Abstract: Land-use change in the East Kolkata Wetlands (EKW) area since the 18th century has led to the degradation of the water quality and a loss of the goods and services it provides. Here we perform an in-depth analysis of water quality with a data bank of 3 decades using dissolved oxygen (DO) as the indicator. The loss of head water feed from the River Hooghly, the gradual siltation of the River Bidyadhari, the rapid urbanization of the city of Kolkata and generation of huge quantum of waste water has degraded the water quality to a great extent as revealed from the gradual lowering of the DO level in the selected water body. The WQI has also decreased simultaneously except during premonsoon 2009 when the super cyclone Aila hit the study area and deviate the values of DO and WQI from the normal trend.

Keywords: East Kolkata Wetlands (EKW), Dissolved Oxygen (DO), Water Quality Index (WQI).