Purpose of Construction:-The Hirakud dam is a complex structure and was built for the purpose of irrigation and flood control. It was constructed to regulate the even flow of the Mahanadi River in Orissa. The upper drainage basin of the Mahanadi River, centered on the Chattisgarh Plain. Before the dam was built, the area used to have droughts in the lower basin and violent floods in the upper plain regions. The dam was constructed to put  to an end this situation as it was possible to regulate the flow of water in the desired area  by creating a reservoir and controlling river flow through the drainage system. The dam regulated the flow of  the Mahanadi River and produced hydroelectricity through several hydroelectric plants, thus making judicious use of natural resources as well as technology.

Construction History:-After the devastating floods of Orissa in 1937, legendary engineer Bharat Ratna Sir M. Visveswararya proposed a detailed investigation for storage reservoirs in the Mahanadi basin to tackle the problem of floods in the Mahanadi delta. In 1945, under the chairmanship of Dr. B. R. Ambedkar, the then Member of Labour, it was decided to investigate the potential benefits of controlling the Mahanadi for multipurpose use. The Central Waterways, Irrigation and Navigation Commission took up the work. On 15 March 1946, Sir Howthrone Lewis, the then  Governor of Orissa, laid the foundation stone of the Hirakud Dam. A project report was submitted to the government in June 1947. Pandit Jawaharlal Nehru laid the first batch of concrete on 12 April 1948. The dam was completed in 1953.  Power generation along with agricultural irrigation started in 1956.  The dam was formally inaugurated by Prime Minister  Nehru on 13 January 1957. The total cost of the project at that time was Rs. 100.02 crores. At the time of its construction the project involved submergence of 240 villages with fertile agricultural land of about 40,000 hectares. Around 22,000 families were displaced by the project.  The land-owning  peasants were paid compensation in cash.  

Dam Structure:- The Hirakud Dam is a composite structure of earth, concrete and masonry. It is the longest major earthen dam in the world, measuring 24km including dikes, and stands across the river Mahanadi. The amount of earth, concrete and masonry materials used to build the dam is sufficient to make a road 8 metres wide and pave it from Kanyakumari to Kashmir and from Amritsar to Dibrugarh in Assam. The main dam has an overall length of 4.8 kms spanning between two hills; the Lam Dungri on the left and the Chandili Dunguri on the right. The dam is flanked by 21 km earthen dikes on both the left and right sides, closing the low saddles beyond the adjoining hills. The dam and dikes together measure 25.8 km. It also forms the biggest artificial lake in Asia, with a reservoir holding 743 km² at full capacity, with a shoreline of over 640 km.