[Obi_Juan_Kenobi]

> At which point losing containment is generally a matter of when not if.

No, it's not. The local geology is fairly solid rock. The overflowing water will wear down the overlying soil and loose Earth, but should be sustained by the rock formation. It is a risk, certainly, but such a site is chosen because of the suitable foundation.

The issue right now is to see how the spillway fares over the night. If it handles the increased flow, then it should be able to continue to relieve the situation.

To be fair, I think it is a little ethically troubling to refer to the emergency spillway as anything other than that (e.g. auxiliary spillway), but it is designed to function in an emergency, not just fail catastrophically.

[PuffinBlue]

I'd love to get a source on this info. I've been looking for info on the geology of the exact area and the dam construction to assess this exact point.

Where did you find the info on the area being solid rock?

That would go a long way to giving an idea as to how bad any increased failure might be.