Scott Cahill: Collapse Risk At The Oroville Dam Is Still Unacceptably High

Tyler Durden's picture

Authored by Adam Taggart via,

Remember the crisis earlier this year at the Oroville Dam?

The overflow from California's winter of heavy rain threatened to overpower our country's tallest dam. A cascading failure of the dam's main gates, its primarily spillway AND its emergency spillway had the world watching hour by hour to see if a catastrophic breach was going to occur.

Fortunately, the rains stopped long enough for the situation to be brought under control. The dam remains in place and repair crews have been working all spring and summer.

But should we breathe easy at this point? Not at all, says dam safety expert Scott Cahill. Our readers will remember Scott from the excellent technical assessment he provided in the thick of the crisis earlier this year. In our earlier podcast with him, he explained how the real tragedy at Oroville was that for many years, small and affordable maintenance projects that easily could have prevented the crisis were diverted (in his estimation, the cost of making the needed repairs was quite small -- around $6 million. But for short-sighted reasons, the repairs were not funded; and now the bill to fix the resultant damage will likely be on the order of magnitude of over $200 million. Which does not factor in the environmental carnage caused by flooding downstream ecosystems with high-sediment water or the costs involved with evacuating the 200,000 residents living nearby the dam).

And the pattern appears to be continuing. In this week's podcast, Scott details a number of concerning structural risks visible at Oroville that are again being de-prioritized, or ignored all-together. And as before, straightforward and inexpensive projects that have high potential to prevent a catastrophic failure of the dam are not being pursued:

They've begun the repairs on the bottom half of the spillway, but the tragedy and loss from the bottom half of the spillway failing has already been realized. No one is worried about the bottom half of the spillway. On the other hand, they've done nothing yet with the upper half of the spillway -- which is what would cause a catastrophic failure of the dam. It's amazing how much money they've already spent, and yet their priorities are such that they haven't abated the liability at all.


So yes, we've made the bottom of the principal spillway, the concrete slues, more sound. But it's not the bottom of the dam that will fail, of course, it's the crest -- the top of it -- where the gates are. That's still highly suspect.


There are additional issues involving the unwanted moving of water through the dam -- the so-called "green spots". These are areas where water is migrating through the dam, probably through the indigenous soils adjacent to it. I've walked on these [at Oroville] and you can stick your foot down, and like your backyard after a torrential rain, water actually comes up into the footprint after you remove your foot. This is not a good situation. I believe there is a lot of movement of water through that dam, including at the structure itself that houses the gates that control the flow down the principal spillway.


There's nothing wrong with embankment dams in general, they're wonderful dams. But they rely on the mass of the earthen embankment itself to offset the forces that try to slide or rotate it into failure. When we see water migrating through a dam, it can potentially cause failure of the dam because it offsets the mass all that earth. Plus, there's a lot of river rock and sand in this embankment. River rock, as we all know, is round. Anyone can understand how a pile of round rocks, if the fines have been washed out from between them by water and the rocks then vibrated, for instance, by seismic activity, weakens the system. These concerns are very, very serious. I believe that this situation is occurring in multiple places across the Oroville dam -- and yet this is simply not being discussed.

Click the play button below to listen to Chris' interview with Scott Cahill (41m:06s).

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peddling-fiction's picture

Pull it, governor moonchild, er, moonbeam.

Beam Me Up Scotty's picture

"in his estimation, the cost of making the needed repairs was quite small -- around $6 million."

Isn't this about the same relatively small cost that it would take to harden our electrical grid against a solar flare or EMP??  Shovel ready jobs!!!

847328_3527's picture

He didn't mention how many smelt were loss in this tragedy.


I'm disappointed.

Swampster's picture

I have maintained all along that the crisis  was not over.....


and NO, I did not stay at a Holiday Inn last night, but I am a Fluvial Geomorphologist, Hydrologist, Riverine, Riparian, Littoral, Hydraulics Specialist, and a Licensed P.E.



but what the fuck do I know!

Cognitive Dissonance's picture

I love it when you talk like that.

Say it again, but this time with feeling. ;-)

Stuck on Zero's picture

I love this part:

... environmental carnage caused by flooding downstream ecosystems with high-sediment water or the costs involved with evacuating the 200,000 residents living nearby the dam).

And what was going on for the previous million years before the dam was built?


DWD-MOVIE's picture

I’m making over $7k a month working part time. I kept hearing other people tell me how much money they can make online so I decided to look into it. Well, it was all true and has totally changed my life. This is what I do…

Rabidcephalopod's picture

If they've got several zones of saturated soils on the downstream face, they've got problems - not to mention the spots around the gate structures. A little differential settlement there, and potentially they're inoperable.

youngman's picture

I bet you are fun at cocktail parties

Implied Violins's picture

He'd make one heck of a great bartender, what with that fluid science background. Probably gets the best babes, too.

swmnguy's picture

If I understand you correctly, you're saying the shit's all fucked up?

garcam123's picture

If you are all that learned, most esteemed regards..Having been a structural concrete and waterproofing manager foir years.....Why wouldn't a geotextile fabric anchopred into the earthen bank provide additional swcurity and stop the through-flow at the face?


Thanks for your thoughts........

just the tip's picture

for starters, it's a question, and second, you should know to stay at a Holiday Inn Express.

drendebe10's picture

Dollars to donuts the azzwipe bureaucratic turds will fire him. 

Government is not the solution to our problem. Government is the problem.  R.Reagan

gdogus erectus's picture

Hi Swampster,

What was that geologist hangout site that we were all hooked on back then?

CrazyCooter's picture

Just helping the lazy ZH'er kids on my lawn these days ...

Fluvial Geomorphologist



Hydraulics Specialist

Licensed P.E (physical educator)



stitch-rock's picture

doomporn clickbait gettin a lil better...

c2nnib2l's picture

though this article was about the stock market 

peddling-fiction's picture

Metaphorically it is, it is, oh my...

cougar_w's picture

This guy doesn't get it. The dam spillway failed due to cavitation, associated with heavy volumes of water at speed. Only the bottom part would be expected to collapsed under that kind of assault. The rest of the dam was never under any kind of stress; the gates are fine. However the secondary spillway is still useless, but the only reason they leaned on the secondary was because the primary had already broken. If they can fix the primary maybe they can stay out of the secondary. If they start to over-top again they'll be back in the secondary, and using the secondary was why they evacuated the city below the dam; the secondary is crap, stupid design doomed to fail if ever used. Breaking the primary put them into the secondary (never happened before) and the whole shit-show fell apart within hours.

nmewn's picture

Do they have warrants out for the water scavengers yet or are they looking the other way until the next drought? ;-)

cougar_w's picture

I think they've relaxed a little. Bigger issue now is developers have used the lean water years to "discover" new places to build homes -- places the Olde Timers would tell you can flood at the drop of a hat. So now all these people are hoping it doesn't rain so their homes don't flood. Stupid. The county took the bribes to open up development in flood plains, the developers built the homes and skipped town. Now the taxpayers get to clean up these places prone to floods. I hope they get flooded out and those lands turn back into wetlands again, let the county explain all that to people.

nmewn's picture

So the obverse of Florida swampland drainage & development then. 

Be a great place for unbribed, truly altruistic politicans & regulators to make a living then wouldn't it?

Of course, its granted there are such people ;-)

peddling-fiction's picture

Aaaah, unspoiled and charitable politicians and regulators... ...snapping out of a day-dream...

garcam123's picture

Isn't that what the phrase from 2500 years ago, "cavate emptor" or something,,,,It's

AH there it is!..............If you bend over, even for a second, they will drive it right up your asshole, no matter how innocent you are, right up to your tonsels.

It's called "Law enforcement", but it's really legal murder by the criminals with the guns and blue shirts

That is the main problem in the world today.......fuck a bunch of climate change.....everybody has a sore asshole from the fucking we've been taking from our "leaders".



Pernicious Gold Phallusy's picture

Roger that. Over the years I've occasionally driven on 70 between Sacramento and Marysville. It crosses low rice and fruit farmland, the road elevated on a dike part of the way, to keep it open during flooding. Once I was amazed to find dozens of new houses at a spot where 70 would be closed frequently due to flooding. I would guess those houses would get at least 4 feet of water on a regular basis.

Farmerz's picture

The water there was up to the second floor  during the Jan 97 flood.

Flocking swans's picture

You are talking about Plumas Lake (track home hell)- 12,000 homes 'planned' there.
Named after the lake! that used to occupy the area...
In 1986&1997 under 15-20 feet of water...
But the superwalmart in olivehurst* has pool noodles on sale!
* olivehurst might be why dog invented floods...

NoPension's picture

I've been following this via a YouTube channel since it started.

The job Kiewit is doing, and the setup they have out there is mighty impressive.
I build for a living...using the same materials. And watching the scale of what they are doing...and the speed at which they are doing it...I'm in awe.

cougar_w's picture

Yeah looks good doesn't it. Probably costing 200x what it did originally due to the haste. And given the haste you have to wonder what new corners are being cut this time around. DWR are pukes, they work for the South State you can't trust them. I wouldn't be all too surprised if the primary fails first time in use and they are right back where they started.

Archibald Buttle's picture

call the FED. you've found the inflation they've looking for so desperatly lo these many years!

the piper's picture

Same here.  I regularly tune in to Juan Browne over at the blancolirio channel on YT.  That guy is as dialed in on this project as anyone in the state, and If there was anything amiss, he would have caught it.

cougar_w's picture

Juan has been spot-on. Best reporting on the failure and mitigation, IMO. Not that he would have caught everything underhanded DWR might have pulled in the haste to get it done for the visuals of everyone watching them cleanup the primary after their fuckup concerning the secondary spillway.

Incorporated by inference's picture

JUAN is top notch. Sometimes he can report a little fast. Check out this guy.

I can't put my finger on the background noise I think it might be free range chickens.

cougar_w's picture

Interesting. Well it's an earthen dam, I don't think they did anything in the original design to stop seepage. Makes you wonder if there is an internal failure made evident by the high water level. If there was they wouldn't tell anyone, fact. DWR are self serving whores to rich ag interests, they don't give a shit about anyone living in Oroville.

malek's picture

You're talking nonsense.

So what now,
is the secondary spillway useless but unimportant,
or part of a sound overall emergency concept but being ignored before and now?

And if the bottom part of the primary spillway collapses as it did, how do you know (except in hindsight from ONE occurrence) that the top part is not impacted at all.

Pernicious Gold Phallusy's picture

The secondary spillway has a thin concrete lip at the top, then bare dirt down to the river. Anybody who's watered a garden with a hose could see overtopping water would rip out the slope and undermine the concrete lip. With the lip gone the ever-increasing flow would cut straight down the face of the dam to the bottom of the reservoir in no time. Nobody would get out.

junction's picture

I am waiting for the Drudge Report to have the following banner headline: THE DAM'S BUSTED!

nmewn's picture

Wait, Oroville Dam is in Kalifornia.

Wasn't Obammy out there a couple years ago proclaiming doom & gloom for-evah over another friggin drought in the SW unless the masses endorsed the NWO's world taxation schemes? 

I sure hope the "natives" are collecting the excess water "gaia" has provided for leaner times, unless its against "mans law" and illegal or sumpin ;-)

cougar_w's picture

All the reservoirs are topped off, if that answers your question. Filling the reservoirs after years of drought was the only thing saved us from drowning, and even then we had a lot of unexpected flooding late in the season. If we get another heavy rain year we are absolutely blown, place will look like any part of the SE the last year or two. 

nmewn's picture

Well, my point was O'Bammy and his particular brand of NWO bullshit poli-sci but...I do hope you guys don't get slammed again. 

Its just the nature of that part of the country, breath taking beauty when it rains and barren dryness when it doesn't. 

Is what it is.

cougar_w's picture

Yup. People used to respect "what it is" and stay out of the way of nature. But the value of Cali land being what it became, counties were looking at low-lands and saying "that's property taxes we're not collecting" so they developed it up. Got their loot and skipped. While it didn't rain, people liked it. When the rains came, they were all "oh no what is this happening". Yeah stupid bitch you built your McMansion in a flood plain. Nature wants it back for the ducks and geese, thanks. Now suck on it. 

Archibald Buttle's picture

can't they just build some tunnels to take this excess water to where it's needed more? (/s) it's california after all, so it will be a cinch to enact a new tax to "pay" for it. (no /s, unfortunately).

staying out of the way of nature, and learning to work with it is the most prudent plan. alas, i fear that ship sailed long ago, and the good captain has failed to spot the iceberg dead ahead. so it goes...

Synoia's picture

Dams are temporary structures. Basic Civil Engineering.

The weight of water deforms the land under and to the sides of the dam.

A lack of Maintneance? The anti-tax prop 13 mind-ser at work.

This is what you get when you don't fund the commons.

Mr. Universe's picture

Yes just what we need in Taxifornia, more disasters in order to extract moar taxes. Just like the latest gas/car reg tax increase, you know, for muh roads.

They took the previous taxes for the roads and spent it on free school, housing, groceries, medical for illegal aliens. Anti-tax prop 13 mindset? The only thing that allows most old folks to keep their houses from tax liens is prop 13. This state though is full of losers who migrated here to the land of fruits and nuts. Add in the new motor voters and you have an electorate that votes for every bond and tax increase every time. The only good that could come from the dam bursting is if it happened to Sacramento.

TBT or not TBT's picture

And then there's moonbeam's fantasy train to blow billions on.