Environment : Fury Greets Chile’s Plan for a River : A huge hydroelectric dam threatens a way of life for the Pehuenches people. It symbolizes the struggle between development and preservation.

In the mountain watershed of the Upper Bio-Bio River dwell wide-ranging communities of Pehuenches, the Araucaria Pine People. When autumn unfurls the cones of the araucaria pine, families move through the woods gathering its nuts, an important part of their diet. They cherish and protect the stately tree almost as kin.

“To cut down an araucaria pine is like putting a mother to death, because that is what feeds our people,” explained Jose Antolin Curriao, a Pehuenche chieftain. Such ancient traditions may soon be tested in a time of change on the Bio-Bio.

Curriao and other Pehuenches are alarmed by dam construction on the river, fearing that their homeland of wooded mountains and roaring rivers, the essence of their culture, will be spoiled forever.

After futile protests and failed legal suits by opponents of development, workers and machines already are building the Bio-Bio’s first hydroelectric dam near this village, 300 miles south of Santiago. A much bigger second dam, still in the planning stages, would displace some 1,800 Pehuenches from their ancestral lands, their supporters say.

“Our community would disappear,” said Curriao, 60. “We want to follow the example of our ancestors. We don’t want to disappear.”

The Pehuenches are not the only ones worried about dam projects on the Bio-Bio. Sports enthusiasts, for instance, have flocked to the river in recent years because it provides a spectacular white water rafting experience. But its most thrilling rapids will be inundated if the second dam is built.

Ecologists, meanwhile, warn that important habitats for some species of fish and other wildlife are endangered by the dam projects, which also will put pressure on the fragile alpine environment flanking the river. University engineers who have studied the area say dams could disrupt the ecological balance of the whole Bio-Bio basin, one of Chile’s most important river systems.

An environmental organization called Action Group for the Bio-Bio is leading the campaign against the hydroelectric projects, and the Bio-Bio has become a prime symbol of the contest between economic development and environmental preservation in South America.

A couple of decades ago, few people in South America worried about protecting wilderness areas from the onslaught of development. That was a problem for North America, where vast natural tracts had been tamed in the name of progress. The process was still young in the southern reaches of the hemisphere; the desire for development overshadowed environmental cautions here. In recent years, however, South Americans have awakened to the dangers of degrading their natural environment as environmental and conservation movements have gained increasing strength and influence.

The shrinking Amazon rain forest has received much of the attention, but Amazonia is not the only part of South America where nature is in trouble. From the majestic Sierra Nevada de Santa Marta in Colombia to the chill forests of Tierra del Fuego, ecological damage is advancing at often alarming rates.

There is so much wilderness in South America that it sometimes seems hard to focus on piecemeal destruction and localized threats. In southern Chile, hydroelectric dams on several formerly pristine rivers are a widely accepted part of this country’s impressive development thrust.

The Chilean economy has grown at an average of more than 6% a year for the past decade. More energy is needed to keep the economic dynamo turning, and the southern rivers are an abundant source of power.

Meanwhile, however, development also is beginning to pollute the clear waters of many southern Chilean lakes. And chain saws are ripping through native forests, already shrunken by earlier settlement and exploitation.

The struggle over the Bio-Bio has become an emblematic showdown partly because it is a historic frontier as well as a strikingly beautiful river that tumbles down jagged Andean canyons in a torrent of blue crystal and snow-white froth. It also stands out because the fate of a unique native culture may be at stake.

The Pehuenches are among Chile’s poorest people, but their culture is rich in traditions rooted in the Andean lands where they gather nuts, herd flocks of sheep and goats, and grow wheat and other grains. They belong to the Mapuche nation, which kept Spaniards and Chileans at bay along the Bio-Bio frontier until the 1880s, when an military offensive against the Mapuches opened the way to settlement south of the river.

For most of this century, southern Chile developed slowly. But a national push for export growth in recent years has brought rapid growth in the south’s agricultural, fishing, fish-farming, wood and cellulose industries.

Endesa, a formerly government-owned power company that was privatized in 1988, has been keeping pace with development by increasing the generation of electricity. And the Upper Bio-Bio River, with its huge hydroelectric power potential, is a resource that Endesa wants to exploit.

Construction on the Bio-Bio’s first dam, called the Pangue, began in 1993 and is scheduled to be finished in 1997. It is budgeted at $470 million and will produce 450 megawatts of electricity. Its reservoir will cover 1,200 acres, flooding nearly nine miles of the river’s course, including several miles of scenic and raftable rapids.

But hydraulic engineers at Chile’s University of Concepcion say the environmental impact of the Pangue dam may be greatest on the Lower Bio-Bio. Andrea Nardini and Hernan Blanco, engineers with a university environmental research center, say the dam may reduce the river’s flow to a trickle in some places on summer days. “To dry up a river means killing its ecosystem,” Nardini said.

In the upper Bio-Bio, the impact is clear. Pangue S.A., a subsidiary of Endesa that is building the dam, acknowledges that it will be “unfavorable” for some river fish, including two endangered species of native catfish. In a recently published brochure, the company also admits a “possible increase of erosion and deforestation in the basin” of the river because of increased water in upland areas around the dam.

Only a few Pehuenches will be displaced by the Pangue, but its influence on nearby native communities has been the subject of heated debate. The company brochure says the dam may lead to accelerated loss of Pehuenche cultural identity, if countermeasures are not taken, but argues that it will help relieve the extreme poverty of the communities.

Pangue S.A. says the project will provide up to 2,500 jobs at the peak of construction and the reservoir will be a valuable future center for income-producing recreation and tourism. In response to criticism, the Endesa subsidiary has created foundations for promoting community development and for ecological preservation.

“It is in the interest of Endesa that the environmental impact be the least possible,” said Esteban Skoknic, a company planning engineer.

The chieftains of two Pehuenche communities on the Upper Bio-Bio have taken jobs with Endesa and support the dam project, but five others oppose it. “We don’t want to work for Endesa,” said one, 82-year-old Manuel Neicuman. “We want them to leave our lands alone so that we can pass them on to our sons.”

Neicuman, Curriao and three other Pehuenche chieftains gathered on a recent Sunday at a cabin downstream from the Pangue construction site. With them was Rodrigo Valenzuela, an anthropologist with the Action Group for the Bio-Bio. As the chiefs drank red wine and ate spoonfuls of spiced and coagulated goat blood in preparation for a late outdoor lunch of roasted goat, Valenzuela told a visitor that converting Pehuenche men into low-paid construction workers would unravel their cultural link to the land.

“To the extent that the Mapuche loses his ties to the earth, he is losing part of his identity,” the anthropologist said.

Pangue is more than one-third finished and impossible to stop, its opponents concede. Preliminary plans for the second Bio-Bio dam, called Ralco, have recently been submitted by Endesa for consideration by the National Energy Commission.

Ralco’s reservoir would cover more than 8,000 acres, dwarfing the Pangue lake. Valenzuela said Ralco would displace 300 Pehuenche families; Skoknic said Endesa estimates that 90 families would have to be moved.

But Valenzuela emphasized the impact would not be limited to displaced families. With Ralco, much more of the Bio-Bio’s beautiful and ecologically unusual canyons and valleys would be inundated, as would those of some tributary rivers. With new roads, land companies would buy up acreage and lumbering would spread into previously inaccessible areas, he said. More roads, more construction jobs and more outside influence would undermine Pehuenche culture.

“In economic, social and cultural terms it is the end of a people, its extermination,” said Valenzuela.