How do factory farms pollute rivers?

Factory farms pollute rivers primarily through runoff that contains excessive nutrients, such as nitrogen and phosphorus, from animal waste and feed. This runoff can lead to eutrophication, causing harmful algal blooms that deplete oxygen in the water and harm aquatic life. Additionally, pathogens and chemicals from these farms can contaminate water sources, posing risks to both ecosystems and human health. The concentration of waste from large numbers of animals amplifies these environmental impacts significantly.