Review of characterization, factors, impacts, and solutions of Lake eutrophication: lesson for lake Tana, Ethiopia

Lake eutrophication and water quality deterioration have become a major environmental problem in urban areas and fertilized basins in developing countries across the world. This paper reviews the characterization, driving factors, and impacts of lake eutrophication as well as the mechanism of preventing and recovering lake eutrophication with case studies of eutrophic lakes across the world including Lake Tana, Ethiopia. In most waterbodies including lakes and reservoirs, total phosphorus concentration, chlorophyll a concentration, and Secchi disk visibility in association with species composition are the common criteria to classify lakes and reservoir as oligotrophic, mesotrophic, and eutrophic. Nutrient-rich runoff from cultivated land and industrialized and urbanized cities concentrated in phosphorus are the critical factors that drove eutrophication in water bodies. Among others, controlling external loading of nutrient, ecological, and mechanical methods were found to be common mechanisms to prevent and recover lake eutrophication. Avoiding the factors that are under human control, i.e., a reduction of external loading of nutrients especially targeted on phosphorus reduction into the water basins, relocates sewage, industrial and domestic waste discharges to be lined out of the catchment of the lake. Furthermore, motivating the community to use less phosphorus-containing fertilizers and promoting phosphorus-free detergents are suggested solutions to sustainably prevent and reduce eutrophication in the long run. These could be some possible measures to safeguard endangered Lake Tana of Ethiopia.