The Bhakra dam on the Sutlej was begun in 1948 and completed in 1963. It is 226 metres high, a straight concrete gravity dam in a gorge in the Shivaliks, and it was the largest project of its kind in India when built.
Nehru called dams the temples of modern India, and said it at Bhakra. Its power and its water made the Green Revolution in Punjab possible: the Bhakra canal system irrigates a large part of the Malwa and the state's electricity supply depended on it for decades.
Around 36,000 people were displaced by the reservoir, Gobind Sagar, most of them from Bilaspur in what is now Himachal Pradesh. Compensation and resettlement were incomplete and remained a grievance for generations.
The dam was designed under the American engineer Harvey Slocum. Fourteen hundred workers are recorded as having died in its construction.
It is the piece of infrastructure that changed Punjab most in the twentieth century, and it is also the reason the state's water politics, its power subsidies and its groundwater crisis all take the shape they do.
The dam is over two hundred metres high and it was the largest project of independent India's first decade, described by Nehru as a temple of the new age.
The reservoir displaced the population of the Bilaspur valley, including the town, and the resettlement of those families is still a live grievance.
It waters Punjab, Haryana and Rajasthan and generates power for all three. The whole argument about the rivers between those states is an argument about the water this dam holds.