History of the dispute

1924: The British brokered an agreement, which was to be operative for 50 years. TN and Puducherry would get 75% of the surplus water while Karnataka would get 23%. The remaining would go to Kerala. There were also restrictions on how much land could be irrigated

1970: The Cauvery Fact Finding Committee found that Tamil Nadu’s irrigated lands had grown from 1,440,000 acres to 2,580,000 acres while Karnataka’s irrigated area stood at 680,000 acres, resulting in an increased need of water for TN. Karnataka opposed this proposal

2007: The Cauvery Water Disputes Tribunal holds the two British era agreements valid but all states filed clarificatory petitions in the SC

2013: TN files contempt petition in the SC against Karnataka. CM Siddaramaiah refuses to implement the decision to release additional water

Sept 2016: SC directs Karnataka to release 15,000 cusecs a day till Sept 15. Protests break out in Karnataka, which releases water and files a plea to the SC order

July 14, 2017: Karnataka seeks a reduction in the quantum of water it should release to TN

Sept 20, 2017: The Supreme Court reserved its judgment

Feb 16, 2018: The SC reduces Tamil Nadu’s share of Cauvery river water to 177.25 thousand million cubic feet (tmcft), down from 192 tmcft allocated by a tribunal in 2007.