Introduction

Lakes and ponds cover only a very small portion of increased understanding of the drinking water quality to public health and raw water quality to aquatic life, there is a great need to assess surface water quality (Ouyang 2003). It gets affected through various factors mainly by anthropogenic activities. Freshwater ecosystems are getting deteriorated because of the developmental activities and highest degradation are caused by humans and their related activities in their immediate catchment areas and drainage basins (Rast 2009, Mishra and Garg 2011, Amin et al. 2014).Increases in impermeable surfaces, as well as vehicular traffic related to the flow of people and material in the growing regional economy can increase pollution loads and runoff to urban and increase pollution loads and runoff to urban and periruban water bodies (Lebel 2009). Water quality deterioration in lakes has recently been a matter of great concern due to its negative impacts on social economic and health aspects and has been recognized as a serious problem at local regional and global levels. Due to population growth and industrial development, numerous water bodies have become heavily polluted over past several years. The major problem with the lake is implemented by rainy water or other feeding sources that once contaminated, it is defaulted restore its quality (Dubey 2016).

Water quality is the characteristics of water which influence its beneficial use as well as the sustainability of ecosystem. The quality of water in any ecosystem provides significant information about the available resources for supporting life in that ecosystem and the suitability for human use (Lianthuamluaia et al. 2013). The quality of surface water is governed by the natural and anthropogenic processes including rainfall, erosion, hydrological features, industrial and agricultural activities (Bhat and Pandit 2014). The quality of water in lakes, reservoirs, rivers are determined by physico-chemical and biological parameters. Water quality index provides overall water quality at a certain location and time based on multiple water quality parameters. Water quality monitoring is one of the key tools, to identify and keep a check on the pollution status and ensure about the efficiency of management plans (Singh and Jayakumar 2016). Hence monitoring of these aquatic resources is crucial for sustainable management.

Bangalore and its urban conglomerates comprise of many man-made wetlands that were built for various hydrological purposes to serve the needs and water demand of the city. Bangalore wetlands have been experiencing anthropogenic stress especially due to the sustained inflow of sewage altering the chemical integrity of wetlands. The present study was carried out to evaluate seasonal variation in the physico-chemical parameters of water quality and to compute water quality index (WQI) of Hebbal Lake, Bangalore.