More than 180,000 people in northern California have been told to evacuate their homes after an overflow channel at the tallest dam in the US was weakened by heavy rainfall.
The emergency spillway of the 770 ft (230m) tall Oroville Dam was close to collapse, officials said.
The excess water has now stopped flowing.
However, late on Sunday Butte County Sheriff Kory Honea said the evacuation orders remained in place.
Water levels in the reservoir have risen following heavy rain and snow after years of severe drought.
It is the first time that Lake Oroville has experienced such an emergency in the dam's near 50-year history.
The California Department of Water Resources said earlier on Sunday afternoon that it was releasing as much as 100,000 cubic feet (2,830 cubic metres) of water per second from the main spillway to try to drain the lake.
In a statement posted on social media on Sunday afternoon, the sheriff for the area around the Lake Oroville dam ordered residents to evacuate, repeating three times that it was "NOT a drill".

Residents of Oroville, a town of 16,000 people 65 miles (105km) north of Sacramento, were told to head north.
There was gridlock on roads heading out of the town, with some evacuees complaining that they should have been given more warning.
Butte County's official Twitter feed shared news of emergency shelters, and reported that many hotels were fully booked in the wider area.
Other cities affected should follow orders from their local law enforcement agencies, officials said.

Earlier in the week engineers began releasing water from the dam after noticing large chunks of concrete were missing from a spillway.
On Friday, California Governor Jerry Brown asked the Federal Emergency Management Agency to declare a major disaster due to flooding and mudslides brought on by storms.

 CptJake wrote:
As someone who dealt Hurricane Matty exacerbated by dams upstream failing, I genuinely hope they get that spillway stabilized quickly.

Three environmental groups — the Friends of the River, the Sierra Club and the South Yuba Citizens League — filed a motion with the federal government on Oct. 17, 2005, as part of Oroville Dam’s relicensing process, urging federal officials to require that the dam’s emergency spillway be armored with concrete, rather than remain as an earthen hillside.

The groups filed the motion with FERC, the Federal Energy Regulatory Commission. They said that the dam, built and owned by the state of California, and finished in 1968, did not meet modern safety standards because in the event of extreme rain and flooding, fast-rising water would overwhelm the main concrete spillway, then flow down the emergency spillway, and that could cause heavy erosion that would create flooding for communities downstream, but also could cause a failure, known as “loss of crest control.”

FERC rejected that request, however, after the state Department of Water Resources, and the water agencies that would likely have had to pay the bill for the upgrades, said they were unnecessary. Those agencies included the Metropolitan Water District of Southern California, which provides water to 19 million people in Los Angeles, San Diego and other areas, along with the State Water Contractors, an association of 27 agencies that buy water from the state of California through the State Water Project. The association includes the Metropolitan Water District, Kern County Water Agency, the Santa Clara Valley Water District and the Alameda County Water District.

Federal officials at the time said that the emergency spillway was designed to handle 350,000 cubic feet per second and the concerns were overblown.

“It is important to recognize that during a rare event with the emergency spillway flowing at its design capacity, spillway operations would not affect reservoir control or endanger the dam,” wrote John Onderdonk, a senior civil engineer with FERC, in the Federal Energy Regulatory Commission’s San Francisco Office, in a July 27, 2006, memo to his managers.

“The emergency spillway meets FERC’s engineering guidelines for an emergency spillway,” he added. “The guidelines specify that during a rare flood event, it is acceptable for the emergency spillway to sustain significant damage.”

 Necros wrote:
Not too long ago I watched something on the history channel, or maybe nat geo, about how the majority of our dams and bridges are so old many are very close to failing. Pretty scarey. Glad I don't live down river of anything.

Here in philly, they just had to shut down the PA Turnpike bridge that connects you to the NJ turnpike (2 pretty major roads 'round here) cuz they found a small fracture near some random rivet.. Last I heard it's shut down indefinitely for repairs and no date et for reopening at all.

 TheCustomLime wrote:
First we have years of unrelenting drought. Now we have too much water.

Nature! Make up your mind, damn it!

SemperMortis wrote:
Be nice if CA had listened to those studies and provided enough money to armor the emergency spillway so this wouldn't have been a problem. Ohh well, I guess it was more important to spend that money elsewhere.

 jhe90 wrote:

SemperMortis wrote:
Be nice if CA had listened to those studies and provided enough money to armor the emergency spillway so this wouldn't have been a problem. Ohh well, I guess it was more important to spend that money elsewhere.

Aye that would of been a good idea during the dry times to work on the dam when your water levels low.
The emergancy spill way never gonna be needed when your half dry and percentages low. Ideal timing.

SemperMortis wrote:

 jhe90 wrote:

SemperMortis wrote:
Be nice if CA had listened to those studies and provided enough money to armor the emergency spillway so this wouldn't have been a problem. Ohh well, I guess it was more important to spend that money elsewhere.

Aye that would of been a good idea during the dry times to work on the dam when your water levels low.
The emergancy spill way never gonna be needed when your half dry and percentages low. Ideal timing.

yup, and apparently they were warned that the actual spillway was damaged so they needed to repair that. But F it, we don't need it right?

 jhe90 wrote:

SemperMortis wrote:

 jhe90 wrote:

SemperMortis wrote:
Be nice if CA had listened to those studies and provided enough money to armor the emergency spillway so this wouldn't have been a problem. Ohh well, I guess it was more important to spend that money elsewhere.

Aye that would of been a good idea during the dry times to work on the dam when your water levels low.
The emergancy spill way never gonna be needed when your half dry and percentages low. Ideal timing.

yup, and apparently they were warned that the actual spillway was damaged so they needed to repair that. But F it, we don't need it right?

Aye... I'm guessing they don,t live under the dam....

SemperMortis wrote:

 jhe90 wrote:

SemperMortis wrote:

 jhe90 wrote:

SemperMortis wrote:
Be nice if CA had listened to those studies and provided enough money to armor the emergency spillway so this wouldn't have been a problem. Ohh well, I guess it was more important to spend that money elsewhere.

Aye that would of been a good idea during the dry times to work on the dam when your water levels low.
The emergancy spill way never gonna be needed when your half dry and percentages low. Ideal timing.

yup, and apparently they were warned that the actual spillway was damaged so they needed to repair that. But F it, we don't need it right?

Aye... I'm guessing they don,t live under the dam....

Yeah, California is kind of full of double standards. My favorite is California's legislation voting to strip gun rights from the citizens but give themselves an exemption
[url]
http://www.washingtontimes.com/news/2011/jun/6/one-law-for-us-another-for-you/[/url]

 Frazzled wrote:
Is there an update? I cannot find one.

Yes, as someone noted, a major works program is needed for our infrastructure. It would probably be an excellent program if done right. if only we had a President who liked construction projects...

 hotsauceman1 wrote:

 Frazzled wrote:
Is there an update? I cannot find one.

Yes, as someone noted, a major works program is needed for our infrastructure. It would probably be an excellent program if done right. if only we had a President who liked construction projects...

we can go to space and plant a flag, but we can fix a bridge.

SemperMortis wrote:
Be nice if CA had listened to those studies and provided enough money to armor the emergency spillway so this wouldn't have been a problem. Ohh well, I guess it was more important to spend that money elsewhere.

 AegisGrimm wrote:

SemperMortis wrote:
Be nice if CA had listened to those studies and provided enough money to armor the emergency spillway so this wouldn't have been a problem. Ohh well, I guess it was more important to spend that money elsewhere.

Welcome to every bridge and dam in this country.

 AegisGrimm wrote:

SemperMortis wrote:
Be nice if CA had listened to those studies and provided enough money to armor the emergency spillway so this wouldn't have been a problem. Ohh well, I guess it was more important to spend that money elsewhere.

Welcome to every bridge and dam in this country.