Environmentalists have filed a legal complaint against four Illinois coal plants.
The Illinois EPA said it has also sent violation notices about contaminated groundwater to the plants owned by Midwest Generation in Joliet, Pekin, Will County and Waukegan.
Whitney Ferrell is a lawyer for the Environmental Integrity Project, which filed the complaint.
"We found pretty pervasive groundwater contamination at all four sites and are hoping that through bringing this claim we can ensure the cleanup of the groundwater in those areas and the protection of nearby communities," Ferrell said.
Ferrell said the complaint uses data from Midwest Generation to make its case.
The Illinois Environmental Protection Act requires coal plants to monitor and report on water quality near their facilities.
Midwest Generation said in a statement it is prepared to defend its operations.
"We have not been served with the complaint, but from what we have seen, it raises nothing new," Midwest Generation said in a statement on Friday. "We will be prepared to defend our operations vigorously against parties who have long sought any avenue to try to close down coal-fired power plants."
The Environmental Integrity Project and the Environmental Law & Policy Center (ELPC filed the complaint and are joined by the Prairie Rivers Network and Citizens Against Ruining the Environment.
Traci Barkley is a water resources scientist with the Prairie Rivers Network.
She said the contaminants found in the groundwater could damage aquatic ecosystems.
"That's a significant concern for us to the extent that contaminated groundwater is migrating into adjacent surface water bodies," Barkley said. "Some of the things we are most concerned about are the pollutants including selenium and mercury."
The complaint will be heard by the Illinois Pollution Control Board.