Contricting Flow near Newville

Brian -
You have mentioned several times how the river constricts the flow from the lake and upstream. Can you explain that?
Joe
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Here's what the flow looked like on August 1st;

Lake level = 776.12
Indianford level = 775.79
3.96 inches higher at the lake than at the dam.

And today;
Lake level = 779.65
Indianford Level = 777.82
21.96 inches higher at the lake than at the dam.

Yet another example of the Dam having negligible ability to control high water. Mother Nature, and the narrowness of the river, does that.