DWR Briefing on the Oroville Dam

This is an interesting briefing video from about noon today. Tech Talk about the problems and what they are doing.

Interesting to note that the powerhouse is closed down so that water backing up (from the debris from the spillway) won’t be a problem…

Update: This is a KCRA video of the same original update on 11 Feb:

And I’ve added the Evacuation Briefing:

I also find it interesting they say that the power plant can’t run disconnected from the grid, and the power lines go out over the spillway with a tower at risk. Right now, the power plant is shut down and water can’t be run through it. The main spillway is being limited to about 55,000 CFS to prevent too rapid decay. That leaves only the Emergency Spillway to take anything over the limited run down the regular spillway…

Then the spillways are building a pile of sediments in the pool at the bottom and that threatens to back up water into the powerhouse. So they are looking at how to dredge while all this is going on.

I’m glad it isn’t my problem to solve…

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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120 Responses to DWR Briefing on the Oroville Dam

  1. Larry Ledwick says:

    Yes! Not a problem I would want to deal with either. Emergency response is often a case where you have a sudden onset problem you did not fully anticipate, and the situation rapidly degrades with only a finite time window to come up with a solution. Logistics problems make it even worse that although you can come up with a plan getting all the “stuff” there on time and in place is like a war time scenario, you only get one chance to get the job done in many cases and the time clock is always ticking.

    Often by the time you recognize the problem it is too late to fix it, and you can only manage the failure as best you can.

  2. andysaurus says:

    They have a similar problem in electricity generation here in Aus. In lefty loony South Australia they rely on 40% wind energy and they took great pleasure in blowing up their coal fired generator last year. Of course the windmills need a synchronous input to keep working and if it fails they stop. To assist their supply they leech power from an interconnector with Victoria next door. Last year they had a storm that blew so hard the windmills couldn’t cope and shut down. All at once. The interconnector’s safety cut in and it shut down too. Any remaining wind then had no synchronising signal so it shut down too. That was it – statewide power outage. Oh how I laughed. (I live in Queensland).
    Today, when it was 39 degrees C, we had a high voltage power outage that stopped my supply. With some foresight I have installed government subsidised solar, but of course that also needs synch. With even more foresight I have a generator capable of running all my fridges, freezers and airconditioners. I had just set it up and run all the extension leads when, guess what.
    As far as Oroville dam is concerned, it looks like you have much better engineers and politicians than we have here. In 2011, when we had a socialist state government, they ran their main Brisbane dam up to 120% because, of course, “the rain that does fall will not fill the dams”. That dam was designed to go up to 200% with the extra for flood mitigation. When a major storm cell threatened everybody panicked and released the floodgates, just in time to meet a major flow from upstream. Result – probably broadcast internationally. Brisbane is built on a flood plain.
    By the way, they also built a totally unnecessary desalination plant and a grid to link all the dams at huge cost. All out of our pockets, but it gave the unions a chance to gouge the costs, so all was not lost. /sarc
    If they can’t find a solution to this one, I suggest they look up Barnes Wallis.

  3. LG says:

    Some links for California’s Department of Water Resources.
    Hydrology. Precipitation. Snow pack Water Content. Ground Water Information.
    As of 07:41 on 2017 02 12 Shasta, Oroville ,Don Pedro reservoir are @ 96% capacity or higher.

    Millerton,San Luis, Castaic and McClure are at 85% or higher.


    Click to access PLOT_SWC.pdf


  4. pg sharrow says:

    This is beginning to look like a cascade failure. They really need something to go right as disaster is looming. I have seen the bathtub rings in the Feather River tributary canyons where I once looked for gold. This is scary. Glad I live 2,000 feet above the Valley floor…pg

  5. E.M.Smith says:

    Glad I don’t live 12 miles ‘down river’ from Oroville anymore… nor own any property there…

    As of now, the only question is “Warm heavy rains and overtopping?” or “Cold snowpack and slow melt while emergency repairs let them continue to drain ‘enough’ from the broken spillway?”…

  6. pg sharrow says:

    This slow moving wreak is in progress. The dams are brim full, no flood control space left. The rivers and streams are bank full. The irrigation canals and storage areas are full, the Rice fields are full. The mountains are nearing 200% snowpack and it is warm and wet. About Thursday night another week long series of warm and wet storms are due. The drain for the Great Valley is through a narrow canyon to San Francisco Bay……………… things COULD get ugly.

    Remember California climate runs from desert to swamp, drought to flood, sometimes in the same year. Which is why the Real Californians tried to put large reservoirs in all the canyons. Too bad the Ecoloons stopped that project 30 years ago. Now they will learn again that the Great Valley Paradise was Man Made, and not a gift from GOD…pg

  7. LG says:

    Apparently, Existing structural Damage in the same location where the spillway broke was known to the DWR back in 2013

  8. Larry Ledwick says:

    I hope FEMA is getting their act together in case this gets away from them. It could be a Katrina class + disaster if they lose it.

    Keeping fingers crossed for the folks in that area, that they squeak by and get through this without a major failure.

  9. M Simon says:

    If I was to hazard a guess on the spillway problem, based on earlier repairs I’d say bad concrete. Not enough cement (a standard contractor cheat)?, Not enough rebar? Something else?

    Someone probably knows – from testes done on the repaired section.

  10. Larry Ledwick says:

    Could also be bad design, note that the water over the spillway has a free run all the way to the bottom of the slope before it runs into any anti-cavitation and energy dissipation structures like chute blocks or hydraulic jump structures. Aerated flow is much less likely to create cavitation damage to the chute lining..

    Click to access VI-3-20150610.pdf

  11. Pingback: Classical Values » Oroville Dam May Flood Sacramento

  12. Larry Ledwick says:

    Oh Oh
    From Twitter
    Fox News ‏@FoxNews 5 minutes ago

    BREAKING: Officials order evacuation of areas near damaged Oroville Dam in California

  13. M Simon says:


    YouTube has pulled the video you used.

  14. Larry Ledwick says:

    Evac orders are always a devils choice, bumping outflow to 100k cu ft/sec could be a problem if they have flow so high it blocks exit routes or takes out smaller down stream bridges / structures before people can get out of harms way.

    This big of a deal is a career ender if they are wrong and a career ender if they are right.

  15. M Simon says:


    The next two weeks are probably the most critical. They don’t expect to be out of the woods for 90 days.

    My best guess? A dam collapse floods Sacramento by the 20th.

    Good concrete takes about 7 days to reach useful strength. California has a very large logistical problem on its hands even if things do hold for another week.

    Will they ask the President for help? Ha.

    They have painted themselves into a corner.

  16. M Simon says:

    From DNR CA.

    EMERGENCY EVACUATION: Auxiliary spillway at Oroville Dam predicted to fail within the next hour. Oroville residents evacuate northward.

  17. M Simon says:

    Well that was fast. From my prediction of a collapse in a week until the announcement of collapse within the hour (but only the spillway – so far) in about 10 minutes.

  18. Larry Ledwick says:

    That was originally put out over an hour ago see my link at 1:22 and 1:26 above. It is already at the time they forecast possible failure to begin.

  19. Larry Ledwick says:

    The major media have known about this for at least 1 hour 15 minutes and still nothing on the national TV networks – can’t cut away from the awards or even run a screen crawler??

  20. Larry Ledwick says:

    Streaming from the local area



  21. M Simon says:

    “The major media have known about this for at least 1 hour 15 minutes and still nothing on the national TV networks – can’t cut away from the awards or even run a screen crawler??”

    It would reflect badly on Democrats. And you know that was forbidden.

    BTW I had not read your links when I made my prediction.

  22. Larry Ledwick says:

    Evacuation warning area map

  23. Larry Ledwick says:

    So far have not found a streaming feed that was intelligible, all keep breaking up the audio or just hang.

  24. Terry Jay says:

    By now it is too dark to see and too big to light.
    Hope is not a strategy, but here’s hoping……..

  25. Larry Ledwick says:

    This link has helicopter video, showing cars backed up bumper to bumper trying to get out.


  26. Jeff says:

    This thread has been following the situation for a couple of days now, and has people (almost) on-site. There are many, many, videos and pics. There is also some snark going on, but lots of stuff isn’t hitting the news at all. There’s a fellow with mobile video out filiming it (drones not allowed, and it looks like KCRA hasn’t been filiming much since yesterday.


    (they’re upt to 104 as I type this)
    Prayers for everyone out that way…. looks like a case ot too little too late….

  27. Larry Ledwick says:

    Yes I am surprised that there is essentially a total media blackout. Even the online presence of the major media only have a small item posted with no real sense of urgency.

    Having worked in emergency management I realize that they may have asked the media not to make too big a deal over it to keep from creating a panic evacuation which would totally grid lock the roads out of town. If the locals think they have some time and try to move out calmly in the long run you would get more people out of the area.

    Or the sheriff has put a lid on the media. I have not seen any FAA flight restrictions posted so far.

  28. Larry Ledwick says:

    This local live stream is working.

    It appears the Sheriff wanted to get ahead of the situation and made the call early!
    (Bravo good decision)!
    So at this moment the coverage is calm and routine but the evacuation continues.

  29. Larry Ledwick says:

    They are now filling rock bags for helicopters to drop tomorrow when they get daylight.

    Right now evacuation totals are about 130,000 have been asked to leave the high risk zone.

  30. pg sharrow says:

    the local channel 12 is live with events,.the damaged overflow is dumping 100,000cfs to lower the lake level at the failing emergency spillway, last check was about 2 inches over the rim. inflow to the lake was 43,000cfs mandatory evacuation of Oroville and lower towns in Butte county as well as in Marysvllle and Yuba City. And of course looters and vandals are striking in Oroville as the people move out!…pg

  31. David A Anderson says:

    I hope this is a good photo showing the erosion to the emergency spillway.

    E.M. is certainly correct about not wanting to make such decisions. ( Turns out the ? two plus day turn off of the damaged spillway may have been the wrong decision, allowing the emergency one to come into play.
    I saw the picture of the concrete burm and immediately noticed how short it was before going to dirt. Yet I assumed the geology must be very well mapped and mostly solid rock. Clearly running heavy CFS to soil would create massive erosion just past the dam. It appears sadly obvious at this point that the concrete should have extended much further.

  32. Power Grab says:

    A commenter on Breitbart said that the dirt slope was what was holding the dam in place. If it gets washed away, the dam is more likely to fail.

    Twitter had lots of informative stuff. Turned on the TV and found nothing.

  33. David A Anderson says:

    PG, at that rate they should have been within an hour at most of getting below the emergency rim

  34. David A Anderson says:

    PowerGrab, true yet vague. Look at the photo in my link just above. See the steep v erosion in the emergency skills at. It was much gentler before it eroded away. IMV if the V oes, the lake goes, rapidly eroding and taking out the regular spillway,. BOG WAG, 20 million plus CFS into the Feather.

  35. Larry Ledwick says:

    Emergency spillways are often intended to only have an inch or two of water depth going over them, and if planted in deep rooted grasses etc, that sort of slow sheet flow will not cause erosion. They also often cover the slope with large rocks which prevent erosion and slow the flow, if the water is not moving too fast.

    Deep rooted plants like trees and bushes should never be allowed to grow on the face of a dam. An earth filled dam is often built like a layer cake with layers of compacted clay in the slope to act as a water seal to prevent “piping” where seepage slowly bores a pipe through the dam. Tree and brush roots can help that process happen by penetrating those compacted clay layers, and once the over flow starts unlike grasses and reeds that lay down and protect the slope, brushes and trees create eddies which quickly scour away the soil starting a massive erosion process.

    If they did not care for that slope (ie they had to cut trees etc which implies it was not properly managed) then once the flow starts cutting into the soil there is nothing to stop it.

  36. DonM says:

    I would have been nervous had I been on the podium giving an update as the Acting Director of DWR, but I definitely would not have forget the difference between cfs and acre-feet.

    This yutz says that they are running at 65,000 acre feet per second. I do feel bad for him. Where did the director go? When will a new acting director be hired?

    Find competent engineers and put them in charge, and let them be responsible. Get rid of non engineer administrators and administrators that happen to have engineering licenses from cubical work that they did 30 years ago.

    This is just sad.

  37. E.M.Smith says:

    Well… I take a couple of hours to visit some friends and watch an episode of Sherlock and what happens? The whole thing goes to hell…

    The “emergency” spillway is eroding like an icecream bar in the sun, they opened the damaged spillway back up to the level that was eroding it away earlier, and we’ve got evacuations ordered as night falls.

    This with 10,000 level of CFS of flow over the “emergency” spillway that is supposed to take 200,000+?

    If the rest of that hill is as crumbly as the first few meters have been, it washes out at that full flow level and we start cutting a new river right there.

    That hill is the abutment for the dam. If that hill destabilizes, the dam is just a pile of clay and fill for about 700 of the 900 feet. It washes away in a river scale flow.

    This has gone from bad to OMG in just 1/2 day? OMG…

    I’d really like to know what that hill is made of and what the USGS survey of it showed.

  38. Larry Ledwick says:

    Video of an actual dam failure (by design) through a soft plug in the dam flank for graceful failure.

    graceful failure of Auburn cofferdam

  39. E.M.Smith says:

    Oh, and that valley has very steep walls. There wasn’t really much choice about how to get the water from 900 foot up down to the riverbed. I suppose they could have tried to make a concrete traverse run, but the slope is so much all the water would be on one edge of it… I think they basically only have a choice of “straight down the hill” since they could not build a 100 foot wide chute traversing the hill without having 80 foot of it high and dry on the upside…

    The real question is just “what is that hill made of?”. IFF solid rock and NOT giant boulders, then we’re just washing a facing off of it and who cares. BUT… if that hill is really just large chunks of rocks stacked with fill between them and nobody noticed it’s broken up, then all that water can cause a washout on the shoulder of the dam.

    That they are having continued scour problems on both spillways does not argue for “bedrock just a couple of feet down”…

    I’ll see if I can find a video to replace the one taken down.

    I think the area of their flash flood warning is ONLY for a “minor” erosion of a few feet of emergency spillway, and not for loss of the dam. That implies they think there is non-erosive bedrock maybe a dozen feet down, but don’t want to find out the hard way.


    Yeah, the guy is clearly feeling a bit rattled mixing AF and CFS. I think he is at his limit on what to do. Not screwing up, but not comfortable either.


    The area with the spillways is not part of the dam. It is a natural mountain. Swift drop of about 900 feet on both sides (one into the lake, the other into the river). In the area there are lots of “table top” mountains made of volcanic flow. There are also uplifted sediments (we collected sharks teeth further up slope…). The question is “what is this hill made of?”…

    That it eroded to 900 feet down on each side with very steep slopes implies it isn’t erosion proof, but IIRC, the major rocks found under the soil there ARE volcanic solid heavy things (igneous non porous); so I’ve got some cognitive dissonance… The soil is very iron rich red, so weathered from igneous… just how rotted is the deeper rock, though?…


    FWIW I just watched an update on Fox (who cut away from the Q&A part of the Sheriff and DWR guy) and SF Channel 2. So once the situation was dire and the evacuations ordered they covered it… IMHO that puts them in the Blood and Guts Disaster Entertainment business not in the public information service…

    So where are they now?

    They have 3 means of draining water. In this season, about 100,000 CFS is normal and they can run up to about 130,000 to 150,000 (and have, with only minor flooding) and that is likely to be needed in the next weeks up to a couple of months with a 180% of normal snowpack to melt and more storms on the way. Of their three choices:

    1) Powerplant at about 12,000 CFS: Can not be used as there is no sync current and the outflow is being plugged by debris from the spillways. Powerhouse threatened with flooding from the backup. Powerlines taken down, so days to weeks to get powerlines (and sync) back and channel dredged during which time outflows from the spillways must be low. I.e. not in the next few weeks.

    2) Regular Spillway: When run at 100,000+ it was eroding horridly, so they cut it back to 55,000 to save it for long enough to emergency patch the eroding uphill face a bit later in the season. Now running at 100,000 but for how long? Umm… where did we leave those dice…

    3) Emergency Spillway: At 10,000 to 12,000 flow for 1/2 day they saw large unexpected erosion and thought they might lose the concrete topper (so would let about 20 to 30 foot of flow out… and cut a new river…). Evacuated down stream and cranked up the other spillway to damage levels.

    Looks to me like: Blocked, breaking, and washing out.

    IFF they are very lucky, and get a break in the weather for a week, they can place large rock and very fast concrete in a hope of stabilizing erosion. There are some cements that set up in 8 hours and are hard enough in 24, but getting them mixed and onsite before they set up will be a problem… Everything has to come in up a winding narrow road with mountain on one side and valley / river on the other, and no place to turn around in the middle… and a runaway spillway causing erosion of the bank below the road… Can you move 500,000 CF of concrete by helicopter in 8 hours?…

    These folks have their winky in a wringer and I think they have started to notice that nature is turning the crank and not listening to them…

    Right about now someone, somewhere, is saying “But they told me we were having a drought!?…” and it will start to dawn on some folks that we have not had a drought for 2 years now…

  40. andysaurus says:

    I would just like to point out that the last video I saw had water escaping from the mountain to the left of the spillway (as you look at the dam), and from below the level of the spillway. That means it is already tunnelling through the soil. It doesn’t take long to go from that to disaster, hence the boy with his finger in the dyke.

  41. M Simon says:

    It has been a ling time since I studied concrete ( so I may not be entirely correct) but fast setting cement doesn’t get to near its full potential strength until 7 days and is not considered fully cured until 30 days.

    And don’t forget “full strength” is compressive. strength. For tensile strength you need rebar.

    Assuming the dam holds – they have until October to make all repairs. About 4 or 5 months after the end of the rainy season. The logistics are going to be a biatch. And then there is agricultural production.

  42. M Simon says:

    Also – fast setting has lower ultimate strength.

  43. philjourdan says:

    I have been following it for a few days. What I do not understand is why they thought they could get away without using the Emergency Spillway when the intake was about 130k cfs, and the regular spillway was only doing 65k cfs. THe math just does not add up.

  44. Clay Marley says:

    Now that the immediate threat appears to be over, with the water level below the weir, what do they do with the 188,000 evacuees?

    Today we should see some interesting videos as they helicopter in bags of boulders. Meanwhile they hope to reduce the lake level to 850 feet before the next storm system Thursday. So the next major risk is in how well the main spillway holds at 100K.

    Assuming they can maintain 100K, the risk next depends on the storm system. They said it is expected to be a cold system, meaning much of the water above the dam will fall as snow. But the weather forecast I saw said it would start as a warm front with rain well above the snow line, then eventually the snow line would drop. This could result in both rain water and melting snow initially.

    Its all up to Mother Nature now. If water flows over the emergency spillway again I expect any flow could result in another round of evacuations. Those folks are going to be tired and frustrated.

  45. David A Anderson says:


    See forecast for western Sierra here. In my experience with the very low pressure of the latter 10 day period those rain and snow amounts will increase, maybe a lot.

  46. David A Anderson says:


    Level lowered to 899.75 as of yesterday.

    Inflow outflow not listed???

  47. David A Anderson says:

    01/15/2017 851.34 2826365 -4044 2788000 38365 19765 17670 13 17380 0.00 24.40 0.00
    01/16/2017 850.75 2818423 -7942 2788000 30423 19768 15874 42 15159 0.00 24.40 0.00
    01/17/2017 849.86 2806473 -11950 2788000 18473 19785 13713 21 13688 0.00 24.40 0.00
    01/18/2017 849.66 2803792 -2680 2788000 15792 17730 16459 13 18739 1.08 25.48 0.08
    01/19/2017 850.56 2815869 12076 2788000 27869 14333 20379 25 21057 0.28 25.76 1.20
    01/20/2017 851.67 2830813 14944 2788000 42813 12716 20351 33 21655 0.92 26.68 0.40
    01/21/2017 852.76 2845543 14730 2788000 57543 11081 18452 13 18455 0.32 27.00 0.60
    01/22/2017 854.15 2864404 18861 2788000 76404 11053 20571 9 21432 0.44 27.44 0.40
    01/23/2017 855.05 2876663 12259 2788000 88663 11031 17241 30 17122 0.00 27.44 0.36
    01/24/2017 855.45 2882123 5460 2788000 94123 11099 13950 30 13561 0.08 27.52 0.08
    01/25/2017 855.36 2880894 -1229 2788000 92894 11151 10552 21 10063 0.00 27.52 0.00
    01/26/2017 855.36 2880894 0 2788000 92894 11331 11430 30 10986 0.00 27.52 0.00
    01/27/2017 855.17 2878300 -2594 2788000 90300 11117 9627 25 8959 0.00 27.52 0.00
    01/28/2017 854.84 2873800 -4500 2788000 85800 11366 9191 25 8169 0.00 27.52 0.00
    01/29/2017 854.39 2867670 -6130 2788000 79670 11417 8420 25 7632 0.00 27.52 0.00
    01/30/2017 853.76 2859103 -8567 2788000 71103 13079 8862 34 7744 0.00 27.52 0.00
    01/31/2017 852.48 2841754 -17349 2788000 53754 17077 8300 38 8160 0.00 27.52 0.00
    02/01/2017 850.78 2818827 -22927 2788000 30827 20187 8644 17 8244 0.00 27.52 0.00
    02/02/2017 849.14 2796832 -21995 2788000 8832 20463 9381 8 9088 0.48 28.00 0.04
    02/03/2017 — — — 2788000 — 25772 20210 27 23941 — 28.00 0.64
    02/04/2017 849.20 2797635 — 2788000 9635 30014 36027 19 39077 0.12 28.12 0.36
    02/05/2017 849.35 2799641 2006 2788000 11641 29911 30856 0 34590 0.88 29.00 0.12
    02/06/2017 850.85 2819768 20127 2788000 31768 38741 48795 42 55286 1.48 30.48 1.00
    02/07/2017 862.31 2976908 157140 2788000 188908 27425 106845 62 115181 0.40 30.88 1.68
    02/08/2017 874.84 3155684 178777 2788000 367684 11687 101841 24 116554 r 1.12 32.00 0.20
    02/09/2017 890.92 3396134 240449 2788000 608134 34253 155498 13 175615 2.04 34.04 1.04
    02/10/2017 899.44 3528727 132593 2788000 740727 60697 127679 53 137355 0.16 34.20 2.00
    02/11/2017 902.57 3578367 49640 2788000 790367 59472 84437 23 89622 0.00 34.20 0.16
    02/12/2017 899.77 3533936 -44431 2788000 745936 -5041 -5041 -5041 — 0.00 — 0.00
    02/13/2017 — —

  48. David A Anderson says:

    Phil, it would not have overflowed if they could have used the regular spillway. They shut it down for too long.

    Click the link just above. Click on ORO. Then click on any daily to get the past 30 days.

  49. E.M.Smith says:


    They don’t need high strength concrete, just strong enough to prevent rock from moving. You can get that in 24 hours. There is also now exotic cement that was used for runways in war zones that sets in 4 hours and is usable in 12 to 24 depending on impact load.

    @Clay Marley:

    Yup. All up to the weather… and they talk about “control” of the dam, the spillway, and the situation…


    The emergency spillway was asserted to be rated at about 250,000 cfs. The stated strategy (in the now missing video) was to let it take anything over 55,000 to protect the main spillway from erosion (that had been observed at over 100,000 cfs…).

    What they found out was that at 10,000 the E.Spillway was eroding fast… so today they will be inspecting the (now exposed) surface and deciding what it can really take.

    They need to find a strategy that lets them dump 100,000 for days on end, and about 50,000 ongoing, given two spillways both showing erosion, but without much more erosion, over the next 4 months of rain, snow, and snowmelt

    I fervently hope they discover solid bedrock and figure out the original engineering was good, but expected to scour a few feet of soils off the bedrock, and they were panicking without cause. I fear they will find the original assumption was bedrock and they have found consolidated boulders becoming unconsolidated…


    I think you are seeing an artifact of video resolution.

    The area to the right of the regular spillway IS the emergency spillway, even past the concrete wall and including the inundated parking lot. ALL the water to the left of the spillway is taking the designed E.spillway path.

    Then, what looks like water coming through the hill is actually just where the transparent sheet flow becomes turbulent and aerated as it hits rough surface rocks. There is transparent sheet flow over the rounded concrete wall , down the face, and over a concrete skirt to that rocky whitewater, but video resolution is too low to see it in distant shots .

    The problem is the rate and depth of erosion in that soils and rock whitewater area. There had been a road to the parking lot there, on a wall about 30? feet high. It is now gone… IF that erodes toward the regular spillway maybe 200? feet more, it starts to undercut the head of the R.spillway… that’s a huge AwShit… so I hope there is lots of concrete there we just can’t see.

  50. tom0mason says:

    From mosomoso at http://joannenova.com.au/2017/02/california-oroville-dam-may-break-evacuations-underway/#comment-1890136

    Is this interesting comment —

    Maybe this flood was unprecedented: https://www.scientificamerican.com/article/atmospheric-rivers-california-megaflood-lessons-from-forgotten-catastrophe/

    Well, actually it wasn’t. Native Americans at the time already knew that the San Fernando Valley could become a sea. Which it did in 1862, after two decades of crippling drought. Further north, Sacramento and San Joaquin valleys (the Sacramento is below Oroville) were entirely flooded.

    All before we had climate change!

    and also

    February 13, 2017 at 9:31 pm · Reply

    In 1909, the Feather River Basin, which is in the vicinity of Oronville, copped 1,458 mm of rain in 20 days, which, according to some boffins, is only supposed to happen once every twelve millennia in those parts. Mind you, I’d rather have strong dams than comforting statistics.

    In view of events like those of 1861-2 and 1909 it would be surprising if anyone dared to use the magic word “unprecedented” about present conditions in Northern California. Actually…it wouldn’t be so surprising.

  51. tom0mason says:

    The locals are upset at the lack of action before the spillway had problems …

  52. Larry Ledwick says:

    Several things going on here now. The first problem is normalcy bias and procrastination. The big challenge in emergency management of this kind of situation is you absolutely must stay ahead of the curve! Thinking hours days even weeks ahead of current events, because some decisions cannot be taken back or mitigated once you realize they were not the best choice.

    Local governments and Federal agencies tend to wait a bit too long to make decisions and think with too short of a time horizon.

    As far as the evacuees this is going to turn into a major public relations nightmare. First to make clear given the information he appears to have been given the Sheriff made the right call, better early and unnecessary rather that late or not at all on evacuations. But!
    He is going to be dealing with 188,000 pissed off people in the next few days. Store owners are losing business, some folks are losing things to theft and looting, folks are losing wages from not getting to work etc.

    The evacuees will tolerate the discomforts and difficulties as long as they are concerned for their welfare and think a problem is imminent. Once they start to wonder if the evacuation was unnecessary a very vocal minority will get really angry and make a mess of things. The Sheriff might lose his job in the long term, unless they do have a major failure of the dam, then he will be a hero or a goat, either lauded for calling the early evacuation, or demonized for not doing enough to save the dam.

    Regardless the town of Oroville is now a dying town economically, as for the first time residents will be uneasy with the dam and recognize it “could” fail or have problems. Property values will drop, people will move out or be unwilling to move in. Lots of money and effort will be made to come up with better evacuation routes and warning systems etc.

    As far as the dam is concerned if they squeak by with no significant failure they will spend millions on redesigning and enhancing the spillway and doing proper maintenance of the emergency spill way slope and vegetation. That slope needs to be improved. The over flow apron at top needs to be longer and have energy dissipation blocks on it to slow and aerate the flow. The rock and rip rap placed on the slope to distribute and disrupt the flow so it does not build up enough energy to cut the soil. The lower slopes need to be cleared of brush and trees and planted with deep rooted grasses (and be watered and maintained so the grass is thick and will create a durable sod layer that will tolerate sheet flow of water several inches deep).

    The main spillway needs to be re-engineered with modern understanding of cavitation damage in fast flowing sluice channels like that, and of course they need to dredge out the outlet ports of the power channels and reconnect the power lines so they can get it back on line and passing water.

    There will be ongoing work here to fix the dam and re-engineer the immediate down stream flood plain for the next 20 years, but right now they need to take care of the evacuees allowing them to return briefly to take care of pets, pickup changes of cloths etc and get them in a stable situation or the political back wash will be a nightmare for the local government.

    Big problem for the locals, I hope they get lucky and the weather cooperates for the next few weeks or so.

  53. David A Anderson says:

    Weather not looking good
    Read the scientific forecast discussion.

  54. E.M.Smith says:


    In that 1861-2 event, the Sacramento Valley was christened “Lake Sacramento” and folks got around the capitol in boats… After the water lowered, the entire area of Sacramento near the river was filled with landfill and raised 14 feet to just above the level of the flood…


    To give an idea what could be done: Near Oroville there are massive “dredger ponds” and “dredger tailings”. A tiny part of them were mined to make the dam itself. There are still miles of them. I’ve walked and ridden over miles of them. These are largely stone cobbles of about 4 to 6 inch diameter (the dredging nicely inverted the soil structure and put the big rocks on top…) and these are rounded river washed.

    A massive truck brigade could pick up loads of this and dump it on the E.Spillway surface, then dump fast setting cement (mostly sand and pea gravel also available locally) to fill the voids. 24 hours later you have a concrete and rounded cobble surface that will take water flow nicely without significant erosion. If you have 48 hours to cure, even better. A 6 inch cobble / cement cover is enough for most of that facing (it is thicker than what is used in local ditches and weir facings…) and is clearly better than the loose dirt they have now. If it washes away after a few days, you have gained a few days, and repeat with a 12 inch layer. If it doesn’t wash away, next dry time you put another 6 inches on top…

    Biggest problem is getting enough cement mixed and in place fast enough. The rock transport is just getting trucks and loaders to head that way from anywhere inside a week drive time. Roads into the dredger tailings already exist (folks go fishing and swimming there) and as they are an artificial AwShit, environmental wavier ought to be easy (even if Moonbeam is an obstructionist – the Army Corp can take over…) The other problem is getting the stuff onto the hillside. The main road to the parking lot is now washed out and the slope is steep, so dozers and graders would need to make flat paths suitable to big trucks dumping rocks… Once that is worked out, then the road TO the place bottlenecks. There is a back road to the other side of the dam, so you could set up a one way circuit. Up the backside (shallower climb for loaded trucks… I did it on a bicycle…) then down to the unload point, then down the hill to refill.

    All that still leaves the problem of where to get mixed cement… The local supplies will mostly be regular driveways and freeways stuff. The freeway stuff is sometimes fast set (hours) but the regular construction stuff isn’t. I suppose a fleet of mixer trucks running that way from a 60 mile radius could be set up. That’s a 2 hour drive and hill climb, then an hour of position and pour, so inside setup time. Still, coordinating that and getting the right cement is an issue.

    For the main spillway: Looks to me like a small hole in the side toward the E.Spillway above the big break. This could erode under it and take out a large section. That has to be fixed with rebar and structural cement, so a major problem IMHO being ignored. The huge hole will take filling with boulders, then cobbles, then cement slurry. Weeks. THEN you can put on a topper of the spillway chute. IMHO not going to happen. They will just erode and destroy from that point down and attempt to prevent further erosion uphill with fill under the footer. This will fail. It might work long enough to reach summer and a full replacement, but not without more erosion uphill and more loss of spillway structure; especially if they don’t protect the uphill left flank (toward the E.Spillway where they have that leak AND the potential for the E.Spillway to undercut it.)

    It is a race between erosion rate of the main spillway and arrival of rain. Nobody knows the actual rate of either one.

    So lots of application of erosion slowing techniques, and lots of hoping…

  55. Larry Ledwick says:

    Great link on the 1861-1862 floods. We have the same sort of ignorance of past flooding here in Colorado. We have records of stationary thunder storms dropping 20-24 inches of rain in just hours causing massive flooding on normally dry foothills and prairies near Denver but most of the residents of Colorado have no clue of major historical floods.

    Floods like the 1921 Pueblo floods which raised river levels 15 ft above normal.

    Or the 1864 Cherry creek floods in Denver (cherry creek is normally a small creek about 15ft wide you can walk through with pants rolled up to your knees and not get your pants wet.)


  56. Larry Ledwick says:

    Interesting pictures and some background on prior efforts to get the emergency spillway slope improved and armored with concrete.


  57. pg sharrow says:

    4 days of dry, half over, followed by another week of rain, heavy and warm to start. People that are demanding to go home after this Non-disaster, will be even more resistant to the next evacuation order. The authorities have only 2 days 3 at most to get ready for the next onslaught of flooding from the vast overburden of water still in the mountains…pg

  58. E.M.Smith says:

    BUT But but bu… P.G.!!! It’s a DROUGHT!!!!

    /sarc; … of course…

    Yeah, they have little plastic bags of cobbles to drop in the erosion ravines with helicopters… when we need to see a line of dump trucks stretching for miles and cement being poured by the tanker load.

    Somehow I think it will not be enough…

    The present strategy seems to be “shore up the E. Spillway just enough to get through this coming week with 100,000 cfs down the R.Spillway and then figure out what to do”.

    Last week it was “use the E.Spillway so we can cut back the R. Spillway to get through this coming week and then figure out what to do”.

    Next week it will be “shore up that last awshit just enough to get through this coming week and then figure out what to do”… or it will be “Now were did I leave that old resume? And how much Do disguise kits cost, anyway?…”

    I really do hope that somewhere out of sight they have a room full of the best and brightest C.E. (Civil Engineer or sarcastically Cement Engineer…) folk they can find, with real soils maps and analysis, doing real math, and solving the real problem… ’cause with an absolutely full lake, a series of “Atmospheric Rivers” as what the present setup looks like, and 180% of normal snow pack, plus no working drain on the dam with the powerplant shut down; the only things they can use are both busted.

  59. Another Ian says:


    Helicopter footage here

    Scroll down to comment by DiDave Today @ 6:12 am at


  60. Jon K says:

    This seems to be a pretty good shot of the spillway https://pbs.twimg.com/media/C4ig8K_VcAA40hv.jpg .

    Looks like there’s some bedrock formations at the lower part of the spillway, but the upper 1/3 looks like it was built on fill material as well as the majority of the area between the spillway and the power house. I don’t think any of the upper 1/3 will be able to be salvaged as there was most likely some major undermining of the base and any attempt at repair will just create your next failure point.

  61. Larry Ledwick says:

    As I predicted they are working to allow evacuees to return home, probably with some restrictions or cautions to be prepared to leave on short notice etc.

    from twitter:
    Reuters Top News ‏@Reuters 15 minutes ago

    JUST IN: Evacuation near California’s Oroville Dam still in effect, but officials working on plan to allow citizens back home: sheriff

  62. Power Grab says:

    There are some images on Twitter of the days when the dam was being built. Here is a link to one:

    Here is another link:


    I don’t know if you can get to the images from those links, but there they are.

    I was wondering if you could tell anything about the bedrock from those old photos that were taken during construction.

  63. E.M.Smith says:

    A really nice overhead view form a helicopter prior to the Emergency Spillway washout:

    You can see them doing some emergency fast set concrete & rocks near the regular spillway

  64. David A Anderson says:

    The goal is a 50 foot drop by Wed or Thurs. Not seeing it depending on inflow.

  65. E.M.Smith says:

    Interesting… a quick search of Yutube for that press conference (which has a dozen variations to choose from when I posted) has found none… I wonder if they decided to have it removed, as it was fairly “no worries” and now that’s quite wrong…

    Or maybe I just need a better search as more stuff has shown up…

    Update: Found a replacement for the original. One from a pro-TV Station.

    Update2 14Feb: That one now gone also. Who is trying to erase the past?…

  66. David A Anderson says:

    This link gives a great idea of net change daily based on CfS flow for all the reservoirs…

    Click n the lake acrynem

  67. E.M.Smith says:

    The E.Spillway at full run with the roadway washedout:

  68. David A Anderson says:

    I looked at the video on my 80 inch UHD. At about a 23-minute park you get a really good picture the East spillway going over the burn to the relatively flat section where the other video showed the concrete gravel rocks and concrete being poured the two or three days before. Having a steep drop on the concrete section to a relatively flat Earth drainage area does appear to be a clearly horrible idea. I would like to see a picture of that same area today with the Lake lower then the emergency spillway.

  69. David A Anderson says:

    The other video showing the main spillway was quite interesting. The water at the break appears to be a lot cleaner then it initially was. Indicating that it is clearly down to the Bedrock now and hopefully the main spillway will not degrade further.

  70. E.M.Smith says:

    The briefing today. Actual talk starts about 30 min in.

  71. Larry Ledwick says:

    For comparison this is the Dillon Dam in Colorado built about 1963. The entire front face of the dam is covered with rock (pretty large rock about the size of microwave ovens and a bit larger). If it over topped there is no exposed soil to erode on the face of the dam.

    Then at the bottom of the dam is flat open space with ball fields for any water flow to run smoothly across with no natural ravines or other terrain features to encourage cutting of gullies before the water goes into the Blue River proper.

    Google maps and search for:
    39.622492, -106.063821

    My dad took me fishing here just as the dam was in the final stages of construction (nice sized trout in the spill way chute at the lower left of the dam face ;) )
    I spent a good deal of time scampering over that rip rap covered dam face hopping from rock to rock.

  72. M Simon says:


    Thanks. My guess on the engineering? “What assumptions do we need to make the construction come in at a ‘reasonable’ cost?”

  73. llanfar says:

    @John Silver A nice link to the creation (with dedication by Gov. Ronald Reagan) in the comments…

  74. E.M.Smith says:

    This has a nice embedded video of the aux spillway erosion that was the issue. But it is some homegrown video imbed so I’m not taking the time to figure out how to defeat it…

    The interesting thing to me is that the long erosion scar is traversing up to the LEFT or farthest end of the emergency wier / barrier. Essentially, the water was cutting a path around it to the shallowest end. Had that finished, it could then start destabilizing from the thinnest concrete section inward…

    Crafty stuff this water…


    I remember watching that train dumper in person :-)


    The engineering equivalent of the economist’s:

    Given these conculsions what assumptions can I draw?

    @John Silver:

    Yeah, disturbing.

    That is the same erosion scar seen with people for scale in that article link just above in this comment.

    It sure looks like weak sedementary deposits to me (and I did take geology classes in college…)

  75. pg sharrow says:

    @John Silver; It is “Bedrock”! my house is built on and in it ;-)
    actually semi-consolidated Lahar An ancient volcanic mud flow. about the consistency of rotten concrete made of broken rock, ground up ash and clay. often in strong and weak layers. You can dig in it with hand tools with some difficult. Very inconsistent in density and material mix. Not something I would want to withstand strong scouring after long exposure to the elements. When first exposed acts like a modest sand stone but after long exposure the binders “melt” back into clays that flush out and you have gravel and soil. Well they thought they had solid bedrock…pg

  76. E.M.Smith says:


    Yeah, I know that stuff too. Feels like rock until it crumbles like shale then softens like mudstone…

    I was hoping it had basalt lava under it like you can see at the scoured bottom of the regular spillway, with the concrete wall bonded to it, then backfilled to look nice. Now the photos make it look more like the wall was poured on semi-shale lahar / oxidized volcanic stone mix and figured it would never be needed anyway.

    It is looking to me like their only hope is the rock bag fill of the revines, top with dredger tailings to smooth, then loads and loads of concrete slurry poured on, and wait a week. Ought to be done by August…

  77. David A )Anderson says:

    E.M., your earlier link showed crews at the E.S. nearest the dam pouring concrete on gravel, boulder mix. ( This was part of the two day or so prep- work when the main spillway was shut off. Looking at that area it

  78. pg sharrow says:

    By August! YEAH, if it a rush job….LoL
    I see a series of faults as well, collapse along that fault line due to “melting” of the “bedrock” from water infiltration over many years. it runs from the river diagonal across the face of those overflows and under the north end of the dike and into the lake side. I have several of those, good soil and clay in them, crap on each side…pg

  79. David A )Anderson says:

    …Looking at that area in the last day it held up well A.F.A.I.C.T.

    Certainly with ten times the crew and three weeks time they could get a great deal accomplished.

  80. David A )Anderson says:

    I find it strange other reservoirs, such as Don Pedro, are not doing much larger releases

  81. David A )Anderson says:

    Curious, per the link above inflow went from 69000 CFS on the 12th to 14500 CFS on the 13th.

    This drop off of inflow is extreme. Are there other resivors above Oroville?

  82. David A )Anderson says:

    Scroll down for the best picture of the E.S. after the water lowered. 40′ cliffs where the road was.

  83. M Simon says:


    Some nice pictures and commentary by engineering geologists.

  84. Larry Ledwick says:

    Article on the evacuation and local response with a little on the importance of the reservoir to the local communities.


  85. Larry Ledwick says:

    Video from facebook that shows the deep erosion cut that took out the road.

  86. E.M.Smith says:

    Sigh. It looks like someone is really trying to erase that first briefing where they said, roughly, no problem, we will just use the auxilliary spillway… even the KCRA video now gone.

    I’ve got to find a video archiving tool….

  87. pg sharrow says:

    That wash out below the north end of the emergency overflow was caused by a FENCE some stupid Security Bureaucrat had installed on the lakeside of the dike! A cyclone security fence full of trash directed turbulent flow over the weir dike at that point…pg

  88. E.M.Smith says:

    I’ve added a profile view of the Emergency Spillway weir up top, for an original document referenced here:


    H/T to M.Simon for the link to that site.

    To me, it looks like what you see above ground is what you got…

    Which would mean erosion undercutting is a verry real possibility given the depth of erosion already demonstrated.

  89. Larry Ledwick says:

    From twitter:
    FOX31 Denver KDVR Retweeted
    KTLA ‏@KTLA 13m13 minutes ago

    #BREAKING: Blocked roads into Oroville reopened and evacuees can return home, officials say #OrovilleSpillway http://on.ktla.com/m4LtP


  90. E.M.Smith says:


    Yeah, that’s the ticket… The sun is out and it doesn’t have a week of torrential rain in that area for at least the next 2 days, so sure, send everyone home…. Rinse and repeat…

    I suspect it is the right decision, but they ought to have been sent back as soon as water was below the Emg. spill level and breech was not on the cards.

    The storm that arrives Thursday looks to rain for about a week and drop near 3 inches of rain in the Lake Oroville catchment.

  91. Larry Ledwick says:

    Unfortunately this process sets up evacuation fatigue where each time they call for an evacuation more and more folks will be reluctant to move. If that happens 3 or 4 times and then the dam fails you end up with a big casualty list.

  92. David A )Anderson says:

    If the main spillway holds they should be fine at 100,000 SFPS.

  93. M Simon says:


    That is some site isn’t it? Real engineers.

    A comment from there:

    I can imagine the structure being placed on the existing grade, especially since that’s actually the only method I’ve seen used on dam structures that size (and we already have the documentation to show that they were skimping on costs for this part, and on that subject, I had similar thoughts about that little wall at the edge of the parking lot. Oh, and that’s further logic against the weir being in a deep excavation. Why do extreme over-design on one part and extreme under-design for another?).


  94. E.M.Smith says:

    @M. Simon:

    Yep. Gotta luv it… folks not afraid of math and physics ;-)

    That particular comment caught my eye too ( I read all the comments…. yes, all the way to the end of page 14…).

    I’m trying desperately to recover memories from when I was about 10 to 15 years old, when I was visiting the construction and reading signs and such on a frequent basis (one of the few interesting things to ever happen in the area).

    The spillway was particularly interesting since it looked like more than a dirt pile ;-) and the boat ramp was a place to go fishing… so lots of eyes-on time, and just got to pull the memory bits back together.

    What I **THINK** I remember is that the big ripper cats were a hot topic in town (farmers who used large cats and underground ploughs to rip the thick adobe layers for orchards to get to the water table). And that the sil of the parking lot overflow was just on top of the rock in a shallow trench. The main concreted structure of the Aux Spillway was cast in place (they had a full concrete making facility built on site IIRC used to make the ‘toe’ of the dam too. It was formed on top of the ripped rocks, that were not red at the time. (i.e. not weathered to weak red yet, more a gray color below the rip) and that the Aux Weir steps up to smaller section as the solid rock area was higher.) All that in keeping with the speculation in that comment.

    I also remember [someone] talking about or speculating that in large emergency outflows the parking lot area would slowly erode out and take the lake down 100 feet or so to save the dam. Basically that it was a sacrificial drain plug. At lower flow, it would go over the weir and the ‘footer’ conducted it to the end near the weir and on down the ravine without erosion.

    but I don’t remember who it was saying it. Clueful workers, or local yokel making shit up…

    My assessment, from integrating what was read on the site, what I maybe remember, what I know of the local geography, and what I remember of my geology / chemistry classes is this:

    They built the Emergency Spillway as a sacrificial structure, on ‘strong enough’ rock, that has since weathered and aged to “not quite strong enough’. It was intended to take 5000 to 10000 CFS without significant injury for a day or two, but once water overtopped the parking lot area, it would start a slow controlled erosion letting out 200,000 CFS or so as the rock wore down. But now, with weathered rock, it will erode much faster, likely reaching 300,000 to 400,000 CFS as the hill erodes down to more competent rock about 50 feet down.

    I have this haunting 1/2 memory of “someone” in a “uniform” (perhaps park ranger green) talking about how the parking lot area would wash out in an emergency overflow but that the thing would stop eroding as lake level dropped and the erosion reached the harder rock layer (some feet) further down… I THINK it was a high school science field trip… I went over and looked at the square cement along the parking lot edge about 4? feet and thought it was pretty big and strong, but that the dirt could wash away… so could see it happening but taking time. But the big 60? foot tall or so cement weir would stay standing and acting as a weir as the water dropped below the top of it… then it would be a dam directing water out the parking lot end.

    But it is a broken and fractured memory from 1/2 century ago when I wasn’t paying much attention and just wanted to go fishing… just flashes, really, and some of the stitch together is likely being created to fill in missing bits… A reach too far for clarity…

    Oh well.

    From the present POV, I think they are dependent on the regular spillway not washing away before summer, and accepting that in any major use of the Emergency Spillway it will be as an emergency eroding plug for controlled lake release and expect flooding from Oroville to Marysville and 1/2 way to Colusa, but not a wall of water, more a rising tide as the plug erodes.

  95. Larry Ledwick says:

    E.M. that is exactly what my video link above at : 13 February 2017 at 7:15 am shows.
    They intentionally put a “soft plug” in one wing of the dam so if it over topped a small self limiting emergency relief would form as the water cut away the soft plug and dumped excess water.

  96. E.M.Smith says:

    Just watched the video.

    Yeah, same general idea. Couple of differences though:

    The Lake Oroville “plug” is harder material that gets both thicker and harder as you do down. I suspect it would stop eroding at about 100 foot elevation drop and with most of the water still in Lake Oroville. That natural V in the hill has hard base rock in it and the narrow area of lahar like fill gets narrower as you go lower (while water in the lake gets less too). It isn’t just consolidated fill like the coffer dam.

    The intent was to limit max flow to acceptable levels, then shut it off before the lake empties (but after the dam is safe).

    At least, that’s my opinion of it….

  97. Mr. Wonderful says:

    Hey boss, long time no hair graphs. New email, no more ruhroh via comcast.
    I thought you might enjoy this ;

    Click to access Rogers-Paterno%20Overview-March%202008-compressed.pdf

    This has some levee height info and explanation of the downstream drainage.
    Much less interesting, but at least a few data points of flow rate vs channel fullness.

    Click to access a425175.pdf

  98. Larry Ledwick says:
  99. Mr. Wonderful says:

    The levees pdf is very interesting. They tend to fail somewhat after the peak rain.
    THey are like long linear earthen dams, of various construction including river silt.
    Anyway, I undersold it, but that is a wonderful history of yuba river flooding and underlying geology.

    The Army Corps did do an apparently diligent job on the lower Sacramento levees, assuming they were not prevented from fulfilling the contracts.

  100. Larry Ledwick says:

    Anyone tracking current status of the Oroville Dam situation?
    Current forecast from Nat Weather Service

  101. E.M.Smith says:

    I’m paying attention to it. I still have a lot of connections to there… and right now I’m only about 210 miles from it so get substantially similar weather.

    The weather has hit. Strong winds here, and heavy rain in places. Prediction is for about 1/8 of an annual average (where I live) in this one storm, and this isn’t the only one in the chain. It is supposed to be way worse in So.Cal where somewhere near Santa Barbara was expecting one YEAR average rain in this storm.

    The last storm missed us (it was supposed to be a gully washer but was just a ‘bit of rain’ during the night. I don’t know if it tracked north, south, or faded (the weather map on the local news made it look like a bit of a fade and shift north)).

    This one has the feel of a ‘cold one’, so ought to dump a lot of snow. That would be a life saver (literally). THE ‘bad thing’ to panic over is a warm pineapple express melting the landed snow.

    As of now, I think the damn will handle this just fine. What happens if we have 4 or 5 days of this is unclear (“try again later” ;-) but it will be touch and go then.

    It is supposed to let up later this afternoon (so about late afternoon / early evening in Oroville) then have a nice late afternoon into tomorrow, then repeat the whole process early next week. As long as the coastal end keeps whipping up and down the coast, things will be fine. If the “atmospheric river” gets stabilized over the Feather River catchment, they are toast. Supposedly it is So.Cal getting the worst of this one, but “things change”… so we will see. Right now it is a lot of wind and only moderate on the “gonna maka flood” torrent scale… but this is supposed to be the backside of what went through last night.

    The Big Day will be about next Thursday when the whole chain of storms is over and the catchment has had time to drain toward the lake and the sun is out on the snow…

  102. LG says:

    Ryan Maue posted this map on Feb 15.

  103. David A says:

    From 7pm Sunday night, to 7am Tues morning will be the heavy hit with the warmest and wettest part of the next storm. The mountains in the Oroville water shed are expecting about 6 inches in that 36 hour window with 100 percent chance of rain throughout, peak precipitation being 4am Monday to 7 pm Monday, with about 6500′ snow levels.

    I do not know how long after for max inflow into Oroville resivor. Likely about 24 hours.

  104. E.M.Smith says:

    Wind seems more from the south west now… this is ‘not good’ as that’s the warm pineapple express direction.

    This needs to be monitored and checked… I’ll be back later.

    Well, I thought I’d hit “post” on this, but it’s still sitting in this window… so I guess not. Since then I checked the weather maps and it was the center of a big cyclonic storm. We get those on the California coast. Kind of like tropical storms, but colder. As the core moved near me, the wind shifted direction with it. Then through the evening we had the banded rain more. Now, next morning, it is gray and overcast as we are on the backside (and waiting for the next one).

    Similar weather maps showed this continues (waves of rain) until about Wednesday. Predictions for part of the Oroville catchment look like (per the map) they range from about 7 inches to 11 in some higher elevations. One hopes it is snow there.

    The Oroville thread will likely be most interesting about next Wednesday to Thursday…

  105. David A says:

    Monday T at 5700 expected to be about 40 F

  106. p.g.sharrow says:

    Nearing midnight and the next front is due here above Chico. We are promised 5+ inches of rain over the next 48 hours and warming temperatures. Today we had 1+ inches and a fairly warm day, streams already very high, nearly flood. There will be a LOT of WATER in the rivers by Monday as this Pineapple Express Train sags south. Many of the people that evacuated to Chico from the Oroville area have stayed in Chico rather then risk going home. It appears that the storms for late next week are from the Northwest, much cooler and dryer.

  107. Mr. Wonderful says:

    Here’s a nice map of the channel capacities for the various waterways;

    Click to access sac_flow.pdf

    and an overall schematic view;

    Click to access sac_sj_schematic.pdf

    and here’s the realtime of the flows and river stages; Red is Above Flood stage.
    It also has the latest lake levels for Oroville, etc. One stop shopping…
    Remember to refresh it.

    OK, here’s the Shasta view;

    Here, the National Weather Service is candid about model scatter;

    “Forecast models have continued to struggle pinpointing the axis of
    heaviest precipitation with this particular atmospheric river,
    with various runs and models highlighting every location from Big
    Sur to the North Bay with intense rainfall. Model trends begin to
    emerge amongst the noise, which have given higher confidence than
    any single model alone could do. These trends suggest that
    for late this afternoon/this evening, rainfall will initially be
    advected inward on an east to west axis and widespread along the
    coastal ranges from Big Sur to the North Bay with no clear stand
    out. Next, the plume will begin to narrow and intensify between
    10pm and 4am overnight as it interacts with a descending low to the
    north and ridge to the south. As this band intensifies, the axis
    will shift from an east to west setup to southwest to northeast
    axis. This is important because it will likely enhance the
    orographics of this event and further increase anticipated rainfall.
    This narrow, intense band has been trending towards a landfall
    somewhere between the coastal Santa Cruz mountains and North Bay,
    with a mean landfall zone over the I80 corridor (Golden Gate Bridge
    to Sacramento to Northern Sierra Nevada). Confidence is moderate to
    high that the heaviest rain will fall somewhere in this zone.

    Forecast precipitation values have been wildly varying run to run
    and model to model, so confidence is not as high on exact storm
    total precipitation values. That said, the afternoon forecast
    package has been built around the most likely scenario previously
    discussed. Given that scenario, here are how the forecast values
    have played out, from least to most. Inland San Benito/Monterey
    county will be rain shadowed by the Big Sur range, 1.0-2.5″. Santa
    Clara Valley, partially rain shadowed, 1.5-3.0″. Inland East Bay,
    2.5-4.0″. Inland North Bay and San Francisco Bay Shorelines,
    3.0-5.0″, locally higher if main intense rainfall band stalls
    aloft here. Big Sur and East Bay peaks and ranges, 4.0-6.0″.
    Coastal North Bay 5.0-9.0”. Coastal Santa Cruz and San Mateo
    ridges, 5.0-10.0, locally higher if main intense rainfall band
    stalls aloft here. Depending on how far north of south the main
    intense rainfall band wobbles over the next 24-36 hours, one or
    more of these locations could see locally higher or lower amounts.
    A flood watch is in effect for all areas in anticipated of this
    excessive rainfall through the coming days. “

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