This is a no brainer. A win win for everyone.
The North and East have an abundance of water. So much they have to design ways to get rid of it all. The West needs water.
We could open up dry desert land to farming. Increase our GNP. If we can pump oil from Canada to Texas ..... why can't we pump water to Texas, Oklahoma, Utah, Nevada, Arizona, California, and even sell some to Mexico.
We have the technology, resources, and the need.
If the Roman Empire could carve holes through mountains to bring water to the Empire ...... why is farm land drying up in California?