Hint: pass up that $7 parking lot that looks curiously empty - there's other free lots just past it!
I know, I know, it's HOT. And the sun is beating down, and that $7 lot lets you park under a cover. I swear, the other lots aren't that far beyond!
The dam itself is amazing to see, as is the brand new bridge. I think you can even go on tours of the inside of the dam (where it may be air conditioned, I hope!), but I'm not sure how to schedule it.