The Salzburg basin was filled in last late and postglacial stage with fine clastic lacustrine sediments and fluvial sands. These lacustrine sediments, called "Salzburger Seeton”, build the impermeable layer in the underground. The groundwater flows in sand and gravel above the impermeable layer from the Untersberg in the south to the north, below the “Leopoldskroner Moor”, in the direction to Salzburg. In the northeast the groundwater infiltrates the Salzach, in the northwest the Glan. The groundwater horizon is a few meters to a few tens of meters thick. The aquifer is continuous and unstressed. Only in areas of the “Leopoldskroner Moor” there can be strained circumstances caused by fine sand and silt layers. A second stagnating aquifer in a higher horizon is formed above the deeper aquifer. To characterize the complex hydrological and hydrogeological situation of the area Leopoldskron, with special reference to the interaction groundwater-surface water, data in the form of well logs were collected in offices. All relevant data was manually entered into appropriate programs. This dataset is needed to make hydrogeological interpretations. In addition for 13 months groundwater monitoring for the parameters, depth of the groundwater, conductivity and PH-value was made. At nine selected groundwater measurement locations a chemical groundwater analysis was carried out. Moreover, the sediment filling of the Salzburg basin has undergone a sedimentological and geomorphological consideration, to clarify the question: the sands and gravels were transported from the Salzach or Königsseeache? The results of these studies are: The Königsseeache has without doubt transported the sands and gravels in the area of the “Leopoldskroner Moor”. The groundwater recharge and the groundwater fluctuations in the basin and on the lower mountain slopes are only influenced by precipitation. There are river-groundwater interactions as well as higher groundwater-deeper groundwater interactions. The groundwater chemistry is of calcareous-alkaline type and mainly reflects the geology of the basin filling. The groundwater under the “Leopoldskroner Moor” is reducing. The TOC (Total Organic Carbon) content and the electrical conductivity of the groundwater are increased. Outside the “Leopoldskron Moor” increased nitrate levels occur. Groundwater exploitation as drinking water in the study area should not be allowed by the following reasons: 1) The groundwater fluctuations are high and precipitation affected, which means that there is a rapid degradation of groundwater by the abstraction of drinking water and thus it could come to increasing infiltration from river water. However, this river water, primarily the Glan, shows strong influence of the higher aquifer, which manifests itself in an increase in the conductivity and temperature of the Glan to the direction of Salzburg. 2) The groundwater extraction and the lowering of the water table, would lead to increased subsidence in centimeter and decimeter range in this area. 3) Since the groundwater recharge is done by precipitation, it can be concluded that there is only small protective sediment coverage and the vulnerability is low. 4) The groundwater chemistry, with elevated levels of nitrate, TOC and conductivity values is not suitable as drinking water without extensive and elaborate treatment measures. 5) The interaction groundwater-surface water and the interaction higher groundwater horizon-deeper groundwater layer are very complex and are not yet well understood.