In this study, to develop a risk assessment tool for geotechnical risk evaluation of local reservoirs. Generally, local reservoirs had some problems which is ageing, poorly compaction, differential settlement, leakage of adjacent conduit, material problem of adjacent spillway etc. Therefore, this study to develop geotechnical failure mode scenario for local reservoirs, and risk assessment tool considering internal erosion process. In addition, to carried out risk evaluation for pilot reservoirs and analyzed failure probability.