Although that has more to do with Seattle's aggressive environmental policy than supply of water.
It's actually kind of funny: when they first raised the price of water in Seattle, people cut back their water usage so much that revenue fell... so they had to raise prices more!
Schemes to bring water from the Columbia river are floated periodically but it would require political will across California, Oregon and Washington state, as well as approval from Canada, since Canada shares the river waters by treaty with the US. It takes too many stars to line up just right for it to be politically feasible, even though as an infrastructure project it could work.
"A widespread lack of snowfall this season has left Washington state in a deepening drought, and the prospects are grim: threats to crops and fish and increasing worries about wildfires."
a) they're also experiencing less water
b) it'd be crazy expensive... like billions and billions and billions.
c) they don't necessarily have all this extra water to feed the nation with
