The reason of this Diploma is the prospection of higher mineralised waters south of Wildbad-Einöd (WE) in the area of Dürnstein/Stmk. This paper is based on the thesis, that similar to WE, mineralised water rises in the Olsa-fault into the quartenary sediments of the Olsa valley. Geological mapping, combined with the mapping of the springs, built the basis for the working-steps in the field of hydrochemistry and the accompanying soil gas - measurements. The springs showed no anomalies, though in the Olsa-river, where profiles of conductivity and temperature were measured on both sides, aereas with infiltration of higher mineralised groundwater could be identified. In analogy to WE the mineralised waters could ascend with soluble gases, which should be proofed with the aide of soil gas analysis (Helium and CO2). Soil gas profiles were measured, fixed by the data received from the conductivity profile. Samples were taken in a 10m - interval in depth of approx. one meter. Significant higher concentrations of Helium, compared to normal air, were evaluated as anomaly and ascribed to the path of a tectonical fault (Olsa-fault). All the profiles have several aereas with raised concentrations of Helium which leads to the interpretation that the Olsa-fault consists of a system of faults. In selected areas of anomaly additional CO2-measurements were accomplished. These show, as expected, a significant positive correlation to the Helium-data which confirms this methodical approach.