77-Water quality and trophic status of Sagar Lake for its restoration

Abstract

The Sagar lake is situated in the heart of the Sagar city of Madhya Pradesh which falls in the Vindhyan terrain of Bundelkhand region. The quality of lake water has poorly deteriorated and has become unsuitable for various uses. In the present study, physico- chemical analysis has been carried out to assess the present status of water quality and trophic status of the lake. Water samples were collected from twenty one locations of the lake at three different depths and six major nallas. The study indicates that the transparency, pH, and dissolved oxygen (DO) contents of the lake water have significantly reduced while the alkalinity, nitrate, phosphate and iron level of the lake water have greatly increased over the past eighteen years. The lake water also contains the fecal coliform bacteria and high algae activity. Results of the present study are compared with 1990 data as well as Indian Standards. The six major nallas have been identified as the point sources of major pollution to the lake. The trophic state index (TSI) has been computed on the basis of nitrate, phosphate and Secchi depth to assess the eutrophication of the Sagar lake. The increased level of nitrogen and phosphorous contents and reduced Secchi depth indicate that the lake has attained the hyper-eutrophic state. Based on the TSI value, the lake has become unsuitable for drinking, bathing and even for fish culture.