The aim of this paper was to evaluate the influence of anthropogenic pollution on the water quality of the Ciemięga River, which flows through the Jastków commune, located in the Lublin Province in the South-Eastern Poland. The analyses of the river water were conducted in the years 2019–2020. Each year, the samples for physicochemical analyses were collected seasonally (in February, May, August and November) from the seven selected Ciemięga River sampling points found in the following localities: Ożarów, Moszenki, Sieprawice, Jastków, Snopków and Jakubowice Konińskie. In addition, 3 series of microbiological analysis were conducted in 2020. Electrolytic conductivity, total phosphorus, nitrate-nitrogen and sulfates constituted the physicochemical indicators of poor water quality in the river. Their average values exceeded the standards for the 2nd class of water quality. High concentration of these indicators, especially of the total phosphorus, could have been related to the influx of domestic wastewater from agricultural holdings, wastewater flows from agricultural areas as well as soil erosion and leaching. The levels of E. coli bacteria and fecal coliform allocated the Ciemięga River waters to the 4th class of water quality and could result from domestic wastewater flow to the river. In order to improve the water quality of the Ciemięga River, it is necessary to reduce or eliminate point and non-point sources of pollution by means of streamlining of the agricultural areas fertilization, regulating the water and wastewater management, regulating of the waste management, as well as the appropriate spatial policy and landscaping of the water catchment areas.