Photo: arbyreed

A couple scientists from the Scripps Institute released a paper about a month ago that puts even money on Lake Mead being dry by 2021. Just as bad, really, is that they also put a 50% chance that by 2017 the lake will be too low for the Hoover Dam to generate power. The authors give three main reasons: drought, water demand/use, and human-induced climate change.

Apparently Lake Mead is currently at so low a point (around 50% of its capacity) that the main water supply 'tube' for Las Vegas is in danger of rising above the surface. The Hoover Dam generates around 2 gigawatts of electricity and serves about 1.3 million people - not sure how it would be replaced if that generating capacity were lost.