State of Karnataka v. State of Tamil Nadu
Background
For over a century, Karnataka (formerly Mysore) and Tamil Nadu (formerly Madras), along with Kerala and the Union Territory of Puducherry, had disputed how to share the waters of the river Cauvery, going back to agreements signed in 1892 and 1924 between the British-era Madras Presidency and the princely State of Mysore. After decades of failed negotiations, the dispute was referred in 1990 to the Cauvery Water Disputes Tribunal, which delivered its final award in 2007 allocating specific shares of water to each State. All four parties (Karnataka, Tamil Nadu, Kerala, and Puducherry) filed civil appeals before the Supreme Court challenging different aspects of that award, including the validity of the old agreements, how much water each State should get for irrigation, drinking water, and industrial use, and how the sharing should be implemented and monitored.
Decision Breakdown
The Supreme Court held that the 1892 and 1924 agreements were not invalid or "unconscionable," but that the 1924 agreement's binding force had lapsed in 1974 after its stipulated 50-year review period. The Court affirmed the Tribunal's use of the international "principle of equitable apportionment" (drawn from the Helsinki Rules and similar international water-sharing norms) rather than any historical or "natural flow" entitlement, and largely upheld the Tribunal's findings on irrigated areas and crop-water needs for each State. However, it revised the final shares: Karnataka's allocation was increased from 270 to 284.75 TMC (thousand million cubic feet), crediting it with an additional 10 TMC for groundwater available to Tamil Nadu and 4.75 TMC for the full drinking-water needs of Bengaluru city (not just the one-third falling within the river basin), while Tamil Nadu's share was correspondingly reduced from 419 to 404.25 TMC. Kerala's 30 TMC and Puducherry's 7 TMC allocations, along with 10 TMC for environmental protection and 4 TMC for unavoidable outflow to the sea, were left undisturbed, keeping the total at 740 TMC. The Court also directed the Central Government to frame an implementation scheme (a "Cauvery Water Management Authority") under Section 6A of the Inter-State Water Disputes Act within six weeks to enforce the revised monthly release schedule.
Lesson Learnt
Water from a river flowing through multiple States is treated as a shared national resource to be divided on principles of fairness and actual need (drinking water first, then irrigation, then industry) rather than on whoever happens to be the upper or lower riparian State or on old colonial-era agreements being treated as permanently fixed; and ordinary citizens' basic needs, like a city's drinking water supply, can outweigh rigid geographic boundaries like "river basin" lines when courts decide how to split such a scarce resource.