Analysis of Water Quality Index (WQI) in Dalvoy Lake, Mysore City, India

The Dalvoy lake of Mysore is fed mostly by storm water drainage from a major part of the city. It is exposed to the influence of heavy urbanization and industrialization. The lake water is primarily used for agricultural practices seen over the southeastern side of the lake at downstream end. Due to several reasons, the water quality is deteriorating. In order to evaluate the potability and assessment of water quality for different purposes, all important physicochemical and biological parameters were detected by collecting samples from the surface and also from depths ranging from 4 to 12 feet. The water analysis data were processed to determine the water quality index by NSF method. For each of WQI a descriptive quality indicator has been derived as very poor (0-38), poor (39-71), good (72-83), very good (84-89) and excellent (90-100) categories. Surface water quality, mainly used for drinking water abstraction, has been represented on the lake network map. In this paper the water quality indicators were calculated for all locations and also classified with reference to seasons. It was observed that the WQI of the Dalvoy lake is not good and the main cause of deterioration is due to the lack of proper sanitation, untreated inflow water with municipal sewage and due to uncontrolled anthropogenic activities.