Cauvery water row escalates as Tamil Nadu moves Supreme Court against Karnataka

The Tamil Nadu government has approached the Supreme Court seeking a direction to Karnataka to implement a Central Water Management Authority (CWMA) order of July 30, which mandated the release of 3,500 cusecs of Cauvery water daily for 15 days from the Kabini and Krishna Raja Sagara (KRS) reservoirs. The petition, filed on Monday, August 3, 2026, marks the latest legal escalation in the longstanding inter-State water dispute.

The application, finalised by senior advocates C.S. Vaidyanathan and G. Umapathy and drafted by Tushar Nair, was filed by advocate-on-record B. Karunakaran. Tamil Nadu requested the court to direct the CWMA to issue an appropriate order to Karnataka to make good the shortfall at the inter-State point of Billigundulu on a pro-rata basis for the period from June 1 to August 12. This includes an immediate release of 26.954 TMC of water and a further 4.536 TMC (at 3,500 cusecs for 15 days) on or before August 12.

Additionally, the State sought a direction to the CWMA to monitor the flows in Karnataka’s reservoirs every 10 days and ensure stipulated monthly and daily releases at Billigundulu. Tamil Nadu argued that Karnataka has consistently defied the orders of the Cauvery Tribunal, which allocated water between the two states, except on occasions when surplus flows were unavoidable due to floods.

The legal move comes amid evolving political circumstances. Karnataka Chief Minister D.K. Shivakumar had earlier stated that the water situation has become “slightly better” and urged Kannada organisations to withdraw their proposed State-wide bandh on August 13. The bandh was called by these groups to protest against the CWMA’s directive, which they argue is unfavourable to Karnataka’s farming community.

Tamil Nadu’s application noted that the CWMA reviewed the hydrometeorological conditions in the Cauvery basin on July 30 and endorsed the July 28 recommendations of the Cauvery Water Regulations Committee (CWRC) to release water from KRS and Kabini at 3,500 cusecs from July 29 for 15 days. However, the flows actually realised at Billigundulu between July 29 and August 2 ranged from 158 to 530 cusecs, far below the stipulated quantum. This, the State argued, demonstrates a wilful non-compliance by Karnataka.

The petition highlighted that Karnataka’s four major reservoirs—KRS, Kabini, Harangi, and Hemavathy—had a combined gross storage of 77.537 TMC as on August 3. Of this, KRS held 23.078 TMC, Kabini 18.610 TMC, Harangi 7.827 TMC, and Hemavathy 28.022 TMC. The State contended that this storage has increased due to recent heavy rainfall in the catchments upstream of Kabini and KRS, and that Karnataka has adequate resources to comply with the CWMA’s directions.

Tamil Nadu also presented data on rainfall deficits in the catchments. For the period from June 1 to July 27, the catchment upstream of KRS received 488.0 mm against a normal of 633.4 mm (a 23% deficit), the catchment upstream of Kabini received 676.1 mm against 1160.2 mm (42% deficit), and the uncontrolled catchment received 78.4 mm against 119.5 mm (34% deficit). These figures, the State argued, need to be considered when assessing distress.

According to the pro-rata assessment of distress as on July 28, even if Karnataka released 3,500 cusecs for 15 days, it would only provide 4.536 TMC, leaving a backlog of 5.379 TMC. Considering inflows into Karnataka’s four major reservoirs up to August 3 against the 30-year average, the pro-rata ratio works out to 46.34%. Based on this, the flows due from June 1 to August 12 amount to 26.95 TMC, significantly higher than the 4.536 TMC directed by the CWRC and CWMA.

The Supreme Court is likely to hear the petition in the coming days. Karnataka has not yet filed a formal response. The dispute over the Cauvery waters dates back to colonial times and has seen multiple judicial pronouncements, including the 2007 final award by the Cauvery Water Disputes Tribunal and the 2018 Supreme Court judgment that enhanced Tamil Nadu’s share. The current petition adds another chapter to this complex legal and political saga.