Accidents Waiting to Happen: Coal Ash

Hundreds of coal ash pits and ponds sit near the banks of American waterways, threatening toxic spills that can cause long-term damage to the environment and public health.

Millions of tons of toxic coal ash are stored at U.S. coal plants

When coal is burned at any of America’s more than 200 coal-fired power plants, it leaves behind waste called coal combustion residuals, commonly referred to as ash. In 2022, over 75 million tons of these residuals were produced nationwide.

Coal ash is often mixed with water and stored on-site at power plants; in other cases, coal ash is stored in on-site landfills. There are approximately 700 of these coal ash pits and landfills located in 43 states across the U.S.

Coal ash has long been known to be highly toxic and dangerous to humans and wildlife, and science continues to uncover new hazards. A recent EPA draft risk assessment published in 2023 identified greater health risks from radioactivity and arsenic in coal ash than had been previously estimated.

Coal ash puts our waterways at risk

Coal-fired power plants need access to water for cooling, and as a result many coal ash pits are located on a water body’s edge, sometimes separated by just a narrow embankment. A total of 172 coal ash pits and landfills in the U.S. are located in 100-year flood zones or areas designated to receive flood waters (“floodways”).

During floods or heavy rains, uncovered coal ash pits can overflow and spill into nearby waterways. Ash pit embankments can also deteriorate and collapse, leading to massive ash releases that smother landscapes and contaminate waterways with toxic chemicals such as arsenic, mercury and selenium. According to Earthjustice, nearly half of coal ash impoundments as of 2022 had a “high” or “significant” impoundment hazard rating, which measures the potential loss of life and damage that would result from an impoundment failure.

Coal-fired power plants are often located alongside waterways to provide access to water for cooling. Ash pits at these plants put waterways at risk in case of overflow, leakage or flooding.Photo by Aaron Yoder, istock.com | iStock.com

Coal ash spills are common

Contaminants from coal ash stored in pits or landfills frequently leak into soil and groundwater, and can spill into adjacent rivers and streams. An analysis of electric utility reporting by Earthjustice in December 2018 found evidence of harmful groundwater contamination at 67 coal plants in 22 states. The contaminants found included arsenic, chromium, lead and selenium. Exposure to toxic substances in coal ash can lead to nausea and irritation of the nose and throat in the short-term, and liver and kidney damage, cardiac arrhythmia, and cancer in the long-term.

While leaks pose various risks to health and the environment, major spills can destroy ecosystems, landscapes and communities.

In December 2008, a coal ash pit at the Kingston Fossil Plant in Harriman, Tennessee, collapsed, causing 5.4 million cubic yards of ash to spill into the Emory and Clinch rivers, contaminating them with mercury, arsenic, lead and thallium. The spill also destroyed homes and covered 300 acres of land. The materials released were extremely hazardous; more than 50 people who worked to clean up the site have died of illness.

In February 2014, 39,000 tons of coal ash and 27 million gallons of coal ash pit water spilled into the Dan River in Eden, North Carolina, after a pipe burst at Duke Energy’s Dan River Steam Station, located at the river’s edge. In the wake of the spill, dead turtles were found onshore.

Coal ash covers the bank of North Carolina’s Dan River, downstream from a 2014 spill of coal ash pit water from a Duke Energy power plant.Photo by U.S. Environmental Protection Agency | Public Domain

Threat spotlight: Coal ash pits along the Ohio River

Across the country, 172 coal ash pits and landfills lie in FEMA 100-year flood zones or floodways – places where they are particularly vulnerable to flooding caused by extreme storms or other events.

Many of these sites sit along the Ohio River. As of 2021, there were 160 coal ash disposal sites in the Ohio River Valley. The Ohio River supplies drinking water for more than 5 million people, and sustains hundreds of animal species.

Discharges of coal ash have directly affected the Ohio River. In 2014, coal ash wastewater at a Kentucky power plant owned by Louisville Gas & Electric was found to be pouring into the Ohio River. However, despite a court settlement approved in 2016 that required the company to virtually end releases of coal ash wastewater to the river, testing three years later found contaminated groundwater from the plant flowing toward the Ohio River.

Protect America’s waterways from coal ash spills

Coal ash puts America’s streams and rivers at risk, but it doesn’t have to be that way. There are many ways that we can generate electricity without creating the toxic byproducts that result from coal combustion, and strong enforcement can reduce the chances that toxic coal ash will find its way into rivers and streams.

The EPA has recently taken action to reduce threats from coal ash, with the adoption of the Disposal of Coal Combustion Residuals Rule in 2015 and new rules in 2024 that govern inactive coal ash disposal facilities at former power plants. Some states have also acted. In the wake of the Dan River spill, North Carolina required Duke Energy to excavate coal ash from unlined pits at its power plants across the state.

Still, coal ash pits and ponds remain unnecessary threats to our waterways and our health. Policymakers should:

• Clean up existing coal ash ponds.
• Transition from coal to clean, renewable forms of energy that do not pollute our waterways.

Policymakers should also reject any efforts to weaken existing coal ash rules.

To find out more

To find out where active and legacy coal ash pits and landfills exist in your area, visit Earthjustice’s interactive website “Where are Coal Ash Dump Sites?”

To find detailed data on how specific coal-fired power plants in your area are complying with EPA regulations, visit the EPA’s website.

For information on how coal ash disposal is affecting groundwater, consult Earthjustice’s interactive map, which includes a list of coal ash disposal sites that are known to have contaminated groundwater.

Frontier Group intern Hailey Seo contributed to this article.