NEW DELHI: Water levels in India's main reservoirs were at 57 per cent of capacity in the week to Aug 23, down 12 percentage points from a year ago, reflecting this year's weak monsoon, government data showed on Friday.

The latest level was equal to the 10-year average for the week. It was six percentage points higher than the previous week, reflecting improvement in the monsoon since the last week of July.

Reservoirs are primarily important for hydropower, which accounts for a quarter of India's generation capacity, but they are also used during the summer for irrigation if monsoon rains are not enough for planting crops such as cotton.

The reservoirs provide water later in the year to irrigate winter crops such as wheat and rapeseed.