Alternative solutions have been proposed — like towing icebergs from the Arctic or diverting water from the Missouri River to use on the other side of the Rockies. But the standard response to scarcity — grabbing more — cannot work any longer. There isn’t more water to grab.

Yes there is... in Canada. Fresh water, oil and lots of brown people.. Saddle up, time to go a-liberatin!!!

Canada already sells us water and oil, right?

oil yes, but water, it seems not at any large scale:http://en.wikipedia.org/wiki/Water_export