Pond Hopping – Turnover

Pond Hopping – Turnover

Oct 14, 2012

The Turnover Conundrum

By Mike Pehanich

Fall fishing can be some of the season’s best.

Why then — aside from hunting — do many anglers hang up their gear after autumn’s first bad outing?

The author found this post-turnover largemouth at 36 feet deep on a northern natural lake. This bass probably had not seen this deep structure all summer. Photo by Cory Schmidt


If you are not familiar with the phenomenon, “turnover” refers to that peculiar development that occurs on lakes that thermally stratify. As the term indicates, the water on the bottom suddenly rises, spreading all the dead matter and associated toxins that had been trapped below the thermocline through the entire water column.

Here’s the short explanation. The turnover process is a function of water temperature. Water is heaviest at about 39 F degrees ¬†(4 C degrees). During summer, the warmest water sits at the surface. Think of yourself as a diver. On a lake that stratifies, water temperature slowly drops as you descend the water column until you reach the thermocline, a layer where water temperature becomes suddenly and noticeably colder. The thermocline creates a barrier that prevents the water below it to rise. All the dead and decaying matter of the lake settles near the lake bottom and gets trapped there.

Turnover sets the dead matter and toxins free.

As surface water temperatures cool in autumn, the colder water descends, breaking down the thermocline. When this thermal barrier finally goes, the lake turns into a sick soup.

Use your options

Can you catch a few fish after turnover? Sure. But the chances of having a great fall outing are slim.

The best thing you can do during lake turnover is leave! Find another lake to fish.

Turnover can be a trying time for anglers. Your best bet may be to fish a river or a lake that is out of the turnover cycle

Or fish a river! River current constantly circulates water, thus preventing stratification. Get your jon boat or don a pair of waders, and hit the streams.

Here’s some good news. Not every lake turns over at the same time. Depth, water clarity, current, and wind exposure are all factors. If you have multiple waters in your area, odds are that one is hosting a hot bite while another nurses its hangover.

Turnover may last a few days or 10 or more days.

Wind hastens recovery. It assists lake recovery by oxygenating and circulating water.

After turnover passes, fish will have many more options as to where they can live and feed. Bass, for instance, may still be shallow, but they might also use deep structure that was uninhabitable for them during the summer months.

Signs of sickness

Bassmaster Open star Janet Parker worked a deep point with a tube jig for this post-turnover smallmouth. High winds for several days made for a blessedly brief turnover period on this Brainerd, MN-area lake.

How do you recognize a lake undergoing turnover? If your generally clear or at least healthy looking lake looks like it woke up with a bad hangover and needs some clean-up attention, it’s probably turnover time.

Dissolved oxygen levels are compromised, and the fish likely feel as bad as the lake looks.

In most cases, turnover doesn’t kill a lot of fish, but it usually knocks them for a loop for awhile.

Not all lakes experience turnover, but many do. And, contrary to popular opinion,  small waters will turn over. In fact, small waters can experience several turnovers in the course of a season.



Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.