The state electricity board started work on the Ghanvi river a tributary of the Sutlej in 2004 and the proposed cost was Rs 49 crore.
It was to be completed in March 2007 but has taken almost eight more years shooting up the construction cost three and half times to Rs 173 crore.
While the project has been built by the state electricity board .The dam and intake reservoir by Hydro Construction Power Company.
Inaugurating the project state chief minister Virbhadra Singh said the project will generate 56 million units of power annually bringing a revenue of Rs 12 crore.
Officials said electricity produced will be routed through the northern grid.
The Himachal electricity board is known for its inefficiency it is also the most over-staffed power board in the country.
Since long in the red it has accumulated losses of some Rs 1300 crore.