Hydropower is a well-established renewable power technology, with almost 150 years of history. According to the International Energy Agency, hydropower is the largest renewable source of electricity (generating 71% of the global energy), generating power that is higher than all other renewable technologies combined. Hydro dam projects may cause serious environmental and social problems. While dams are being demolished in developed world and several mega projects are either planned or under construction in the developing world. Many agree that hydro power sector needs to not only focus on energy production but also , include the negative social and environmental externalities caused by dams and recognize the unsustainability of current common practices. Investment in innovative technologies that can move hydropower toward sustainability should be encouraged.