Originally Posted By: CT8
I used to water ski at lake Berryessa I have wondered why the Glory hole design.
There isn't a reasonable location for a spillway alongside of the dam, and the concrete arch construction of the dam makes a spillway down the face a problem -- it would be a vertical waterfall that would undermine the base. So an interior spillway is used. Using sharp angles results in turbulent cross-flows that might erode the surface, so a rounded intake is used. The roundest shape is a circle.