Eutrophication is one of the most challenging environmental matters in water reservoirs;rnhigh concentration of nutrients cause algal bloom. This study was conducted on LegedadirnReservoir to determine the trophic status and the source of nutrients. Systematic samplingrndesign was employed to select sampling sites from which water, sediment, and soil samplesrnwere collected and analyzed by standard methods for their nutrient and chlorophyll-arncontents from December to February and June. The mean concentration of total nitrogenrnand total phosphorus were 15.58 mg/L and 0.92 mg/L in the water of the reservoir,rnrespectively, which support the growth of algae and aquatic plants. The trophic status of thernwater in Legedadi Reservoir was found to be mesotrophic condition based uponrnchlorophyll-a (4.98 Î¼g/L) concentration. The reservoir was phosphorus limited. Physicalrnand chemical characteristics of water like pH, dissolved oxygen and temperature is found atrnits optimum level and favorable to aquatic organisms. On the other hand, turbidity in waterrnwas relatively very high (471.64 NTU) and increased significantly during rainy season. ThernAvailable P and TN ranges from (15.43 - 23.55 ppm, 937.50 - 1137.50 ppm) in the sedimentrnand (19.56 - 28.94 ppm, 1150 - 1262.50 ppm) in the soil samples of the tributaries,rnrespectively, which is found to be good indicative of the source of the nutrients of thernreservoir. Nutrient deposition in the sediment concentrated at the downstream than thernupstream of the tributaries. Therefore, the reservoir nutrient/Available P contributed by thernsediments of Lege Sendafa (25.41ppm) followed by Lege Bolo (19.88ppm) and Lege Berirn(13.73ppm) Rivers. Thus the reservoir requires reductions of nutrient loading by applyingrnappropriate physical and biological soil conservation practices.rnKey words: Legedadi Reservoir, Eutrophication, Phosphorous, Nitrogen and Chlorophyll a.