It's pretty much impossible. Houston gets more rain than Seattle most years, but it's nearly impossible to pump that water up 500ft and 500 miles west to ranches in Texas. A pipeline from the Great Lakes or South East would have to pump water through the Rockies. They can't even build pil and gas pipelines to connect the West Coast to the rest of country, which is worth infinitly more per gallon than water.

On top of that, we have has abysmal rainfall this summer along the Great Lakes. I live on a river that flows into Lake Erie's western basin and i have never seen the river this low. There are stretches of the rover where i can walk bank to bank without getting my feet wet right now.