Every autumn, as air temperatures drop, lakes undergo a process called turnover, which helps oxygen circulate and prevents stagnation. During the summer, warm water sits at the surface while colder, denser water remains at the bottom. But when fall arrives, surface water cools, becomes heavier, and sinks, forcing deeper water upward. This mixing of water layers is essential for aquatic life, bringing oxygen to deeper areas and redistributing nutrients. Fishermen often notice turnover because it temporarily disrupts fish patterns, making them harder to locate. After a few weeks, however, fish settle into their cold weather habits, and the lakes stabilize for winter.