Conservation and improvement of the environment in dam reservoirs

Dams in Japan have contributed a great deal to the protection of life and properties, effectively prevented damage caused by floods, supported the maintenance of the normal functions of the river flow, and improved and conserved river environments. However, in recent years, many people in Japan have raised questions about the existing dams and dam projects without correct evaluation of the past impacts of dams. It has therefore become difficult to plan new dam projects and to operate existing dams properly as intended. People opposed to dams have commonly argued that dams inflict more damage on the environment than any other structure. For the reason that a dam will submerge its natural surroundings, counter measures to minimize its effects on the environment as much as possible should be taken, through every stage of the project. Particular attention should be given at the planning stage of dam projects. The latest developments in the conservation of the environment following dam construction and the concrete measures taken by dam constructors to follow the regulations concerned in Japan are described. The mitigation of the environmental impacts of dams and the restoration of the environments of downstream rivers are now the major issues.