NFT: Oroville Dam

on the edge of a major catastrophe there - hopefully it doesn't happen. That dam is huge.

and I started following the live updates and I think I missed some sleep. Can't believe how little coverage it was getting up until that point.

Back in 2005, they knew they had problem.

Dam was not built on bedrock.....
Which they now acknowledge was a mistake.

But instead of fixing it.... California decided to build a high speed rail system.

This feels like a real life disaster movie.....They are fighting to lower it by 50 feet by Wednesday.....When a storm is expected.

Scary stuff.

EPA requirements are so strict and the ecological consequences so negative that I wonder if it will ever be rebuilt.
And how , in god's name, do you build on less than bedrock.
Irrelevant perhaps, but the Manhattan side of the Brooklyn Bridge is Not sitting on Bedrock. As the first really large suspension bridge they over turned a huge caiisson or wooden type barge and sank it by piling rocks on the underside (now the top side). Then sand hogs - who suffered from the undiagnosed and unknown Bends - literally dug the sand out from under it. They found their bedrock on the Brooklyn side, but had to quit on the Manhattan side.

that said the dam itself was in no danger of collapsing but that the spillways, which are separate structures from the dam, are the danger. The threat was that the dam was at 100% capacity and there is a storm due Wednesday or Thursday, which is why they are lowering it as fast as practicable.

thought the threat was the crumbling spillways, not the dam itself. In any event, it has the makings of a real catastrophe. As someone said, they knew many years ago the spillways were decaying, but did nothing. This is apparently the largest dam in the U.S., even bigger than the Hoover dam.

In comment 13360315 George from PA said:

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But instead of fixing it.... California decided to build a high speed rail system.

This has nothing to do with High Speed Rail

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The Bush administration 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, and the State Water Contractors, an association of 27 agencies that buy water from the state of California through the State Water Project. 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.

The contractors who run the water systems that get water from the Oroville dam would have been on the hook for the costs and they didn't want to pay for it. Ultimately FERC, The Federal Energy Regulatory Commission, decided that they didn't have to.

And it's not the dam that may fail, it's the spillways.


State was warned about inadequacy of emergency spillway - ( New Window )

and also the fact that the lake is brimming due to all the rain. The busted spillway could eventually (eventually) create enough erosion that it starts to undermine the main dam. Also, when the lake brims, the water automatically spills over the emergency spillway (different from the main spillway). The emergency spillway was never needed in the history of the dam, but earlier this week due heavy lake infows it was used for the first time. The problem with the emergency spillway is that it is just that, for emergency only. It is simply the lowest "edge of the bathtub". Water flowing over the emergency spillway, as they have now found out the hardway, erodes the crap out of the hillside and could also eventually (eventually) undermine the main part of the dam. It all boils down to too much rain and with the reservoir being full (very rare for this time of year) they have no choice but to release shitloads of water in order to get ahead of the coming rains and spring thaw (and hope that releasing the water doesnt erode the main dam). And so the towns below the dam dont have the flood control protection they have previously enjoyed.

Thats my understanding. Happy to be corrected if im wrong on anything. Its simply an incredible situation considering the recent drought and the fact that nearly all of the CA reservoirs were pretty much empty a year ago. The sierras have gotten a shit ton of snow this year, so the spring thaw will be epic. And yet all of the reservoirs are full. There is nowhere for the spring thaw to go as of right now. Crazy. This situation has a long way to play out.

The dam is not in danger of failing. A failure of the emergency spillway would in of itself be a major disaster.

Unfortunately, this crisis is far from over. The immediate forecast for heavy rain and the incredible amount of snow that has fallen in the Sierra's will likely strain the spillways further.

The dam itself is 770 feet high making it the tallest dam in the US.




Oroville dam - ( New Window )

Earlier this week the water brimmed and started spilling over the emergency spillway. That water overflow has now stopped because the lake level was lowered enough. But a lot of that yellow shaded area was eroded after just a day or two of over flow. The yellow shaded area was supposed to be able to handle a couple hundred thousand cubic feet per second (cfs) but it had never been used. They found out the hard way that 12,000 cfs (the amt going over the emergency spillway earlier this week) was enough to heavily erode that yellow shaded hillside.

Meanwhile, they are blasting 100,000cfs down the main spillway (the white line) in order to lower the lake level. But right about where the label line intersects with the spillway line in that pic there is a huge hole. The main spillway is simply a concrete trough whose purpose is to discharge water far down the jill and away from the base of the main damn. With the erosion now happening roughly halfway down the main spillway, that is also a huge concern because it can lead to undermining the main dam. The actually main spillway gates at the edge of the lake are working fine.

back in 05? All I saw was an article that said that environmental groups predicted it would fail, but my guess is a lot of people would dismiss anything those environment groups suggested out of hand.

Did authorities believe the spillway was in danger prior to this year's abnormal rainfalls?

So are we blaming high speed rail or water?

and raise you solar projects... Everyone has a narrative.

In comment 13360446 Dunedin81 said:

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and raise you solar projects... Everyone has a narrative.

Well played sir. I fold. Solar takes the narrative.

Can you imagine if you proposed spending money on "fixing" a Dam? You would be kicked out of the budget meeting.

Water has already been pouring over it and if the erosion would cause the concrete lip to fail the emergency spillway essentially becomes a pathway for the water. The problem is compounded by the main spillway breaking apart in a large section.

Starting Wednesday. Scary.

With the long term weather forecasts they have and the dam rapidly filling, why did they wait until late last week to begin controlled releases?

dramatically limited the amount of water they felt they could safely release and what began the crisis. If the spillway didn't ever fail they probably would have been able to better stay ahead of it to this point.

In comment 13360685 steve in ky said:

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dramatically limited the amount of water they felt they could safely release and what began the crisis. If the spillway didn't ever fail they probably would have been able to better stay ahead of it to this point.

But if they started 2-3 weeks earlier they would have had more time to respond to the problem.

In comment 13360689 njm said:

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In comment 13360685 steve in ky said: Quote: dramatically limited the amount of water they felt they could safely release and what began the crisis. If the spillway didn't ever fail they probably would have been able to better stay ahead of it to this point. But if they started 2-3 weeks earlier they would have had more time to respond to the problem.

True but they would have never expected the main spillway to break apart and the way I understand it if it hadn't they would have simply released more through it and there likley wouldn't be any issue.

But who knows maybe with this much rain it would have occurred regardless but in fairness to them the emergency spillway has never been breached in the dams entire history (50+ years). This is unprecedented.

The silt that has gathered at the base of the dam might prevent it from freeing that water used to feed California for the next year.

The dam itself is fine and is in no danger. The main spillway is damaged which is restricting the amount of water they can release out of it.

Due to all of the recent rains, the lake is filling faster than the damaged main spillway can release water.

The emergency spillway is an earthen dyke that basically acts similarly to an overflowing sink. Once the water level reaches a certain height, water starts to flow over the emergency spillway. There is no control of the flow over this emergency spillway. The emergency spillway has never been used before.

In 2006, a couple of environmental groups were concerned that if the emergency spillway needed to be used, it was prone to erosion since it was 50 years old and had never been used. They proposed to line the earthen spillway with concrete to mitigate. Due to cost concerns, the state declined.

As the emergency spillway was being used on Sunday, the erosion rate was high enough that it was likely the emergency spillway was going to lose the top couple of feet of the spillway in some places which would have led to uncontrolled flows down.

The Lake is 25 square miles. A 1 foot breach of the top of the emergency spillway has the potential to unleash up to 5.2 billion gallons of water uncontrolled to some degree.

not reading articles about this on Breitbart -- especially the comments section.

In comment 13360712 steve in ky said:

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In comment 13360689 njm said: Quote: In comment 13360685 steve in ky said: Quote: dramatically limited the amount of water they felt they could safely release and what began the crisis. If the spillway didn't ever fail they probably would have been able to better stay ahead of it to this point. But if they started 2-3 weeks earlier they would have had more time to respond to the problem. True but they would have never expected the main spillway to break apart and the way I understand it if it hadn't they would have simply released more through it and there likley wouldn't be any issue. But who knows maybe with this much rain it would have occurred regardless but in fairness to them the emergency spillway has never been breached in the dams entire history (50+ years). This is unprecedented.

This is not entirely correct. The main spillway can only release at a certain flowrate. The recent rains exceeded that flowrate, so even if the spillway was working properly, the lake would still be filling.

The area of catchment for this lake is huge. It captures all sorts of mountain runoff, so even a storm that brings an inch of rain has the potential to add, for lack of better term, a shit ton of water at a rate higher than they can release it.

Why did they feel the need to point out the parking lot in that picture?

I thought that is what we have been saying but you did a better job of detailing it, thanks.

In comment 13360743 steve in ky said:

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I thought that is what we have been saying but you did a better job of detailing it, thanks.

Steve wasn't directed at you, there were other comments talking about the dam itself, so i wanted to clarify everything in one post, haha.

In comment 13360741 BH28 said:

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In comment 13360712 steve in ky said: Quote: In comment 13360689 njm said: Quote: In comment 13360685 steve in ky said: Quote: dramatically limited the amount of water they felt they could safely release and what began the crisis. If the spillway didn't ever fail they probably would have been able to better stay ahead of it to this point. But if they started 2-3 weeks earlier they would have had more time to respond to the problem. True but they would have never expected the main spillway to break apart and the way I understand it if it hadn't they would have simply released more through it and there likley wouldn't be any issue. But who knows maybe with this much rain it would have occurred regardless but in fairness to them the emergency spillway has never been breached in the dams entire history (50+ years). This is unprecedented. This is not entirely correct. The main spillway can only release at a certain flowrate. The recent rains exceeded that flowrate, so even if the spillway was working properly, the lake would still be filling. The area of catchment for this lake is huge. It captures all sorts of mountain runoff, so even a storm that brings an inch of rain has the potential to add, for lack of better term, a shit ton of water at a rate higher than they can release it.

Of course there is a limit and I did say that with this much rain maybe would have occurred anyway but that is only speculation. The fact is the crisis began with the structural failure of the main spillway.

main spillway that has now led to the huge hole. Best I can find is a week or so ago. But that seems odd to me. In my completely non-expert opinion, if a crack only just formed it probably would have been caused by erosion under the concrete spillway from recent rainfall. But they should have seen that happening well before it eroded the underside of the spillway enough to crack it. Or was the crack known about for a long time and perhaps they simply didnt think it would lead to a hole in the spillway?

As for the comments about the dam not being anchored to bedrock.. This is an earthen dam.

In comment 13360742 Pete in MD said:

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Why did they feel the need to point out the parking lot in that picture?

I'm speculating for a frame of reference for the locals. There is a road, a parking lot and boat ramp there so local people would likley know where the breach is in relation to those.

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In comment 13360742 Pete in MD said:

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Why did they feel the need to point out the parking lot in that picture?

For tourists who might want to come watch the disaster.

Basically the reservoir was about 1/2 full at the start of December. The amount of rain they have had filled the reservoir in that short time.

You were correct on the emergency spillway. The emergency spillway is a concrete wall. There is no concern with losing "the top couple feet" of this wall. The concern is that after the water spills over the wall, it simply runs down the hillside. That has the potential Erode the underside of the entire concrete wall (not just the top couple feet). If the concrete wall of the emergency spillway were to be compromised, that would lead to the breach of more than a couple feet of lake water (if it were near full pool).

Link - ( New Window )

Main Spillway is concrete and has issues of its own (sinkhole takes out part of concrete flow containment and may indicate erosion issues for the actual dam). The emergency spillway is as RH and others have stated: earthen. The more water that rushes over, the more erosion which means even more water rushing over and more erosion. That erosion impacts the Main Spillway and the Dam eventually. Please review the pictures provided above.

Im out.

In comment 13360779 Taggart said:

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You were correct on the emergency spillway. The emergency spillway is a concrete wall. There is no concern with losing "the top couple feet" of this wall. The concern is that after the water spills over the wall, it simply runs down the hillside. That has the potential Erode the underside of the entire concrete wall (not just the top couple feet). If the concrete wall of the emergency spillway were to be compromised, that would lead to the breach of more than a couple feet of lake water (if it were near full pool).

Its the same concept, you have water eroding the earthen part of the emergency spillway leading to uncontrolled release of water. The 1 foot thing was just an example of how much water could be released with a 1 foot breach.

Thank God we don't use the metric system, if it were a metric shit ton we'd be fucked.

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In comment 13360734 BH28 said:

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The emergency spillway is an earthen dyke that basically acts similarly to an overflowing sink.

Sounds like someone I went to college with.

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The emergency spillway has never been used before.

Oh. Never mind.

In comment 13361155 njm said:

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That's good news, it has to be a relief for those whose lives were interrupted. Hopefully they have gotten a handle on it and the weather cooperates going forward.


Thanks for posting the update

In comment 13360737 santacruzom said:

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not reading Breitbart

I fixed that for you.

In comment 13360330 grizz299 said:

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EPA requirements are so strict and the ecological consequences so negative that I wonder if it will ever be rebuilt. And how , in god's name, do you build on less than bedrock. Irrelevant perhaps, but the Manhattan side of the Brooklyn Bridge is Not sitting on Bedrock. As the first really large suspension bridge they over turned a huge caiisson or wooden type barge and sank it by piling rocks on the underside (now the top side). Then sand hogs - who suffered from the undiagnosed and unknown Bends - literally dug the sand out from under it. They found their bedrock on the Brooklyn side, but had to quit on the Manhattan side.