Water Quality of the Markanda and Ghaggar River: A Comprehensive Study of Drain Water Impact

ABSTRACT The river pollution in fast‐growing cities with untreated municipal sewage, industrial effluents, and agricultural run‐offs threatens rivers in agriculturally intensive areas. This study investigated the pre‐monsoon water quality and water quality index (WQI) of Markanda and Ghaggar rivers, focusing on the physico‐chemical analysis and the environmental impact of drain water mixing into the river. Samples of water were drawn from upstream and downstream, and from points where drains were mixed into the river. The findings indicate severe water degradation in the drains and downstream areas. High biological oxygen demand (BOD) (190 mg/L) and chemical oxygen demand (COD) (640 mg/L) indicate very high loads of organic pollution. Increased total dissolved solids (TDS) (3682 mg/L) and total suspended solids (TSS) indicate higher salinity, which is less suitable for irrigation and drinking purposes. The nutrient levels, elevated with NH 4 + ‐N reaching 15.48 mg/L and phosphate reaching 6.48 mg/L, pose a risk of eutrophication and toxicity to aquatic organisms. The chloride levels also exceeded the permissible limit, indicating anthropogenic effects. The upstream water quality ranged from fair to excellent, with physico‐chemical parameters within acceptable limits for aquatic life and agricultural use. The downstream values of WQI ranged from poor to very poor after the drain water mixing. The Gibbs diagram used to perform hydrochemical analysis indicates that the anthropogenic activity is the leading contributor to the control of water chemistry and not the natural geochemical processes. The study concludes that the drain water has a negative effect on the river's ecosystem and poses risks to aquatic life and agricultural productivity, underscoring the need for improved river pollution management.