Was fishing naconiche (featured lake on mlf this spring) last week. Was there on vaca. For the whole week. On the main lake I could see a thermocline on my down scan pretty well at around 14 fow. It wasn't really registering on my 2d sonar screen unless you adjusted the sensitivity way too high. A good sonar setting for the main lake would turn into total trash once I got up into one of the creek arms . (So I'd have to decrease the sensitivity to get a better image.) If my 2d sonar on the main lake was capturing a good image on basically auto settungs on the main lake , but pretty much trash through out the water column up the creek arms. Does this indicate a turnover up the creek arms??

Whenever I've seen a creek arm turn over, it's obvious due to the chocolate colored water and all the trash floating on the water.  It's unmistakable.  The inversion picks up the dead leaves and other detritus and brings them to the surface.  If the creek is shallower than the thermoclines in the rest of the lake, it may never have a thermocline, especially if there is a current in the creek.

The creek arms were as far as I could tell same color and clarity as the main lake no current to speak of I noticed. No noticeable or out of ordinary debris on the surface. I'm thinking the trash I'm seeing isn't necessarily debris but warm water sinking into the cooler water reflecting a density change. But I just don't know. Also I've always heard brown lake bubbles meant turn over. White bubbles were good. 

Here there is usually a rotten smell and the water has a browish tint instead of the normal greenish. It doesn't happen here till late fall. Oct/Nov. One time I noticed thousands(literally) of crawdads alive at the waters edge everywhere during the turnover as well.

Lakes over here start turning over when the water temps hit 70 degrees in the Fall

I'd be surprised if you're seeing any significant turnover in August. Much more likely to be some biological based phenomena; algal succession, plankton bloom, baitfish, detritus, etc. as opposed to actual water density changes, IMO.