Poor design and poor maintenance.
Everybody knows that you can’t have flowing water on an earthen dam. The emergency dam to the left of the spillway is concrete atop a earthen dam. Water is overtopping the emergency dam and eroding the earthen base.
The emergency concrete spillway was damaged and never repaired.
That's the main spillway. And that hole is kind of "cosmetic", to tell you the truth, it just goes down to bedrock and that's the end of it. It is eroding to the sides which is kind of messy. But the hole is nowhere near the lake -- it is far back through the hill.
That’s what I’m starting to wonder.. is this a planned failure?
Either A) the engineers, at design, never dreamed there could be rainfall like there has been recently (unlikely), B) Engineers assigned to the dam are crooked and not reporting decay - and where is ACE on this?! - or C) somebody wanted that dam to fail.
Never attribute to stupidity that which is explainable by malice.