Lake Oroville 100% Full; Emergency Spillway Use Hours Away?

February 11th, 2017 by Roy W. Spencer, Ph. D.

UPDATE: As of 9 a.m. PST, the water level has increased to 901.24 ft., and water is overflowing the 1,700 ft. long emergency spillway.

For the first time in the 50 year history of Oroville Dam, Lake Oroville has exceeded its design limit as of 3 a.m. PST this morning, reaching 900.1 ft. elevation.

The inflow rate into the reservoir continues to exceed the outflow rate, increasing the probability of the first-ever use of the emergency spillway. This would cause massive erosion of the hillside, which in this Google Earth image is to the left of the narrow concrete spillway (2015 imagery, reservoir 50% full):

I have made an estimate of when the emergency spillway might be breached based upon rates of inflow and outflow; the following chart suggests around 8 a.m. this morning:

Observed (blue) and model-estimated (orange) Lake Oroville water levels.

These (unofficial) model-projected levels in the above chart assume measured inflow into the reservoir continues its steady decrease, and the outflow remains the same as it has been since 8 p.m. last night, when engineers reduced the flow through the damaged concrete spillway to avoid damage to power line towers:

Even if flow through the concrete spillway is increased to full-flow, the topping of the emergency spillway would only be delayed by an hour or so (9 a.m.). Lake levels would not keep increasing afterward, as suggested in the above chart… the model estimates are just meant to suggest we are likely headed to a breach of the emergency spillway, which will then provide an additional outflow channel for the lake.

I have no idea whether engineers have any “tricks up their sleeve” to avoid the emergency water release. The electricity generating turbines have been shut down due to debris in the water. I suspect we will be seeing some rather dramatic (and very muddy) video later today.

(Oroville Mercury Register live news updates.)

(Follow the hourly updates of water flow and lake level.)

27 Responses to “Lake Oroville 100% Full; Emergency Spillway Use Hours Away?”

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  1. Jim Horne says:

    Well done. And yet news outlets have continued to quote DWR “experts” stating that they were confident they could avoid using the emergency spillway, even as the inflow continued to exceed the outflow by 50,000 cubic feet every second. [And they are just as confident that the untested, 50-year-old emergency spillway will work as designed. We will know in a few hours.]

    Perhaps you can clarify something. It has been said in news stories for many years that the dam came within one foot of overflowing in January 1997. Yet CDEC records show that the reservoir crested at 887.19 at 9 a.m. on January 3, 1997. This is 13 feet below 900 feet?

  2. Dave Hurley says:

    It seems that they just can’t get a handle on the situation, either that or they just aren’t forthcoming with all the information. I live in Idaho right next to the flood plain of the Boise River, and whats happening at Oroville doesn’t give me the greatest confidence that they will manage things much better here.

    Global warming is bringing spring run-off earlier in the year with each passing decade. They are going to have to modify their forecast models to allow for these warm & wet spring rains, and unlike the Feather River, which can handle high flows, the Boise River cannot, thus water management is crucial to preventing situations like we now have going on at Oroville.

    • Yes, I was a little surprised they were projecting early yesterday the emergency spillway wouldn’t be breached. Maybe wishful thinking?

      • Lokenbr says:

        I was shaking my head as well. As someone with background in hydrology, it was pretty obvious yesterday that it would get to this point.

    • john zimmerman says:

      “Global warming is bringing spring run-off earlier in the year with each passing decade.” = assumption

      • Jake says:

        John: There IS global warming, that much should be said if we are going to present the truth backed by facts. Having said that, how much humans are responsible, how trustworthy model projections of the future are and whether the consequences will be catastrophic (who knows, maybe beneficial?) can easily be debated.

        • Gordon Robertson says:

          Jake…”John: There IS global warming, that much should be said if we are going to present the truth backed by facts”.

          Sticking with real data and facts, there has been no significant global warming since 1998 according to sources like the IPCC and UAH.

          The record warming being bandied about by the likes of NOAA is based on highly manipulated and cherry picked data. Their own satellite temperature data, which UAH uses for their data sets, refutes the claims made by NOAA based on their surface station manipulations.

          • Jake says:

            Gordon, this is what is wrong with this issue, the fact that everyone wants to cherry pick. OK, you pick 1998 … I agree, you’re correct, no statistical warming. BUT, I pick from the start of the UAH temperature record … guess what, WARMING. Glaciers are melting, and the static state of temperature since 1998 is still above “normal”, whatever the hell we want to define that as. So, my “facts” beat your facts ……
            I believe that our current warming is GOOD, I think the the IPCC and the NOAA are agenda driven, which is BAD … but to be truthful, your comment isn’t much better ….. there are very few “scientists” who contribute here, and by that I mean, folks who want to leave bias on the table.

  3. David says:

    The rate of increase has been nearly linear for 12 hours, aided by the fact that they decreased the outflow as the inflow decline was beginning to slow. Simple math showed 900 was unavoidable. I didn’t realize 901 was the true value (also unavoidable at this point).

    So the volume over the emergency spillway will eventually rise to equal the inflow volume minus the spillway volume, maybe peaking around 40000 cfs? That’s going to cut quite a gouge.

    Where did you learn that the overflow height is 901ft., and not the 900 ft figure I see everywhere else?

    • Roy Spencer says:

      It’s repeated many places. Google:
      lake oroville emergency spillway 901 ft

    • MightyMoe says:

      The difference in elevation is probably the difference created by the newer elevation datum of NAVD88. The dam was constructed prior to the NAVD88 datum which adjusted elevations and no doubt used the earlier realization of NGVD29; in the dam area the adjustment was about a +1.5′. The historical elevation on NGVD29 datum would be lower by a small amount.

  4. boozedog says:

    Seeing additional data after 3AM here:

    02/11/2017 04:00 900.31 3542481 55034 94817 59430 34.76 13.4
    02/11/2017 05:00 900.55 3546278 55045 97652 59300 34.76 13.4
    02/11/2017 06:00 900.72 3548970 55110 96115 59430 34.76 13.4

  5. boozedog says:

    According to this tweet, emergency spillway is already being used.

  6. boozedog says:

    and … now that tweet’s been deleted. weird.

  7. ren says:

    The jet stream moves north over the California and in California the temperature rises.

  8. RAH says:

    It’s a disaster unfolding in slow motion right now like a train wreck one see’s coming but can’t do anything to stop it. Your not sure just how bad it going to be but you know that even in the best imaginable case it’s going to nasty. I just hope the dam survives.

  9. Roy Spencer says:

    Dramatic live helicopter coverage from KCRA-TV, water now flowing over the 1,700 ft-long emergency spillway wall.

    • RAH says:

      Those reporters sure are reassuring about relying on a spillway constructed in the 60’s and, if I understand correctly, never used before. Especially considering that with all the rain that spillway is probably going to have to be used for some days to come.

  10. Gordon Robertson says:

    I hope they have done something downstream to get people out of harms way.

    I read the story of the Dambuster’s raid when Allied bombers bombed and broke a major dam on a river in Germany. The carnage downstream was unbelievable.

  11. John says:

    Here is footage from earlier today showing the emergency spillway being used. This was being live streamed by different people at different angles for a while until the man with the clearest shot left and you could see it getting worse with your own eyes minute by minute. The man has appearently deleted the videos and his account is no longer on youtube. This was the latest footage of what is going on. I can tell you for sure there was water flowing under those powerlines. Evacuation maybe?

  12. Robbie says:

    I have a question. Does anyone have a guess as to how long the emergency spillway berm can hold up to the erosion that is being caused to it and also how high the berm is?

  13. David L. Hagen says:

    Erosion is a strong function of velocity and inversely with hardness.
    e.g. Glen Canyon Dam severe cavitation erosion of spillway. “The worst damage occurred in the left tunnel spillway – a hole 35-feet deep, 134-feet long and 50-feet wide was eroded at the elbow into the soft sandstone (Burgi, 1987). Extensive concrete repair work and installation of air slots was required to bring the spillways back into service and reduce the potential for future damage.”

    (I recall a high dam in South America once had several meters / hour erosion through concrete at the base of the spillway on first testing due to poor design. Can’t find the ref.)