Which substance is found in the highest weight in US streams and rivers?

The substance found in the highest weight in U.S. streams and rivers is soil from erosion. Soil erosion is a natural process, but human activities such as agriculture, deforestation, and urban development can significantly increase the amount of soil that enters waterways. When soil is eroded, it often gets carried into streams and rivers, where it can create sediment pollution. This sediment can have various effects on aquatic ecosystems, including blocking sunlight, disrupting habitats, and affecting water quality.

The weight of this sediment often surpasses that of other substances, as it can accumulate over large areas and consist of considerable quantities of soil particles that are washed away during rainfall or through other means. In contrast, while plastic waste, phosphates, and algae contribute to pollution in aquatic systems, they do not typically reach the same levels of mass as eroded soil in flowing water bodies; therefore, soil erosion remains the predominant issue regarding weight in the context of streams and rivers.