The American Southwest has horribly mismanaged it's fresh water supply. Tulare Lake, Hoover Dam, and Las Vegas are just some examples of the American Southwest's horrible fresh water management. My suggestion is does the rest of the United States and North America have a right to the fresh water contained in the Great Lakes? Would a pipeline from Chicago to Los Angeles or Mexico City be better for the environment than a desalination plant?
I think some folks has mentioned a few reasons why this specific plans is not too great, but there is some potential to the idea of a water distribution network in much the same way that high speed rail networks are pretty awesome outside the influence of capitalism
I've often wondered if it would make sense to create material corridors that would contain high speed rail, electricity grid and water pipelines. You could even add in some solar/renewable energy along the way. This would facilitate the shifting of resources in a kind of mutual aid at scale. Just one of those sci fi utopian concepts I contemplate to fall asleep.