Mahadayi River

The Union Government recently informed the Lok Sabha that it has not received any proposal from Karnataka seeking Environmental Clearance (EC) for diversion of the Mahadayi River for various projects.

The development is significant because the Mahadayi River has been at the centre of a long-standing water-sharing dispute between Karnataka and Goa.

Geographical Profile

The Mahadayi River, also known as the Mandovi or Mhadei River, is a rain-fed west-flowing river shared by Karnataka and Goa.

It originates in the Bhimgad Forest of the Western Ghats in Belagavi district of Karnataka. From there, it flows westwards and ultimately enters the Arabian Sea at Panaji in Goa.

The river has a total length of nearly 81 km, of which approximately 29 km lies in Karnataka and 52 km in Goa.

Its basin is particularly important for Goa’s water requirements and covers a substantial part of North Goa.

Important Places and Islands Along the River

The Goan capital, Panaji, and the historic town of Old Goa are located on the left bank of the Mandovi River.

Near Old Goa, the river contains three prominent freshwater islands—Divar, Chorao and Vashee.

The island of Chorao is particularly significant from an ecological perspective because it houses the Salim Ali Bird Sanctuary.

Tributaries

The Mahadayi River is fed by several tributaries, including Rogaro, Kushavati, Nanorem, Nanuz, Valvota and Mapusa.

Among these, the Kalasa and Bhandura streams have become particularly important because of their connection with the inter-state water dispute.

Mahadayi Water Dispute

The Mahadayi River has been at the centre of a decades-long dispute between Karnataka and Goa.

The major point of contention is Karnataka’s proposal to divert water from the Kalasa and Bhandura tributaries of the Mahadayi system towards the Malaprabha basin.

Karnataka has argued that the diversion is required primarily to meet drinking-water needs, whereas Goa has raised concerns regarding the diversion of water from a river that is crucial for its water security and ecological systems.

Mahadayi Water Disputes Tribunal

To adjudicate the inter-state water-sharing dispute, the Mahadayi Water Disputes Tribunal (MWDT) was constituted.

In 2018, the Tribunal allocated 13.42 TMC (380 Mcum) of Mahadayi water to Karnataka.

The allocation included permission for limited diversion from the two disputed streams:

Kalasa: 1.72 TMC

Bhandura: 2.18 TMC

Thus, the dispute involves not only the allocation of river water but also the question of diversion of water across river basins.

Environmental Clearance Context

The recent statement by the Union Government is important because projects involving the diversion of river water can have implications for environmental flows, forests, biodiversity and downstream water availability.

The Mahadayi originates in the ecologically sensitive Western Ghats, making environmental considerations particularly important in assessing projects associated with its diversion.