In the weeks and months to come, investigators will no-doubt probe many potential reasons for the near-catastrophic failures at Oroville Dam in February. Those will range from decisions made more than 50 years ago, to the truly extraordinary weather of 2017. But for the moment, the emergency at Oroville Dam has largely passed. The 180,000 people who were evacuated from their homes last month have returned, and construction crews continue to put millions of tons of rocks and concrete across a badly eroded hillside under the emergency spillway.