A group of environmental activists is looking to intervene in a lawsuit against Westar Energy Inc., in hopes the state’s largest electric utility will be held to the strictest of standards.

The lawsuit — filed in February by the U.S. Department of Justice and the Environmental Protection Agency — claims Westar is violating federal air-quality laws at its Jeffrey Energy Center, a coal-fired power plant located near St. Marys.

A motion by Sierra Club environmental advocates asks that a broader look be considered when determining whether the plant meets environmental standards, an attorney for the club said at a Tuesday morning news conference in Lawrence’s Riverfront Park. The group used the smoke rising from Lawrence Energy Center as a backdrop for its news conference, but the coal-fired power plant north of Lawrence is not named in the lawsuit.

“We believe that it’s essential that Westar come into compliance” with the Clean Air Act, said Bob Eye, a Sierra Club attorney, as anti-coal supporters stood behind him with signs. “It is the law of the land and the failure to do so diminishes not only the integrity of the act but has (an) impact on the health of the public and our environmental quality.”

The original lawsuit filed in February claims Westar made modifications to the center northwest of Topeka but didn’t do enough to update the plant’s pollution control equipment. The lawsuit claims the equipment is out of date and asks the court to force Topeka-based Westar to install new equipment and potentially pay millions of dollars in fines.

Without upgrades, the feds claim the plant may produce higher levels of such pollutants as sulfur dioxide, nitrogen oxide and particulate matter, which can contribute to smog and acid rain.

But the Sierra Club said the lawsuit is limited in what pollution types are being considered under the federal Clean Air Act and asks that other, finer pollutants and carbon dioxide emissions be scrutinized.

Craig Volland, chairman of the Kansas air quality committee for the Sierra Club, said the group wanted to make sure the finest particles are also regulated.

“We fully expect that our involvement will actually improve the environment in a measurable way,” said Volland, who is also a technical adviser for the group.

Westar has said it believed modifications to the plant complied with federal environmental law when plant modifications were made 10 to 15 years ago.

The company says it has spent $460 million upgrading Jeffrey to reduce emissions and that it plans to invest millions more in coming years.

“We’re not doing this because of their allegations,” said Westar spokesman Nick Bundy. “We’re doing these things now because they need to be done, because we want to be good environmental stewards.”

The Sierra Club announced its anticipated involvement in the anti-coal lawsuit as part of a national campaign against coal-fired power plants, which federal figures show generated 68 percent of the state’s electricity in June.

A federal judge will determine whether the environmental group can intervene in the lawsuit.