Agricultural runoff significantly impacts freshwater ecosystems by introducing excess nutrients, particularly nitrogen and phosphorus, into water bodies. This nutrient overload leads to eutrophication, where algal blooms proliferate, consuming available oxygen and harming aquatic life. The resulting hypoxia creates "dead zones," where fish and other organisms cannot survive. Additionally, harmful pesticides and chemicals deplete water quality, disrupting food chains and biodiversity. Effective management practices are essential to mitigate these negative effects on freshwater ecosystems.