I have a photo of one of the towers and it looks like there is some kind of panel that is covering one of the inlets.
It is near the top but maybe it gets lowered down.
Could be the "concrete log" that you suggested.
It's fun trying to figure this stuff out, especially since USBR is certainly...
Oh I'm quite certain photos like that are sensitive, although I don't know how anyone would get down into one of those towers.
It's a shame the tour is no more because just about every nook and cranny of the Dam is accessible.
What did you see on the insiders tour?
RC
I visited Hoover dam recently and was very disappointed.
I intended on taking the "hardhat" tour, which is more extensive than the normal tour.
Since 9/11, however, even the normal tour is no longer offered. You get a bird's eye view of one side of the Generators for a few minutes and that is...