As  the presidency of Argentina’s Cristina Fernández de Kirchner enters its final days, her greatest – and arguably most controversial – legacy project is just getting under way in the remote grasslands of Patagonia.

Here, amid herds of wild guanacos, condor nests and the occasional rhea, a Chinese-financed team of engineers will soon be dynamiting hillsides and pouring millions of tonnes of concrete for two giant hydroelectric dams that will flood an area the size of Buenos Aires.

Although the environmental impact study for the $5.7bn scheme has yet to be announced and approved, preparatory work is already well under way beside the Santa Cruz river valley once explored by Charles Darwin. 

Dozens of huge Chinese dump trucks and drilling machines are now parked in the middle of the vast plain. Shafts and tunnels are being dug into the slopes near the main site. And a base camp – with canteens, game rooms and portable dormitories that still smell of fresh paint – has been established in the semi-wilderness.

The conditions make it tough. In winter, temperatures can fall below -20C (-4F) and the ground is often buried under snow.

“The main challenge is coping with Patagonia – because of the cold, the wind and the distances involved,” says Néstor Ayala, the chief of construction at the site. “If you are short a single screw, you have to go 300km to the nearest hardware store.”

A few hundred workers are living at the site already, but within a year Ayala expects this temporary community to grow into a small town of more than 5,000 people.

Cristina – as the president is best known here – will step down on 10 December, but the Kirchner name, fame and notoriety will live on in both the dam and its social, political and environmental consequences.

True to her Peronist ideals, it is an ambitious nation-building, job-creating edifice. With an installed capacity of 1.7 gigawatts, the hydropower plant will be the biggest solely inside Argentina (there are larger dams, but they cross borders and are shared with neighbours). Fernández has described it as “the most important hydroelectric project” in the country’s history.

Yet this is also a profoundly dynastic project. One of the two dams will be called the Néstor Kirchner, after the president’s deceased husband and predecessor in office. The region that will benefit most from the flood of hydropower cash and jobs is the Kirchners’ political heartland of Santa Cruz state. The president has a home in the nearest town, El Calafate, and owns several local hotels. Her sister-in-law Alicia has just been elected state governor and her son Máximo has secured a congressional seat here.

“People in Santa Cruz are grateful that Cristina put this place at the centre of political debate after decades of it being seen as the end of the world,” said local journalist Ernesto Castillo.

But approval is far from universal. Critics say the project is being rushed into being before the end of the president’s term despite its immense geostrategic and environmental implications.

Chinese banks are providing the financing: China Gezhouba Group will build the dam with an Argentinian partner Electroingenieria and then operate it for 20 years. After that, the dams will be handed over to the state government.

It is the biggest of several huge investments that were agreed last year in a summit between Fernández and the Chinese president, Xi Jinping. Other projects include two railways and a contentious satellite tracking base in Patagonia, which gives the Chinese military a space monitoring station in Argentina. There are also plans for China to build a nuclear power plant, although Fernández’s centre-right successor, Mauricio Macri, has pledged to review this decision.

Stronger links with China are in keeping both with the Peronist strategy of playing off superpowers against one another, and a more recent regional trend that has seen several governments in Latin America, including Brazil, Venezuela, Ecuador and Bolivia, forge closer ties with Beijing.

In the case of the dam project, this has prompted alarm bordering on xenophobia. In an echo of the “yellow peril” prejudices of the past, some in sparsely populated Patagonia fear an influx of Chinese settlers. These concerns are ill-founded. Only 150 Chinese engineers will work on the project, less than 4% of the entire workforce.

Of greater significance is the debate about whether Argentina is being sold short.

Ariel Slipak, an economist at the Moreno University, said the president was guilty of short-term thinking in the deals she struck with Xi that will ultimately prove no better than the country’s older unbalanced ties with the US and Europe. He believes China is financing the hydropower plant to ease energy shortages in Argentina so that it can import more oil from the country. The benefits, he said, would be for the business elite in both countries, while the consequences would be felt long after the change of president.

“Cristina’s legacy is to create a new relationship of dependency on China,” he said. “China is not looking for a quick profit here. They are making a geostrategic move to secure resources.”

In return, Argentina will get investment and another source of power – but not necessarily the one that suits its needs or geography.

Environmental groups believe that instead of a giant dam, it would make far more sense to develop alternative energies in a region that is famous for gusts.

“Santa Cruz could be the Kuwait of wind power,” said Emiliano Ezcurra of the Banco de Bosques (Forest Bank) environmental organisation. “Cristina could leave a legacy of breakthrough environmental technology. Instead, she’ll leave behind a horrible scar on our beautiful land.”

The greatest concern is the likely impact on wildlife and scenery. 

Santiago Imberti, a local conservationist, said the dam would flood the breeding and wintering sites of tens of thousands of birds, including the highly endangered hooded grebe – a native species of which there are only 800 left.

Conservation groups launched a legal challenge against the project in October. They claim it was launched without the necessary environmental impact assessment; that it violates the national park law, which prohibits developments in protected areas; and that it is contrary to the glacier protection law, which forbids any activity that threatens the nation’s ice fields.

Fears have focused on the Perito Moreno glacier, a world heritage site and one of Argentina’s best-loved tourist attractions. Located an hour’s drive from El Calafate, the blue and white forest of frozen and gnarled crags stretches from distant mountains down to the turquoise waters of Lake Argentino. Every two to 12 years, the glacier blocks the lake until it ruptures spectacularly, drawing hordes of visitors.

There have been worries that the dams could disrupt this cycle. Geraldo Bartolomé, a civil engineer, launched an online petition arguing that the constant lifting and falling of the reservoir water level would erode the ice bridge. After he collected more than 60,000 signatures, the dam’s designers reconfigured the project so that the reservoir would not connect to Lake Argentino. This should protect the glacier, but Bartolomé remains concerned that the project is being pushed through without due consideration for the consequences.

“No serious environmental study has been done,” he said. “I’m an engineer. I’m not against progress. But they have to prove they are not affecting the glacier.”

This is denied by Electroingenieria. But regardless of the impact on the ice, the controversy over the dams looks set to rage on long after Fernández leaves the presidential palace and moves back to El Calafate.

In the years ahead, Patagonia will be opened up like never before. More settlers will arrive. More accommodation will be needed. Roads will have to be improved. A new high-tension power transmission line will be necessary to link the hydropower plants to Buenos Aires, 1,900 miles away. Once these are in place, industrial farming will be more feasible, mining will be cheaper and investments are likely in other power plants.

For better or for worse, the “end of the world” will never be quite the same again.