The Kopal River in the Khozestan province, IRAN, is the most important river on the plain and water capability for
agriculture in this plain was provided from this river. It is planning to construct a reservoir on the river in the Haftgel
area in order to supply the agriculture and drinking consumptions in that region. Therefore, the study on the water
quality of this river is very important role in take any decision. In this paper the water quality parameters such as
HCO3- SO4-2 CL-1 K+ Na+ Mg+2 Ca+2 and SO4-2 are evaluated base on the sampled data which taken in the
Hydrometric station in the period from 1981-2001. In general, 162 series data are used. For assessment of the water
the Wilcox diagram are used. Base on this criterion, the water of Kopal River has high harness and it is not suitable
for dinking uses. Also the water is classified as C4S2, C4S3 and C4S4; therefore it is not suitable for the irrigation
consumptions
