The rain has started to return in Northern California and will continue over the next few days, but officials aren't as concerned about the upcoming weather so much as the damage already done to the Oroville Dam's already compromised main spillway.

The risk of flooding has dropped substantially, but Butte County Sheriff Kory Honea warned residents Wednesday that they remain in "an emergency situation."

Oroville Dam spillway expected to fail; residents ordered to evacuate

Water from Lake Oroville flows down a damaged main spillway. (Brian van der Brug/Los Angeles Times)
Water from Lake Oroville flows down a damaged main spillway. (Brian van der Brug/Los Angeles Times)

Residents of Oroville and nearby towns were ordered to immediately evacuate Sunday after a “hazardous situation” developed involving an emergency spillway at the Oroville Dam.

The National Weather Service said the auxiliary spillway at the Oroville Dam was expected to fail about 5:45 p.m., which could send an “uncontrolled release of flood waters from Lake Oroville.”

Those in Oroville, a city of about 16,000 people, were asked to flee northward toward Chico. In Yuba County, those in the valley areas were urged to take routes to the east, south or west.

“This is not a drill. This is not a drill. Repeat this is not a drill,” the National Weather Service said. Authorities urged residents to contact neighbors and family members and reach out to the elderly and assist them in evacuating.

The Butte County Sheriff’s Department and the state Department of Water Resources said the failure of the auxiliary spillway — a 1,700-foot-long hillside route — was caused by “severe erosion.”

The evacuations marked a dramatic turn of events at the nation’s tallest dam. For several days, officials have been trying to figure out how to get water out of Lake Oroville after the main spillway was damaged.

The emergency spillway had never been used before — and until the last few hours it seemed to be working well. But water from rain and snow continued to flow into Lake Oroville at a rapid pace, causing the water level to rise to emergency levels.

Lake Oroville is the linchpin of California’s state water movement system, sending water from the Sierra Nevada south to cities and farms.

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