The Ninth Circuit Court of Appeals has ruled in favor of the US government allowing oil drilling to proceed in the National Petroleum Reserve in Alaska.

The Reserve was first designated a source of oil in 1923, and in 1976 management of the land was turned over to the US Department of the Interior, which was mandated to protect the area’s wildlife. The area is home to millions of migratory birds, beluga whales, and caribou, which are an important source of food for indigenous tribes.

The Bureau of Land Management (BLM) in 2012 issued a combined Integrated Activity Plan (IAP) and Environmental Impact Statement (EIS) regarding the management of the land and its resources. In 2016 ConocoPhillips found a new source of oil in the reserve that could bring up to an additional 130,000 barrels per day. The company currently runs one drilling operation in the Reserve, is building a second operation, and has drawn up plans for a third.

A coalition of environmental groups brought suit in district court, claiming that the discovery required that the BLM perform a new site-specific analysis to consider the harm caused by the new project. The district court initially issued a summary judgment in favor of the defendants.

The Ninth Circuit affirmed the lower court’s judgment in its Thursday ruling. It held that the government can issue a single document that serves as both an overall management plan for the land as well as a site-specific analysis of individual projects within the land, and that the 2012 document fulfilled the National Environmental Policy Act (NEPA) requirement of preparing an EIS for lease sale of land, despite the fact that the study was completed four years prior to the new oil discovery.