The "Spring Clear-Water Phase": Why Your Pristine Lake Turns Cloudy Every Summer

Summary:Many lake owners notice a "magic" window in late spring where the water is incredibly clear, only to see it turn murky by July. This isn't random; it’s a biological cycle called the "Clear-Water Phase." In spring, tiny organisms called daphnia (water fleas) go on a feeding frenzy, eating up all the algae. But as the water warms, fish begin to eat the daphnia, and the algae—now unchecked and fueled by summer sun—proliferates, turning your clear water cloudy

The Science Behind It: This transition is driven by a shift in the lake’s trophic cascade. During the spring, large-bodied cladocerans, specifically Daphnia, emerge in massive numbers. Research indicates these grazers can filter the entire volume of a lake's surface layer in days, consuming phytoplankton and creating high transparency. However, this is temporary. As water temperatures rise into the 70s (°F), "young-of-the-year" fish (fry) hatch and begin intensive predation on the daphnia. With their primary predators gone, phytoplankton populations—specifically cyanobacteria and green algae—undergo a "bloom." Furthermore, summer thermal stratification traps nutrients in the warm upper layer (epilimnion), providing a constant food source for these microscopic plants. Studies show that this cloudy July water is actually a sign of a highly productive, albeit less "clear," summer ecosystem.

Article Link:

https://www.google.com/search?q=https://www.nature.com/scitable/knowledge/library/traps-and-subsidies-the-role-of-top-13234932/

6th Feb 2026 Weeders Digest

#lake and pond science

The "Spring Clear-Water Phase": Why Your Pristine Lake Turns Cloudy Every Summer