What Is Lake Turnover?

In this brief article brought to you by Aquatic Restoration, we introduce you to the basics of lake turnover, including how it’s caused and why we should care about it. If you’d rather have lake or pond maintenance professionals come out for an investigation, then call Aquatic Restoration to schedule an appointment today.

Lake turnover 101

Lake turnover is a natural process that happens in many lakes and ponds, especially in temperate regions where the seasons change dramatically. Think of it like shaking up a bottle of salad dressing: the oil and vinegar mix together, but when you let it sit, they separate again. In lakes, the “oil” and “vinegar” are like the warm and cool water layers. During turnover, these layers mix together.

Here's how it works: During the warmer months, the top layer of a lake warms up and becomes less dense than the cooler water at the bottom. The cooler, denser water stays at the bottom, while the warmer, lighter water stays on top. As the weather cools in the fall, the surface water cools and becomes denser, sinking to the bottom. This causes the water from the bottom to mix with the water on top. This process is crucial because it helps to mix nutrients and oxygen throughout the lake.

Why should we care about lake turnover?

Lake turnover is more than just a cool science phenomenon; it has a big impact on the health of aquatic ecosystems. When the layers of water mix, it can stir up everything that’s settled at the bottom, like dead plant material and decomposed fish. This can release harmful substances like hydrogen sulfide and ammonia into the water, which can be toxic to fish and other aquatic life.