Under circumstances of low flow, storage reservoirs, which by evening out the flows allows for their periodic augmentation that ensures water for users and for ecosystems located downstream of reservoirs, become particularly important. The authors are of the opinion that it is vital to use simulation analyses of the work of multi-task storage reservoirs, which in unfavourable hydrologic conditions may be useful in the preparation of crises plans concerning supplying with water and may constitute a base for revising the instructions of water management in reservoirs. This article presents the results of the research carried out for one of those reservoirs – Klimkowka on the Ropa River in the upper Virtual catchment.