The first objective of this work is to assess the temporal variation of Cu, Zn, Pb, Cd, Crrnand Ni in sediments of the Aba Samuel Reservoir Lake, south west of Addis Ababa. Twornsediment cores with 44 and 49 cm length were recovered at the proximity of the dam inrnthe south (Core 1) and at the western shore (Core 2). Sediment slices have been takenrnfrom top, middle and bottom parts of the cores for analysis.rnSedimentation rate was estimated using constant rate and therefore by linearrnextrapolation using the age of the dam as a base line (68 yrs). Considering 4m averagerndepth of sediment over the span of time the dam construction took, an averagernsedimentation rate of 6cm/yr has been calculated. The core bottom sediments containrntherefore the history over the last 7 years.rnThe result of the analyzed heavy metals shows a general increasing trend from the bottomrnto the top samples in the cores. The amounts currently obtained, except for Nickel andrncopper, are still below the standard value. However, the value of all analyzed metals willrnbe higher than the standard if the current concentration is to be projected towards the nextrn7 years.rnNickel concentration is higher than the standard value for both sediment cores.rnComparing the concentrations in the respective sediment cores, sediment core 2 has anrnaverage value of 51.4 mg/kg and sediment core 1 contains 42.5 mg/kg on average. Thisrnshows the slight spatial variation within the lake. The variation could be due torndifferential trapping along the path of the water and the closeness of sediment core 2 tornthe inlet point of the lake than sediment core 1.rnNutrient analyses have been conducted for the lake water. Nitrate and phosphate showrndecreasing trends from the inlet towards the outlet of the lake; this could be due to thernuptake of these nutrients by water hyacinth and the settlement of nutrients along withrnsediments. While, ammonia increases from the inlet to the outlet, possibly owing to thernprevalence of a reducing environment which results in the formation of ammonia.rnFrom this study it was possible to observe that, the pollution load in the Aba SamuelrnLake is increasing. This confirms the importance of anthropogenic load becomingrnimportant in the background of possible constant natural supply. Therefore, properrnmonitoring of pollutants in the lake environment is crucial.