http://www.sfgate.com/news/article/Oroville-Dam-spillway-hole-erosion-water-reservoir-10920358.php

Gaping hole in Oroville Dam spillway is growing, officials warn

Stormwater and snowmelt filled up the reservoir this week, necessitating releases on the spillway to the Feather River. The cement outlet was closed Tuesday after officials noticed water was flowing irregularly. After stopping the flow, engineers found a gaping hole in the concrete chute. By Thursday, the hole had grown to about 45-feet-deep and 300-feet-wide by 500-feet-long, according to a KCBS report.

On Friday the Butte Sheriff released a statement suggesting that an unpaved emergency spillway would likely be used for the first time ever. Crews were clearing trees and brush this week in the event that a release was needed. But during the noon hour Friday, the department posted an update on the flow suggesting that the emergency release is not imminent.

"Water flow over the Oroville Spillway is currently at 65,000 cfs (cubic feet per second). At the current rate of release, and with the current weather forecast, DWR officials do not believe use of the Emergency Spillway will take place," the department wrote on Facebook.

Situated in the western foothills of the Sierra, Lake Oroville is the second-largest man-made reservoir in California after Shasta. It's a key flood-control and water-storage facility within the California State Water Project, and its fresh water releases control salinity intrusion into the Sacramento-San Joaquin Delta and protect the health of fish and wildlife. As of Friday morning, the lake was at 98 percent capacity.

Earlier this week, photos of the damage and chunks of concrete yanked from the mile-long spillway went viral on social media. Engineers don't know what caused the cave-in that is expected to keep growing until it reaches bedrock.

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http://www.sfgate.com/news/article/Oroville-Dam-spillway-hole-erosion-water-reservoir-10920358.php

Gaping hole in Oroville Dam spillway is growing, officials warn

That's going to be one very expensive repair.

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Grant
Darwin NT

That's really worrying on so many fronts - how much damage has been done to the dam's structure, how long will it take to repair, how much of the reservoir capacity be reduced during the repairs, what would happen if the dam let's go, and so on.

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Bob Smith
Member of Seti PIPPS (Pluto is a Planet Protest Society)
Somewhere in the (un)known Universe?

From what I've read the dam is at 98% of capacity, and they tested the spillway up to 65,000cfs of DHMO, 65,000 is the output, the input is double that, and they have concrete trucks to make repairs with I think, which sounds like a lot grout. Oh and the emergency spillway has trees in it that are currently being cut down and removed, is unpaved, so far has no holes and is unused, unlike what is pictured which is the main spillway, and is very holey.

900' depth was reached in 2013, max depth is 901'. Oroville dam opened in 1968, so it's a 49 year old structure, testing of the spillway was done with chains, one sound says there are voids, another says no voids, voids caused this, seems they happen a lot from what I've read. And yes as the article at the link says, the bill has become due on Oroville dam.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

One looks at the picture of the hole and what do you see?

Joints.

What does water do? Find a way to seep through joints.

What does flowing water do? Erode or undermine.

My guess is the entire spillway will have to be rebuilt. Can't believe that any engineer ... well yes I can. Some engineer likely was told it was for emergency use and not expected to be used at all. But then why the extra unpaved one? Or did they figure out after it was built they were going to have a failure?!

Going to cost money. Water rates in California are going up! Well, if you get water from the state water projects anyway.

Going to have to tear it all out, regrade the earth, and then build a continuous surface spillway so there is no route for water to undermine it. That likely means the lake will have to be drawn way down and kept that way until the repairs are complete so they don't lose the flood control capacity of the lake. And we are going to have record snow melt in a couple months running into that nearly full lake. What a mess.

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One looks at the picture of the hole and what do you see?

Joints.

What does water do? Find a way to seep through joints.

What does flowing water do? Erode or undermine.

My guess is the entire spillway will have to be rebuilt. Can't believe that any engineer ... well yes I can. Some engineer likely was told it was for emergency use and not expected to be used at all. But then why the extra unpaved one? Or did they figure out after it was built they were going to have a failure?!

Going to cost money. Water rates in California are going up! Well, if you get water from the state water projects anyway.

Going to have to tear it all out, regrade the earth, and then build a continuous surface spillway so there is no route for water to undermine it. That likely means the lake will have to be drawn way down and kept that way until the repairs are complete so they don't lose the flood control capacity of the lake. And we are going to have record snow melt in a couple months running into that nearly full lake. What a mess.

Nope.

Only the parts of the spillway not on Bedrock would need repairs...

Gov Brown has declared a state of Emergency in 49 out of 58 counties statewide, and has asked the tRump administration for a Federal disaster declaration too. Which will free up Federal money for CA.

Without this spillway, drawing down the lake is not possible, as this damaged spillway, is the main spillway, the emergency spillway is unpaved and being cleared of trees and is only for amounts above 90% of capacity.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

One looks at the picture of the hole and what do you see?

Joints.

What does water do? Find a way to seep through joints.

What does flowing water do? Erode or undermine.

My guess is the entire spillway will have to be rebuilt. Can't believe that any engineer ... well yes I can. Some engineer likely was told it was for emergency use and not expected to be used at all. But then why the extra unpaved one? Or did they figure out after it was built they were going to have a failure?!

Going to cost money. Water rates in California are going up! Well, if you get water from the state water projects anyway.

Going to have to tear it all out, regrade the earth, and then build a continuous surface spillway so there is no route for water to undermine it. That likely means the lake will have to be drawn way down and kept that way until the repairs are complete so they don't lose the flood control capacity of the lake. And we are going to have record snow melt in a couple months running into that nearly full lake. What a mess.

Nope.

Only the parts of the spillway not on Bedrock would need repairs...

That would be all of it. Spillways are designed with very specific slopes to control the speed of the water flow and that would have required essentially the entire length to have fill dirt under it so the slope could be adjusted.

Gov Brown has declared a state of Emergency in 49 out of 58 counties statewide, and has asked the tRump administration for a Federal disaster declaration too. Which will free up Federal money for CA.

Without this spillway, drawing down the lake is not possible, as this damaged spillway, is the main spillway, the emergency spillway is unpaved and being cleared of trees and is only for amounts above 90% of capacity.

Lake is at 100%+ Water is now over the emergency spillway height, and downstream flood control has been lost. This is the real emergency.

As to draw down, there is a hydroelectric power plant, which can draw down the lake. Not as fast at the river is presently filling the lake however. When the spring snow melt hits there may be some very serious flooding in the Sacramento delta.

Oh, as a bonus, now they can only get cement trucks in from the wrong side of the spillway as the correct side has an uncontrolled river flowing down it! This job just got very hard and extra expensive.

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One looks at the picture of the hole and what do you see?

Joints.

What does water do? Find a way to seep through joints.

What does flowing water do? Erode or undermine.

My guess is the entire spillway will have to be rebuilt. Can't believe that any engineer ... well yes I can. Some engineer likely was told it was for emergency use and not expected to be used at all. But then why the extra unpaved one? Or did they figure out after it was built they were going to have a failure?!

Going to cost money. Water rates in California are going up! Well, if you get water from the state water projects anyway.

Going to have to tear it all out, regrade the earth, and then build a continuous surface spillway so there is no route for water to undermine it. That likely means the lake will have to be drawn way down and kept that way until the repairs are complete so they don't lose the flood control capacity of the lake. And we are going to have record snow melt in a couple months running into that nearly full lake. What a mess.

Nope.

Only the parts of the spillway not on Bedrock would need repairs...

That would be all of it. Spillways are designed with very specific slopes to control the speed of the water flow and that would have required essentially the entire length to have fill dirt under it so the slope could be adjusted.

Gov Brown has declared a state of Emergency in 49 out of 58 counties statewide, and has asked the tRump administration for a Federal disaster declaration too. Which will free up Federal money for CA.

Without this spillway, drawing down the lake is not possible, as this damaged spillway, is the main spillway, the emergency spillway is unpaved and being cleared of trees and is only for amounts above 90% of capacity.

Lake is at 100%+ Water is now over the emergency spillway height, and downstream flood control has been lost. This is the real emergency.

As to draw down, there is a hydroelectric power plant, which can draw down the lake. Not as fast at the river is presently filling the lake however. When the spring snow melt hits there may be some very serious flooding in the Sacramento delta.

Oh, as a bonus, now they can only get cement trucks in from the wrong side of the spillway as the correct side has an uncontrolled river flowing down it! This job just got very hard and extra expensive.

The articles online said parts of the main spillway are on bedrock, and the emergency spillway is unpaved and full of trees. And that it is the main spillway that is damaged.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

This is from KRCA:

OROVILLE, Calif. (KCRA) —

Water has begun to slowly flow over the Oroville Dam emergency spillway Saturday morning as Lake Oroville has reached full capacity and water outflows by way of the damaged spillway have decreased.

As of 12 p.m. Saturday, the California Department of Water Resources believes water will continue to spill over the emergency spillway for the next 38 to 56 hours.

This is the first time the uncontrolled emergency spillway has been used in the dam's 48-year history and could only happen one the lake reached full capacity at 901 feet elevation. Flows over this secondary chute will likely range between 6,000 and 12,000 cfs, the California Department of Water Resources said.

DWR is continuously monitoring the damaged spillway to ensure no more erosion occurs. They are letting out 55,000 cfs on the spillway to prevent further erosion to it.

The DWR acting director's objective is to have a new or repaired spillway in place before the next wet season, hopefully by October.

He added that crews will have to turn off the spillway during the next dry period to fix the eroded spillway. During this process, water may flow over the emergency spillway again, DWR's acting director said. He continued saying this has to be done to ensure more water could be released from the damaged spillway in the future.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

Have to admit I can't fathom why they would bother clearing trees & shrubs from the auxiliary spillway. They would stop any significant erosion in the area and their impact on the flow of water would be minimal- it's a relatively steep slope & broad area.

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Grant
Darwin NT

Have to admit I can't fathom why they would bother clearing trees & shrubs from the auxiliary spillway. They would stop any significant erosion in the area and their impact on the flow of water would be minimal- it's a relatively steep slope & broad area.

My guess is that they think once the trees are pulled loose by the rushing water, they will be able to cause damage to things they hit, more than the water by itself would. Or, they may think the trees will run into other obstacles that can't/won't be pulled loose and cause impromptu dams of their own, leading to uncontrolled flooding away from the spillway area.

http://www.supercartoons.net/cartoon/1040/bugs-bunny-wet-hare.html

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David
Sitting on my butt while others boldly go,
Waiting for a message from a small furry creature from Alpha Centauri.

Have to admit I can't fathom why they would bother clearing trees & shrubs from the auxiliary spillway. They would stop any significant erosion in the area and their impact on the flow of water would be minimal- it's a relatively steep slope & broad area.

My guess is that they think once the trees are pulled loose by the rushing water, they will be able to cause damage to things they hit, more than the water by itself would. Or, they may think the trees will run into other obstacles that can't/won't be pulled loose and cause impromptu dams of their own, leading to uncontrolled flooding away from the spillway area.

I also beginning to think the DWR after promising the auxiliary spillway would stay dry that someone reran the number about how much water is coming in to the dam and went oops. IIRC they said they took out the trees so they don't destroy some downstream things, like the fish hatchery, which is needed for salmon spawning because the dam is there and they didn't build a fish ladder. I'm also beginning to get a feel that someone in the DWR simply refuses to tell the public the true picture, or they can't forecast the snow melt rate or the amount of rain. This how many years after the dam opened and they don't have good data?!

At least I hope Oroville dam doesn't get remembered like the St. Francis dam.

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Have to admit I can't fathom why they would bother clearing trees & shrubs from the auxiliary spillway. They would stop any significant erosion in the area and their impact on the flow of water would be minimal- it's a relatively steep slope & broad area.

My guess is that they think once the trees are pulled loose by the rushing water, they will be able to cause damage to things they hit, more than the water by itself would. Or, they may think the trees will run into other obstacles that can't/won't be pulled loose and cause impromptu dams of their own, leading to uncontrolled flooding away from the spillway area.

I also beginning to think the DWR after promising the auxiliary spillway would stay dry that someone reran the number about how much water is coming in to the dam and went oops. IIRC they said they took out the trees so they don't destroy some downstream things, like the fish hatchery, which is needed for salmon spawning because the dam is there and they didn't build a fish ladder. I'm also beginning to get a feel that someone in the DWR simply refuses to tell the public the true picture, or they can't forecast the snow melt rate or the amount of rain. This how many years after the dam opened and they don't have good data?!

At least I hope Oroville dam doesn't get remembered like the St. Francis dam.

Oroville dam opened in 1968, that's 49 years ago.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

At least I hope Oroville dam doesn't get remembered like the St. Francis dam.

Unlikely.
The spillway erosion is a good distance away from the dam wall. It would take a lot more erosion a lot closer to the wall to undermine it.

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Grant
Darwin NT

At least I hope Oroville dam doesn't get remembered like the St. Francis dam.

Unlikely.
The spillway erosion is a good distance away from the dam wall. It would take a lot more erosion a lot closer to the wall to undermine it.

You are right. The built the spill way over some good bedrock.
But estimated $200 million to repair. I expect that 45 is going to put some strings on any emergency funding.

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If you live down stream from the Dam, EVACUATE!

Emergency spill way expected to fail within the hour.

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Weather Channel Oroville dam

Mandatory Evacuation Ordered, could affect the Feather and Sacramento Rivers, and areas downstream of the Oroville dam.
http://www.latimes.com/local/lanow/la-me-ln-oroville-update-20170212-story.htmlhttp://www.latimes.com/local/lanow/la-me-ln-oroville-update-20170212-story.html
http://www.sfgate.com/news/article/Lake-Oroville-discharging-water-over-dam-s-10926950.php
Live video at Breitbart:
http://www.breitbart.com/california/2017/02/12/emergency-evacuations-ordered-oroville-dam-spillway-fails/

LA Times wrote:

Residents of Oroville and nearby towns were ordered to immediately evacuate on Sunday afternoon after a “hazardous situation” developed involving an emergency spillway at the Oroville Dam.

The National Weather Service said the auxiliary spillway at the Oroville Dam was expected to fail by 5:45 p.m., which could send an “uncontrolled release of flood waters from Lake Oroville.”

Those in Oroville were asked to flee northward toward Chico. In Yuba County, those in the valley areas were urged to take routes to the east, south, or west.

“This is not a Drill. This is not a Drill. Repeat this is not a drill,” the National Weather Service said. Authorities urged residents to contact neighbors and family members and reach out to the elderly and assist them in evacuating.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's

At least I hope Oroville dam doesn't get remembered like the St. Francis dam.

Unlikely.
The spillway erosion is a good distance away from the dam wall. It would take a lot more erosion a lot closer to the wall to undermine it.

Seems too possible now.

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At least I hope Oroville dam doesn't get remembered like the St. Francis dam.

Unlikely.
The spillway erosion is a good distance away from the dam wall. It would take a lot more erosion a lot closer to the wall to undermine it.

Seems too possible now.

News conference right now. The Dam is not at risk. The spillway is.

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I sent a PM to TL, I'm not sure where He lives in N. CA.

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The T1 Trust, PRR T1 Class 4-4-4-4 #5550, 1 of America's First HST's