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marbleye

Lake Turn Over

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Can some explain this to me. I thought that lakes needed to get to a certain temp to turn over. I have a place in in Alex and it looks likes it's starting to turn over. Water is not clear. You can only see about 3ft down. Usually it's around 10-12' My locator is not very clear also. Also does a lake turn over in the spring?

Thanks for the help.

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Well im no genius but i believe it only happens in the fall time. The water isnt any where near the right temperature yet though. The last couple weeks have been to warm, water temps have actually gone up in most lakes around here.

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I thik what happens is. when the water warms in the summer the certain depth down you get a thermocline. A thermocline is where the water temp starts to drop really fast. and there in not enough O2 to suport big fish just small bait fish. so in the summer you will never get any fish below 20 or so depending on the lake. but in the fall when the water temp cools. the thermocline go away and the O2 leavles are back to normal and then you can find fish anywhere in the lake at different depths. I have heard of guys pulling walleyes out of 80' of water in the fall after the lake has turned over. but thats how I think the turn over works. but I maybe wrong

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You could be still experiencing some "turnover". The upper 20-25 feet of the water column doesn't stratify and mixes readily with wind. If this lake is shallow it can turn over all season. A good example would be mille lacs. You may also have an algal bloom limiting visibility.

Lake turnover occurs when all of the water is at the same density. This occurs at 39 degrees fahrenheit. Deep lakes that stratify can turn over when the water is 39 degrees throughout. The lake also needs something to mix it, such as wind or current. What lives at depth has nothing to do with size of fish. It is the fishes ability to survive with lower dissolved oxygen. Most species require a minimum of 5 ppm oxygen. Lake trout live at greater depths than many other fish, and I wouldn't consider them baitfish. If the lake doesn't mix the O2 levels will still be low to nonexistent at depth due to the use of oxygen by breakdown of sediments. Hopefully this all makes sense.

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There are a lot of things at work here. The wind will stir the lake and keep the top 20-25 feet or so mixed. As water warms it becomes less dense which changes the specific gravity of the water. Then there is the algal bloom.

What I see happening is we have had little to no wind to stir up the water, the water has been cooling and becoming more dense which is causing small particulate matter to suspend higher in the water coulomb. In other words, The fish are moving shallow!

In the winter half of the year the coldest water is on top of the lake. In the summer half, the warmist water is on the top of the lake. When it changes in the spring and autumn we call it turnover.

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Well I'm not sure about the lakes cooling. Bald Eagle still has a 75 degree surface temp. It bounced up to 79 or so on Friday. This has been an odd late summer. My guess is that what the original poster experienced was some sort of algae bloom. I don't think we're going to see turnover for a bit, at least not down around here.

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39 degrees is way past turnover on any of the lakes I fish in the fall. No expert, but the lakes I am familiar with turnover between 49-52. Just my experience. This info coming from resort owners and guides.

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39 degrees is when water is at the highest density. For complete mixing to occur the water needs to be at the same density. The closer the water is to being the same density the easier it will mix. If the coldest water in the lake is 50 degrees then when the entire column is the same temp it can turn over. Also on cold snap nights the surface water can cool rapidly and dump to the bottom, stirring up the water column. Every lake is going to be different.

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That is what I have thought turn-over was also. If the coldest temp is 50-55 degrees, surface temps 72 plus. Turn-over would be when all water is the same temp. bottom matches surface temp.

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From the DNR:

In mid-September, decreasing daylight and chilly nights cool surface waters. In summer, this

layer stayed above the cold and dense oxygen-deficient water at the bottom of lakes. But in fall,

the upper layer starts cooling and soon reaches the same temperature and density as the lower

layer. Wind then mixes the two layers and the entire lake becomes one temperature, with

oxygen distributed evenly throughout—a process called “turnover.”

Once a lake turns over, fish no longer need to concentrate near the surface or shallows, which

were the only areas with enough oxygen a few weeks earlier. On many lakes this means

walleyes can go into deeper water.

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