Los Angeles needed water, and lots of it. It still does. And that water comes from the LA Aqueduct, masterplanned by William Mulholland. The end of his career, though, wasn't such a triumph. This is the story of the St Francis Dam, and the collapse that stopped Los Angeles from taking over an entire valley. CORRECTION: It actually held back 47 million tonnes of water, 470 times more than I said. I mistook the dam volume for the reservoir volume when researching! Thanks to Josh for pointing that out.