USA city evacuated amid threat of dam collapse

Thousands of residents in northern California were asked to evacuate their homes on Sunday evening after the United States' tallest dam suffered damage posing threat of unleashing flood waters on towns just below it.

Officials said the 770 ft-tall dam could collapse at any moment, ordering everyone living in flood risk areas to leave immediately.

The Water Resources department said crews using helicopters would drop rocks to fill a gouge in the spillway.

DWR doubled the flow down its main spillway to avoid further erosion, increasing it from 55,000 cubic feet per second to 100,000.

Butte County Sheriff Kory Honea told reporters that a hole formed in an emergency spillway in the Oroville Dam, about 70 miles north of Sacramento.

EVACUATION CENTERS: An evacuation center has been set up at the Silver Dollar Fairgrounds and Neighborhood Church in Chico and the Glenn County Fairgrounds in Orland.

The water level in Lake Oroville rose significantly in recent weeks after a series of storms that dumped rain and snow across California, particularly in northern parts of the state.

Water started overflowing into the emergency spillway of Lake Oroville's dam in California on February 11. This is the first time in 50 years that water has come down the emergency spillway.

The water level dropped Monday behind the nation's tallest dam, reducing the risk of a catastrophic spillway collapse and easing fears that prompted the evacuation of almost 200,000 people downstream.

The Bush administration rejected that request, however, after the state Department of Water Resources, and the water agencies that would likely have had to pay the bill for the upgrades said they were unnecessary.

On Friday, officials warned that a 9-meter hole had appeared in a section of the dam and that water levels were less than two meters from the top. Its reservoir is the nation's second-biggest man-made lake.

Water was expected to continuing flowing over the emergency spillway for 38 to 56 hours, Mr See said on Saturday. Outflows remained high at almost 100,000 cubic feet per second.

While the dam itself is structurally sound, last week a hole caused by erosion was discovered on the main spillway. The flow over the emergency spillway began around 8 a.m. Saturday, according to a California Department of Water Resources press release. Also, as of now, the extent or severity of the "crevice" observed in the emergency spillway yesterday remains unclear, as the New York Times notes.

  • Larry Hoffman