New Delhi, June 12 -- Hydropower, the silent anchor of India's electrical grid, may face a severe supply threat this fiscal year, as a weak monsoon fails to top up depleted reservoirs. The likely shortfall comes at a precarious time for the country, where power demand has already shattered records and is projected to climb even higher in the coming months.

The India Meteorological Department (IMD) expects El Niño to cast shadow over this year's monsoon, and has accordingly revised its rainfall forecast to 90% of the 50-year average. El Niño had taken a toll of 12% on hydropower generation in 2015-16.

Given the threat of a weak monsoon and the state of reservoirs, this year's hydropower generation may be around 10% lower than l...