"Disaster appeared imminent at the nation's tallest dam on Sunday, Feb. 12, 2017.
A crater the size of a football field had sunk into the middle of the spillway at Oroville Dam in Northern California.
Dam operators shut off the water flowing down the spillway about 70 miles north of Sacramento. But the reservoir continued rising from recent storms, soon cresting an "emergency" spillway that was little more than a hillside and that quickly eroded.
Officials warned that the 770-foot-tall dam could unleash a 30-foot-tall torrent onto the communities downriver. The state ordered nearly 200,000 people to evacuate.
Catastrophe was averted. But the event awakened the public to the risks posed by the country's aging dam infrastructure."