The water level drop will usually concentrate them in the channels, either down in the channel or along the edges. If water is still actively being drawn out of the lake at any appreciable rate, they should react to it the same as they do in rivers .... concentrating in eddy water areas, like the inside bend of a channel or the down flow side of a bridge pillar.
"Turnover" is simply the upper layer of water getting colder and sinking, which mixes the different layers of water. Cold water is denser than warm water, so the warm layer usually sets on top of the colder layer ... until the weather conditions drop the temps of the upper layer. Heavy discharging of the lake's water can sometimes negate that process, and even when it does occur ... it's not always throughout the whole lake at the same time. If it does occur, the water may turn dark & may have a "smell" to it, depending on how quickly the upper layer drops. The color & smell is due to the debris/muck on the bottom can get stirred up in the process. The mixing effect can turn the fish off for awhile, but the biggest effect is the mixing of temperature layers will destroy the thermocline (which was holding the fish from staying below it, because of lack of sufficient oxygen). The mixing effect will distribute the water temps and oxygen levels more evenly throughout the water column, which gives the fish more depth territory to roam in (unless, of course, the lake is drawn down a lot ... like Douglas is).
This is just "general" info, based on my experiences with some of my local lakes. Whether or not this is pertinent to Douglas or not ... .... because I haven't fish Douglas in several decades (& never in the Fall or Winter). I'll leave it up to the Douglas locals to agree or disagree with my info.