Conservation groups have filed an appeal challenging an agreement between the state and PPL Montana that requires the company to more closely monitor wastewater leaking from the company’s Colstrip power plant.

The Aug. 3 agreement between PPL and the Department of Environmental Quality set new guidelines to investigate and clean up the seeping wastewater. However, no fines were levied, and the agreement contains few deadlines for action.

The attorney for the conservation groups, Jenny Harbine, said the agreement would allow decades of groundwater pollution to continue at the eastern Montana plant.

“There’s no guarantee that PPL is required to take action to actually clean up existing contamination,” Harbine said. “DEQ has acknowledged the coal ash sludge ponds have been leaking since they were constructed more than 30 years ago — and all the while they were poisoning the groundwater.”

Harbine’s clients — the Sierra Club, National Wildlife Federation and Montana Environmental Information Center — filed an appeal Wednesday asking the state Board of Environmental Review to reject the agreement. DEQ director Richard Opper, who signed the agreement, could not be reached for comment.

The contamination dates to the 1980s at Colstrip, the second-largest coal-fired plant west of the Mississippi.

In 2008, PPL and four companies that co-own the plant paid $25 million to Colstrip residents whose water was fouled by leaking

ash ponds.

The plant’s prior operator, Montana Power Co., kept the problems hidden for years before notifying the community. By then, water tainted with boron had caused stomach ailments, although no serious illnesses were reported.

PPL took over the 2,100-megawatt plant in 1999 and operates it on behalf of its owners

Since coming on the scene, the company has upgraded the material used to line the coal ash ponds and installed two plants that dry out coal ash waste from the power generator, reducing the amount of water involved and cutting down on potential seepage from the storage ponds, said spokesman David Hoffman.

The agreement with the DEQ, known as an administrative order on consent, will continue steps the company already was taking to deal with the wastewater problem, he said. Hoffman acknowledged that seepage continues from the plant but added that the process laid out in the agreement calls for continued monitoring and the cleanup of any contamination that is detected in Colstrip-area groundwater.

“It formalizes the process we are already involved in with the DEQ,” Hoffman said. “It really provides a comprehensive process to set clear responsibilities and duties to address seepage from some ponds that may occur.”

A separate lawsuit from the conservation groups, seeking to force the DEQ to take action on the ash ponds, is expected to be filed in state District Court in coming weeks, Harbine said. The second legal action is needed because the Aug. 3 agreement appears to limit the agency’s enforcement powers, she said.