Water quality impairment, due to anthropogenic activities and limited enforcement capacity, is a rapidly growing threat to water security as well as public health in developing countries. Cumulative effects of deteriorating water quality undoubtedly put pressure on public health and socio-economic developments. For example, most industries in Ethiopia discharge their effluent directly into freshwater systems without any treatment process. The problem is severe for rivers such as the Awash that pass through major cities. Although there were a few studies that looked into the issue, there is a lack of comprehensive water quality impact assessment on agriculture, health, and socio-economics. This article systematically summarizes current research on water quality issues in the Awash River Basin to generate comprehensive information that captures the water quality status of the river and impacts of water contamination, and identify information and management gaps. Results showed that water quality degradation along the river course and in selected tributaries exceeds water quality standards by the WHO and national guidelines. For example, E-coli bacteria concentration in two tributaries, Tinishu and Tiliku Akaki, reach up to 6.68 and 6.61 billion CFU 100 ml/L. Virological profile of creeks receiving wastewater from hospitals in the City of Addis Ababa contains coliphages levels reaching as high as 5.2 × 103 pfu/100 ml for urban rivers and up to 4.92 × 103 pfu/100 ml. Heavy metals that far exceed the tolerable levels for humans were also detected in vegetables produced using impaired water. Heavy metals such as Cd, Cr, Cu, Hg, Ni, and Zn were detected in potato, Zn and Hg in Cabbage, and Cr in onion and red beet. Lettuce irrigated with Akaki river water found to contain 0.263 (Cd), 420 (Fe), 13.44 (Zn), 7.87 (Cr), 7.49 (Cu), and 6.55 (Pb) in mg/kg both in excess of WHO guideline. In addition, a high concentration of Cr has been also found in fish tissues. There has never been a systematic evaluation of the impact of contaminated water in the Awash Basin. Comprehensive impact of water quality investigation that takes into account the different pollutants dynamic needs to be made to protect the well being of downstream beneficiaries including the aquatic ecosystem. In conclusion the systematic review has shown that for a river that cross-through emerging mega-city like Addis Ababa, the human and ecosystem health impact of aquatic ecosystems pollution should not afterthought action

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Developing countries like Ethiopia are grabbling with rapid population growth, urbanization, agricultural intensification, and climate change which put intense pressure on the availability and quality of water resources. The surface water quality degradation is exacerbating due to increasing urbanization and agricultural activities. The average annual fertilizer use in Ethiopia increased from 132,522 metric tons (mt) in 1996 to 858,825 mt in 2015. Pesticide use also increases significantly from 3,327.7 mt/y in 2006 to 4,211.5 mt/y in 2010. The Awash river is one of the most affected rivers by intensified irrigation schemes, industrial, and urbanization pollution. The Awash river and its tributaries are used for domestic, irrigation, industrial, and recreational purposes. However, as per Canadian water quality indices for the drinking and irrigation water quality, the upper Awash basin scored 34.79, and 46.39, respectively, in the poor and marginal categories; whereas the middle/lower basin indicated 32.25 and 62.78 in poor and marginal ranges, respectively. Dissolved phosphorous in the headwater tributaries is about 0.51 mg/l which is beyond the threshold (0.15 mg/l). The surface water quality impairment is severe in the upper Awash basin where more than 90% of Addis Ababa's industries discharge their waste into nearby waterways without treatment; about 30% of the population lacks access to a liquid waste disposal and treatment facility; only 16% of the population is connected to sewage system, and 25% of the total waste generated enters freshwater systems without treatment. Many studies on surface water quality are reviewed and many of them are inconclusive for a number of reasons. For example, no comprehensive surface water quality research, lack of detailed combined spatial and temporal surface water quality data, and analysis to show the overall picture of the basin are a few of them. Despite the existence of the policy and legal tools, enforcement is lacking. Improving the ecological health of rivers necessitates policy revision as well as increased knowledge and engagement among implementers.