Water Quality of Lake Tana Basin, Upper Blue Nile, Ethiopia. A Review of Available Data

Abstract

Water is at the forefront of the economic agenda of Ethiopian government and Tana basinLake Tana basin has been identified as a major economic corridor because of the basin’s immense water resource potential for socioeconomic development. For effective and sustainable utilization of water resources in the basin, it is essential to assess the water quality in spatial and temporal dimensions. Nonetheless, scientific information on Ethiopian water bodies is rare and the available ones are of expeditious origin. In Tana basin, there is no detailed and systematic characterization of water quality based on long term and spatially representative data, due to the absence of a sustainable monitoring program. Despite the fact that data and studies are fragmentary, the available information on Lake Tana indicates that the trophic status of the lake has gradually changed to mesotrophic and eutrophic in some places due to nutrient loads. Sedimentation is a threat to Lake Tana. FecalFecal pollutionPollution and toxigenicToxigenic bacteria cyanobacteria are detected in the lake especially in the shores and river mouths. Although the current dataset on water and Lake bottom sediment characteristics and quality impacts is spatially and temporally limited, the available information indicates occurrence of potential anthropogenic pollution mainly on river mouths and shore areas. Impairment of water quality has been going on for years, which has significantly affected the basin’s potential for agriculture, industryIndustry , hydroelectric, ecosystem, water supply and recreation sectors. Sedimentation, eutrophicationEutrophication , fecal pollution, wetland encroachment and hydrological alterations have been identified as main issues of water quality management in the Lake Tana basin. Efficient monitoring programs based on a practical selection of robust water quality indicators are recommended for the basin.