Government issues emergency over "imminent" collapse of Oroville Dam’s spillway as thousands flee from their homes.
At least 130,000 people living below the tallest dam in the United States have been asked to evacuate as a spillway appeared in danger of imminent collapse.
The California Department of Water Resources said on Facebook at about 00:30 GMT on Monday that the spillway of California’s Oroville Dam was "predicted to fail within the next hour".
While it was still standing nearly three hours later, the Water Resources department said crews would use helicopters to drop rocks to fill a gouge in the spillway.
Authorities were also releasing water to lower the lake’s level.
Officials said the cities of Oroville, Gridley, Live Oak, Marysville, Wheat land, Yuba City, Plumas Lake, and Olivehurst were all under evacuation orders.
Aerial video shows strain on California’s Oroville Dam’s backup spillway hours before thousands ordered to evacuate.
Meanwhile, the Butte County sheriff said in a statement posted on social media: "Immediate evacuation from the low levels of Oroville and areas downstream is ordered, This is NOT A Drill."
Doug Carlson, a spokesman for the Department of Water Resources, said water levels on Friday were over 273 metres, less than 2 metres from the top.
Evacuation centers were set up at a fairgrounds in Chico, California, about 20 miles northwest of Oroville, but roads leading out of the area were jammed as residents sought to drive out of the flood zone.
The dam, which serves mainly for water supply, hydroelectricity generation and flood control, activated its emergency spillway after weeks of heavy rain caused the reservoir to rise above its capacity.
At 230 metres high, the structure, built between 1962 and 1968, is the tallest dam in the US, besting the famed Hoover Dam by more than 12 metres.