Since we seem to just be stuck suffering this regime of "water rights" as imaginary property... If these are true legal property interests can they not just be

Since we seem to just be stuck suffering this regime of "water rights" as imaginary property... If these are true legal property interests can they not just be sold/rented to other users? Even if the arrangement needed to remain contingent upon that amount water actually reaching a different user downstream to consider it being used, that would seem much better than the current approach of squandering it. Then we could at least apply market economics to the situation as the flow of water decreases. Just consider it a strategic sunk cost that Saudi Arabia or whomever has obtained a financial entitlement to most of the Colorado River (Saint Coase would be proud), and then move forward from there. I'd hate to see the imaginary property regime get any more entrenched, but it would seem better than the current impasse.