The construction of dams can offer many advantages, but their major deterioration could result in failure, including loss of life and property destruction. The purpose of this study is development of the model to predict deterioration using condition index and determine the risk of the failure using Event Tree Analysis. This method is combined between ICOLD and Public Work and Public Housing (PWPH) Guidelines. The results of condition index in Sagung is good condition. The results of annual probability of failure (APF) using Event Tree method is 1.1111 x10-5 .