The inundation area of the Lempake Reservoir is currently almost 90% covered by water plants and there is very serious sedimentation in the reservoir. In several locations of the reservoir inundation there is piling up by residents, even in the right side of the reservoir has been piling up for the road body. The condition of the Lempake reservoir has decreased in capacity from year to year. At normal water level, the capacity of Lempake Reservoir in 2013 was 0.76 million m3 and in 2018 was 0.39 million m3. Therefore, it is needed an effort to control sedimentation in the reservoir, including by conducting studies on the sedimentation conditions of the reservoir, analyzing the sedimentation rate of the reservoir so that it can be seen the volume of sediment that must be dredged, so that it can reduce flooding that usually occurs in the location. The study was carried out by analyzing the volume of sedimentation in the reservoir by using the ArcGIS program and analyzing the flood discharge design at the site by conducting flood tracking at the Pasar Segiri River outlet point. The analysis results show that the capacity volume in 2020 is predicted to be 0.241 million m3 with an annual sediment rate of 0.074 million m3. From the analysis of the flood tracing in the Lempake Dam spillway, the flood reduction values obtained at the 1.01 year return period were 67.0% (scenario 1), 78.4% (scenario 2), and 80.8% (scenario 3).