Tamil Nadu explains to Cauvery Authority the reasons behind its demand to clear the pending 16 tmc feet

The state pointed out that against the normal release of 15,000 cusecs to 18,000 cusecs per day, only 12,000 cusecs was being released from the Mettur dam for irrigation in the Cauvery delta.

Tamil Nadu has reiterated the Cauvery Water Management Authority (CWMA) that its demand to clear the Cauvery water realization backlog – around 16 TMC – is based on the principle of pro rata share of flows actually realized.

The concept of pro rata assumes importance in the light of the Cauvery Water Disputes Tribunal and the Supreme Court which referred it for adoption in times of emergency.

In its communication sent recently to the CWMA and the Cauvery Water Regulation Committee (CWRC), the state government said “its demand is not based on projected future flows. Tamil Nadu is only seeking its proportionate share of the flows actually realized up to the date of restoration, during the emergency period, along with the already accumulated backlog.”

After sending the notice, the state government also filed a petition in the Supreme Court last week seeking direction to Karnataka to rectify the lapse in Cauvery water realization from June 1 to September 9. The CWRC and CWMA are scheduled to meet on September 24.

Tamil Nadu, grappling with its backlog of about 16,000 million cubic feet (tmc ft) on September 7 (a day before the last CWRC and CWMA meeting), claimed that instead of 6,000 cusecs at Biligundul for the next 15 days, the authority should have directed Karnataka to ensure the realization of about 20.37 tmc ft (1.76 tmc ft per day) at the interstate border. It also opined that CWMA’s failure to ensure the release of the backlog of over 16 TMC on September 23 would “seriously damage irrigation and affect the entire agricultural operations (in Tamil Nadu). This would seriously affect the interests of their farmer families and the agricultural economy of the state.”

The state also pointed out that against the normal release of 15,000 cubic feet per second (cusecs) to 18,000 cusecs per day from the Mettur dam for irrigation in Tamil Nadu’s Cauvery delta, only 12,000 cusecs was released and the stock had to be maintained for 45 days to release about 5.6 TMC. But the available storage at Mettur after provision for potable, evaporation and environmental needs as on 8 September was only 40 tmc ft.

As of September 21, Mettur’s inventory stood at 46.95 tmc ft. Applying the requirements to other needs, the amount of water available for irrigation as on date was effectively 34 tmc ft. Assuming zero addition and discharge of 1 tmc ft per day, current storage would last 34 days.

Regarding the rainfall pattern during the northeast monsoon, the state added the monsoon as it is “erratic, patchy or even deficient” cannot be “predicted with certainty at this stage”. So, “it cannot be assumed that Tamil Nadu will necessarily get the expected benefit” from the monsoon. Additionally, the state’s current requirement “cannot be delayed in anticipation of future rainfall.”

Published – 22 Sep 2026 0:24 IST