This paper focused on studies carried out on the spillway segment gates at the crest of the “H72 project” dam, to assess their mechanical behavior under seismic loading. Tests were carried out by EDF’s R&D to measure the gates’ dynamic behavior in different operating configurations and to compare the measured data with those obtained using a finite element model. By modeling with caution, the results of the numeric analysis are very similar to the test results. In the case of the “H72” scheme spillway gates, the first natural frequency of the gates in water (10 Hz) is quite different to that in air (24 Hz), which clearly demonstrates the strong influence of water on the gate’s modal behavior. This data can be used to carry out response spectrum analyses using finite elements method to study the gates’ integrity.