India has said the Indus Water Treaty (IWT) of 1960 with Pakistan will be held in abeyance with immediate effect, until Islamabad credibly and irrevocably abjures its support for cross-border terrorism.
The move on Wednesday after the killing of 26 persons, including tourists, in Pahalgam in Jammu and Kashmir on Tuesday.
What could be the impact of this move?
The Indus system of rivers comprises the main river -- the Indus -- along with its five left bank tributaries, namely, the Ravi, the Beas, the Sutlej, the Jhelum and the Chenab. The right bank tributary, the Kabul, does not flow through India.
The Ravi, the Beas and the Sutlej are together called eastern rivers while the Chenab, the Jhelum and the Indus main are called as western rivers. Its waters are critical to both India and Pakistan.
Pradeep Kumar Saxena, who served as India's Indus Water Commissioner for over six years and has been associated with work related to the IWT, said India, as an upper riparian country, has multiple options.
"This could be the first step towards the abrogation of the treaty, if the government so decides," Saxena told PTI on Wednesday.
"Although there is no explicit provision in the treaty for its abrogation, Article 62 of the Vienna Convention on Law of the Treaties provides sufficient room under which the treaty can be repudiated in view of the fundamental change of circumstances which has occurred with regard to those existing at the time of conclusion of the treaty," he said.
Last year, India sent a formal notice to Pakistan, seeking the "review and modification" of the treaty.
Listing out the steps India could take, Saxena said in the absence of the treaty, India is under no obligation to follow the restrictions on the "reservoir flushing" of the Kishanganga reservoir and other projects on western rivers in Jammu and Kashmir. The Indus Water Treaty currently prohibits it.
Flushing can help India desilt its reservoir but then filling the entire reservoir could take days. Under the treaty, reservoir filling after the flushing has to be done in August -- peak monsoon period -- but with the pact in abeyance, it could be done anytime.
Doing it when sowing season begins in Pakistan could be detrimental, especially when a large part of Punjab in Pakistan depends on the Indus and its tributaries for irrigation.
According to the treaty, there are design restrictions on building structures like dams on Indus and its tributaries. In the past, Pakistan has raised objections over the designs but in future it will not be obligatory to take the concerns onboard.
In the past almost every project has been objected to by Pakistan.
Notable are Salal, Baglihar, Uri, Chutak, Nimoo Bazgo, Kishenganga, Pakal Dul, Miyar, Lower Kalnai and Ratle.
After the Pulwama terror attack in 2019, the government cleared eight more hydropower projects in Ladakh.
The objections may no longer be applicable for the new projects.
There are also operational restrictions on how reservoirs are to be filled and operated. With the treaty in abeyance, these are no longer applicable.
Saxena said India can stop sharing flood data on the rivers. This could also prove detrimental to Pakistan, especially during the monsoon when rivers swell.
India will now have no restriction on storage on western rivers, particularly the Jhelum, and the country can take a number of flood control measures to mitigate floods in the Valley, he said.
The tours of Pakistan side to India, which are mandatory under the treaty, may now be stopped.
At the time of Independence, the boundary line between the two newly created independent countries --- Pakistan and India --- was drawn right across the Indus Basin, leaving Pakistan as the lower riparian and India as the upper riparian.
Two important irrigation works, one at Madhopur on the Ravi river and the other at Ferozepur on the Sutlej river, on which the irrigation canal supplies in Punjab (Pakistan) had been completely dependent, fell in the Indian territory.
A dispute thus arose between the two countries regarding the utilisation of irrigation water from existing facilities. Negotiations held under the International Bank for Reconstruction and Development (World Bank) culminated in the signing of the Indus Water Treaty in 1960.
According to the treaty, all the waters of the eastern rivers - Sutlej, Beas, and Ravi with an average annual flow of around 33 million acre feet (MAF) is allocated to India for unrestricted use while the waters of western rivers - Indus, Jhelum, and Chenab with average annual flow of around 135 MAF is allocated largely to Pakistan.
However, India is permitted to use the waters of the western rivers for domestic use, non-consumptive use, agricultural and generation of hydro-electric power. The right to generate hydroelectricity from western rivers is unrestricted subject to conditions for the design and operation of the treaty. India can also create storages up to 3.6 MAF on western rivers, the pact states.
