Water Quality Assessment of the Garan dam reservoir (Marivan) using NSFWQI qualitative index

Continuous quality monitoring of water resources are important tools to manage and protect these valuable resources. Kurdistan province is one of the most important provinces in Iran in terms of surface and underground waters, and the Garan reservoir (Marivan) has important rules in drinking water supply, agricultural and industrial activities. For this purpose, 9 water physicochemical and microbial characteristics were studied to determine water quality using NSFWQI index at four sites of Garan reservoir from July 2017 to August 2018. Results showed that the average temperature of water was 11.13 ± 6.7 °C and the Dissolved Oxygen (DO) concentration was 8.44 and 3.87 mg/l for surface and deep layers respectively. Also the annual mean value of Nitrate, Phosphate, Biochemical Oxygen Demand (BOD5), Total Solids (TS) and pH were 0.66, 0.052, 1.32, 156.91 mg/l and 7.99 respectively. The mean of fecal coliform was 20.15 MPN so that the minimum of value was seen in October (0.25 MPN) and maximum of value was observed in March (208 MPN). As well as Lake Water had good quality according to NSFWQI index value (70.72). In general, although temporal and spatial variations were observed in some of the measured parameters, but based on the results of the physico-chemical characteristics and NSFWQI index, the Garan reservoir is categorized in having middle to good levels therefore, it was evaluated as desirable for agricultural, industrial activities and even drinking water after regular treatment.