Only about 30 -45 minutes from Vegas, just depends on where you're starting from.
Check out some of the places to pull over on the way to the dam, such as the overlooks. Some great photo opportunities.
$10 to park in their parking garage, after that you can do the self guided tour if you like, no charge. There are also a number of paid tours available.
My third trip here, and it is always impressive!.
Seems like the lake level is even lower than it was 6 years ago. Level is 155.81 feet below full pool of 1,229.00 as of 6-6-2016. White ring on the rock walls indicates where water would be if the lake was full.
On one side of the dam you are in Nevada, the other side in Arizona.
Gotta go at least once!