Nowadays, many Lakes through the world are subject to eutrophication because of the intensification of agriculture and the growing-up population. The main objective of this study was mapping the spatial and temporal eutrophication status of Lake Tana. A total of 143 samples was taken from the surface of lake water during three different seasons. Transparency, Total Nitrogen, Total Phosphorus chlorophyll-a, Trophic State Index (TSI), spatial and temporal distribution of eutrophication status using Arc-GIS software were determined. The findings of the study showed that TSI varied between 47.50 and 80 in August, 42.5 and 79.2 in December and 39.92 and 78.2 in March. The eutrophication status of Lake Tana was found between Mesotrophic to Hypereutrophic state in August and December and between oligotrophic to Hypereutrophic state in March. But most of Lake Tana eutrophication condition found in eutrophic state which was 56.3% in August, 68.1% in December and 82.4% in March and phosphorous was revealed to be the limiting nutrient in this system. This study provide a good basis for further investigation of the current eutrophication status in order to facilitate sustainable management to ensure community integrity and ecosystem functions of Lake Tana.