SEATTLE — For centuries, Lummi tribal fishermen have harvested, dug up clams and fished for salmon in the tidelands and waters of northwest Washington state.

Now, the tribe says a proposed $700 million project to build the nation’s largest coal-export terminal threatens that way of life. The tribe last year asked federal regulators to deny permits for project, saying it would interfere with the tribe’s treaty-reserved fishing rights.

The Gateway Pacific Terminal, a venture between SSA Marine and Cloud Peak Energy, would handle up to 54 million metric tons of dry bulk commodities, mostly coal, at a deep water port at Cherry Point. Coal would be shipped by train from Montana and Wyoming for export to Asia.

If the Army Corps of Engineers, the federal agency overseeing the permitting process, finds that the proposed terminal would disrupt the tribe’s rights to fish in its traditional areas, it won’t issue permits. A decision is expected this week.

Like many tribes, the Lummi signed a treaty with the U.S. government in 1855 in which it ceded its land but reserved the right to hunt and fish in “usual and accustomed” areas.

“The Corps should honor the trust responsibility and deny the permit,” said Timothy Ballew, chairman of the coastal tribe, which has more than 5,000 members and one of the largest tribal fishing fleets in the country. “Our fishermen have fished there since time immemorial.”

Seattle-based SSA Marine says the Corps should find that project poses less than a minimal impact on the tribe’s fishing rights. The company contends that the most productive fishing for the tribe does not occur near the wharf. “They didn’t provide real evidence that they fish there a lot,” senior vice president Bob Watters said. The company also believes an environmental review that began in 2013 should be completed.

Earlier this month, however, project developers asked state and federal regulators to temporarily halt that environmental review while the Corps heard the Lummi’s request.

The terminal has become a lightning rod in the debate over whether the Pacific Northwest should become a gateway for exporting fossil fuels to Asia.

Environmental groups strongly oppose the proposal, worried about the greenhouse gases pollutants produced by burning coal and other issues such as increased train and vessel traffic. Meanwhile, some business and labor groups say it will create hundreds of jobs and generate tax revenue.

The Crow Nation of Montana, which has an option for ownership in the new terminal, backs the project as vital to its future. Lawmakers in Montana have led efforts to block the Corps from denying a permit until the environmental review is done.

If the federal agency denies the permit on the grounds of fishing rights, it wouldn’t be the first time.

“It’s fairly common,” said Robert Anderson, a University of Washington law professor who directs the school’s Native American Law Center. In 1996, the Corps denied a permit for salmon farm west of Lummi Island because it would interfere with tribe fishing rights. A federal court upheld that decision.

When federal agencies like the Corps issues permits, “they have an obligation to protect treaty resources. The Corps will have to take into account whether there will be an adverse effect on Indian treaty rights,” Anderson said.

The proposal would bring up to 487 vessels to a proposed three-berth wharf in an industrial zone about 100 miles north of Seattle. The company says the site presents a unique location, partly because it can accommodate the largest ships in naturally deep water.

The tribe says increased vessel traffic would disrupt fishing practices, as well as expose the region to potential oil spills, boat collisions, pollution and other problems.

Project developers say they would take measures to avoid or minimize impacts to tribal fishing, including setting up a system to let fisherman know about vessel positions and not allowing tug or tow operations due to tribal concerns about lost fishing gear.

The tribe says impacts can’t be mitigated and the terminal and activities would severely limit the ability of its tribal members to exercise their treaty rights.