Good post, thanks Tim. Cindy's pond builder wants to put the lower level at 5 ft. below full pool. He's a conservative type and I think he's concerned about maintaining enough water. Similar to your situation I think. I was thinking 3 ft below full so maybe we'll settle on 4 ft. Or maybe I'll just be smart and listen to him.
One difference is that we're going to go for the most gradual slope we can on the face of the dam. It will depend on how much material we have because the dam is very long. I designed the dam opposite of most people I think, with the back side having a very steep slope that I'll let go wild except for any trees that sprout up.