Tallest US dam spillway threatens collapse, 130,000 urged to evacuate in California

OROVILLE, California (AP):
Thousands evacuated their Northern California homes Sunday evening after US authorities warned an emergency spillway in the country's tallest dam was in danger of failing and unleashing uncontrolled flood waters on towns below.

About 150 miles northeast of San Francisco, Lake Oroville is one of California's largest man-made lakes, and the 770-foot-tall Oroville Dam is the nation's tallest.

At least 130,000 people were asked to evacuate over concerns the dam's emergency spillway could fail. Hundreds of cars were in bumper-to-bumper traffic on highways and at least two shelters said they were at capacity.

The erosion at the head of the emergency spillway threatens to undermine the concrete weir and allow large, uncontrolled releases of water from Lake Oroville, the California Department of Water Resources said. Those potential flows could overwhelm the Feather River and other downstream waterways, channels and levees.

Officials say Oroville Lake levels had decreased by Sunday night as they let water flow from its heavily damaged main spillway but noted that water was still spilling over the dam.