Also absent were sisters Berta and Nicolasa Quintremán, symbols of the protracted legal battle waged by 11 of the 92 Pehuenche indigenous families who were relocated due to the flooding of their land.

The 11 families fought the Spanish power company Endesa to defend their traditional lands, where their ancestors lived and are buried, until they finally reached an indemnification agreement last year with the Chilean state.

The socialist Lagos, who visited the dam on Sep. 10 and met with the Pehuenche families, announced last Friday that he would not attend the ceremony because he had other commitments.

Economy Minister Jorge Rodríguez was the highest-ranking government official present on Monday.

The conflict over Ralco actually dates back 15 years, to the 1989 announcement that four dams would be built on the Bío-Bio River, one of Chile's largest rivers.

On Mar. 6, 1997, then-president Frei inaugurated Pangue, the first of the four hydroelectric plants.

The National Energy Commission decided later to cancel the construction of the other two dams. Meanwhile, in 1999, Endesa acquired a controlling share in Enersis, the holding company that owns the Pangue and Ralco plants.

"The inauguration of Ralco puts an end to a sad, conflict-ridden chapter involving the country's indigenous, environmental and energy policies," said Larraín, a former presidential candidate.

The conflict affected "indigenous communities, grassroots movements, many government officials, business sectors, and even the government at the international level," she added.

Ever since the construction of Ralco was announced, activists have protested that the project contravened the 1994 environment law as well as the legislation on indigenous rights passed in the early 1990s, because the land in question was the ancestral property of the Pehuenche Indians -- a subgroup of the larger Mapuche indigenous community.

Indigenous people, mainly Mapuches, represent at least one million of Chile's population of nearly 16 million.

Environmentalists accused former president Frei of favouring business interests and a 570-million-dollar investment at the expense of the territorial and cultural rights of the indigenous families, which are recognised by Chilean law, and the preservation of endangered species and an ecosystem that was unique in the world.

By applying pressure, the Frei administration secured approval of the project by the National Environment Commission in 1997 "on the basis of insufficient environmental impact studies and technical irregularities," said Larraín.

Environmentalists also accused Frei of "delegitimising" the National Commission for Indigenous Development, which represents the country's ethnic minorities, by forcing two of its chairs and two advisers to resign in order to ensure that it would also approve the controversial hydropower project.

Because of the stubborn resistance put up by the elderly Quintremán sisters and other Pehuenche families, the case made it all the way to the Inter-American Court of Human Rights, and a lawsuit was filed against Endesa in Spain on charges of "ethnocide".

The support that the Chilean state gave Endesa, "ignoring its obligation to enforce the law on indigenous rights and to guarantee the protection of their lands, was the worst aspect of these 15 years of conflict," Isabel Lincolao, the head of the National Network for Ecological Action (RENACE), said in an interview with IPS.

"The Inter-American Court ruled against Chile in 2003, but by then the dam was already 90 percent finished," said the activist. "So the Lagos administration had to redress what the Frei government had done, and compensate the Pehuenche families for something that was already a fait accompli."

The compensation included relocation to 1,200 hectares of land elsewhere and payments of 300,000 dollars to four families who finally agreed to leave their land.

The compensation was mainly paid by the state from public funds. "Chilean taxpayers had to pay more than half of the reparations, instead of Endesa," complained Larraín.

The controversy over Ralco calmed down somewhat when thermoelectric plants fired by natural gas imported at low price from neighbouring Argentina began to be built in Chile. However, supplies of that fuel have been rationed since late 2003 due to an energy crisis in Argentina.

"Perhaps Chileans understand that because of Chile's energy crisis, the completion of Ralco must be seen as a lesser evil," Manuel Baquedano, president of the Institute of Political Ecology (IEP), remarked to IPS.

But the plant "is essentially the expression of unbalanced development, that favours economic interests over the needs of the community," he argued.

In Baquedano's view, a commitment is needed to ensure "that there will never again be a 'Ralco'," and that the damages to the ecosystem posed by large dams will be avoided by developing renewable, sustainable energy sources, like solar, wind, geothermal and wave energy and small hydropower dams.

Endesa has a different take on the situation. The company's executives took advantage of the inauguration of the dam to urge the Chilean government to send out "clear signals" that it will support the development of new hydroelectric projects, especially in the extreme southern part of the country, much of which is pristine wilderness.