Detailed hydropower modeling in mountainous regions such as Switzerland is essential to optimize resource planning and inform the energy transition. To foster this process, we introduce HP-CatCH, an open-access dataset that maps topological configurations of hydropower cascades in Switzerland and links hydropower infrastructure to the associated hydrological catchments. In total, the components and topology of 48 cascades are defined, including 106 reservoirs and covering 95 % and 93 % of Swiss hydropower storage and pumped-storage capacity, respectively. Additionally, 601 run-of-river hydropower plants are modeled. The potential of the dataset is demonstrated by reconstructing historical inflows into reservoirs and run-of-river hydropower plants using simulated runoff from the hydrological model PREVAH. The resulting inflows exhibit large spatiotemporal variability, highlighting the relevance of such detailed and spatially explicit hydropower representation for energy system modeling and hydroclimatic impacts studies.