I think the idea is a huge waste, but the Utah State Legislature already considered exactly this in 2022 (building a massive pipeline to the Pacific Ocean).
https://www.sltrib.com/news/environment/2022/05/19/utah-legi... (archived non-paywall version: http://archive.today/GzuUD)
We really should just figure out how to be sustainable. I also think there is a hard reality people don't want to even consider talking about, which is the Southwest US is too overpopulated and overleveraged for the natural water resources available to it.
The southwest isn’t really over populated with people, it’s overpopulated with cows which require tremendous land and water resources.