Do small shallow bodies of water have a thermocline?

[Handy]

I fish mainly smaller bodies of water 44 acres and less and most of them are 13ft deep at best except one that tops out at 22ft deep(it's the one that's 44 acres). While doing some winter reading I came across the section in my book about thermoclines and got to thinking does one form in small shallow bodies water? I have not seen any signs of one on my sonar but I have not really tinkered with the settings much on it. Anybody experience this on small shallow waters? Thanks.

Paul

[roadwarrior]

No.

In small ponds the water mixes. To form a thermocline, the cooler and warmer water separates. Generally, it requires deep structure or pockets where colder water settles. Rivers never have thermoclines, but deep reserviors in the middle and northern parts of the country almost always experience this phenomenon.

[ABC123]

That 22 foot deep one could have one form, but not the shallower ones. Up here in MN, shallow 10-15 foot lakes experience freeze outs becouse they don't have a turn over.

[Paul Roberts]

I fish small waters too. My deepest is 18 feet. I've taken temp profiles as I fish -part of my journaling and general interest while fishing. My ponds warm all the way to bottom. In mid-summer, here in CO, the surface may hit 86F, with a bottom temp at 14 feet at 79F.

Wind plays a big role. If your pond at 22 feet is steep sided and shrouded in forest, it could potentially stratify. But if wind can penetrate, likely your pond mixes.

[BaitMS]

Have you ever gone swimming in any of these lakes?

If so, when you went swimming and your legs were dangling or you dove under the water did the water below feel cold compared to the water at the surface. If yes, then there was a thermocline.

[roadwarrior]

Thermocline:

http://ww2010.atmos.uiuc.edu/(Gh)/wwhlpr/thermocline.rxml

[Paul Roberts]

BaitMS,

The definition of a true thermocline is more rigorous than that. What you are feeling surface heating as heat does not penetrate water well. Heating enough to penetrate the depths takes time over the season. Most shallow waters cannot maintain the reservoir of cold water needed to create a tru thermocline.

Are those warm and cold bands you feel important to fishing -they sure can be!

[BaitMS]

Sorry, I was trying to make it easy to understand. But that is exactly what it is. A thermocline is an obvious temperature difference between the hypolimnion and the epilimnion. It has historically been defined as the region where water temperature changes are greater than one 1 C per meter of depth. The lakes that Handy refers to most definitely are capable of creating a thermocline, but this stratification may not last very long. Because of the depth, wind energy, water temperature, and lake morphology.

And heat is not what is warming the water. It is the energy from light known as photons. The intensity of these photons is what makes the water molecules more "active" which inturn warms the water. Turbid lakes warm faster because of particulate matter in the water, where clear lakes warm slower. Again, the lakes Handy is referring to I suspect are clear systems which inturn would warm slower and the hypolimnion would be more pronounced, the surface would warm first, and a thermocline would be produced.

Just my $.02.

[Handy]

I have noticed a temp difference in my friends pond and one of the smaller bodies I fish(that I have swam in). Compared to the surface temp my feet felt cold and when you dive down you really could feel the change. This ussually takes place around 6 ft deep(I know beacause I am a little over 6ft tall). All of my local fishing holes have algea blooms with the largest being the clearest with visibility up to 6ft+-. The others only have visiblility to maybe 2ft(sometimes less) except in the fall they will clear up a little bit. But 2 years ago one was almost gin clear wich was very cool because I could see what the bottom looked like. OK, there is a temp change I know for sure, how would this change how and where I would fish and do you think there would be 02 in the cooler layer at the bottom? In the heat of the summer would fish be there instead of the warm upper layer?

Paul

[Randall]

Yes. Thermocline by definition is a temp change. Nothing else is involved other than temp change as decribed by Bait MS above. Small lakes and ponds can also stratify forming distinct layers and a hypolimnion which can have reduced oxygen or no oxygen. There are a number of factors which can influence this process and the amount of DO in the hypolimnion like current, temp, wind, fertility, water clarity etc. This does not mean that all ponds and small lakes stratify because some don't. This process does not require deep water either and I have found thermoclines as well as reduced DO in deeper depths of ponds no greater than eight feet max depth. Another thing that makes small ponds different than larger bodies of water is the fact that the lake may develop a thermocline during the day in some cases that may disappear at night with cooler temps and reform during the day. A thermocline in a small lake or pond may also be totaly eliminated by a heavy rainstorm and then reform quickly the next day with hot temps. Thermoclines and stratification are more unstable in smaller bodies of water.

Handy, there is no simple answer to your question with out knowing the ponds exact makeup and current conditions at the time you are fishing. But, from looking at a few clues you have given in your last post Algae blooms and low visibility would tell me your lakes are probably very fertile and have a better chance of having low DO in deeper water which would have me fishing shallow first. Most of the lakes and ponds I fish in summer are much like this and most of my  fish come from shallow water.

[Randall]

Handy, I also just noticed you are in Iowa and your summer temps may be less than mine here in GA which could also make a difference in your ponds and lakes from the ones I fish.

[Handy]

Randall, summers where I live run in the high 80's quite routinely and can have frequent jumps into the 90's, with high humidity too(80-90%). I was thinking about dragging a carolina rig around in deeper water last year but never got to it. Now I am thinking I need to pick the right spot to do so ie cover or structure. Right now in Iowa though the water is very cold with 22(at least) inches of ice on top.

Paul

[roadwarrior]

** MODERATOR NOTE **

Handy, I hope you found some helpful information in this thread, but it drifted off track and required a little surgery. We're going to close this one down, so if you have more questions or others have comments on this topic, start a new thread.

-Kent  a.k.a. roadwarrior

Global Moderator