Thread Status:
Not open for further replies.
  1. Mick West

    Mick West Administrator Staff Member

    Moderator Note - deirdre
    A page of quick access links from within this thread can be found at:


    Source: https://commons.wikimedia.org/wiki/File:Oroville_dam_infographic_feb_14.png

    UPDATE 2/14/17 - Evacuation order lifted.

    UPDATE 4:50PM 2/12/17
    Officials Warn of possible collapse of the emergency spillway. Evacuations ordered


    (The above explains why the dam will not collapse. The emergency spillway might collapse, but is separated from the dam itself)

    Source: http://pixel-ca-dwr.photoshelter.co...yfg/G00003YCcmDTx48Y/Oroville-Spillway-Damage

    On Feb 8th 2017, the spillway of the Oroville dam in Northern California failed after a 150ft wide hole formed and significant amount of the underlying hillside were washed away. The large hole forced operators to shut off the flow at a time when the level of water is rising at unprecedented rates. Currently (Feb 9th) the inflow is 130,000 cubic feet per second, and at the time of the failure the spillway was releasing 50,000 cubic feet per second.

    A significant function of dams in California is flood control. If the dam were not there, then the full 130,000 cubic feet per second would be heading down the Feather river through Oroville, Yuba City, and Sacramento. Many areas along the way are behind levees.

    If, as seems quite likely, they cannot quickly repair the spillway then they are faced with a difficult choice. They can either continue to let more water flow down it in a controlled manner, which will cause far more damage to the spillway, or they can let the level of water rise until it goes over the emergency spillway (just visible on the left of the above image).

    Neither option is good. More damage to the spillway will mean very expensive and time consuming repairs, but using the emergency spillway will be uncontrolled, with the possibility of levees being breached downstream. There will also be very significant local erosion, with the greatest risk being that this leads to the failure of the emergency spillway itself.

    The spillway is essentially a lower dam, to the Northwest of the main spillway. It is designed to be overtopped before the dam is. [​IMG]

    The worst case would be if the emergency spillway (which was built in the 1960s and has never been used) starts to erode - potentially leading to the formation of a deeper channel allowing for a rapid uncontrolled outflow from the dam.

    Oroville Dam Spillway2.

    The dam itself would not fail, however a failure of the emergency spillway would lead to some flooding, and significant rebuilding costs. Even the use of the emergency spillway intact would likely mean some downstream flooding if there's a sustained storm. This is referred to in the FERC filings as "loss of crest control"

    Update 2/9/2017: Significant changes overnight with a limited test release. The damage is going in the wrong direction.

    Update Feb 11 2017:
    At around 8:00 AM on Feb 11, the water started to flow over the emergency spillway:

    Related Threads:
    Last edited by a moderator: Feb 19, 2017
    • Informative Informative x 4
  2. Mick West

    Mick West Administrator Staff Member

    The current status is that they are going to re-open the spillway at 20,000 cfs. Run it four hours, and then see how much bigger the hole is.

    They also have a hydroelectric plant that's outletting 13,000 cfs, plus 4,000 from a "fish bypass valve" at the bottom of the dam.

    Current inflow is 83,000 cfs.

    They anticipate eroding away the entire bottom half of the spillway over the season.

    There's going to be increasing media coverage of this. Inevitable there will be fears stoke about the dam collapsing, which isn't really a possibility.

    Real-time data here:
    Last edited: Feb 9, 2017
  3. SR1419

    SR1419 Senior Member

    Here is some video of them doing that. Pretty intense. You can clearly see the erosion taking place. The dam is nearing capacity and with another strong storm tomorrow and more storms expected already in the 10day forecast and only half way through the rainy season this could get interesting.

    • Informative Informative x 2
  4. Mick West

    Mick West Administrator Staff Member

    Looking at the mid-Jan storms shows how rapidly the level will rise.


    The outlook in the catchment area (I'm using Nelson's Crossing as a representative point) is a couple of inches of rain today, then 4-5 days off before the next storm system. Rainfall is likely to be higher in some regions/altitudes, and possible there will be some snowmelt involved. Basically the inflow is remaining very high for the foreseeable future.
  5. SR1419

    SR1419 Senior Member

    Here is a picture that gives some perspective on the actual size of the hole


    It has gotten bigger overnight from their test

  6. Mick West

    Mick West Administrator Staff Member

    Some perspective on cost - a similar sized (but much less steep) spillway on the smaller Folsom Lake cost $900M and took ten years. I'd imagine though that the larger fraction of that was in the upper end with the connection to the dam and the gates. Still, we are probably looking at the hundred million dollar range here as a minimum.

  7. Mick West

    Mick West Administrator Staff Member

  8. Trailblazer

    Trailblazer Moderator Staff Member

    I know you said there is basically no chance of the dam being breached, but if the erosion is proceeding up the spillway at that rate, could it not get dangerously close to the side of the dam itself?
  9. Mick West

    Mick West Administrator Staff Member

    I think the natural geology and terrain was chosen to prevent that happening. Worst case (assuming no major design flaws or undiscovered geology problems) is erosion up towards the power lines, then they would likely use the emergency spillway
  10. Mick West

    Mick West Administrator Staff Member

  11. Mick West

    Mick West Administrator Staff Member

  12. SR1419

    SR1419 Senior Member

    here is video- looks really messy.

  13. Mick West

    Mick West Administrator Staff Member

    Some people are comparing this to the 1976 Teton Dam failure. It's nothing like that. The Teton dam failed because of bad design, and geological factors that were not correctly dealt with. The Teton failure was in the dam itself, and did not start in the spillway. The Oroville spillway (and the emergency spillway) are sufficiently far from the actual dam to avoid any damage to the dam, no matter how uncontrolled the spillway releases become.

    The following images are of the Teton dam failure, again the spillway failure is nothing at all like this, and will not lead to this.
    Last edited: Feb 9, 2017
  14. Mick West

    Mick West Administrator Staff Member

    So the current plan from CA-DWR is to run 35,000 cfs down the spillway, and hope the head-cutting (uphill erosion) does not keep going. They are now running it continuously.

    Engineers are fairly confident that the head-cutting will reach bedrock at some point, and they will be able to continue to use the main spillway, destroying only the lower 50% or so.
  15. Mick West

    Mick West Administrator Staff Member

    Yeah, and they basically have to keep that going 24/7 to avoid using the emergency spillway. They are letting out less than half what is coming in, so they will want to try to lower the level over the dry days to make room for the next storm.

    Source: https://twitter.com/MavensNotebook/status/829796535810535426
  16. Mick West

    Mick West Administrator Staff Member

    Conspriacy theories starting:
    We'll see more nonsense speculation like this when the story gets picked up by the national press. Mostly the current bunk is of the form "the dam is going to fail".
  17. Mick West

    Mick West Administrator Staff Member

    A worst case scenario being suggested is the emergency spillway itself eroding. and this erosion making it's way over to the dam, which would then fail.

    However it looks to me as if there is bedrock between the spillways and the dam. Indeed the head of the main spillway seems to be set deep within the rock.
    The above, and this photo from 1968 appears to show the main spillway is cut through rock.
    Last edited: Feb 9, 2017
  18. Mick West

    Mick West Administrator Staff Member

    Something I've seen a few times is the suggestion that there's no rebar in the concrete, and this is an indication of shoddy construction, corruption, etc. However it seems to be from looking at images of the 200 foot wide spillway from a distance, where 1" rebar would be invisible. Like this:

    If we zoom in though, you can see the shape of the rebar lattice in the concrete and some lengths of rebar.


    And a close-up of that area reveals the actual rebar swept downstream.
    Last edited: Feb 9, 2017
    • Informative Informative x 1
  19. Mick West

    Mick West Administrator Staff Member

    Friday morning, starting to get light. Outflow has been bumped to 65K cfs for the last four hours, massive damage to the lower spillway will be likely.

    Inflows are declining, to 145K cfs and falling

    They are not falling rapidly enough though, water levels are seven feet from the emergency spillway
    (Data source: http://cdec.water.ca.gov/cgi-progs/queryF?s=ORO )

    Just some light rain expected for the rest of the day, but there was some solid rain overnight.

    Looks like DWR are trying to hold off the emergency spillway as long as possible, as the increase to 65K was a risky move.

    I expect this to be big news today, as we are going to have some spectacular photos coming in. There's already a story in the Daily Mail.

    Inevitably this will lead to apocalyptic stories about dam failure (the integrity of the dam is unrelated to the spillway, as it's round the corner, behind a lot of rock). Expect conspiracy theories, and political exploitation regarding infrastructure investment and departmental authority.
    Last edited: Feb 10, 2017
  20. Mick West

    Mick West Administrator Staff Member

    If you do some extrapolation on the graphs it actually seems like there's a chance they might avoid the emergency spillway usage if they keep at 65K out. Depends if the inflows continue to decrease (which will also slow the level rise). Inflows set to match outflows at 23:00 (11 PM).

    These are all just very rough extrapolations though.

  21. Mick West

    Mick West Administrator Staff Member

    Excellent set of photos this morning:

    Source: https://twitter.com/CecileJuliette/status/830093907790749696

    The bottom half of the spillway is still there, but probably not for long as the surrounding hillside is stripped down to bedrock.

    Clearing trees where they can get to them. You can see where the water will flow down the ravine to the left of the road. There's lots of trees in there they can't easily reach.
  22. Mick West

    Mick West Administrator Staff Member

    Slideshow of the area this morning, with some footage of downstream minor flooding.

    Source: https://www.youtube.com/watch?v=1dBPk2cpcyk

    This view is from above the dam, looking over the emergency spillway. You can see the water is near the top. Also see the trees cleared.
    • Like Like x 2
  23. Spectrar Ghost

    Spectrar Ghost Senior Member


    How far from you is this, Mick?
  24. Mick West

    Mick West Administrator Staff Member

    About 70 miles.
  25. Blinkenlights

    Blinkenlights New Member

    Thanks for the updates. If I'm reading the topography right on Google Earth, there's at least one electricity pylon in danger if the emergency spillway overtops...
  26. Steve Funk

    Steve Funk Active Member

    Meanwhile, Shasta Lake as of noon was 8.66 feet from the top. Releases are 38,000 CFS, only 55% of maximum, with 104,000 CFS coming in, but they will probably have to increase releases to the maximum by tomorrow morning. I could foresee a flooding problem in Sacramento if this is combined with extraordinary flows from Oroville in the next few days. However, agencies don't seem to be overly concerned.
  27. Mick West

    Mick West Administrator Staff Member

    The Oroville flows are not that extraordinary, they would probably be letting out more if they did not have this problem.

    Locally Folsom releases are 80,000 CFS for inflow 127,000. Level is 447 feet out of 466, rising about 0.4 feet per hour (about 10 ft per day) probably not an issue with five days of sun ahead. Lots of roads out though as everything is saturated and there's landslides.

    Sacramento IS flooding in the riverside parks and suchlike. Next storm might be a problem. Too soon to tell.
  28. Graham2001

    Graham2001 Active Member

    The conspiracy theorists, trolls and whatnot are coming out into the YouTube comments of the various news videos covering this incident. I am linking directly to the videos in question below. I will add that I think the AP headline is irresponsible, as it does not make it clear that the hole is in the spillway.

    Fears Over Oroville Dam Spillway Grow As Hole Gets Larger

    Source: https://www.youtube.com/watch?v=Y4erbPyYbmc

    As a side note, similar claims surfaced in Australia following the Queensland floods in 2010/11.

    200-Foot-Long Hole in Damaged Calif. Dam (Associated Press)

    Source: https://www.youtube.com/watch?v=T595rAtZH20

  29. Mick West

    Mick West Administrator Staff Member

    Armchair engineering. If they attempt a 30 hour fix (very unlikely timeframe if you look at the size of the hole, the terrain and access road) then you've also got to gamble that it holds, while you've also got a lake that's now very close to overflowing, so you'd have to push 100K cfs down something you just slapped to together with no testing or meaningful inspections.

    With hindsight they could probably have had better inspections, as always.
  30. MaryL

    MaryL Closed Account

    To: Mick West

    Tonight, on KRCR news (Redding, CA), Jerry Olinen, reported that in 2013 the Oroville Dam spillway had a problem (break in the concrete) in the same exact area where the hole started on Tuesday. Jerry posted pictures of several white DWR trucks that were parked on the spillway in 2013 during inspection and repairs. Jerry asked DWR 'Chief' engineer today, why this problem area wasn't inspected more thoroughly (was it preventable?)...Only visual inspections were done in 2015. The Chief engineer responded that "we didn't think we had a problem...". Really?

    This is awful, and no one but the Feds should be liable for paying for the fix. Right? Help me understand?

    [link added:
    • Informative Informative x 1
  31. deirdre

    deirdre Moderator Staff Member

    why should the Feds be liable?

    • Agree Agree x 1
  32. Steve Funk

    Steve Funk Active Member

    Looking at the photo at the top of #18, it looks possible that the softer brown material eroded away from underneath the spillway, becoming semiliquified as the soil saturated with water. This would create a void where the spillway was not supported from underneath, leading to the failure.
    • Like Like x 1
    • Informative Informative x 1
  33. Mick West

    Mick West Administrator Staff Member

  34. Mick West

    Mick West Administrator Staff Member

    Now at 899.16 of 901 feet, still rising around .25 feet or so per hour. The had to reduce the flow, and it has been raining a bit. Going to be really close. If it's going to overtop then it will probably be sometime Saturday morning.
  35. qed

    qed Senior Member

    Has anyone tested for nanotermites?
    • Funny Funny x 7
    • Like Like x 1
  36. Pete Tar

    Pete Tar Moderator Staff Member

    Wrong for what? Doesn't the damage creeping closer to the source increase the failure likelihood?
  37. Graham2001

    Graham2001 Active Member

    • Informative Informative x 1
  38. Mick West

    Mick West Administrator Staff Member

    Last edited: Feb 11, 2017
    • Informative Informative x 1
  39. Graham2001

    Graham2001 Active Member

    • Like Like x 1
  40. Mick West

    Mick West Administrator Staff Member

    This is from yesterday.

    Notice the freshly concreted rocks at the bottom. A quick fix, and shows the very real concern of damage to the emegency spillway. If that gets undercut there's a BIG problem
    Last edited: Feb 11, 2017
Thread Status:
Not open for further replies.