You would play hell getting the water away from us here in the great lakes states anyway. Despite the belief that lefties would oppose, I suspect it would be a near unanimous “Hell no”.
The lakes are extremely valuable right where they are. The great lakes sportfishing industry is a $10 billion industry in Michigan alone. Tourism and other watersports are big as well. Also the great lakes create the ideal climate for certain major crops.
Besides, only an idiot would pump water 2/3s of the way across the continent, over a couple of mountain ranges only to dump it on the ground next to an ocean.