In ecological terms, waters of the Ob River basin are assessed as “dirty”. The lack of open regional databases of pollution sources hinders identifying the most man-impacted areas there for a detailed study. The author describes a methodological approach to creating small-scale maps of anthropogenic loads on water bodies based on the available internet data. By the example of Tomsk Oblast, RF, we present a step-by-step algorithm for compiling an evaluation map of river basins and their sections: from preparation of the cartographic base and an inventory of potential water pollution sources up to visualization of the region`s territory with estimated indicators. The mapped enterprises influence the water bodies directly or indirectly. Types of settlements and transport networks are analyzed. The mapping was carried out using GIS, with creating of an inventory map, followed by a resulting evaluation one demonstrating the differentiation of river basins/areas of Tomsk Oblast due to the frequency coefficient of potential water pollution sources and their diversity, as well as sites with the highest concentration of enterprises and the transport network that require further detailed study in order to develop recommendations for reducing anthropogenic impacts