The multi-purpose Hirakud Dam across the river Mahanadi was constructed for flood control, irrigation and power generation. Hirakud Dam is a composite structure of earth, concrete and masonary. The Main dam having an overall length of 4.8 km spans between hills Laxmidungri on left and Chandli-dungri on the right. The dam is flanged by 21 km long earthen dykes, both on left and right sides to close the low saddles beyond the abutment hills. It has the distinction of being at one time the longest earth dam in the world, being 25.8 km long with dams and dykes taken together. It also has the rare distinction of forming the biggest artificial lake in Asia with reservoir spread of 743 sq. km at full reservoir level. Hirakud dam intercepts 83400 sq. km of Mahanadi catchment. The reservoir has live storage of 4-36 million Acer feet with gross storage of 5-83 million Acre feet.
Water from dam enters the turbine through trash rack, intake structure and penstock and gets discharged to the tailrace through draft tube. To control the flow, hydraulic intake gates are provided for each machine. The power component of HPS consists of Power House | at Burla and Power House and Power House - II at Chiplima
The main features of Stage I are dam and appurtenant works, canal system and power generation & transmission. Initially Four generating units with installed capacity 123 MW (2x37.5 + 2x24) were completed in PH-I at Burla.
The main feature of stage II are Power channel, power generation at PH I & II and transmission system. Two more generating units with installed capacity of 75 MW (2 x 37.5) were added in power house Burla. Three generating units with installed capacity of 72 MW (3x 24) were completed in Power House- II at Chiplima. The work under stage II was started on Jan. 1957 and was inaugurated by late Dr. A. N. Khosla.
The work under stage III covers the installation of 7th Unit (37.5 MW) at Power House-I, Burla. The work started on 1st December, 1982 and completed on 13th September, 1990.