Tamil Nadu Records 50-Year Low in July Cauvery Water Realisation

August 3, 2026

Tamil Nadu experienced its lowest July realisation of Cauvery water in 50 years, receiving less than one thousand million cubic feet (tmcft) for the entire month. According to data cited in an application filed by the Tamil Nadu government before the Supreme Court, the state received only 0.698 tmcft of water at Biligundulu in July, falling far short of the stipulated share of 31.24 tmcft.

What Happened

Data regarding water flow indicates a sharp decline in Tamil Nadu’s share of Cauvery water during the current season. By August 2, total realisation at the Biligundulu measuring station reached 3.687 tmcft, comprising 2.915 tmcft in June, 0.698 tmcft in July, and 0.074 tmcft in early August. Under the tribunal award modified by the Supreme Court, Tamil Nadu’s prescribed allocation for the first two months combined stands at 40.43 tmcft.

Historical records identify July as the worst-performing month for water allocation to Tamil Nadu over the past five decades. Prior to this, the lowest July flow recorded at Biligundulu was 2.441 tmcft in 2003. When Mettur dam served as the reference point before 2012, the lowest July inflow was also recorded in 2003 at 1.5 tmcft. Other previous years with significantly reduced July realisations include 1987 (3.392 tmcft at Biligundulu and 2.286 tmcft at Mettur) and 2012 (4.153 tmcft at Biligundulu and 1.033 tmcft at Mettur).

Key Highlights

July water realisation at Biligundulu dropped to 0.698 tmcft against the mandated target of 31.24 tmcft.
Cumulative realisation from June through August 2 stood at 3.687 tmcft, compared to the required two-month allocation of 40.43 tmcft.
The current July figure represents the lowest monthly allocation for Tamil Nadu in 50 years.
Past low-realisation years for July include 2003 (2.441 tmcft at Biligundulu), 1987 (3.392 tmcft), and 2012 (4.153 tmcft).
A 2016 Supreme Court-appointed study highlights average July realisations at Biligundulu of 36.871 tmcft over 25 years and 39.087 tmcft over 42 years.

Why This Matters

The historical baseline compiled by a High Level Technical Team in 2016 illustrates the magnitude of the present shortfall. The team’s analysis revealed a 25-year average July realisation of 36.871 tmcft at Biligundulu and a 42-year average of 39.087 tmcft. Corresponding historical averages for Mettur were 33.7 tmcft over 25 years and 36.2 tmcft over 42 years. The study benchmarked 25 years from the 1991 tribunal interim order and 42 years from the review period of clauses in the 1924 Cauvery Accord signed between the Madras Presidency and the princely State of Mysore.

What to Watch Next

The Tamil Nadu government has approached the Supreme Court regarding the shortfall in water realisations. Further legal proceedings and directions from the Supreme Court will determine the next steps in this matter.

Frequently Asked Questions

What is the official measuring location for Cauvery water flow to Tamil Nadu?

Since the enforcement of the Cauvery Water Disputes Tribunal’s final award in 2013, Biligundulu has served as the official measuring site for water inflow into Tamil Nadu. Mettur dam was used as the reference point up to 2012.

How much Cauvery water was Tamil Nadu supposed to receive in July?

According to stipulated allocations, Tamil Nadu was required to receive 31.24 tmcft of Cauvery water in July, but realised 0.698 tmcft.

What is the total allocation required for June and July combined?

Under the tribunal award as amended by the Supreme Court, Tamil Nadu is required to receive 40.43 tmcft across the first two months of the season.

Source: Based on Tamil Nadu state court filings and reporting by The Hindu.