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Posts: 267
| I might be jumpin the gun a bit here but as I look forward to an early October trip up to Vilas county, I have already been watchin' the weather. After a hot summer, it looks like there is going to be a major cool down next week with highs only reaching the low 60's and night time temps down in the 40's. My question is at what surface temp do small to mid-sized lakes usually start to turn over? I know there are many variables and some large lakes don't even "turn over" but am just curious as to what any locals or those "in the know" think. Thanks. |
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Posts: 1095
Location: Hayward, WI | My dad does lake monitoring on a 800 acre Hayward area lake and the lake turned over last week already. Lake temp is withing 7 degrees top to bottom and oxygen levels same top to bottom. There was a defined thermocline 2 weeks ago when test was last done. With the warm temps this year wierd things are happening... Lakes can turn over multiple times and I am interested to see if that happens this fall. |
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Posts: 2058
| kjgmh - 8/31/2012 11:28 AM
My dad does lake monitoring on a 800 acre Hayward area lake and the lake turned over last week already. Lake temp is withing 7 degrees top to bottom and oxygen levels same top to bottom. There was a defined thermocline 2 weeks ago when test was last done. With the warm temps this year wierd things are happening... Lakes can turn over multiple times and I am interested to see if that happens this fall.
I have never heard of any lake turning over (fall) until lake temps are in low 60's...interesting observation. Water has to be in the 70's correct?
Thermocline will become less apparent and drop deeper generally in late summer/early fall.
Edited by IAJustin 8/31/2012 12:01 PM
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Posts: 1095
Location: Hayward, WI | Here was the profile from 7/30, first number depth, second temp, third disolved oxygen; definate thermocline. Last weekend it was 71-64 temps and oxygen level was within .5 from top to bottom.
0 78.9 8.56
5 78.7 8.62
10 78.5 8.66
15 78.4 8.65
20 78.3 8.62
25 73.9 .25
30 68.9 .13
35 65.9 .09
40 63.9 .05
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Posts: 267
| That is very interesting kjgmh. Please keep us updated periodically throughout the fall. |
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Location: Eastern Ontario | My favorite turnovers are cherry and apple but couldn't the wind turnover a small shallow lake |
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Posts: 4343
Location: Smith Creek | Turnover is a myth created by fishermen to explain why they didn't catch anything. It doesn't really exist. |
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Posts: 81
Location: Bloomingdale, IL | This is the first time ive heard this term, real or not, what exactly does it mean? |
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Posts: 78
Location: In the Weeds | The term basically means that when lakes hit a certain temp the bottom of the lake turns over to the top. |
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Posts: 8823
| Crap, how to explain this... I think this is right:
On lakes that stratify during the warmer months, there comes a point late in the season where the surface water becomes colder than the water underneath the thermocline. When this happens, the surface water sinks, and essentially mixes with the entire water column. This causes two things to happen:
1. Temperatures and D/O levels will be consistent throughout the water column (no more thermocline)
2. Decaying plant matter that has spent the season on the bottom of the lake gets stirred up by the process. Since there is virtually no oxygen at those depths for most of the season, that stuff does not decompose until fall when it gets mixed throughout the water column. That's why the water is usually brown, murky, and smells bad during turnover. |
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Posts: 78
Location: In the Weeds | Thats a more accurate, and more detailed explanation than mine. Thank you
esoxaddict - 8/31/2012 4:12 PM
Crap, how to explain this... I think this is right:
On lakes that stratify during the warmer months, there comes a point late in the season where the surface water becomes colder than the water underneath the thermocline. When this happens, the surface water sinks, and essentially mixes with the entire water column. This causes two things to happen:
1. Temperatures and D/O levels will be consistent throughout the water column (no more thermocline)
2. Decaying plant matter that has spent the season on the bottom of the lake gets stirred up by the process. Since there is virtually no oxygen at those depths for most of the season, that stuff does not decompose until fall when it gets mixed throughout the water column. That's why the water is usually brown, murky, and smells bad during turnover. |
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Posts: 215
Location: Wisconsin | http://en.wikipedia.org/wiki/Thermocline
Depending on fall weather patterns, some northern lakes can experience several "turn over's" before settling down for winter. Also keep in mind that not all lakes will experience a turnover. This only occurs in lakes that are deep enough to stratify. As you said, loads of variables. My best guess is most lakes in Vilas county will start to turn in the low 50's. Ill pick 52 degrees.
Hope you nail a trophy on your Oct trip! |
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Posts: 4080
Location: Elko - Lake Vermilion | Also some larger lakes will have 2-4 larger basins that may turn over weeks apart,,,,,,...( I'm talking 40,000 acres or more) and some areas on the same lake won't do anything .....
55-50* water temps are usually when turn over seams to go.. Up Nort.
Edited by Top H2O 8/31/2012 6:43 PM
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Posts: 605
Location: Marshfield, WI | Not all lakes turnover at the same time. So if you go to a smaller lake on your trip and it is turning over, find a larger lake as those probably haven't turned yet. |
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Posts: 246
| Top H2O - 8/31/2012 7:41 PM
Also some larger lakes will have 2-4 larger basins that may turn over weeks apart,,,,,,...( I'm talking 40,000 acres or more) and some areas on the same lake won't do anything .....
55-50* water temps are usually when turn over seams to go.. Up Nort.
What he said and rivers since they are constantly mixing never form a thermocline will not experience a "turnover"
Edited by zombietrolling 9/1/2012 9:04 AM
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