A critical aspect of qualitative management of water resources is the optimal waste load allocation in a river system. Zarrineh Rud is one of the crucial, permanent, water-rich rivers in West Azerbaijan province in the northwest of Iran and the Urmia lake basin. In this study, with the aim of quality management of Zarrineh Rud river, QUAL2K computer simulation model was used. The simulation parameters in this study included discharge, DO, BOD, NO3, NH4, PO4, which were collected from 5 sampling stations S1, S2, S3, S4 and S5 in spring and summer. The results showed that the amount of oxygen saturated solution of Zarrineh River varied between 7-8 mg / l, which is higher than the maximum standard value required. The results showed that BOD could increase by 16% in spring and summer, respectively, and should decrease by 70% in summer to meet the required standard. The station S5 at the river downstream with 3.53 mg/L dissolved oxygen deficit was the most critical point for cold-water fish farming, and the 26th kilometer of the river with a dissolved oxygen deficit of 2.05mg/L was the most critical point for maintaining the aquatic life; therefore, some scenario must be developed for waste load reduction at this station. In order to improve the quality of Zarrineh River, construction of a wastewater treatment plant is necessary for Miandoab sugar factory, villages adjacent to the river and also slaughterhouse. تفاصيل المقالة