With CM Vijay opening the Mettur dam, focus turns to longevity of water release

On September 1, 2026, Tamil Nadu Chief Minister C. Joseph Vijay inaugurated the Mettur dam for irrigation purposes. The government intends to maintain the water release for an initial period of 45 days. As of Tuesday, the water level stood at 91.56 ft with a storage capacity of approximately 54.45 thousand million cubic feet (tmc ft).

The dam's full level is 120 ft, and its capacity is 93.47 tmc ft. Authorities plan to release 1 tmc ft of water daily. Assuming the worst-case scenario where the state does not receive any further inflow, they can sustain the release for around one and a half months, accounting for 10 tmc ft for environmental flows, drinking water requirements, and dead storage.

The northeast monsoon, expected to begin around October 20, will provide a significant portion of the state's annual rainfall. However, there is a seven-day deviation window for its onset. Karnataka has released more water than initially stipulated during July-September 2026, leading to a surplus of nearly 20 tmc ft that can potentially flow from Karnataka in the following 30 days.

With this additional water, authorities can extend the release period by two weeks. In the worst-case scenario of minimal water realisation in September, the state might only receive around 10 tmc ft, similar to realisations in 1987 and 2003-04. The release was initiated on Tuesday to ensure timely water availability for the Samba cultivation season, as delayed water could adversely impact crops.