Surface water is subject to strong anthropogenic pressures caused by the development and the extension of the agricultural activities and also by the industrial and domestic activities. Pollution is a major environmental problem due to discharges into rivers and the excessive use of agricultural fertilizers add to that the discharges from urban and industrial sources. The aim of this study is to assess the quality and the state of the organic pollution of surface water in the Kébir wadi east, based on the Water Quality Index (WQI) and the Organic Pollution Index (OPI) during six sampling campaigns carried out between April and September of the year 2011. Seven stations were studied along the Kébir wadi east downstream from the Mexa Dam. The results are visualized by the use of GIS through making thematic maps. They revealed that half of the stations show excellent to good water quality and moderated organic pollution except the stations S3, S6 and S4, that have poor water quality and high pollution at S3 and S6 respectively, and non-potable water with very high organic pollution at S4. The anthropogenic environmental deterioration recorded in the wadi is the result of the use of nitrogen and phosphate agricultural fertilizers and especially, the discharge of untreated domestic and industrial wastewater from neighbouring agglomerations. The seasonal variation remains discrete and reflects a slight tendency to the deterioration of the waters of El Tarf region during the low waters of the summer period.