A federal appeals court today rejected a challenge to U.S. EPA's decision not to regulate some mercury and other hazardous air emissions from gold mining and processing operations.

The three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit found that EPA's interpretation of the Clean Air Act was "eminently reasonable."

The environmental groups that brought the challenge in Desert Citizens Against Pollution and Sierra Club v. EPA said EPA should be required to set standards for air pollutants other than mercury at gold mines and that EPA should have set standards for so-called fugitive emissions of hazardous pollutants, including mercury and hydrogen cyanide, that did not come from the mine's stacks (Greenwire, Sept. 18).

The challengers assert there are significant releases from waste rock dumps, heap leach pads and tailing impoundments.

The case centered on the Clean Air Act's "90 percent" rule, which requires EPA to ensure that nine-tenths of emissions of hazardous air pollutants are subject to standards.

On the first question, Judge Stephen Williams wrote that EPA's interpretation of the statute was reasonable and that the challengers' interpretation "would seriously risk undercutting" what Congress intended.

As for fugitive emissions, Williams wrote that although EPA's language "may be inelegant," it did state that the rule "applies only to affected sources" that were defined as "including considerably less than all activities at a gold mine."

Williams said EPA had also adequately weighed the question of whether fugitive emissions should be regulated.

Thus, "EPA reasonably concluded that the record before it provided insufficient information about the quantity of fugitive emissions or available methods of controlling them," he wrote.

There are currently just more than 20 facilities nationwide that refine gold ore with a process that removes mercury using a cyanide-containing solution, according to EPA data.

Earthjustice attorney James Pew, who represents the petitioners, said the ruling was bad news for people who live near gold mines.

"This has a very real impact on these communities out West," he said.

With the federal government failing to act, Pew called on California and other states to take action.

Click here to read the ruling.