The foundation of the reservoir spread in an area of 627 sq km was laid by Babu Jagjivan Ram on June 4, 1976, an official statement said here.
Manjhi said that many challenges came in during nearly four decades in completion of the project.
"Due to firm commitment of former chief minister Nitish Kumar, the project has seen the light of the day," he said.
He said the reservoir could irrigate 39,620 hectares of land in different areas of Kaimur and Rohtas districts.
Water Resources Minister Vijay Chaudhary also gave credit to Nitish Kumar for completion of the project.
He said the work of irrigation process in the project would be completed soon.
