eng Science and Education Publishing American Journal of Water Resources 2333-4819 2020-01-16 8 1 21 30 10.12691/ajwr-8-1-3 AJWR2020813 article Yosef Abebe Yimer 1 Li Jin 2 Water Quality Expert, Basins Development Authority, Addis Ababa, Ethiopia, P.O.B -20474/1000 Addis Ababa Department of Geology, State University of New York College at Cortland, Cortland, USA, Office: Bowers Hall 1004 Untreated discharge from industries, domestic wastes, flower farms, and irrigation runoff are among the major sources of pollution in Awash River. Increasing of unregulated lake water discharge is another indication of water degradation in the AR. The objectives of the study were to better understand the discharge of Lake Beseka (LB) and its impact downstream on the water quality of Awash River (AR). 480 samples were collected from 2008 to 2017 and analyzed for more than 20 parameters e.g.; TDS, EC, pH, alkalinity, chloride, bicarbonates, carbonates at four sampling stations. Results showed that the water quality of the AR downstream of the Lake has shown a decreasing trend from 2013 to 2017. The quality of the river water deteriorating due to the release of unregulated Lake water into the AR. The annual mixing ratios of the Lake water with the AR were 6.67%, 13.98%, 45.83%, 27.67%, and 18.73% from 2013 to 2017. Thus, it is essential to install and implement adequate and affordable technologies in order to regulate and quantify amount of flow into the AR from the Lake. If the Lake water continuously drains at its current rate, it would be difficult to control its water quality deteriorating effect and will cause environmental disasters in water and soil salinity problematic downstream of the lake human habitats and the Amibera Irrigation Farms. http://pubs.sciepub.com/ajwr/8/1/3/ajwr-8-1-3.pdf mixing Lake Beseka quantified Awash River water quality degradation salinity