Presently there is considerable demand for improved sustainable water supply systems globally, even though sedimentation is taking up the most needed reservoir capacity. Dams continuously trap most sediment transported by rivers in its reservoirs. This results in reduced reservoir storage capacity and useful life, and substantially altering the sediments due downstream leading to the riverbank and channel erosion as well as affecting the aquatic habitats. Several available techniques can be used to preserve and mitigate the effects on reservoirs downstream but not often put to use. This paper summarizes the importance of dams vis a vis its effects on rivers, and sedimentation effects on reservoirs. Lastly, the paper outlines a few techniques available for sustainable management of sediment in reservoirs and dams.