Studies on water quality index of bay of Bengal at Digha, West Bengal, India

The water quality Index basing on physico-chemical parameters of Bay of Bengal at Digha-on-Sea has been assessed for three study stations during January, 2011 and December, 2012. The observations revealed seasonal and topographical variations and the parameters were within permissible range (i.e. pH: 6.97 to 7.95, Total alkalinity: 38.00 mgl⁻¹ to 70.95 mgl⁻¹, Total hardness: 9.83 mgl⁻¹ to 28.28 mgl⁻¹, Chloride, 93.45 mgl⁻¹ to 117.46 mgl⁻¹, BOD 5 days: 1.39 mgl⁻¹ to 30.73 mgl⁻¹. However the WQI ranges between minimum of 52.46, 52.03, 48.05 and maximum of 54.39, 54.70, 54.31 at three study stations respectively. These were rated poor where water quality is adverse and the conditions deviate from desirable levels.