Truthfully, I am surprised by the clarity, too. When driving alone it this morning at 6:30 it looked muddier than it does now, but still not too muddy to fish. When I just walked down to the river (I was directly across from the Lewistown/Victory Park boat launch) I am estimating the river clarity at about 2 feet or more, meaning that if I was in two feet of water I could see the bottom.I didn't doubt it was low enough to fish based on your description, but I am impressed by the clarity. I definitely missed some fishing opportunities this year. I should have known because I have seen pictures at other rain events where the river was much clearer than I anticipated. I often wondered if they were taken the day before. Live and learn I guess. It's under an hour drive for me, but the issue is not getting work done that needs to get done sometime.
Clarity can change at any flow and at any given time. I have seen a short, 20 minute thunderstrorm turn the Juniata into chocolate milk and yet no change in flows happen. Either way, I wouldn't consider the river blown out until the gauge in Lewistown would go well over 12 feet or so. But, as I said, I generally use familiar landmarks instead of the gauge.