Heavy traffic amid evacuation

5:59 p.m.

Aerial photos show traffic backed up along Highway 70 as people from Oroville try to escape to the north.

Flows boosted to try to avoid collapse

5:52 p.m.

Releases through the main spillway at Oroville Dam have been boosted to 100,000 cubic feet per second from 55,000 cfs in hopes of easing pressure on the emergency spillway before a failure occurs, officials said Sunday night.

Kevin Dossey, a Department of Water Resources engineer and spokesman said “it might help” to alleviate the pressure.

So far, Dossey said, the emergency spillway’s concrete lip at the top has not crumbled, although the hillside had “eroded to within several feet” of the big concrete structure.

Marysville and Yuba County ordered evacuated; officials unsure how Sacramento could be hit

Marysville, Yuba County ordered to evacuate

5:42 p.m.

Marysville police say the city and Yuba County are under mandatory evacuation orders because of the feared collapse of the emergency spillway at Lake Oroville Dam. Yolo County officials said in a tweet that they do not expect any impact.

Witnesses reported a heavy police presence in the city.

“The hazardous situation concerning the Oroville Dam auxiliary spillway is NOT expected to impact Yolo County,” the county said.

Cal OES spokesman Brad Alexander said officials were activating the state emergency operations center and could not immediately address how waterlogged Sacramento County might be affected.

“I can’t answer that right now,” Alexander said.

“It’s uncontrolled. It’s uncontrolled

‘It’s uncontrolled’

5:30 p.m.

Fearing a gush from Lake Oroville if the emergency spillway collapses, officials are releasing as much as 100,000 cubic feet per second from the main, heavily damaged spillway in a frantic effort to drain the lake below where it spills out the emergency structure when the lake reaches maximum capacity, said Kevin Dossey, an engineer and Department of Water Resources spokesman.

The levee-line downstream channels in the Feather River could hold more than 150,000 cubic feet per second, said Maury Roos, a DWR hydrologist, but he said there’s a possibility that a levee could breach from the pressure.

Roos said that below where the Feather River merges with the Yuba River, levees are rated for a capacity of around 300,000 cfs.

When asked how much water could be released should the spillway collapse, DWR spokesman Chris Orrock said, “It’s uncontrolled. It’s uncontrolled.”

Dossey said the emergency spillway was rated to handle 250,000 cubic feet per second, but it began to show weakness Sunday at a small fraction of that. Flows through the spillway peaked at 12,600 cfs at 1 a.m. Sunday and were down to 8,000 cfs by midday.

Evacuation center at Silver Dollar Fairgrounds

5:15 p.m.

An evacuation center has been established for Oroville residents at the Silver Dollar Fairgrounds in Chico, according to the National Weather Service. The address is 2357 Fair St.

Butte County sheriff: “This is NOT A Drill.”

5 p.m.

The Butte County Sheriff’ Office released the following statement on Facebook:

This is an evacuation order.

Immediate evacuation from the low levels of Oroville and areas downstream is ordered.

A hazardous situation is developing with the Oroville Dam auxiliary spillway. Operation of the auxiliary spillway has lead to severe erosion that could lead to a failure of the structure. Failure of the auxiliary spillway structure will result in an uncontrolled release of flood waters from Lake Oroville. In response to this developing situation, DWR is increasing water releases to 100,000 cubic feet per second.

Immediate evacuation from the low levels of Oroville and areas downstream is ordered.

This in NOT A Drill. This in NOT A Drill. This in NOT A Drill.

Chris Orrock, a spokesman for the Department of Water Resources, told The Bee the failure happened as the bottom of the emergency spillway began to erode.

“It happened quickly,” he said.

Sutter County also put out an alert on Facebook:

We have received information about the potential for increased flows in the Feather River of as much as 100,000 cubic feet per second. We are gathering as much information as possible and will be providing additional information as soon as it is verified.

Officials warn of “imminent failure” at Oroville Dam’s emergency spillway

4:45 p.m.

Officials are warning those living downstream of Lake Oroville’s dam to evacuate because of a risk that the dam’s emergency spillway could collapse.

“They have what they expect to be an imminent failure of the axillary spillway,” said Mike Smith, a spokesman for the California Department of Forestry and Fire Protection. “What they’re expecting is as much as 30 vertical feet of the top of the spillway could fail and could fail within one to two hours. We don’t know how much water that means, but we do know that’s potentially 30 feet of depth of Lake Oroville.”

The Department of Water Resources, which operates the dam, said in a 4:42 p.m. Twitter post that the emergency spillway could fail within the next hour.

“Oroville residents evacuate northward,” the Tweet said.