It's not just local beef production either—30% of the alfalfa and hay goes overseas, 20% to China. We're taking the tiny amount of water we have in this desert and shipping it over an ocean.
Not sure we want china firing freshwater ice at utah on a ballistic trajectory?
<this is a funny joke post don’t freak out man>
It's still a problem, but we need to keep in mind that maybe we shouldn't be farming so much animal feed in general. We'd still lose this water if we kept the feed local.
If you used a 1000000 kg of water to grow alfalfa, you'd get around 25000 kg of alfalfa (which would contain 5000 kg of water and 20000 kg of other stuff).
So for every 5000 kg of water that is in that alfalfa when shipped around 995000 kg of water stays.
30% looks reasonable to me. That is 70% are sold locally.
Does other water-using industries exports around the same percentage?
Alfalfa fed to local cows that are consumed locally keeps the water in our ecosystem, within the bounds of our natural water cycle. Alfalfa fed to cows overseas exports our water overseas, so it doesn't reenter the water cycle locally, and it may never find its way back (on human timescales).
You can think of it as having a trade deficit for water—we're not importing it in sufficient quantities to make up for our exports, and the result is that our local environment gradually dries out. Wetter climates don't have that problem because water that evaporates from the ocean can be treated as unlimited.
Edit: Clarified a few things.
The water doesn't physically go into the final shipped alfalfa in meaningful quantities. 99.9% of the water that is used in growing alfalfa evaporates, or ends up in the ground, and it doesn't matter whether the remaining 0.1% that actually ends up, and stays inside the plant gets exported to Mars, or consumed locally.
When growing alfalfa, 100 tonnes of water is used to produce ~300lb of biomass. When you're sourcing those 100 tonnes unsustainably, it really doesn't matter whether you export the 300lb, or not.
You're blaming a foreign boogieman for a domestic, self-inflicted problem.
My extended family are cattle ranchers in southern Utah, and a lot of alfalfa is grown to feed cattle in the winter. A lot of the weight of a bundle of alfalfa is water - probably most of it when freshly harvested. When processed, it's left to dry for a while, but the alfalfa that gets sold is probably still 10-20% water.
Our ranch doesn't sell the alfalfa we grow, but there are plenty of massive , industrial scale, operations near our ranch that exclusively sell alfalfa on foreign markets. At their scale, not shipping alfalfa overseas would make a meaningful dent in the problem. It wouldn't solve it entirely, but it would likely have a greater impact than people not washing their cars.
And for every liter of water that's left in dry alfalfa, it took ~4,000 liters of water to grow it.
You, like the parent poster, are making a huge mistake, in thinking that that one liter that's getting exported is at all a meaningful part of the water sustainability problem with going alfalfa in a desert. It's not. The unsustainable part of it is the other 3999 liters.
'Don't export alfalfa grown in a desert' optimizes the part that isn't important. 'Don't grow alfalfa in a desert' is what people actually need to be doing.
In my opinion, exporting any amount of water is too much.
Saying that doesn't mean I'm unaware of the other ways in which water could be better managed.
Alfa-alfa is grown here, packaged and shipped to Saudi-Arabia because it's cheaper this way than for Saudi-Arabia to desalinate water and grown their own stuff.
Yet my water bill is going up by 6%.