In a small alcove at the foot of eastern Utah's Tavaputs Plateau is an old inscription left by French-Canadian mountain man Antoine Robidoux, one of the region's earliest entrepreneurs. Chiseled into cream-colored sandstone, it reads:

Passe ici le 13 Novembre, 1837
Pour Etablire Maison
Traitte a la Rv. Vert ou Wiyte

A few years earlier, Robidoux had established Fort Uncompahgre near present-day Delta, Colo., then built a second maison traitte (or "house of trade") 100 miles north in the Uintah Basin, bookending access to the abundant beaver, deer, elk and bear of the Uinta Mountains and Book Cliffs. But Robidoux's venture was short-lived. In 1844, the Utes burned both his outposts -- because he was a huckster and dealer of Indian slaves, the story goes -- and Robidoux passed into the fog of Western history.

This part of Utah, one of the most remote reaches of the Lower 48, has a long history of attempted exploitation of its natural riches. Today, companies are eyeing another potential source of wealth, this one underground. One small Canadian company believes it holds the key to developing the sizeable deposits of bitumen, or tar sands, that are splattered across the eastern and central part of the state like mud on a pickup's front fender.

More than a thousand miles north, in Alberta, over the last decade, tar-sands mining has become a major industry; Canada has overtaken Saudi Arabia as the United States' largest oil supplier. In the process, tens of thousands of acres of boreal forest have been erased by vast strip mines and iridescent tailings lakes. Meanwhile, Utah's bitumen deposits, the largest in the U.S. -- said to hold between 12 and 30 billion barrels of recoverable oil -- have remained virtually untouched.

Along the Uintah Basin's natural outcrops, such as "Asphalt Ridge," thin black jags of bitumen cut through lighter-colored sandstone. For decades, Utah's road department used the petroleum-bearing crud to pave its highways, but few oil companies considered it a viable hydrocarbon source. Then, oil prices surpassed $100 a barrel, and "energy independence" and "job creation" became twin mantras among domestic energy boosters. Calgary-based U.S. Oil Sands has now embarked on the first commercial attempt to exploit Utah's tar sands. Its PR Spring project atop the Tavaputs uses a supposedly "eco-friendly" solvent to coax oil from the state's notoriously stubborn sands.

As Canada's booming industry has shown, turning bitumen to oil requires lots of water and is highly polluting. Extracting and refining one barrel of crude from Canadian bitumen requires between two and five barrels of water. It also produces an even larger volume of toxic wastewater and as much as four times the greenhouse gas emissions of conventional oil. Utah's bitumen is interspersed with larger deposits of oil shale, an energy source that has long cast a pall over the region, because of its massive energy and water requirements. So far, no company has ever extracted it profitably; 30 years ago, for example, ExxonMobil's Colony oil shale project in western Colorado dramatically went bust, swallowing 2,000 jobs.

To make matters dicier, the bulk of Utah's fossil fuels are found on federal lands -- and the BLM is considering a move to severely restrict tar sands and oil shale development. It's reviewing a Bush-era plan to open 2.3 million acres in Utah, Colorado and Wyoming to tar sand and oil shale development, and may scale it back to slightly less than 500,000 acres.

So just how quickly and how massively might Utah's tar sands industry grow? And at what environmental cost? The U.S. Oil Sands project offers a glimpse. PR Spring could become just another scar on the land, a blip in a long history of economic and technological failure. Or it could revolutionize tar sands mining in the state -- as boosters such as Gov. Gary Herbert predict -- catalyzing Utah's unconventional oil industry and transforming this lonely region into a high-desert Alberta.

A good place to consider that possibility is atop the Tavaputs. The 200-acre PR Spring project site is nestled within a 32,000-acre lease administered through the Utah Trust Lands Administration. Several experimental unconventional oil projects are happening on nearby trust land, including a test of an oil shale extraction method headed by Red Leaf Resources. In this incubatory environment, the U.S. Oil Sands project, which got under way in 2005 when the company was still called Earth Energy Resources, has received little interference from state regulators.

U.S. Oil Sands CEO Cameron Todd says that the PR Spring project is now ready to move from experimental to commercial phase. (His confidence may partly derive from his extensive access to state officials, including Gov. Herbert, who last November led a "trade mission" to an oil conference in Calgary headed by Todd himself.) The company reportedly raised $11 million in a May stock offering, which it will use to fund expanded strip mining and processing that will generate as much as 2,000 barrels of crude oil per day.

It takes a ton-and-a-half of sand -- roughly the volume held in the scoop of a small front-end loader -- to supply raw material for just one of those 2,000 barrels. Heavy machinery would scour bitumen from the pit around the clock. Most veins lie under 20 to 25 feet of overburden, says Todd, though the deepest this company will mine are 150 feet down. The sand and mineral fines remaining after the oil has been removed will be combined, shoved back into the pit and covered with topsoil. But processing expands such wastes by as much as 30 percent. The overflow will be dumped into surrounding ravines -- a method starkly reminiscent of Appalachia's mountaintop coal mining. And the project will create miles of light pollution, illuminating one of the country's last great "dark" regions.