The Case for the RasiManal Joint Project in the Cauvery River: Some Reflections

The Case for the RasiManal Joint Project in the Cauvery River: Some Reflections

1. This year, 2026, is an El Niño year, which will be hotter and drier. I updated this blog on 26 September 2026. Most of the dams in Karnataka are not full. The water levels do not correspond to the water levels recorded during the last few years. This year is undoubtedly a deficit year. The KRS, which is the most important reservoir in Karnataka in the Cauvery basin, is not full. Many of the tributaries of the Cauvery located in Karnataka have their own dams. Some of them have comfortable storage capacity, though by no means can this be described as full capacity. There is one more monsoon to come. Hopefully, the North East Monsoon will make up for much of the deficit experienced during the southwest monsoon. Mercifully, the political temperature levels in these two states and mutual hostility did not rise as much as they did in previous deficit years. One must also give credit to the statesmanship of the respective leaders of both Tamil Nadu and Karnataka.

2. Earlier, I had noticed that whenever there was a serious dispute relating to the sharing of waters between these two states, public transport between the two states would be disrupted. Even private transport was difficult. The buses of one state would normally not venture into the other state when the dispute was simmering. But this year, despite the non-compliance with the orders passed by the Tribunal and the Supreme Court, the situation did not escalate beyond acceptable limits. In a way, business is as usual.

In fact, for the first time, we had the Chief Minister of Karnataka telling his people: “Look here, we are bound to release water in accordance with Indian law and the Constitution because these are the orders of a legitimate constitutional body.” But that had not stopped him from requesting the Supreme Court to increase Karnataka’s State water quota in view of water scarcity. The Supreme Court has refused this request. That itself is a significant step forward. For that reason, the Chief Minister of Karnataka deserves warm congratulations. Hopefully, the statesmanship shown by the Karnataka Chief Minister will also be reciprocated by the Chief Minister of Tamil Nadu.

3. A Brief Historical Background

Let us understand a little bit of the post-independence history. In 2007, the Cauvery Water Disputes Tribunal passed its Final Award. It computed the average dependable yield of the Cauvery River at 740 TMC. The river originates in Karnataka. However, a substantial portion of the Cauvery basin is located in Tamil Nadu. Taking into account various relevant geological, hydrological, political and legal factors, the Tribunal determined the allocation of water on the basis of the Average dependable Yield. Under the Tribunal's award, Tamil Nadu was allocated 419 TMC, Karnataka 270 TMC, Kerala 30 TMC, and Puducherry 7 TMC. The Tribunal has obliged Karnataka to release to Tamil Nadu about 180 TMC for the period June to February. This Quantum would be measured at Biligundlu. It releases water in the past; Karnataka released water only when the KRS was full. The Tribunal has fixed the July & August quotas. This quotes are very crucial for Tamil Nadu as the forming operations in delta will have to commenced on time. Invariably, during the deficit years, Karnataka has violated tribunal orders on timely release.

Later, in 2018, the Supreme Court, at the instance of the Government of Karnataka, modified the allocation. Tamil Nadu's share was reduced to 404.25 TMC, while Karnataka's share was increased to 284.75 TMC. More specifically, Bengaluru was assured an additional allocation of 4.75 TMC for drinking-water purposes.

4. The governments in the two states are presently led by non-BJP political parties. In fact, the Congress Party is one of the alliance partners of the party presently ruling Tamil Nadu. In this connection, we should look at some of the pending and much-discussed dam projects on the Cauvery River and the reaction of political parties to this dispute. BJP, as a party, has been more responsive to the aspirations of the state of Karnataka more, as it has a realistic chance of coming to power in Karnataka. In Tamil Nadu, BJP does not have any such chance. The situation of Congress is no different. Thus, neither of the national mainstream parties have been sympathetic even to the legitimate demands of TN.

As I have already mentioned, this year is a deficit year. It is also being described as an El Niño year. I have personally witnessed at least two El Niño phenomena. I am about 69 years old; it is my experience that whenever there is El Niño, the water deficit in the region can extend for a period of at least two to three years. A great deal of historical information about water levels in the Indian subcontinent during El Niño years is available in the public domain. We should learn from these experiences. In between, there have also been several years of surplus rainfall. There have been times when the availability of water in the Cauvery, during a plentiful year, exceeded even 1,000 TMC. Hence, both Karnataka and TN will be well within their rights to increase the storage capacity of the States within their territories.

For this purpose, the State of Karnataka has proposed the Mekedatu Project. The Mekedatu Project is being implemented by the Cauvery Niravari Nigam Limited, a State Government company of Karnataka. The company has prepared a pre-feasibility report.

According to the project report, the following technical information about the project is available online. The project is primarily conceived as a hydroelectric project. The power generation capacity is expected to be approximately 400 MW. The proposal contemplates three units of 120 MW each and an additional 40 MW underground power station, making a total installed capacity of approximately 400 MW. The total estimated water-storage capacity of the project is approximately 67.14 TMC. The project is also intended to provide approximately 4.75 TMC of water for the drinking-water requirements of Bengaluru. For completing the project, the State requires approximately 5,268 acres of land, of which a substantial portion falls within the Cauvery Wildlife Sanctuary. Predictably, the decision of the Karnataka Government was challenged in the Supreme Court. The Supreme Court directed the Union Government to consider the Karnataka Government's plea of permitting of ongoing preliminary works prior to the construction of the actual Dam. Union Government has permitted the feasibility study so that the main request for dam construction can be considered on merits in future.

The proposed Mekedatu site is located at a considerable distance from the KRS reservoir. Mekedatu is approximately 127 km from KRS, while the distance between Kabini Dam and Mekedatu is about 175 km. Thus, the independent catchment area of Mekedatu is expected to contribute a substantial quantity of water to the reservoir. The project cost is estimated at approximately ₹9,000 crore, and the proposed submergence area is approximately 106 square miles. Megadatu has a hilly terrain and is a biodiversity-sensitive region. Locating such huge reservoirs on such terrain may be fraught with other Ecological/seismic risks. The clearance from the Ministry of Environment will not be a cakewalk. The situation will be a problem. Costs and time overruns can make the project unviable. Since the final decision on merits has not yet been taken by the Union Government, there will be delay due to litigation.

5. Rasimanal Project

The State of Tamil Nadu, under the able leadership of late Kama. Raj, laid the foundation stone for a dam at Rasimanal, across the River Cauvery, in 1961. This place is about 24 km from the Karnataka border, but is located in Tamil Nadu. Its storage capacity will be 66 TMC, with a hydroelectric potential of 360 MW. This place will be less than 90 km from Bangalore. The terrain at Rasimanal is not so ecologically sensitive as Mekedatu, as the latter would involve substantial submergence in the Kaveri Wildlife Sanctuary. Even the Rasimanal Project will result in substantial submergence of agricultural land, one-third of which will be in the State of Karnataka. So, if Karnataka is assured of at least 50% of the hydropower, drinking water for Bangalore, and also water for those Karnataka farmers whose lands are in the vicinity of the submergence area, then a joint project between the States of Karnataka and Tamil Nadu will substantially achieve the objectives of Karnataka regarding the Mekedatu Project. The retired Chief Engineer of Tamil Nadu has recently written to the Tamil Nadu Chief Minister, Mr. Joseph Vijay, requesting him to take up the matter with his Karnataka counterpart. If the joint project is proposed, the Ministry of Environment will have much less objection than it would have to the Mekedatu Project. It will be a good confidence-building measure between these two States. One hopes that the Union Government, Cauvery Water Authority and the states of Karnataka and Tamil Nadu will consider these suggestions in the interest of Indian federalism and national integration.