The company said that it had put two-thirds of the installed capacity back in operation as the silt loading reduced to approximately 4500ppm.
SJVN shut down the entire plant on 11 June when glacial meltwater brought a surge in silt load in excess of the 4000ppm permissible limit in the river. Local media reported that the silt content in the river Satluj was in excess of 9500ppm.
With two units - or 500MW of installed capacity still out of action - the company said that it plans to put them back into operation as the silt load recedes further. The project operates with a 3500ppm limit for water at the intake, which corresponds to silt loading in the river of 4000ppm.
Nathpa Jhakri entered full commercial production in May 2004 and has seen a mostly upward trend in electricity output. The company recently received an insurance payout over losses caused by major river flooding at Nathpa Jhakri in September 2005.
The project infrastructure has major desilting chamber arrangements due to the silt problem in the region. Following the floods of 2005, studies are looking at various measures to further improve desilting, such as reservoir operations, dredging, upstream storage dams, catchment treatment to reduce bank erosion, and building a new diversion tunnel.
