• BigMoe@lemmy.zip
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    11 months ago

    Found this explanation,quoted from the writer:

    Listen carefully—that’s eight short blasts. I asked a NorthWestern Energy worker what catastrophe would trigger such a warning. Dam failure, he said. Of course. This was on Ryan Island just downstream of Ryan Dam. (Ed Kemmick/Last Best News)

    • rtxn@lemmy.world
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      11 months ago

      It doesn’t have to be a failure, sometimes just opening a spillway is enough to flood certain islands. I’ve seen a video (probably Tom Scott, but not sure) of a dam where the spillway is opened every day to show tourists what the downstream river looked like before it was constructed.