Many of the world’s concrete dams are approaching the end of their expected service life and many of these dams are cracked due to environmental effects. It is thus desirable to be able to extend the service life of many of these dams. It is therefore important to develop reliable methods of analysis to assess the current status of these dams and to determine the safety of these, partly damaged structures. A slender reinforced concrete arch dam is used as a case study with the aim of predicting the structural response, the cracks found in-situ and of assessing the safety of the dam. This dam has cracked extensively along the downstream face primarily due to seasonal temperature variations. A detailed finite element model has been developed to simulate the history of the dam with the variations in ambient conditions that have occurred over its lifetime. The results show good agreement regarding both the crack pattern and displacement of the dam. A procedure to simulate a progressive dam failure, starting from the current state, is utilized to assess the current level of safety. The results show that the cracking has a limited effect on the safety factor of the dam.