Mettur dam customary opening on June 12 unlikely as storage remains low

Tamil Nadu faces uncertainty over opening Mettur Dam on June 12 for kuruvai irrigation due to low storage and weak monsoon forecast. Current levels may irrigate only 2.5 lakh acres, prompting government aid plans and advice to shift toward pulses

Chennai: The prospects of opening the Mettur Dam on the customary date of June 12 for the commencement of kuruvai irrigation in Tamil Nadu’s Cauvery delta appear increasingly uncertain, owing to inadequate water storage and an unfavourable southwest monsoon forecast.

Senior government officials indicated that the current storage level in the Mettur reservoir is far from adequate to support the traditional June 12 release.

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With the India Meteorological Department (IMD) forecasting a delayed onset of the southwest monsoon and revising its rainfall projection to 90 per cent of the long-period average, concerns over water availability have intensified.

As of Saturday, the Mettur Dam held around 41 thousand million cubic feet (tmcft) of water against its full storage capacity of 93.47 tmcft.

The reservoir was receiving an inflow of approximately 1,950 cusecs, while around 1,000 cusecs was being released downstream. The situation upstream in Karnataka is also far from encouraging.

According to data from the Karnataka State Natural Disaster Monitoring Centre, the combined storage in the Krishnaraja Sagar (KRS) and Kabini reservoirs stood at just 16.09 tmcft against a total capacity of 68.97 tmcft. The Harangi and Hemavathy reservoirs together stored 17.75 tmcft against their combined capacity of 45.6 tmcft.

Despite the present concerns, Tamil Nadu has already received about 330 tmcft of Cauvery water at Biligundulu during the 2025-26 water year, significantly exceeding its annual share of 176.85 tmcft.

During the previous DMK government (2021-26), the Mettur Dam was opened on the scheduled date in three out of five years, while in 2022 it was opened ahead of schedule.

In 2023, however, irrigation releases began only on July 29 when storage had reached nearly 88 tmcft. Officials estimate that with the current storage, water availability may support kuruvai cultivation across only about 2.5 lakh acres, aided by nearly  one lakh borewells and filter points.

In recent years, normal kuruvai coverage has been around 4.4 lakh acres, while last year it touched a record 6.09 lakh acres. Experts estimate that irrigating even three lakh acres would require at least 80 tmcft of water.

The state government is reportedly considering a special assistance package for farmers and is also exploring measures to encourage cultivation of pulses as an alternative crop.

Agricultural experts have advised farmers to complete pulse sowing, particularly black gram, by the second week of June to avoid potential damage from heavy rain during the latter phase of the southwest monsoon or the onset of the northeast monsoon later in the year.