Evaluation of water quality of Kosynthos river in North Greece, using Water Quality Indices

The water quality of Kosynthos river, located in Xanthi Prefecture, Northern Greece, was evaluated using Water Quality Indices (WQIs). A water quantity and quality monitoring program was undertaken from December 2016 to November 2017 on a weekly basis at four stations along the main course of Kosynthos river and its main tributary. Discharge, temperature (T), dissolved oxygen (DO), pH and electrical conductivity (EC) were measured in situ. Moreover, water samples were collected and analyzed for the determination of biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), total phosphorus (TP), and ammonium nitrogen (NH4-N), according to the standard methods. Anions (i.e., SO4-2, Cl-), NO3-N, NO2-N, and cations (i.e., Na+, K+, Mg+2, Ca+2) were determined using ion chromatography. The applied WQIs were the Canadian Council of Ministers of Environment (CCME) WQI, the Oregon WQI, the National Sanitation Foundation (NSF) WQI and the Prati’s Index of Pollution. According to the CCME, NSF and Prati’s WQIs the water quality of Kosynthos river for both monitoring periods was classified in the higher quality classes, while according to the Oregon WQI it was classified in the lowest quality class.