What is the Effect of fertilizers when they are washed into rivers?

When fertilizers are washed into rivers, they can cause nutrient pollution, primarily from nitrogen and phosphorus. This leads to algal blooms, which deplete oxygen levels in the water and can create dead zones where aquatic life cannot survive. The resulting ecosystem imbalance can harm fish populations and other aquatic organisms, disrupt food webs, and degrade water quality, impacting both wildlife and human health. Additionally, harmful algal blooms can produce toxins that pose risks to drinking water sources and recreational activities.