Tamil Nadu Faces Low Reservoir Storage and Potential Water Shortage

Tamil Nadu faces a possible water shortage and lower rice production unless the Northeast monsoon brings heavy rain soon. The aggregate storage in the major 15 irrigation reservoirs is currently about a third of their combined capacity, compared to around 92% at the same time last year. The State's largest dam, Mettur, holds about 23 thousand million cubic feet, which is barely enough to maintain water release to farmers in the Cauvery delta for more than a week. The State has received around 240 mm of rainfall so far against the anticipated 236 mm, but it needs at least 260 mm more to be comfortable, mostly during November.

Cultivation Status

Farmers have raised paddy for the samba-thaladi season on about 3.62 lakh hectares in the Cauvery delta. Nearly 50% of this area uses the direct sown method where seeds are put straight into the soil instead of transplantation, which is common during water shortages. In non-delta areas, paddy coverage is about 1.3 lakh hectares shorter than last year, and the share of direct sowing has risen from 39% previously to about 57% this time. Rice production in 2025-26 reached 77.5 lakh tonnes, which was lower than the peak of 79.07 lakh tonnes in 2021-22.

Official Demands

To protect crops in the Cauvery delta, the State government demanded at meetings of the Cauvery Water Regulation Committee and the Cauvery Water Management Authority that Karnataka release around 20.7 tmcft, including a backlog of about 16.9 tmcft. However, the Authority ratified the Committee's recommendation for Karnataka to release 3.88 tmcft at 3,000 cusecs per day for 15 days starting November 7, 2026.

Context

Monsoon rainfall patterns in Tamil Nadu dictate agricultural cycles and drinking water availability across both delta and non-delta regions. Irrigation reliance on major reservoirs like Mettur highlights how inter-state water sharing and seasonal rains directly shape state food production.