Abstarct: Qualitative indicators are used as effectine managing tools in deasion making programs. Aji-chay is the main river in East Azerbaijan province which ends into Urmia Lake after it passes the Tabriz Plain. Contaminant sources and causes in Tabriz Plain increase the risk for river pollution. So, this stady was aimed to asses and zoning the Aji-chay River baxsed on quality indicators, in order to helps its better management. In the regard water samples were collected at the wet (May 2016) and dry (September 2016) seasons and Parameters EC, TDS, pH, turbidity, suspended solids, major ions, minor ions (nitrate and phosphate), Potentially toxic elements, organic matter (BOD, COD and TOC) and biological constituents (coliform) were measured. baxsed on the results turbidity and EC is high at the upstream which is related to morement of the River in upper red formation (Miocene series)which enhances the chloride, sodium, calcium and sulfate. Arsenic concentrations are exceeding the drinking standards (0.01 ppm) in the all samples mainly from a geogenic sources as well as discharge of wastewater in some areas. The Elements Cd, Mn, Ni, Pb, Mo, Co, Zn, Fe and Al are mainly geogenic, where as Cu, Ba and Cr are mostly originated from anthropogenic activitiy. baxsed on the results, river quality at the wet season is highly controlled by the main branch and Gomnab-chay, but Mehranrood plays the major role in downstream water quality at the dry season due to the its higher discharge rate. The process was confirmed by Piper and Scholler diagrams. Most of the parameters are increased in middle parts at the river where the concentrated sources of contaminats and discharge of wastewater increased the organic and biological constituents and nutrients especily in dry season. Assessing the river quality for agricultural uses baxsed on modified Wilcox diagram shows except for Mehranrood, the other samples are unsuitable for agriculture and the dry season quality is better than the wet. baxsed on the quality indicators of NSFWQI, IRWQISC, Said, Dinius, WQI, OWQI and RPI most of the samples are classified in bad or very bad classes. Comparing the quality indicator revealy that NSFWQI, IRWQISC and Said indicators are more preferred as they better show the trendy in the quality changes.