Advances in Water Resource and Protection (AWRP) Volume 1 Issue 3, July 2013 www.seipub.org/awrp 39 Assessment of Indicator Parameters to Investigate the Seasonal Variation in Groundwater Quality of Chandrapur, Maharashtra, India Prashant N. Rajankar* 1 , Dilip H. Tambekar 2 , Satish R. Wate 3 * 1,3 Environmental Impact & Risk Assessment Division, National Environmental Engineering Research Institute (NEERI), Nagpur-440020, India *1 Current Address –Senior Programme Officer, Toxics Link, H-2, G/Fr, Jungpura Ext. New Delhi-110014 2 P.G. Department of Microbiology, SGB Amravati University, Amravati-444602, India *1 prashantrajankar@gmail.com; 2 diliptambekar@rediffmail.com; 3 sr_wate@neeri.res.in Abstract Groundwater quality of Chandrapur district was assessed in pre and post monsoon season based on the physicochemical parameters, biological parameters and water quality index. The water quality index was calculated using indicator parameters viz., pH, turbidity, temperature, nitrates, total phosphate, dissolved oxygen, biochemical oxygen demand, total solids, faecal coliforms with respect to its different uses like residential and commercial, as well as indicator parameters, in addition, index value was compared with quality rating to examine the seasonal variation in groundwater quality. The water quality index was observed from 74.0 to 83.0 and 63.0 to 78.0 in pre and post monsoon season, respectively. Our finding indicates that 100 percent (70 samples) groundwater samples were of desirable quality in pre monsoon season but 30 percent (21 samples) of all showed the quality change from well to less fair in post monsoon season, this seasonal variation in water quality rating has indicated the deterioration of water quality in the study area, thus indicating a need of proper treatment before use. Keyword Groundwater; Water Quality Index; Seasonal Variation; Physico- chemical Parameters; National Sanitation Foundation (NSF) Introduction Groundwater represents an important source of safe drinking water because surface water does not possess certain properties, but currently its quality is threatened by a combination of over-abstraction, microbiological and chemical contamination (Pedley and Howard 1997 and Reid et. al, 2003). The groundwater quality is a function of natural processes as well as anthropogenic activities. The safe potable water is enormously essential for living and groundwater is one of the sources for human consumption in both urban as well as rural areas. In India more than 80 percent of the rural population depends on untreated groundwater for potable water supplies (Sudhakar and Mamatha, 2004). The groundwater resources are at higher risk as its remediation is very difficult (Rajankar, et. al, 2010). In addition, the problem of drinking water contamination, water conservation and water quality management has tied much importance with sustainable development of countries, such as India. The major anthropogenic activities for continuous groundwater quality deterioration are urbanization, industrialization, and agriculture run off. A study conducted by Central Ground Water Board in 2009 indicated that the groundwater quality was good and suitable for drinking and irrigation purpose, however, localized nitrate and fluoride contamination have been observed (GCWB, 2009). In the present study, the groundwater quality of Chandrapur district was studied by using biological and physico-chemical parameters, further Water Quality Index (WQI) was calculated using indicator parameters. This is first time that the WQI has been applied to groundwater of Chandrapur district. Determination of water quality is very important for the suitability of water for various purposes. Use of WQI to determine the water quality of aqua resources is considered as one of the most effective tool to compare water resources (Sinha and Shrivastava, 1994; Pradhan et al., 2001). The WQI was developed in the