Surface waters in the Lepenc river basin have been under the influence of a large number of contamination factors of anthropogenic nature over the last two decades. Contaminations from the soil surface easily reach surface waters, modifying water quality. Today there are many methods that are used to classify surface water quality. This paper aims to demonstrate the state of surface water quality based on the water quality index (WQI). To investigate the WQI in the Lepenc river basin, data was measured in spring, summer, and autumn of 2017. According to WQI, the waters in the Lepenc river basin, including Nerodime and Lepenc rivers, vary from WQI-36 to WQI-76.

We used physicochemical and biological parameters to evaluate the water quality in river Nerodime in Kosovo. The research was conducted in spring 2017, in three stations along the river (upstream, middle and downstream). River Nerodime is the biggest tributary of the River Lepenci Basin that flows in South Eastern part of Kosovo. During its flow, Nerodime enters the cities of Ferizaj and Kaçaniku where it becomes a collector of many pollutants of diverse origin. Our research concluded that the river conditions are very severe in middle and downstream of the river. The values of physicochemical parameters and biotic indices indicate that the water quality in the upper flow is classified good to moderate, whereas in middle and downflow, due to the discharge of municipal wastewaters, industry and agricultural runoff, the water quality significantly decreases and is poor, respectively bad quality.