10. Spatio-temporal Changes in Pollution Status of the Haora River

A detailed survey has been carried out in order to assess the pollution status of the Haora River at different critical points and in different time periods (2004–2013). All the 15 parameters of the ten selected water samples are categorised into three heads for analysing the pollution status in details. Among physical components of the water quality, total suspended solid and total dissolved solid are very much fluctuating throughout the entire stretch. There is a gradual increase in the total suspended solid towards the lower catchment of the river. But the temporal fluctuation within the period of 2004–2013 is very high. Trace of all the chemical minerals is high in the lower catchment of the Haora River as major concentration of industries and slum clusters are located within this region. In the case of biological components, dissolved oxygen is decreasing towards the downstream part of the Haora River. Both BOD and COD rates are increasing at the lower catchment. The rate of total coliform is increasing in an alarming rate both spatial and temporal levels. The disposal of huge amount of excreta directly into the river from the slum areas is the main cause behind the high concentration of coliform in water.