Troubled Waters

Originally published in The Financial Times

Aaron Sanger grimaced at the sight of the tumultuous Río Quiroz, a 150ft-wide gush of glacial meltwater surging off Patagonia's Southern Ice Field. A pair of torrent ducks skimmed across its swirling waters, peering curiously at the steel cable and cage that hydroelectrical engineers had built four decades ago, which now sagged perilously close to the water.

Sanger, a campaigner for US-based environmental outfit International Rivers, knew a mistake could cost his life. A hundred yards downstream, the Quiroz emptied into a maelstrom even more ferocious: the Río Pascua, one of the fastest flowing rivers in Chile.

Checking the harness that secured him to a tree on the far bank, Sanger climbed gingerly into the rusted steel cage and gasped as the icy water surged to his waist. Then, his fellow hikers strained on the rope, hauled the cage free of the swirling waters, and bailed him uncertainly across.

I had come to Chile's Aysén province to hike with Sanger and a handful of environmentalists as they documented the plant and animal species found in the Río Pascua's watershed, which tumbles for 38 miles from Lago O'Higgins to one of the many fjords along Chile's southern coastline.

To the environmentalists, the mission was a race against time, for the Pascua is one of two rivers in southern Chile threatened by a vast hydroelectric project that would transform a pristine region rated by in-the-know outdoors enthusiasts and ecotourists as one of South America's last true wildernesses.

In May, the plan seemed set to go ahead, when Chile's environmental authority approved a study of the dams' likely ecological impact. Last week, however, a court in the city of Puerto Montt granted an injunction to the enviromentalists, delaying the project while it reviews the approval process.

Proposed by Endesa Chile, a former state-owned power company now owned by Italian and Spanish energy firms, the $7bn HidroAysén scheme is centred around the construction of five large dams on the Pascua and the nearby Río Baker, which will flood some 23 sq miles of forest.

Together with local partners, Endesa plans to build a 1,180 mile transmission line, much of it through temperate forests of a type found nowhere outside Patagonia. Protected by a logged corridor more than 300ft wide, the power line would become one of the world's longest clear-cuts.

The scheme would arouse less controversy in almost any other part of Chile. Officially known as Región XI, Aysén is sandwiched between the Andes and the Pacific, cut off from the rest of the country by fjords to the north and, to the south, by Patagonia's Southern Ice Field.

Until now, the sparsely populated region has been almost untouched by industrial development. The province's 92,000 residents - about two per square mile - wrest a tough living farming cattle and sheep in clearings hacked from the forest. A single road - the precarious, gravel-surfaced Carretera Austral - connects natural highlights that include temperate Valdivian rainforests and two continental ice sheets, the largest expanses of permanent ice outside Antarctica and Greenland.

Large swathes of biodiverse forest remain intact, offering habitat to rare creatures such as the torrent duck, river otter and culpeo fox. Dozens of national parks, nature reserves and other protected areas make it one of the most compelling eco-tourism destinations on earth.

Some 35,000 outdoors adventurers come to Aysén each year to fish its trout-rich rivers and to hike, bike or kayak among its hanging glaciers, peaks and white-water rapids. Walkers come to tramp Cerro Castillo's jumble of 2,700m basalt spires, nature lovers to observe rare deer at the Tamango national reserve, while climbers come to scale the 4,058m-high San Valentín.

"For now, the Pascua valley is pristine and intact," Sanger told me before the trip. "There are no paths or roads in the area, so we'll hike for a week without seeing any human activity. This might be our last chance to see the river in its virginal state."

We reached the Pascua's headwaters after a six-hour cruise on Lago O'Higgins, itself a gruelling two-day drive south from Coyhaique, Aysén's main city. Aboard a former naval vessel, we steamed among icebergs along Chile's frontier with Argentina, which bisects the lake's northeastern arm. Beneath the glacier-scythed flank of 1,800m Cerro Esperanza, we disembarked on a rocky, tree-lined shore, utterly alone in the Patagonian wilderness.

Endesa began evaluating the Pascua's hydroelectric potential in the 1950s, but technological limitations and the river's sheer remoteness halted any serious attempt to exploit its abundant flow. With few power sources of its own, Chile fell back on natural gas imported from Argentina, which it converts into electricity.

Since 2004, however, Argentina has struggled to supply its own market. With energy demand in Chile growing by 6 per cent a year, HidroAysén's defenders - who include Chilean President Sebastián Piñera - argue that the project will boost Chile's power supply by 20 per cent, sufficient to power economic growth for years to come.

Yet ecologists reel off a lengthy charge sheet of the damage the HidroAysén scheme is likely to cause, ranging from fertility loss in downstream soil to habitat destruction of endemic plant and animal species, such as the huemul, an Andean deer so endangered that its population has dipped below 3,000.

Activists believe the high-capacity power lines will affect 14 national parks or nature reserves, and could unlock a slew of other industrial projects. "Putting that transmission line up would halve the cost of new projects throughout southern Chile," said Ian Farmer, a British-born tourism consultant based in Aysén. "It could turn Patagonia into a vast factory for electricity."

In one opinion poll last month, 74 per cent of respondents said they believed the project should not go ahead.

Down in the Pascua valley, our expedition was making slow progress. Beside the river, the banks were densely covered with coihue and ñire southern beech, the undergrowth a barely penetrable mass of spiny calafate and michay bushes. The days began with the plaintive call of a black-throated huet-huet, the dawn chill soon burned off by Patagonia's penetrating sunlight as the eight-member group picked a route among thicket-packed gulleys. By dusk, sweat-soaked and exhausted, we slept under the brightest of starry skies. By the third day, we had climbed out of the lowland forests, rising through alpine meadows to a heather-and-moss heath laced by mountain streams of a dazzling purity. Above 700m, the vegetation gave way to lenga, another species of southern beech, the views stretching to jagged, snow-crested summits that whitened the horizon.

Wildlife grew more plentiful. We spotted the tracks of a culpeo fox, and froze as a huemul, an adult male, wandered casually from a copse. The birdlife, too, seemed more numerous: hawks, harriers and condors circled in the canyons, while the staccato drill of the Magellanic woodpecker, South America's largest, and the melancholic cry of the chucao, carried far over the slopes.

The court did not specify how long its injunction would last, but the ruling is being interpreted in very different ways by the opposing sides. The jubilant environmentalists claimed it was "the beginning of the end" for the project, while a lawyer for HidroAysén said it was a "routine step" and would not "alter the time frames we have for the project in the slightest". The consortium expects to publish details of the transmission line's exact route next month and to complete the first dam in just five years.

Our expedition's final leg lay across a 1,200m-high ridge of fissured granite, its clefts packed with snowdrifts and pooled meltwater. A dark-bellied cinclodes flitted on the naked rock; a pair of rare white-bellied seedsnipe whipped by on the wing.

From the windswept summit, we stopped to admire the Southern Ice Field's monumental glaciers, then began the final, challenging descent. As we neared the Pascua once more, the sound of a motor drifted up on the breeze, the first we had heard in a week. Across the valley, engineers were already cutting an access road in preparation for the dams' construction: its scar was dark, raw and forbidding.