Party chief M Karunanidhi said copious rains had ensured increase in the storage level even as discharge of water for drinking needs had been stepped up considerably even as the storage had touched 138.10 ft.
"By unnecessarily discharging excess amount of water, Tamil Nadu could lose an opportunity to store water at 142 ft (as per the May 7, 2014 Supreme Court order)," he said in a letter to partymen here.
The state government should not make any delay and take appropriate steps, such as filing a caveat if Kerala moved Supreme Court, he said citing reported remarks of its Water Resources Minister PJ Joseph in this regard.
Earlier, on Tuesday, Kerala Chief Minister Oommen Chandy had said his government was examining legal options to maintain the water level at 136 ft considering the "safety aspect" though the apex court had in its May verdict held that the 120 year-old dam was safe and that water could be stored at 142 ft.