Mekedatu Dam: Adding to the troubled waters of Karnataka-Tamil Nadu Cauvery river dispute

Karnataka applied for a sanction to the union ministry on May 30, furnishing the documents required including a draft pre-feasibility report (DPR), draft ToRs, and necessary drawings and maps. The Tamil Nadu authorities were apparently unaware of the development until the union ministry sought a report on the project from the inter-state Cauvery Water Management Authority (CWMA).

The proposed Balancing Reservoir Project envisages building the dam at Mekedatu village on the outskirts of Bengaluru to store 67 tmc of water and generate 400 MW of electricity. Karnataka hopes to pump 4.5 tmc of drinking water to the water-starved urban areas of Bengaluru and neighbouring Kanakapura. Tamil Nadu is deeply concerned that the project could further diminish its already limited water supply from the Cauvery River, which is crucial for preserving extensive paddy fields in the Thanjavur-Nagapattinam-Trichy delta region.

Conservationists in both states oppose the project because it would submerge 7,862.64 acres of the highly fragile Cauvery Wildlife Sanctuary and 4619.63 acres of adjoining reserve forests.

According to a CWMA official, who asked not to be named, the Central Water Commission (CWC) has held on to relevant project files, without acting on them, for a period of time because of stiff opposition from Tamil Nadu and environmentalists. Moreover, the union ministry clarified in 2019 that the project would be considered only if an amicable solution is reached with the Tamil Nadu government.

However, Chennai is furious at Karnataka deputy chief minister D K Sivakumar's recent statements stressing the need for the project. Speaking to HT, former Tamil Nadu chief minister O Panneerselvam said that he had already urged chief minister M K Stalin to build a broader unity in the state to prevent the project that would affect the rights and interests of farmers and people in the delta districts, known as the rice bowl of the state.

Tamil Nadu chapters of the BJP and Congress have declared that they will oppose the project, regardless of the conflicting views of their counterparts in Karnataka.

Citing the verdict of the Cauvery Water Disputes Tribunal and the judgment of the Supreme Court regarding Tamil Nadu's rights to the Cauvery water, he pointed out that neighbouring Karnataka has been "habitual" in not honouring the verdict and the judgement.

Located around 90 km from Bengaluru, Mekedatu is a picturesque location where the Cauvery River plunges into a stunning gorge, creating a complex riverine forest. Mekedatu means "goat's leap” in Kannada. Forming an integral part of the Cauvery Wildlife Sanctuary, Mekedatu also connects the Biligiri Ranga Hills National Park and the Male Mahadeshwara Hills tiger reserve.

The Karnataka government wants the project to resolve the drinking water shortage problem in Bengaluru and Kanakapura. Currently, Bengaluru receives 1,350 million litres per day (MLD) of Cauvery Water. By 2030, the city will need 2,285 MLD of water, a demand that the successful implementation of the Mekedatu project could meet, the state government has said.

Large-scale urbanisation has led to a significant depletion of water resources in the two cities, and the government believes that the dam reservoir project is the only solution to the cities' crisis. The Karnataka government has said that if the project is implemented, it would help increase surface water, boost the groundwater table, and ensure drinking water for wildlife, especially elephants, who are on a crucial migratory path between the Eastern and Western Ghats.

The project is estimated to cost ₹9000 crore and would involve building a 99-metre-high concrete gravity dam, spillways measuring 318 metres in length, and three underground power units. Construction would require at least 2000 tonnes of explosives. Additionally, the project would submerge the core areas of the Cauvery Wildlife Sanctuary and use rock and sand deposits from within the sanctuary.

"Regardless of the claims made by the pro-dam lobby, it is unimaginable to divert 12,345 acres of forest land, and the environmental cost would be far too high. We must be cautious to prevent another environmental disaster of huge proportions," said K. Mohanraj of the Tamil Nadu Green Movement, urging Karnataka's environmental organisations to strongly oppose the project.

A Karnataka forest department official, who asked not to be named, said that the Cauvery sanctuary is home to unique and endangered species and is a crucial elephant corridor. The official said flooding the forest land would disrupt numerous wildlife and elephant migration paths. At-risk species include the near-threatened grizzled giant squirrel, honey badgers, Deccan Mahseer fish and smooth-coated otters.

A Karnataka water resource department official said the project will involve acquiring land from Mugguru forest's watchtower and extending to the outer regions of Hanur Forest near Kollegal in the Mysuru district; Mugguru Forest is an old Veerappan hideout located at the state boundary, just 9.1 km from Mekedatu.

The reservoir, with a capacity of 67 tmc, will submerge Sangama, a nearby tourist spot near Mekedatu that attracts almost 2,000 visitors daily. It has been estimated that at least 10000 trees will be cut down. Additionally, there will be a high human cost as tribal villages, including Bommasundra, Galebore, Makivala, Kogge Doddi, Nelluru Doddi, and Sampatagere Dodd, will be submerged.

Sanjay Gubbi, a conservation biologist based in Bengaluru who has conducted extensive fieldwork in the Cauvery Wildlife Sanctuary, emphasised the need to protect endangered wildlife species and their habitats from potential construction projects. Gubbi said the sanctuary is crucial for tiger populations from BR Hills and MM Hills to roam, thereby reducing human-tiger conflicts.

Meanwhile, experts have proposed several other options to address the water crisis in Bengaluru including smaller alternative projects in different locations along the course of Cauvery.

Thamizhaga Cauvery Vivasayigal Sangam, a collective of farmers in the delta districts, is urging the Tamil Nadu government to take a firmer stand on the Mekedatu issue by writing directly to Prime Minister Narendra Modi. PR Pandian, the Sangam’s general secretary, said there would be widespread agitations across the state if Karnataka went ahead with the project despite the grave concerns raised by its neighbour.