Water Quality Evaluation Using Various Water Quality Indices: A Case Study for B. Menderes River, Turkey

Water quality is an important factor for public health and aquatic life, and it has become an increasingly important problem due to the growth of the population, urban expansion, and development. For this reason, the evaluation of surface water quality is an important issue for countries. Water quality indexing is widely used to present complex water quality data in a more comprehensible form and provides decision-makers and non-technical managers of water resources with concise information about water quality status. In this study, the water quality is determined based on the water quality monitoring data obtained from the Kocarli Bridge gauging station in the B. Menderes River for the 9 years period between 2006 and 2014. The main pollutants in this region, with parameters exceeding border limit values PH were found to be Sulphate (SO4), Nitrate (NO3), Ammonia (NH4), Nitrite (NO2), Phosphate (PO4), Electrical Conductivity (EC), Total Dissolved Solids (TDS) Calcium (CA), Magnesium (MG), Sodium (Na), Potassium (K) and Bacteriological Parameters (E-coli, F-Strp, and Total Coli). In addition, five different WQI performances are compared so that the data can be easily interpreted. The methods used were the weighted arithmetic index (WAI-WQI) Environmental Water Quality Index (CCME-WQI) Canadian Council of Canada (CCME-WQI), Universal Water Quality index (UWQI), Oregon Water Quality Index (OWQI), and Aquatic Toxicity Index (ATI). The applicability of different methodologies is discussed, and significant inconsistencies were observed between the classification results.