Term: "Lake has turned over" ???

[bobo1]

What does this term mean? I've heard it used re fishing reports and why the fish aren't biting...Bob

 

[NelsonQ]

Re: Term: "Lake has turned over" ???

I pulled this from the web, as it explains best.

In many lake basins the water has notable patterns of circulation. This circulation is mostly a vertical mixing of the water. It has been called an "over-turn" or "turn-over" of the lake.
The circulation or mixing is usually wind driven and is facilitated when the lake has a uniform (or near uniform) temperature from top to bottom.

If you want greater details, here is where I pulled the info.

 

[SnappingTurtle]

Re: Term: "Lake has turned over" ???

“The key to this question is how water density varies with water temperature. Water is most dense (heaviest) at 39? F (4? C) and as temperature increases or decreases from 39? F, it becomes increasingly less dense (lighter). In summer and winter, lakes are maintained by climate in what is called a stratified condition. Less dense water is at the surface and more dense water is near the bottom.

During late summer and autumn, air temperatures cool the surface water causing its density to increase. The heavier water sinks, forcing the lighter, less dense water to the surface. This continues until the water temperature at all depths reaches approximately 39? F. Because there is very little difference in density at this stage, the waters are easily mixed by the wind. The sinking action and mixing of the water by the wind results in the exchange of surface and bottom waters which is called "turnover."

During spring, the process reverses itself. This time ice melts, and surface waters warm and sink until the water temperature at all depths reaches approximately 39? F. The sinking combined with wind mixing causes spring "turnover."

This describes the general principle; however, other factors (including climate and lake depth variations) can cause certain lakes to act differently. A more detailed description of the physical characteristics of lakes, including temporal and density interactions, can be found at the Water on the Web site, sponsored by the University of Minnesota - Duluth and funded by the National Science Foundation.”

Credit for this goes out to “OzzieFish” over at texasfishingforum

 

[cbavier]

Re: Term: "Lake has turned over" ???

I pulled this from the web, as it explains best.

In many lake basins the water has notable patterns of circulation. This circulation is mostly a vertical mixing of the water. It has been called an "over-turn" or "turn-over" of the lake.
The circulation or mixing is usually wind driven and is facilitated when the lake has a uniform (or near uniform) temperature from top to bottom.

If you want greater details, here is where I pulled the info.

But what we see to testify of a "Turning Over" is the vegetation floating on top. Is this from the Vegetation disrupted and washed up to the surface or is it a dying process of the vegetation from the bottom of the lake? ANYBODY ? I do know when this vegetation is present on the surface the fishing is very poor.

 

[NelsonQ]

Re: Term: "Lake has turned over" ???

cbavier, I haven't experienced vegetation on top in the lakes I fish. But, we have quick temperature drops and perhaps it does contribute to the vegetation simply dying on bottom. Interesting question. Has anyone experienced this?

 

[gonefishie]

Re: Term: "Lake has turned over" ???

It is the dead decayed vegetation pushed up to the surface by the methane gas, which is produced from decaying vegatation and kept on the bottom by the heavier water, sometime in bad cases caused foul odor and the greenish water color. Fishing is bad during turn over or stratification because the dissolved oxygen level in the entire column of water is about even so fish are more spread out. Different species have different comfort level of environment factors and during this short period of time all bets are off. You're not catching fish or "they're not biting" because your bait is not where the fish are. The last issue of FLW Outdoors Mag. have a very good article on this subject. I am not a scientist but I did stay at the holiday inn express a while back.

 

[SnappingTurtle]

Re: Term: "Lake has turned over" ???

On the north Texas lake I grew up on this happens every year, and is always accompanied by a very strong, over powering smell of methane gas, and a bubbling of the water as it rises. The occurrence of dead and rotting plant life on the surface is also present in the calmer waters.

You can catch fish while this is happening, you just need to take the conditions of what is happening in the water into consideration, and modify your normal fishing methods to account for this. I am not an expert at this, but the guys I fish with when home are. I just do what they tell me to. Don't catch as many, but enough to still make it fun to go out.

 

[cbavier]

Re: Term: "Lake has turned over" ???

gonefishie & SnappingTurtle you are both right. Thanks for your imput. Lake Turn Over does pose a very strong, over powering smell of methane gas, and a bubbling of the water as it rises, the green slime is Putrid. I have fished for 50 some odd years and was always taught that all Lakes turn over about every seven years, but I have learned in the past four or five years that. That isn't always true. The smell and green slime sometimes gets so bad I give up trying to fish or usually move to a different area of the Lake.

 

[ebry710]

Re: Term: "Lake has turned over" ???

I had learn about turn over in school years ago, but I have never been able to visualize the up evil it causes in the real world. It is real neat what nature does to clean itself. Thanks for this forum.

 

[gonefishie]

Re: Term: "Lake has turned over" ???

gonefishie & SnappingTurtle you are both right. Thanks for your imput. Lake Turn Over does pose a very strong, over powering smell of methane gas, and a bubbling of the water as it rises, the green slime is Putrid. I have fished for 50 some odd years and was always taught that all Lakes turn over about every seven years, but I have learned in the past four or five years that. That isn't always true. The smell and green slime sometimes gets so bad I give up trying to fish or usually move to a different area of the Lake.

Lakes in cold climate should stratify every year except for those that have current or are very deep. Our southern and western neighbors don't experience this phenomenon. In my neck of the wood, there are many reservoirs that are used for flood control so they're basically void of aquatic vegatation. During "turn over" you can't really tell if it's happening or not.

 

[bobo1]

Re: Term: "Lake has turned over" ???

Wow! You guys are a wealth of information! Thank you for responding to my post. I feel smarter now. Well, maybe not smart enough to be on Jepardy...Bob

 

[Tacklewasher]

Re: Term: "Lake has turned over" ???

Got a book around here somewhere that explains it, but, at least in this part of the world, the reason why the fishing is off is the impact on the oxygen.

Over winter the plants die out and start to rot. This takes oxygen from the water at lower levels. The upper levels still have O2 under the ice, although it can become depleted and the lake will winter kill. Once the ice is off, the wind will replenish the O2 and the fishing is great. Then the lake turns over like Turtle described. The O2 depleted water comes to the top and mixes. With less O2 overall, the fish become less active and fishing can be off for a week or so. In extreme cases, there is a fish kill.

Very common on small to middle sized lakes.

 

[Starcraftguy1]

Re: Term: "Lake has turned over" ???

I go to a lake here in Arizona called San Carlos Lake.we went up last October the weather had changed it was 38 degrees at night,very cold for here.Two weeks before that we were catching crappies by the tons,the lake was clear and good.That weekend in October after the lake had turned it was muddy,no shad came to the lights,the only thing that we caught were flatheads on chicken livers at night.A complete change in two weeks.

 

[Mark_VTfisherman]

Re: Term: "Lake has turned over" ???

Got a book around here somewhere that explains it, but, at least in this part of the world, the reason why the fishing is off is the impact on the oxygen.Over winter the plants die out and start to rot. This takes oxygen from the water at lower levels. The upper levels still have O2 under the ice, although it can become depleted and the lake will winter kill. Once the ice is off, the wind will replenish the O2 and the fishing is great. Then the lake turns over like Turtle described. The O2 depleted water comes to the top and mixes. With less O2 overall, the fish become less active and fishing can be off for a week or so. In extreme cases, there is a fish kill.Very common on small to middle sized lakes.

Old thread but:

There is more to why fishing is off after turnover. Fall turnover is what we talk about in the northeast. That happens when the water temperature at the surface drops to a point that it is close to or equals the thermocline temps.

The thermocline is the layer of water that is both cold and has enough oxygen. Below the thermocline is the really cold layer which has very little dissolved oxygen. Plantlife aside, when the temps equal out, the whole lake then mixes- "turns over". Yes, you get the junk, the slime, the weeds at varying amounts in different lakes, but when the water mixes, then the oxygen AND temps get distributed over the whole lake.

When the whole lake equalizes, the fish-concentrating components- temperature zones, oxygen levels, and baitfish schools- are eliminated or reduced, spreading the gamefish out. So while other issues mentioned may play a part in the whole fishing experience, lake turnover in northern climates is not a mysterious phenomenon, but is an expected event or circumstance.

In winter, water under the ice can depletes its oxygen. Plant decay, etc. can contribute. The air cannot stir up the water surface and entrain it with oxygen. That is what causes winter kill, especially in lakes that do not have a great deal of volume to hold oxygenated water over winter, or a hard-running river inflow to bring in O2.

In spring, a lake does not "turn over" again, but water bodies start to "stratify" by temperature, and other than high wind activity, the layers essentially (especially in deeper lakes) do not 'mix' again until fall. This stratification is what creates the "thermocline".

At least in the northeast, turnover happens every fall in any and every sized lake except for maybe shallow ponds, caused by the same thing that makes ice float. Vermont isn't Arizona though

 

[cbavier]

Re: Term: "Lake has turned over" ???

Mark: Your explanation makes sense but here in Northen Michigan. We never get turnover or the weeds and slime in the fall. It's always in the Spring and early summer. We are as or nearly as far north as you are so something else must play a part in turnover also. The Thermocline must be different and I am on a deep lake. Some places are over 100 ft of water deep. However the worst seem to be in 30 ft or less of water

 

[Mark_VTfisherman]

Re: Term: "Lake has turned over" ???

Mark: Your explanation makes sense but here in Northen Michigan. We never get turnover or the weeds and slime in the fall. It's always in the Spring and early summer. We are as or nearly as far north as you are so something else must play a part in turnover also. The Thermocline must be different and I am on a deep lake. Some places are over 100 ft of water deep. However the worst seem to be in 30 ft or less of water

I just knew different regions were going to comment on a different experience when I wrote that Just didn't know who or where

The best example I have is Lake Carmi- a walleye/bass/pike lake. One small nearly 40' hole, but generally 20-35' deep all over. we fish 12-24' usually. The green slick of algae, course of floating trash, and sudden clarity (on my sonar) on the side of the lake that usually comes up mostly black until I turn the gain down, showed that something had happened since our last visit last fall. I have seen it before, too.

Never seen the effects in spring: seems like every lake is always full of junk after ice-out but I have never attributed that (or seen an explanation of it as) turnover.

Trout closes in october here in VT so haven't usually seen that evidence on those lakes.

 

[cbavier]

Re: Term: "Lake has turned over" ???

I wasn't disputing you but just stating a fact of my observations. I have always thought there was a lot of misconception about Lake Turnover. I have always thought perhaps heavy snow on the winter Ice killed the vegatation because of the lack of sunlight and that caused the spring floating vegetation and really didn't have anything to do with Lake Turnover.

 

[Starppy]

Re: Term: "Lake has turned over" ???

I read all the posts and everyone seems to dance around how simple the concept really is. It is basic physics. Cold water is heavier than warm water. In the summer, the water near the surface is warmer and lighter since the main source of heating is the sun. During the summer the water in a lake stratifies with warmer, lighter water near the surface and colder water the deeper you dive.

Thermoclines mark a boundry between two layers of water that have significantly different temperatures and densities. These boundries vary depending on many factors including, but not limited to the amount of wave action/mixing, the penetration of sunlight and amount of debris/algea in the water.

In northern climates, the condition is reversed as winter approaches. As the days get colder and drop below 40 degrees the surface water cools below the temperature of the water at the bottom of the lake, becomes more dense and begins to sink. At the same time, the warmer water at the bottom of the lake rises and so in that way, "turns over", "flips", or "rolls over". It isn't just a one time thing either. The bottom never freezes and maintains a temperature in the low 40's while the frozen surface is at 32 degrees. All winter long the turn over continues until ice out in spring.

Once the ice is gone, the water stabilizes again and the warming days and high sun angle begin warming the surface and the whole process start over again. This only happens in northern areas where the surface temperatures drops below 40 degrees for extended periods.

 

[Mark_VTfisherman]

"Lake has turned over" ???

"Lake has turned over" ???

I wasn't disputing you but just stating a fact of my observations. I have always thought there was a lot of misconception about Lake Turnover.

I didn't think you were disputing me either- I just expected that the northeast was probably not the same as other areas of North America.

It's cool. I am learning a lot here. I appreciate your part in that.