It was 1947, and the deserts were already blooming in California when Arizona went to Washington seeking the Central Arizona Project.

It was to be the centerpiece of the state's future, an aqueduct that would bring trillions of gallons of Colorado River water across the desert to bolster a booming agricultural economy.

Four decades later, Arizona's dream has become a 190-mile-long concrete reality. The curious twist is that the $4 billion project may put most of the state's farmers out of business.

At a time when midwestern and southern states are fighting to keep their agricultural economies afloat, Arizona has decided to use its hard-won water project to support its cities, not its farms.

For now, Colorado River water flows through a concrete ditch to the cotton, wheat, barley, corn and alfalfa fields that stretch along the state's central spine. But when demand outstrips supply -- as everyone expects it will -- the spigots will be turned off first at the farm.

"The water is too costly for agriculture," said former deputy agriculture secretary John R. Norton, who left the Reagan administration this year to return to his farm operations in Arizona and California. "Urban and domestic users can pay more for it. Most farmers accept that, and they accept that in not too many years there will be no agriculture in central Arizona."

It is not, perhaps, what Congress expected in 1968 when it authorized federal funds for the CAP, the nation's most expensive western water project, under a 1902 law aimed at settling farmers in the West.

But to some economists, Arizona's decision to jettison its farms is a reflection of reality and a harbinger of the future in the arid West. Funds for new projects are drying up, and the existing water will flow, as it always has, toward money.

The statistics are devastatingly simple: Agriculture uses 90 percent of the water and yields about 2.4 percent of the state's gross revenues. The cash cows in Arizona now are the high-tech manufacturing industries that settled in the Sun Belt in the '60s and '70s, the sun-seeking retirees who flocked in at the same time and the service economy that sprang up to provide for both groups. The triumvirate of cotton, cattle and citrus that gave the state its original wealth has given way to computers, condos and Cadillacs.

The population of Maricopa County, which contains the cities of Phoenix, Mesa and Tempe as well as the state's largest concentration of farm land, is expected to hit 1.6 million by 2000, a 900 percent increase in six decades. Tucson, a town of 40,000 in 1940 and 500,000 in 1980, is expected to top 1.5 million by 2025.

Golf and tennis resorts, manicured subdivisions and landscaped industrial parks are springing up in Arizona like desert wildflowers after a summer rain, competing for land and water in the broad valleys favored by agriculture and able to pay far higher prices for both.

Given those circumstances, economists here say most Arizona farms would have been lost eventually even without the Central Arizona Project, as farmers sold out to developers. But in one of the unintended ironies that government projects frequently produce, the CAP is expected to hurry things along, and raise water prices for both farmer and city dweller in the the process.

"When they first started talking about the Central Arizona Project, they were talking about rescuing agriculture," said William Martin, an agricultural economist at the University of Arizona in Tucson. "But in this case, it's not going to rescue agriculture, and it's not going to expand agriculture. It will push agriculture out even faster."

The reason for that is economics, Arizona leads the nation in per-farmer federal subsidies -- more than $27,000 apiece in 1982, compared with second-place California's $15,700 and a national average of $3,300. but like most water decisions in the West, it has its roots in politics.

As the price for winning funds for its massive water project in the Carter administration, Arizona had to agree to bring the depletion of its underground water reserves under control.

For years, farms and cities here have drawn water from deep wells, plunged into a vast aquifer that underlies the state. The result was a precipitous drop in the water table and escalating energy costs for the pumps. In some areas, the soil cracked and sank, damaging foundations and roads.

The Carter administration wanted to avoid a repeat of its experience in California's central valley, where agricultural interests pleaded for water to replace their dwindling aquifers, then used the federal water to put new land into production and keep right on depleting the ground water.

Arizona's response was a law designed to halt overpumping of ground water within 40 years. State officials also agreed to new conditions on the use of the federally subsidized CAP water, forbidding agricultural expansion and requiring current farmers to give up ground-water pumping in an amount equal to whatever CAP water they get.

Urban dwellers, meanwhile, are legally required to conserve water, a goal that may prove difficult in a state that prides itself on its image as a desert oasis. Per capita water use in Phoenix is among the highest in the nation, and nearly half of it goes to water lawns, fill swimming pools and wash cars.

Because virtually all of Arizona's available surface water is already being captured in reservoirs, the state's decision to reduce its use of ground water means that urban growth -- and all the water-dependent amenities that go with it -- will become increasingly dependent on the CAP.

For city dwellers, that means water will get more expensive. Initially, cities were expected to pay upward of $100 an acre-foot for CAP water (an acre-foot is about 325,000 gallons, enough to flood an acre to a depth of a foot or supply a family of five for a year).

When the cities balked at the cost, federal officials agreed to a price closer to the $52 an acre-foot farmers must pay, at least in the project's early years. Even at that more generous rate, the federal water is more expensive than well water, but the real crunch is expected to come along later.

By the end of the century, according to government and private hydrologists, there will not be enough water in the Central Arizona Project to supply everyone.

In the mid-1960s, the Bureau of Reclamation was estimating that more than 17 million acre-feet of water annually rushed to sea down the Colorado River. That was the figure the courts and Congress used in divvying up the Colorado for distribution in the West and for authorizing more diversion projects that have yet to be built in the Colorado's upper reaches.

Now the bureau is estimating that the Colorado supplies only about 15 million acre-feet a year, and some private hydrologists say that even that figure is a couple of million acre-feet too high.

The upshot is that Arizona, which may get as much as 2 million acre-feet of Colorado River water through the CAP in its early years, roughly equivalent to the amount of ground water it is overdrafting, will be lucky to get half that in the future. In drought years, the aqueduct may carry practically no water, and what it does carry will go to the cities.

"In the long term, maybe in the short term, the farmers will be the ones to go," said Tucson Water Department official Frank Brooks.

It is, in fact, already happening in Tucson. In the 15 years, the city has bought more than 20,000 acres of land in nearby Avra Valley, 60 percent of the valley's farm land, and turned it back into desert. Wells and pipes are being installed to carry the underground water to Tucson.

"We propose to retire all agriculture in that basin," Brooks said. "We're not the only ones. Phoenix and Mesa are buying farm land for its water as well."

In another state, in another region, that kind of massive buyout of agricultural land might prompt some concern. But it is probably not much of an exaggeration to say that if a Farm Aid concert were held in Arizona, nobody would come.

When a group of Arizona farmers gathered in a Phoenix park recently to sell $4 box lunches for 75 cents, to dramatize the farmer's small share of food prices, the gathering drew placard-toting protesters who wanted to draw attention to crop subsidies instead.

"They told me that without farmers, my family wouldn't eat," said local activist Carolina Butler. "I said that in 30 years of cooking for my family, I have never once served cotton."

Box lunches of beef sandwiches, oranges and broccoli notwithstanding, Arizona's main crop is unquestionably cotton. More than 47 percent of the state's 1.1 million acres of farm land is planted to it. Much of the rest is in wheat and feed grains, crops for which there are federal price-support programs.

As a result, Arizona leads the nation in per-farmer federal subsidies -- more than $27,000 apiece in 1982, compared with second-place California's $15,700 and a national average of $3,300. Butler argues that the figures are misleadingly low, because water subsidies are not included and because fewer than 2,000 of Arizona's 8,300 farmers produce 97 percent of the crops.

Last year, Arizona collected nearly $100 in federal subsidies for every acre it had under cultivation, and the lion's share of the money went to growers of cotton and grain.

The figures infuriate the foes of the Central Arizona Project, who contend that the twin federal policies of cheap western water and agricultural supports have saddled them with a massive water project that the state did not need and for which they, not the farmers, will have to pay.

"You could have bought and retired all the agricultural land in Arizona at one-third the cost of the CAP," said Phoenix civil engineer Frank Welsh, who has battled the project for years under the banner of a taxpayers' group called Citizens Concerned About the Project. "Then, all of a sudden, the project became an urban-industrial project."

Welsh likes to cite engineering studies to prove his point. Among his favorites is one done for the state Department of Water Resources. The report found that Arizona, minus agriculture, has enough water without the CAP to support more than 10 million people, nearly five times its current population.

The farmers, meanwhile, are already moving out. John Norton has lost the land he farmed near Phoenix to urbanization. He said he intends to give up this year the 4,000 acres of leased land on which he grew cotton south of Phoenix in Pinal County.

The immediate impetus for his move is depressed farm prices, rather than water shortages, but Norton said he expected more Arizona farmers to follow suit.

"They feel they'll be compensated," he said. "A lot of them are profiteering on the land boom and couldn't care less . . . . Nobody's making money in farming. What do you care if they put you out of business if they hand you a sack of gold to do it?"