Tamil Nadu's 90 monitored reservoirs held just 83.124 thousand million cubic feet (tmcft) as of Monday, 18 August — a mere 37.05 per cent of their combined capacity of 224.343 tmcft, according to the state's Water Resources Department. An underperforming southwest monsoon and unusually high temperatures have pushed the state's water crisis to its most severe point in at least a year, raising urgent concerns over irrigation and drinking-water availability across several districts.

How Bad the Storage Deficit Is

The current storage level is less than half of what it was during the same period last year, when the same reservoirs collectively held 189.545 tmcft. Of the 90 reservoirs, 58 have less than 25 per cent storage, 14 are between 26 and 50 per cent, 15 are between 51 and 76 per cent, and only two have crossed the 80 per cent mark. The sole exception is the Gundar reservoir in Tenkasi district, which has reached its full capacity of 18.43 million cubic feet.

Mettur's Critical Shortfall

Mettur Dam, Tamil Nadu's most strategically important reservoir for Cauvery delta irrigation, held 43.275 tmcft on Monday — just 46.30 per cent of its total capacity of 93.470 tmcft. A year ago, it stood at 91.114 tmcft, or 97.48 per cent of capacity. While water availability along the Cauvery between Mettur and Tiruchy remains relatively stable, downstream and tail-end areas are experiencing serious shortages, including difficulties in meeting basic drinking-water requirements. Officials have said maintaining a stable supply-demand balance is becoming increasingly difficult in reservoir-dependent regions. Storage in other major irrigation reservoirs — Bhavanisagar, Amaravathi, and Vaigai — also remains poor.

Karnataka's Cauvery Releases Fall Short

The situation is compounded by Karnataka's failure to release Tamil Nadu's stipulated Cauvery share, according to Water Resources Department officials. Under the Supreme Court's final order, Karnataka was required to release 9.190 tmcft in June and 31.240 tmcft in July. Tamil Nadu, however, received only 2.915 tmcft in June and 0.7138 tmcft in July — a fraction of the mandated volumes. This comes despite comparatively healthy storage in Karnataka's four major Cauvery-linked reservoirs: Krishnaraja Sagar at 63.64 per cent, Kabini at 92.31 per cent, Harangi at 97.06 per cent, and Hemavathy at 86.56 per cent.

What Comes Next

Officials now consider it unlikely that Mettur will reach full capacity this season. With the southwest monsoon yielding inadequate rainfall, Tamil Nadu will depend heavily on the northeast monsoon later this year to replenish reservoirs and ease mounting pressure on agriculture and drinking-water supplies. The state's water outlook for the coming months will hinge critically on how the northeast monsoon performs — and whether Karnataka releases the Cauvery water owed under court order.