% of suburban water use you will still have a water problem. If you want a land analogy, it would be like looking at people in San Jose and saying they're the reason for a lack of farmland in California.
Plentiful and subsidized year-around food is a security issue on the federal level - but when compared to other industries it brings in comparatively little for the states involved. You can't reasonably expect a few water starved states to export the majority of its water via crops while sacrificing its own economic prosperity for the sake of the broader country.
In Utah, 80% of water use goes to agriculture. And farmers pay about 1% of what residential customers pay for water.
As a nation, we have this fantasy of turning the desert green. The book Cadillac Desert lists our national obsession with massive water projects that never pay for themselves and that always require massive tax subsidies.
There are various measures of water usage for various crops. Commonly you have "water usage per kilogram of crops" and "acre feet of irrigation water per acre of farming land" but these aren't that useful (IMHO). A far more useful measure if "water usage per kilocalorie" since that's really waht matters and this varies a ton from food source to food source [1].
The "use it or lose it" system of water rights for agriculture in the Colorado River basin creates warped incentives, which is to maximize water usage rather than the economic value of the crop or the calorie content of that crop.
It's clear we can use a ton less water and still feed people in a way that's economically viable for the farmers. But no one wants to give up the water because once it's gone, it's gone.
This situation has real impacts where some in California, for example, were floating the iea of using desalination to provide potable water for people rather than the far cheaper and more obvious solution of just using less water on water-intensive crops.
All of this is just superficial responsibility shifting.
Alfalfa and almonds are thirsty yet we grow them by the square mile in the desert. It doesn't take much googling to realize this is not a smart thing to do in a drought area.
I guess I don't google enough. I live in the middle of a desert. I live near a small stream in the middle of the desert. That small stream is dammed and diverted to irrigate, wait for it, alfalfa.
If we didn't grow alfalfa we would have a lot more water for people to drink. We could sustain more people. Then, instead of having a few thousand people live next to a little stream in the middle of the desert, we could have tens of thousands of people live next to a little stream in the middle of the desert.
No amount of googling explains to me why it is better to have more people near a small stream than it is to have more alfalfa near a small stream.
Imagine a small island that used the scarce land for agriculture. Would it be better to put more people on the island, or would it be better to grow food on the island? What if there were only a few people and they had large fields to grow food. Should they be forced to give up their land so more people could live on the island?
Why is it so important to fill the island with people?
Why is water different than land in this regard? When a developer wants to put up a new subdivision, they buy property from the current owner. Why shouldn't water shares be the same?