(CNN) On Sunday, CNN published "Gambling 'America's Amazon,'" an investigation on a toxic coal ash pond in southern Alabama that experts say threatens one of the nation's most pristine wetlands.
Alabama Power, the state's largest utility, owns the waste site, which lacks a liner to contain the ash and is contaminating groundwater.
Federal regulations have required Alabama Power to close the pond, which it plans to do by sealing the coal ash in place. Environmental groups have called on the utility to dig it up and move it to a safer site.
The problem is not unique to Alabama. Coal ash is one of the largest types of industrial waste in the United States, and hundreds of coal ash ponds dot the country, according to data that federal regulations require pond operators to publish and was compiled by Earthjustice, a nonprofit that handles environmental lawsuits. Following changes in federal regulations, many utilities are wrestling with what to do with massive amounts of the material that have accumulated over decades.
Coal ash is an umbrella term for the residue that's left over when utilities burn coal. It contains metals — such as lead, mercury, chromium, selenium, cadmium and arsenic — that never biodegrade. Studies have shown these contaminants are dangerous to humans and have linked some to cancer, lung disease and birth defects.
There are several types of coal ash, including fly ash, which is fine and powdery, bottom ash which is heavy and coarse, and boiler slag, which is melted bottom ash. There's also flue gas desulfurization gypsum, also known as FGD gypsum, which is left over when utilities use scrubbers to reduce emissions during the coal burning process.
The coal ash recycling industry is significant. According to the American Coal Ash Association, utilities produced 78.6 million tons of coal ash in 2019. More than half was turned into other materials such as cement, grout and wallboard.
Before the 1970s, many utilities pumped their coal waste into the atmosphere, said attorney Lisa Evans, who has focused on coal ash litigation for more than 20 years and works for Earthjustice.
After Congress passed the Clean Air Act of 1970, which regulated power plants' air emissions, some facilities began storing much of their coal ash in dirt ditches, commonly known today as ash ponds or surface impoundments.
Some of them are large. The one CNN examined in Alabama spans 597 acres and is nearly the size of the National Mall.
There are an estimated 511 coal ash ponds in the United States, according to a CNN analysis of the data compiled by Earthjustice.
Coal plants produce electricity by burning coal to heat water, which becomes steam and passes through a turbine to produce electricity. Because of this, many coal plants have been constructed near river systems.
Environmentalists often raise two major concerns about coal ash ponds: that they can contaminate groundwater and that infrastructure could fail and trigger a catastrophic spill.
Earthjustice's data shows that, like the Alabama pond in CNN's investigation, nearly half — about 46% — of known ponds are unlined and have been or will be closed in place.
Environmental advocates say capping-in-place, the plan chosen by Alabama Power, is not always an effective option for coal ash ponds where coal ash sits below the water table, the point below which the ground is saturated with water, because the cap does not prevent contaminants from leaching into the surrounding area.
Across the United States, 40 or fewer ponds have a protective liner to contain the ash, and more than 200 have been shown to contaminate groundwater with toxic substances at levels that exceed federal safety standards, the Earthjustice data shows.
Humans can be exposed to leachate from coal ash ponds mainly through drinking water, particularly through private drinking wells that may not be monitored the way public systems are, or by consuming fish that have been affected. (In written responses to CNN, an Alabama Power spokesperson said the pond featured in CNN's investigation has no impact on any source of drinking water.)
There have been coal ash disasters in the past. In 2008, a spill near Kingston, Tennessee, blanketed up to 400 acres with coal ash, killing hundreds of fish, damaging more than a dozen homes and polluting nearby waterways. The clean-up took years and cost more than $1 billion.
After the Kingston disaster, the Environmental Protection Agency (EPA) reviewed the condition of dams at more than 500 coal ash ponds across the United States. And in 2015, the agency implemented its first-ever regulation on coal ash disposal.
The regulation — known as the "coal combustion residuals," or CCR, rule — forced utilities to close or remediate ponds that were unlined and contaminating groundwater above permitted levels. Depending on a pond's size, the EPA gave utilities between five and potentially 15 years to close them. In 2018, a federal court decision prompted the EPA to amend its rule. Today, some utilities may have until 2036 to complete closure of certain ash ponds.
The map at the top of this page can tell you if there's a coal waste site near you.
Federal regulations require utilities to publish information about their coal ash ponds on their websites. If you go to your local utility's website, you should be able to find information about a pond, including its location, size and whether it's contaminating groundwater.
Earthjustice, a nonprofit that handles environmental lawsuits, has also compiled the data from pond operators. The organization has information on more than 500 coal ash ponds across the United States, including an interactive map and spreadsheet. Users can use these to search by a variety of factors, including state, utility and name of the plant.
If you can't find the information you're seeking on a utility's website, you can check with state regulators. The EPA has compiled a list of those agencies.
The CCR rule requires utilities to publish results of their groundwater monitoring each year on their websites.
The EPA has a list of websites that provide compliance data on coal ash ponds.
Earthjustice and the Environmental Integrity Project, a nonprofit watchdog that advocates for better environmental law enforcement, also published a report in 2019 that examined industry groundwater monitoring data that may provide more information.
In the years following the Kingston disaster, the EPA conducted a series of assessments to suss out coal ash units with structural problems. The reports identified 50 units at 32 different facilities that were "high hazard potential units," based on federal guidelines for dams.
Utilities typically have to apply for permits to close ponds. The specific process varies by state, but guidelines the EPA published in 2017 say states' permitting programs should be "at least as protective as" federal regulations and should ensure public participation. Check your state regulator's website for announcements on upcoming hearings.