Evaluation of Water Quality of Magadi Wetland in Gadag District, Karnataka

Wetlands are probably the earth’s most important freshwater resource and are also the most threatened. They have intrinsic ecological and environmental values. They are fragile ecosystems that are susceptible to damage even with only a little change in biotic and abiotic factors. They are threatened due to inadequate water holding capacity, excessive withdrawal, pollution due to sewage and sullage, eutrophication, leached fertilizers and insecticides. Magadi wetland area in Gadag district of Karnataka state supports agriculture and fishing etc. This tank supports a large population of migratory waterfowl especially during winter. In fact it is one of the largest wintering grounds for the Bar-headed geese (Anser indicus) in South India. The tank is also facing degradation by the aforementioned threats. The degradation in the water quality affects the floral and faunal population along with the people dependent on this ecosystem. A reconnanaissance survey of the wetland was done in the year 2006 to assess the geohydrological characteristics of the wetland, the factors which influence water quality in the basin, the land use activities, status of community health, urban and rural settlements etc. Based on reconnaissance survey, various water quality stations were identified in the wetland area, up steam, in and down stream. The water quality of Magadi wetland revealed that, the tank was polluted due to the inflow of effluents from the neighboring areas contributing to alkaline pH, high EC, high total solids, low dissolved oxygen and high nitrate and phosphates. The water is not used for irrigation because of a high concentration of dissolved solids. The sources of effluents are in the form of runoff from agricultural activities in the catchment’s area, human activities like bathing and washing etc. There is an urgent need for scientific management of the wetland.