Temporal analysis of the Hooghly River's water quality: investigating pre- and post-monsoon scenarios in West Bengal, India

This research aimed to investigate the influence of ferry operations and religious activities on the water quality of the Hooghly River in Kolkata, West Bengal, during 2022, while pinpointing pollution hotspots and suggesting mitigation strategies. As a crucial distributary, the Hooghly River is significantly impacted by human activities, particularly near ferry terminals and pilgrimage locations. Water samples (4 L) were taken from eight critical sites during pre- and post-monsoon periods at high tide, concentrating on important physico-chemical and biological attributes. Though pre-monsoon water quality largely adhered to BIS guidelines, heightened chemical oxygen demand and total coliform (TC) levels indicated potential pollution hotspots, likely caused by ferry movements and religious gatherings. Post-monsoon data revealed acceptable pH and temperature ranges but flagged concerns due to increased biochemical oxygen demand and TC counts, especially in high-traffic zones. The water quality index varied between 213 and 282, with a higher pre-monsoon value of 282 and a post-monsoon value of 213, primarily influenced by total dissolved solids, hardness, alkalinity, and conductivity. The comprehensive pollution index ranged from 1.30 to 1.33, surpassing the acceptable limit. These assessments reveal the impact of ferry and religious activities on the Hooghly River's water quality, stressing the need for targeted pollution control.