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

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


Click for video

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

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

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

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


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

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


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

We’ll update this story as more is known.

Here is a historical video for perspective:

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


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

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

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

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


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

 orovilleUpdate 3: Oroville water level tops 900 feet, water will start flowing down spillway

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

        Therefore it would be opposed by the Green Machine.

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

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

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

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

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

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

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

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

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

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

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

  13. 135k cfs in. 65k cfs out. Effective 70 cfs detained.
    Imagine what the downstream river would have looked like @ 130 cfs w/o the dam. Dams are good.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  36. re: “As of 11 AM, they were letting out 65,029 CFS, but have a staggering inflow of 132,107 CFS, more than double the release rate:
    According to the short documentary I posted earlier (The Birth of he Oroville Dam) at the end of the other thread, the maximum discharge rate upon opening the (IIRC) eight 30 foot ‘gates’ is on the order of 250,000 CFS …

  37. I see the problem. The water runs down the spillway and clearly circles around back to the reservoir (a la M. C. Escher).

  38. They will probably sacrifice the spillway to save the dam…breaching an earthen dam can be fatal for the dam….it’s too dangerous to have no freeboard on an earthen dam. The outlet penstocks won’t be able to draw down the reservoir level very quickly. Another large storm may exceed the spillway capacity. That would mean the dam breaches.

    • re: “They will probably sacrifice the spillway to save the dam”
      Ah, um, uh, there is that other ‘thing’ that acts as a safety overflow that will begin ‘passing water’ when the ‘pond’ reaches about the 901 foot level …

      • Well, u.k.(us), they can open the ‘sluice gates’ a lot wider it appears, upwards of 250,000 CFS worth. At 135,000 CFS present release rate they are only a little over half way there!

    • Should add that both of those are eastbound main arteries out of Sacramento towards NV.
      80 goes north of Tahoe, 50 just along the south side of the lake.

      • On highway 17 there have been several slide including one big one that occurred about the time spillway was damaged. While crews were working on clearing the slide to reopen highway 17, A section of highway 37 “dissappeared”. A large part of the hill slide away taking the road with it. They may have to build a bridge to fix it. A nearby reservoir was undergoing modification to address earthquake concerns and is currently the lake has a 50% fill limit imposed. Right now the lake is at 90% with the spillway open.
        All across the state there are slides, rockfalls, and other damage occurring the reads. I suspect the Oroville damage was due to a slide that no visual inspection would have pewsixrws ir.

    • Easy. There are communities in CA where you can be fined for collecting rainwater….on your own property.
      Best check with Central Planning first, unless you know a party member.

    • Maybe Soros will offer to pay a dime a bottle?
      That’d be more useful than paying others to incite the minions to break stuff.

  39. Another Sultan Sea in the making? Gotta had it to those Cal Engineers!
    No doubt Jerry Gov Moonbeam will be blaming the situation on …. TA DA … Anthropogenic Global Human Warming and saying … “We will build our own Phuck’n Damn!” … upon which a Cal EPA attorney will tap Jerry on the shoulder and say … “No no NoOOoo”.
    Ha ha

  40. There may be an interesting side effect to this event. We live about 5 miles from the Canyon Lake Dam and spillway in Texas. In 2002, a major month long rain event nearly wiped out the spillway here. The result, though, is a mile long walkway through 110 million years of geologic history. There are occasional public tours which start out at the top which is present day. As you progress down through the spillway, the geologic history of the Balcones Escarpment is exposed, terminating at the bottom, 110 million years earlier. It is a quite interesting tour.

  41. “Climate change will lead to more dry years, more wet years, and more average years”
    Wikipedia California Drought
    Did a prankster sneak that in or what.
    Now when will the MSM which still supplies millions with their news go back and review stories of “endless drought”

    • Reminds me of the UK Met Office.

      Met Office Initial Assessment of Risk for Winter 2010/11
      This covers the months of November, December and January 2010/11, this will be updated monthly through the winter and so probabilities will change.
      3 in 10 chance of a mild start
      3 in 10 chance of an average start
      4 in 10 chance of a cold start
      3 in 10 chance of a wet start
      3 in 10 chance of an average start
      4 in 10 chance of a dry start
      Summary: There is an increased risk for a cold and wintry start to the winter season.
      Looking further ahead beyond this assessment there are some indications of an increased risk of a mild end to the winter season.


    • Well, what do you think, it is a true statement!
      If there have been until now x, y and z years for the 3 cases mentioned, there will be x+a, x+b and x+c years sometime in the future in a+b+c years…. Easy provable…

      • Math is great until you include the six W’s:
        Who, What, Why, When, Where, and hoW. Then it gets sticky.

    • That’s a hoot! It’s one of the few things they can say that I agree with! Unfortunately, it says absolutely nothing, as even without climate change those things will happen. But the climate is changing (as it always has), so there is nothing to argue about. And there will be more dry years, more wet years, and more average years. This guy must be a politician. Or a lawyer. Maybe both.

  42. All signs point to an epic year of potentially biblical floods in california.
    Mostly it’s the earliness of the accumulations.
    The earliness of the Oroville reservoir near filling is significant.
    The prior near filling was 82-83 water year when the filling did not happen until June 1st.
    see here: https://cdec.water.ca.gov/cdecapp/resapp/resDetailOrig.action?resid=ORO
    Imagine the potential for the enormity of snow/water accumulation ahead as the rest of February and all of March, April and May are added to the current abundance.
    I recently asked the California Department of Water Resources about how rare the earliness of the snow/water equivalency accumulation is.
    I see that the current status is reported in two ways. http://cdec.water.ca.gov/cdecapp/snowapp/sweq.action
    % of April 1 Average / % of Normal for This Date
    STATE Data as of February 2, 2017
    Average snow water equivalent (Inches)
    Percent of April 1 Average (%) 109
    Percent of normal for this date (%) 173
    I wonder how early this accumulation is?
    Or rather how unusual or rare is it to have 109% of April at the beginning of February.
    Is this amount, at this early time remarkable? Is so how much so?
    There must be data to determine the significance.
    With 2 more months of routine, potential & likely additional accumulation I would be interested in knowing how significant the current 109% of April 1st Average is.
    Hi Steve
    Such high readings (snowpack water content) this early in the season are significant, but not unprecedented. See the highest and lowest February 1 readings below (since 1950). Obviously, weather conditions in California vary greatly – not only from year to year, but from day to day. So the snowpack that normally provides about a third of the water we use in California is off to a great start, but we have to keep in mind that our weather can turn from wet to dry on a dime. It’s too early to know where we will stand come spring when the wet season is behind us.
    I hope this helps,
    Highest snowpack water content as a percentage of February 1 average:
    1952 267%
    1969 230%
    1995 207%
    1993 200%
    1956 193%
    Lowest snowpack water content as a percentage of February 1 average:
    2014 14%
    1963 21%
    1991 21%
    1976 22%
    2015 23%
    1977 25%

  43. According to news report, they are going to dial down the spillway release a bit because it’s so damaged they now fear undermining the power transmission line towers, even though they removed the wires yesterday and today.
    This means they say that there still may be water going over the emergency spillway in the next day.

    • I was just looking at the dam web site and they indeed did cut the outflow to 55000 CFS at 8 PM. Inflow is decreasing slowly but remains above 100000 CFS. Distance to the uncontrolled spillway is down to 1.4 feet.
      If this data is accurate, the spillway will start flowing in about 4 hours.

  44. In August of 1975 there was an earthquake near the Oroville dam. Rapid emptying and filling to allow repairs to the generators were implicated in the earthquake. What will rapid filling from nearly empty do today ????

  45. 899.44 ft. at midnight. For the last 8 hours, the water level has risen at a nearly linear rate of about 0.27 ft/hr. It seems unavoidable now. The spillway will be topped by 3 a.m. PST
    Adding insult to injury, it looks like the dam got a little more rain (0.16″) this evening.

  46. Nope. It will flood the emergency spillway…. They’ll have to slow the water in the other spillway otherwise they are going to have a gorge there. That water will be just eroding the hillside.

  47. It is quite interesti g that their prime concern in using the “emergency spillway” (code for “low point other than the dam wall”) is the soil it will wash into the river below.
    Seems to be plenty of soil already being washed into there from the non-emergency spillway.

    • the concrete spillway is basically washed down to bedrock now. The emergency spillway has a huge amount of soil that will be washed into the Feather River.

    • The gravel from that soil will settle in the channel of the river downstream of the dam, reducing the capacity of that channel, making any local flooding worse. As there is a low head dam just downstream that gravel will not be able to move farther downstream. In a natural channel the gravel would eventually spread along the channel to little future effect. With it prevented from moving it will have to be removed to restore the capacity of that channel.

  48. as long as inflow exceeds outflow, the emergency spillway will release water and the lake level should not get much above 901 ft. The flow down the emergency spillway looks like it could hit 30-40,000 cfs, which can be compared to the 55,000 cfs the concrete spillway has been handling overnight. That will cause a lot of erosion.

  49. Well their rosy projections have turned out to be bunk if this is correct. Says they had to shut down use of the primary spillway due to erosion of the earthen bank supporting the dam. So the emergency spillway will have to be used and their already working on clearing what vegetation they can while they can. This guy also claims there is a lot more water coming than what I had read about before. It is now a real emergency it seems moving towards a possible disaster.

    • They’ve been clearing vegetation and other possible large debris objects since Wednesday.
      They’ve also been spraying cement onto the bed of arranged boulders along the emergency spillway.
      They also removed the transmission wires from the towers. Looks like they followed recommended protocol as soon as the numbers became obvious.
      This is fascinating.

    • “spillway is unuseable” ???
      Right, so where is 65000 CFS of water going now, if it is “unusable”. Typical youtube BS merchant.

  50. Cavitation can produce dramatic effects. Pages 5 and 6 here talk about a famous failure at Tarbela Dam in 1974.
    Talk of rebar prompts my favourite picture of it and a picture of its engineering genius Ove Arup on the finished Regents Park Zoo Penguin Pool ramps in 1934 (when engineers dressed properly, wore hats and smoked pipes).

    • Considering those ramps were only supporting their own weight (and a few penguins) that is some serious rebar work! I imagine Ove Arup would be appalled if he could watch the videos at the beginning of this post.

  51. Emergency spill way constructed in the 60’s and never used before will, after a few days of prep, have to be relied upon for days if not much longer? Is that what the situation is right now?

  52. It is the relentlessness, there is no way to stop it.
    Now it is gravity stored hydro vs the underlying geologic structures.
    Gravity will win eventually, it’s just a matter of how much scouring will occur.

  53. Just by looking at what’s going down I’ll make a prediction:
    They’ll abandon the damaged spillway and build a bigger one on the other side of the emergency spillway. That massive new erosion at the lower part of the current spillway is just too scary close to the tallest dam in the United States holding back the second largest reservoir in the state.

  54. Questions, not a challenge, I’m not an engineer. Why does a spillway need such a long run that is built over fill? Couldn’t the top of the spillway and associated gates be built into the bedrock with no long concrete run at all? Downstream flow would run over bedrock. Thanks in advance for any response.

    • My guess is that it is cheaper to fill with concrete than to cut bedrock.
      At least the bedrock will be jet cleaned ready to repairing the spillway !

      • Exactly. Drill and epoxy in #18 (2.25″) epoxy coated rebar and make a continuous grid. Then simply pour in concrete. A large heavy aggregate would work best I think.

  55. I’m wondering what officials are thinking with regard to Lake Isabella. The dam on this reservoir is ranked “most dangerous” in the U.S. – the nominal capacity is 590K acre feet but because of weakness in the “Axillary Dam”, the new limit is 350K to 375K AF. At the start of January it was at 95K, it is 296K this morning, 73,000 AF being added in the last 7 days. The outflow has been in the 700 – 1100 CFS range all this time, which is a small fraction of what could be let out. Unless they open the gates the reservoir will reach 350K AF by next weekend.
    The inflow has been in the 5000 – 12000 cfs range for the last week. With warm weather next week I don’t thing this is going to decrease much, if at all.

    • They had 10 years to work on it and did nothing. 10 years of clear skies and a near empty reservoir that they could have dug down below the dam base level and greatly increase the capacity safely, then use the soil for repairs to the damn and increase the base size.
      This is so typical of California. A disastrous, incompetent government.

      • re: “that they could have dug down below the dam base level”
        Do you understand that the spillway, that LONG, wide ribbon of concrete, rests on the down-slope of a BIG hill (small mountain) comprised of ROCK?

      • Perhaps,
        Anyway, the job of repairing the Auxiliary Dam was suppose to start this year, The current build up of water just seems to go against the plan.

      • @_Jim : A hectare metre of water (aka 10,000 m^3) weighs 10,000 metric tons. Without looking anything up or using a calculator can you tell me how much an acre foot of water weighs? Didn’t think so.
        Nationalism is a pretty stupid way to choose a unit system.

      • @_Jim: Actually ignore my comment. It is Sunday and my brain is down for repairs.You thought I was trolling and countertrolled. Fair enough. You guys don’t need me to tell you that your units suck. I’m amazed that you put up with it.

      • Ian H February 11, 2017 at 5:44 pm
        ‘Nationalism is a pretty stupid way to choose a unit system.’
        Which, of course, ironically, is why Napoleon chose it and why it’s been partially enforced in UK so that selling (straight) bananas by the pound (not kilo) means jail time. When I lived in Germany we used to buy cheese at the market by the ‘pfund’ which was rounded up to 500g.

      • Ian,
        To answer your other question … 10,000 X 1.1 = 11K tons (english or short). [ya, I used K …)
        Get back to me when you convince the rest of the world to use base 10 for the most used measurement and longest used measurement system.

    • “Acre-feet! In 2017! Unbelievable”
      But if it makes you feel better.
      1 AF = 1,238 m^3. Oh wait, depending on YOUR convention that might be 1.250 m^3. But to be clear, one thousand two hundred and thirty eight cubic meters.
      Actually I do know how much an AF of water weighs. it takes me about 5 seconds to figure it out…of course in pounds.

    • And I was in too much of a rush to actually answer the question … 1360 tons (31 X 44)/, but why would anyone care

  56. The DWR website table for Oroville Dam is lacking a column for the volume of water outflowing on the emergency spillway. It never needed one before. The table would be more informative if this column existed.

    • Simply subtracting the tables outflow from the inflow would seem to give that result at this point. But estimating the inflow based on river height is just a fair guess at high level flows. Measuring output over a weir or through a gate would be much more accurate. So with less than 6″ of water crossing the emergency spillway (weir) I question the inflow number as I doubt that there is over 25,000 cfs flowing over it at this time. I don’t know the length of the overflow on the weir but the pics/video looks like much, much less.

      • It looks like the lake topped out at 19″ above the emergency spillway at midnight last night. Next weekend might be a different story with the new storm coming.

    • “Flows over this secondary chute will likely range between 6,000 and 12,000 cfs, the California Department of Water Resources said.”
      “Inflows decreased Friday and into Saturday morning to 83,600 cubic feet per second, of 10 a.m., water officials have also decreased outflows from the damaged spillway to 55,000 cfs, according to DWR.”
      Either DWR is lying or they got the quotes wrong. Q in = Q out so 83,600 cfs into the lake has to equal the flow out of the lake. 83,600 – 55,000 = 28,600 cfs over the emergency spillway at equilibrium.

      • It’s not yet in equilibrium. Each hour the new data shows the water level is still rising, indicating the inflow is still outpacing the combined spillway outflows. The emergency spillway volume will therefore keep increasing for a while longer.

      • “83,600 cfs into the lake has to equal the flow out of the lake. 83,600 – 55,000 = 28,600 cfs over the emergency spillway at equilibrium.”
        I’m not a hydrologist so I may be wrong on understanding in/out flows and lake volume. It seems to me that “a has to equal” statement assumes that the lake must be a hard sided container. A better analogy might be a balloon. As a fisherman and boater I’ve seen that, as water rises in a lake, some of the the water gets spread out into all the low areas in the terrain. Sometimes there is great fishing in all the newly flooded stream inlets, flats, and around newly flooded structure as well as pinch points between newly created islands.
        Have I missed something?

  57. As soon as the first 6 feet of marina dock is installed, or the first 6 feet of waterfront mansion footing is poured, the purpose of any previously important flood control lake and dam is destroyed.

    • It’s the tallest dam in the US but the water is right at the edge of the parking lot shown at the bottom left. That’s a lot of water. Now my question is what underlies the surface. Is it bed rock? If so what kind and how porous? The primary spill way is not going to be fixed overnight and thus the emergency spillway will have to be relied upon to for some time to come it seems. I’m no engineer but I have seen what a powerful flow of water can do and how quickly it can erode away seemingly solid substrate. It all seems rather dicey to me.

      • “The primary spill way is not going to be fixed overnight and thus the emergency spillway will have to be relied upon to for some time to come….”.
        That’s an interesting point. As I said above it would not surprise me if they built a new concrete spillway on the north (opposite) side of the current one in relation to the dam, which would also put it on the far side of the emergency spillway. I’m fairly sure they don’t want to undermine that north shoulder of the dam any further. If they really do rebuild the spillway at its current location, that’s going to be one heck of a lot of fill to replace, but then I have no expertise.
        As for the emergency spillway being “relied upon” going forward, it can only be relied upon for what it is, a spillway for when the lake maxes out.

      • After the spring rains, summer flows can be accommodated by the power generation spillway in the dam itself, giving a short time for repairs.

      • Chris 4692
        It is my understanding that this reservoir, like many others there, typically top out at their highest level during the spring thaw. And yet here we are well before that thaw with this emergency spillway being used. This during a year when snow levels in the mountains have been tremendous. With more rain forecast there is a potential that a warm front with rains could result in both rain run off and melt run off from that snow pack making things much worse than they are now. Who knows what is going to happen! But there sure seems to be a potential for a worst case scenario of massive flow over an extended period requiring that emergency spillway to be used a great deal of the time right through spring.
        It is obvious already the salmon and smelt numbers in the river are going to take a big hit. Let us hope that is the extent of the damage.

    • at the top of the picture is the dame . The middle is the main damaged spillway. The field between the parking lot and spillway gates IS the emergency spillway. The bedrock in the hill is likely granite. But I suspect that it is heavily fractured. Over the bedrock soil and loose rock. With water now going over the emergency spillway There is nothing they can do other than watch it. and hope the inflow drops.

  58. Obviously the early in the water year filling of the reservoir may be a very exacerbating issue if February, March and April produce additionally significant rain and snow.
    If overflow on the never tested emergency spillway persists over a long period of time it will be tested big time.
    Who da thunk such a problem with so much water would so quickly develop in a state so parched with irreversible drought and a “peak water” crisis?
    Peak water is defined in a 2010 peer-reviewed article in the Proceedings of the National Academy of Sciences by Peter Gleick …….

  59. The next 15 day forecast is ominous. Starting Wednesday there could be a week or more of rain. If as much rain falls as I fear, you will see in excess of 150,000 CSS going over the emergency spillway by next weekend. DWR and fake news media are downplaying the seriousness of what is transporting. If worst forecast comes to pass, you could see failure of concrete cap of emergency spillway lip. If that goes, it threatens the regular spillway gates and after that, the dam itself. The power of huge amounts of flowing water can’t be underestimated.

    • Hopefully temps will stay low enough to avoid the added runoff from washed-away snow.
      A few days ago it really warmed up during a heavy part of the storm – it was raining at Mammoth (base lodge 9,200′) – but that didn’t last long, it’s back to 24 degrees at 2pm and snowing (they’ve gotten eight feet since Monday). Right now they look on target to beat the biggest snow year since they began measuring in 1970 which was 668″ in 2010/11 (lowest ever was 94″ in 1976/77).

  60. Oroville Emergency Spillway activated.

    “Water blasted down the fractured main spillway of the Oroville Dam and crested over an emergency spillway early Saturday, as a local resident described spillway flows in earlier years, when the Feather River flooded. Peter Hecht The Sacramento Bee

    How NOT to design spillways. See Glen Canyon Dam overflowing.

    FYI: In that 1983 scary spring scenario, the Glen Canyon Dam had exhibited poorly designed cavitating spillways and strong structural vibrations. Essentially, the interior of the dam was humming with ominous sounds and an imminent catastrophe was truly in the making––with no sure way of avoiding the disaster. There was, in short, an inability to bypass enough floodwater in the event of a major flood. Engineers, like workers who manned the front lines, will tell you they were dam, damn lucky to have prevented a worse case scenario. Indeed, after the proverbial storm had passed the spillways were redesigned to reduce or eliminate cavitation damage caused by the massive flooding by designing air slots inside the tunnels. Hence, the revision eliminated a possibility of the dam being completely undermined via erosion of the spillways, while effectively reducing the danger of the dam being over topped. Overtopping also abets erosion of the dam abutments. Siltation, degradation of concrete and reinforcements, spillway operational problems, and unstable dam abutments are also listed as key factors that may affect the safe operation of this or any other dam.)
    The worst damage was what you could not see from the outside. . .the intake tunnels and how cavitation just about toppled the entire structure:

    171,000 dead from Incompetent Central Planning
    The Forgotten Legacy of the Banqiao Dam Collapse Eric Fish February 8, 2013

    Summary: In 1975, after a period of rapid dam development, a perfect storm of factors came together to topple Henan Province’s Banqiao Dam and kill an estimated 171,000 people. Today, on the cusp of another dam-building binge, some worry that factors which led to Banqiao’s collapse are re-emerging.

  61. I just noticed a curious thing. This whole adventure got me looking at the surrounding dams on Google Earth and I found that the non-earth dams have been “blacked-out”. There’s a fake structure overlaying where the dam is supposed to be.

  62. Once again skeptics, who pointed out that California climate is notable for extremes of drought and rain are proven correct. Climate true believers, who encouraged negligent flood control maintenance are proven, once again, to be wrong.

  63. It’s crazy that an emergency spillway has to be cleared of power lines and vegetation before it can be activated. Proof that they never thought they’d have to use it, just there for ‘regulations’.

    • re: “to be cleared of power lines”
      I think this part just might be bogus; I just reviewed video taken this morning and the HV transmission towers in the vicinity of the main spillway and emergency spillway are still in place.
      Were there low voltage ‘distribution’ lines on ‘phone’ poles close in that were removed? Something used to power street lights or other stuff up near the service roads around the spillways?

    • I saw one video today were they trucked in a buch of boulders and placed them at the bottom of the emergency spillway. Then they poured cement over the boulders. Hopefully the emergency spillway will not erode its foundation.

      • The emergency spillway via google earth is over 50 ft high. I hope that it maintains its integrity. Also at the far end, it looked like white water forming around the end of the spillway…All they can do now is watch…

      • they left the towers. i saw a news video where they were helicoptering workers onto the towers to disconnect and take down the lines.

    • The water is pooling behind the access road, they should have bulldozed it before leaving. If the ground is soaked enough there could be a big mudslide that blocks the river below. That is a pretty steep slope.

  64. Is this spill a result of a high reservoir level that would normally be lower? The thinking being drought conditions save the water as it will not rain or snow heavy again. Can Gore be sued if any damage occurs? Brisbane flooding was a result of not lowering the reservoirs enough, also thinking it will not rain heavy ever again.

    • Oroville reservoir was almost empty last year. Even in drought year to reservoirs reserve some storage volume to minimize flooding down stream. All this was done at Oroville. But it didn’t mater the Lake filled up due to record inflow. From my reading the dame has 2 generators and two diversion tunnels plus the main and emergency spillway. The Lake has been this high since the dame was completed.

    • Appears to be a dated video from a day or two ago, given the content.
      Also note: They are taking measures to PROTECT the transmission lines, not remove them.

      • According to multiple sources the towers of course are still there but some of the the cables in certain sections have been removed. At a press conference a reporter asked if this would cut power to anyone and they said no, it would just be re-directed between substations.

      • Well maybe they did remove a couple towers – I just saw this on-line:
        OROVILLE — Pacific Gas & Electric crews and contracted helicopter operators to dismantle and remove two transmission towers in the path of an emergency spillway at Oroville dam Friday.

      • Remember – this hill is strewn with multiple paths of transmission towers so just because you can still see towers and cables does not mean some were not removed.

      • re: but some of the the cables in certain sections have been removed
        “Poles and wires” (quote from the video) do not equate to transmission lines and towers which connect the power plant to the grid. The removed poles were down near the Feather River when the spillway intersects.

      • re: “OROVILLE — Pacific Gas & Electric crews and contracted helicopter operators to dismantle and remove”
        1) Press report, subject to error.
        2) The DWR folks, whom I saw with my own eyes and heard with my own ears tell a different story.
        3) DWR folks STATE that the power plant MUST be grid-connected in order to ‘discharge’ water via the power plant..
        Again, review the video for those details.

      • And at CNBC:
        “Cal Fire crews cleared a hillside area near the dam’s emergency spillway of trees, rocks and other debris to reduce potential debris flows downstream. Crews from the local power company, PG&E, removed several electrical lines and with the help of helicopters moved two transmission towers from the path of the emergency spillway.”

  65. A lot of pressure now on the narrowest part of the dam. Was it 1997/98 last time it was this high? I hope they didn’t forget to maintain that upper part during those 19 years.

    • IR Ha never been this If I recall correctly it got to 98% capacity. Right now it is probably at 101% or more. This is the first time the emergency spillway has ever been used.

      • ALTERNATE NAMES: They aren’t calling it the “emergency spillway” anymore. As of this afternoon, they were calling it the “auxiliary spillway”. Somebody with a big salary clearly earned their keep.

  66. I just saw a DWR official say that based on current inflow and barring any more rain (which they don’t expect until at least Wednesday) the emergency spillway overflow should last 35-50 hours.
    No idea what happens if they have to shut off the damaged spillway.
    I just saw an afternoon shot of the emergency spillway and boy is that water muddy.

  67. This article needs an update 3. The emergency spillway will be overflowing for up to 56 hours. It is 2 feet above the emergency spillway level. Let’s hope it holds its integrity. A chunk of cement displaced on the emergency spillway will cause mucho agua to be released from the reservoir, just like from the damaged spillway…

      • Even if they have to shut down the main spillway they still have 2 diversion tunnels and the generator. So they can still drain the lake but if the river flow risses again after another rain store they won’t be able to keep up withe the inflow and the lake will fill.

  68. The film of the very muddy water from the Emergency Spillway dumping into the Feather River clearly shows numerous full grown trees in the E.S., which were not removed prior to the overflow starting. It is a puzzle why this spillway has not been maintained over time as an open course with no trees, given its importance to the safety of the dam and everything down stream from the E.S.

    • Indeed. And a smooth, concrete surface over the top quarter or so. Should have been riprap and concrete and boulder diverters. Each sending cubic feet of water into the atmosphere or disrupting the general flow. Aeration and chaos would dramatically slow the concentrated power and actually benefit the ecosystem.

  69. I don’t understand why they were/are clearing the spillway of trees, etc.
    What is the problem if the dam overflows and there are trees in the spillway?
    Surely they will just be washed downhill and then flushed downstream?
    How is this any different to normal spring runoff which always contains fallen trees and other debris?

    • The way it was explained by DWR is that the less debris in the water at this volume (and resultant increased energy), the less chance for damage to structures e.g. bridges downstream.

    • The problem with trees is that they get stuck at the next obstacle downstream, in this case it would be the small dam just north of Oroville. If that dam were to become clogged with trees, it would quickly become very dangerous and they would have a real emergency in Oroville and beyond.
      This happen near me a few years ago. They were using backhoes and cranes, at considerable risk in the raging river, trying to pull the trees off a small dam. To no avail. Eventually the dam broke and everything downstream got wet. Nobody killed, but a whole section of town knee deep.
      For the sake of the people living there, I really hope the DWR has this under control and if they need Federal help they should ask for it now.

      • I’m not trying to be obnoxious here, but I am trying to understand the mechanics of the issue.
        Assume that a whole bunch of trees have been washed up against a dam wall. Would not water pressure hold them in place against the dam? And how would this be any different to just water pressure against the walll? Ie: how does the fact that trees are applying the pressure change the hazard? Why do they need to be removed?

    • There is a holding dam just downstream. If this fills up and/or the outlet is blocked it could be nasty. My guess is that they did not remove the trees to avoid erosion.

  70. It took Trump three weeks to end the global warming that caused California’s drought and to fill all the reservoirs.

  71. More on clearing of the emergency spillway from the Sac Bee:
    “Saturday morning, helicopters flew back and forth over the dam area, as Pacific Gas and Electric crews worked to dismantle cables and electrical components from electrical towers on a hillside adjacent to the main spillway, concerned that they, too, could be dragged into the channel by the crashing flows.
    Denny Boyles, a spokesman for PG&E, said the work was being done in “an abundance of caution” to minimize materials that might get sucked into the river if the land around the towers is eroded by the powerful flows.”

  72. This is scary, folks. The std spillway is eroding badly, but if they don’t use it, they will wreck the aux (emergency) spillway. They are juggling right now — hoping to balance damage so that neither one becomes catastrophic. If big rains come next week, it will be a losing battle. It is still early in the melt season and they have a monstrous snowpack upstream. Why the frig didn’t they draw down the lake level all through last month — it isn’t like the huge snowpack was a secret……

    • Believe it or not one thing that was a key for me in the briefing is how they changed the nomenclature from “emergency spillway” to “Auxiliary spillway”. When they start getting PC with their descriptions like that I tend to become suspicious.

    • Not only that, but the forecast for my area is now showing the next rain moving in on Wednesday instead of Thursday. The last several storms all came in almost a day ahead of the forecast as the winds have been steady in the mid 30+ mph range. That takes one day away from what they had been planning as stated in the most recent DWR video.
      Here is the cloud movement offshore, note the second storm to the west which has moved rapidly closer to the closer flow over the last 50 hours. I think that it will likely follow in right behind the closer storm. Meaning that the DWR estimate of less rain may be wrong . …https://earth.nullschool.net/#current/wind/surface/level/overlay=total_cloud_water/orthographic=-127.00,39.76,819

    • Um, I should clarify that, inasmuch that water storage became to great of a consideration rather than flood mitigation…. Which the Wivenhoe dam was originally designed to do…. The city of Brisbane is on a floodplain the Wivenhoe was built to mitigate floods, first and foremost and water storage secondary, but as a result of an extended drought, water storage became a priority and drought mitigation secondary, when weather patterns returned to a more normal state, in 2011, massive flooding resulted.
      Months of snow melt are still expected with this Oroville dam catchment…. They are essentially stuffed if rain piles upon snow melt.

  73. The level now seems to have stabilized (for the moment) at 902.6 feet, i e about 19 inches or just less than 0.5 meters above the emergency spillway level.
    It will probably soon start going down. Until the next rain comes in on Wednesday.

  74. About REBAR; look to the photos of the basement of San Francisco’s ‘leaning tower’ showing rusting rebar popping the concrete away. I lived in the tallest residence in Charleston, SC, built of reinforced concrete and repaired at vast expense by the Board of Owners – due to corroding rebar.
    Rust is lower density than the base steel alloy, meaning that it expands and cracks the concrete with internal pressure to which reinforced concrete structures are not robust. The cracks admit more water that accelerates the corrosion

  75. This guy deserves a medal. Pouring concrete from a truck boom onto a boulder field on the emergency spillway floor right next to the main spillway. Slip and fall between these boulders into the concrete and that could be it.
    You can see the cement boom truck above him on the road next the main spillway here. Top right corner.
    I don’t think they would want any erosion right here hence the need for a concreted boulder field.

  76. Water over the emergency spillway (weir) has now stabilized @ ~1.5 ft. Great opportunity for the engineers. My wild ass guess (WAG) is the overflow may be in the neighborhood of 8,000 – 9,000 cfs.
    As soon as the level drops to the top of the weir, then inspect the flow channel. Then, if that channel is reasonable/acceptable, shut down the primary spillway and inspect that. Keep the primary closed and allow another foot or so (2-3 ft) height flow over the emergency spillway for some period of time. Then inspect again. Rinse and repeat.
    Concept is to let the flowing waters scour/clean as required and then modifications/repairs can be targeted for just such a future occurrence.
    Next would be a little book keeping on data entries. Stop with inflow claims of cfs to a single digit. Impossible to do. Round out to the nearest 5k or so.
    There may be a silver lining in all of this.

    • EPA can do better than that with a backhoe and an old mine shaft. Call it art, color the water, AND get government funding!

    • harkin1,
      Thank you for the link. I certainly did not mean any negative connotations to your posting. It was just the first thought in my mind.
      That said, I stand by my comment!

      • No offense taken and I agree with your satire.
        I just wish they had better shots of the whole emergency spillway. This is really interesting.

  77. It is my understanding the US Army Corps of Engineers has never had a dam failure because “the dam was built too small”. Does anyone have evidence to the contrary? I ran a Marina in a Corp controlled reservoir in Colorado for 30 years.

    • I do not know about the anti static but they would close the roadway opposite the spillway at high flows in the past because the spray would get so thick that cars would stop running from too much water in the air.

    • This was in the Redding newspaper. I hope the PG&E workers got hazard pay –
      On Saturday, helicopters zoomed by, sometimes with a PG&E worker dangling from a rope. At one point, one of the men was deposited onto the metal structure where another member of his crew was already high above the terrain.
      Denny Boyles, a spokesman for PG&E, explained that the power lines crossing the rivers had been removed beneath the dam to “minimize material that could go into the river if there was damage.” The towers could not be removed in time for the water releases.

  78. Emergency evacuation order. Emergency spillway being undermined by erosion. They are upping spillway volume to 100,000 cfs to lower lake level. In a word, this is a diasaster like I predicted. They have no good options now. Either allow the emergency spillway to be undermined by the overflow or destroy the spillway itself by allowing huge volumes of water through it. If the next weather system dumps lots of rain on the area, a collapse of the dam is a distinct possibility.

  79. Something going on folks – my phone is lighting up that emergency spillway may “fail”!!….Oroville may be evac’d etc.
    This is not official – I’m trying to find something – Hope this is false alarm.

  80. From http://www.sacbee.com/news/state/california/water-and-drought/article132332499.html
    Butte County sheriff: “This in NOT A Drill.”
    5 p.m.
    The Butte County Sheriff’ Office released the following statement on Facebook:
    This is an evacuation order.
    Immediate evacuation from the low levels of Oroville and areas downstream is ordered.
    A hazardous situation is developing with the Oroville Dam auxiliary spillway. Operation of the auxiliary spillway has lead to severe erosion that could lead to a failure of the structure. Failure of the auxiliary spillway structure will result in an uncontrolled release of flood waters from Lake Oroville. In response to this developing situation, DWR is increasing water releases to 100,000 cubic feet per second.
    Immediate evacuation from the low levels of Oroville and areas downstream is ordered.
    This in NOT A Drill. This in NOT A Drill. This in NOT A Drill.
    Chris Orrock, a spokesman for the Department of Water Resources, told The Bee the failure happened as the bottom of the emergency spillway began to erode.
    “It happened quickly,” he said.
    Sutter County also put out an alert on Facebook:
    We have received information about the potential for increased flows in the Feather River of as much as 100,000 cubic feet per second. We are gathering as much information as possible and will be providing additional information as soon as it is verified.
    Officials warn of “imminent failure” at Oroville Dam’s emergency spillway
    4:45 p.m.
    Officials are warning those living downstream of Lake Oroville’s dam to evacuate because of a risk that the dam’s emergency spillway could collapse.
    “They have what they expect to be an imminent failure of the axillary [sic] spillway,” said Mike Smith, a spokesman for the California Department of Forestry and Fire Protection. “What they’re expecting is as much as 30 vertical feet of the top of the spillway could fail and could fail within one to two hours. We don’t know how much water that means, but we do know that’s potentially 30 feet of depth of Lake Oroville.”
    The Department of Water Resources, which operates the dam, said in a 4:42 p.m. Twitter post that the emergency spillway could fail within the next hour.
    “Oroville residents evacuate northward,” the Tweet said.

      • This is an extremely large lake. A thirty foot collapse would be catastrophic not only for immediate areas but also Marysville and Yuba City. The Sacramento River is also at or near flood stage so the extra water would also pose a significant risk to Woodland, Sacramento and possibly Davis — depending on the exact topography. Take Care! Listen Up!

    • Interesting Sherrif decides that the absence of models about what will happen if the emergency spillway goes, is a reason for him to evacuate

  81. Official from Sheriff’s office at press conference said increased flow at primary spillway has eased flow over emergency spillway significantly and it would actually stop sometime tonight.
    He also said there was a problem section on the emergency spillway that needs to be addressed and they planned to bring rocks/concrete in to plug some sort of gap when the flow over the emergency spillway ceases.
    I haven’t heard anyone address the new rain scheduled to hit later this week.

  82. The massive outflow now going down what’s left of the primary spillway seems to be going further and further towards the dam shoulder. There is also a massive wall above this section that looks to be something other than solid rock.
    I wonder if that wall will collapse and whether it could have any effect on dam integrity…..

    • Look how much of the mountainside has been blasted out to the right of the spillway. That shows what will happen, if the emergency weir fails times 100.

  83. Here’s the problem point, I think:
    To the right is the emergency spillway (then main spillway, then main part of dam). In the upper left is a parking lot that not only is flooded, but it’s draining down the hillside on the lower left. I assume that is a design flaw of incomprehensible proportions. In the center of the photo the water flowing at the edge of the emergency spillway is likely the concern – there is erosion around the end of the spillway, something that can increase quickly, increasing erosion as it does. People were talking about a failure within an hour, where failure might mean losing some 30 feet of lake level.
    They’ve cranked up the outflow of the main spillway a lot, the lake is lowering, the erosion is slower than they expected, so there’s a chance that disaster will be averted.
    Nothing is definite. If you live there, get out of there….

  84. Ric, I believe you made a good call on this.
    As far as evacuation goes, better safe than sorry with a potential of flooding while the town sleeps.

  85. American engineers are good in cleaning up the mesh.
    Dutch engineers are good in preventing the mesh.
    It’s a way of living.
    That’s why our dikes are designed tot withstand a once in 10000 years extreme whether event.
    That’s why we pray:
    “Lieve Heer geef ons ons dagelijks brood en af en toe natte voeten.”
    “Dear Lord give us our daily bread and once in a while wet feet.”
    just to remind us to build better dikes.
    My thoughts are with those living beneath the dam.

  86. Just an observation that the technical level of the reporting on the incident has been grade school level, leaving most people with the notion the dam will collapse. I have seen only one decent analysis in a link posted by Wim.
    All sorts of video of the emergency spillway obviously NOT collapsing or being undermined at lake level. Then zoom to some undisclosed location where a completely different structure, a concrete retaining wall, has an obvious and dangerous breach and they are dumping riprap in.
    In Wim’s link there is bewildered discussion of some location far below the dam. Maybe this is a detention basin intended to buffer emergency spillway release? Personally losing interest until someone who actually knows what they are talking about explains what is going on.

  87. Can someone show me where my reasoning is wrong here?
    The water over the ‘Auxiliary’ Spillway dropped because
    the water level dopped below 900 feet.
    However they cannot stop the damaged spillway to fix it
    because water is till flowing in large amounts into the lake from
    upstream , which will soon cause the ‘Auxillary’ spillway to start up again
    which would make any attempt to work below it dangerous/impossible.
    So they need to keep the damaged spillway running.
    But on Wednesday a new front, carrying at least as much a load as the one
    that started all this, is going to send huge amounts of water into the lake
    How I am seeing it is if they keep the damaged spillway going, that may/will
    saturate and erode the area in front of the Dam – likely causing the dam to fail.
    Alternately they can close it and leave it closed, let all the water go over the
    Auxiliary’ spillway, which will collapse and cause severe flooding downstream,
    but not catastrophic flooding as it would be if the dam went.
    The other worry is that graphs show multiple dams at, near or over rated capacity
    all feeding into the same downstream area – that is Sacramento and surrounds.
    I am assuming they will (assuming their spillways work), dump all the water they
    can which will add to the flooding downstream but save the Dams, and, again, a far
    greater catastrophe.
    If I lived anywhere from there to LA I would take a hike into the hills or a
    late booked sea cruise :\
    Thanks for any response – Janice, you are nice – thoughts? 🙂

    • Aidan, Your assessment about the damaged emergency spillway is correct. They are forced to use the primary at all costs to avoid using the secondary as it was the one that was rapidly undermining. Moreover, the primary spillway will have to be in continuous operation for the next few MONTHS as the lake would otherwise overflow via the emergency “spillway” which I think we can see is a misnomer. (at 901′ elv). Most of the lakes volume comes in March. And yes, inflow could exceed outflow and end up filling Lake Oroville again, especially if the primary becomes non-functional due to even further erosion. Furthermore, sediment into the pool below the turbines could render their output useless – another 12,000 cfm gone. As for the dam itself, we disagree. I don’t think it is in any jeopardy due to saturation – it’s capped and built to address that. Bob

  88. “the potential for increased flows in the Feather River of as much as 100,000 cubic feet per second.”
    The real potential is for much of the 5 cubic kilometres of water in the lake to suddenly go down the Feather River and surroundings, in about half an hour. They are very lucky that the inflow to the lake has reduced a lot. In the meantime they should keep the spillway flowing as fast as possible in case there’s a storm. And when they rebuild the spillway, put lots of welded steel mesh in the concrete, and about 5 times as much concrete, on proper foundations.

    • In Feb 1986, the peak Oroville inflow was 266,449 cubic feet per second. Imagine that repeating itself in the near future…. like next week.

  89. Anybody know how far down the primary spillway can draw? Can it draw to below 850′? 830′? Thanks a million.

  90. Oh, and also… I heard they can spill to 150,000 cfm… is that true? They’re spilling at 100k cfm now. (Obviously I’m researching their draw-down ability).

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