Punjab's water is held in four large reservoirs, none of which is in Punjab.
Gobind Sagar behind Bhakra on the Sutlej is in Himachal Pradesh. Pong on the Beas is in Himachal. Ranjit Sagar on the Ravi is on the Punjab and Jammu boundary. Nangal below Bhakra is the regulating pond.
Together they store the water that Punjab's canals distribute and generate a large part of the power the state uses.
They are managed by the Bhakra Beas Management Board, a body answering to the central government with Punjab, Haryana, Rajasthan and Himachal as beneficiaries, and its composition and control have been disputed by Punjab repeatedly.
The reservoirs displaced tens of thousands of people, principally in Himachal, and the resettlement was incomplete.
Punjab's agriculture depends on structures located outside the state, operated by a board it does not control, filled by rainfall in a third state. The politics of Punjab's water follows from that geography and not only from its grievances.
Ranjit Sagar is the newest and the most argued over. Begun in 1981 and finished in 2001, it needed the Shahpurkandi barrage below it before the released water could be used, and that barrage was stopped for two decades in a dispute with Jammu and Kashmir, during which the water ran on across the border.
Gobind Sagar drowned Bilaspur town, which is under the water and visible in a low year. Pong drowned something like two hundred and fifty villages in the Kangra valley. Oustees of both were promised land in Rajasthan, some of them got it, and the claims of the rest have been running for half a century.
The reservoirs are silting. Live storage falls each decade and there is no way to remove silt at that scale, so the system's buffer shrinks while demand grows.