As part of a BMBF-funded research project, flow measurements were carried out in a 1:1 laboratory model of water vortex power plant as well as a hydro-numerical simulation. The analysis of the results underpins the observations during the fish experiments conducted in this laboratory model: During the passage of the water vortex power plant fishes are not disoriented due to the relatively low flow velocities and pressures as well as a low turbulent kinetic energy. A collision with the turbine blades has not been detected and is unlikely under the prevalent conditions.