ST. CHARLES COUNTY, Mo. — Regional electric utility Ameren is discharging toxic coal ash pollutants into the Mississippi River at the utility's coal-fired Sioux Energy Center — not far upstream from where St. Louis draws its municipal drinking water — in violation of the Clean Water Act, according to a complaint sent to the company, plus federal and state authorities.
Great Rivers Environmental Law Center detailed the allegations in a 19-page "notice of intent to sue" sent to Ameren last month. Great Rivers is representing two affiliated water-quality nonprofits, Missouri Confluence Waterkeeper and Waterkeeper Alliance.
The complaints are merely the latest in a long saga of criticism surrounding Ameren's disposal of coal ash, a byproduct from burning coal that contains a range of harmful components, including arsenic and mercury.
The company's four coal-fired power plants in the St. Louis area all sit alongside major rivers and, together, have 14 total coal ash ponds — some lined underneath, and others unlined — where material sits buried into the water table at various depths.
Sioux, near West Alton in St. Charles County, sits along a chute of the Mississippi River, just upstream of its confluence with the Missouri River. The letter argues that Ameren's own data demonstrate that pollutants from the plant's coal ash are in nearby groundwater and surface waters of the chute. The document also says pollutants are being discharged to groundwater in quantities that exceed the Environmental Protection Agency's Health Advisory level and "may create human health risks."
The letter, sent on Feb. 12, was also given to regulators at the EPA and the Missouri Department of Natural Resources, according to Great Rivers. The firm said if Ameren does not address the complaints within 60 days of receipt of the letter, a lawsuit could then proceed — a step the groups say they intend to take.
Bob Menees, a lawyer for Great Rivers, said he believes the same issues apply to all of the company's unlined ash ponds but building a case to demonstrate the alleged violations was easiest and most feasible at Sioux.
Ameren defended its coal ash disposal practices, saying years of testing have found no impact to public drinking water or private wells.
"Extensive sampling of the Mississippi and Missouri rivers found there is no difference in the water upstream and downstream of the Sioux Energy Center or any one of Ameren Missouri's generating facilities," Craig Giesmann, the company's senior manager of environmental services, said in a statement.
Ameren's coal ash ponds have been leaking for years. The company is now converting to dry ash storage at its coal plants, but the pond controversy continues. In 2019, for instance, the utility announced a decision to cover its ash ponds while leaving the material buried in the ground, despite outside concerns about impacts to water quality. Critics accused Ameren of exaggerating the costs of removing the material and pointed out that other utilities have dug up and removed coal ash.
Ameren's disposal practices are all the more problematic, critics say, given the location of coal ash ponds in the floodplains of the Mississippi and Missouri rivers. Flood waters have at times overtopped the ash ponds.
Menees said that while disposal of coal ash in increasingly flood-prone areas may not be "wise" policy, that matter is not necessarily the focus of the potential litigation.
"Maybe the catastrophic thing is going to happen," he said, alluding to flood risks. "But what is happening for sure is they're polluting the Mississippi River."
