The more I see the more I think this whole mess stinks like shit. This thing is in danger of collapsing and what are they doing? They have a couple earthmovers and rock trucks with a few helos flying support. If the emergency spillway goes, there will be BILLIONS of dollars of damage and as of yet unmeasurable ecological impact (think of the farms downstream). Where is the urgency? Why are they not grabbing every yellow piece of equipment for 50 miles and dumping rip rap all over the place? Not to diminish what the guys on the ground are doing but the scale of their effort thus far does not mesh with either the severity of the mishap or its probability of happening. Either they think there is no danger of
any further uncontrolled runoff (previous 48 hrs rules that out), or they know its only a matter of time until it fails and they are triaging.
With the evacuation order lifted it seems they are in a holding pattern until the rains hit so they gave people a chance to go in and get anything they dont want destroyed. Doing some rough math, even 3" of rain over the entire 3600 sq mi watershed would be 575,000 acre ft of water which is about 1/6 of the entire reservoir's capacity. The good news is that the main spillway erosion appears to have stabilized IVO the transmission towers for the time being @ 110 Kcfs, but who knows if that rate will be enough to outflow all the rain that is coming. They will have to shut it down eventually to asses just how much has eroded.
From this fascinating pdf:
CA DWR Storage Facilities we get this drawing:
Now lets get to the weir, and what a shitshow this is turning out to be. Below notice that near the main spillway it is tall and near the parking lot it is shorter. There was a lot of speculation that it was pre poured sections of the same height all the way across which would have been the strongest construction. In reality they built it "on grade" which means they followed the contour of the rock. Further it is not even "toed" or "keyed" significantly into the rock. There is also a retaining wall in front of the parking lot that won't do a damn thing if there is a significant overflow situation. The far left portion of the weir where it meets the parking lot retaining wall is the weak link here, that area will see a lot of turbulence which will scour that shitty rock like sand. Seawater going over the watertight doors in the Titanic comes to mind.
One thing to remember is all this damage was caused by a 1.5' head of water over the emergency spillway that flowed at a max rate of 8-12 Kcfs. If there is another event with similar numbers, the hillside will erode underneath the weir and the whole thing will come down and the entire reservoir will drain until it hits bedrock at
maybe 800 feet. It is currently at around 880'. I cant believe they are letting people back in town. I want to know if the families of the govt officials, LEOs, and contractors are moving back to town. If they are not, I would not either.