(i) Dams were built in ancient times mainly to harvest the rainwater for irrigation to agricultural fields. After Independence dams were built for integrated development of the river valleys.
(ii) At present construction of large dams has become a controversial issue either due to their failure to meet the objectives or the environmental impact.
(iii) Construction of dams have resulted in problems like excessive sedimentation and salinity, waterlogging, sudden floods, soil erosion, large scale deforestation, extinction of species, health hazards, displacement of local communities and loss of livelihood of tribal communities.
(iv) In some areas, they have triggered earthquakes and natural calamities.
(v) For example, the Narmada Bachao Andolan and Tehri Dam Andolan were the recent issues regarding the construction of dams.
(vi) In recent years the big dams have not been successful in controlling the floods due to large scale sedimentation during the monsoons. Last year in Maharashtra and Gujarat flood situation became critical due to release of water from dams during heavy rains.
(vii) They have resulted in extensive loss of life and property, soil erosion and water pollution. It has also brought about social tensions among the farmers and landless poor.
(viii) Inter-state river water disputes are also the result of sharing the water resources and high cost of construction and maintenance.