The design, construction and operating of spillways, as an important part of dams, are very important, because of the parameter of flood discharge capacity under climate change effects. In addition to observe the trends, risks of spillways must be evaluated by risk analysis using same observed maximum flow data. By using maximum flow parameters, it is reported existence the trends and safety level of spillways for selected dams. That results show us, the process of observation of updated maximum flow data and its effect on risk level for dam safety. At the same time, it is evaluated the risk level of some previous studies under updated data.