There were a couple of new fellows around the pool tables at Curley's Lounge the other night. They played well and they stayed longer than most of the local people, and Sue Dutson shook her head and sighed. "Oil riggers," she said. The invasion is beginning.

First came the geologists, scholarly types who mostly kept to themselves after hoisting a few in Curley's or in Delta's other beer-only bar. Then there were the surveyors and the engineers, and residents noticed land prices were going up. Now there are the oil riggers, and pretty soon there will be electricians and military men and a great many construction workers and families for all of them.

The Delta area now has 2,000 people, but it will have 50,000 by 1988.

"I'm scared silly," said Mayor Leland Roper.

The MX missile is coming to Delta, if it goes anywhere, and so is oil drilling and the nation's largest coal-fired power plant, all at the same time. But the town's worries are not unique.

In small, placid communities in most of the wester desert states, lots of people are beginning to spend vast sums of money to dig and process and sell energy. And for the first time in a long history of boosting any kind of development, this traditionally conservative region is feeling a bit uneasy at the prospect of guaranteed growth.

There is oil shale in Utah, Colorado and Wyoming, enough for the extraction of 2 trillion barrels of crude, or six times all the proven oil reserves. on earth. There are tar sands in Utah, 93 percent of the nation's deposits, that could yield 30 million barrels of oil, and more in Wyoming.There is uranium here for the taking, and hot water and sunshine and wind, and there is lots of coal, too, so much that anyone who says he has measured it all is lying.

Maybe 2 million new people are coming to the West to get in on all of this, according to Department of Energy Estimates. It means jobs for traditionally depressed areas, rural growth for states where people have clustered in cities, and a very great deal of money. But it's coming so fast that it will also mean slag heaps, smokestacks and speculators, and boom towns of trailer parks. And these add up to utter transformation of local schools, entertainments, police and fire and hospital needs and small-town life in general.

It also means digging up a lot of semi-desert land and using awesome amounts of water for new purposes when there isn't enough to go around right now.

In Utah, Gov. Scott Matheson thinks federal agencies promoting development don't know what they're doing to his state. "The Department of Energy has a long way to go to get the right perspective," he said in an interview. "They just don't understand the impacts here."

Neither, he said, do the departments of Agriculture, Defense, and the Interior, which are also involved. "None of them are thinking about the fact they're all coming in here at the same time."

This is a new attitude for Utah, a thinly populated and socially very conservative state where the population is 70 percent Mormon. Traditionally Utahans have had large families, but young people tend to leave in order to find jobs and opportunity. Development to bring in jobs has always been top priority for any Utah politician, and it still is in many quarters here.

Now, however, Matheson is looking around for weapons he can use to slow things down, and even the boosters are studying ways to ease the impact.

Water problems are a good example. The massive $8 billion Intermountain Power Project, the nation's largest coal plant, will be built on a featureless desert spot 10 miles out of Delta, toward Lynndyl. The site was chosen after environmentalists objected that its coal boilers would foul the parkland atmosphere around its original location in southeastern Utah.

Owners of the 3,000-megawatt facility went shopping here for rights to the water they will need to cool those huge boilers, water that now irrigates crops in the area.

Jim Nelson of Lynndyl was one rancher only too happy to sell some of his water rights to IPP. For each acre-foot of water (enough to cover an acre of land one foot deep) that was worth about $200 ordinarily and serves an average family's household needs for one year, IPP paid him $1,750. "I got about $3 million," Nelson said over a beer at Curley's. "The land I was irrigating is pretty marginal anyway; never did make nothin' off it. The water rights were worth more than the whole damn place."

IPP got the water it will need from Nelson and other Delta area farmers because it could pay far more than any other use warranted. But nobody has figured out what this will cost Utah in crops or livestock.

Similarly, the Defense Department sent Air Force captains and colonels to Delta to explain why the MX is necessary and to promise that it won't interfere with the grazing rights or mining claims. But much more than that is involved. "The first meeting was chaos," recalled Mayor Roper. "Things got out of hand and there was a lot of shouting, everybody worried about their own thing. Biggest crowd I ever saw in this town."

As now planned, MX will involve 200 missiles shuttling among, 4,600 concrete underground shelters spread over 20,000 square miles of Utah and Nevada in sort of fishnet pattern. Depending on who's talking, construction spending alone will range from $36 billion to $50 billion of th $100 billion project.

Sue Dutson, owner, publisher, editor and chief reporter of the Millard County Chronicle, said she mistrusted the Air Force estimate that 17,000 workers would arrive at peak construction. The Alaska pipeline, she said, expected 5,500 but 22,000 came, five for every job available.

"We had our first purse-snatching ever last week," Dutson said, "and the first auto theft by a juvenile two weeks ago. The bars have had three fights in three months instead of the usual one a year . . . It's been a caring community where people know each other and look out for each other. That's the way of life we chose by living here and that's what we're going to lose."

There are a dozen real estate agents where there used to be one, and trailer parks adorn the town's eastern end. Delta's cement plant expects lots of business, but more cement will be needed than was used in the whole national interstate highway system. "I don't think there's enough labor or materials in the entire state," Roper said.

Gov. Matheson wonders if there is enough in the entire western region. "The state of Utah cannot be a major source of energy growth and . . . minerals while at the same time serving as a national sacrifice area for deployment of the MX missile," he said in a recent speech.

Matheson and other state officials complain they have very few weapons to fend off unwanted growth. Utah voters rejected a proposed state land use plan in 1974, "equating it with creeping socialism," one department chief grumbled. Federal agencies are required to consider such plans in letting mining or drilling rights.

Land ownership patterns in all these states make coherent planning almost impossible just when it is most needed. Interior owns two-thirds of the land in Utah -- and similar proportions in other western states -- because nobody wanted the arid scrubby hills back when the feds were giving it away. The federal land includes 90 percent of all western uranium reserves, 35 percent of the region's coal, and 75 percent of the nation's synthetic fuel resources.

But the state owns small 160-acre patches in a buckshot pattern all over the federal lands, areas reserved for school districts long ago. The regulation of farmers' grazing and water rights along with miners' mineral and other leases already gives everyone headaches, and things only get worse with new projects.

Utah's tax structure forbids counties to share the taxes they collect from out-of-town projects like IPP with the affected towns, which are legally separate entities. State regulations, designed to promote development, make it relatively easy to win drilling and mining permits.

Matheson does have one weapon in the state water engineer, who must certify that enough water exists for any major new project. The Air Force has asked for 50,000 acre-feet for the MX. "We're doing studies to see if it's there," Matheson said. "If it isn't, we could refuse to appropriate it."

Similarly, each barrel of shale oil requires 3.6 barrels of water in its productions, and the National Energy Security Act set a goal of 400,000 barrels of shale oil from the Colorado-Utah-Wyoming area by 1990. The water requirement, weak and subject to court battles though it is, is "the best tool we've got to manage our future," Matheson said.

One of Utah's development boosters concerned with growth is state Sen. Thorpe Waddingham, who engineered a contract in which the Intermountain Power Project pays the state $2.8 million for school system impact and $90,000 for studies. "But that's just a start," Waddingham said. "If it was in my by-God power it would apply to the federal government in spades." iHe plans legislation that would set up a required contracting formula for any development project coming into Utah.

"Left to our own devices we wouldn't be doing all this at once," he said. "If national priorities require this development, then the impacts become a national responsibility."

But he's not worried about development overload. Land speculation "saved lots of small farmers from being squozed out by big corporate owners," he said. "If we can do some planning we can handle everything but the MX with a minimum of pain . . . . I prefer the alternative of coping with growth to coping with depression."

Another booster is Herschel Hester, head of the Utah League of Cities and Towns." "Instead of seeing mobile homes as a tin city to set off near the railroad tracks, we'll have to look at them as an integral part of the community," he said. His group is helping local leaders think in terms of school buildings with removable wings that can be converted to other uses when the construction booms end. Model zoning laws are being rushed into print.

"What I want to know is whether the Environmental Protection Agency is going to revise Utah's sewer construction money to reflect these pressures," he said. "We're glad to have the growth -- after all, it's not all going to be here on Monday and eventually people will wonder why we didn't do it sooner."

The state's small community of environmental activists is unconvinced. "People have been led to believe they can have it all, jobs and plants and still maintain their way of life," said Nina Dougherty of the Sierra Club. "They can't." The club's conservation chairman, James Catlin, argues that only low-paid and unskilled jobs will come with the growth and that far too many power projects are planned than any national energy demand figures can justify.

"The state believes you can hyper-plan your way out of all this, subsidize development with federal money. But there's no example of it ever working," he said.

Mayor Roper of Delta, a tall, crewcut Mormon who resembles Lyndon Johnson, spent most of his life as an automobile mechanic and is worried that his town hall is full of equally amateur managers. "We're a year behind in planning already," he said. He just doubled the police force to four members and has begun to think about building a jail. "I just hope we survive all this," he said. CAPTION: Picture 1, Jim Nelson was paid $3 million by a power project for the water rights to his ranch near Lynndyl, Utah. By Jane Beckwith for The Washington Post; Picture 2, MAYOR LELAND ROPER . . . "I'm scared silly"; Illustration, no caption, By Pat Bagley -- The Salt Lake Tribune