4-Importance of First Flush in Restoration of Lake Water Quality - A Case Study of Mansagar Lake.

Abstract

Water quality in lakes is significantly affected by stormwater. After first rains, the lake water quality deteriorates due to washing up of municipal waste from the catchment area. In our country, the management of municipal waste is not very efficient and the initial stormwater generated during rains has a high concentration of organics besides other suspended solids thus having a huge potential for the deterioration of water quality of the lake receiving it. The present paper discusses the negative impact of firstfush on lake water quality with a case study of Mansagar Lake, Jaipur, where exceptionally high values of BOD were found in the flushes after the first few rainfall events. The deterioration of the lake water quality immediately after the first rains in terms of biological quality has been monitored for 5 years and the effects have been reported, which may be applicable to most of the lake catchments in India.