Update: A mandatory evacuation affecting nearly 200,000 people around Lake Oroville in California was downgraded to an evacuation warning Tuesday — with the caution that the condition of the dam that imperils the area could still change quickly.

Butte County Sheriff Kory Honea said told the tens of thousands who were forced to leave their homes were free to return, but he urged them “to remain vigilant and prepared as conditions can rapidly change.”

An evacuation center at the Silver Dollar Fairgrounds will remain open, but all other locations in the county will close, the sheriff’s office said.

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Live feed here. Plenty of rumors, stay alert.

“The Oroville Dam’s auxiliary spillway has failed, forcing the evacuations of several counties in California, with between 60,000 and 100,000 people forced to evacuate from Butte, County, Calif., alone. ”

Msn, NBC 

Some official news sources seem to have it wrong. As of 8:25 pm, a relative of mine who was evacuated says the emergency spillway hasn’t really failed completely. It was never expected to be needed, so it was never tested, I was told. 

Yuba City, population 65,000, is the biggest city evacuated. The city has the largest dried-fruit processing plant in the world and one of the largest populations of Sikhs outside of India.

Photos


The gas lines were crazy and somebody said there was a fistfight over gasoline in one place.

Oroville Dam is an earthfill embankment dam on the Feather River east of the city of Oroville, California in the United States. At 770 feet (230 m) high, it is the tallest dam in the U.S. and serves mainly for water supply, hydroelectricity generation and flood control. 

Snapshot of traffic problems around 8:25 pm:


The California Department of Water Resources issued a sudden evacuation order shortly before 5 p.m. Sunday for residents near the Oroville Dam in northern California, warning that the dam’s emergency spillway would fail in the next 60 minutes.

The Oroville Dam is the highest in the nation.

An emergency alert issued on Facebook stated:

EMERGENCY EVACUATION ORDER ISSUED: Officials are anticipating a failure of the Auxiliary Spillway at Oroville Dam within the next 60 minutes. Residents of Oroville should evacuate in a northward direction, toward Chico. Other cities should follow the orders of their local law enforcement.

The emergency spillway, which is unpaved, was activated on Saturday morning to relieve the flow down the dam’s normal spillway, where a major hole appeared in recent days and began to widen. The height of the lake, once drained by drought and now swollen by recent rains and snow melt, had reached 901 feet above sea level when the emergency spillway was opened.

The dam impounds the 2nd largest man-made lake in California.

Officials feared a failure of the emergency spillway could cause huge amounts of water to flow into the Feather River, which runs through downtown Oroville, and other waterways. The result could be flooding and levee failures for miles south of the dam, depending on how much water is released.

The videos also showed lines of cars getting out out of downtown Oroville. An evacuation center was set up at the Silver Dollar Fairgrounds in Chico. 

Diminished by years of drought conditions, the reservoir had become a symbol of the state’s worsening water crisis. But an unusually wet winter took the lake from nearly full to overflowing in less than a week.

At the same time, the nearly mile-long concrete spillway that the dam’s managers rely on to release excess water began to crumble, with erosion worsening as millions of gallons of water poured over it.

It continued to rain. Realizing the lake might rise to a level that would trigger the use of an emergency spillway, state workers began clearing the area of trees and brush that could be sent hurtling downstream.

On Saturday morning, water began washing over the dam’s emergency spillway for the first time since it was completed in 1968. Photographs showed a torrent of water rushing downhill to join the Feather River.

… Officials emphasized that while erosion had carved a massive hole in the main spillway, the dam itself is structurally sound.

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… residents of Oroville, a town of 16,000 people, should head north toward Chico and that other cities should follow orders from their local law enforcement agencies.

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The emergency spillway partial failure was caused by just too much rain over too short a time, not by… Godzilla!