The Joe Biden administration has approved the giant Willow oil drilling project in Alaska , angering climate advocates and setting the stage for a legal challenge.

The Willow project is a decades-long oil drilling initiative in the federally owned National Petroleum Reserve. The area where the project is planned is home to up to 600 million barrels of oil, although that oil would take years to reach the market as the project is not yet being built.

According to government estimates, the project would generate enough oil to release 9.2 million metric tons a year of carbon pollution, which would be the equivalent of adding 2 million gasoline-powered cars to the roads.

The approval is a victory for Alaska’s bipartisan congressional delegation and for a coalition of Alaska Native tribes and groups that hailed the drilling project as a much-needed new source of income and employment for the remote region.

What you need to know about the controversial Willow oil project in Alaska

But it’s a blow to environmental groups and Alaska Natives who opposed Willow and argued that the project would hurt the president’s ambitious climate goals and pose health and environmental risks.

Activism against it has grown online, where there are more than a million letters written to the White House protesting the project and a Change.org petition with millions of signatures.

Environmental advocates are expected to challenge the project in court.

Earthjustice, an environmental advocacy group, has been building a case against the project and intends to argue that the Biden administration’s authority to protect Alaska public land resources includes taking steps to reduce pollution. by carbon that warms the planet, to which, ultimately, the Willow Project would be added.

The president of Earthjustice, Abigail Dillen, criticized the government’s decision on Monday.

“We are too far along in the climate crisis to pass massive oil and gas projects that directly undermine the new clean economy that the Biden administration has promised to advance,” Dillen said. “We know that President Biden understands the existing climate threat, but he is passing a bill that derails his own climate goals.”

Willow Oil Project Details

The project was approved with three drilling rigs instead of two. In recent weeks, the Biden government had considered reducing the number of approved drilling rigs to two and increasing nature conservation measures to try to assuage concerns from climate and environmental groups about the project.

But ConocoPhillips and Alaska’s bipartisan congressional delegation lobbied the Biden White House and the Interior Department for months to approve three drilling rigs, arguing that the project would not be economically viable with two.

Ultimately, the government felt it was legally constrained and had few options to cancel or significantly scale back the project, which was initially approved by the Trump administration. The administration determined that, legally, the courts would not have allowed them to reject the project outright, two government sources familiar with the approval told CNN.

Many oil extraction leases at the site were decades long, which the government considered gave ConocoPhillips certain existing legal rights. Reducing the drilling rigs to two would have allowed the company to drill about 70% of the oil it was initially seeking.

Still, the final scope of the project will encompass 68,000 fewer acres than ConocoPhillips initially intended, according to the sources.