re: Largest Dam in the Country at risk to fail EDIT- no immediate danger

This is one of the lakes they used for drought propaganda during their crisis

Any civil/environmental engineers on the OT?

How could this be corrected?

I am afraid it will flood

ell, I hope nothing happens to the dam. Would hate to see people loose everything. But really they need to make the people in charge pay the price for failing there safety.

The emergency spillway was rated for 250,000 cubic feet per second, yet it began to fail at only 12,600 cubic feet per second. Yeesh.

Apparently they believe they can get the water level 50 feet lower by the time they get more rain. That's crazy.

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It looks like the main spillway failed due to a sinkhole and they shut it off to inspect it. However as the water rose eventually it got so high that the auxiliary overflow was used, and because the auxiliary spillway wasnt armored, it scoured away the soil supporting it, endangering the structure itself...

So many questions, but mainly why wasn't the auxiliary spillway lined with concrete?

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Correct, I've been following this for a few days.

The "main" spillway which is concrete lined from the 60's was never used in operation until now and crews had growing concerns of soil breakouts, sinkholes, etc...

As the water levels continued to rise they had no choice but to release water through the main spillway to mitigate in the inflow, as this happened the soil obviously began to erode further and further creating the now massive size hole in the concrete structure. It's still able to gravity release water and help the dam but the entire integrity of the structure will need to be evaluated after this is over.

The "emergency" spillway as seen in tigertatortot's picture obviously seemed to be an after thought which was never lined with concrete around the base of the weir structure. Just days ago they had crews pumping concrete into the rip rap rocks at the base of the wall (top left of the picture) to help ease the energy of the water pounding away as it overcame the invert. To me this was just to ease the erosion and scouring of that hillside around the walls as the water basically overtook that entire area downstream.

Evaporation in sunlight and dry air removes a lot of water on that size surface area

The large cut near the face of the emergency spillway that has people worried

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Just don't see how that's possible. heard at one point the water level was dropping by 4" per hour. At that rate, they'd need over 6 days to get 50' down.

And, how are they releasing water when the spillway is closed for repairs?

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The main spillway is still being used at approximately 100k cubic feet per second, below its 150k capacity. You've got to remember that the surface area will shrink as the water level comes down, so lowering the level that last foot will take much less discharge than the first foot.