The department’s Bureau of Ocean Energy Management (BOEM) issued the approval for the Liberty Oil and Gas Project, which is expected to unlock an estimated 80-150 million barrels of recoverable oil from the Liberty field.

The Liberty field is claimed to be the largest light-oil reservoir to be developed on the North Slope, according to Hilcorp Alaska and its partners BP and ASRC Exploration (AEX).

Once developed, the Liberty Oil and Gas Project will become the first ever oil and gas production facility in federal waters off Alaska.

US Interior Secretary Ryan Zinke said: “American energy dominance is good for the economy, the environment, and our national security.

“Responsibly developing our resources, in Alaska especially, will allow us to use our energy diplomatically to aid our allies and check our adversaries. That makes America stronger and more influential around the globe.”

As per the development and production plan, Hilcorp Alaska intends to construct a nine-acre man-made gravel island nearly 32km east of Prudhoe Bay, in the 19ft shallow waters of the Beaufort Sea.

The facility for the Liberty Oil and Gas Project would be almost same as the Spy Island, Northstar Island, Oooguruk Island and Endicott Island oil-and-gas-producing artificial islands that are currently operating in the area’s state waters.

In August, BOEM after examining the potential environmental impacts caused by the Liberty Oil and Gas Project and a range of alternatives for its execution, identified one of them as the preferred alternative. The EIS approved the idea of constructing a self-contained drilling and production facility on a gravel island with a pipeline to shore.

DOI said that BOEM will continue to work with Hilcorp Alaska to make sure that all appropriate safeguards are applied during the project execution.

DOI Land and Minerals Management Assistant Secretary Joe Balash said: “There are already four other gravel-island facilities off the North Slope, and we consider Hilcorp’s plan to represent a relatively conservative, time-tested approach toward offshore oil and gas development.

“Using input from North Slope communities, tribal organizations, and the public, we have developed a robust set of environmental mitigation measures and safety practices that will be applied to this project.”