Key Facts

Tamil Nadu's normal northeast monsoon rainfall is about 434 mm, most of it received in October and November, with December usually contributing only about 20%. Storage in the state's 15 major reservoirs stood at about 35% of capacity in early November, against 88% a year earlier, with Mettur (the Stanley Reservoir) on the Cauvery in Salem district, the state's largest dam, holding about 24.7 tmcft. The state received about 248 mm of rain from 1 October to 8 November against an expected 236 mm, but needs at least 260 mm more to reach normal levels. The Cauvery Water Management Authority ratified a release of 3.88 tmcft from Karnataka at 3,000 cusecs a day for 15 days from 7 November.

GK Context

The Cauvery Water Management Authority (CWMA) was constituted in 2018 following a Supreme Court order to implement the tribunal award on sharing Cauvery waters among Tamil Nadu, Karnataka, Kerala and Puducherry. Mettur Dam, built in 1934 across the Cauvery, feeds the delta irrigation system through the Grand Anicut (Kallanai), one of the world's oldest water-regulation structures, built by the Chola king Karikalan. A 'tmcft' (thousand million cubic feet) is a standard unit for measuring large reservoir storage and river flows in India.