The US has options, one of which is desalination. Australia has far fewer options.
And in the US, the economics of desalization versus import are going to be different in San Diego than they would be for Denver.
a lot of water from colorado ends up in Los angeles.
LA pays 450@acre foot for colorado river water. you can see that ribbon of blue cross from arizona to LA if you’ve ever flown over the area. Utah has already talked about building a desalination plant for LA and then taking LA’s water alotment. I don’t think the deal will be really compelling until the cost of desalinized water is less than 450@acre foot. That day is only a couple years away.