How does rain influence agricultural runoff, nutrient pollution, and eutrophication in rivers, lakes, and coastal watersheds?

Rainfall can contribute to agricultural runoff, nutrient pollution, and eutrophication in rivers, lakes, and coastal watersheds by washing away fertilizers, pesticides, and animal waste from farmland into waterways. Excess nutrients such as nitrogen and phosphorus fuel algal blooms and aquatic plant growth, leading to oxygen depletion, water quality degradation, and ecosystem imbalances that harm aquatic life and human health.