[GOPJ]

What is also interesting is that this 2foot diameter drain is close to the opposite side of where the bubbles occurred. That drain pipe may have been a good indicator to any increased water underflow to the substructure of the ES Weir when flood levels occurred (just before and just after the cresting of the Weir).

Underflow would threaten the main damn structure, right?

[meyer]

Underflow would threaten the main damn structure, right?

In this case, it would threaten the aux/emergency Weir and not the main dam. Which is still a very bad thing, because while the dam would survive, losing the weir would result in a washout of a good amount of ground that would bring a lot of water down at one time.

I don't think that the water dribbling out of the 2 foot pipe is necessarily a bad thing. The area has had a lot of rain and the ground is saturated. This could easily be just excess water that has soaked into the area soil. Depends on where the drain goes.