Attached to soil particles often comes nutrients such as Phosphates, Nitrogen and Ammonia, which have been spread on nearby fields as fertiliser or as waste disposal. Excessive nutrients change the ecology of rivers making them eutrophic (enriched) and are one of the important ingredients in algal blooms.
Algal blooms disrupt the balance of aquatic ecosystems and reduce biodiversity. They can reduce the levels of oxygen in the water, threatening fish and other organisms. Prolonged blooms can also have economic consequences with tourism businesses based on otherwise clean rivers experiencing reduced income.
High levels of ammonia also have severe impact on aquatic life, including fish, crustaceans, and insects.