Soil erosion by water is the most pressing environmental problem in Ethiopia, particularly inrnhighlands where topography is highly rugged, population pressure is high, steep lands wererncultivated, rainfall is erosive , soil type is erodible , poor soil conservation practices are adoptedrnand land use land cover change (LULCC) is accelerated. Assessment of impact of LULCC onrnsoil loss and expansion of Lake Boyo was done in Shashogo Woreda, southern Ethiopia. Tornanalyze LULCC during 1973-2005, landsat images of 1973, 1984 and 2005 were used andrnfound that land use/land cover classes bare land, cultivated land and water body werernincreasing on expense of decrease in wet grass lad, bush lands and grazing lands. UniversalrnSoil Loss Equation (USLE) model was to analyze the rate of soil loss in 1973 and 2005 usingrnGeographic Information System (GIS) and remote sensing. The finding revealed that thernannual mean soil loss which was 3.33t/ha/y in 1973 was increased to 13.41t/ha/y in 2005 duernto LULCC and poor soil conservation practices. This implies that erosion model (USLE)rnpredicted an increase in the amount of soil loss due to LULCC during 1973-2005. Forrnvalidity, the current result was compared with earlier findings in the same agro-ecologicalrnregions and found a good agreement. Thirty micro-watersheds were delineated to analyzed andrnidentify sever erosion areas for prioritization for conservation purpose. The result showed thatrnmean annual soil loss rate is highest at upstream of Guder river and it is even higher that upperrnlimit of the tolerable range (>16t/ha/y). To access trend of expansion of Boyo Lake, satelliternimages of 1973, 1984, 2000 and 2005 were used and found that the lake is expandingrnexponentially through time causing pressure on other land use/land cover classes. Thernincreasing of the annual mean soil loss rate at upstream of Guder River increased therndownstream sedimentation impact in Boyo lake and could be the cause for the expansion ofrnBoyo Lake. Mean annual soil loss from each land use/ land cover class was analyzed andrnfound that bare land have the highest rate of soil loss and highest next to cultivated land inrncontributing total soil loss in the study area.