It is a telling illustration of the precarious state of United States dams that the near-collapse in February 2017 of Oroville Dam, the nation’s tallest, occurred in California, considered one of the nation’s leading states in dam safety management.

The Oroville incident forced the evacuation of nearly 190,000 people and cost the state $1.1 billion in repairs. It took its place as a seminal event in the history of US dam safety, ranking just below the failures in the 1970s of two dams—Teton Dam in Idaho and Kelly Barnes in Georgia—that killed 14 and 39 people, respectively, and ushered in the modern dam safety era.