In a significant development for water resources in South India, Tamil Nadu has received a substantial surplus of water from the Cauvery river by the close of December 2025. The state benefited from an excess inflow of 140.03 thousand million cubic (tmc) feet of water, a direct result of bountiful rainfall during the key monsoon periods.
Monsoon Bounty Drives Inflows
The surplus was made possible by excellent rainfall activity during both the Southwest Monsoon (SWM) and the Northeast Monsoon (NEM). The cumulative effect of rains from June 1 to December 31, 2025, significantly replenished the reservoirs across the Cauvery river basin. Hydrological data indicates that the dams in the catchment area received a total inflow of 414 tmc ft of water during this seven-month period.
Water Release and Distribution
Following standard operating procedures and interstate water-sharing agreements, the authorities managed the substantial inflows by releasing water downstream. The total quantum of Cauvery water released from the dams was recorded at 389 tmc ft. This managed release ensured that the excess water, calculated at 140.03 tmc ft, successfully reached Tamil Nadu, aiding in irrigation, drinking water supply, and groundwater recharge in the state.
Implications for the Region
This surplus arrival of water is a positive development for Tamil Nadu, especially for its agricultural sector in the Cauvery delta region. Good storage levels in reservoirs provide a buffer and improve water security for the upcoming summer months. The data, reported on January 10, 2026, highlights how favorable monsoon conditions can directly impact water resource management and interstate water sharing dynamics in the basin.
The robust rainfall pattern during both monsoon seasons of 2025 proved to be a critical factor, transforming the water availability scenario in the region. Such periods of abundance are crucial for maintaining the balance in the often-disputed Cauvery river system, benefiting all stakeholders dependent on its waters.
