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Lake Oroville's Dam Is Holding for Now
More Rain on the Way


Oroville Dam, located in the Sierra Nevada foothills, is the tallest dam in the U.S. and serves to impound Lake Oroville, the second-largest manmade lake in California. This is the first time the emergency spillway has been used since the dam's completion in 1967.

The danger of a massive flood downstream from California's Lake Oroville seems to have been averted for the time being as water levels dropped, stopping water from spilling over the dam's emergency spillway that officials said was in threat of failing from erosion.

"Failure of the emergency spillway was imminent, that's what they told us," says Susan Sims, a master arborist who lives in the area about 150 miles northeast of San Francisco.

This potential peril motivated authorities to order the evacuation of about 188,000 residents of Yuba, Sutter and Butte counties living below the lake where authorities said a 30-foot wall of water could descend upon them if the spillway failed.

The main concrete spillway had been damaged earlier, creating a 200-foot-long, 30-foot-deep hole so water was diverted from it and started flowing over the emergency earthen spillway. The Associated Press reported that erosion at the head of this spillway "threatens to undermine the concrete weir."

Officials are hopeful though since water is now flowing into the lake at about 45,000 cubic feet per second and flowing out at 100,000 cubic feet per second.

"They have gotten at least three feet of water out and stopped it from flowing down the emergency overflow and now it's flowing over the damaged regular overflow," says Sims, who is not in the evacuation zone. "They are trying to get things fixed up before the next seven days of rain."

Sims and her husband Gary own Sims Tree Health Specialists Inc., the Tree Learning Center, a 6-acre arboretum located in Jurupa Valley in Southern California, and a home and separate olive orchard in Butte County. The couple is allowing a friend and his family who had to evacuate to stay on their property.

"As far as I understand they are not allowing people back in yet," she says. "They are trying to fix things but then again, we have seven more days of rain coming in Wednesday."

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December 11, 2018, 2:05 am PST

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