Hirakud Dam, built on the Mahanadi River in Odisha, is the longest dam in India with a total length of 25.8 km, including the dam and dykes, and a main dam length of 4.8 km. Located about 15 km upstream of Sambalpur town, it was India’s first major multipurpose river valley project after independence. The dam is a composite structure made of earth, concrete, and masonry. It plays a key role in flood control, irrigation, and hydroelectric power generation.

The dam irrigates approximately 4.36 lakh hectares in the Mahanadi delta and has an installed power generation capacity of 307.5 MW. Hirakud intercepts a vast catchment area of 83,400 sq. km and forms a reservoir spread over 743 sq. km at full reservoir level. The reservoir has a live storage capacity of 5,818 million cubic meters and a gross capacity of 8,136 million cubic meters. Hirakud Dam remains a landmark in India’s infrastructure development.