There's not enough time and money to build a Great Lakes pipeline; nor will there be enough water in the Great Lakes to sustain Lake Mead (Colorado River System). If the climate coin flips the wrong way - there's an estimated 50% chance that "live storage" in the major reservoirs will be gone inside of 14 years, as discussed in the following abstract - those with enough money will be moving to Minnesota, Wisconsin, Michigan, etc. And poor Mexico...
See also::Jeremy's coverage of this in "Las Vegas Strip Could Run Dry by 2021" AND for further background see Tim's "Water Weirding: American Southwest on Uncertain Ground" AND for some good news see " Upper Colorado River Basin Flows Projected Best In A Decade"
Abstract of the paper "When will Lake Mead go dry?" follows:
 A water budget analysis shows that under current conditions there is a 10% chance that live storage in Lakes Mead and Powell will be gone by about 2013 and a 50% chance that it will be gone by 2021 if no changes in water allocation from the Colorado River system are made. This startling result is driven by climate change associated with global warming, the effects of natural climate variability, and the current operating status of the reservoir system. Minimum power pool levels in both Lake Mead and Lake Powell will be reached under current conditions by 2017 with 50% probability. While these dates are subject to some uncertainty, they all point to a major and immediate water supply problem on the Colorado system. The solutions to this water shortage problem must be time-dependent to match the time-varying, human-induced decreases in future river flow.
Tim P. Barnett1 and David W. Pierce1 Received 27 November 2007; revised 22 January 2008; accepted 5 February 2008; published 29 March 2008.
Wondering what happens to the coal fired generation capacities that have to be abandoned in the worst-case scenario (50% chance)?
Via::: Barnett, T. P., and D. W. Pierce (2008), When will Lake Mead go dry?, Water Resources. Research., 44, W03201, doi:10.1029/2007WR006704. By subscription.