The three smokestacks of Waukegan Generating Station are visible from a nearby beach, where a passerby prepares to surf in Lake Michigan.
The three smokestacks of Waukegan Generating Station are visible from a nearby beach, where a passerby prepares to surf in Lake Michigan. Credit: Sarah Aie

This story is part of a 12-part investigation by the Chicago Investigative Project in the graduate program at the Medill School at Northwestern University.

In more than 700 spots nationwide, toxic coal ash is stored in ponds, dammed impoundments, landfills, and more unusual structures: a meteor crater, old limestone quarries, and the “Ash Island” rising in a lake popular with Tennessee boaters and swimmers. 

The vast majority of these coal ash repositories are contaminating groundwater with dangerous pollutants, according to monitoring data reported by companies and compiled by environmental groups. 

Since federal coal ash rules took effect in 2015, many companies have seemingly flaunted provisions against storing coal ash in contact with groundwater, in flood zones, or other risky areas.

In January the Environmental Protection Agency announced its intention to actually enforce the coal ash rules. But a months-long investigation by the Medill School of Journalism at Northwestern University reveals the enormity of the challenge.

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The EPA is largely reliant on state regulators and community groups for enforcement and vigilance. But state agencies thus far have largely approved companies’ coal ash management plans with seemingly little scrutiny. And even when state and federal regulators and companies work together to protect human health and the environment, there is no easy way to deal with nearly a billion tons of coal ash dumped over the last century, not to mention the more than 100 million tons of coal ash still being created each year.

In June, E&E News published a leaked list of 160 sites where the EPA is investigating closure plans for unlined pits that could leave ash contaminating groundwater. 

“I’ve seen firsthand how coal ash contamination can hurt people and communities. Coal ash surface impoundments and landfills must operate and close in a manner that protects public health and the environment,” EPA Administrator Michael Regan said in a statement in January. “For too long, communities already disproportionately impacted by high levels of pollution have been burdened by improper coal ash disposal.”

Water at risk

Coal ash is almost always dumped near water bodies — rivers, lakes, and reservoirs — since it’s historically been held on the sites of coal plants that need water for cooling. Coal ash contaminants can easily leach into groundwater, polluting aquifers that serve municipal water systems and private wells. It can also flood or seep into water bodies.  

Companies are planning to close the great majority of coal ash impoundments in place, despite the fact that most of them are unlined, allowing the potential for ongoing groundwater contamination. In January, the EPA turned down requests from eight companies seeking an extension on an April 2021 deadline to stop putting coal ash in unlined impoundments. The denials mean those companies — like many others — need to start closing their coal ash pits, but how they close remains to be seen. Some of the EPA’s extension denials said companies did not adequately consider removing coal ash from pits and moving it to safer locations, but those decisions don’t prohibit the companies from closing ash ponds in place.

Coal ash 101: Everything you need to know about this toxic waste

As coal plants close nationwide, they leave behind nearly a billion tons of toxic coal ash. The Medill School of Journalism spent months investigating the coal ash threat and how regulators, companies, and environmental groups are handling it. 

Here are the basics that will help you understand this looming threat.

What is coal ash?

Coal ash is the toxic byproduct of burning coal to generate electricity. It contains heavy metals that can contaminate groundwater, lakes, and rivers. 

Where is coal ash located?

Coal ash is stored in more than 700 ponds and landfills nationwide, most of them unlined. Ash can also be recycled — known as “beneficial reuse” — in which it is used to make concrete or build roads. 

What is the Coal Combustion Residuals (CCR) Rule?

In 2015, the EPA established rules for coal ash units, requiring companies to test groundwater, remediate contamination, and make plans to close the units. Companies have to post groundwater monitoring data and closure plans online.

The rule excludes hundreds of “legacy ash ponds” that closed before the federal rule took effect in 2015, yet these ponds are still causing serious groundwater contamination. The rule also does not cover coal ash that was over decades dumped and scattered around coal plant sites and even surrounding areas, often used to build up berms or fill in land.

Is coal ash contaminating our water?

Data posted by companies shows that contaminants around coal ash ponds frequently exceed limits set by the EPA, sometimes exponentially. Private wells used for drinking water can be and have been contaminated by coal ash. Rivers and lakes used for recreation and municipal water supplies can also be contaminated by coal ash.

What’s in coal ash?

Boron is linked to reproductive problems like low birth weight and is also toxic to aquatic life.


Lead is a potent neurotoxin linked to swelling of the brain and nervous system damage.


Lithium is linked to liver and kidney damage as well as neurological diseases and birth defects.


Arsenic is linked to nervous system damage and higher rates of cancer. 


Molybdenum is linked to gout, high blood pressure, and liver diseases. 


Cobalt is linked to thyroid damage and blood diseases.

How is a coal ash pond closed?

Coal ash sites need to close after getting their final shipment of coal ash, if they are polluting groundwater above certain standards, or if they fail to meet other safety criteria. The rules say all unlined ponds needed to stop accepting waste by April 2021, though some requested exceptions and have continued filling with coal ash. 

Cap-in-place closure

A protective cover is placed over the coal ash so rainwater doesn’t get in and cause flooding or increased leaching into groundwater.  If the coal ash is left in contact with groundwater or permeable rock, it can continue leaching contaminants even when capped.

Removal closure

Coal ash is excavated from a pond, dried, and moved to a lined landfill above the water table. Companies may be able to build a landfill on the power plant site. Shipping coal ash to landfills off-site means heavy truck traffic or shipping by barge or rail.

Who pays for coal ash cleanup? 

The owners of coal ash sites — utilities or power companies and their shareholders — can pay the cost of coal ash cleanup, often hundreds of millions or even billions of dollars across multiple sites. 


Utilities can seek approval from state public service commissions to bill the cost of coal ash cleanup to ratepayers. They can even seek a profit as a portion of the costs. 


If coal ash is designated a Superfund site, the EPA can make the responsible parties — utility or power companies — pay for the cleanup. The government can also pay for the cleanup from a pool of Superfund money, especially if the companies no longer exist or can’t pay. 

Compiled by Sruthi Gopalakrishnan.

The EPA recently released a list of more than 300 coal ash units “potentially with waste below the water table.” The federal rules prohibit closing a coal ash impoundment with ash within 5 feet of groundwater, but many sites have proposed to do just that — including Greenidge Generation, a Bitcoin-mining operation in the Finger Lakes; Lincoln Stone Quarry near Joliet, Illinois; Clifty Creek in Southern Indiana; and multiple Tennessee Valley Authority and Georgia Power sites.

“We’ve seen substantial noncompliance” with the federal rules, said Earthjustice attorney Lisa Evans. “We haven’t yet seen EPA or a state agency bring an enforcement action to stop these illegal closures. In fact we’ve seen the opposite — we’ve seen Georgia and Alabama giving utilities permits to close a [coal ash] unit with ash in contact with groundwater, which is a violation of the federal rule.” 

A Medill analysis of U.S. Geological Survey data showed high concentrations of private wells around unlined coal ash impoundments, particularly in the rural South and Midwest. Municipal water systems also draw water from aquifers near coal ash, as seen in USGS data, including in multiple sites in Missouri, Illinois and Wisconsin.

There is typically no government oversight of private wells, hence it is usually up to citizens to pay to test their own water, except in cases where specific concerns have spurred local governments or utilities to test wells. 

When environmental groups or local governments have done spot testing of wells because of coal ash concerns, contamination has been found — for example, near Lincoln Stone Quarry; the Possum Point power plant in Prince William County, Virginia; and the Michigan City power plant in Northwest Indiana. A report by Earthjustice found evidence of well contamination linked to coal ash at 24 sites, including in Wisconsin, North Carolina, Pennsylvania, and Illinois. Since countless people living near coal ash never test their wells or understand possible risks, much contamination could be going unseen.

Meanwhile, a number of sites risk spilling coal ash into nearby rivers and lakes through erosion or impoundment failure. That’s what happened when an impoundment near the Tennessee Valley Authority’s Kingston plant collapsed just before Christmas in 2008, inundating rivers and homes with more than a billion gallons of coal ash. The disaster, which caused multiple deaths, sparked the coal ash regulation process.

More than 200 coal ash enclosures nationwide are designated as significant or high hazard, according to company data, meaning impoundment failure would likely cause human death or significant environmental and economic damage. More than 30 impoundments with a high hazard rating — meaning possible fatalities in case of failure — are slated to close in place. Companies generally report their impoundments meet structural safety criteria during regular inspections, according to Medill’s analysis, and environmental experts say companies and regulators have been more vigilant regarding structural safety since the Kingston disaster. Still, the continued existence of high- and significant-risk impoundments — including many along the Ohio River — raises concerns.

“At a number of places, these berms and the dikes themselves are actually built on top of or out of coal ash,” noted Earthjustice attorney Jenny Cassel. “And that ash easily destabilizes.” Under enough pressure and water, dikes made of coal ash can go through “liquefaction,” Cassel noted: “It sort of turns into water and doesn’t hold anymore.”

Flooding can also carry coal ash across land and into water bodies; 172 coal ash units are located in 100-year flood zones or regulatory floodways, according to companies’ data. The majority of them are slated to close in place. Floods and heavy rains are only expected to increase with climate change, with 100-year floods already happening more frequently.

“One of the worst waste disposal scenarios you can imagine is to leave [coal ash] in the floodplain in contact with groundwater,” said Indra Frank, health and water policy director for the Hoosier Environmental Council. “And that’s what Indiana has right now; we’ve got a lot of that.” 

Thom Cmar, an Ohio-based attorney for Earthjustice, noted that flooding not only can spread ash outside ponds, but also increases groundwater contamination.

“People tend to focus a lot on the possibility for the sort of worst-case scenario of disaster, but the bigger problem is what’s happening, not necessarily on a day-to-day basis, but every time there’s a major rainstorm,” Cmar said. “The river levels rise so that ashes can be saturated with water. And that creates a steady, ongoing source of pollution that will have an effect on the river that runs right next to it and the groundwater beneath it for decades into the future.” 

Ash has even been allowed to remain in areas plagued by sinkholes, like the Tennessee Valley Authority site near Muscle Shoals, Alabama, where sinkholes in the past caused coal ash to drain rapidly out of ponds multiple times. At Georgia Power’s Plant Bowen, the company is planning to add a liner to a coal ash pond but leave it in the same spot where in 2002 a four-acre sinkhole opened and released coal ash into a nearby creek.

Solutions and more problems

Environmental experts generally argue that the best way to deal with coal ash is to excavate it from ponds, dry it, and store it in a lined landfill.

“When ash is in groundwater near waterways, excavation is the only way to eliminate the source of pollution and store the ash safely for the long run,” said Frank Holleman, senior attorney with the Southern Environmental Law Center, which has filed lawsuits forcing companies to remove ash from ponds. “If you put ash in the ground next to a water body, which is where these places are, it’s going to be in contact with groundwater. If ash is sitting in groundwater near a river or lake, it’s inherently a dangerous situation.” 

In South Carolina, North Carolina, and Virginia, state laws and legal settlements mean that nearly all coal ash must be excavated from unlined or improperly lined impoundments and put in modern lined landfills. The utilities Duke Energy, Dominion Energy, and Santee Cooper will have to remove ash from more than 30 units spread over at least 17 plant sites, based on analyses of company data. Duke is slated to excavate more than 120 million tons of coal ash in North Carolina and South Carolina by 2035. About 35 million tons have already been excavated in those states, according to Duke.

Advocates say this shows full removal of coal ash is possible, and companies that have said they can’t remove ash should try harder. 

“Now that they’ve created this problem, they’re saying it will be too hard for us to clean up the mess we made,” Holleman said. Duke’s excavation “disproves that argument.”

But even this best-practice solution raises problems. Coal ash is often moved to existing landfills many miles away, often across state lines. This means transporting it by rail, barge, or truck — which comes with its own environmental and health impacts. Companies seem to most often propose moving coal ash by trucks, predicting it will take years for hundreds of trucks a day to clear an impoundment. As coal plants are disproportionately located in lower-income and minority areas, this means these communities suffer from diesel emissions and dangerous traffic.

Landfills likewise are disproportionately located in low-income and minority areas, where residents are angry their communities have become the final resting place for coal ash. For example, when the Tennessee Valley Authority decided where to move ash from its massive Allen Fossil Plant in Memphis, it considered seven landfills that were nearly all in minority areas. It ultimately decided to truck the ash to a nearby landfill in a majority Black neighborhood of Memphis, despite residents’ strident opposition. After TVA’s 2008 disaster, the ash from the cleanup was trucked from the predominantly White city of Kingston to a landfill in Uniontown, an impoverished Black community in Alabama.

Coal ash “was brought in against our will,” said Uniontown resident Carlene James. “By the time the people knew about it, it was a done deal.” 

Coal ash from the massive AES power plant in Puerto Rico has likewise created problems when the company acquiesced to local demands to move it. 

When AES dumped the ash in the Dominican Republic, residents reported spikes in cancer and birth defects, and the Dominican government banned its import. Now AES’ coal ash is being sent by barge to a private port in Jacksonville, Florida, then trucked to a landfill in Georgia, despite the outrage of local officials. Last year a barge carrying coal ash from Puerto Rico to Jacksonville ran aground on a sandbar and spilled its cargo into the ocean, a harbinger of the environmental and economic risks of such transport, as local leaders see it. 

Experts often argue that companies should build a new landfill on their power plant site to avoid transporting coal ash. But even this solution can raise concerns, as in Possum Point, Virginia, where Dominion’s plan to store coal ash in a new on-site landfill has infuriated neighbors who say they’ve dealt with the coal plant’s pollution for too long. Possum Point shows that wealthier residents can also see the impacts of coal ash — the landfill will be right near a new development of homes costing up to $1 million.

Another challenge of more rigorous coal ash cleanups: Ratepayers often pick up the tab. In most states, electric utilities are able to bill ratepayers for the investments they make in power generation and environmental remediation, while earning an extra profit in the process. State utility regulators around the country have been debating how much utilities can charge ratepayers for coal ash cleanup, and how much profit they can bake into the equation.

South Carolina regulators decided and the state Supreme Court agreed last year that Duke couldn’t bill South Carolina customers for cleaning up coal ash in North Carolina. In North Carolina, state regulators also last year negotiated with Duke to ultimately reduce the coal ash tab it planned to place on ratepayers by $1.1 billion.

But more often companies are able to recoup their costs plus a profit, and the costs to individual households can be significant. In Georgia, ratepayers are expected to pay for Georgia Power’s coal ash cleanup estimated at $9 billion — around $4,000 per household over 60 years.

Georgia Power had previously planned to close the majority of its ponds in place, according to environmental groups’ analysis of company plans submitted under the federal rules. But the EPA has indicated it may require more rigorous cleanup including more coal ash removal, which could better protect water but cause costs to climb. Georgia Power spokesman John Kraft said that currently, the company is in the process of removing ash from 20 ponds while closing nine in place. 

Legacy ash loophole 

The federal rules don’t currently cover coal ash impoundments that stopped accepting ash before 2015. In a notice of intent to sue sent to the EPA and Department of Justice in May, national environmental groups and community organizations in Illinois, Indiana, and Tennessee said they’ve identified at least 140 coal ash impoundments not covered by the rules, which they say are even more likely than the regulated impoundments to be contaminating groundwater.

In 2018 — in response to a citizen lawsuit — a federal appeals court ordered the EPA to add such legacy coal ash impoundments to the federal rules. In its ruling, the court likened the EPA’s decision not to regulate legacy ash ponds to a kindergarten teacher only requiring students to clean up a drink they had just spilled while allowing a drink spilt in the past to remain on the floor. “A student who refused to clean up that completed spill (as Industry Petitioners would have it) might well find himself on time out,” the opinion said. 

While environmental groups cheered the decision, Earthjustice and other groups allege in their recent filing that almost four years later, seemingly little progress has been made on regulating legacy ash. 

In addition to legacy ash ponds not yet covered by the 2015 rules, “scattered, historic” ash also poses a major problem, environmental groups say. 

In decades past, coal ash was distributed liberally across coal plant sites and nearby areas, often used as structural fill to build up land or create berms. Such historic ash presents a particular challenge, as there are few records about where exactly it was deposited. Environmental groups have pieced together details through historic photos and documents.

“Before there were any regulations whatsoever for this stuff, they just kind of dumped it anywhere,” Cassel said. “Near the coal plants, particularly next to the rivers, they would just find depressions in the ground or dig them and throw coal ash in.” 

At NIPSCO’s Michigan City power plant, for example, advocates are demanding that the utility address coal ash that was mixed with sand and soil in land butting up against Lake Michigan, held back only by corroding steel walls. The company has said the coal ash is in low enough concentrations that it does not pose a risk, but Hoosier Environmental Council attorney Indra Frank disagrees. 

“They needed to dispose of coal ash for several decades and they had this area that they had walled off, that they were busy filling in,” she said. “That was by far the least expensive disposal method they had.”

At We Energies’ Oak Creek plant in Wisconsin, historic coal ash cascaded into Lake Michigan when a bluff collapsed in 2011. The coal ash had decades ago been used to fill a ravine.

Coal ash not covered by the federal rules can also impede cleanups that are covered by the rules, if it influences the way groundwater monitoring results are interpreted. Under the rules, companies are required to install “upgradient” and “downgradient” monitoring wells. Contamination in wells downgradient of coal ash ponds covered by the rules is compared to the upgradient wells. If contamination is as high or higher in upgradient wells, it’s generally assumed that contamination did not come from the coal ash ponds but from other sources. However historic ash on the site can pollute upgradient wells, essentially letting companies off the hook since they can argue contamination is from a source other than the coal ash ponds covered by the rules.

At the Clifty Creek plant on the Ohio River, for example, Indiana-Kentucky Electric Corporation filings acknowledge that contamination likely comes from historic coal ash dumped since the plant opened in the 1950s. But the corporation doesn’t plan to remediate contamination since it is not from ponds covered by the rules. A similar situation has played out at the Four Corners coal plant on the Navajo Nation, according to the environmental groups’ notice of intent to sue.

Silver linings

Coal plants are closing at a rapid clip nationwide, as coal-fired power becomes increasingly more expensive than power from renewables and natural gas (excepting the natural gas price spike driven by the Ukraine war). That means job and tax base losses for communities home to those plants. But rigorous cleanup of coal ash can provide jobs to help ease the transition away from coal, advocates point out. 

In Colstrip, Montana, where a large plant near the Northern Cheyenne reservation is likely to close in coming years, robust coal ash cleanup could create about 400 jobs annually for a decade, according to an analysis by the Northern Plains Resource Council. The nearby Northern Cheyenne tribe, where unemployment is high, could benefit from those jobs, though many tribal members remain suspicious of what they call the coal company’s history of broken promises. 

The pollution burden of coal ash can also be lessened by increased recycling, or “beneficial use.” Coal ash is a crucial ingredient in making concrete and it is also used in building roads and other structures, while the coal-burning byproduct gypsum is used in drywall. When done correctly, such use is safe, according to industry and advocates alike. Environmental advocates and state regulators often call for increased recycling of coal ash, to reduce the amount that must be stored and meet market demands.

Even as the U.S. deals with countless tons of unwanted coal ash, certain types of coal ash are being imported from abroad to serve industry. With more investment and careful handling, more coal ash could be reused and coal ash currently stored in landfills or impoundments could be funneled into reuse, experts note. Coal and construction industry sources lobbied hard during the rule-making to ensure coal ash was not designated a hazardous waste, which would have impeded reuse.

“They wanted coal ash to be listed as non-hazardous material, so they could use it for recycling. … And yet, why aren’t we doing it more often?” asked Dean Naujoks, the Potomac Riverkeeper representing the Riverkeeper organization in Virginia and surrounding areas. 

Attorneys and advocates who have led the fight for better regulation and enforcement say they are hopeful that the EPA’s recent emphasis on coal ash rules will lead to real change.

“As we move on from coal and transition to clean energy,” said Earthjustice attorney Lisa Evans, “we’ve got to make sure that these sites are left clean and healthy for the communities that have been burdened with this pollution for so many decades already.”

Additional reporting by Gina Castro, Kelsey Turner, Peter Winslow, Felix Beilin, Sruthi Gopalakrishnan and Chloe Hilles.

Editor’s note: This story has been updated to add a clarification from Georgia Power.

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Kari has written for the Energy News Network since January 2011. She is an author and journalist who worked for the Washington Post's Midwest bureau from 1997 through 2009. Her work has also appeared in the New York Times, Chicago News Cooperative, Chicago Reader and other publications. Based in Chicago, Kari covers Illinois, Wisconsin and Indiana as well as environmental justice topics.

Josh Irvine graduated from Northwestern University with a degree in journalism in 2022. He currently reports on poverty for the Telegraph Herald of Dubuque, Iowa, as a Report for America corps member.

Diana Leane graduated from Northwestern University with a master's degree in journalism with a focus in investigative reporting in June. She received a bachelor's degree in journalism from Boston University. She's interned at the Daily Herald and worked for BU's student newspaper, The Daily Free Press. When not reporting, she enjoys gardening and baking.

Tom Quinn graduated from Northwestern with a bachelor's degree in journalism. He spent much of his college sailing career on Lake Michigan as a skipper for the Northwestern Sailing Team. He is now in New York City exploring a passion for law and listening to podcasts while walking along the Hudson River.

Mrinali Dhembla is a freelance journalist based in Chicago/New Delhi. She graduated with a master of science in journalism from Northwestern University’s Medill School of Journalism in 2022. She has previously written for various publications such as The Slate, Chicago Reader, and Block Club Chicago, among many others.

Hayley Starshak graduated from Northwestern University with a master’s degree in journalism, specializing in investigative reporting. She went to undergrad at the University of Denver, majoring in strategic communications and Spanish. She has a passion for storytelling, local news, and defending the Oxford comma.

Sarah Aie is an undergraduate student studying journalism and environmental policy and culture. She’s been the video editor at The Daily Northwestern and has previously written for the city and campus desks. She is currently interning at Circle of Blue, focusing on multimedia production. Outside of the newsroom, she enjoys reading about and watching all things film and TV.