Background: Survey of pollution and evaluation of water quality in rivers with Oregon Water Quality Index (OWQI) and GIS are effective tools for management of the impact of environmental water resources. The information in calculating the WQI of Moradbeik river allowed us to take our tests results and make a scientific conclusion about the quality of water. GIS can be a powerful tool for developing solutions for water resources problems for assessing water quality, determining water availability, preventing flooding, understanding the natural environment, and managing water resources on a local or regional scale. Methods: The WQI of Moradbeik river consists of nine tests: Fecal Coliform (FC), Biochemical Oxygen Demand (BOD5), Nitrates (NO3), Total Phosphate (PO4), pH, temperature, Dissolved Oxygen (DO), turbidity, and Total Solid (TS). Water quality of Moradbeik river was investigated for 12 months. Concentrations of these nine variables were normalized on a scale from 0 to 100 and translated into statements of water quality (excellent, good, regular, fair, and poor). Also this data were analyzed with WQI index, and then river basis on water quality was zoning by GIS. Results: The average of WQI was 61.62, which corresponded to ‘‘medium’’ quality water at the sampling point 1 (best station) and decreased to around 26.41 (bad quality) at sampling point 6. The association between sampling points and water quality indexes was statistically significant (P<0.05). Conclusion: Based on physical, chemical and biological agent monitoring and also with control of water quality indexes of these points, we observed wastewater and other river pollutants.