Lake Oroville nearing spillway level – watch using a new tool

After heavy winter storms, the water level stands just two feet below the new spillway gates – will it work?

When the #CampFire occurred, one of the very best tools out there on the web for tracking progress of the fire came from Peter Hansen, at Chico State University. Now he has a new interactive tool he has shared with me for use in monitoring the level of Lake Oroville as it fills and approaches the top.

Click image for the interactive tool

You can click the image above to open the interactive tool in a new browser tab.

California’s Department of Water resources provides tabular data, but no comparative visualizations. This interactive tool shows the the five most important variables that most people are interested in monitoring:

With a “full at the top” elevation of 900 feet, the interactive graph also displays the two most important benchmarks:

Right now, as of noon PST today, the lake level is at 810.84 feet, just 2.7 feet from the spillway gates, and rising 2-3 feet daily. At that rate, it will only be less than a day before the new billion-dollar spillway can be used/tested. DWR says there is an 813.6 foot threshold for use, and that is indicated by the orange line in the graph above.

Construction crews work Thursday Feb 22nd near the Oroville Dam spillway in Oroville. The state Department of Water Resources does not expect to use the spillway anytime soon, but says it is preparing to have the new structure cleared if Lake Oroville reaches 780 feet elevation. (Matt Bates — Enterprise Record)

It will be another couple of weeks before the water level makes its way all the way to the top, where the emergency spillway will be used if that happens. Of course, DWR may increase releases, so that may not happen.

Photo showing the elevations and placements of the gates and emergency spillway. h/t to Twitter via Rob Carlmark‏ @rcarlmark

Back in early February, DWR said they don’t plan to use the spillway soon, but then later changed their story to say they were making preparations to do so if the water level exceeded 780 feet elevation. That’s already happened.

All eyes are on DWR. Will they, or won’t they?

Already, there are concerns:

135 thoughts on “Lake Oroville nearing spillway level – watch using a new tool

  1. So why aren’t they using all that water to create carbon-free, renewable energy?

      • Yes, of course. 819 MW (6) hydro generators with the ability to be utilized as a pumped hydro storage in lower water when it isn’t spilling, using 519 MW of electricity on 3 of the 6 pump/generators to pump water back uphill into the dam when there is a surplus of electricity. I would assume they are generating the full 819 Mw as we speak.

        • They are not operating at full capacity at the moment because the management plan calls for maintaining somewhere about 840′. The flow through the power plant has been increased since the level reached ~800′, currently around 5000 cfs. So far the precipitation for the season has exceeded last years by ~15%.
          A good plot of the levels can be found at:

      • So instead of wind turbines or solar farms, why not build an additional hydro-power plant or two?

        • Most of this water will be held and run through the power plant over time. According to the new operating plan, if upstream conditions are wet, DNR will let the water build up to elevation 838. The water level would be drawn down in time from that through the power plant. There will be no need to use the recently constructed spillway. If upstream conditions are dry the bottom of the reserved flood storage will be higher.

          • Chris, what if the dam is full (like now), and further heavy upstream rain creates an inflow rate that exceeds the outflow thru the power plant? My logic says that they will have no alternative but to spill the excess water down the spillway.
            This exact situation has occured in two major dams in Australia recently. In both cases the very high spill rate needed to protect the over-full dam during a major rain event caused heavy flood damage ($ hundreds of millions) to residential and commercial property downstream. I will watch this dam with interest!

        • caída del río (??) as the Spanish would have claimed. Oroville a few-5 miles below the dam the Feather River meets the valley, where ‘fall’ needed in Hydro Electric generation is nearly too little. Would have been cheaper to invest in 1960 in more hydro capacity, but the Need for Southern California water-swimming pools vetoed the electric generation mode of logic.

      • And, 2 critical dams were part of the overall Water Project. A governor in the 70’s cancelled these 2 dams on the Yuba River. Now, the outflow of Oroville may not exceed a ?? total volume. These 2 dams would have been empty except during outrageous storms. The Yuba drains into the Feather at Marysville CA. Maximum engineered out flow Oroville would flood Marysville without the 2 cancelled dams.

        • The operating plans for the Oroville Dam have been revised to accommodate the lack of those two dams. With wet soil conditions upstream they will be reserving 920 million acre feet for flood control, an elevation of 838. They will maintain a smaller flood pool in dryer conditions. They have considered the flood levels downstream in the allowed rates of discharge to determine the storage they need.

    • It boils at ambient temperature because of a pressure drop, not by heating. School science classes used to create all three phases under an evacuated bell jar. The water would boil and ice would form from cooling caused by rapid evaporation. Now I guess they teach global warming science and тоталiтагуаи сivics.

        • We used to joke that you could hear the Soviet subs before they left port. OK, maybe it wasn’t a joke.

          On the other hand, Soviet subs may, or may not, have been pretty good at sneaking into Swedish waters. link

          • There was a big stink back when Reagan was president. The claim was that someone had sold the Soviet’s state of the art machining tools that they could use to make better propellers that were less likely to cavitate.

          • MarkW March 4, 2019 at 4:57 pm

            There was a big stink back when Reagan was president …

            Holy Moses! I didn’t remember that. link That explains a whole bunch.

      • Fire pumper engines are also subject to cavitation and damage should pressures and flow rates not be within design specs, hence always closely monitored.

    • The problem is when the inflow exceeds what the power plant and spillway can handle. If you don’t start using the spillway until the threshold of the emergency spillway has been reached, you run the risk of having to use the emergency spillway.

      Right now the managers are bugging all the weather guys in the area trying to get a best guess of how much water is going to fall in the drainage area over the next few weeks. (Not to mention trying to guess now much snow there is and how fast it will melt.)

    • FYI … CA reservoirs are usually at their highest levels in June-July after MOST of the snowmelt has found its way into the reservoirs. For our reservoirs to be this FULL on Mar. 1 … with the Sierra snowpack >150% of ‘normal’ … suggests an urgent need for dumping our reservoirs. Oops! can’t do that … all the downstream facilities are at capacity. Gonna be a UUuuge flood plain across the Central Valley this year.

      In a related story, Jerry Brown was seen pacing – back and forth, back and forth – in his remote CA cabin muttering something about a … “never-ending CA drought”

    • It’s an earthen dam, so any flow over the top dam is fatal. The flood control spillway should be able to handle all flood situations, but if not, then there is the emergency spillway to left of the flood control spillway.

      The original flood control spillway failed in 2017 so the emergency spillway came into use; the water started immediately to undercut the emergency spillway, forcing evacuations below the dam. They were forced to use the failed flood control spillway which gouged a canyon over 150 feet deep under the spillway.

      The canyon was filled with roller compacted concrete anchored to the bedrock below. They actually, swept, vacuumed and washed all the way down to bedrock under the new spillway. They called it ‘dental work’ when removing all the debris.

      • Both spillways are seperated from the main dam by a ridge of rock. No matter how bad the spillways got, they couldn’t undercut the dam itself.

  2. Interesting that they actually got it complete so quickly since it was only 2 years ago. But it would be very sad it doesn’t perform.

  3. That concrete is less than 12 months old. So it’s still curing and is relatively week. The bigger obvious problem (as the diagram points out), is the side walls. The comment about cavitation along the inside gutter is especially worrying. Cavitation is well known to occur in large volumes of rapidly moving water – as especially at locations where there will be pressure differentials (ie – in the right angle of that gutter).

    • 90% of full strength at 28 days … and should have a large safety margin .
      Expect extra margin due to political concerns .

      • “Expect extra margin due to political concerns…”

        Let’s hope so. But remember this spillway was likely designed by, and construction was supervised by the Army Corps of Engineers. No disrespect intended toward the USACE, as I worked with them for years and know from experience that they’re great guys. But in most cases I discovered that comparing them to real engineers was like comparing public defenders to Johnny Cochran.

      • @sweet

        I thot the time for a good cure depended upon how thick the concrete is poured, maybe the volume.
        Didn’t the Boulder concrete have cooling piping?
        Gums asks….

      • Data I have seen shows that it reaches a plateau after about 90 days. Of course it depends on the type of concrete.

    • Concrete is designed around the strength it achieves after 28 days of cure. It is plenty strong. The depth of water in this structure will only ever get a few feet deep . The former structure did not fail because of the water inside the structure: it failed because the drainage system below got plugged and the forces of the water underneath displaced the concrete upwards.

      Cavitation did not happen with the old structure after multiple uses. There is no reason to expect that it will be a problem with the new structure.

      • underdrain problem … as I said when it was failing. Although, I don’t really believe in the clog explanation … it appeared to have limited abilities to begin with.

        Current weep at joints (now, when dry) is interesting.

        I don’t see an adequate underdrain in this design either.

        (what is the pipe on the outside of the walls?)

        (will they install a 36″ drain at the base of the walls before backfilling?)

    • They spent a billion dollars for a spillway. The Hoover dam cost less.

      The Hoover Dam was finished in five years — two years ahead of schedule — and cost a $49 million, which is worth under $750 million today. link

      Of course, today worker safety rules and environmental impact studies would kill the project by making it vastly more expensive.

      I’m all for telling the bureaucrats that they can have just 1/10 the regulations they now have. We need a rule (yeah I know) that makes justifying and creating regulations so burdensome that almost no new regulations happen. Oh yeah, another thing. The bureaucrats shouldn’t be able to burden us by referring to external standards like UL. If they do, the content of the external standard should count against the 10% limit.

      • They spent a billion dollars for a spillway. The Hoover dam cost less.

        The Hoover Dam was finished in five years — two years ahead of schedule — and cost a $49 million, which is worth under $750 million today.
        Of course, today worker safety rules and environmental impact studies would kill the project by making it vastly more expensive.

        96 workers died constructing the Hoover dam, none died in building the Spillway, perhaps those rules have a purpose?

  4. Juan Brown of Blancolirio youtube fame has covered the disaster and rebuilding of the spillway extensively. There’s plenty of rebar in there now, and a solid base down to good bedrock. The joints might need some work, based on the picture in the post. I suspect that they will operate all the turbines at full flow before letting much water go down the spillway. Although, this is a nice opportunity to test it.


      Consistent inflows between 20,000 and 30,000 cfs … they are operating the hydro power outflows at 5500 to 8,000 cfs (meaning just a couple of the 6 generators operating)… they can outfow as much as appx 18,000 cfs if needed.

      They are allowing the reservoir to fill at appx 2.74 feet per day – now at 829.14.

      DWR’s target was to stay under 835 for February, and 848 for March.

      They are above the 813 foot elevation of the spillway gates, so can release water when/as needed.

      At this time of the season they are transitioning to the dams primary purpose – which is to store water for the summer, and as such they are allowing levels to rise. Once they get to 848 they will likely start releasing water … first thru the hydro power plant (up to 17,900 cfs outflow) and then to the spillway, which can accomodate 100,000 cfs – for a combined total outflow capacity of appx 118,000 cfs.

      During the failure several years ago, the hydro plant was largely out of service for repairs, and then as debris filled the river it caused levels to rise upstream forcing closure of the hydro plant to protect it.

      Just 4 days in the last decade have exceeded 100,000 cfs; 101,000, 108,000, 130,000 and 155,000 cfs, all in the couple day period of early 2017.

      Theoretically, with the main spillway and hydro at full outflow, and a starting elevation of appx 849 feet, the dam could sustain the 150,000 cfs rate (which has occurred just one day since 2000) for appx 18 days +/- before reaching the emergency spillway elevation of 901 feet.

  5. Certainly much, much better than what was there before, and will work great for the next 100 years as it cures. I doubt there will be any issues, if it was engineered to modern day standards. Maybe it isn’t fully finished yet from the looks of things… I don’t know the construction schedule or details of how it was constructed. It appears to be cast in place concrete on bedrock, so as long as they put enough rebar in it, the cement should be cured enough in a year now to withstand a very high flow.

    Sure is nice to see the California reservoirs filling to Full Supply levels. Would also be nice to see the Colorado River watershed fill to max and refill all the large dams to full supply, and then the South West states, California and Mexico can weather the next drought that is guaranteed to happen forever. Catch the surplus water when you can! Water is money and life in the desert states, and especially in California.

    • After removing the old spillway, they chiseled down to bedrock (about 100 feet in one spot), removed about a foot to make sure they were on the good stuff, then used shop vacs and water jets to clean the bedrock. The first layer was a special concrete made to adhere to the rock. Then they added layers or roller-compacted concrete up to about three feet below grade. The top layer is high-quality concrete made to resist water flow and cavitation, bolted down about 20 feet, lots of rebar in two layers, better drainage system, etc. They also rebuilt the emergency spillway and added a wall to prevent erosion from reaching the walls of the emergency spillway. Nice what a lot of money can buy.

    • I’ve been wondering about the Colorado watershed too. My Boulder brother has said that many of these storms hitting the Pacific coast have been bringing lots of weather towards him. Any links to Rockies snowpack data?

    • 50-50. They recycled the old diffusers by shaving off 18″ old concrete and saved what rebar they could and then drilled/anchored in new bolts to the old concrete and then a whack of new rebar which then had a thick new cap poured of 5000 PSI concrete which also of course is water/wear resistant. The video below at about the 22 minute mark details all this very well. Very Skookum…this spillway ain’t going anywhere for a very long time.

  6. Here is a link to the new Operating Plan.

  7. Chris, what if the dam is full (like now), and further heavy upstream rain creates an inflow rate that exceeds the outflow thru the power plant? My logic says that they will have no alternative but to spill the excess water down the spillway.
    This exact situation has occured in two major dams in Australia recently. In both cases the very high spill rate needed to protect the over-full dam during a major rain event caused heavy flood damage ($ hundreds of millions) to residential and commercial property downstream. I will watch this dam with interest!

    • First, the reservoir is not full. What I would call full is when it hits the conservation pool level. I’ll call that 838 feet based on the new operating plan. They determined that elevation according to the volume they need to retain the design flood: that is the volume they will have empty above 838 and below the top of the emergency spillway. When elevation 838 is reached, the effort will be to match the outflow of the spillway to the inflows to hold the elevation at 838. The spillway can put out 150,000 cfs (cubic feet per second) but they will limit it to 100,000 cfs because of downstream flooding conditions. So they will let out the minimum of the rate of inflow or 100,000 cfs. If the inflows are higher than 100,000 cfs the excess volume will accumulate in the reservoir above 838: that is what the flood storage is for. When inflows eventually decline below 100,000 cfs they will continue discharging at 100,000 cfs until the water gets down to 838, then they will match inflow and outflow.

      They have adopted a more complicated plan wherein they can adjust the Conservation pool to as high as 870 depending on upstream conditions, but that is the basics of flood control. In the summer they will draw down below 838 for power production and irrigation promises.

      • thanks, Chris. Just for comparison, here is a link to the Townsville (Aust) Ross River dam levels, showing a recent extreme weather pattern that dumped huge rainfall on the catchment:
        The dam went from approx 65% full to almost 250% full in a couple of days (100% being the nominal ”full’ level for drinking water, the rest of te capacity (total of 233,000 ML or 190,000 acre-feet) being for flood mitigation purposes. Then they opened the gates at 2 ML/sec / 1.6 acre-feet/sec), which exacerbated the flooding of the downtown area. Could they have done a better job managing this dam? cheers,

  8. People worrying about the new spillway are doing so based on low information, bad information, or misinformation, or a combination thereof. If one has any interest at all on the subject I highly suggest watching Juan Browne’s superb coverage of the project from start to finish on his YouTube channel (blancolirio).

    The spillway has been ready for operation since November 2018, but with lake levels as low as they were there was no chance of it being used for several months at the very least. The wall joints and slab joints are designed with a relief so water flows right past with no disturbance/cavitation (referred to as a “high-velocity water joint”). All of these things are clearly detailed in his videos.

    Go to 11:05 in this second video to see joints:

    • If anything, they went beyond what was needed. You do that when you are replacing a failed structure.

      • It’s about time that they recognized the danger potential. There have been 3 times where flooding rains struck that area. The first time was in the winter of 1964/65. That was the winter which filled the empty dam years before it was supposed to fill. So a catastrophic flood was averted and reduced to a disastrous flood for California, Oregon , and Washington.

        The next close call was in the winter of 1996/97. An incredible 30+ days of rain for Northern California and Southern Oregon. The last close call was the winter of 2016/17. Thankfully, the rains came to a halt. Those are the last 3 major flood winters for the West Coast. Note the proximity to the solar minimum in each case.

        • I should have added that the 3 winters mentioned above were all winters in which water came close to going over the spillways at Oroville.

        • Notice that in each of those events a rather thin film of 12 inches of concrete was sufficient to deal with the forces of the flowing water. What caused the former structure to fail was not the flowing water, it was the failure of the drainage system, which was only coincidentally related to the overflow. Because conditions were generally wet, water pressure built up under the structure at the same time it was needed.

          • Also the original structure didn’t go down all the way to sound bedrock, something they have done with the current rebuild.

  9. That chart is pretty neat. Some of the other charts on the website are pretty slick as well. It looks like the website provides to subscribers tools for charting data. I notice, that on the Oroville Dam chart, there is an option to bring up the next 3 weeks of data. What does that mean?

  10. Forget about the rain, it’s the snow pack we need to worry about. March 1 snow measurements up around Tahoe showed the greatest water content ever recorded since they had been taking measurements. As we progress through March, the storms will begin to get warmer. Some of California’s greatest floods have been around Easter time which comes after the spring equinox. If we get a warm wet storm that melts a lot of snow pack in addition to the rain, then it’s “Katy, bar the door!” We’re in for a mess. I recall a year in the 1980s when we had a really bad flood. Levees broke and they were plucking people off of freeway overpasses by helicopter in Manteca, CA. The 150% is an average. It is 200% of normal at Truckee #2 SNOTEL station. The Truckee river into the Reno area is going to flood pretty badly. We really need to hope we have a cool spring or if it does warm up, that it stays dry. What we do NOT need is warm rain.

  11. “Forget about the rain, it’s the snow pack we need to worry about.”

    Actually, it’s a hard rain on a big snow pack that is the most dangerous thing to any mega flooding as history shows us everywhere at higher elevations and northerly locations in the late winter or spring. Hopefully, it isn’t a late warm rain on an unmelted snow pack, which is real mess because not only is it the local rain content, but also much of the accumulated snow content that melts all at once by the rain and is an instant flood. That is what caused the devastating floods in Alberta/Calgary back in mid to late June/2013 when warm spring rains fell on the higher elevation Rocky Mountains that were still all covered in deep snow from a real cold spring. Same as the 1948 May/June flooding across much of the Pacific North West and a lot of the western NA continent.

    • Earthling 2 has it exactly right. The same amount of rain can be safe or dangerous depending on its temperature and the air temperature at the point where it is falling. A warm late rain on an unmelted snowpack is the most dangerous because the warm rain melts the snowpack, which releases the combined water amount of both the rain AND the underlying snowpack at the same time. That kind of water pulse can overwhelm a reservoir.

      So a large rainfall in really cold air temperatures produces a large snowfall, and snowfall on the Oroville Reservoir watershed isn’t dangerous at the time it falls, or when it melts gradually during the summer.

  12. “The floor panels on Oroville Dam’s spillway appear shoddily jointed, & gutter-jointed at that. See how rainwater runs sideways into the joints? Not a smooth surface. When 100,000 cubic feet of water per second hits that floor, = cavitation?”

    “Cavitation” is a problem with hard materials e.g. steel. Under high pressure.

    The problem for concrete walls would be flushing, washing out.

    But that would be easily recognizable from the outside.

  13. The level rose 3 feet on the 4th March.
    It was inly 1.5 feet from the spillway.
    We are now halfway through the 5th, so I am guessing the water has reached the spillway.
    Sadly the linked pages to the monitor have not updated, can anyone say if the water is now flowing down the spillway? Is it automatic or does it get released down the spill way? The water will rise by around 3 feet per day, so what next?



    • According to the revised operating plan, water will get to elevation 838 or above,\ before the gates are opened. They will then try to make outflow match inflow limited to a flow of 100,000 cfs.

      • Yes If they matched outflow to inflow now they’d have an extra ~30,000 cfs in the Feather river, better to delay outflow increase until the natural river flow goes down then gradually bring it up. After all that’s what the dam is for, flood control.

  14. I note having just Bing mapped the reservoir that the image on Bing is still of the wreckage of the spillway. That was one seriously scary incident.

  15. If anything the whole re-do was way over engineered.
    As it should be I suppose.
    I followed all of the work and was impressed with the extreme measures taken to rebuild it all.
    Any suggestions of shoddy engineering or work or are absurd.

  16. Thanks for posting this. I looked on the website, and found this link to tutorials on how to produce your own charts: — I am no very artistically inclined, but I’m thinking about signing up for an account (it says registration is free), and see what I can create. The website also says something about a workbook being a available. The only negative is that the introductory tutorial shows how to create a chart of carbon-dioxide “pollution” by country. In the example it shows that Qatar is the biggest polluter, but their CO2 output is decreasing, while Trinidad and Tobago is increasing CO2 output. Well, who cares — those islands will be well below sea level in a few more years .

  17. Who needs sturdy construction when you have “official” pronouncements of permanent drought for the long term? Rename it the Jerry Brown Spillway.

  18. It appears that the spillway sill level only represents about 2/3 of the nominal capacity of the reservoir. That is, the current water level is recorded as 66% of capacity and 94% of average for this day of the year.
    The article makes it clear that the spillway is below the emergency spillway but implies it will get there in a few weeks. That seems very ‘optimistic’ as the capacity percentage has been rising slowly even with recent rains.
    When the original emergency spillway was in use and chewing itself up, the the capacity percentage was recorded above 100% at as much as 104%, IIRC.
    The URL below retrieves a pdf that is updated daily, usually before 2PM as of the midnight previous.
    You can see the ‘devastating’ drought that California is suffering in the depletion of its largest reservoirs.(sarc).

    • The percentage of capacity available at what level is irrelevant. What is relevant is the volume needed to retain the design flood. The operating plan reserved that volume as empty below the emergency spillway when the water is at elev 838.

      • You seem fixated on height which is irrelevant to the comment I made. If you want to talk about something else, go ahead.

        Capacity determines when overflow and the necessity of using the emergency spillway occurs. One third of the total volume or 50% of the current volume of water must be retained to reach the emergency spillway based on today’s volume.

        Have I misstated something?

        • @John Brisbin You’re correct. There is plenty of capacity available, particularly considering the hyatt power plant is only consuming a relatively small amount of the inflow at this time, 5000 cfs. At full flow, the plant consumes 16,950 cfs. I believe one of the 6 turbines is under repair, reducing the maximum by 2800-2850 cfs.

        • The modelling for the current operating strategy determined that 920 million acre feet of storage is needed to contain the design event under the planned discharge limits. If you have 1,840 million acre feet of storage available that is 50 per cent. If you have 2,760 million acre feet of storage available that is 33 percent. Per cent of reservoir volume that is available is a meaningless number, 920 million acre feet is what matters.

          I “fixate” on the elevation of 838 feet because at that elevation there is sufficient volume available (920 million acre feet) to ameliorate the design flood before the emergency spillway is over topped. It does not matter if there are 920 million acre feet below that, or 1,840 million acre feet. The volume that matters is 920 million acre feet available to deal with what is to come. Whether that is 33 percent of the volume or 50 percent of the volume of the reservoir is not relevant. 920 million acre feet available is the critical volume. It just so happens that the required volume to retain the design flood is available when the elevation of the water in the reservoir reaches 838 feet in the wettest conditions considered by the revised operations plan.

          I would have preferred that they would have reconsidered the design flood in light of the additional 60 years experience, but the design floods as determined in the original design are the ones that have been used in the analysis and are the best available at the moment. With the current stream flow routing models and discharge protocols it is determined that 920 million acre feet of storage is needed to ameliorate the design conditions. Whether that is 30, 50, or 90 percent of the volume of the reservoir does not matter. It happens that at or about a water surface elevation of 838 feet that 920 million acre feet of additional storage remains: it is that volume remaining that matters.

          • I can see that you have a problem with responding to what was said and instead would prefer to work your prepared talking points. I can see that you are well informed about enough ‘trees’ that an observation about the ‘forest’ is incomprehensible.

            Fine. I am not playing any more.

          • Perhaps you would like to explain what this means?
            “The article makes it clear that the spillway is below the emergency spillway but implies it will get there in a few weeks.”

  19. Lake Oroville dam live feed webcams. Note that some may be offline and ever since Kiewit took the night worklights down, it is best viewed during daylight. The best one, that looked up the main spillway from across the river is no longer active, nor is the one that looked at the emergency spillway:

    Lake Oroville SRA Spillway Top

    Lake Oroville SRA Visitor Center

    Lake Oroville SRA North Forebay

    There is also California DWR youtube that has lots of videos during construction:

    I watched DWR and Blancolirio construction updates on an almost daily basis and it was fascinating. Kiewit did a first class job and I don’t believe the Army Corps was involved (unless in a minor way). It was all DWR and Kiewit.

    What does $1.1 billion get?
    The concrete on the original spillway chute had an average thickness of 2 feet 8 inches.
    The new spillway chute is about three times as thick, an average of 7 feet 6 inches.
    The rebar on the original spillway was 4 million pounds.
    The rebar on the new spillway is three times heavier, at more than 12 million pounds.
    The main spillway has more than half a million cubic yards of concrete.
    Combined, the main and emergency spillways have more than 1.2 million cubic yards of concrete.

    • Not to mention that the old one had to be removed and then dug down to sound bedrock (something that was apparently not done when the first one was constructed. 600 workers on double shifts for a year or so not cheap either. Agree about Juan’s work on the Blancolirio channel!

  20. Oroville UPDATE Feb ’19 – When will the new Spillway be Used? Update in the Mighty Luscombe after heavy rains and snow in Feb. 2019.
    blancolirio Published on Mar 3, 2019

    • It will depend greatly on how the spring temps and storms unfold. The winter of 1996/97 showed what will happen when continuous warm rains impact the snow pack. In that fall/winter temps dropped early on. There were early snows in the Sierras which built up a decent snowpack by December. Then at the end of November a warmer storm system moved in, and it began to rain all day every day for the next 30+ days, maybe about 34 days in a row without let up.

      Towards the end of all that lakes were forming in the Sacramento Valley. The flood gates to the west of Sacramento had to be opened to let waters surge south out of the river and into the valley. It was around that time when the spillways at the Oroville dam had to be used for the first time. I think that the initial damage to the spillway occurred at that time.

      I was living in Marin County at the time. Every little rivulet of water had become a raging torrent. A tiny 6 inch deep stream in a drainage ditch close to the house I rented rose some 15 feet to overflow the drainage. That started cutting off access to nearby houses. The non stop rain at that point was becoming semi biblical. Millions of people were now affected by the rain.

      Then the strange happened. The last night of rain I was watching tv, and had gotten up to smoke a cigarette on the back porch as I had promised the landlord to not smoke in her house. The rain was light. As I stood there facing to the north I said a quiet prayer “Lord you are going to flood all of us, if the rains do not stop”. Just like that the rains came to an end. The clouds opened up in a large crack to the north of me, and there was comet Hale Bopp falling in the north northwest sky right in the middle of that crack in the clouds. I stood there in amazement wondering at the sequence of events. At the time I felt like an old time prophet.

  21. I see that it is still snowing in the Sierras which when it melts, a lot of it feeds into this reservoir..
    It looks to me that there is more snow than when it happened two years ago.
    I sure hope that what they have done will prevent what happened before…just hope that the snow melts slowly…I think that the level should be lower now…it’s still winter in the mountains.

  22. All eyes are on DWR. Will they, or won’t they?

    Already, there are concerns:

    From a self styled ‘Amateur cryptodamologis’ with a fixation on Oroville’s ‘green spot’ not a credible source.

    • Yeah, it’s now at 823′, the outflow has now been increased to 8,000 cfs. Inflow has been slowly dropping today.

    • So they might have rain until Tuesday, I am hoping that nothing happens like in Feb. 2017. I am just keeping track of what is happening… maybe lower the lake level gradually so what occurred in 2017 doesn’t happen again.
      During the spring melt.

  23. Anthony… you might want to update the graph at the top, or at least mention that the water is 11 feet above the sill at 10 pm pacific time – In some kind of an update.

  24. Looks like DWR are maintaining a river release of ~7,000 cfs and as the inflow is dropping fairly steadily they seem to have a good handle on things. They could significantly increase flow through the Hyatt powerplant but that would mean increasing the river flow, they’re still below the target capacity so unless there’s a huge storm forecast they might as well stay on the current plan.

    • River release has dropped and outflow is close to inflow now, converging on 848′ level, looks like it’s being well managed just by the Hyatt plant alone.

      836.82 2,635,392 7,829 10,901 5,119

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