Nutrient runoff occurs when excess nutrients, primarily nitrogen and phosphorus, wash away from agricultural fields into nearby water bodies. This often happens after heavy rainfall or irrigation, leading to the leaching of fertilizers and animal waste into rivers, lakes, and oceans. This runoff can cause water pollution, resulting in harmful algal blooms that deplete oxygen levels and harm aquatic life. The process can disrupt ecosystems and affect drinking water quality, making it a significant environmental concern for communities and wildlife alike.