A group of protestors are setting off from the Indian capital, Delhi, for the site of the Narmada Dam. The Indian government has spent millions of dollars on the project, which, it says, will be a boon for India's three western states.

Listen to Sanjeev Srivastava's report from Jalsindhi

But protestors say the dam has come at a huge environmental and human cost.

They say nearly 250 villages will be swallowed up by the waters of the Narmada river and nearly a quarter of a million people will be displaced.

Many local people are threatening to stay in their villages and drown as the waters rise, rather than leave their homeland.

Displaced villagers

The remote western Indian village of Jalsindhi lies in the dam's basin and would be among the first villages in the western Indian state of Gujarat to be submerged, if water levels in the river rise this monsoon.

Farmland will be submerged once the dam is complete

The government has offered alternative land to the families living in the village. But the plots are 150 km away. And, as one of the village women, Perwi Devi, explained, the offer is not good enough to induce them to leave their ancestral homes.

"What else can we do? The government doesn't offer us proper land. It offers us land which has already been farmed by other people, which has some kind of quarrel attached with it," Perwi Devi told the BBC.

"The world is so big - why can't the government find forest land and give it to us?" she said.

But the government appears to be in no mood to give in to the villagers' demands. In fact, construction work on the dam is continuing apace.

It is already a massive 80 metre structure, stretching across the Narmada River. But the government recently won a three-year legal battle which has allowed them to add an extra eight metres to its height

Development needs

The result, say opponents, will be that more villages will be lost underwater for ever, as the river water rises. The government says its provision for the people of these villages has been generous.

Nearly 250 villages will be swallowed by the waters

"In India, for example, we have the monsoon only for four or five months of the whole year. We need to store water," said Vinod Babbar, the official in charge of resettling the tribal people of the area.

"In the past, we stored water in small projects. They dry up after the first consecutive drought. And we've been having three years of consecutive droughts.

"In foreign countries, they have built a large number of dams already, in the 1930s to 1950s. And they have utilised about 90-95% of the river waters. In Narmada, the utilisation of the water is only 10%," he said.

The government argues that this is a vital development that will irrigate huge areas of land, generate power and provide drinking water. India needs this dam, they say.

But many are not convinced, saying that the environmental and human costs will be too high.

Forceful protest

In the 15 years since construction work started, a strong anti-dam campaign has developed.

Parveen Jahangir is a member of the Save Narmada Campaign.

An anti-dam protest by the banks of the Narmada

"Now, what basically we want is a true development, where people don't have to be displaced for imaginary benefits," she told the BBC.

"And the facts of the case must be made public. The people affected by these projects should be part of the decision-making process. What we are looking for is true development and an equitable development," she said.

Anti-dam feeling is at a high. But it is unlikely the government will bow to pressure. Since the World Bank withdrew funding from the project, after opposition from environmentalists, the government has had to pay all the bills.

The dam has already cost nearly $2bn - money that some would say has been well-spent.

Venkat Rao, news editor of the Bombay edition of The Indian Express, has watched the dam being built and believes that it does offer many benefits.

"Keeping that in mind, and the fact that we are a democracy, it is for us to balance the equation: the larger good for the larger number of people," Mr Rao said.

The Narmada River has sustained life in parts of western India for centuries.