Determination of water quality in the Köprüçay river (Antalya-Türkiye) using various epilithic diatom and water quality indices

This study, carried out seasonally between October-2019 and July-2020, aimed to determine the water quality using some water and epilithic diatom indices of the Köprüçay River. It is located in the south of Türkiye and used for tourism, irrigation and drinking water. Ammonium nitrogen (NH₄–N), nitrate nitrogen (NO₃–N), sulfate (SO₄⁻²), bicarbonate (HCO₃⁻), orthophosphate (PO₄–P), chloride (Cl⁻), biochemical oxygen demand (BOD₅), temperature (°C), dissolved oxygen, pH, and electrical conductivity were measured. Water quality was determined according to the Surface Water Quality Regulation (SWQR) and Water Quality Index (WQI). The water quality classes of the stream, based on epilithic diatom assemblages, were determined using the Generic Diatom Index (GDI), Saprobi Index (SI), Trophic Index (TI), Swiss Diatom Index (DI-CH), and Trophic Diatom Index (TDI). According to SWQR, the average values of the parameters at all sites were generally in the class I or II (high quality or lightly polluted water). WQI, was calculated based on seasonal and site and all results were determined as “excellent water”. 117 taxa belonging to 51 genera of epilithic diatoms were observed in the Köprüçay River. According to epilithic diatoms, generally all sites were in the range of very slightly polluted or partially polluted (I and II) water quality classes.