Sikan River is one of the end branches flowing from Saymareh River. 57% of agricultural land in Dareshaher are located in the environs of this river. In view of the consumption of 1343 tons of chemical fertilizers per year, the effluents from this land can influence the quality of river water. With a view to providing basic management strategies, the seasonal variations in water quality were evaluated. In this way, the quality characteristics of river water which may be influenced by wastewater, was measured in four seasons throughout the year. The NH3ranged from 0.53 to 0.55 mg/lit in spring-summer and 0.19-0.26 mg/lit in autumn-winter which is higher than the drinking water guidelines value for spring-summer, namely <0.3. The nitrate content was within the permissible range for potable water, and varied from 3.7 to 7.3 mg/lit in autumn and summer, respectively. The levels of phosphate in the river varied between 0.007 and 0.032 mg PO4 as P/lit in winter and summer, respectively, which is the standard level for P in water system to prevent eutrophication-related problems, i.e. <0.035 mgP/lit. The sulfate concentration was higher than the recommendation standard of 250 mg/lit in autumn. DO and COD levels were completely acceptable. In sum, the related agricultural activities justify the relative increase of mentioned parameter in summer.