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Sheriff: This is not a drill: Evacuate Now! Largest dam in U.S. about to collapse

100,000 and more people are evacuated and on the search for shelter in California tonight. It’s a tourist attraction in California, and it’s turning into a possible life-threatening experience for visitors and locals alike at this moment. Oroville Dam is the tallest and the largest earthen dam in the United States.   Visitors can climb a 47-foot tower to view the lake and the Sutter Buttes.

America’s critical infrastructure: dams, bridges, & the grid is aging and woefully ignored.

The initial prediction held that the dam would fail within the hour; around 6:30 p.m California Time. Butte County Sheriff Kory Honea said they acted fast to rather be “safe than sorry.”

“DO NOT TRAVEL NORTH TOWARD OROVILLE,” the Yuba County Office of Emergency Services said on Facebook, urging evacuees to travel safely in all other directions and help the elderly.

Thousands of people from Yuba County and Sutter County have been filmed being evacuated from local towns and communities, with vehicles creating long traffic jams.

The emergency is the first time in the 48-year-old dam’s history that an uncontrolled spillway is being used, local NBC affiliate KCRA-TV reported.

Heavy rains and snow that struck California this winter have resulted in the dam’s reservoir being filled up to the point of overspill. On Thursday, the works to release water from the dam began after chunks of concrete from the spillway were discovered in the channel below.

On Friday, only 7 feet (2 meters) were left until the dam was to reach its full capacity.

The DWR has been using the emergency spillway instead of the damaged one to release the water.

The Sheriff said in a press conference:

“There are efforts being made to avert the crisis. I didn’t have the luxury seeing if everything was going to be OK — we needed to get people moving quickly in order to save lives in case the worst-case scenario came to fruition.”

He said they are looking into ways to shore up the spillway such as using helicopters to “drop rocks into the crevice.”

Honea said they’d drastically increased the amount of water allowed out of the main spillway, from 55,000 feet of water per second to 100,000. Earlier in the day, officials said the water was about 8 inches above the crest — by evening that was down to 2 inches, Honea said.

“It’s definitely one of those white-knuckle moments,” said Jay Lund, an engineering professor at UC Davis. “They’re evacuating downstream as well they should, but it hasn’t busted yet and the goal is to get the water level down below the lip.”

The erosion comes from the water running down the side of the hill that’s supposed to be dry. But it’s unreinforced and hence the water hauls dirt away as it goes over.

“The problem is that if it erodes too much it jeopardizes the integrity of the structure,” he said, meaning the spillway and not the dam itself.


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