PEORIA — After seven years, a coalition of local environmental groups has won its legal battle against the company that owns the Powerton electrical plant in Pekin.

Now, all that remains is for a hearing officer with the Illinois Pollution Control Board to determine how Midwest Generation — which has since been taken over by NRG Energy — should be punished for its actions in Tazewell County and at three other plants located in Waukegan, Joliet and Will County.

Specially, the board found in their June 20 decision:

Midwest Generation caused or allowed discharge of coal ash constituents into groundwater at all four power plants. there was an elevated level of arsenic, boron and sulfates at the facilities, exceeding what is allowed by the state. the company violated state regulations at its Powerton Station by depositing coal ash cinders directly upon the land, thereby creating a water pollution hazard. The board also found the company did not take measures to remove (the coal ash) or prevent it leaking of contaminants into the groundwater.

“There is a moral obligation to ensure that polluters are held accountable for the impact they have on the groundwater of Illinois communities,” said Faith Bugel, a Sierra Club attorney. “The Board’s decision calls NRG out, and we urge the Board to impose a remedy that holds out-of-state companies accountable for cleaning up the pollution they dump in Illinois.”

In response, David Knox, a spokesperson for NRG Energy, said in a statement to Energy News Network that the company will determine its next steps.

“Midwest Generation, which was acquired by NRG in 2014, has worked cooperatively with the IEPA over many years to continually take steps to protect the environment, including entering into compliance commitment agreements and implementing groundwater management zones,” the statement read. “The issues raised in this proceeding are complex, the circumstances at each site vary and involve historic activities that occurred under the prior utility ownership of the plants.”

In 2012, the Sierra Club, the Environmental Integrity Project, the Environmental Law and Policy Center, Prairie Rivers Network and Citizens Against Ruining the Environment all filed complaints with the state, alleging groundwater contamination and open dumping in violation of the Environmental Protection Act and against state regulations.

The complaints contain records of multiple alleged violations of Illinois pollution laws. The data, according to the complaints, comes from Midwest Generation’s own monitoring reports. Reports have shown excessive levels of arsenic, boron, chloride, iron, lead, manganese, mercury, nitrate, selenium, sulfate, thallium and total dissolved solids since monitoring began in 2010. Coal ash is mixed with water and placed in disposal ponds at Powerton, according to the complaint.

Andy Kravetz can be reached at 686-3283 or akravetz@pjstar.com. Follow him on Twitter @andykravetz.