The Dam tours were shut down due added security form the sept.11 attacks. You could still park and walk around the top of the Dam which is what I did. The Hoover Dam generates huge amounts of power which is  supplied to Vegas and Southern California.
Dam Movie

Panoramic Hoover Dam movie

Not sure what these strutures in the lake are for.

Large overflow drainage path goes around the dam

The road over the dam

Looking down at the generators

Lots power lines coming out the generators