ANCHORAGE, Alaska (AP) — Three Alaska Native tribes have sued to block what they say would be one of the largest gold mines in the world, arguing that federal agencies failed to properly analyze health and environmental concerns for the project in southwest Alaska.

Tribes from the communities of Kwethluk, Tuluksak and Bethel filed a federal lawsuit Wednesday challenging the adequacy of a 2018 environmental review by the U.S. Army Corps of Engineers and issuances of a key permit and lease by federal agencies for the Donlin Gold project.

The lawsuit, filed on behalf of the tribes by environmental nonprofit Earthjustice, claims the agencies failed to fully analyze potential harms and health impacts from a catastrophic spill and did not provide adequate protection for rainbow smelt, a subsistence food, from increased barge traffic related to the project, the Anchorage Daily News reported.

The lawsuit states the project has received the approvals needed for construction to begin but that construction has not yet started. The project is about 10 miles (16 kilometers) north of the Kuskokwim River community of Crooked Creek. Donlin Gold LLC, owned by subsidiaries of Canada-based NovaGold Resources and Barrick Gold Corp., manages the project.

Dolin Gold said in a statement that the federal permitting process was rigorous.

“Donlin Gold’s stakeholders fully believe that this lawsuit is meritless and are confident the actual record will once again fully support the agencies’ decisions,” the statement said. “In the meantime, the Donlin Gold team and the owners continue to advance remaining state permitting, as well as drilling and technical work, subject to Donlin Gold LLC Board approval.”

The lawsuit names as defendants the corps, U.S. Interior Department, U.S. Bureau of Land Management and agency officials. An Interior Department spokesperson declined to comment. A spokesperson with the corps in Alaska referred an email request for comment to the U.S. Department of Justice, which did not respond to an online request for comment.

The deposit contains 39 million ounces (1.1 billion grams) of gold — worth close to $80 billion at today’s prices. A 315-mile (507-kilometer) natural gas pipeline from the west side of Cook Inlet would supply a power plant at the mine. The project life is anticipated around three decades.

The project is on land owned by The Kuskokwim Corp., the area Alaska Native village corporation, and the mineral rights to the deposit are controlled by Calista Corp., the regional Alaska Native corporation.

The mine is expected to employ 3,000 people during construction and about 1,400 people during operations. Opposition has grown in recent years from tribes and other Indigenous groups that worry the project will harm fisheries, a primary subsistence resource for residents.