Identical signs at opposite ends of town, only a mile apart, tell travelers passing through this hamlet on the western slope of the Rocky Mountains that Parachute has 371 people living at 5,095 feet above sea level. m

But the signs, erected last fall, are already obsolete. The population in and around Parachute has doubled since the 1980 census. And the prospects are for thousands more to come, and stay, in the next few years.

This ramshackle town is perched at the edge of the world's richest deposit of oil shale, touted by leaders of government and industry as the best alternative to imported petroleum.

A half hour's drive up the canyon, on a lonely butte studded with juniper and pinon, Exxon has launched the Colony Development Project. The name is appropriate because the $3 billion facility is designed to extract 47,000 barrels per day of oil-like kerogen by 1985.

Nearby, Union Oil of California has begun construction of the first phase of a project that will yield 36,000 barrles per day by 1987 and up to 150,000 barrles per day at full capacity.

Across the river from Parachute, Exxon is building a new town on Battlement Mesa to house 2,000 workers who will be employed at the Colony Project when it reaches full capacity.

The new community eventually is to be home to 20,000 people, with a shopping center, offices, schools, churches and recreational facilities, all the modern conveniences that Parachute so far has avoided. Battlement Mesa is to be the biggest town between Denver and Grand Junction, a 250-mile stretch.

To the northwest, Gulf Oil and Standard of Indiana are testing a process they hope will produce 76,000 barrels per day of kerogen on a tract they leased from the federal government in 1974.

On a second federal lease to the northeast, a joint venture of Occidental Petroleum and Tenneco is building a $5 billion facility to process more than 100,000 barrles of kerogen per day by burning the shale in a series of huge caverns five stories high and 1,000 feet underground.

Fifteen miles from Parachute, the Paraho Development Co. has produced shale oil from the U.S. Naval Oil Shale Reserve since 1974 under a contract with the Pentagon. Paraho will build a 30,000-barrell-per-day plant near Bonanza, Utah, about 100 miles from here, next year.

In addition, Standard Oil of California and Conoco, the largest private holders of oil shale lands, plan a 50,000-barrel-per-day facility at Clear Creek to the southwest of Parachute.

Superior Oil, Cleveland Cliffs Iron Co., Multimineral Corp., Standard Oil of Ohio, Phillips, Sunoco, Equity Oil and a host of smaller oil and mining companies have projects at various stages of design and testing, all within a 100-mile radius of Parachute.

Beyond them are the engineering and construction firms, enviromental consultants, suppliers of steel and concrete, manufacturers of equipment for mining, retorting, refining and transporting the materials; highway and housing contractors; bankers, lawyers, and real estate agents, all trying to cash in on the multiplier effect of a multibillion-dollar investment.

Even the more cautious experts predict the industry will create 75,000 new jobs and a half-million boost in population on Colorado's western slope by the mid-1990's.

Job-hunters began drifting into Parachute last fall.As word of the boom spread, the flow increased. Last month, as the spring runoff swelled the creeks with melted snow from the mountains, the flood of immigrants began.

Even those who were lucky enough to find jobs had trouble finding a place to live. With the motels filled, available rental housing already leased and trailer parks crammed bumper to bumper, the new arrivals pitched camp wherever they could find a spot along the roads and creek beds.

Every day, seemingly from everywhere, more peopel arrive in search of work: in less than two hours, one could count license plates from 20 different states from coast to coast.

The new arrivals look for work during the day, driving from one construction trailer to the next. In the afternoon they sit in the doorways of their trailers or in lawn chairs, minus the lawns, sipping beer and regaling each other with the latest tales of hard luck.

Greg and Judy Hill have been camping in a battered trailer beneath a new bridge that crosses the Colorado River between Parachute (still called by its former name, Grand Valley, on many maps) and the new town of Battlement Mesa.

They came from Pueblo, a steel town 100 miles south of Denver, six weeks ago with their four children. This is their third season on the river, Judy Hill said.

In early May, Greg Hill was hired as a "scaler" by Daniels Construction, the prime contractor for Union Oil. He is paid $10.87 an hour to hang from a steel cable over the side of a cliff and knock down loose rocks that might endanger people working below. He puts in a 10-hour shift, with no insurance or medical benefits for the first 90 days, his wife said. Nevertheless, Greg is happy to have the work.

Every morning, Greg takes his oldest boy to his second-grade class in the little school that Parachute officials say is already obsolete. In the afternoon, Judy Hill walks to town for food and to pick up her son at school, herding the other children to the side of the road to avoid the trucks that roar by. A couple times each week they drive 16 miles downriver to DeBeque to wash clothes and shower at a laundromat.

The sheriff told them in early May that they would have to leave their bivouac by the river. Unless they find a house to rent, Judy said, "and that's just about impossible around here, I guess we'll just move down the river to another spot."

Concerned about the encampments like that of the Hill family, Garfield County commissioners called representatives of the oil companies to a meeting in Glenwood Springs earlier this month. The commissioners threatened to pull the companies' permits for construction unless something was done about illegal "squatters."

Dough Sullivan, a representative of Brown and Root Co. of Houston, prime contractor for the Colony Project, told the commissioners that his company received more than 2,500 applications in April for 83 jobs in Parachute.

"We've got people lining up at the social services office in Rifle asking for food stamps and saying Brown and Root directed them to come here," charged Commissioner Larry Velasquez, a merchant from Glenwood Springs. "Our social services budget simply cannot address a problem of this magnitude."

Sullivan accused the county officials of exaggerating the problem. "You're talking about one half of 1 percnet of the applicants who've come to us," Sullivan said. He later said that a county official told him that only 15 families from the Parchute area had applied for public assistance.

Commissioner Jim Drinkhouse of Rifle worried that "If we cite them into court for zoning violations and trespassing, we start a vicous circle. The courts are already overloaded, and if we send them to jail, it's already in bad shape, too."

Finally, the companies agreed, pending consultation with their attorneys, not to hire anyone cited by the county for violation of zoning, sanitation or trespass ordinances.

Some local officials think the problem of rapid growth in Parachute and other communities on the west slope is intractable. Ray Baldwin, Garfield County's energy impact coordinator, blamed the news media for publicizing the oil shale boom. "You can't pick up a newspaper or a magazine without seeing an article in there about oil shale," Baldwin said.