This study compares the levels of heavy metals mercury (Hg), cadmium (Cd), and lead (Pb) in Batak fish (Tor soro), water columns, and sediments of the Asahan River affected by industrial waste. Results indicate that Pb and Cd levels in water remain within quality standards, while heavy metal concentrations in sediments are below environmental risk thresholds.

The flow of the Asahan River passes through the large PLTA Inalum Operating plant, which has the potential to cause pollution due to industrial waste disposal activities. One of the pollutants of concern in the Asahan River is heavy metals such as mercury (Hg), cadmium (Cd), and lead (Pb). Various aquatic biota live in the Asahan River, including Batak fish (Tor soro), an endemic species of North Sumatra. This fish is also commonly consumed by local communities around the Asahan River. The study results showed that the levels of lead (Pb) and cadmium (Cd) in Asahan River water were below the detection limit and still met water quality standards based on Government Regulation of the Republic of Indonesia No. 22 of 2021. The concentration of heavy metals in Asahan River sediments was also found to be below the environmental risk threshold.