[tevake]

"Just to be clear, the dam is not in danger and certainly supports a complete fill. If you mean by "support a complete fill" that the regulation of the water level is faulty, then you may have a point. However, the main spillway has worked perfectly for 50 years, often in years with complete fills and then some. This time, there was a break in the spillway bed (which to my knowledge has not been explained) that caused the flow to be reduced to the point where the lake level rose to breach the emergency spillway brim--something that has never happened. Projections of the ability of the emergency spillway to handle the overflow were theoretical and have proved to be in error. That's why the situation is as it is, today.[/QUOTE]

I'm just not sure how you can so positive about that, Osiblue, when the officials onsite have determined that a large scale evacuation is called for.
The compromised area in the emergency spillway as well as the large whole in the primary spillway, both may weaken the dam itself, or the critical surrounding terrain.

On Kauai we had a catastrophic earthen dam failure. When the intended spillway was partially filled in by the owner of the property was doing filling and grading in the area.
On a particularly persistent period of rain the water flowed over the dam itself causing erosion on the lower part of the dam, leading to a total failure and colapse of the dam.
With considerable loss of life down stream.

This was a much smaller dam and probably not exactly the same set up as the one in Ca.
But in my mind any time there are serious compromises in the body of an earthen dam,
The situation is serious and possibly catistrophic.

I certainly hope things with the dam go well, and the folks now having an evacucation, are soon safely back in their homes.

Cheers Richard