I have mixed feelings about Hoover Dam. It's incredible architecture, a feat of human ingenuity to tame a wild and uncooperative land. It was Hoover Dam that allowed the surrounding land to be fertile, that helped Las Vegas become the oasis that it is.
But it's not without harm. It created Lake Mead, a huge reservoir of water, behind the Dam. That has been great for watersports and recreation, with thousands of acres of calm water in the middle of a desert. Lake Mead is in trouble though - it's way below historic averages in water level. Over a decade of drought has exhausted the abundant supply of water, and the desert is reclaiming once fertile land.
Vegas demands an increasing amount of energy and water, and the region simply cannot support it. Visiting Hoover Dam hit me with this realization like a brick to my head. Humans can make nature work for them in the short term, but abuse it like it has been here, and nature has a tendency to bite you in the ass.