New Delhi: Water in India’s main reservoirs rose to 42% of capacity on 27 August, government data showed, and the slower-than-normal rise of 3 percentage points increases the risk a poor monsoon will hit the winter crop.

The rise, smaller than a 10-year average of a rise of 5 percentage points for the week, indicates the net impact of last week’s monsoon rainfall was worse than the 5% deficit shown in the weather office data.

“Water storage in reservoirs is a very good regionalised and robust indicator of realistic rainfall in the vast catchment. It is a much better and practical parameter as compared to point estimate measured by rain-gauges,” the farm ministry said in recent note.

Reservoirs are important for hydropower, which accounts for a quarter of India’s generation capacity of about 150,000 megawatts. They also provide water to irrigate winter crops.

The water level was one-third lower than last year’s 63% and one-quarter below the 10-year average of 57%, the data showed.

Reservoirs in northern India were at 22.9% of capacity in the Ganga basin, well below the 10-year average of 37%, while those in the Indus basin had filled up to 36 percent of capacity, sharply lower than the usual 67.9%.