Tamil Nadu has reiterated to the Cauvery Water Management Authority (CWMA) that its demand for the clearance of backlog in Cauvery water realisation – around 16 TMC – is based on the principle of pro-rata share in the flows actually realised. 

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

In its communication sent recently to the CWMA and the Cauvery Water Regulation Committee (CWRC), the State government had mentioned “its demand is not based on predicted future flows. Tamil Nadu is seeking only its pro-rata share in the flows actually realised up to the date of recovering, during the distress period, together with the backlog already accumulated.” 

After sending the communication, the State government filed an application in the Supreme Court last week too, seeking the direction to Karnataka for making good the shortfall in the realisation of the Cauvery water from June 1 to September 9. The CWRC and the CWMA are to hold their deliberations on September 24.   

Contending its backlog, as on September 7 (the day before the last meeting of the CWRC and the CWMA), was about 16 thousand million cubic feet (tmc ft), Tamil Nadu argued that instead of 6,000 cusecs at Biligundulu for the next 15 days, the Authority should have ordered Karnataka to ensure the realisation of about 20,370 cusecs (equivalent to about 1.76 tmc ft a day) on the inter-State border. It also felt the CWMA’s failure in ensuring release of the backlog of over 16 TMC as on September 23 would “seriously prejudice the irrigation and would affect the entire agricultural operations [in Tamil Nadu]. This would seriously affect the interests of the farmers’ their 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 the Cauvery delta of Tamil Nadu, only 12,000 cusecs was being released and the supply had to be sustained for 45 days and “for that, around 55 to 60 TMC is required to be released. But, the available storage in Mettur after reserving for drinking, evaporation and environment needs, as on September 8 was only 40 tmc ft.  

As on September 21, the storage of Mettur stood at 46.95 tmc ft. Applying the requirements  for other needs, the quantity of water available for irrigation as on date was effectively 34 tmc ft. Assuming nil addition and the discharge at one tmc ft a day, the current storage would last 34 days.   

As for the rainfall pattern during the north-east monsoon, the State added the monsoon, being “erratic, uneven or even deficient,” could  not be “predicted with certainty at this stage.“  So, “it cannot be presumed that Tamil Nadu will necessarily derive the anticipated benefit” from the monsoon. Besides, the present requirement of the State “cannot be deferred on the assumption of future rainfall.”