Oroville Dam Spillway Built on Crumbling Rock, Warned Contractor That Built It

An investigation into last winter’s near catastrophe at Oroville Dam uncovered a litany of problems with how the dam was built and maintained, but one of them stands out: Even as workers built the dam, they were raising alarms about the eroded, crumbling rock on which they were directed to lay concrete for the 3,000-foot-long main flood control spillway.