Examining the earthquake behaviors of important water structures such as arch dams is of great importance for the future and safety of these structures. Besides, different reservoir heights, which occur as a result of different seasonal precipitation, can cause great losses in the structural behavior of arch dams. For this reason, in this study, the effects of various reservoir water heights on the earthquake behavior of arch dams are evaluated by considering a creep material model. Ermenek dam, one of the highest dams in Turkey, is chosen for the 3D (3D) numerical analyses. This dam has 4 different gallery spaces in its body and it has a body height of 220 m. While creating a 3D finite-different model of the dam, the creep material models are utilized for the concrete and foundation sections. For the 3D earthquake analyses, free-field and quiet nonreflecting boundary conditions (BCs) are defined to the boundaries of the model. Besides, fix BCs are added to the base of the dam. While creating the gallery spaces of the dam, the original dam project is taken into consideration, and attention is paid to creating the oval geometry of the gallery spaces following the project. For earthquake analyses, 4 different water levels (25 m, 85 m, 150 m, and 200 m) are considered, and hydrostatic forces and water table are used while generating the reservoir water. Furthermore, a total of 18 different strong ground motions are used in the earthquake analyses to examine the earthquake behavior of the dam. According to the earthquake analyses, it is concluded that different reservoir heights have great effects on the earthquake behavior of the Ermenek dam. Moreover, it has been observed that the height of the reservoir water causes significant earthquake stress and displacement differences around the gallery spaces of the dam.