The massive Willow oil project on Alaska's North Slope can move forward, a federal judge in Anchorage ruled Thursday.
U.S. District Court Judge rejected the claims of environmental groups, who argued that the ConocoPhillips project, which is located in the nature reserve, will damage the unique ecosystem of the Arctic.
The decision removes one of the last obstacles to the project, which would be the largest oil development on federal land in decades, and has become a flashpoint for climate activists.
Environmental groups said they plan to appeal.
[The U.S. Department of Interior's] decision to greenlight the project in the first place moved us in the opposite direction of our national climate goals, in the face of the worsening climate crisis, said an attorney with the environmental group Earthjustice, in an emailed statement.
The project is located in the National Petroleum Reserve in Alaska (NPR-A), a vast stretch of federal land the size of Indiana, which remains largely undeveloped and is an important habitat for wildlife including caribou, polar bears, and millions of migratory birds.
ConocoPhillips says it intends to resume construction work on 21 December, the start of the winter construction season.