Even as resistance grows to large dams worldwide, at least six big multipurpose projects are being planned in the upper reaches of Arunachal Pradesh. In fact, a forerunner to these dams in Lohit district of the state was conceived exactly 30 years ago – much before Narmada Sagar became a big issue in the country. The original proposal was to construct a single 257-metre-high rock-fill dam near Gerukamukh on the Assam-Arunachal border. The amended proposal is to construct at least six dams. It is, of course, a misnomer to say that the Subansiri-Dihang dam is one huge project. Actually, there would be six multipurpose dams, on the rivers Dihang and Subansiri, put together in the upper reaches of Arunachal Pradesh (see table)
Dihang and Subansiri rivers originate in China. They enter India in the upper reaches of Arunachal Pradesh and finally merge into the Brahmaputra. In fact, experts say that most of the water that flows into the Brahmaputra is contributed by these two tributaries. The original idea was therefore to dam these two rivers in order to control the Brahmaputra’s floods that ravage large parts of Assam during the monsoons.