Slabseeker1 .... those COE charts are a little outdated, plus they show the O2 levels to be too low for fish survival (<5mg/L) ... for any length of time, anyway. Luckily they are taken at the dams, so they're not indicative of the overall condition of the lake.

This chart probably shows why the O2 levels are so low .... not much change in water levels, and not much new water (rain) added to the lake in Sept:



But, your chart does show a consistent temp down to the 20-25' depth range, before dropping to any degree. I'm not sure that's indicative of a thermocline, or the slow degradation of one, but it definitely shows that "turnover" is still a ways off.

Green River Lake COE charts are very similar to the Barren River Lake COE charts of the same time frame (mid Sept) ... as far as temps/O2 depths and the lack of any substantial Sept rainfall.

(no disrespect intended, just adding some info to the discussion)