The present study aims at developing a universal method for the localization of critical source areas (CSAs) of diffuse NO3- pollution in rural catchments with low data availability. Based on existing methods land use, soil, slope, riparian buffer strips and distance to surface waters were identified as the most relevant indicator parameters for diffuse agricultural NO3-pollution. The five parameters are averaged in a GIS-overlay to localize areas with low, medium and high risk of NO3- pollution. A first application of the GIS approach to the Ic catchment in France, shows that identified CSAs are in good agreement with results from river monitoring and numerical modelling. Additionally, the GIS approach showed low sensitivity to single parameters, which makes it robust to varying data availability. As a result, the tested GIS-approach provides a promising, easy-to-use CSA identification concept, applicable for a wide range of rural catchments.