If the emergency spillway goes, that's 30ish lake-feet of water that would drain uncontrolled. That would likely wipe out a few towns down the river.

I think gp was getting to the fact that the main spillway is eroding as well, and it could reach a point where it was unusable. In that case, with significant rainfall expected in the next week and a good deal of snow melt to follow, there could be huge amount of water coming into the basin with no way to control the outflow, which could result in much worse flooding.

Hopefully that all can still be avoided. It's a bit dramatic to say it's inevitable. It's a possible scenario, but it's also possible the right plan avoids it.