The primary energy resources of Turkey are quite limited; therefore Turkey has to develop her water power potential, a renewable and clean energy resource, to produce electrical energy. The hydroelectric energy production of Turkey was barely 1 TWh/y in 1960; the production capacity increased to around 75 TWh/y in 2017. The economically feasible hydroelectric potential of Turkey is in the order of 150 TWh/y. Turkey anticipates to harness the remaining part of this potential, so that several hundreds of major hydroelectric power plants (HEPP) have still to be constructed in the near future. The discharge rates of the water courses in Turkey show significant seasonal variations as well as large annual fluctuations; hence, the discharge regulation by means of large reservoirs, created by dams, becomes a necessity. The additional evaporation from the reservoirs of the dams should not be regarded as an unnecessary loss, but has to be conceived as an in-kind operational cost. Hydroelectric schemes, especially those associated with dams, are the most versatile power plant types to cover the peak power demands. The reservoirs of dams serve often, directly or indirectly, to mitigate the floods. They may also serve to regulate the discharges for irrigation purposes in the context of multipurpose projects. Nevertheless, any hydraulic scheme is an intervention to the nature, and special care should be given not to unnecessarily harm the people and the environment, during the construction as well as the operation stages of water power schemes. The harnessing of water power in Turkey is primarily based on hydroelectric plants associated with large dams and on high-head diversion plants. Embankment dams dominate as dam type, but interesting concrete dams do also exist. The water power plant at the toe of Ataturk dam, with 2400 MW capacity, is the largest hydroelectric scheme in Turkey.