Dissolved oxygen levels?

Peter I think the thermocline is 15/16 ft that is the first big drop which is 2.5 degrees and you have the o2 at that level.

Technically a thermocline refers to the thin layer of water where the temperature changes more rapidly with depth than it does in the layers above or below.
As far as oxygen goes, a nearby creek flowing into the lake could cause better mixing and result in fish deeper than the levels of oxygen reported from the dam.
A very likely reason could be a nearby weed bed, they produce oxygen during daylight just like the plants that grow on land, but after dark they have the opposite effect resulting oxygen depletion at much shallower than reported. Either way if your catching fish, your in the right spot.

While scuba diving in Kentucky, I have dived through some thermoclines in warm water and seen bass living at all levels; the water temp would drop about 12 degrees every ten feet or so. We dove one time in an old rock quary and found bass lazily swimming straight to the surface up in open water.