Ethiopia has a huge water potential resource that can be used for irrigation, hydropower generation and fishery. Ribb irrigation dam is one of the Nile Irrigation Drainage Projects of Ethiopia (ENIDP) which is found in the eastern part of Lake Tana in South Gondar Zone between Ebinat and Farta Districts. This dam was constructed to irrigate 20,000 ha of land in Fogera and Libokemkem plain to cope up the national and regional food insecurity problems. However, due to the absence of integrated upper catchment treatment, this dam may not meet its primary objective (Irrigation) for the expected period of time. Thus, the objectives of this study were conducted to analysis the water balance, sediment yield and life expectancy of the reservoir. To accomplish this study, both primary (field and laboratory) and secondary data were used. So, the river discharge and sediment data monitoring and collection was conducted through rivers velocity measurement, sediment sample collection at the gauged stations and measuring the suspended sediment concentration (using portable TSS). Rainfall data of the area was collected using Tipping Bucket rain gauge and evaporation was measured using a standard pan. Following the data analysis, different rating curves were developed such as depth vs. velocity, depth vs. cross sectional area and depths vs. discharge. The result showed that the water balance of the reservoir storage capacity was surplus (+), the annual sediment generated from the three rivers catchments and entering to the reservoir was 2.553*106 tons (2.201*106 m 3), and out of this Ribb river contributed the highest total sediment entering the reservoir (44.38 %). The area specific sediment yield (SSY) of Hamus, Mello and Ribb were 3,415.46 t km- 2 yr -1; 6,933.33 t km-2yr-1 and 3,438.8 3 t km-2 yr-1 respectively with an average value of 3,976.39 t km-2 yr-1. The net annual deposited sediment in the reservoir was 1.689*106 tons (1.456*106 m3) with sedimentation rate & trap efficiency of 0.62 % and 66.16 %, respectively. With this water balance and sedimentation rate, the life expectancy of the reservoir will be decreased by 61.76 %, the reservoir expected to silt up after 19 years. From this study, it is possible to conclude that the reservoir will not meet its primary objective (Irrigation) as projected by the design document; unless upper watersheds treatment and sustainable utilization of Ribb reservoir campaign planned and implemented by the cooperation of different stake holders