One interesting point he makes is that the emergency spillway had trees growing all over it, which should never, ever happen. It must be a smooth, unobstructed hillside. When water hits those trees, they go over and the root balls pop out, creating large holes which is where the erosion begins. It is specified in this design and for inspections that these hillsides be free of foliage. So who was inspecting this thing?
I just finished listening to that interview. Interesting stuff. He said that this is the first time the emergency spillway EVERT had water over it. It was built in 1968.
I don’t think that they ever anticipated using the emergency spillway. Which was rather short-sighted as it turns out.
Thanks. I think I’d seen it before, but hadn’t read it. There are some great source docs in the comments, like the filing by Sierra Club et al a dozen years ago asking that the emergency spillway be covered in concrete, among other things.