Anybody knows that one waterfall attraction in the Southeast US? The one that advertises bloody everywhere? Waterfall is pumped during the dry seasons, otherwise there'd be nothing to see. Lots of the formations are fake, and the Cactus and Candle formation was either moved from a different spot in the cave, or is from a different cave in New Mexico. Management doesn't want people to know that, but fuck 'em.
After looking it up, you can find reports from others stating the same things. When I was there as a kid, I remember that they claimed no one knew where the source of the water came from... I guess they actually know enough to help it out at least, lol
I really enjoyed it and would like to go again, but it's no Mammoth Cave.
I mean, I'm sure humanity pumps that much water, in aggregate. If you look at every pumped system everywhere in the world, it's no doubt many times Niagara.
Now, doing it all in one place, like that? Yeah, for sure, that's tricky.