The argument for HidroAysén was not frivolous. Chile is energy-hungry and chronically short of domestic power, and by the late 2000s two-thirds of Chileans lived in cities where air pollution regularly broke national standards, much of it from coal and petroleum-coke plants. Hydroelectricity from Patagonia's roaring glacial rivers promised clean, renewable power that could displace those plants, and the project's backers projected the country might save 500 million dollars a year. It drew support across the usual divides: the business community, the conservative president Sebastián Piñera who approved it, and even the former socialist president Ricardo Lagos, who called it necessary. The dams would create thousands of construction jobs and, supporters argued, benefit the whole country for generations. To a nation worried about blackouts and dependence on dirty fuel, it was framed as the responsible choice.

The opposition saw a different ledger. The dams would have flooded around 5,900 hectares and touched, directly or indirectly, six national parks, eleven nature reserves, sixteen wetlands, and dozens of protected sites in one of the largest untouched landscapes left on Earth. The endangered huemul, the South Andean deer that appears on Chile's own coat of arms, would have lost habitat. Critics also pointed out that much of the power was destined not for struggling households but for the copper mines of the north. And there was the matter of water itself: after Endesa was privatized in 1997, a vast share of Chile's water rights had passed into the hands of foreign investors, so that the rivers of Patagonia were, in a legal sense, no longer the nation's. For many Chileans, HidroAysén was not just an environmental fight. It was a question of who owned the country's wild water.

When the committee approved the dams in May 2011, ten votes to one abstention, the streets answered. Opposition that had hovered around 38 percent when the project was first floated climbed past 70 percent. Protests drew thousands; some turned destructive, injuring police and damaging property, though most were peaceful. Greenpeace Chile marched under the slogan to save Patagonia, and international groups including the Natural Resources Defense Council and International Rivers helped fund the legal and public campaigns. Celebrities lent their voices. Local officials, fearing the damage to their own districts, broke ranks to oppose it. The local people of Aysén, the gauchos and small ranching families along the Baker who had built quiet, self-sufficient lives, stood to be displaced, and they said so. The pressure was relentless and it did not let up.

The project died slowly, on paperwork and politics. The environmental impact assessment, first submitted in 2008, was repeatedly sent back as incomplete, criticized for failing to plan for the relocation of the families who lived in the flood zone, for thin analysis of the impact on water and wildlife. In June 2014 Chile's Committee of Ministers overturned the approval outright. The companies could have fought on, but the ground had shifted: cheaper solar and wind were transforming Chile's energy math, and the case for damming Patagonia weakened every year. In November 2017, Enel and Colbún finally ended it, dissolving their partnership and returning the water rights, calling the project no longer economically feasible. The Baker still runs free to the Pacific. For a movement that began with a bumper sticker, it was a total and improbable victory.