Qualitative assessment of Bojnurd main water supply by using water quality indices in 2013:Case study of Shirin Dareh reservoir dam

The use of quality indicators to decide on water resources management has been suggested as a strong management tool for decision making. Considering the importance of Shirin Dareh reservoir dam, which supplies a great part of drinking water for Bojnurd this study was conducted to evaluate the water quality and to determine the process of the lake feeding in 2014. This study is a descriptive cross sectional one the sampling occurred in 12 months of 2014 in seven different stations. Quality parameters that were measured include: pH, TS, BOD, DO, nitrate, phosphate, temperature, turbidity and fecal coliforms. Data were analyzed by NSFWQI.According to NSFWQI index, in the studied stations during the year, the highest quality was observed in station No. 4 with the score of 69 and the lowest quality in station No.1 with the score of 65. The highest quality was observed in February and January with the score of 70 and the lowest quality in July with the score of 60.Results of NSFWQI index showed that the available water in ShirinDareh reservoir has higher quality in cold months of the year compared to warm months for supplying the drinking water of the city.