Mike wrote:
Just my .02 slide a huge metal plate down the lake side of the dam
blocking the hole.........Open up the side gate so water flows around
and not over build a new tube on the river side slide into hole secure
problem solved...........Tell them to send me the check...........

That might be what they have to do.
The radio had a few more details an hour ago.
They tried to poke a metal rod down the inside of the output
tube. That rod was supposed to guide a metal plate down the
inside of the tube, down to the rupture. That would restrict flow.
But the rod started shaking so violently (because of deep, powerful
turbulence at the bottom of the tube) it threatened to collapse
the crane that was lowering the rod.

Now they're back to head scratching.
They did mention the lake is dropping by 5" per day.
That's 150" or 12.5' per month.
Or roughly 50' drop in four months.
In other words, if they don't get it plugged, the lake
will drain by winter's end.

I assume they WILL get it plugged, one way or another.
And then (as you suggested) the best approach might well
be to build an new outflow tube, rather than fixing the old one.
That will take at least a season.

That would probably mean a lot of 75 degree water going over the top
of the damn dam next summer. Better hope they get it fixed in one season.