The aim of the study was to assess the content of soluble forms of fertilizer nutrients (N, P, K) in the cultivated soil layer up to 20 cm deep from agricultural land in the river valley, and the concentration of these nutrients in the surface waters of the Raszynka River. In the years 2016–2017, the surface water samples from the Raszynka Rriver (17 points) and soil (19 points) were collected from agricultural areas near the Raszynka River. The surface water samples were collected once a month during the March–October 2016–2017. The contents of nitrogen (Ntot, NO3-N and NH4-N), phosphorus (Ptot, PO4-P), total organic carbon (TOC and K and Ca) in soils and in waters were determined in the sample solutions. It was shown that river water was of low quality due to the high concentration of nitrogen and phosphorus and electrical conductivity (EC). The most polluted were the waters of the lower section of the river located in the vicinity of arable land and agricultural built-up areas. The soluble forms of nutrients content in the cultivated soil layer was varied depending on the kind of nutrient, way of agricultural land use, and the term of soil sampling. The content of dissolved P forms in the soil was the highest in autumn on arable lands after harvesting of vegetables (GO-W: 10.24 mg Ptot·kg−1 in D.M.) and this component may migrate with surface runoff and increase the risk of surface water eutrophication.