What’s the Cauvery dispute and how does the Mekedatu dam feature in it?
The long-running dispute between Karnataka and Tamil Nadu over sharing of the Cauvery river's waters has resurfaced in connection with Karnataka's proposed Mekedatu Balancing Reservoir-cum-Drinking Water Project
Tamil Nadu opposes the project, contending it would reduce the natural downstream flow of the Cauvery and violate the existing tribunal award and Supreme Court judgment on water sharing
Karnataka maintains the project is meant only to store surplus monsoon floodwater for drinking-water supply to the Bengaluru region and hydropower generation, without affecting Tamil Nadu's allocated share
Courts have so far treated legal challenges to the project as premature, pending formal approval of its Detailed Project Report, while reaffirming that Karnataka remains bound by the existing water-sharing arrangement regardless of the project's fate
Cauvery Water Disputes Tribunal (1990) and the 2007 Final Award
The Cauvery Water Disputes Tribunal (CWDT) was constituted in 1990 by the Union Government under the Inter-State River Water Disputes Act, 1956, to adjudicate the sharing of Cauvery waters among the riparian states after decades of unresolved negotiation dating back to colonial-era agreements (1892 and 1924).
Key Details
- The Tribunal delivered its final award in February 2007, allocating the assessed 740 TMC (thousand million cubic feet) of available water as: Tamil Nadu 419 TMC, Karnataka 270 TMC, Kerala 30 TMC, and Puducherry 7 TMC, with additional reservations for environmental protection and outflow to the sea
- The award followed 17 years of proceedings, illustrating the chronic delays associated with the tribunal mechanism for inter-state river disputes generally
- Riparian states involved: Karnataka and Tamil Nadu (major upper and lower riparian states respectively), with Kerala and Puducherry as smaller stakeholders
Tamil Nadu's objection to the Mekedatu project is framed as a violation of this 2007 tribunal award, since any new upstream storage structure could alter the flow pattern the award was designed to guarantee downstream.
Supreme Court's 2018 Judgment — Modification and the Cauvery Water Management Authority
In 2018, the Supreme Court, while hearing appeals against the CWDT's 2007 award, upheld the broad tribunal framework but revised the specific allocation to account for Bengaluru's growing drinking-water needs and groundwater usage by Karnataka, and directed the creation of an institutional mechanism to supervise implementation.
Key Details
- Revised allocation under the 2018 judgment: Tamil Nadu 404.25 TMC, Karnataka 284.75 TMC, Kerala 30 TMC, Puducherry 7 TMC (Karnataka's share increased by about 14.75 TMC relative to 2007, largely offset by a reduction to Tamil Nadu)
- The Supreme Court directed constitution of the Cauvery Water Management Authority (CWMA) as the body responsible for regulating storage, water release schedules, and monitoring compliance by the states, replacing the earlier temporary supervisory arrangements
- The Court described the Cauvery as a "national asset," reinforcing the principle that inter-state rivers cannot be treated as the exclusive property of the state in which they originate or predominantly flow
Karnataka's position that Mekedatu will not affect Tamil Nadu's share is tested against this 2018-revised allocation and the CWMA's regulatory oversight, which continues to govern actual water releases regardless of any new reservoir.
Article 262 and the Inter-State River Water Disputes Act, 1956
Article 262 of the Constitution empowers Parliament to provide for adjudication of inter-state river water disputes and to bar the jurisdiction of the Supreme Court or any other court over such disputes; Parliament has exercised this through the Inter-State River Water Disputes Act, 1956 (providing for tribunals) and the River Boards Act, 1956 (providing for advisory river boards).
Key Details
- Despite the jurisdictional bar under the 1956 Act, the Supreme Court has continued to hear Cauvery-related matters by invoking its special leave (Article 136) and complete-justice (Article 142) powers, as it did in deciding the 2018 appeal
- The doctrine that an upstream riparian state generally requires the interests of downstream states to be safeguarded before undertaking new water-diversion or storage works on a shared inter-state river has informed judicial scrutiny of similar upstream project disputes
- Inter-state water disputes are a recurring Centre-State/State-State federalism theme distinct from Centre-State legislative disputes under the Seventh Schedule, since "water" is a State List subject (Entry 17) but inter-state rivers fall under Union jurisdiction via Entry 56 of the Union List and Article 262
The Mekedatu dispute is a live illustration of how a subject nominally in the State List (water) becomes a matter of Union-level tribunal and Supreme Court adjudication once an inter-state river is involved.
Mekedatu Balancing Reservoir-cum-Drinking Water Project
The Mekedatu project is a proposed multipurpose dam by Karnataka at the confluence of the Cauvery river and its tributary, the Arkavathi, near Kanakapura in Ramanagara district, close to the Karnataka-Tamil Nadu border and roughly 90 km from Bengaluru.
Key Details
- Proposed as a concrete gravity dam approximately 99 metres high and 735 metres long, with an underground powerhouse
- Designed storage capacity of roughly 67 TMC of water, intended to supply drinking water to the Bengaluru metropolitan region and generate about 400 MW of hydroelectric power
- Estimated project cost is in the range of Rs 9,000 crore; the project would submerge several thousand hectares of land, a large share of it forest land, raising additional forest-clearance and environmental-clearance requirements under the Forest (Conservation) Act, 1980 and the Environment (Protection) Act, 1986
The project's location just upstream of Tamil Nadu, combined with its large storage capacity, is the technical basis for Tamil Nadu's apprehension that it could alter the timing and volume of flow guaranteed under the tribunal award and the 2018 Supreme Court judgment.
- Cauvery Water Disputes Tribunal constituted: 1990, under the Inter-State River Water Disputes Act, 1956; final award: February 2007
- 2007 award allocation (of 740 TMC): Tamil Nadu 419 TMC, Karnataka 270 TMC, Kerala 30 TMC, Puducherry 7 TMC
- 2018 Supreme Court-revised allocation: Tamil Nadu 404.25 TMC, Karnataka 284.75 TMC, Kerala 30 TMC, Puducherry 7 TMC
- Institutional mechanism created in 2018: Cauvery Water Management Authority (CWMA)
- Mekedatu project: ~99 m high, 735 m long dam; ~67 TMC storage capacity; ~400 MW hydropower; estimated cost ~Rs 9,000 crore
- Constitutional basis for inter-state river adjudication: Article 262; statutory basis: Inter-State River Water Disputes Act, 1956 and River Boards Act, 1956