In a May 23 letter to Selma Sierra, the Utah director of the federal Bureau of Land Management, EPA Region 8 administrator Robert Roberts said BLM's draft environmental impact study (EIS) for the West Tavaputs Plateau full-field development didn't satisfy requirements of the Clean Air Act.

The EPA is particularly concerned with a study finding that the Bill Barrett Corp. project would cause only very small increases in ground-level ozone, a conclusion EPA said "is not technically defensible."

The EPA's recommendation could slow Bill Barrett Corp.'s plan to drill 807 wells on 138,000 acres. The public land includes Nine Mile Canyon, which holds more than 10,000 known Ancient Puebloan rock-art images and ruins.

But Duane Zavadil, Bill Barrett's vice president for government and regulatory affairs, said the unprecedented action makes no sense because EPA's new ozone standards mean hundreds of counties across the nation now are out of compliance with the Clean Air Act.

"Is it appropriate to require this sort of project-specific ozone analysis?" Zavadil said. "The notion that we should go back and remodel and say the same thing is in my opinion tantamount to obstructionism and bullying by the EPA. The models aren't meant to be regulatory tools."

In the letter, the EPA acknowledges that Vernal already exceeds new federal ozone standards even without taking the West Tavaputs project into consideration. EPA's concern extends to the air-quality damage that could occur with additional oil and gas, oil shale and tar sands development proposed for the region.

The letter says the BLM has agreed to supplement the draft EIS with a further examination of ground-level ozone and other air toxics. The study would have to go to public comment and then back to EPA for analysis, the letter says.

BLM spokeswoman Lola Bird declined to comment, saying she hadn't seen the EPA letter.

Southern Utah Wilderness Alliance attorney Steve Bloch said the EPA action appears to be the first of its kind.

"This is the only instance that comes to mind in the Bush administration where the EPA has rated an energy development project in Utah as inadequate," Bloch said.

The BLM in February released the four-volume West Tavaputs draft EIS, which acknowledged the potential harm to wildlife, air quality, scenery and cultural resources. Because early public comment focused so heavily on the project's effects on archaeological treasures, the BLM offered an alternative specifically addressing industrial traffic in the canyon.

Critics of the project say it would be the death of Nine Mile Canyon, supposedly protected under the federal Antiquities Act.

With about 100 wells already developed, big rigs serving the gas fields make hundreds of trips up and down the steep, narrow dirt road. Chemicals used to suppress dust, strong enough to corrode concrete, have stuck to rock-art panels.

The fugitive dust further degrades air quality and affects water quality, riparian areas and visibility, which EPA wants BLM to study further.

If the air quality questions can't be resolved, the letter says, the project could be referred to the Council on Environmental Quality, which advises the president and vice president on how federal agencies should operate in accord with the National Environmental Policy Act.