Considering the risks of water contamination by anthropic activities in general, objectified aimed to analyze the impacts of activities installed in the contribution basin of one of the main springs of Lajeado Erval Novo, rural area of the municipality of Bom Progresso/RS. Bordering the source, after the riparian forest, there is agricultural occupation with management of annual crops.. Far 280 m upstream from the source operates a landfill. The evaluation of contamination by micro pollutants was performed through the analysis of physical, chemical and microbiological indicators, as well as the search for pesticides. Four analytical campaigns were conducted during 2018, with sampling in January, April, July and October. Among the findings of the study it is noteworthy that the landfill has negligible potential for contamination to spring water and that no characteristic elements of landfill leachate were found. The high concentration of aluminum and the slightly acidic pH of the waters may be of natural origin. Sulphate and nitrate contents, as well as the high total and thermotolerant coliforms count may indicate agricultural contamination. No pesticide molecules were quantified. It was also concluded by the classification of the source as Class 3.