Awash River water has impaired by various types of pollution owing to waste released from different socioeconomic activities in its basin. This study aimed to evaluate irrigation water quality of Awash River and its tributaries in the basin used for irrigation purposes. Sampling sites were identified based on the pollution sources, accessibility, and land use coverage. A total of 17 sampling sites were chosen along the Awash River and samplings were collected four times a year through different seasons. The overall water quality and suitability for irrigation is explained using multiple water quality parameters such as pH, EC, SAR, RSC, Na+, K+, Ca+Mg, CO32-, HCO3- and Cl-. The obtained results showed that all quality parameters at Beseka Lake exceed the maximum permissible limit of suitability for irrigation. It is generally conceivable that the physicochemical characteristic of Awash River varies in different water quality parameters at different sites. Only Beseka Lake and Meteka hotspring water exceeds the pH and SAR permissible limit and EC at Mojo, Wonji, Beseka, Melkasedi, Werer, Ambash, Meteka and Meteka hot spring shows medium to high salinity scale while RSC was very hign at Beseka, Melkasedi, Meteka hot spring, Ambash, Meteka Mojo, Werer, Assayta, Wonji, Dupty, Tibila, Metehara and Afambo respectively. Establishment of wastewater treatment plants for industries and storm water quality management at hotspot areas are recommended to improve the water quality and dispatch proportion need to be considered in the future.

Keywords: Irrigation water quality; Awash River water; quality parameters; soluble salts; Permissible limit; physicochemical characteristics