Here’s an excerpt from a Boston Globe article about Walden Pond (bold added for emphasis).
As the climate changes, the water is expected to get warmer, which will favor algae that make the water murkier. The warmth also helps more phosphorus, a key nutrient for the algae, escape from the sediment at the bottom, he said.
“Phosphorus is a fertilizer. You put it on a crop, the crop grows better. . . . You put it in a lake, the algae grow better,” he said.
The other problem with the warmer temperatures is that it will lure more people seeking relief from the heat to the pond, “and a certain percentage of them pee,” he said. Previous studies have found that half the phosphorus in the lake in the summer comes from human urine.
Is there any reason to suspect that this wouldn’t be just as true at Crystal Lake?