The Northern Cheyenne Indians, who fought 100 years ago against Gen. George A. Custer to keep their land and preserve their way of life, and fighting again for the same reasons - bu this time the enemies are coal and power companies rather than the U.S. cavalry.

The reservation is the middle of one of the world's richest coal areas, and while other tribes like the Navajo int he soutwest and the neighboring Crow in Montana are to develop energy sources, the Northern Cheyenne want no part of it, despite get-rich-quick promises from the white man.

Instead, they are trying to block construction of two $1.4 billion coal-fired power plants of 760 megawatts each that are planned for the town of Colstrip, 13 miles from the reservations clean air laws to limit other planned energy development around their reservation so their air won't become polluted. And the Cheyennes also are resisting industry pressures for development of their own enormous coal reserves.

As the United Mine Workers strike in the East has raised questions about the reliability of coal as an energy resource, Eric Metcalf, an official for a tribal research project to assess energy impacts, in quick to note that this area of southeastern Montana and adjoining parts of northern Wyoming and the western Dakotas contain about half the nation's mineable coal reserves.

"We're an island in the midst of coal leases," says Metcalf.

Allen Rowland, president of the Cheyenne Tribal Council, says he wants to avoid the pollution, population growth and other social impacts that wold come with massive energy development in the area. "We are in a fight for survival as an Indian people," he says.

But the Cheyennes' desire to preserve their way of life and air quality is putting the tribe at odds with major coal and power companies, and even the Crow Indian Tribe, which wants to develop its coal.

If the Cheyennes have their way, "it could halt all coal development, power plants and even timbering in the area," claims John Peterson, an attorney for Montanna Power Co., which wants to build the two power plants at Colstrip and already operates two others and a strip mine there.

As their main weapon, the Cheyennes are using a provision of the nation's clean air laws to try to keep their pristine air quality from deteriorating. The tribe has become the first local government in the nation to invoke the law's provision.

The provision, called the "prevention of significant deterioration of air quality," was written into law by Congress last year. The law gives immediate protection to air in most national parks and wilderness areas, and allows governmental bodies and Indian tribes to designate areas where significant air pollution won't be allowed.

The Cheyenne clean air designation, puts the reservation in the top "Class 1" category that allows for only minor additions of pollution to existing air quality.

CLean air is one of the few things that the nearly half-million-acre Cheyenne reservation of about 3,000 people has going for it. It has headquarters here at Lane Deer, a town of dirt streets, a handful of stores and many mobile homes. The Cheyennes harvest some of the pine trees that dot the sandstone cliffs, have a small sawmill and raise cattle. There is poverty, with unemployment estimated at $1,700 a year.

Many whites wonder why the Indians don't want to change all that by developig their coal. The reservation is atop 23 billion tons of coal, of which about 5 billion tons are economiclly recoverable. In the 1960s the tribe leased out the mineral rights to more than half the reservation to major coal companies and individual speculators.

As the tribe learned of the potential impact of the development and began to feel it "got taken" at 17-cents-a-ton royalites, minds changed about mining, says Richard Monteau, director of the tribal research project on energy. The interior Department has halted the coal companies from proceeding on the leases without consent of the tribe, which isn't likely to come.

By opting for preserving their existing air quality under the Clean Air Act, the Cheyennes have in effect ruled out any significant strip mining of their own coal reserves. They have not taken an official position, but because of pollution from coal dust, the air quality rules would prevent anything but the smallest surface mine on their reservation, tribal officials say. Instead, the tribe is investigating developing the less-polluting oil and gas potential of the reservation, Monteau says.

Recently, the Cheyennes, along with a neighboring rancher group, won a significant court battle built. Earlier this month, a state judge, citing various procedural errors, overturned construction permits granted for the Colstrip plant by state agencies. Montana Power Co. has appealed the case to the state Supreme Court.

Tribal President Rowland says: "People say we're just holding out for more money. It's not at all . . . We put more value on the air and land." Rowland says that one of his main concerns is that the Cheyenes not become a minority on their own reservation because of the influx of people due to energy development. Today, 98 percent of the reservation is Indian-owned, much higher than for most tribes, which often sell or lease their land.

One reason for such attaachment to the land is that the Cheyennes fought long and hard for it in the 19th century. Cheyennes and Sioux defeated Custer in 1876 in the Battle of the Little Big Horn not far from here, and later the Cheyennes were taken to Oklahoma Indian territory. After a year of malnutrition, diseases and lack of game, 300 Northern Cheyennes fought off and ended 12,000 U.S. troops to return to their land here on the Tongue River, where they were finally allowed to reamin.

"We've got our land," says Rowland. "We've got no other place to go. This is it, And we want to keep it just the way it is."

But energy companies complain that the Cheyennes' protection of the air quality will affect not only the reservation but also could limit or prohibit many development plans in this entire coal-rich region.

As a start, the Cheyennes are trying to use the Class 1 designation to prevent construction of two power plants at Colstrip planned by Montana Power, Pacific Power & Light Co. and other West Coast utilities. The Indians say the plants shouldn't be built because they would pollute more than the Class 1 air designation for the reservation allows; the utilities claim otherwise. An Gavironmetal Protection Agency decision on the matter is expected soon.

Besides Colstrip plants, there are surface coal mines planned in every direction around the tribal lands, and there is talk of more power plants and coal gasification facilities being built. Worried that the Cheyenne air quality protection might stop some of the development, major coal and power companies and the Crow Indian Tribe have united in a legal challenge to the Class 1 designation. The case is pending in a federal appeals court in San Francisco.

Montana Power Co. attorney Peterson argues that the Class 1 air designation gives the Cheyenne tribe illegal "extraterritorial power over the sites of our power plants and our lands and enables them to control development outside their reservation." Wyoming Governor Ed Herschler wrote the Cheyennes to say that the air quality designation could limit coal conversion plants being considered for the northern part of his state and the decisions "ought to be made by the people of Wyoming, not by perons in Montana."

At the nearby Crow Indian reservation, tribal chairman Forrest Horn complains that the Cheyenne action "could jeopardize our coal mining."

And several major companies, including a subsidiary of International Telephone and Telegraph Corp., fear that the Indians might stop them from building a major mine just south of the Cheyenne reservation on the cattle ranch of Marcus Nance.

Nance, spreading of the floor a map of his coal interests which he says are worth $10 million to him, says that the Class 1 designation "would stop the mine" and amounts to "denying me the right to my property without compensation. I should be able to lease my land if I want to."