Very interesting picture and analysis of the visible cracks and the apparent attempt they are making to assess the condition under the spillway. Thank you!
Cracks on the surface, and an “interesting” pattern to the cracks. Lets hope there not voids in the substrate, but the pattern to the cracks certainly raises that possibility.
I wonder if those same cracks were there 2 months ago, and if they have grown since then? Likewise, I wonder if soundings have ever been done before. If so, how do they compare with NOW?
Let’s hope the analysis they are doing this time is correct. So far they have not inspired much confidence.
We already know the main spillway must be used for several months in a row during this year’s spring melt. If their current analysis shows the potential for further failure of the main spillway this spring, then they should be making contingency plans NOW.
If the main spillway reaches the point where it can no longer be used, it certainly seems possible that the “emergency” spillway could handle the whole load either.
So, in a worst case scenario, what are the other options?
I have no direct knowledge of these, but apparently there are two fingers of the lake with some sort of low dam that holds back water when the lake is high. These dams are not ever expected to actually let water out.
Could either of those small dams be intentionally breached instead of using the emergency spillway? There would certainly be downstream damage if they were, but the damage might be less than if the emergency spillway were to fail.
MARCH 3RD
The flood control spillway flows remain at 0 cubic feet per second (cfs). Inflows are approximately
15,000 to 20,000 cfs which has resulted in the lake rising from 845.6 feet to 848.3 feet elevation in
the last 24 hours. Flows to meet fishery requirements are being met by releases through the
Thermalito Diversion Dam and Thermalito Afterbay River Outlet. The total flow to the Feather
River remains at 2500 cfs.
Contractors continue to remove sediment and debris below the spillway. This operation will
continue 24 hours per day. Approximately 168,000 cubic yards of material have been removed
from the debris pile to date.
To prepare Hyatt Powerplant for operation, reconfiguration of the powerlines connecting the plant
to the grid was completed. Work continues on the area below the emergency spillway, access
roads, and various eroded areas created by emergency spillway runoff. Rock benches and check
dams are being constructed to slow water and reduce erosion should the emergency spillway be
required for use again.
For information on lake conditions; including lake levels, inflows, and outflows you can visit the
following website. http://cdec.water.ca.gov/cdecapp/resapp/resDetailOrig.action?resid=ORO
For more information on the Oroville Spillway Incident visit the
I have no direct knowledge of these, but apparently there are two fingers of the lake with some sort of low dam that holds back water when the lake is high. These dams are not ever expected to actually let water out.
Could either of those small dams be intentionally breached instead of using the emergency spillway? There would certainly be downstream damage if they were, but the damage might be less than if the emergency spillway were to fail.
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Intentional mini dam breaching: I believe you may be referring to Miner's Ranch Reservoir. There are two parts of this reservoir that have an NW dam (at Oroville lake) and a SE dam that completes the basin for Miner's Ranch Reservoir.
Any intentional breaching of these two reservoir dams, to prevent any further overtopping of the Oroville spillways, would lead to a deep erosion cascade heading towards -for example- North Huncut Creek, and the town of Huncut - IF the initial lake water elevation were high enough at the time of the breachings (above 890ft).
Putting aside the destruction of all of the Miners Ranch Reservoir, the homes, farms, businesses, etc. along the way in this erosion flood, the Oroville dam would force flood waters into this new "mess".
It would be trading one big problem (current challenges at the dam) for a brand new big problem.
Simple answer: The potential damage and flooding would be significant. As to which option results in the best of the worst, that is an answer that emergency contingency planners would have to answer.
RE Cracks: We've been discussing the "cracks" in prior posts. Yes cracks have been present for years prior. As we don't have any official failure analysis information, we don't know the extent of other contributing conditions (voids in the substrate, etc).
Now that the emergency has focused funding and manpower to the issues at hand, we can only hope that Nature will not overwhelm the current dam shortcomings (and temporary fixes).