The negative impact of storage reservoirs on the environment has been well documented, but it appears that under certain circumstances these reservoirs can also help to protect biodiversity. The distribution of adult dragonflies and damselflies was studied in relation to eight environmental variables, in an upland storage reservoir and its feeder rivers located in South-East Poland (East-Central Europe). A total of 25 species were recorded, including 22 in the reservoir. Submerged and floating plants, width of the shallow littoral zone and the water movement/current were found to be the key drivers of the species distribution (pCCA, NMDS). Five species (Ischnura elegans, Sympetrum sanguineum, Platycnemis pennipes, Calopteryx splendens and Erythromma viridulum) were responsible for over 70% of the dissimilarities between the riverine and reservoir sites (SIMPER). In addition, Ischnura elegans, Orthetrum albistylum and Calopteryx virgo were distinguished as the indicator species (IndVal analysis) for the upland river-reservoir hydrological system. Our results highlight some design features of reservoirs that may help to maintain the diversity of odonates, as well as many other groups of aquatic organisms, as the former are well-known indicators of general biodiversity.