Abstract: The Gördes Dam has been planned for flood-preventing on Gördes River which is one of the important branches ofGediz River. The aim of this study is to investigate the detailed geological characteristics of the dam site and adjacent areas and discoverprobable water-leakages horn the reservoir area.The study region is stituated in the Izmir-Ankara zone and Menderes Massif. The Izmir-Ankara zone consists of ophiolite, flysch andvariouses carbonate rocks mainly of Cretaceous age. The metamorphic rocks of the Menderes Massif, consist of marble, mica-schist andphyllites region. The allochthonous ophiolite bodies are mainly composed of serpantinite, gabbro, and basic volcanics, and overthruston to the Cretaceous carbonates and Menderes Massif`s rocks. The two different flysch units- exposed in this region, are separated carbonate rocks from each other with platform-type Cretaceous. The contact is conformable and transitional between carbonate and flysch unitsin all places. Locally, the lower flysch unit rests unconformably on the metamorphic rocks of the Menderes Massif.The majority of the faults raughly represent a NE-NW trend and are shown in high-dipping systems in this region. The thrust faultsgenerally display N-NW trends in the study area. Hie discharges of the Akpmar springs are controlled by the NE-trending Ahmetler fault,and probably cause to the leakages from the reservoir, due to the karstic and morphological features of this fault