The Nilgiris district can be divided into four basins. Moyar Basin and its 24 rivers – draining mainly into the Bhavani reservoir as water supply for irrigation and drinking water in Tamil Nadu. Bhavani Basin and its 26 rivers – draining again to the Bhavani reservoir along the district boundary and onwards again into the Tamil Nadu plains. Both the above basins finally feed into the Cauvery river basin. Kabini basin and its five major rivers drain into Karnataka. Chaliyar basin and its eight rivers feed into Kerala.

The communities in the upper Nilgiris have historically used springs and wetlands as water sources, with streams being used for conveying sewage and other waste. Further downstream, where springs and wetlands are scarce, there is a greater dependence on stream water as the only perennial source of water. These communities are at the receiving end of contamination due to upstream activities.

Streams are also increasingly being tapped by private estates for irrigating tea plantations during the dry season. This results in competition for scarce water resources among estates and downstream communities, resulting in the latter being deprived of access to water. In Sigur plateau, the damming of water in the upper areas for power generation has resulted in streams running dry every year. The proliferation of borewells along with this lack of stream flows has resulted in depletion of groundwater. Most of the open wells and many borewells that the communities depended on for water supply are seasonal now forcing them to transport water at huge costs to meet their water needs. The maintenance of base flows in the Sigur river since last year is a step in the right direction not only for the people but also the wildlife in the region.