FERNDALE, Wash. — At age 94, Mary Helen Cagey, an elder of the Lummi Indian tribe, has seen a lot of yesterdays. Some are ripe for fond reminiscence, like the herring that used to run rich in the waters here in the nation’s upper-left margin, near the border with Canada. Others are best left in the past, she said, like coal.

The Westshore coal terminal in British Columbia. As demand declines in the United States, coal companies want to build six terminals on the West Coast for export.

“I used to travel into Bellingham and buy my sack of coal,” she said, standing in sensible shoes on a pebbled beach at a recent tribal news conference, talking about her girlhood of rural subsistence and occasional trips to the nearby market town. The idea that coal producers would make a comeback bid, with a huge export shipping terminal proposed at a site where she once fished, called Cherry Point, is simply wrong, she said. “It’s something that should not come about,” Ms. Cagey said.

Many environmental groups and green-minded politicians in the Pacific Northwest are already on record as opposing a wave of export terminals proposed from here to the south-central coast of Oregon, aiming to ship coal to Asia. But in recent weeks, Indian tribes have been linking arms as well, citing possible injury to fishing rights and religious and sacred sites if the coal should spill or the dust from its trains and barges should waft too thick.

And as history has demonstrated over and over, especially in this part of the nation, from protecting fish habitats to removing dams, a tribal-environmental alliance goes far beyond good public relations. The cultural claims and treaty rights that tribes can wield — older and materially different, Indian law experts say, than any argument that the Sierra Club or its allies might muster about federal air quality rules or environmental review — add a complicated plank of discussion that courts and regulators have found hard to ignore.

Lummi tribal leaders recently burned a mock million-dollar check in a ceremonial statement that money could never buy their cooperation. Last month, the Affiliated Tribes of Northwest Indians, a regional congress of more than 50 tribes in seven states, passed a resolution demanding a collective environmental impact statement for the proposed ports, rather than project-by-project statements, which federal regulators have suggested.

Leaders of the Columbia River Inter-Tribal Fish Commission, which focuses on fishing rights, said in a statement in support of the resolution that moving millions of tons of coal through the region could affect a range of issues, like road traffic and economic life on the reservations, not to mention the environment.

“It brings another set of issues to the table,” said Gov. John Kitzhaber of Oregon, a Democrat who earlier this year asked for a broad federal environmental review that would examine implications of the coal plan from transit through the region by train or barge to the burning of the coal in China. The tribes, Mr. Kitzhaber said, have now added a voice that even a governor cannot match. “It definitely increases the pressure,” he said.

Coal producers across the nation have been wounded by a sharp drop in demand in the United States — down 16.3 percent in the period from April through June, compared with the same period in 2011, to the lowest quarterly level since 2005, according to the most recent federal figures. With prices falling and abundant supplies of natural gas flowing because of new fields and drilling technologies, especially hydraulic fracturing, or fracking, many electricity producers that can switch are doing so.

That has made coal exports, which have increased this year in every region of the country except the West, according to federal figures, even more crucial to the industry than they were when the six terminals on the Pacific Coast were first proposed. Jason Hayes, a spokesman for the American Coal Council, said that with coal-producing nations like Australia and Indonesia competing for Asian markets, a roadblock on the West Coast is an issue for the entire American economy.

The first public hearings for the terminal projects, conducted by the Army Corps of Engineers, are set to begin this month in Bellingham, near the Lummi reservation.

“The people that can produce efficiently and can ship quickly and reliably — those are the big things — they are going to be the ones that are chosen for being reliable business partners,” Mr. Hayes said. “If we can build the ports on the West Coast, then it just becomes that much more reliable.”

But by coincidence of history, geography, culture and law, the West Coast, especially Washington and Oregon, is also a center for Indian tribe muscle, legal scholars said.

Although many tribes around the nation received rights to hunt and fish in the treaty language of the 1800s that consigned them to reservations, few places had a focus on a single resource — fish, especially from the Columbia River and its tributaries — that tribes here did. They also, crucially, persisted in using the resources that the treaties had granted them; fishing did not become a hobby or a cultural artifact.

Then, in the 1970s, when the Indian rights and environmental movements were both surging, tribal timing was fortuitous in pushing court cases that reinforced their claims.

“They made really good use of those rights, and have become major players,” said Sarah Krakoff, a law professor at the University of Colorado who teaches Indian law and natural resources law. Tribal rights have been a cornerstone in the long battle over restoring salmon stocks in the Columbia River. This year, one of the biggest dam removal projects in the nation’s history reached a milestone when a section of the Elwha River near Olympic National Park in Washington was restored to wild flow, with fishing rights an important driver in the process.

Coal has also become an element in the presidential race, as energy executives have poured tens of millions of dollars into campaigns backing Mitt Romney, the Republican candidate, and accusing the Obama administration of harboring hostility to coal through tightened air pollution rules.

An executive order dating from the administration of Bill Clinton could give further ammunition to Northwest tribes in their coal fight, Professor Krakoff and other experts said. The order directs federal agencies to allow tribal access to sacred sites and to take into account religious practices in federal decision making.

Lummi leaders, in the protest this week where Ms. Cagey spoke, said the Cherry Point site in particular — though partly developed years ago by industry, with a major oil refinery nearby — is full of sacred sites and burial grounds. The tribe’s hereditary chairman, Bill James, said in an interview, however, that the tribe would not reveal the locations of the graves for fear of looting.