Evaluation of Pasikhan River, north of Iran using water quality index (NSFWQI)

Water quality indices are among the current techniques for monitoring rivers. Among the general indices of water quality, applying the national sanitation foundation water quality index (NSFWQI) results in precise research outcomes in a short period. Moreover, it enables the classification of river water quality of different stations with a simple expression. The present study, through applying NSFWQI as a water quality index, aimed at determining the water quality of Pasikhan River, located in the north of Guilan Province, Iran. Six sampling stations were set up along the river mainstream, and water samples were collected from these stations during 4 seasons (from autumn 2015 to summer 2016). Nine parameters including water temperature, turbidity, fecal coliform, NO3-, TS, PO43-, pH, DO, and BOD were measured through standard methods. Based on the results, the quality of the river’s water was categorized in the medium and bad classes in all sampling stations for all seasons. Moreover, the results showed that during the sampling seasons, the minimum average of NSFWQI was 52.00 ± 3.94 in the 4th station, while the maximum was 59.50 ± 1.50 in the 3rd station. However, both of them were in the category of medium quality. In general, the water quality values of the stations varied from 46 to 70 in different seasons. According to the results, the Pasikhan River’s water quality is ranked in the category of medium quality.