Thermocline

[NorthE97]

Been trying to figure out my electronics as I'm still relatively new to them. This is a Garmin Striker 5cv. Was probing my lake to see if there is a thermocline in it. Went to the deepest part (24ft) and came across this band around 5-10 foot mark. As I zoomed in it was more 6-8 foot mark. I went around for a bit and kept getting this mark. Was wondering if this could be a thermocline?

 

The lake is electric only, 500 acres. Relatively calm coves but the main body gets its fair share of wind and there is a dam that generates a little surface disturbance. 

 

However, I've also seen what appear to be fish arcs on the bottom when I'm in 16ft of water. This finding would contradict the thermocline. 

 

Edited June 24, 2019 by NorthE97
Resized picture and added new comment

[MN Fisher]

Sure looks like a thermocline band to me. My last sonar (10+ years ago) was a grey-scale unit and it showed up as a hazy, gray band on that one.

[Team9nine]

Too hard to tell without seeing the entire screenshot. Better to resize than crop.

[NorthE97]

20 minutes ago, Team9nine said:

Too hard to tell without seeing the entire screenshot. Better to resize than crop.

Resized 

[Team9nine]

4 hours ago, NorthE97 said:

Resized 

Thanks. Honestly, hard to tell from the pic and not knowing the lake. Water temp seems a little cool to be thermoclining already. Any chance the lake has been treated for weeds recently? Everything seems to be in the upper level of the water column, but it could simply be a case of warmer surface waters attracting everything (without a thermocline technically). You said you saw arches down to 16', but they don't appear in that screen shot and would be deeper than a potential thermocline making a cline unlikely.

 

The best way to definitively tell is always a temperature probe with a long cable. Getting a little hard to come by these days at an affordable price, but I carried one around for years whenever I questioned what was happening on the graph or just wanted to know the temp profile of the lake.

[Tennessee Boy]

I’m thinking it some kind of surface clutter that probably goes to the surface but is being filtered out at the top.   I’ve personally never seen a thermocline that shallow but I’ve never seen 72 degree water in late June either.

[NHBull]

I have seen this randomly and recently and was told it was dur to the extra ordinary amount of pollen sinking because of surface wind.

Locals say this is the worst they have seen in decades.  I was not aware it was possible as I also thought thermocline, but is would be the easiest I have seen. Our water Temps are mid 60's 

[Sprocket]

I would guess plankton or pollen.  But that's just a guess.

 

SE Kansas grass grower

[NorthE97]

Thanks for all the replies everyone. I'm leaning towards it being some kind of clutter, (pollen/plankton/etc.) Next time I go out I'll target those fish in 16' and find out. I also might just jump in and see if I notice a significant temperature drop.  

[WRB]

The clue to not being a thermocline is variance in signal density, you are looking at Phytoplankton would’ve my 1st thought.

Tom

[gim]

Can a thermocline even develop in a lake that’s only 24 feet deep? I thought they only were present in deeper bodies of water when it was warmer out. Our lakes up here in Minnesota usually don’t even have one.

[WRB]

Thermoclines soften developed in shallow ponds requiring areation systems (fountains)  to mix the water layers adding DO.

All that is needed is 4 degree temperature change within a few feet.

Tom