Lake Mead, on the border between Nevada and Arizona, USA, is the main water provider for Las Vegas, a city of 2 million people, in the middle of the southern Nevada desert. A colour shift in the rocks (visible) indicates the water drop the lake has witnessed in recent years. Lake Mead is 180 km long, and when filled to capacity, can reach 28 million acre-feet of water. However, the lake has not reached this capacity in more than a decade, due to increasing droughts.
{}