CHENNAI: It is no longer a water war for sustaining irrigation. The Tamil Nadu-Karnataka Cauvery water dispute has escalated to a new level. The fight now is for potable water for Chennai and Bengaluru, two southern cities that have been rapidly expanding due to the increasing migrant population. Chennai gets nearly 2tmcft of Cauvery water every year through the Veeranam project. Daily supply of Cauvery quenches the thirst of half of Bengaluru’s population. Karnataka, which is going to polls in a couple of months, petitioned the Supreme Court for 12tmcft for Bengaluru city, an allocation that did not find mention in the Cauvery Water Disputes Tribunal’s final award.The Cauvery is the lifeline for Tamil Nadu, contributing 50% of the total surface flow in all rivers and river courses in the state. In Tamil Nadu, Stanley reservoir in Mettur is the only major dam across the river. Cauvery delta is one of the oldest and largest in the country. It supplies drinking water to 1.7 crore people, approximately 20% of the total population of the state. The wells sunk along the Cauvery bed sustain 127 combined water supply schemes that cater to 19 of the 32 districts. Schemes in the pipeline suggest that Erode, Vellore and Tiruvannamalai districts too will get Cauvery water. From Hogenakkal in western Dharmapuri district to Ramanathapurm in the south, Tamil Nadu Water Supply and Drainage Board supplies 1,200 million litres a day from the sub-surface of Cauvery basin. Even Dindigul corporation gets partial supply from the Cauvery.The Centre recommends a daily per capita consumption of 135 litres of water. Karnataka has sought modification of the monthly supply pattern for Tamil Nadu in June and July and for reopening the adjudication made by the tribunal to guarantee supply to Bengaluru city. “It will be a travesty of justice if the tribunal’s award is overturned and an ad hoc increase is awarded to one state based on drinking water needs just because the state failed to manage its water resources,” said a senior TN bureaucrat, closely monitoring the dispute. “All the years of work put in by professional assessors in the tribunal will come to nought,” he said. Further reduction in water supply to Tamil Nadu during the summer months may pose a serious challenge, given the erratic monsoon.Karnataka too has been grappling with dwindling water bodies of Bengaluru for the last four decades and the requirements of the IT hub’s burgeoning population. Going by chief minister Siddaramaiah’s statement in the past, it is not just Bengaluru, but even Mysuru and Mandya towns and 600 villages are dependent on Cauvery water. Every year the city of Bengaluru draws 29tmcft of water from the Cauvery and the demand is on the rise. Tamil Nadu PWD former chief engineer R Veerapan said the apportioning by the tribunal, 270tmcft for Karnataka and 419tmcft for Tamil Nadu, included drinking water as well. After obtaining the opinion of expert panels, the tribunal awarded the final order in 2007, 17 years after it was constituted. The award was notified by the Centre in 2013.