Irrigation scheme performance assessment is vital to evaluate the impacts of irrigation practices, to identify performance gaps and to improve system performances. This study was initiated to assess and evaluate the performance of Gumara irrigation scheme using external & internal performance indices such as conveyance efficiency, application efficiency, deep percolation fraction, water delivery performance, maintenance indicators, and estimate the amount of sediment deposited in the main canal and user’s perception on the management of the scheme so as to recommend appropriate measures to improve the scheme management and performance. Primary data were collected by direct measurements, interviews and observations whereas secondary data obtained from design document and different Woreda based data. To determine the conveyance efficiency and losses were measured using current meter, inflow-outflow method in the main and secondary canals at different segments. On farm water application efficiency was evaluated from the amount of water actually applied and from soil moisture measurements. The required amount of water identified by using CROPWAT software was 200l/s during designing the project, but the actual volume of water delivered to the main canal was 151 l/s. There is a total of 142 beneficiaries in the irrigation scheme out of these 59 users were selected randomly from different reaches for interview (at head, middle and tail users) of the scheme. Average conveyance efficiencies were 62.64 % and 57.65% of main and secondary canals of the scheme respectively. The mean conveyance efficiency of the scheme is 71.35% and the average application efficiency was 48.62%. The water delivery performance was about 75.5 %. The effectiveness of infrastructure computed as the ratio of number of functional to total number of structures is approximately 46.94 %, indicating the fact that nonfunctional of irrigation scheme was about 54.06 %. So, the sustainability of the irrigation scheme is not viable. The overall results of the Lower Gumara irrigation scheme performance with respect to the performance indicators displays relatively poor irrigation water operation (34.69%). Lower Gumara main canal total length 1345m and sediment accumulated 349.2-meter cube per season. This amount will extremely reduce the capacity of the main canal. Key words; SSI scheme, performance, efficiency, water, land, irrigation