A congressional committee is charging that the Environmental Protection Agency violated the Clean Air Act when it approved an expansion of a coal-fired power plant in Uintah County without imposing controls for carbon-dioxide emissions.

A letter Wednesday from the House Committee on Oversight and Government Reform said the committee is investigating how the EPA made its decision. The letter also states that the committee is interested in finding out whether the agency's decision involved communications from the White House.

The EPA approved the new 110-megawatt, coal-burning power unit for the Bonanza Power Plant on Aug. 30. The unit would be built about 35 miles southeast of Vernal at the site of the present plant, owned by South Jordan-based Deseret Power Electric Cooperatives.

Tim Wagner of the Utah Chapter of the Sierra Club criticized the EPA shortly after the permit was issued, saying the agency acted contrary to a recent Supreme Court ruling that it must regulate carbon-dioxide emissions. The EPA should not have acted on the Bonanza plant until the agency had formulated regulations for carbon-dioxide emissions, he said.

"This letter makes it very clear that the EPA is absolutely neglecting its responsibilities as put down by the U.S. Supreme Court," Wagner said Wednesday.

But an EPA spokeswoman, Jessica Emond, told the Deseret Morning News earlier this month that while the EPA has the authority to address mobile sources of carbon dioxide such as cars, it lacks the authority to regulate the gases from stationary ones such as power plants.

The House Committee on Oversight and Government Reform criticized the EPA decision Wednesday in the letter to EPA administrator Stephen L. Johnson.

"Two weeks ago, in issuing a permit for a new coal-fired power plant, the Environmental Protection Agency took its first regulatory action directly related to global warming since the Supreme Court ruled in Massachusetts vs. EPA that the agency has authority to regulate greenhouse gases," wrote Rep. Henry A. Waxman, D-Calif., the committee's chairman.

"Remarkably, EPA refused to consider the global-warming effects of the plant or to require any measures to mitigate that harm, contravening a Clean Air Act mandate and ignoring EPA's ample discretionary authority to act."

The letter urges the EPA to reconsider its position "in this and future permit decisions."

The agency's decision regarding the Utah plant and any future decisions following that precedent could affect investment of "tens of billions of dollars in a new generation of highly polluting power plants that will drive substantial additional global warming, without mitigating those effects," Waxman added.