River Basin High Council and Authorities were established under proclamation No.534/1999 E.C. so as to implement the principle of an integrated water resource management. Awash Basin Authority, thus, is established in accordance with Awash Basin High Council and Authorities establishment Council of Ministers Regulation No.156/2000 E.C.
There are twelve major river basins in Ethiopia of which Awash Basin is one and the most utilized River basin so far. Awash Basin covers parts of Afar, Amhara, Oromia, Somali Regional States, SNNP and Addis Ababa and Dire Dawa administrative councils. It is the fourth populous basin in Ethiopia and ranks the 3rd of all basins of Ethiopia in terms of population density and stands 4th and 7th in its area and volume of water respectively. The overall population in the Awash Basin is estimated to be 14.9 million from the CSA report of 2007 G.C. -more than 65% of this concentrated in the Upper Awash. The Awash Basin covers a total area of 116,000 km2 and has a annual flow of 4.9 billion m3.
The Awash River rises on the high plateau to the West of Addis Ababa, at an altitude of about 3,000 m and is fed by several major tributaries; including Kessem, Kebena, Awadi, Arso, Ataye, Borkena, Cheleka, Mile and Logiya rivers. The part of the catchment situated in the dry east of the river, accounting for some 40% of the total basin area, does not contribute any significant surface runoff to the river. The total length of the Awash river is approximately 1,250 km.
Awash Basin is the most developed basin in Ethiopia due to availability of land suitable for agriculture, water resources that can be easily tapped, and its strategic location. The estimated irrigation potential is about 206,000 ha out of which more than 160,000 ha or 77.7% (current survey excluding hectares less than 2.5 ha) is already developed by surface irrigation systems and it also serves for drinking water supply for big towns and rural community, hydropower and fisheries. There is usual tension during the pick irrigation time especially in the month of May and June. The Upper Awash, mainly characterized by urbanization and wetter hydrological regime, receives high rainfall while the major part of the basin has short and intense rainy seasons with highly unreliable rainfall leading to frequent droughts and floods in the middle and lower part of the basin. Rain fed cultivation has been increasingly becoming unreliable in the larger lower part of the basin. All its tributaries originate from Amhara and Oromia highlands where most of the steep lands are under cultivation. This improper land use coupled with high rainfall intensity and rapid urbanization resulted in increasingly frequent floods affecting rangelands, cultivated lands and social and economic infrastructure in the lower, middle and even in the most upper parts of the basin.