Hebgen dam

I haven't posted anything in a long time because....I didn't
have much to say. But here's an interesting story:

Sarah Palin is a space alien, oops, no, that's the wrong story.
What is interesting is Hebgen dam right now.
About a week ago a vertical square tube of reinforced concrete,
that forms the output flow for the dam, imploded insward, suddenly
allowing 3500cfs flow out the tube.

Montana Power made a press release saying they appologized, but they
would have it all under control soon. There was no danger, they said.
But in the mean time all campgrounds downstream of the dam are closed,
and the fishing sucks. This is peak late June flow level.

I started thinking about it, and I suspected this was a lot worse than
they were letting on. The collapsed outflow tube is a good thing for
the fishery. I sucks the water off the bottom of the lake, so the
outflow stays cool in summer. Without the tube, the damn would
have to flow out over the top, using emergency overlow channels.
But any over-the-top flow in summer would be a fishing disaster, because
it would turn the Madison into a smallmouth bass fishery.

Mt Power said not to worry. They would lower a heavy steel
somethingorother down around or into the tube to restrict the flow.
Today they announced they'd given up on that idea: it was too dangerous.
Trying to manipulate equipment and heavy metal plates in deep turbulent
water just wasn't working out the way they wanted it to.

So what happens next? They'd better figure something out fast.
If 3500cfs goes over the damn all winter, ice jams will wash out
every bridge between Quake Lake and the dam at McAllister.
Uncontrolled ice dams might knock the willy off that damn dam too.

I worked a winter on an oil rig once, when I was young. At one point
we did a "work over rig" where we cut off a crumpled casing 2500 feet
down, rethreaded the casing and re-cased it, all with natural gas
leaking around us the whole time. No smoking within a mile of the rig
and they had special spark arresters on the big V-12 diesels that ran
the rig. That was bad, but possible. But if you add huge swirling
currents and water pressure into that mix, then you begin to understand
how difficult it would be to fix an outflow tube deep down at the bottom
of a lake. They could plug it in various ways. But then the water will
go over the top, which would be summer time fisheries disaster.

To fix the tube, they might have to drain the lake. They didn't say
that. But I did.