Study shows ash disposal at Iowa coal plants leads to contaminated groundwater

An analysis of groundwater monitoring near coal plants in Iowa shows elevated levels of toxic heavy metals and pollutants. 

Environmental groups say the long term effects on groundwater are another reason to stop burning coal in Iowa. 

The study, released by Iowa Environmental Council and Sierra Club, was conducted by the Interdisciplinary Environmental Clinic at Washington University and based on data collected by MidAmerican Energy Company at five coal plants it operates. 

Michael Schmidt, an attorney for the Iowa Environmental Council, said the study shows that continuing to burn coal causes expanded exposure to pollutants like mercury, arsenic, lead, and other toxic metals, which impacts public health. 

“Coal plants not only have the immediate impact from the air emissions … but long term, they also have ongoing problems for the future,” Schmidt said. “The more we keep burning, the larger these landfills get.” 

A spokesperson for MidAmerican said the Sierra Club study is “misleading” and highlights certain pieces of data to “to further its agenda.”

Coal ash regulations

The study pertains largely to the disposal of coal ash, which is a general term for the byproducts produced while burning coal, according to the U.S. Environmental Protection Agency. 

Coal ash is stored in either landfills or ponds which have ash and liquid ash residues. Coal ash can also be recycled, and according to the American Coal Ash Association, 62% of the coal ash created in 2022 was recycled into products like concrete and gypsum panels. 

According to the Sierra Club and IEC analysis, MidAmerican has contributed to nine coal ash ponds and six coal ash landfills, totaling more than 700 acres.

EPA established rules for coal ash, also called coal combustion residuals, or CCR, in 2015 after determining the improper disposal of coal ash was “linked to cases of harm to surface or ground water or to the air.” 

The 2015 rules addressed the risks of the metals and contaminants found in coal ash seeping into groundwater, blowing in the air and of “catastrophic” failures of coal surface compounds. 

Under the new rules, operators were not allowed to dispose of coal ash near certain areas like wetlands, had to establish groundwater monitoring wells and install liners into new ponds to prevent leaching into groundwater.

EPA has updated the rules several times since 2015, most recently in 2024, to include regulations, including groundwater monitoring, for inactive coal ash ponds at inactive electric plants. 

Energy companies around the country submitted a letter in January to U.S. EPA Commissioner Lee Zeldin, urging the Trump administration to “overhaul” the regulations on coal combustion residuals. 

Energy leaders in the letter said the 2024 final rule stretched beyond EPA’s statutory authority and the EPA’s  rules “result in unnecessary costs on the power sector” which will in turn impact the “affordability and reliability” of electricity. 

“Based on that letter, a number of utilities would like to avoid the costs of dealing with the pollution that has resulted from burning so much coal,” Schmidt with IEC said.

Geoff Greenwood, media relations manager with MidAmerican Energy said the company has not pushed for “rollbacks” to federal regulation around CCR. 

“To the contrary, we fully support sound policy and regulations that protect public health and the environment,” he said in a statement.

Greenwood said the industry is highly regulated, and MidAmerican is in full compliance. As regulation around CCR changed over the years, Greenwood said MidAmerican “closed, cleaned and consolidated all previously operated coal ash impoundments.” 

“Today, MidAmerican disposes of CCR material in lined, on-site landfills, in accordance with current regulations,” Greenwood said. 

Impact to groundwater 

The study looks at the Ottumwa Generating Station, the Walter Scott, Jr. Energy Center near Council Bluffs, the Louisa Generating Station near the Quad-Cities and the George Neal facilities near Sioux City, which are owned by MidAmerican. 

From the data, which is publicly available on MidAmerican’s website, the Washington University researchers found levels of arsenic, cobalt, lithium and radium elevated in ponds and landfills. 

Groundwater monitoring wells at the sites showed elevated levels of boron, chloride, lithium, sulfate, total dissolved solids, calcium and molybdenum. According to IEC, long-term exposure to these contaminants can cause heart, kidney, thyroid, gastrointestinal, neurological and other health problems. 

Monitoring from groundwater near the closed ash ponds at the Ottumwa facility showed levels of lithium that “consistently” were “6 to 7 times” the federal standard for CCR. The same monitoring also showed maximum concentrations of cobalt that exceeded the federal  standards by more than 1,000%. 

Emma Colman, a senior campaign organizer at Sierra Club, said mitigating and managing coal ash in Iowa would be “crucial” to public health. 

“If coal was a food, the FDA would have banned it years ago,” Colman said in a press release. “There is no conflicting research, no unclear science: Coal is poisonous, yet it ends up in our groundwater which means it ends up in the water we drink and the food we eat.” 

Greenwood said the Sierra Club “cherry picked” data in its analysis to “tell a misleading story.” 

“At these deactivated sites, MidAmerican monitors, and will continue to monitor, any groundwater changes in perpetuity,” Greenwood said. “While levels of minerals and chemicals in groundwater can fluctuate due to factors such as precipitation, subsurface conditions and agricultural activities, to name a few, any identified impacts exceeding allowable levels are mitigated in full compliance with federal rules.”

Greenwood also said currently operated company landfills have had “absolutely no groundwater protection level exceedances.” 

“The MidAmerican team takes very seriously our responsibility to the environment and the communities where we live, work and serve,” Greenwood said in an emailed statement. 

MidAmerican, which is owned by Berkshire Hathaway, committed to close its coal plants by 2050. In 2023, coal accounted for 23% of MidAmerican’s total energy generation.