The main dispute between Karnataka and Tamil Nadu is related to the sharing of river water.

Background:
The conflict over the sharing of Cauvery river water dates back to the British era when the Madras Presidency (present-day Tamil Nadu) and the princely state of Mysore (present-day Karnataka) were under British rule. The British had established an agreement in 1892 and 1924 to share the water of the Cauvery river between the two states. However, the issue resurfaced after India gained independence in 1947 and the states were reorganized on linguistic lines.

Reasons for the dispute:
The dispute arises because the Cauvery river flows through Karnataka before reaching Tamil Nadu. Karnataka claims that it needs the water for irrigation and drinking purposes, especially during the dry season. On the other hand, Tamil Nadu claims that it is entitled to a certain amount of water according to the agreement signed in 1924. The state argues that the livelihoods of farmers and the overall economy of the state depend on the water from the Cauvery river.

Attempts to resolve the dispute:
The Cauvery Water Disputes Tribunal (CWDT) was set up in 1990 to resolve the issue. The tribunal gave its final verdict in 2007, which allocated the water between the two states. However, both states have been unhappy with the verdict, and the issue is still unresolved. There have been protests, strikes, and even violence between the two states over the years, with both sides accusing each other of not adhering to the agreement.

Conclusion:
The dispute over Cauvery river water has been a long-standing issue between Karnataka and Tamil Nadu. Despite attempts to resolve the issue, the two states have not been able to reach a satisfactory agreement. The issue highlights the importance of water management and the need for effective dispute resolution mechanisms.