Presented bachelor thesis includes theoretical knowledge of surface waters, negative impacts of anthropogenic activity on their state, requirements for their quality, system of its assessment in Slovakia and gives an overview of valid legislation in the area of surface waters. The aim of the work was to process the research of surface water problems and to assess the impact of anthropogenic activity on the quality of surface waters in the section of the Váh river in the vicinity of city Ružomberok by setting selected physico-chemical indicators and ecotoxicological tests. On the basis of the results obtained, it was found that from the seven sampling sites the chemical oxygen demand was exceeded in the section under the former textile factory Texicom and sewage treatment plant (sampling sites 5-7), indicating pollution by organic substances. Evidence of pollution is also the result of the Daphnia magna immobilization test, which was positive (sampling sites 5-6). However, the Lemna minor acute toxicity test was negative. Pollution was probably caused by tributaries of the river Váh with un-drained villages and also from older loads of textile factory that is no longer in operation.