Tamil Nadu chief minister C. Joseph Vijay on Tuesday urged Prime Minister Narendra Modi to direct the Union Jal Shakti Ministry and the Central Water Commission to reject Karnataka’s draft Detailed Project Report (DPR) for the proposed Mekedatu reservoir on the Cauvery river, saying the move violates the Cauvery Water Disputes Tribunal’s final award and the Supreme Court’s 2018 judgment.Reject Karnataka’s Mekedatu DPR, Vijay writes to Narendra ModiThe Mekedatu proposal has again brought into focus the long-running Cauvery dispute involving Karnataka, Tamil Nadu, Kerala and Puducherry over river-water sharing. With legal and political fronts active, the matter is likely to return to central agencies and the courts as the states press opposing positions.In his letter, Vijay said Karnataka’s announcement of a ‘Bhoomi Pujan’ and public statements by Karnataka deputy chief minister DK Shivakumar had caused “a lot of concern” among thousands of Tamil Nadu farmers who depend on Cauvery water. He warned that creating a new large storage reservoir is impermissible because the Cauvery basin is a deficit basin and available water at 50% dependability has already been allocated to the party states.Vijay said the Mekedatu project is not among those permitted by the tribunal and that planning new projects across the Cauvery or its tributaries, other than those specifically allowed in the tribunal’s final award as affirmed by the Supreme Court, would amount to interference with the judgment. He also noted that the Supreme Court has held that an upper riparian state should not take any action that affects scheduled deliveries to a lower riparian state, and argued that Karnataka’s proposal would violate that principle.“The public utterances of the Deputy Chief Minister of Karnataka (DK Shivakumar) to this effect, has caused a lot of concern among the lakhs of farmers of Tamil Nadu, who depend on the Cauvery river for their livelihood,” Vijay said in his letter to Modi on Tuesday.Tamil Nadu officials said Vijay has directed legal and water-management teams to take immediate measures to protect the state’s rights and safeguard farmers. The state recalled that it had filed petitions in the Supreme Court opposing Mekedatu on November 30, 2018, and June 7, 2022. According to a Tamil Nadu government release, the Supreme Court during hearings on November 13, 2025, observed the project was at a preliminary stage and said the Central Water Commission, as the expert body, should determine whether the proposal fell within the scope of earlier judicial rulings before closing the cases. Tamil Nadu later filed a review petition on December 11, 2025, which was considered in chambers and subsequently dismissed, the release said.The issue drew strong reactions in Karnataka, where the state government said it remained committed to the reservoir plan and was proceeding with required documentation. Addressing reporters, Shivakumar confirmed that the state was preparing a new DPR and would go ahead with the Mekedatu dam. “We are thankful on behalf of Karnataka, so let us take it forward. It is the duty of the Central government. We are already in the process of filing our new DPR, and we will go ahead with the Mekedatu dam,” he said.Karnataka Congress MLA Ganiga Ravikumar dismissed Tamil Nadu’s political objections and defended the project, saying preparations for the DPR were complete and that the Supreme Court had directed matters to the Cauvery Water Management Board. “We are giving the Tamil Nadu people their share of water. They do not have the right to stop us from building a dam in our place,” he said, adding that political opposition would not stop construction.Farmers’ groups in Tamil Nadu also raised the alarm. Representatives of the coordination committee of all farmers’ associations, led by PR Pandian, met state minister K.A. Sengottaiyan at the Secretariat and urged the government to seek an injunction against the Mekedatu proposal. Pandian alleged the draft DPR—reported to have been prepared and submitted by Karnataka—would threaten drinking water for some 5 crore (50 million) people across 32 districts, turn 25 lakh (2.5 million) acres of land into “desert,” and displace farmers. He called for an immediate strengthening of legal teams, an emergency lawsuit, and cancellation of any approval for the draft report that contradicts tribunal and Supreme Court verdicts.