Chennai: The heavy outflow of 70,000 cusecs from Mettur reservoir has brought jubilation among the farmers in the delta districts. The water level crossed the full-reservoir level of 120 ft and stood at 121 ft on Monday. Nine Cauvery basin districts have been sounded flood alert since September 7. People have been advised not to take bath in the river and those living in low-lying areas have been shifted to rescue shelters.

The reservoir has 94.926 tmc ft water. It can take another three ft of water, but for safety reasons, public works department (PWD) has been releasing more than the inflow (66,000) through various systems. While 1,000 cusecs is being diverted for drinking water supply, another 900 cusecs is being released into canals. It may, however, be a cause of concern for water managers, for, much of the water released into the Cauvery would get wasted as run off into the Bay of Bengal. Water from the Cauvery, Vennaru and their various irrigation systems had started flowing into the sea almost a fortnight ago.

The water that gushed out of Mettur on Monday, if fully tapped, would have sufficed to quench the thirst of Chennai city for more than six months. Tamil Nadu is paying the price for not having major water storage systems downstream of Mettur. It hasn’t done enough to divert water to scores of smaller water-harvesting structures like lakes and tanks. Diversion of the Cauvery water to parched regions of Ramanathapuram and Sivaganga districts would have helped promote agrarian economy in those regions.

Various structures like Mayanur Barrage in Karur district, Upper Anaicut at Mukkombu in Trichy district, Grand Anaicut and Lower Anaicut in Thanjavur district are water diversion and regulation structures without much holding capacity. Veeranam lake, which supplies drinking water to Chennai is the only storage facility downstream, but its holding capacity is just 1.3 tmc ft. The state government has announced construction of four more barrages in the delta region – two each in Thanjavur and Nagapattinam districts.

As per official estimates, the delta districts of Thanjavur, Tiruvarur and Nagapattinam require only 22,000 cusecs for carrying out Samba cultivation. Normally, only 25,000 cusecs is released from Grand Anaicut for irrigation, which also includes some amount of run off. “Our release is almost three times the requirement of the Cauvery delta, but we do not have any alternative. We have kept all the 16 shutters half open,” said a PWD official. Officials managing the dam are informing details of water release on an hourly basis to the collectors of all the districts in the Cauvery basin. PWD chief engineer A Jayagopal said the shutters would be fully opened to release more water if the inflow increases in the coming days.

This is the 43rd year that Mettur dam is reaching its full level. Last year too, the dam had reached its full level.

(With inputs from V Senthil Kumaran and D Vincent Arockiaraj)

