The Yalvaç Stream is one of the important sources feeding Lake Eğirdir, the second largest freshwater lake in Turkey. Determining the pollution of the stream used for drinking water and agricultural irrigation is important not only for the continuation of the usability of water, but also for determining the pollution load it carries to Lake Eğirdir. In addition, the macrozoobenthic invertebrate fauna of the stream was revealed in the study. The study was carried out between April 2022 and January 2023, and water and macrozoobenthic invertebrate samples were taken from six stations seasonally. Belgian Biotic Index, BMWP (original and Spanish versions), and species diversity indices were applied for determining the water quality by using the ASTERICS software program. Physicochemical water quality assessment made according to the Türkiye Surface Water Quality Regulation. As a result, a total of 49 taxa were detected: three taxa from Gastropoda, two taxa from Hirudinea, one taxon from Malacostraca, and 43 taxa from Insecta. Stations were clustered by using UPGMA based on organisms. Station 6 was the most different one for the macrozoobenthic invertebrates. The lowest species diversity values were also found at this station. Physicochemical parameters and biotic indices showed that while the first three stations were in water quality class I, there was a decrease in the water quality of the other stations. The reasons for the decrease in water quality are due to domestic and agricultural wastes and livestock activities. Additionally, all of the identified taxa were reported as new records for this stream.