This paper presents the results of research on the impact of the composition of wastewater discharged from a hybrid constructed wetland wastewater treatment plant on the quality of water in the Urzędówka River, a right tributary of the Wyżnica River. During the years 2011-2013, samples of treated wastewater and water from the river were collected (upstream and downstream of the wastewater discharge point) and subjected to physicochemical analysis and, in 2013, also to microbiological analysis. The study showed that the treated wastewater outflowing from the treatment plant did not have any negative influence on the quality of the water in the receiver. Water from the Urzędówka River met clarity standards for class I waters; only the concentrations of total phosphorus and nitrate nitrogen exceeded the limit values for water clarity class II. The studies have shown that waters from the Urzędówka River upstream of the treatment plant contained a huge concentration of E. coli bacteria, fecal coliform bacteria and fecal enterococci, which indicates the impact of other sources of microbiological pollution.