Toxic Coal Ash in Arizona: 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. There are a dozen coal ash dumpsites in Arizona.

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 remain 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. After years of litigation and grassroots activism, the EPA will extend clean up requirements to hundreds of old coal ash dumps across the country when it issues new regulations in the spring of 2024.

The Navajo Generating Station, near Page, Ariz., sits in haze behind Lake Powell.
The Navajo Generating Station, near Page, Ariz., in 2010. (Sylvia Schug / Getty Images)

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.
Coal ash dump sites across the United States. Use this map to understand where coal ash might be stored near you and how a given site may be impacted by EPA's expansion of the federal Coal Ash Rule. (Caroline Weinberg / Earthjustice)

10 Regulated Coal Ash Disposal Sites in Arizona

Arizona utilities operate 10 federally regulated landfills containing more than 90 million cubic yards of toxic waste at five power plants.

Coal ash has caused groundwater contamination at all of Arizona’s regulated dumpsites. One of these dumps is contaminating water at more than 20 times the levels permitted for certain pollutants.

Despite the serious and widespread water contamination, no Arizona company to date has initiated a plant-wide cleanup to restore groundwater, despite the legal requirement to do so.

Apache Cochise Arizona Electric Power Cooperative 1 lined pond Unsafe levels of lithium*
Cholla Joseph City Arizona Public Service Electric Co. 3 unlined ponds, 1 landfill Arsenic (x2), Boron (x25), Cobalt (x13), Fluoride (x1), Lithium (x18), Molybdenum (x9), Radium 226+228 (x2), Selenium (x3), Sulfate (x23)
Coronado St Johns SRP 2 unlined ponds, 1 landfill Lithium (x14), Radium 226+228 (x1)
Navajo Page SRP 1 landfill Unsafe levels of cobalt*
Springerville Springerville Tucson Electric Power 1 landfill Lithium (x26), Sulfate (x3), Thallium (x1)

* Based on industry monitoring data. See

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 Arizona, see Mapping the Coal Ash Contamination.

Two Coal Ash Legacy Ponds and Inactive Landfills in Arizona

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, Arizona hosts at least two 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.

Coronado St Johns SRP 0 2 Yes – Industry data

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.

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.

Earthjustice’s Clean Energy Program uses the power of the law and the strength of partnership to accelerate the transition to 100% clean energy.