As state officials clamp down on records at Oroville Dam, one of the country’s foremost experts on catastrophic engineering failures has used state inspection reports, photographs and historical design specifications to piece together an autopsy detailing why the spillway at the country’s tallest dam failed so spectacularly this winter. The independent analysis by Robert Bea, of the Center for Catastrophic Risk Management at UC Berkeley, points to design and construction flaws dating back to the spillway’s construction in the 1960s.