The Water Quality Index (WQI) is an important parameter in describing the water resources' suitability for human uses and is one of the most effective methods of describing water quality and indicative of assessing water quality and suitability for human utilization and the health of ecosystems. WQI of the Canadian Council of Ministers of the Environment (CCME) was used in the study to describe the Shatt al-Arab water quality in Basrah Southern Iraq, and its suitability for drinking use. The data for analyzing river water samples were adopted from five stations along the river every month during the years from 2014 to 2018 by the Iraqi Ministry of Environment, as it included the measurement of acidity function PH, Dissolved Oxygen DO, phosphorous PO4, nitrate NO3, Calcium Ca, potassium K, magnesium Mg, sodium Na, Total Hardness TH, sulfates SO4, chlorides Cl, Electrical Conductivity EC, Total Soluble Salts TDS, and Alkalinity ALK. The distributions of water quality index values along the river were mapped by GIS techniques. Study results were referring to illustrate the poor level of the water quality status of Shatt al-Arab in all study periods at all monitoring stations. The reason for this is due to the deterioration of fresh water quality drained from the Tigris and Euphrates, and the provision of salt wedges from the Arabian Gulf. However, with the continuous discharge of sewage water, industrial and oil effluents and sewage discharged from urban areas, the water quality of Shatt al-Arab was declined during the study period.
