How would sewage lead to eutrophication?

Sewage often contains high levels of nutrients, particularly nitrogen and phosphorus, which are essential for plant growth. When this nutrient-rich sewage is discharged into water bodies, it promotes excessive algal blooms, a process known as eutrophication. As the algae die and decompose, the decomposition process depletes oxygen in the water, leading to hypoxic conditions that can harm aquatic life. This cycle disrupts ecosystems and can result in dead zones where few organisms can survive.