The Impact of Mining Activities on River Water Pollution: A Case Study in the Mahakam Watershed

This study investigates the impact of mining activities on river water pollution in the Mahakam Watershed, East Kalimantan, Indonesia. Using a quantitative case study approach, water samples were collected from five strategically selected sites representing upstream, midstream, and downstream areas, with varying degrees of proximity to coal mining operations. The physicochemical analysis revealed elevated concentrations of total suspended solids (TSS), biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), and heavy metals such as iron (Fe), manganese (Mn), and lead (Pb), especially in midstream and downstream sites. These findings suggest that mining runoff and acid mine drainage (AMD) have significantly altered water chemistry. Biological assessments further confirmed ecological stress, as evidenced by the dominance of pollution-tolerant species and a decline in biodiversity. GIS-based spatial analysis identified pollution hotspots near steep, deforested mining zones. Community interviews revealed adverse socio-economic impacts, including reduced fish populations and waterborne health issues. The results highlight the urgent need for integrated watershed management, environmental regulation enforcement, and community-based ecological monitoring to protect the Mahakam River ecosystem and its dependent communities.