It took the Vernal office of the Bureau of Land Management seven years, millions of dollars and 584 pages to lay out a resource management plan for 1.7 million acres of public land in northeastern Utah. The document, finalized this fall, ensures that the area, which includes the spectacular Book Cliffs, will be governed primarily as a natural gas field for decades.

In late September, the Environmental Protection Agency's Rocky Mountain office sent a withering five-page critique of the plan to Selma Sierra, Utah BLM's state director. The BLM had not analyzed impacts on ozone levels from some 2,300 wells drilled in the area since 2004, Rocky Mountain EPA official Larry Svoboda wrote, nor had it predicted air impacts from the estimated 6,300 new wells approved in the plan. Vernal also hadn't bothered to include anticipated oil shale and tar sand projects.

When asked about what this means for the region's air quality, Svoboda is blunt: "We think that's a disaster waiting to happen."

After years of loosely regulated energy development under George W. Bush's Interior Department, there's a growing sense that the same kind of disaster could be in store for much of the West. The BLM has used similarly inadequate air-quality assessments to justify new resource management plans allowing vastly expanded energy development in Colorado, Wyoming and New Mexico over the next 20 years.

For a window into the West's future, look no further than Pinedale, Wyo., where energy development has contributed to unprecedented human health advisories for ozone in a place once renowned for its pristine air.

And the prospect of dangerously dirty air is only made worse, environmentalists say, by the slew of drilling projects and mineral lease sales that the BLM has approved in the waning months of the administration.

Just how nasty things will get remains to be seen. But Utah's skies appear headed for dark times. Svoboda recently sent critical missives to BLM's Price and Moab field offices. Like Vernal, both have newly minted plans authorizing major expansions of drilling on federal lands.

None of them, in Svoboda's opinion, do an adequate job of modeling possible air pollution. The BLM argues that it's impossible to model future impacts when it doesn't know how many oil and gas wells will ultimately be drilled. (Many resource management plans, including those for Price and Moab, don't estimate the extent of future development.) But EPA experts say computer models don't require that level of specificity in order to make legitimate pollution projections.

In fact, it's possible to analyze potential pollution as soon as energy leases go up for auction, something the BLM has resisted doing in other states besides Utah. The agency can estimate the number of wells because it knows where the gas is located and approximately how much is there, says Kevin Golden, an air modeler with EPA's Rocky Mountain office. And the BLM knows how much nitrous oxide and volatile organic compounds — key contributors to ozone — are emitted from drill rigs and the average well. It's even possible, says Golden, to estimate how much impact development will have 50 miles away. In general, though, the BLM analyzes projects separately, instead of assessing the collective impact of all the projects that could be allowed under a given resource management plan, Golden adds. "This is like doing an environmental analysis on the emissions from 12 cars in Los Angeles, when there are really 12 million cars."