Mojgan Mirzaei - School of Natural Resources and Environment, Malayer University, Malayer, Hamedan, Iran
Eisa Solgi - Department of Environment, School of Natural Resources and Environment, Malayer University, Malayer, Hamedan, Iran
Abdollrasoul Salman-Mahiny - Department of Environment, School of Fisheries and Environmental Sciences, Gorgan University of Agriculture Sciences andNatural Resources, Gorgan, Iran

Background & Aims of the Study: Water resources are useful or potentially useful. Uses ofwater are included agricultural, industrial, household, recreational and environmentalactivities. The majority of human uses require fresh water. Rivers are parts of this freshwater that play a very important role in the water cycle, acting as drainage channels forsurface water. Hence, regular monitoring program and water quality control are the mostimportant strategies to reduce pollution and improve the quality of water. The aim of thisstudy is the evaluation of surface water quality by NSFWQI index and pollution riskassessment, using WRASTIC index in 2015.Materials and Methods: In this study, the analytical survey, experimental studies andinvestigation of references in the context of library studies have been used. Water qualitydata collected from 7 sampling sites during 4 seasons from March to February 2015 andquality parameters including dissolved oxygen, pH, total dissolved solids, biochemicaloxygen demand, turbidity, temperature, phosphate, nitrate and fecal coliform wereexamined by standard method. Data were analyzed by National Sanitation FoundationWater Quality Index. Then WRASTIC index (Wastewater-Recreational-Agricultural-Size-Transportations avenues- Industrial -cover of vegetation) is used for risk assessment inbasin.Results: NSFWQI index results showed that water quality in the river station 1 (Morkan) islocated in the middle class and other stations in all seasons have bad quality. The worstsituation (bad quality) was related to the bridge Chum and Varzaneh in autumn with anaverage of 29 and the best quality is relevant to Morkan station in summer with an averageof 59. The finding of WRASTIC index represent that watershed is located in high risk classwith the value of 70.Conclusion: Based on the results of this study, the pollution from station 1 toward thesubsequent stations have increased significantly and the river water quality has beenreduced. In addition, agricultural, industrial activities and population centers are the maincauses of Zayandehrud river pollution. Therefore, the management plans to protect of thisvaluable river is necessary.

Human ActivitiesRisk AssessmentPollutionWater QualityZayandehrud riverIran