Turnover You might know about lake turnover - but just in case, here's a quick review. Differences in the temperature of lake water keep the water column from mixing for most of the year. In the summer, the warm, oxygenated water floats on top of cold, dense, and anoxic water. The lack of oxygen in the deep water allows nutrients and other compounds to dissolve in that water. At some point in the spring and fall, the temperature will be the same throughout the lake from top to bottom, which allows the lake water to mix, called turnover. Waters carrying oxygen, nutrients, and sediment mingle. This mixing turns the lake water murky, and algae can take advantage of all the nutrients that are carried up into the light.