Apparently, water @ 100,000cfs smashed them to smithereens, returning them to their aggregate state, cement notwithstanding.
Holey Moley :-\
Well ain’t that just the way it goes...
For two weeks they’ve been having to buy rock
to fill holes up on top of the emergency spillway, and
now, all of a sudden, they’ve got 1/2 million cubic feet
of free rock and have to figure out what to do with it.