Surface water is the water found in lakes, rivers, seas, and wetlands. Eutrophication occurs when an excess of nutrients, such as phosphorus and nitrogen, enters the soil and water. This leads to increased algae growth in lakes and seas, resulting in higher water turbidity and further algal blooms. As these organisms decompose, they can cause oxygen depletion in the water. Eutrophication primarily affects water bodies located in densely populated or agricultural areas.