Damaged Lake #OrovilleDam spillway being sacrificed with high releases – now about 4 feet to top

The Lake Oroville saga continues, yesterday we wondered if the collapse of the spillway might have been due to missing or substandard REBAR, and many experts weighed it on that topic. It now appears that there was REBAR there, and the failure was likely of a nature of lack of maintenance and age combined. It appears the earth underneath the spillway was compromised, and that led to the collapse of the structure without anything to support it.

orovillespillway

Click for video

Today, it is a race against time and water, as DWR has ramped up outflow to 65,000 cubic feet per second, and in doing so, is sacrificing the damaged spillway in hopes that there will not be an uncontrolled release from the emergency spillway, something that has never happened in the history of the dam. During the super El Niño of 1997-1998, it came within 1 foot of the emergence spillway. Now, given the fact that inflow is still exceeding outflow, and emergency release looks very likely.

Here’s video from yesterday showing the damage and concrete blowing out:

Unfortunately, the last update of data at 11:00AM PST today shows a water surface elevation value of 895.84 feet, or 4.16 feet to the top at the 900 foot mark where the emergency spillway starts to kick in.

The rate of rise has slowed from yesterday, and no new additional rain is expected today, but with afternoon temperatures expected to be above freezing well above 4000 feet, we are going to see snow-meltwater continue to flow in. As of 11 AM, they were letting out 65,029 CFS, but have a staggering inflow of 132,107 CFS, more than double the release rate:

oroville-in-vs-out-11am-2-10-17

Source: https://cdec.water.ca.gov/cgi-progs/queryF?ORO

What’s more worrying is this graph comparing the 1997/98 super El Niño year to this year:

oroville-storage

They’ve got a hockey-stick of storage going on, and much earlier in the water year than 1997/98…and they have a busted spillway.

We’ll update this story as more is known.

Here is a historical video for perspective:

UPDATE1: about an hour ago, officals say they “think” they can avoid the emergency spillway:

OROVILLE

With a break in the weather and increased outflow from Oroville Dam’s heavily damaged spillway, state officials said Friday morning they no longer believe the swollen reservoir will breach the dam’s emergency spillway.

After a grim assessment late Thursday, officials announced Friday morning they think they can avoid using the dam’s emergency spillway, which they’ve been working feverishly to avoid. The emergency structure feeds into an unlined ravine, and the water would propel soil, trees and other debris into the Feather River.

The announcement came after William Croyle, director of the state Department of Water Resources, told reporters Thursday evening that water levels in Lake Oroville could reach the brim sometime Saturday, forcing activation of the emergency spillway. The emergency system, which has never been used, would dump water onto an exposed hillside, dislodging trees and earthen debris into the Feather River and potentially affect communities downstream.

Read more here: http://www.sacbee.com/news/state/california/water-and-drought/article131743014.html#storylink=cpy

UPDATE2: 

As of 11PM on 2/10/17, Lake Oroville is now less than a foot from the top and overflow on to the emergency spillway.

 orovilleUpdate 3: Oroville water level tops 900 feet, water will start flowing down spillway
oroville900
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How about building Auburn Dam and a couple more large dams and not High-speed rail and more expensive renewable energy?

ShrNfr

You don’t understand. The problem with the spillway and the high reservoir is caused by climate change. It’s wurst than the thought.

West

Unless global warming causes poor maintenance, uh, no.

ShrNfr

@West, it causes everything bad, even everything wurster. If we do not act now, the children will not understand whatever happened yesterday. In this case it was rain. Tomorrow it might be sun. Who knows what it might be sunday?
All kidding aside, this is the extreme hazard presented by allocating funds to unicorn chases instead of resources that need tending.

usurbrain

THey have been assured for years that there would be no more rain. Thus why waste money on maintenance.

Caligula Jones

So….maybe should have spend a few $ on infrastructure instead of bankers, huh?
Who knew?

john

In Maine a gate failed at the Canada Falls dam and drained the lake earlier this year. It is owned by Brookfield in Canada. They are the folks buying Terraform Power and Terraform Global, which are yieldcos formed by First Wind and Sun Edison. Apparently they do not properly maintsin their real estate holdings very well…

Stewart Pid

Hell of a way to run a drought!!

Johannes Herbst

Not global warming causing poor maintenance but the “threat of global warming“, which siphons off all funds and intellectual energy for renewables and climate mitigation so the there’s nothing left for maintenance.

RayG

ShrNfr February 10, 2017 at 11:54 am Stop being such a brat.

Manfred

“Climate change” … really? What definition are you using?

Gunga Din

Sorry to disagree, ShrNfr.
It isn’t “Climate Change” (previously known as “Global Warming”) that has caused many such problems that we face today. It is the decades long obsession with it.

texasjimbrock

Wurst? Sausages? Or do you mean “worst”?

texasjimbrock,
Doesn’t make a dfference: worst is Dutch for sausage as is the German Wurst… Oh, the nice particularities of languages…

You haven’t learned anything about history, the biggest flood was in 1860s

Bryan A

It’s most unfortunate that they need to overuse the Spillway due to inflow rates and not hold off until a thorough investigation can be conducted to ascertain the cause of the failure. All they are accomplishing is to Wash Away and otherwise obliderate any possible evidence

MarkW

If the cause was poor maintenance, then the organization responsible is also the organization that is doing the washing away.

Bryan A

Must be “White Washing” the findings reoprt before the fact

george e. smith

How would you “maintain” some rebar filled concrete ??
I didn’t read “prestressed” in there anywhere.
Rebar filled concrete is just waiting to get bent so you can expose the iron to moisture to rust it away.
They didn’t even finish the “new” Bay Bridge before it started rotting away from rust, and when it fails they will be reminded that they were told that this was about the worst possible bridge design they could have placed in that location. The thing is holding itself up by it’s own shoe laces, and isn’t attached to anything solid that won’t move.
Well it’s kinda like the mine tailings filled bridge design.
I almost forgot. It has nice LED lighting, You need to have lights on a bridge so it makes colorful movies as it falls down in the next big earthquake.
g

D.I.

Bryan A,
you mean like this?

Bryan A

That water downstream looks exactly like my morning cuppa

jorgekafkazar

The cause is already abundantly clear. See the previous thread. “All” they’re accomplishing? You don’t know much about dams.

@George e.:
You find and seal the cracks in it (with slip or tar), and you can resurface it if needed. Find those places with subsurface soil erosion or collapse and fill with concrete. This can even be done with sinkholes. (I-4 in Orlando recently had a huge sinkhole filled that way).
The only hard bit is that you need to do this in the dry season when the spillway is unused… I.e. think ahead. Not something California goverment does well.
It looks to me like the failure was from soil erosion under the spillway then concrete collapse, not concrete collapse first. That could easily be seen and repaired if decent inspection were done.
IFF rebar failure gets bad enough, you remove and repour that section. Fairly easy on a preexisting footing in good weather. Hell to do with the soaked scoured mess they have now.

Bryan A

I’ll wager that the Mythbusters could fix the whole thing with Duct Tape
https://m.youtube.com/#/watch?v=FnILEXnRHP0

george e. smith

We can always use some of our surplus free clean green renewable non storable , use it or lose it energy, to pump more water out of the ground when we run out, next hundred year drought. That won’t happen till at least July 4 at the earliest.
You don’t really believe that California actually has a supply of grown ups, who manage the various resources of the sixth largest economy on the planet.
Maybe Elon Musk can morph the high speed rail into a high speed rail gun to lunch himself to Mars, to find us some pristine Martian H2O; excuse me there that’s “launch” not lunch !
Bitt of a guffaw there Mate
This is not even funny enough to qualify as a snafu.
This is the fourth running of the Jerry Brown Governorship cartoons.
Oh; I almost forgot; we’ll be seceding from you yanks anyhow, so we’ll just launch out into the wild black yonder.
I got a nice thank you note from the New NZ Prime Minister’s Office, so maybe it’s not too late to apologize for leaving.
Well but I really have become accustomed to this celluloid State, and its totally stupid Hollywood spokesfolks.
Even their fictition writers can’t make up stuff as good as this.
We’ll let y’alls know when to turn the lights back on again.
g

PiperPaul

Repurpose the tubes from Musk’s Hyperloop as emergency overflow piping! There, simples! Where’s my consulting check?

MarkW

“wild black yonder”
Is that a micro-aggression?

texasjimbrock

Sad to say, I have a grandson who resides in that yoyo of a state.

george e. smith

Why is it that so many readers here simply don’t understand that this “spillway” is not some structure sitting on solid ground.
It’s a thin film of concrete over chicken wire that is hanging up in the air.
It is NOT ….. PRESTRESSED CONCRETE …..
It has virtually zero bending strength. Just like ice, it breaks when you bend it, and you can’t glue it back together with some Elmers glue or a dash of tar .
Since the whole dam is just piled up dredging and mine tailings dirt, the material of the dam is not capable of supporting a flimsy sheet of driveway concrete.
So the entire spillway should have been built as a self supporting pre-stressed concrete rigid structure, with supports drilled down to bedrock.
It’s a total joke; well it’s also the tallest total joke in the entire United States.
G

Chris4692

Since the whole dam is just piled up dredging and mine tailings dirt, the material of the dam is not capable of supporting a flimsy sheet of driveway concrete.

The structure of the dam is earth-fill, and the electrical generation spillway goes under it. The two other spillways that run over the surface are on top of a natural hillside, not on top of fill. Design practice for earthen dams has always been to put emergency spillways on natural ground. If they did not have a natural area to run the emergency spillway they would have chosen a different site. If they did not have a natural surface to run the concrete spillway over the surface they would have constructed that spillway through a pipe under the fill, not on top.

Realist

While I agree with you about the fiasco that is High Speed Fail, you do realize that the Auburn Dam would have been upstream of Folsom Lake, not Lake Oroville, right?

Of course, I live in Sacramento!

Todd Brophy

Agree, agree, agree!

Aron Chigbrow

You are comparing the wrong water year. The 1997 flood event occurred in the 1996/1997 water year and not the 1997/1998 water year.

scraft1

Cool video. Most interesting. Thanks

Nice to see the REBAR jump-the-gun speculation diminish. This event is spectacular enough without all that.
With the weather apparently clearing for a few days, it looks like they’ll avoid having to allow runoff over the secondary emergency spillway, which has no concrete but huge boulders and PGE transmission lines crossing it.
Also – at a mtn bike forum linked at the previous Oroville thread, someone posted a photo of what they claimed looked to be inspection of a crack in the spillway from 2013 (you can also see the transmission lines).
http://fcdn.mtbr.com/attachments/california-norcal/1120603d1486695238-ot-oroville-reservoir-situation-16508579_1212016275513733_1512733581637597118_n.jpg

Greg

interesting comment. Those guys are not there to test the hill-climbing capabilities of their 4x4s.
I’ll bet a FOI request will reveal this has been known about for some time.
I agree with yesterday’s post that there was NO evidence of rebar visible in the photos. I get the impression that it was bedrock and the concrete was just there as infill to provide a flat spillway, not to provide structural force. That may have been a design error.

SC

That isn’t bedrock under the spillway or you wouldn’t see a 45 foot deep hole open up.
As long as the spillway above the current breach remains intact and doesn’t start collapsing into the hole below it should be clear sailing. If not then all bets are off.
If they choose to use the emergency spillway however they should first do an expedited and comprehensive environmental assessment first in case it may upset delta smelt habitat downstream.

The problem I had with the REBAR stuff was terms like “blatant lack of REBAR”.
Much better to just say “is there REBAR in this spillway, I don’t see any”.

jorgekafkazar

The high res photo linked to from the previous thread clearly showed rebar. So did the #3 photo in the previous thread when zoomed in on. Rebar is not some rare thing invented two weeks ago. It’s standard construction, and has been for a long, long, long time. A project this size would have had immense oversight and approval at several levels. “Forgetting” or deliberately omitting the rebar would not happen in this country, and probably not in most of the world.
The chance that bedrock that long would occur right were you want a spillway is zero.

george e. smith

You are joking; right ??
They actually plan to run water over that ski jump !
G

It looks like they are over halfway up. So I don’t think that’s where the failure occurred.

It looks like the same spot to me. Note location in comparison to the spillway slope transition.
http://cdn.kloveair1.com/art/news/2686.jpg

Bryan A

External erosion is clearly visible to the right and well above (30′) the point of failure

AP

There is groundwater leaking out of that crack. Hmmm.

AP

As I said yesterday, piping failure. See video.
https://youtu.be/AhpMyq4ZV2k

Through rock? C’mon … you do understand where the spillway runs, right?
We have ‘potential’ for this with the earthen dam at Lk. Lewisville (north and upstream of Dallas Texas) AND it is closely monitored …

george e. smith

Where these four trucks are sitting is precisely where the concrete bent and cracked; probably under the weight of those four trucks. There is NOTHING underneath supporting this thing.
And Dr. Roy should be blamed for the failure because his model of the great flood said it would overflow and it did.
You are not supposed to make computer models that describe something real, because then it might show people what really is what, and they don’t like that. Dr. Spencer should have described a spillway that rotated once a day, or something like that.
Any how Roy; you won the gold medal for getting the overflow automatic engagement of the emergency spillway system correct.
Just like you said, the water went right up to the top of the dam all the way along, and then it continued on over the top, completely untouched by human hands.
People should have listened to you and then done something to stop it reaching the top.
Maybe cut a hole in the middle of the dam to let all the water out of the lake.
g

Martin Moffit

Dam questions and dam answers about a dam problem. Thanks for posting the dam video. It was full of dam information. I feel dam informed. Hopefully they find a dam solution to this dam situation with the dam spillway.

Bryan A

Dam right

u.k.(us)

Dam nation

MarkW

Dam straight

Dam well said!

James Bull

Just don’t ask 617 Squadron of the RAF to take a look at your Dam problem they will make it go away.
James Bull

Don B

The 2011 flooding in Australia is instructive. Apparently conditioned to expect continuous drought, the managers of the Wivenhoe Reservoir allowed the reservoir to fill rapidly, and only released water when they feared the dam would fail. As a result, there was much destruction and some deaths in Brisbane.
http://rogerpielkejr.blogspot.com/2011/01/large-balls.html

Don B

Later, in 2011, the U.S. had its own Wivenhoe. Despite record snow and rapidly filling reservoirs, management of the water system waited until too late to begin releasing water, and so caused unnecessary flooding.
http://rogerpielkejr.blogspot.com/2011/07/american-wivenhoe.html

Chris4692

It wasn’t until very late in the snowfall season in 2011 that the accumulated snowfall in the watershed of the Missouri exceeded what had been seen in numerous years before. Then the basin was treated to rainfall that accelerated the melting of the snow pack. Within a short time of realizing that snow pack had accumulated to amounts they hadn’t seen before and before the rain, the Corps began increasing the outflow from the system, and notifying those downstream that more was to come. Within 30 days of accumulation exceeding the records, the Corps was using the channel to its maximum capacity at Sioux City, just downstream from the dams that control the system.
It wasn’t that the Corps was unaware or waited too long, it was that the event occurred late in the season and exceeded the flood of 1883 that was the basis of design. The reaction time reflected the time required for the data to be accumulated and analyzed, allowing for the natural “holy $h!t are you sure” reaction. There was just too damn much water.
In that 2011 event, the Corps could not have avoided the flooding. (I was engineer for a few of the cities downstream, which is why I kept track. I did create a computer model of flows and storage to keep track.) They could have shortened the flooding but only by using reservoir flood storage capacities into the following season, which was against established policy and would have left the basin vulnerable to flooding the following season. The Corps follows policy.

To the North, we had the same issue in the Souris-Assiniboine River systems in Northern ND and Manitoba in 2011. Heavy fall rains saturated the soil, heavy snowfall built up a massive spring melt, and then heavy spring rain topped everything off. It was a perfect storm for flooding, and it was massive. Land clearing and draining didn’t help as water retention on the land was/is greatly reduced. The bottom line, however, was simply way too much water.

Don B

Chris, thanks for your take on the situation. The newspaper article Pielke, Jr. referenced had a much different slant.

Pauly

The Australian situation is somewhat more complicated than that. The Wivenhoe Dam was designed as a flood mitigation dam, after the devastating 1974 floods in Brisbane. It has a rated capacity of 1,165,000 million litres (100%), but for flood mitigation, can add 1,450,000 million litres (225%).
It was to be complemented with a new dam south of the city of Brisbane intended to provide sufficient water storage for the growing population of south-east Queensland. However, construction of that new dam became a politicised issue in 1986, and no state government since has sought to build that dam. The consequence has been that the Wivenhoe Reservior now serves both purposes.
In 2011, south-east Queensland was just coming out of a 14 year drought, during which, water capacity had reduced to below 20%. While by law, water was to be released through the spillway within 7 days of reaching 100%, prior to the 2011 flood, water levels had been maintained at 109%.
As the following graphic shows, the other problem was that initial releases of water from Wivenhoe Dam did not match inflows, resulting in a massive increase in water levels, and then a massive release on 12 January which caused the flooding of Brisbane.
http://www.mdpi.com/2073-4441/3/4/1149/htm
However, after the flood damage became evident, water releases were rapidly scaled back, and the dam maintained dangerously high water levels for several days. At its peak, the capacity of the dam reached 193%, and water levels came to within 60cm of its emergency spillway. Perhaps it was just luck that no more significant rain fell in the catchment region for the next week.

Boyfromtottenham

Yes, Dan. As a brisbane resident I watched a similar graph go vertical showing the increasing water level on the Wivenhoe dam during that flood event. Unlike the Wivenhoe dam here, It looks like the Oroville dam doesn’t have control gates which allow water release during heavy inflows before the dam is under threat. Too bad for those downstream.

Snarling Dolphin

“…built in the 1960’s from clay and cobblestone recycled from an abandoned gold mine.” Yet another example of the folly of recycling. Good luck ya’ll. You’re gonna need it.

MarkW

It’s not the recycled materials that have failed.

NoFree Energy

I’ll bet there will be gold nuggets downstream after all this material is displaced.

Roy Spencer

I whipped up a quick little model that estimates the hourly change in lake level based upon the difference between hourly inflow and outflow rates. By extrapolating the observed downward trend in inflow, and assume outflow remains constant, I get overflow of the emergency spillway tomorrow morning….but just barely….peaking at less that 902 ft. (It overflows above 901 ft.) So, I see why they are now saying it might not overflow. Gonna be a full reservoir though!

SC

That’s good to hear because they seem to be awfully concerned about using the “emergency spillway” in this current emergency for some reason. Not that the main and emergency spillways being underlain by loose gravel, sand and rock nor the 770 foot high dam being composed of sand, gravel, rock tailings and clay itself could ever pose any problems since it’s global warming induced drought from here on in.
Otherwise they might want to rethink some design elements.

Joe Civis

Hi SC,
the emergency spillway is not so much a spillway as a lower spot in the wall that will allow water to over top before the water level gets high enough to compromise the dam itself. If the water flows over the emergency spillway those flow are completely uncontrolled and there may be problems further downstream not the least of which include all the additional debris in the water flow from the emergency spillway area and including the chance to take out the 230kV lines…..
Cheers!
Joe

Joe – While what you wrote is readily apparent now, I asked a similar question before it was so apparent and did not really get a good explanation. Yours was what I was looking for. I appreciate the explanation. The reason for the scrambling to avoid using the Emergency “Spillway” is very easily seen now.

SC

Hi Joe,
Just thinking that as long as the main spillway does not start collapsing upwards of the breech that they may wish to open the main spillway gates further since it is rated for a 250,000 cu feet second discharge capacity. There is going to be one heck of a lot of sediment washed downstream in any event.
https://en.wikipedia.org/wiki/Oroville_Dam

re: “they seem to be awfully concerned about using the “emergency spillway””
Yeah, as Joe points out it (the “emergency spillway”) simply prevents water from OVER-TOPPING the DAM which WOULD be catastrophic …

John Harmsworth

I see hockey sticks floating on your reservoir model.

Bob

Hey Roy,
.
Could I get those inflow numbers you used? I see the last single rain event raised the water from 848 to 901 in five days…. I’m trying to extrapolate the NEXT rain event looks like Thursday – Wed. If the dam only draws down to 860…. well. 910 will crush the ailing emergency weir in a few hours.

The damaged spillway seems to be defeating the avoidance of the Emergency Spillway. Might as well use the emergency one as the regular one will need to be rebuilt once the crises is over.

Roy Spencer

I think they are avoiding the emergency spillway at all costs because of the massive amount of erosion it will cause…they’d rather use the damaged concrete one. Gonna be a big hole left though, and the snowmelt hasn’t really gotten going yet.

Chris4692

They can modulate the damaged one, the emergency spillway is uncontrolled. Usually the emergency spillway is less protected from erosion. They are likely sacrificing the structure of the principal spillway for control, knowing more than we do about the underlying geology.

SC

Hopefully the downstream salmon are wearing goggles….

DonM

I don’t think the “emergency spillway” can be regulated in any way. Its better termed as emergency overflow, and configured only so as to not damage the dam itself.
Letting the water pile up to the emergency overflow level does not leave any ability to further manage outfall rates. IN = OUT; nature in complete control.

george e. smith

The 1953 Tangiwai disaster in NZ happened just after midnight on Christmas eve.
A giant ice dam collapsed on the glacier blocking the crater lake on Mt Ruapehu from exiting all at once down the Whangaehu river. The avalanche of ice and mud and volcanic boulders and trees all hit the railway bridge at Tangiwai , just as the midnight express from Wellington to Auckland was crossing the bridge.
The whole train and brideg, went in the river carrying almost 400 people to their deaths. Those who were found were full of glacial river silt. Most were never found.
It happened during a Royal Visit by the new QE-II, which really put a damper on things. They packed up the Royal Yacht and set off back home.
Turning a lot of water loose in a boulder filled gulley upstream of a river like the Feather river, is not going to create a lot of friends in the area.
Only in Dubai can you build your house on sand and get away with it. But I don’t think those clever Arab architects are using oil well drilling tailings to built their structural monsters.
Hopefully, Dubai is not a good location for free clean green renewable wind energy.
G

I don’t think the emergency spillway is controlled (I may be wrong). I think it’s a designed depression at the edge of the highwater level of the lake, so that if the lake surface gets to a certain level, that’s the spot it will overflow.

I understand that now. Thanks. I am learning a lot about Dams, and this one in particular.

Keith J

A similar event happened in 2002 at a central Texas flood control reservoir. Canyon Lake had been impounded in the early 1960s and never used the emergency spillway . The spillway was concrete lipped but the rest was a natural saddle draining back to the riverbed after several miles.
The flood of 2002 caused a rise to spillway elevation plus 7 feet. The 300 yard width of the spillway was designed to limit downstream flooding but the erosion products deposited in the river bed made floodgate operation impossible so all control was lost.
The same will happen here.

commieBob

The destroyed spillway is allowing plenty of erosion products to be gouged up. The river below is becoming so muddy that the salmon are endangered. If / when they have to use the emergency spillway the problem will be much worse. link

DonM

I wonder how much erosion/muddy water (and salmon harm) there would be if the full 135K cfs were passing the location of the dam. 🙂
And in the summer (without the dam), with some years of low to no flow …. historically, how did the salmon cope?
Dams are good.

They’ve been sucking up baby salmon at the downstream hatchery and hauling them away in tanker trucks to different locations for the past couple days.

beng135

Remember, the damaged spillway is caused by Trump & right-wingers. If only they had stopped using fossil fuels, it would never have happened….
/sarc for the clueless

ShrNfr

I sarcend that comment.

MarkW

Just don’t sarc-rifice that comment.

J Mac

Sarc-hasm…

It was during the huge rain of 1996/97 that Oroville Dam was almost over topped, not the winter of 1997/98. The winter of 1996/97 saw massive rains in Northern California, and in the winter after that was when Southern California received very heavy rains. I remember distinctly as it was a point of change in my life’s circumstances.

Quinn the Eskimo

This is a cool video on the use of the emergency spillway at the San Pedro Reservoir in California in January 1997.

Thanks Quinn. Interesting and informative vid. At the 26.30 mark ( and on) they showed a scoured out section of twin Gulch all the way back down to bare rock.( and other areas) I wonder if in their infinite wisdom they filled it back in so that with today’s excess of rain they’ have trees gravel and mud clog up down stream areas?

Archer

The make speaker has an amazing voice.
I want to rub that voice all over me.

We’er all goinna die! Aaaghhh

BallBounces

You’re all wet. On the other hand, if I’m wrong, you’re still all wet!

commieBob

It’s hard to avoid death. Just saying …

Bryan A

given the current rate of decay for the human body, would you really want to live for more than 120 years

george e. smith

They say the first person to live to 150, besides Methusalah, only has less than 100 years left.
And the first person to live to 1,000 has already been born.
I’m outa here before that.
g

MarkW

By the time you get to 1000, immortality is just around the corner.

I calculated once how long it would take the human body to soak up a fatal dose of radiation from just the background, given that dosages are cumulative over one’s lifetime. I think the answer was around 1200 years, certainly less than 2000.

MarkW

Your given, isn’t.
The body repairs damage as it occurs. So long as the rate of damage from the radiation does not exceed the bodies rate of repair, there is little problem.

The odd thing is how the spillway initially failed. It collapsed. There has to have been underlying structural support damage that went undetected/unrepaired. Simple cracking of the concrete slab would not matter because of the rebar. Only if the earth underneath the crack had significantly washed out would you get the apparent initial collapse. That is something readily detected by simple visual inspection, I would have thought. Now the turbulence will rip out everything below the initial failure, down to bedrock.

Bryan A

and any evidence will be washed away

sbaer

No spillway on God’s green earth could have stood up to that torrent of water. And who says the emergency release will hold up. I really fear for those down below. Don’t mess with Mother Nature. We are just ants going about our business.

re: “And who says the emergency release will hold up.”
Once the top soil (what little there is on a hill made of rock) is gone, what’s left will be ROCK. The problem is the ‘debris’ (trees and dirt) washed down into the river below as I understand it …
Please, correct me if I am wrong.

Greg

I would have thought it would be stripped back to bedrock before being filled with concrete. I would not want to rely on the structure integrity of earthfill under a spillway below a dam !

THEY did (see response below to George.)

george e. smith

Well you are supposed to clean out down to the bed rock before you start building; not after you have built your dam.
g

re: “clean out down to the bed rock”
THEY did (FOR the dam itself). Go watch the documentary (at the end of the other, initial, thread) …

Rogerdownunder

Exactly right. The clean “break” at the upper end of the failure suggest it is a construction joint. It appears the lower slab fell into an eroded cavity, perhaps initiated by water seeping in though the construction joint and/or the sides of the pour. The concrete does not appear to be structural, but a “slab on ground” skin to protect the underlying base – likely compacted rock, from erosion. Just guessin’ tho
BTW – OT if you’re reading about monster heat waves down here, no State capital is forecast to get any where near 40C in the coming week, most mid 20s – low 30s. Sure it’s hot inland but hey deserts get that way.

Since it’s not renewable energy, why don’t we stop filling the dam.

Chris4692

There is a generator in the dam, providing energy, likely now running at max capacity. It provides part of the outflow so that less goes over this structure. The outflow from the damaged spillway can be modulated, the outflow from the emergency spillway cannot. They are doing their best to avoid filling the reservoir and avoid causing flooding downstream. There’s too much water.

Sorry, I was being sarcastic. The current refusal to categorize hydro as renewable annoys me to no end.

philip horner

Debris in river backed up water to generator outlets so they are off now. Loss of 15000 acre feet hr and 860MWH

There should be some great recreational gold mining this coming summer in gold country.

Bryan A

Possibly even some good Recreational Vehicle mining

Eustace Cranch

OK, that’s just plain funny.

If this dam were to ever fail, then there would be a gold rush on the Feather River drainage such as hasn’t been seen for 130 years. In 1981 I dredged the Middle Fork Feather River and averaged close to 3 pennyweight per day. Seven years later I dredged the same spot just to gain understanding of how the river might replenish the gold. In 1988 I also averaged 3 pennyweight per day. I would love to get back in the river as I could supplement my SS for the year by dredging. I would no longer need foodstamps. I would have never filed for foodstamps, if dredging had not been made illegal.

MarkW

Dredging the lake would extend the life of the dam.

Roger Knights

MarkW February 10, 2017 at 1:36 pm
Dredging the lake would extend the life of the dam.

Therefore it would be opposed by the Green Machine.

george e. smith

I think it is a bit too late to talk of dam failure; This one has already failed.
Now they have to figure out how to get rid of all the remaining water and the mine tailings and get down to bed rock so they can built an adult dam instead of a toy one.
G

MarkW

The dam is undamaged. It’s the spillway that has problems.

That would be quite a project. On another note, next winter could well bring the main event of an even bigger series of storms than seen in this winter. It is hard to say at this point in time if this is the solar related cyclic flood pattern. The winters on either side of a PNW cyclic flood are also strong rainy winters. So this rain could be the runner up to the cyclic flood, or it could be the main event. If it is the main event, then I now have a clue as to when the next solar minimum will take place as well as knowing what winter the next cyclic flood will take place in.

If the dam failed Oroville would be wiped out. It’s the spillway that’s had the structural failure.

george e. smith

Without the spillway the dam is already damaged.
If the spillway really isn’t needed why did they build it to begin with ??
G

Jim Rose

The dam has not failed! Quit scaring people. If the dam were to go, it would take out all the communities in the lower Sacramento Valley including the state capitol Sacramento. About a million lives would be lost in case of a sudden, unexpected collapse.

george e. smith February 10, 2017 at 1:45 pm” “I think it is a bit too late to talk of dam failure; This one has already failed.
It seems to this engineer (although not a hydrologist) that ‘things’ are operating within spec, save for a wide ribbon of concrete that acts to duct ‘spillway’ water down a hill. AND, I suspect there is a helluva lot of ‘rock’ beneath the ‘thin’ veneer of soil on the hill (NOT the dam) down which the concrete ribbon runs.

Robertvd

“If the dam were to go, it would take out all the communities in the lower Sacramento Valley including the state capitol Sacramento.”
So let’s hope it’s earthquake proof when it is on maximum capacity.

Nothing is earthquake proof. However it was designed to survive a normal sized one. If an 8.5 or higher one hits, all bets are off.

BCBill

Hmmm, seems like climate modelling has exactly the same utility as economics in predicting, preparing for and avoiding catastrophic events- which is to say zero. Maybe it is wrong to blame it on climate modelling though. No climate modelling was needed to identify that New Orleans was at risk and still nothing was done. Ah ha, the real reason for CAGW, it is irreplaceable as a scapegoat for all administrative bungling. No wonder governments support it!

Bryan A

Well, at least no Climate Models were harmed by the breaking of the Spillway

Chris4692

This has nothing to do with climate modelling. The design was based on either the largest event known to have occurred, (as was done for the Missouri) or a statistical analysis of prior rainfall data.

MarkW

It was climate modeling that claimed that drought was a permanent feature of CA now. It could have led to a reluctance on the part of the operators to start releasing water earlier.

re: “This has nothing to do with climate modelling:
BUT – was maintenance deferred b/c ‘models’ showed rainfall would never ever be an issue again?
Just asking the question in light of what we may seem to know at this point …

george e. smith

Well it’s a lot easier to know you are up a creek when you are already under water.
Those French geniuses were really on to something in N’orllns.
I think they are the same folks that have already poured all of the concrete for ITER.
It’s a new approach to product design. First we’ll build a nice box to ship it in, and then we will see if we can make something to go inside the box; something useful like a fission power plant.
g

MarkW

The French Quarter is fine. It’s the rest of N’awlins that is sinking.

DonM

135k cfs in. 65k cfs out. Effective 70 cfs detained.
Imagine what the downstream river would have looked like @ 130 cfs w/o the dam. Dams are good.

DonM

…130K cfs

JohninRedding

With water quality being the latest environmental sin that threatens those working in the private sector, it will be interesting to see what the state’s water quality control board will say about another state agency’s MAJOR violation. There will be significant erosion of the native ground under the spillway. And before this is done there will be additional structural damage done to the concrete spillway chute. This will be a major black eye for DWR especially if it is established that the spillway was not adequately inspected when was last scheduled.

george e. smith

Well it obviously wasn’t properly inspected, while it was still on paper in a dam architect’s office.
G

Other factors you don’t consider are 1) workmanship and 2) age-related issues (e.g. erosion). Also, materials selection can be out the architectonics’s hands too.

There has been a lot of seismic activity under and around Oroville Dam since it was built because of the weight of the water it contains and also from the pressure forcing water into faults near it. It wouldn’t surprise me that the damage was caused by some unknown stress fractures in the spillway or from weaknesses in the ground supporting it because of past seismic activity.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0ahUKEwj50dbk_YjSAhUT9GMKHQyoAAAQFgglMAA&url=http%3A%2F%2Fwww.johnmartin.com%2Fearthquakes%2Feqpapers%2F00000052.htm&usg=AFQjCNFXZ8nR9ZEg8fiOFCv_rzrcUcddGg&sig2=feY7_7vTt3HfksPsx4IOkA
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwj50dbk_YjSAhUT9GMKHQyoAAAQFgguMAE&url=http%3A%2F%2Fwww.sacbee.com%2Fnews%2Flocal%2Fenvironment%2Farticle2584322.html&usg=AFQjCNHed0SEYB-K2rMizANic2klsj6Gng&sig2=ZnPu1KsRjcnzSH5ogVYOMg

Windsong

There are many reservoirs in Northern California, Shasta on the Sacramento River and Oroville on the Feather River, being the two biggest. Would California be in a scenario similar to the flood of 1862 without the reservoirs impounding massive amounts of runoff this year?

Rob

Excellent point. The original purpose of most dams was flood control. Water storage and energy generation are secondary purposes, which have now been elevated in importance – often meaning that the flood control aspect is now overlooked (see references above to Australia and US floods).

Chris4692

There has to have been underlying structural support damage that went undetected/unrepaired. Simple cracking of the concrete slab would not matter because of the rebar.

There was erosion damage to the base that caused the failure. How it happened is a matter for investigation, there are several routes that could have cascaded into that erosion damage to the base. Rebar in the slab is very unlikely to have affected any of those routes. The joints between the panels would have given way before the slabs cracked either with or without rebar.

resistance

Looks like the CA perma drought is coming along swimmingly.

@ resistance , to me it’s being hung out to dry.

Retired Kit P

I was stationed downstream of the Conowingo Dam during hurricane Agnes in 1972 when, all 53 floodgates were opened and explosives planted to blow a section of the wier and the Teton Dam in 1976 when it failed.
Nature can be very humbling.

Phil R

Heh, that’s funny. I must have followed you at that time, although at a much younger age. My dad grew up in Wilkes-Barre, PA (not Conowingo, but farther up the same river) and we used to go on vacation there every year to see has family (my grandparents, uncles, aunts and cousins), and we drove through Wilkes-Barre after the Agnes flood. In 1976, when I was a little older, (1976 0r 1977, can’t remember which year now), I went out west on vacation with some friends and we went by the Teton Dam. Also went through Big Thompson canyon in 1977, after the big flood in 1976.

Retired Kit P

My first commercial nuke was the startup of Susquehanna Steam Electric Station. The plant was built above US 12 rather than the initial location closer to the river because of the flood.
Years later I took a Environmental Geology Class that used this event to explain how we change things like 100 year floods by paving natural runoff. After I shared my personal experience for the first three case studies, I was asked to move to another state.

Considering the level of environmental ignorance in CA, I would not remotely be surprised of the environmental extremist crowd has been fighting any repairs or improvements of the dam. That is what they do.

Caligula Jones

Maybe they can print out a few million pages of “permanent drought” articles and use that to block the water.

Maybe Peter Gleick will come and stick his finger in the hole in the spillway.

Caligula Jones

I didn’t want to be accused of VER (Violent Eliminationist Rhetoric – mostly coming from the left these days anyway), but yes, having a few dozen CAGW folks linking arm to arm across the hole did come to mind as well.

Rob Dawg

So we electric customers can expect a check instead of a bill this month right? So we water customers can expect a check instead of a bill this month right? The carbon taxes will be suspended?

WR

What was the cause of the earth underneath the spillway being compromised? Hopefully not seepage from the dam.

george e. smith

Earth is already compromised by definition. If it wasn’t earth it could have been granite. That’s nearly as good as bed rock.
g

JCalvertN(UK)

I have a book which contains a photograph that is captioned “Fixing the reinforcing steel on the spillway of Dibbis Dam, Iraq.” The steeply sloping slab in the picture is 7 to 8 feet thick between the top and bottom rebar mats. This is in contrast with the concrete slabway slab at Oroville which seems to be hardly more than 1 foot thick.
So I’m wondering if the problem is more basic than ‘not enough rebar’. I suspect it may be more like a case of ‘not enough concrete’.
For as long as a spillway slab can act like a ‘freeway for water’ (i.e. with water flowing on top and the underside kept dry) it only needs to be as thick as a freeway slab. But any water which manages to permeate *under* the slab high up the spillway could become highly pressurised lower down and ‘blow’ the slab off its substrate. Prevention of this from happening would require either a) some very clever and expensive pressure relief drains or b) a very heavy slab.

edi malinaric

I find it a little worrying when I hear all those officials talking as though they have any say about the control/use of the emergency spillway.
When one designs a dam wall -, say for a water level of 904 feet – you leave a section of the wall at 904′ and raise the remainder of the wall a metre or so higher. This means that you have a some say as to where the dam will overflow and that is all.
When the water level reaches 904′ the water spills over and away. No official has any control in the matter.
The water will continue to discharge down the emergency spillway until the water level drops to 904′ and then miraculously stop.
I guess the public mustn’t be alarmed.

SC

“No official has any control in the matter.”
Never say an official has “no control” or they may decide to start sandbagging the emergency spillway.

If anything exhibits a fat tails distribution it’s weather .

oo bad that california has not had any droughts lately so they could do preventive maintence — oh right — they need the money to support their illegals population

MarkW

and trains to nowhere

Don Penim

The California Department of Water Resources has a Twitter Page where you can get updates, photos, press releases etc. about the Oroville Dam situation.
https://twitter.com/CA_DWR

They have renamed it, it is now the Auxilliary Spillway no longer an Emergency

Here is something that undoubtedly added to this problem, “…The most recent inspection of the Oroville Dam spillway did not include a close examination of the discharge channel, according to a state dam safety report…” That is an excerpt from here, …http://www.redding.com/story/news/2017/02/09/dam-spillway-checked-distance-last-inspection/97723936/

Nice catch and thank you for posting. Using your info I went digging a little deeper and found this page:
Oroville Facilities – Project No. 2100
http://www.water.ca.gov/hlpco/p2100.cfm
Notable: “DWR anticipates that FERC will issue a new license order in 2017 pending issuance of the aquatic biological opinion from the National Marine Fisheries Service.”
Brief summary of facilities:
Oroville Dam is the tallest earth-fill dam, at 770-feet, in the United States and forms Oroville Lake with a capacity of 3.5 million acre-feet (California’s second largest reservoir). The facilities generate 762 megawatts (MW) of hydropower and provide storage to deliver water to areas of need. The spillway, located on the right abutment of the dam, has two separate elements: a controlled gated outlet and an emergency uncontrolled spillway designed to convey excess water over the spillway weir and down the undeveloped canyon slope to the river.
Edward Hyatt Powerplant has six generators (three for reversible pumpback operation), and a capacity of approximately 645 MW. In the bedrock beneath Oroville Dam, a cavern -large enough to hold almost two football fields- was blasted out to house Edward Hyatt Powerplant.

Alan Robertson

This is a perilous way to go about it, but all river systems need a good flushing every now and then.

W. Johnson

With regard to the damaged Oroville Dam spillway: the initial fissure that opened in the spillway surface was initiated by hydraulic pressure being built up/exerted within a void in the soil substructure under the spillway floor. Any expanding pocket (void) was excavated by venturi effect from the water flowing over the joint(s) of the concrete slabs (similar to the principle of how a suction dredge functions in gold mining). At a certain critical point the this void pressurized sufficiently to “lift” an edge of the slab by some increment. As this lifting occurs, the water flowing over the slab structure from continuing releases, increases the pressure within the joint of the incrementally “lifted” slab, and the pressure within the void in the sub soils below spillway. This process continues to incrementally force the section(s) of concrete apart/up to a point that the actual velocity and mass of the surface water flowing down the spillway can exert force on the now lifted edge of the concrete. It is at this point that the failure viewed in the videos becomes obvious as “chunks” of concrete etc. in the spillway.

DonM

I was guessing slow positive pressure subsurface loses rather than negative pressure surface migration, with water getting in from somewhere uphill/cross slope. Hard to tell, but it appears in the photos that there was a good gunite type seal/base under the concrete….

stan stendera

+1000

Myron Mesecke

I remember in 1992 when Belton Lake (Belton, TX) crested its spillway. It was very impressive to see what water can do when it isn’t controlled.
Going to be dangerous for any activity in the water downstream of Lake Oroville. Slabs of concrete and a rats nest of rebar.
Using Google maps there is a second dam or a set of gates just downstream. All that concrete and rebar will be fun to clean up when it bunches up there.

Downstream are the forebay and afterbay used to solar warm the water for rice farming. When the dam was built, rice farmers pointed out the cold snowmelt from the lake bottom layers, would kill the rice, so that feature was added. There is a slow section of river from below the dam to the forebay. Any junk will settle out there.
How do I know? About 1969 or 70 a couple of us kids built a raft and put it in at Oroville, then took a couple of days to go 12 land miles downstream. There are gates to control water in and out of the bays while the main channel still has a bypass if desired
FWIW, I watched the dam be built and attended the dedication.
The dam is fine. The spillway is well removed from it. It has served well for over 45 years so not a design fault. Just regular aging with insufficient maintenance and inspections. It would not have been hard at all to have even done a full remove and repour had inspection shown it needed. They just didn’t look hard enough to find the issues building up. Heck, they could even have concrete lined the Emergency Spillway over that 45 years had anyone cared.
Would I rebuild it stonger? Sure, but I’m prone to overdesign. Heck, I’d even use basalt rebar to eliminate corrosion concerns:
https://chiefio.wordpress.com/2014/12/21/unlimiting-resources-basalt-for-a-high-tech-stone-age/
Yes, it exists…
The dam itself has a giant concrete footer to anchor it to the bedrock, then a topper of clay in the middle (to block water flow) and gravel / dirt mix for the bulk of the mass (all heavily compacted by big roller trucks) then boulders and rock riprap facing. At least, that’s what I remember from watching it be built over several years. They used a giant bucket wheel digger to dig up dredger tailings for much of it. We used to go shooting and fishing in the resultant flat depression about 8? Miles downstream. Last time I visited, the State had posted that area off limits. Too many folks enjoying themselves…
I watched the first test of the spillway a few years later. Spectacular show as the water hit the teeth at the bottom (to prevent erosion of the opposite bank). At that time the highway on the other side was important… don’t know about now (I think they added a back road in). I’d be worried that uncontrolled flow will wash out the other bank and road… or that loss of the tooth section will cause the same.

Joe Ebeni

Hello Mr. Smith.
You seem to know more than a lot of posters here. I posted this as another reply so it is probably lost in action. I’m not an engineer, so a question. Why does a spillway need such a long run over a “ramp” that is built over fill? I assume the top of the spillway and associated gates are built into the bedrock. Couldn’t the spillway be a shorter concrete “cap”, with no long concrete run at all? Downstream flow would just run over bedrock.
Thanks in advance for any response.

You must get water from near the top, to the bottom. The geography sets the available slope choices and then that determines the design. The ground is typically not smooth rock of the right slope, so you put a slab over it (to avoid manual excavation or uncontrolled scour as is happening now…)
While the base is rock, under the dirt, it is jagged and irregular. As all engineering is compromise and money not unlimited, it is far cheaper and generally just as good to lay a well footed and reinforced slab over compacted base (with drains as needed). The alternative, excavation to jagged rock, then deep pouring brings in heat of cure removal and reinforcing design issues (how to form rebar over irregular rocks?) Or blasting to resurface (and crack base?…) issues.
The problem here was unlikely to be design. It has worked well for almost 1/2 century. I watched the first test of it with big flows and it was fine. What failed was inspection and repair to spec. That would not be fixed by more concrete.
To the extent any design improvement could be done, I’d speculate added sub-panel drains with sensors (that they didn’t have in the vacuum tube era when this was first designed…) would have assisted in inspection and detection along with removal of sub-panel pressurized water (if any). Then again, ground penetrating radar and sonar would likely have found issues too, if deployed IMHO.
FWIW one could install penstocks and gates like for the generator room, and avoid slope, but the cost is horrific (especially in the pre tunnel-boring machine era when this was built.). Also, failure modes are more spectacular and repair is done by draining the lake… some of the smaller dams here work that way.

@Joe:
The short answer is “yes you can” and that is how the “Emergency spillway” is built. The problem is the debris accumulating at the bottom from the scour of the rock. That has caused water backup to the powerhouse, so it is now shut down to protect it… Eventually you would get all the debris washed out, but it’s better to just put a slab in.

Michael Jankowski

Why worry about aging and crumbling infrastructure today when you can worry about a degree or two of warming 100 years from now?

RayG

Just think, in another seven years or so we can all drive to the Central Valley and ride all 32 miles of the California Bullet Train. Who needs to fix the pot holes in our freeways or, God forbid, build more surface storage.

Jim berryi

It would seem prudent to use the emergency spillway now at a moderate flow , which in combination with the damaged spillway will provide a larger margin of safety that they won’t have to discharge a large volume of water thru the emergency spillway .

Greg Strebel

Typically you do not have a choice about “using” the emergency spillway. In the absence of sandbagging, it will automatically start discharging water when it is overtopped. This is to prevent overtopping of the main structure which would undergo catastrophic erosion and a ‘pulse’ of flow an order of magnitude greater than the volume flowing into the reservoir, until the reservoir is essentially completely drained.

deebodk

The emergency spillway has no flow control. Once the water level reaches that height it’s going over.

F. Ross

They probably used FUBAR instead of REBAR in the spillway construction.

Jim berryi

This would be s good time to be thinking about “what’s the worst thing that can happen ” and act accordingly.

re: “the worst thing that can happen”
No “fish” available during Lent on Fridays? Sorry, had to do it.

No “fish” available during Lent on Fridays?

Let them eat Tofu.

Design standards from USBR, for dam spillways. Includes photos and diagrams.
https://www.usbr.gov/tsc/techreferences/designstandards-datacollectionguides/finalds-pdfs/DS14-1.pdf

Bill Illis

Good thing the GFS weather model forecast says only 12 inches of rain in the next two weeks.
http://www.tropicaltidbits.com/analysis/models/gfs/2017021018/gfs_apcpn_us_48.png

Mr. Wonderful

Mr Bill;
wow, that is a very interesting prognostic website.
I was able to recreate your pix with only minor flogging.
Those dam engineers had better get those lake levels down promptly, even if the precip will be less than another foot.
The peak discharge I saw was 275 kcf/second at the Yolo Bypass above Rio Vista.
Regarding spillway engineering, I wonder about the slope of the gated spillway.
From the pictures, I thought I saw a step-change in the slope, becoming steeper about 1/4 or 1/3 of the way down. I recall reading about other spillway failures that involve a ‘hydraulic skip’ ,where the water stream departs from the surface and then reimpinges.
That story about need to re-engineer the Glen Canyon overflow system struck a note for me. I suggest that operating for extended periods at a particular spill rate might tend to exacerbate issues at certain places along the spillway. Perhaps they need to slowly modulate the spill rate to avoid sitting on a particular ‘resonance’ , by ‘spreading’ the ‘sprectrum’ of the purported ‘rumble’ phenomena. The allocation of ‘spill rates’ looks rather linear and static, if recent release history is representative.

tomholsinger

I propose a pool on just when a newly eroded ravine in the Oroville Dam emergency spillway starts uncontrollable massive draining of the reservoir. And I choose Sunday, February 25.
Jim Berryi,
The worst case is that downstream levies around the river side of floodplains north of Sacramento are breached. There are 100,000+ homes in the Natomas floodplain alone.
http://www.sacbee.com/opinion/op-ed/article2604482.html

Before that, it will breach about 12 miles downstream and flood into the central valley there. In about 1960? I went to the river with my Dad to see when we would flood. (North of Sacramento about 70 miles) At that tine, 1/2 of the bridge had washed out and we were about 2 feet from the levy tops. This was part of why they built the dam.
My home town has curbs about 2 to 2.5 feet high with a step in them. In the 1800s they raised the whole town two feet as that was the usual flood level. In winter, the streets become large drains… this is 4 miles from the levy… 32 foot elevation over about 210 miles to the SF Bay…
Sacramento tends to flood when the American River has excess water or the Sacramento River (Lake Shasta) has issues, while the Feather hits Marysville and north. Spread it out 2 feet deep over 30 miles wide and 200 to the bay, it holds a lot of water.
So that’s why we went to see how soon to plan on staying in the house if the river overtopped… Needless to say no flood improvements have been made since the dam was built.
IIRC, flow rate was about the present inflow rate to the lake now…and flood would happen at something like 150k? Hey, it was a long time ago…

philip horner

Well here it is Fed 12 and the dams are full everywhere. Essentially, there is nothing left for flood control in the North State.Rain will start again in just 5 days. The 50′ lake level margin for flood control was lost in a few days during the rains as the spillway broke. Now the dam needs protection from overtopping. A big storm + perhaps some wave action can overtop the dam. Lake is now 1.55 feet HIGHER than the emergency overflow….I do not know how much freeboard is left on the dam itself. This is a very precarious situation. Rain can still wreck this dam. That emergency overflow can’t ship enough water. The prudent thing is to build TWO spillways. 330000 acrefeet is the historic max inflow. Spillway is good for 150000 AF. Is my math wrong or is this thing undersized?

Philip,
Each spillway is good for somewhere near 250,000 cfs. The Emergency spillway alone is sufficient to prevent overtopping as the lake buffers inflows so you never need the peak inflow. Besides, at about 150,000 cfs my old home town gets flooded out anyway…. the goal is to stay under that via consistent 55,000 cfs from the damaged spillway.

Mr. Wonderful

If I am calculating correctly, a net 50kcf/second will remove 100TAF (100,000 acre-feet) of water per day of that net outflow. (actual outflow – actual inflow)
As of midnight on Feb 11, Oroville shows 790TAF of ‘encroachment’ above the ‘Top Of Conservation pool’. I don’t see how they could get Oroville down to TOC conditions before the next set of storms. (Top Of Conservation is apparently a seasonally dynamic value, and perhaps weather-dependent?)
As far as I can tell, the DWR engineers have a difficult dilemma;
Door#1 Operate the gated spillway at high flows and destroy it, and possibly silt in the generators
Door#2 Continue with less than 50kcf/sec net outflow, and risk uncontrolled releases from the ’emergency spillway’, apparently recently renamed by the PR department.
Have I miscalculated the situation? That 10 day forecast of precipitation from GFS that Bill Illis shared, shows quite a lot of precip in the watershed, unless I misread the geography as well. Maybe it will all be the lovely solid version of global warming.
I still miss your graphs with hair.

HalfEmpty

Thurber was a veteran of this flavor of disaster, from the front.
http://downwithtyranny.blogspot.nl/2011/01/thurber-tonight-my-life-and-hard-times_09.html

Greg Strebel

Echoing DonM’s remarks. In the absence of the dam, the river downstream would already have been flowing at up to nearly 180,000 cfs per the reported measure at the top of the table in the article. Salmon had to survive (or not) that flow rate on occasion in the past. Should the emergency overflow level be overtopped, there could be unusual local erosion in the emergency spillway, with detrimental effects downstream, but these pale in significance compared to dam failure.

Steve Lohr

I skimmed the Division of Water Resources page. My immediate impression is that PR over substance seems to dominate. I think the term flood is appropriate. If the upper river wasn’t flooding the dam wouldn’t be close to over topping. Damage was revealed when the spillway HAD to be used because there is too much water behind the dam. And, as was said above, there is no choice to use or not use the emergency spill way. That will happen when the “flood” is great enough to do so. Any impression that they have control is a function of the remaining time before the water reaches the emergency spillway. Which is running out faster than the water.

You expand capacity and maintain dams and reservoirs during drought when work is inexpensive, easier and will be easier to compress or cure. But not in CA. Not an acre foot of capacity or upgrades done during 10 years of drought. Unbelievable. A reflection of liberal thinking. The religion of global warming made it easy to ignore these problems.

Akatsukami

It’s the hillbilly mindset: “When it ain’t rainin’, don’t need ta fix it; when it’s rainin’, cain’t fix it nohow”.

Kalifornia Kook

Oh, we did do something. We passed a proposition that funded $7 billion for new dams and repairs. Oh, wait… if you actually read the proposition, it allocated money for dam removal, funds for disadvantaged communities, and ‘studies’ for future dams. After the Sierra Club obstructed the Melones Reservoir in the mid-70,s, there ain’t gonna be any new dams here until their teeth are pulled, and that ain’t happening in Kalifornia. We are too leftist to allow that.

Gunga Din

Not an expert’s comment:
Who has looked at the “as built” blueprints? As, I’m sure others have said, the straight line breaks all appear to be along the seams of the expansion joints. Did water seep in from neglected expansion joints?
Under Governor Moon Beam, was the money to maintain what exist neglected in favor of windmills and sunbeams?
Just questions. I don’t know the answers.
But, if we don’t maintain what we have, “California Dreamin'” will only end in a nightmare.

Brad

Yep: Moonbeam was busy buying sun beams and the dam built by the world’s greatest engineers was simply allowed to rot away.

Here is a short video of the building of the dam. Reagan makes an appearance at the dedication, …https://www.youtube.com/watch?v=p_5udzKfLQM#t=340.776053

Yes … as posted in the previews thread; proper credit and title: “The Birth of Oroville Dam” – produced and directed by Mark S Lambert

I was there too! See that teenager in about the 10th row toward the center right? 🙂 ….

AP

Good point

1saveenergy

Similar design of earth dam over-topped in semi rural Yorkshire – Dale Dyke Dam 153 yrs ago.
https://blog.geolsoc.org.uk/2014/03/11/the-great-sheffield-flood-of-1864/
sod the fish, they need to spill