NEW DELHI—India's paralyzing power outages this week have focused attention on this year's weak monsoon season, as below-normal water levels in some hydroelectric dams mean both less electricity to go around and farmers pumping more water instead of depending on rain.

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The combination of lower supply and higher demand is adding stress to a system that already has proved very rickety and that earlier this week suffered two massive hourslong outages. Tuesday's blackout was the largest yet, spanning an area of northern and eastern India inhabited by 680 million people.

The specific cause of those outages is still being investigated. Some initial reports have blamed the collapse on rain-deficient states overdrawing their power allotments from the grid, while others say the fault was technical and due to shabby infrastructure.

A farmer walks through parched paddy ﬁelds on the outskirts of Jammu, India. Associated Press

Either way, analysts say the effect of insufficient monsoon rains is likely to mean that widespread outages—though not necessarily on such a colossal scale—become more frequent in coming weeks and months, especially in breadbasket states.

More than halfway through the season, the monsoons are 19% below the long-term average. In the worst-affected states in northern India, which are heavily agricultural, farmers are relying more than usual on electric pumps to draw groundwater.

Electricity demand also is higher because the rains usually cool the searing summer heat of May and June. With little rain, the demand from air conditioners and cooling systems has stayed high.

"The weak monsoon has increased the load by 20% of our normal," said C.S. Chandalia, director of Power Trading Rajasthan Discom, the state electric utility in the northwestern state of Rajasthan.

He said the company is cutting electricity for an hour and a half in the morning and for the same duration in the evening to conserve supplies.

In Punjab, another heavily agricultural state, "we are diverting power from industries to agriculture," said Anuradh Tewari, the state's power secretary. The state is crucial to India's food security, he said, and agriculture must take top priority.

He added: "August is a crucial month. If rain doesn't come, things are going to get really serious. We will be left with no option but to manage the widening electricity demand and supply gap through power cuts."

Already, power cuts are commonplace. A month ago, industries in the state were grappling with a power supply that lasted only five to six hours a day, an official at a fertilizer company said. Today, that has been reduced to three to four hours.

As a measure of how little rain has fallen, water levels in 84 important reservoirs nationwide are about 55% of last year's storage levels and 76% of the 10-year average. In Punjab, the storage of water is 63% of the 10-year average as of July 26, according to government data.

The shortage in the reservoirs also can force more pump usage in fields because the reservoirs supply irrigation canals from which farmers draw water. If the canals don't meet farmers' needs, they resort to pumping from underground.

One farmer in Punjab estimated that water pumping was so widespread that levels in tube wells have fallen by three to four feet in the last month alone.

India has struggled for years to increase the capacity of its power sector to meet the regular needs of its population, let alone surprise surges in demand. Most of the system runs on coal, which is in short supply, limiting generators' ability to increase production. And almost 20% comes from hydroelectric plants that rely on snow melt from the Himalayas—and monsoon rains.

The Bhakra Nangal Dam in Punjab is the second-largest in India. Through two reservoirs, it supplies water to two other states. Starting July 5, authorities decided to reduce water supply from the reservoirs by 10% in order to conserve water for coming months, said S.L. Aggarwal, an official at the dam.

That, in turn, has reduced the power supply from the dam's two hydroelectric turbines. Anirudh Tewari, secretary in the power ministry in Punjab, said hydroelectric generating capacity at the dam and other hydro projects in the state was down about 12% from the same time a year ago.

Representatives from the states of Punjab, Haryana and Rajasthan will meet Tuesday to assess the water situation and decide on further steps.

All three states were hit by the giant power outages Monday and Tuesday. On Monday, the northern distribution collapsed; on Tuesday, the northern grid collapsed again, and the eastern and northeastern grids did, too.

—Debiprasad Nayak in Mumbai contributed to this article.

Write to Biman Mukherji at, Saurabh Chaturvedi at and Santanu Choudhury at