Lake Tana is the largest lake in Ethiopia. It holds 50% of the country's fresh water. It is also the source of the Blue Nile, which contributes up to 60% of the Nile's water.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/africa-ethiopias-lake-tana-losing-fight-water-hyacinth
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/all-africa
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-resources
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/lakes
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ethiopia
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/hyacinth
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/freshwater-ecosystems
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/africa