Karnataka has identified 2,500 acres of alternative land, including forest land, to meet the forest clearance needs of the Mekedatu balancing reservoir across the Cauvery. Tamil Nadu fears the project will reduce its share of the river.

• Site: At Mekedatu (“goat’s leap”), where the Cauvery narrows into a gorge, near Kanakapura in Bengaluru South district.
• Aim: About 4.75 tmc of drinking water for Bengaluru and nearby areas, 400 MW of hydropower, and better regulation of releases to Tamil Nadu at Biligundlu.
• Land: About 5,252 hectares, of which about 4,996 would be submerged, including parts of the Cauvery Wildlife Sanctuary and reserve forest.
• Status: Karnataka submitted the Detailed Project Report to the Central Water Commission in January 2019. It still needs approval from the Cauvery Water Management Authority (CWMA) and environment and forest clearances.
• Courts: In November 2025, the Supreme Court dismissed Tamil Nadu’s challenge as premature, and in May 2026 it rejected the review petition.

• Fear of lower flows: A large reservoir upstream could let Karnataka hold back water, especially in lean years, hurting the delta districts of Thanjavur, Thiruvarur and Nagapattinam.
• Legal position: The project must respect the 2007 Tribunal Award and the 2018 Supreme Court judgment.
• Environment: Submergence of forest and wildlife sanctuary land.
• Karnataka’s case: The reservoir will help it meet its release obligations in difficult years and will benefit Tamil Nadu too.

• Federalism: The dispute tests how inter-State river issues are settled through the Authority and the courts.
• Urban water security: It reflects the rising demand of Bengaluru from a basin already under stress.
• Forests and development: The land swap shows the balance between forest conservation and projects.

• Mistrust: Between States on data and releases in a deficit year.
• Ecological cost: Loss of forest and wildlife habitat in the sanctuary.
• Compensatory land: Equivalent non-forest land does not recreate a forest, and clearances can be delayed.
• Cost and time overruns: The project has been pending since the 2019 report.

• Cauvery: Rises at Talakaveri in the Brahmagiri hills, Kodagu, and flows through Karnataka, Tamil Nadu and Puducherry to the Bay of Bengal, with Kerala a co-basin State through the Kabini.
• Tributaries: Hemavathi, Harangi, Kabini, Shimsha, Arkavathy, Bhavani, Amaravati and Noyyal.
• Cauvery Water Disputes Tribunal: Constituted in 1990, with its award in February 2007.
• Authority: The Cauvery Water Management Authority and Cauvery Water Regulation Committee were set up in June 2018.
• Article 262: Provides for adjudication of disputes over waters of inter-State rivers, under the Inter-State River Water Disputes Act, 1956.