The hydroelectric power generating system includes a reservoir for retaining a body of water and an outer vessel that surrounds a peripheral wall of the reservoir. A circumferential canal extends between an upper portion of the reservoir peripheral wall and the outer vessel. One or more penstocks extend below the canal between the reservoir and the outer vessel. Each penstock has one or more hydroelectric turbine generators installed therealong. A plurality of primary wind turbines can be disposed on a peripheral wall of the reservoir and a plurality of air columns can be disposed within the reservoir to generate auxiliary power.