It was observed that both treated and high amount of untreated sewage water was entering into the lake. Nutrient availability in Jakkur lake water was high which was evident from the results of physico- chemical analysis, the presence of fully covered varied macrophyte species and algal species. Hence, the light penetration is obstructed and dissolved oxygen (DO) level is depleted in the lake. This led to the death of fishes in lake. Compared to the earlier studies the nutrients (N and P) in the water increased around 5 times. The overall water quality was also found to be bad than earlier.
Fish mortality in Jakkur Lake: Recent episodes of fish mortality in Jakkur lake is due to a sudden and considerable fall in dissolved oxygen (DO) levels resulting in asphyxiation in some locations caused by sustained inflow of large quantum of sewage let into the lake (through illegal diversions by local civil contractors). It is not due to any kind of infection because none of the fishes showed any signs of disease symptoms.