The WCD largely vindicates what critics have been saying for years

Patrick McCully, International Rivers Network

The experts, members of the World Commission on Dams (WCD), say decisions on whether to build the structures should respect the interests of everyone concerned.

They say dams account for more than 10% of global food production and almost 20% of electricity generation.

But the people affected by them have little say in their planning and building.

Conflicting interests

The WCD was set up by the World Bank and the World Conservation Union. It is chaired by Professor Kader Asmal, South Africa's Education Minister.

It has tried to find a way through "the increasingly confrontational debate about the role the 45,000 large dams have played in development". Large dams are those over 15 meters high.

Professor Asmal said: "It means nothing to build billion-dollar dams if your monuments alienate the weak.

"It means nothing to stop all dams if your protests only entrench poverty.

Threatened with arrest

"But show me a clear and sustainable way to provide food, energy, stability and running water for those who most need it - that means something. And that we have done."

Arundhati Roy supports protestors

The award-winning novelist Arundhati Roy opposes the building of the Narmada dam in India.

She told BBC News Online: "There are a lot of very important things in the WCD report, though it's obviously a compromise.

"The problem is that it can be used by the funding agencies to pretend they have an enlightened approach, while the reality remains completely different.

"The industry is learning our language and then carrying on just the same.

"And when the WCD members wanted to come to India to see the Narmada site, the Gujarat Government threatened to arrest them."

Inclusive approach

The commission's members surveyed 125 large dams, eight of them in detail. It found that:

• globally, dams account for 19% of electricity generated and for an estimated 12-16% of global food production
• many fall short of their physical and economic targets
• they have led to the loss of forests, wildlife habitat, and aquatic biodiversity. Efforts to counter their impact have met with limited success
• estimates suggest that some 40-80m people have been displaced by dams worldwide, yet mitigation, compensation and resettlement attempts are often inadequate.

It is almost always the most marginal members of society who are harmed by dams.

"Little or no meaningful participation of affected people in the planning and implementation of dam projects has taken place", the commission says.

Other methods available

"The direct adverse impacts of dams have fallen disproportionately on rural dwellers, subsistence farmers, indigenous peoples, ethnic minorities, and women."

The WCD says there is far greater scope for using alternative ways of meeting people's needs, including renewable energy, recycling, better irrigation, and reducing water losses.

The site of Turkey's planned Ilisu dam

It is concerned about the loss of cultural heritage involved, and criticises the environmental performance of large dams.

It says rotting vegetation trapped underwater releases carbon dioxide and methane, both potent greenhouse gases, and that this can cause more pollution than generating electricity by burning fossil fuels.

Professor Asmal told the launch of the WCD report: "We reviewed alternatives. We balanced ideal against possible, and made our decision to sign this report with confidence.

Reparations demand

"We exclude only one development option: inaction. The cost of conflict is too high."

Patrick McCully, of the International Rivers Network, which works to link human rights and environmental protection, told BBC News Online: "The WCD largely vindicates what critics have been saying for years.

"It recognises the legitimacy of claims for reparations, and we want a moratorium on all large dams until those reparations are paid and the commission's recommendations implemented.

"And we want a halt to work on all dams under construction until they've been properly reviewed."