May 3, 2023
Toxic Coal Ash in Colorado: Addressing Coal Plants’ Hazardous Legacy
For decades, utilities disposed of coal ash — the hazardous substance left after burning coal for energy — by dumping it in unlined ponds and landfills. Colorado has 38 coal ash dumpsites.
After years of litigation and grassroots activism, on Apr. 25, 2024, the EPA issued a new rule that will force power plants to finally clean up their toxic coal ash. The EPA extended federal monitoring and cleanup requirements to hundreds of previously excluded older coal ash landfills and ponds that have been leaking toxic pollution into groundwater.
Note: Coal ash dumpsites referenced as “unregulated” throughout this page now are likely subject to federal regulation under the final rulemaking.
Coal ash contains hazardous pollutants including arsenic, boron, cobalt, chromium, lead, lithium, mercury, molybdenum, radium, selenium, and other heavy metals, which have been linked to cancer, heart and thyroid disease, reproductive failure, and neurological harm. In 2023, the EPA acknowledged that coal ash is even more dangerous than previously thought, with levels of arsenic and radiation that pose cancer risks.
Industry’s own data indicate that across the country 91% of coal plants are currently polluting groundwater above federal health standards with toxic pollutants.
Despite EPA’s 2015 Coal Ash Rule, which created the first-ever safeguards for coal ash disposal, many coal ash dumps remained unregulated due to sweeping exemptions for legacy coal ash ponds and inactive landfills. The exempted coal ash dumps are sited disproportionately in low-income communities and communities of color. The EPA extended clean up requirements to hundreds of old coal ash dumps across the country when it issued new regulations in the spring of 2024.
Coal ash remains one of our nation’s largest toxic industrial waste streams. U.S. coal plants continue to produce approximately 75 million tons every year.
In 2023, the EPA acknowledged widespread noncompliance with existing coal ash regulations and ramped up enforcement after designating coal ash a national enforcement priority.
Action Needed
The magnitude of harm from recklessly dumped toxic coal ash requires decisive action from federal and state regulators.
- Utilities must be required to comply with the law and immediately clean up their pollution.
- EPA and states must act quickly to ensure that utilities leave communities with sites that benefit rather than harm their health, environment, and economic status.
- EPA must take action to prohibit the use of coal ash as construction fill and make polluters clean up areas where ash was used as fill.
19 Regulated Coal Ash Disposal Sites in Colorado
Colorado utilities operate 19 federally regulated coal ash ponds and landfills containing more than 26 million cubic yards of toxic waste at eight power plants.
At every Colorado coal ash dumpsite that has been evaluated, coal ash has caused significant groundwater contamination.
Some of these dumps are contaminating water at more than 20-30 times the permitted levels of certain pollutants, and one of them — Comanche Generating Station — has been required to pay EPA penalties for improper disposal of coal ash waste.
Three Colorado plants are in the top 50 most-contaminated ash sites in the nation.
Despite the serious and widespread water contamination, no Colorado company to date has initiated a plant-wide cleanup to restore groundwater, despite the legal requirement to do so.
| Cherokee | Denver | Xcel Energy | 4 unlined ponds | Boron (x2), Lithium (x3), Molybdenum (x1), Sulfate (x3) |
| Clear Spring Ranch | Fountain | Colorado Springs Utilities | 1 landfill | Boron (x2), Selenium (x4) |
| Comanche | Pueblo | Xcel Energy | 1 unlined pond, 1 landfill | Not evaluated |
| Hayden | Hayden | Xcel Energy | 1 landfill | Boron (x27), Cobalt (x1), Molybdenum (x34), Sulfate (x27) |
| Nucla | Nucla | Tri-State Generation and Transmission Assoc. | 1 landfill | Arsenic (x3), Fluoride (x1), Lithium (x83), Molybdenum (x1), Sulfate (x4) |
| Pawnee | Brush | Xcel Energy | 2 lined ponds, 1 landfill | Lithium (x4), Sulfate (x10) |
| Rawhide | Wellington | Platte River Power Authority | 2 unlined ponds, 1 landfill | Boron (x1), Cobalt (x2), Lithium (x14), Molybdenum (x1), Selenium (x2), Sulfate (x8), Thallium (x1) |
| Valmont | Boulder | Xcel Energy | 3 unlined ponds, 1 landfill | Arsenic (x2), Boron (x9), Cobalt (x4), Lead (x1), Lithium (x6), Mercury (x13), Molybdenum (x6), Selenium (x58), Sulfate (x11), Thallium (x2) |
All data on groundwater contamination from coal ash derived from the utilities’ publicly accessible CCR Compliance Data and Information websites, and exceedances were calculated by Environmental Integrity Project.
For more information on regulated coal ash sites in Alabama and throughout the U.S., see Mapping the Coal Ash Contamination.
19 Coal Ash Legacy Ponds and Inactive Landfills in Colorado
March 2024 Update: The table below underestimates the legacy units that may be regulated by EPA’s upcoming CCR Legacy Pond Rule. Additional legacy units at specific plants may be found in the national map, above.
In addition, Colorado hosts at least 19 inactive coal ash landfills and legacy ponds that escaped federal regulation. The exact number remains unknown because utilities were not required to report these sites.
These dumps are almost certainly contaminating water and threatening health and the environment; however, monitoring data are not currently available for most unregulated sites.
As we anticipate EPA’s proposed rule on legacy ponds and unregulated landfills in May 2023, a concern remains that the agency will not address coal ash that was dumped off site or used as fill.
| Arapahoe | Denver | Public Service Co. of Colorado | 6 | 0 | Unknown |
| Cameo | Palisade | Xcel Energy | 2 | 0 | Unknown |
| Craig | Craig | Alaska Power and Telephone Co. | 2 | 1 | Unknown |
| Hayden | Hayden | Xcel Energy | 0 | 1 | Yes – Industry data |
| Martin Drake | Colorado Springs | City of Colorado Springs | 4 | 1 | Unknown |
| Rawhide | Wellington | Platte River Power Authority | 0 | 1 | Yes – Industry data |
| Valmont | Boulder | Xcel Energy | 0 | 1 | Yes – Industry data |
These data were developed by using EPA datasets relied upon in their 2007 and 2014 CCR risk assessments (Human and Ecological Risk Assessment of Coal Combustion Residuals) and comparing those datasets to the universe of regulated units.
All industry data on evidence of site contamination from coal ash derived from the utilities’ publicly accessible CCR Compliance Data and Information websites, and exceedances were calculated by Environmental Integrity Project.
For More Information
Christine Santillana, Senior Legislative Counsel, Earthjustice, csantillana@earthjustice.org
Lisa Evans, Senior Counsel, Earthjustice, levans@earthjustice.org.
More on Coal Ash in Colorado
- Poisonous Coverup: The Widespread Failure of the Power Industry to Clean Up Coal Ash Dumps (November 3, 2022)
- Will Fracking-Induced Earthquakes Cause the Next Coal Ash Disaster? (April 20, 2016)
- Tr-Ash Talk: It’s About Time (April 4, 2012)
- Tr-Ash Talk: EPA Delays Leave Americans at Risk (May 18, 2011)
Coal Ash in States, Territories, Regions
Puerto Rico (En Español)
Earthjustice fights in the courts for a long-term solution to the toxic menace of coal ash. And we act on behalf of dozens of clients and over 100 coalition partners to defeat legislative attempts to subvert federally enforceable safeguards of coal ash.
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