Qualititaive assessment of the Aji-Chay River (Tabriz plain) based on the specific uses quality indices

Aji-Chay is one of the greatest permanent rivers in Tabriz study area that finally flows into the Uremia Lake. The river quality is degraded by different pollution sources along its way especially in the Tabriz Plain. In this research for assessing quality of the Aji-Chay River using water quality indices for specific uses, water samples were collected from 16 sampling points along the river in wet (May 2016) and dry (September 2016) seasons. Physicochemical parameters including pH, temperature (T), turbidity (Turb), electrical conductivity (EC), total solids (TS), total dissolved solid (TDS), inorganic constituents including major (sodium, potassium, Calcium, Magnesium, Chloride, Sulfate, Bicarbonate) and minor (nitrate and phosphate) ions, inorganic parameters comprising dissolved oxygen (DO), chemical oxygen demand (COD), biological oxygen demand (BOD), and biological parameters such as total coliform (T.C) and fecal coliforms (F.C) were measured. Based on the results, values of some parameters are above the pertaining standards of Iranian drinking water. Assessing quality of the Aji-Chay river using river pollution index (RPI), Oregon water quality index (OWQI), Said index, Dinius index and weighted arithmetic water quality index (WQI) confirmed very bad qualitative statue of the river in most stations especially in the middle parts of the Tabriz plain due to the entry of the pollutant sources. Based on the results quality indices of Said, Dinius and WQI are suitable ones for assessing quality of the river for particular purposes and then its qualitative management as