Lake mead is down around 120 feet since its most recent high around 2000. The trend is looking very bad for this water resevior especially given the long term forcast related to climate change of drier conditions for the south west. A good graph showing the history of Lake Mead's water level is at:
http://www.arachnoid.com/NaturalResources/
I also read another report recenty which said that one of the main intake pipes that draws around 40% of the water supply for Las Vegas from Lake Mead will be out of the water in the next year or two given the rate that Lake Mead is dropping. They are now working on plans to extend this intake into deeper water. Its also projected that Lake Mead may be functionally empty by as early as 2021 in regards to electric power production and the lake levels being below the Hoover Dams outlets.