HANSI, INDIA -- A failure of the annual monsoon rains to arrive this year is threatening this nation of 800 million people with a drought unmatched in decades.

Fields all across the country that normally are lush and green with the annual rice crop lie barren and parched. Buffalo and cattle, starved for green fodder, give half their normal supply of milk. The groundnut crop, a primary source for the oils central to Indian cuisine, is almost a total loss.

The scope of the impending crisis became clear last week when Agriculture Secretary G.S. Dillon told the parliament that 25 of the nation's 35 meteorological zones have received deficient rainfall this year, with many of them 50 percent or more below normal.

If the monsoon does not revive itself as the season wanes, experts are warning that not only will current crops be a disaster but that future plantings will also be affected, since reservoirs will remain dry and groundwater -- already declining at an alarming rate -- will be depleted even further. Normally, the rainy season closes at the end of September.

In the cities and the countryside, a frantic search for water, both for irrigation and drinking, has begun.

In Madras, where two of the city's three reservoirs are bone dry, authorities and entrepreneurs are importing limited supplies. Hyderabad brings its supplies in by railway tank cars. In New Delhi, the already limited availability has been cut even further due to limited supplies and power outages that stop the water authority's pumps.

Even before this year's drought the situation was critical. International experts put the minimum water supply to maintain proper health at 80 gallons per person per day. None of India's cities or towns comes even close. Delhi, at 50 gallons per day before the drought, was at the top of the list.

It is in the countryside, however, that the impact of sparse rainfall is most dramatic.

Prem Singh stood in the bed of a huge canal near here last week. Normally full of life-giving water, the canal is now virtually dry with only a few remaining pools to which local farmers bring their buffalo and cattle.

"There has been no rain this year, nothing," the 32-year-old farmer said. "We haven't seen anything like this for 80 years. Our parents are telling us, 'We have seen nothing like this.' Even the old men tell us."

Haryana and the neighboring states of Punjab and the western part of Uttar Pradesh are among the main breadbaskets of modern India, beneficiaries of more than two decades of irrigation projects, farm mechanization and the "green revolution" of new seeds and fertilizers.

It is because of their abundance, and slower but corresponding progress elsewhere in this vast land where three-fourths of the people live in villages, that so far experts are talking only of devastating drought and not famine.

With 23 million tons of grain reserves and a reasonably well developed transportation system, India has the capacity to avert mass starvation at least for this year, if its unwieldy bureaucracy carries out the pronouncements of the politicians in New Delhi. Still, it is a dramatic turnaround from just a few months ago, when India could boast of being a net food exporter.

Managing the current drought will be a critical test for Prime Minister Rajiv Gandhi and his Congress (I) party. Already hard pressed politically by allegations of corruption and political failures, Gandhi can ill afford to head a government that fails to meet the challenge of a drought that is likely to affect 80 percent of the nation's villages, towns and cities. Gandhi has named himself to head a national drought crisis committee.

Areas like those around Hansi represent a best-case situation for Gandhi and his planners.

Balwant Singh, 52, owner of about 10 acres, says that with irrigation there are some crops. "We have some sugar cane and sorghum for the animals but only on about half the land," the tall, lean farmer said as he watered his cattle in the small pool of a drying canal bed. "The other half is empty. There is no water, no rain. All the farmers are in trouble for water."

A few miles up the road, Daram Beer looked out over fields that normally would be full of cotton, his major cash crop. This year, most are barren or full of stubble from cotton that could not get water at the critical time. Crops that grow a fraction of their usual height reflect this same loss.

Beer's land is close to a major canal but he says water is available only sporadically. "We get water for one acre for maybe 20 minutes a week, but we need eight hours an acre," he said.

Even in areas where there is water available from tube wells, farmers have been reluctant to plant all their fields. Bhagat Ram, an apparently wealthy landowner near Mehan, has a new pump house but his wife says the diesel fuel to run the pump costs too much to irrigate all their fields. "We are waiting for God for the rain," she says.

While they wait, the impact of the sparse rainfall is acutely felt.

Dr. R. M. Bhardwarj, a veterinary expert at the Haryana Agricultural University in Hisar, says buffalo that normally give 22 to 33 pounds of milk per day now are giving half that amount and signs of serious animal diseases are beginning to show. As a result, milk prices already have risen 20 percent.

"The animals are not getting any green fodder. They feed only on dry fodder and they are unable to digest their food. The milk yield is down drastically and stomach diseases are developing," he said. The result, he said, will cause people to move, or sell their livestock.

"If a farmer buys a buffalo for 6,000 rupees {about $400} but has no food, he will have to sell it at distress prices, probably about 2,000 rupees. He loses money, he loses milk, he loses the other by-products. Then he goes into debt and once he is in debt, it is perpetual debt. It is a major problem in drought areas."

Nationally, agriculture officials say 31 percent of the rice crop is in trouble, 50 percent of the coarse grains, 33 percent of the lentils and 65 percent of the groundnuts. If there is no rain in critical areas in the next few days, these statistics are expected to worsen.

In an effort to save as much of the crop as possible, officials have ordered a shift in available electrical supplies to power irrigation pumps wherever water is available. The result is that factories in major agricultural areas are being deprived of electricity, already limited due to water shortages for hydropower.

Even in the best of times, scores of millions of rural Indians eke out a subsistence living doing seasonal agricultural labor. With crops withering under rainless skies, there will be no work available, and no work means no food, even if some produce makes it to the market.

Special correspondent Nilova Roy in New Delhi contributed to this report.