Winter water temperature measurements in the water column need to be done on larger water bodies than 0.7 to 1 ac with diffuser/s set at 1/4 or less of the water depth. Example 16-18ft deep set diffuser at 3-4ft and measure the water temperatures of the water column in a few remote areas away from the diffuser/s. Diffuser can be set near one end of the pond and measure water temps at other end but still in deep water 10-16ft. What we don't know is how far and deep water currents from a shallow diffuser will mix into the winter ice covered pond. I think it will be several hundred feet or even much more. It does not take much force energy to mix water that has a uniform density. Water is a very unique substance.
In summer this becomes a whole different story because the warm water of 70+F will want to very strongly float on cooler more dense water below. The closer the surface temp water is to the dense thermocline water (uniform), the easier mixing of the two layers can occur. Resistance to mixing strongly increases more and more as the two temperatures diverge. The more surface water warms above 65-70F the stronger the resistance to mixing becomes due to divergence of water densities. Water constantly becomes less dense as it warms.
Natural wind mixing of summer surface water into depths in many ponds generally occurs down to 6ft at least those in the midwest and northern states. But in large 500+ac lakes strong frontal winds can mix water down to maybe 18-20ft according to my measurements. My MS thesis lake in Ontario had an August thermocline at 23-26ft for 2700 surface acres.
Do any members have records of thermocline depth for southern ponds where summer temperatures persist longer as warm water conditions???
Anglers what are you measuring for thermocline depths of ponds or small lakes that you fish??? Let's get and record some natural summer water mixing depths for various sized USA ponds. Amount of direct wind exposure will have a big influence on natural mixing depth of ponds and small lakes. Ponds smaller than 1 acre in my NW Ohio area rarely mix deeper than 6 maybe 7ft in the larger ponds. This depth is where the natural thermocline generally starts. In sheltered clam water ponds the thermocline could commonly be as shallow as 4-5ft??
Last edited by Bill Cody; 01/14/20 04:34 PM.
