Water quality and sediment characteristics of the Batang Baleh and its tributaries were studied to see how human activities affect them. The researchers found that areas near logging had higher levels of pollutants in the water and sediment. Stations near longhouses also had higher levels of certain pollutants. During the wet season, the downstream area had lower water quality. Some sediment may harm benthic organisms. Overall, most stations were slightly polluted, with one being classified as polluted.