Eutrophication is the naturally occurring ageing process of a water body but it has been accelerated when a water body becomes excessively nutrient and minerals rich due to anthropogenic activities, which induce overly growth of plant and algae e.g., increase of phytoplankton in water body, resulting in oxygen depletion because of bacterial degradation of biomass consumes oxygen. So, the levels of dissolved oxygen are severely reduced. The causal factors are the discharge of sewage and agricultural fertilisers containing nitrate which stimulates disproportionate growth.