California dam erosion not as bad as believed
Oroville, Calif. — Butte County Sheriff Koney Honea says engineers with the California Department of Water Resources informed him shortly after 6 p.m. that the erosion on the emergency spillway at the Oroville Dam is not advancing as fast as they thought.
Honea says two inches of water is still coming over the dam, but that is significantly down from earlier flows.
Honea says there is a plan to plug the hole by using helicopters to drop rocks into the crevasse.
He says the evacuation order went out after engineers spotted a hole that was eroding back toward the top of the spillway.
Honea adds authorities wanted to get people moving quickly to save lives in case “the worst-case scenario came into fruition.”
California officials say the cities of Gridley, Live Oak, Nicolaus, Yuba City and communities near Feathers River have been added to the evacuation order.
Hundreds of cars in wall-to-wall traffic can be seen on Highway 99 as people stream out of Oroville away from the dam.
Water began flowing over the emergency spillway at the Oroville Dam in Northern California on Saturday for the first time in its nearly 50-year history after heavy rainfall.
Unexpected erosion chewed through the main spillway earlier this week, sending chunks of concrete flying and creating a 200-foot-long, 30-foot-deep hole that continues growing.
Engineers don’t know what caused the cave-in, but Chris Orrock, a spokesman for the state Department of Water Resources, said it appears the dam’s main spillway has stopped crumbling even though it’s being used for water releases.
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.
The lake is a central piece of California’s government-run water delivery network, supplying water for agriculture in the Central Valley and residents and businesses in Southern California.