Monday, February 13, 2017
Associated Press
OROVILLE, CALIF.
Thousands evacuated their Northern California homes Sunday evening after authorities warned an emergency spillway in the country’s tallest dam was in danger of failing and unleashing uncontrolled floodwaters on towns below.
Hundreds of cars were in bumper-to-bumper traffic on Highway 99 as people hurried away from the Oroville Dam.
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 capacity of downstream channels and levees.
Butte County Sheriff Koney Honea said engineers with the Department of Water Resources informed him shortly after 9 p.m. that the erosion on the emergency spillway at the Oroville Dam was not advancing as fast as they thought. Two inches of water were still coming over the dam but that was significantly down from earlier flows, he said.
The evacuation order went out at 7 p.m. to at least 130,000 people after engineers spotted a hole that was eroding back toward the top of the spillway.
Honea said there is a plan to plug the hole by using helicopters to drop rocks into the crevasse.
Water began flowing over the emergency spillway at the Oroville Dam on Saturday for the first time in its nearly 50-year history after heavy rainfall. Officials earlier Sunday stressed the dam itself was structurally sound and said there was no threat to the public.