Ground water, the main source of water supply in many regions of Iran, is exposed to pollutions resulted from urban wastewater, industrial pollutions and agriculture activities. Therefore the aim of this study is to determine the nitrate pollution level and its origin in Kurdan watershed. Groundwater samples were collected from 30 wells in different land use across the Kurdan watershed. The effects of different land use (rangeland, garden, agriculture and urban) on pollution levels are investigated by statistical analysis. Finally we compare different geostatistical methods and generate spatial distributions map of nitrate pollution based on the best (Kriging method). Nitrate concentration mean varied from 11 to 74 mg/L. Results show that nitrate concentration is more than maximum acceptable concentration in drinking water (i.e. 50 mg/L as nitrate recommended by national standard and WHO guideline value) in some parts of the study area and the analyzed samples around agricultural land use have a high value of nitrate. The main source of pollution is fertilizers applied to cultivated land. Pollution concentration of nitrate is the most in the west of Kurdan watershed, where surface water discharge fertilizers to ground water.
