So... you think Utahns are simply going to stop farming and end up destitute? I'm not following. No, they'll keep turning the spigot on because they have kids to feed, they'll just be poorer.
If you want better water regulation in the Utah desert, the solution is better water regulation in the Utah desert and not a huge tax on trade.
And I'm just saying that there are no lemons here. Empoverishing Utah farmers does nothing to fix their aquifer, period. They'll just be forced into less lucrative crops, and potentially into techniques that are more short-term and less protective of long term resources like water. Look at aquifer management elsewhere in the world. Are the poor countries doing a better job? Exactly.
If you want better water regulation in the Utah desert, the solution is better water regulation in the Utah desert and not a huge tax on trade.