When may eutrophication of a lake occur?

Answer 1

Eutrophication of a lake may occur when the lake acquires a high concentration of nutrients, especially phosphates and nitrates. This may occur naturally, or it may be caused by human activity such as fertilizers or sewage runoff. The high concentration of nutrients typically promotes excessive growth of algae. As the algae die and decompose, high levels of organic matter and the decomposing organisms deplete the water of available oxygen, causing the death of other organisms, like fish.