Karnataka in the Supreme Court of India on Thursday (August 13, 2026) said good rainfall in a distress year made right an erroneous direction upheld by the Cauvery Water Management Authority (CWMA) to daily supply Tamil Nadu with 3,500 cusecs of water at the inter-State border Biligundlu till August 12.

Karnataka said it was fortunately able to overcome the challenges of a distress year and worsening El Niño conditions to ensure the supply of water from its Kabini reservoir due to large inflows owing to good rainfall in the Wayanad area above the Kabini catchment, which lies in Kerala.

“The releases from the KRS and Kabini reservoirs have already been reflected at the inter-State border at Biligundlu. From July 29 to August 10, Karnataka has released 1,64,080 cusecs from its reservoirs, and after a time lag of two days, the flows have reached the inter-state border at Biligundlu, as measured by the Central Water Commission gauge station,” Karnataka, represented by senior advocate Mohan V. Katarki, said.

Karnataka said that, in total, from July 29 to August 10, it has ensured 86,797 cusecs at the inter-State border at Biligundlu, as against 45,500 cusecs expected to be ensured as per the 9th recommendation of the CWRC upheld by the CWMA. The State said the decision of the CWMA was “undoubtedly complied with”.

However, Tamil Nadu has filed an additional affidavit in the Supreme Court on Thursday (August 13, 2026), arguing that Karnataka’s release of water was “never voluntary compliance”.

The storage in the KRS reservoir increased from 17.039 TMC on July 28 to 30.904 TMC on August 11, against its full capacity of 18.716. Harangi reservoir is 97.13 % full, and Hemavathy reservoir is 86.69 % full. Its total storage is 77.61% of the full capacity of 111.493 TMC. Karnataka failed to release water to Tamil Nadu even on a pro rata basis. The releases were not voluntary compliance, but due to spillage, water was let down to Billigundulu. Thus, it is seen that Karnataka did not release water till its Kabini reservoir was nearly full,” Tamil Nadu, represented by senior advocate G. Umapathy, countered Karnataka.

Tamil Nadu maintained that only 19.49% of the allocated Cauvery water has been realised from Karnataka.

It said Tamil Nadu had flagged a substantial backlog of 21.357 TMC by August 12. The State further said the quantity due on a pro rata basis from August 12 to August 31 was 37 TMC.

Distress and dispute: On Karnataka, Tamil Nadu and the Cauvery

However, CWMA has only directed Karnataka to supply only 15.552 TMC from August 12 for a period of 15 days.

Tamil Nadu sought the court to direct Karnataka to release the balance quantity of 21.357 TMC due as of August 12. It has also sought the release of 37 TMC of Cauvery water from August 12 to August 31.