Jaak Tambets, Rein Järvekülg and Meelis Tambets are convinced that the „green” hydroenergy is far from being sustainable or nature-friendly in Estonia. The acknowledged hydrobiologists describe the negative aspects of hydroenergy to riverine habitats and fauna as well as to society: the speedwater habitats upstream from the dam become damaged; the water volume of the river changes and the minimum water volume is decreased; the qualities of river water become deteriorated; dams become barriers for fish because of poorly designed fish ladders; the sediments behind the dam may cause major changes downstream if let go at once; economically, fish catch is notably decreased; often the environmental requirements to hydroenergy facilities are not met.