[tomkat]

Mostly correct.

Main danger is the earth/stone fill under the concrete section of the emergency spillway being eroded away, causing failure of part of the concrete section above, most likely via a V notch breach.

[meyer]

Main danger is the earth/stone fill under the concrete section of the emergency spillway being eroded away, causing failure of part of the concrete section above, most likely via a V notch breach.

Thanks - I'm just thinking that as the soil under the concrete erodes, then there may be a big hole soon between the lake and the land below. That hole will erode to a huge passage if it happens.

[WildHighlander57]

V notch effect & dam construction post by an engineer

https://www.linkedin.com/pulse/oroville-dam-failure-scott-cahill