Lake Turnover Phenomenon

Lake turnover is the process of a lake’s water turning over from top (epilimnion) to bottom (hypolimnion). During the summer, the epilimnion, or surface layer, is the warmest. It is heated by the sun. The deepest layer, the hypolimnion, is the coldest.

When the surface water begins to cool it becomes more dense, causing it to sink. This dense water forces the water of the hypolimnion to rise, “turning over” the layers.

Here’s a simple definition: Turnover is the period of time when the lake is circulating from top to bottom and the water temperature is uniform throughout.

When the turnover is in progress:

The entire water column will be at the same temperature, give or take a degree or two.
Sudden decrease in water clarity. Water circulation puts particles into suspension, so the water often looks “dirty” during turnover. Clumps of decaying organic matter on the surface. The circulating action of the turnover causes material to break loose from the bottom. Sometimes you’ll see large mats of brownish glop floating everywhere.

So Larry Kovar (Aquatic Annalists) did some testing on the lake as sent in report and not much difference in temperature from top to bottom. Would support above . The surface temperature of our lake was 87 then went to 75 with the rain and cooler temperature. The now cooler dense water then sinks to the bottom and bottom water comes to top along with a lot of sediment. There is not much algae in the water. Many lakes around the are are experiencing this with in the past two weeks.