Why Tamil Nadu and Karnataka are sparring over Cauvery water? | Explained

The story so far: The eight-year-old Cauvery Water Management Authority (CWMA) is holding its 53rd meeting in New Delhi on Wednesday (July 22, 2026) amid an extremely poor southwest monsoon (June-September) in many parts of southern States, especially catchment of the Cauvery river. The two principal riparian States — Karnataka and Tamil Nadu — are expected to present their point forcefully at tomorrow’s meeting, as they have been reeling under the impact of an adverse monsoon.

How did the CWMA come into being?

Established on June 1, 2018, the Authority was constituted as an implementation mechanism for the Supreme Court’s (SC) 2018 judgment and the final award of the Cauvery Water Disputes Tribunal (CWDT) of 2007. The key aspect of the judgment pertains to water allocation among the constituents of the Cauvery basin.

Holding on to the total availability of water, 740 thousand million cubic (tmc) feet, in the basin during a normal year, as determined by the CWDT, the Court made the allocation for the constituents as follows: Puducherry (7 tmc ft); Kerala (30 tmc ft); Karnataka (284.75 tmc ft) and Tamil Nadu (404.25 tmc ft). Additionally, 10 tmc ft and 4 tmc ft were set aside for environmental protection and inevitable escapages into the sea.

In the case of Karnataka, the Court allocated 4.75 tmc ft specifically to Bengaluru, which, it referred to as having attained “global status,” and the city’s drinking water requirement had risen multifold. Besides, the Court reduced Tamil Nadu’s original share, which was fixed by the Tribunal in the final order at 192 tmc ft, by 10 tmc ft and transferred that quantity to Karnataka. As a result, Karnataka’ share, which was determined by the CWDT as 270 tmc ft, increased by 14.75 tmc ft.

One of the salient features of the Court’s verdict pertains to Karnataka’s commitment to Tamil Nadu. The upper riparian State is to ensure, at Biligundulu, located on the inter-State border, 177.25 tmc ft, as per a monthly schedule that is divided into blocks of 10 days each. Of this quantity, 123.14 tmc ft is to be provided during the period from June to September, also marks the monsoon. Invariably, it is during this period that the Cauvery issue flares up in times of poor rainfall, as has happened now.

How is the CWMA functioning?

The Authority, headed by a full-time chairman, has two whole-time members dealing with water resources and agriculture. It consists of two part-time members drawn from the Union Ministries of Jal Shakti and Agriculture, apart from representatives of the four constituents of the basin. The Member-Secretary of the Authority is the chief of the Cauvery Water Regulation Committee (CWRC), which assists the CWMA in arriving at decisions. The Committee includes, among others, a representative of the Meteorological Department.

The CWRC is required to meet once every ten days in June and October, and after the onset of the southwest and northeast monsoons, the frequency is at least once a fortnight. As for the Authority, there is no specific stipulation, but it invariably meets at the beginning of the water year (June-May) to determine the total residual storage in eight specified reservoirs and order water releases.. It meets as and when required. Ordinarily, the CWMA’s meetings are preceded by meetings of the CWRC. Last week, the Regulation Committee held its deliberations. During the current water year, the Authority met once in June.

What is the situation with regard to rainfall in the Cauvery catchment and storage in reservoirs?

Between June 1 and July 21, Karnataka, the upper riparian State that has four reservoirs in the basin, experienced a 28% deficit in rainfall, according to a report from the Meteorological Department. The situation in southern interior Karnataka, where the catchment of the Cauvery River lies, is worse, with a deficit of 36%. Kodagu, where the river originates, recorded a deficit of 37%. The plight in Wayanad, Kerala, the catchment area for the Kabini River (one of the tributaries of the Cauvery), is much worse, with a deficit of 61%.

The combined storage of Karnataka’s four reservoirs — Krishnaraja Sagara, Kabini, Hemavathy and Harangi — stood at 59.49 tmc ft on the morning of July 21, against a total capacity of 114.57 tmc ft, according to data released by the Karnataka State Natural Disaster Monitoring Centre. Since June 1, the four reservoirs have received about 32.4 tmc ft, while they have released 5.5 tmc ft.

As regards Tamil Nadu, the Mettur dam, regarded by farmers in the Cauvery delta as their lifeline, had a storage of 36.9 tmc ft (capacity: 93.4 tmc ft) on July 21. Biligundulu, from June 1 to July 19, accumulated about 3.4 tmc ft against the stipulated 28.3 tmc ft for the period in question, leaving a shortfall of 24.9 tmc ft.

On July 3, Karnataka Chief Minister D.K. Shivakumar made it clear that water from major reservoirs would not be released to irrigate crops until the situation improved. In Tamil Nadu, authorities did not commence the water release from Mettur on the scheduled date of June 12 for irrigation in the delta during the ongoing Kuruvai cultivation season.

What is the arrangement for distress sharing?

There is no scientific study that forms the basis for the Authority’s decisions regarding distress sharing. About 20 years ago, attempts were made to arrive at a consensus on a formula, but differences over the choice of parameters have eluded a solution. Only in 2023, out of the last eight years, was the Authority’s efficacy put to the test. The CWMA had followed the principle of proportionate reduction as prescribed by the Tribunal and the Supreme Court, but this did not satisfy both the principal States.

The Union Ministry of Jal Shakti’s order (para 10.3) of June 2018, which provided for the constitution of the Authority, states that “the Authority, through the Regulation Committee and with the help of the Central Water Commission, and other Central or State organisations as necessary, will identify situations of distress in the river basin.” Additionally, the order stipulates that “in case of deficiency in water availability during any month, as reported by the Regulation Committee, the Authority will consider a reduction in the indent of the parties in proportion to the quantities allocated to each State by the Tribunal, as modified by the Supreme Court for the designated crops. The Regulation Committee shall monitor the actual performance of the monsoon at ten-day intervals and report to the Authority, indicating the extent of variation from the normal. The Authority, on receipt of such information, will consider any changes to the release ordered by them earlier,” the communication points out, adding that “a similar exercise will continue as the monsoon progresses during the succeeding months until the end of the water year [May 31].”

What can be done to promote a better understanding of the situation among farmers and other sections of society in the two principal States?

At present, there are no non-official members in the CWRC or the CWMA. There is a provision in the Union Ministry’s order [para 6 (b)] for the Authority to co-opt the services of experts from Universities and other institutions by treating them as special invitees for its meetings. The Union government or the CWMA can also follow the example of the Chennai Metropolitan Water Supply and Sewerage Board, which once had six non-official directors chosen from different fields. In addition to environmental specialists, representatives of farmers can be included by the Authority. Besides, the minutes of the deliberations of the CWRC and the CWMA should be published on a dedicated website for the Authority as early as possible.