Global Moderator 12poundbass Posted June 29 Global Moderator Share Posted June 29 The wife and I went out fishing last night. The thermocline was at 12’, then I came to this area and saw what appears to be a second thermocline deeper. This area of the lake was the only place I found this. Is this indeed what I’m seeing? 2 Quote Link to comment Share on other sites More sharing options...
Super User Jig Man Posted June 29 Super User Share Posted June 29 I’m not an expert by any stretch of the imagination but it looks like it to me. We don’t normally see them in less than 30 fow. Quote Link to comment Share on other sites More sharing options...
Super User casts_by_fly Posted June 29 Super User Share Posted June 29 Physics says that won’t work. At least not in an equilibrium state. Probably a nearby stream or spring flowing in causing some stratification below the regular thermocline. 2 Quote Link to comment Share on other sites More sharing options...
Super User slonezp Posted June 29 Super User Share Posted June 29 The one thing I don't see is fish. You should be able to change the settings on the graph to get a crisper image. I'm going to say the top line is a thermocline and might tend to agree with @casts_by_fly that some kind of current or gaseous discharge from dead and decaying carbon. Or just a phantom return 1 Quote Link to comment Share on other sites More sharing options...
Super User scaleface Posted June 29 Super User Share Posted June 29 I was hoping someone with more knowledge than me would weigh in. I'm guessing the bottom band is the true thermocline and the upper band is algae and/or other stuff. 1 Quote Link to comment Share on other sites More sharing options...
Global Moderator 12poundbass Posted June 29 Author Global Moderator Share Posted June 29 @casts_by_fly it could be a spring, I didn’t think about that. There is a creek that feeds this lake but, it’s on the complete opposite side of the lake from where this is. @slonezp I’ve never played with the settings to get a better image, maybe I should. I did see plenty of fish in others areas hugging that 12’ mark where the thermocline is in other areas. @scaleface I’m certain the thermocline is at 12’ because as we made our way around the lake it was consistently at 12’ and this was the only area where I saw this line deeper than 12’. 2 Quote Link to comment Share on other sites More sharing options...
Super User Team9nine Posted June 29 Super User Share Posted June 29 Thermoclines don't have to be just a single small zone of water. Though there are several different ways to define a thermocline, many often referring to just the zone of greatest temp change, but by technical definition, the water (zone) dropping at least 1 deg. C per meter of depth is a requirement. On larger thermoclines, you can have an upper and lower level to that band of falling water temps ('top' and 'bottom' of the thermocline). So you can have a large band of water that meets that technical definition, especially early in the year, like now, when stratification hasn't set up well, yet have certain depth levels within that larger area where you have more dramatic drops than the rest of the overall zone. The chart below from a local reservoir demonstrates this well. The area highlighted by the red band represents the thermocline by the technical definition, yet you can see two smaller depth ranges where there is a significantly greater drop in temp over a shorter range (gray boxes) which might be enough to show on a graph similar to what you posted. That said, and as has been mentioned by others, there are other possibilities that could explain what you saw on your graph depending on exact weather and water anomalies in your area. One thing not mentioned yet since you mentioned "night," is the bottom band could simply be zooplankton or similar making a migration upward in the water column due to a low light situation (referred to as a "diel migration"). This is very common in summer on some of the reservoirs I've fished. So short answer - maybe, maybe not 8 2 Quote Link to comment Share on other sites More sharing options...
Super User A-Jay Posted June 29 Super User Share Posted June 29 @Team9nine Dropping the Knowledge ~ Nice. A-Jay 3 1 Quote Link to comment Share on other sites More sharing options...
Super User WRB Posted June 29 Super User Share Posted June 29 Multiple thermoclines are common in lakes with power generation. Night explains the posted screen shot with plankton layers that often clutter out the screen. Tom 2 Quote Link to comment Share on other sites More sharing options...
Super User Catt Posted June 30 Super User Share Posted June 30 3 hours ago, A-Jay said: @Team9nine Dropping the Knowledge ~ Nice. A-Jay 3 Quote Link to comment Share on other sites More sharing options...
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