IOWs, the emergency spillway is doing exactly what it was designed to do.
I’ve built scores of them, on a much much smaller scale.
The overflow is contained when the main outlet cannot handle the load.
Uh, no. In this case the spillway has failed and had to be shut down else the dam erodes away. See Teton Dam failure.
The emergency spillway appears to be seriously damaged.
IOWs, the emergency spillway is doing exactly what it was designed to do.
The regular spill way is 750 feet of concrete where at the bottom there are barriers to shoot the water into the air to prevent erosion.
The emergency spill way just over flows into dirt and finds its own way to the river (although they did attempt to clear trees and brush).
My question is, if the emergency spillway can dump the overflow into a unimproved dirt, why bother with the regular concrete spillway?
Oh, perhaps they never expected to use the emergency spillway and so no thought was given if it was in fact had to be used.
I did see they attempted to put large rocks and cement at the bottom of the emergency spillway because I presume fear of erosion. If that fear is justified, wouldn’t it had made more sense to build it into the dam at the time of construction? It appears too little too late.
So what happens when the amount of water continues over the emergency spillway and begins to erode under the dam?
The rain has stopped. For a day or so, however there is another storm on its way. Also, there has been record snow fall in the mountains, when it begins to melt there will be more water into the lake.
This problem is not going away even if there was not another drop of rain.